DETAILED ACTION
Notice of Pre-AIA or AIA Status
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
Continued Examination Under 37 CFR 1.114
A request for continued examination under 37 CFR 1.114, including the fee set forth in 37 CFR 1.17(e), was filed in this application after final rejection. Since this application is eligible for continued examination under 37 CFR 1.114, and the fee set forth in 37 CFR 1.17(e) has been timely paid, the finality of the previous Office action has been withdrawn pursuant to 37 CFR 1.114. Applicant's submission filed on 01/29/2026 has been entered.
Response to Remarks
Applicant’s arguments filed on 01/29/2026 have been fully considered but were not found persuasive over the previous prior art rejection of record for the reasons set forth below. See updated claims 1, 3-14, 17-18, and 20-21 rejections over Su in view of Ohashi below; claims 15-16 rejections over Su in view of Ohashi and further in view of Hatanaka below; and claim 19 rejection over Su in view of Ohashi and further in view of Kwon below.
Applicant argues “These features in combination with other features recited in claim 1 is not disclosed or rendered obvious by Su, Ohashi, Hatanaka, Bizet, and Kwon, either taken alone or in combination.” (see e.g. page 8 of applicant’s argument).
Examiner respectfully disagrees. Su discloses the claimed positive electrode structure including sequential lamination of a current collector, a first mixture layer, and a second mixture layer, wherein the first mixture layer includes a first binder containing PVDF, which is a fluorine-based homopolymer, and wherein the second mixture layer includes a second binder that may include a vinylidene fluoride-hexafluoropropylene copolymer, which is a fluorine-based copolymer (see e.g. paragraphs [0006], [0013], [0051], and [0084] of Su). Ohashi further discloses a fluoroplastic binder, including PVDF or a vinylidene fluoride copolymer such as a vinylidene fluoride-hexafluoropropylene copolymer, to which an acrylic polymer is bonded, wherein the acrylic polymer includes acrylic acid ester and/or methacrylic acid ester monomer units, including methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, and butyl methacrylate (see e.g. Column 1, lines 61-67; Column 2, lines 1-10 and 51-65; and Column 3, lines 61-67 of Ohashi). These monomer units overlap with the claimed miscible functional group derived from C1 to C10 alkyl(meth)acrylate. Ohashi also teaches that such a fluoroplastic/acrylic polymer binder improves adhesion between the electrode activator and the collector and improves cycle characteristics of the cell. Therefore, it would have been obvious to modify Su’s fluorine-based copolymer binder in the second mixture layer using the fluoroplastic/acrylic polymer binder teachings of Ohashi in order to improve adhesion and cycle performance. For the above reason, applicant’s argument is not persuasive.
Applicant argues “the ratio of molecular weights of polymers is not disclosed to be a result-effective variable, the molecular weight of the claimed second binder is not recognized to directly impact adhesion, viscosity, film-forming ability, and cycle life stability, as argued previously, and the Office does not provide any evidence to support its allegation.” (see e.g. page 9 of applicant’s argument).
Examiner respectfully disagrees. The claimed ratio is not an isolated or unrelated parameter, but rather is a mathematical expression of the relative molecular weights of the first and second polymeric binders used in adjacent electrode mixture layers. The applied art recognizes that binder properties affect adhesion and cell performance. Su teaches that the binder allows better adhesion between the active material layer and the cathode current collector and also recognizes that binder content affects the compaction density of the cathode active material layer (see e.g. paragraph [0051] of Su). Ohashi teaches that PVDF and fluorinated resins have poor adhesion to metals and that the disclosed fluoroplastic/acrylic polymer binder improves adhesion between the electrode activator and the collector and improves cycle characteristics (see e.g. Column 1, lines 43-64 and Column 3, lines 61-67 of Ohashi). Ohashi further teaches that the acrylic polymer content must be controlled because too little acrylic polymer results in poor adhesion, whereas too much acrylic polymer results in poor binder resistance and swelling in organic electrolyte solvents (see e.g. Column 2, lines 7-17 of Ohashi). Thus, the applied art recognizes that binder structure and binder properties affect adhesion, electrolyte resistance, swelling, and cell cycle performance. It would have been obvious to a person of ordinary skill in the art to select compatible molecular weights for Su’s first and second fluorine-based binders, as modified by Ohashi, to balance adhesion, coating processability, swelling resistance, mechanical integrity, and interfacial stability between the first and second mixture layers. For the above reason, applicant’s argument is not persuasive.
Applicant argues “Su and Ohashi do not expressly disclose numerical molecular weight values for the first and second binders, as admitted by the Office. The other applied references, Hatanaka, Bizet, and Kwon, suffer from the same shortcomings and thus fail to cure the deficiencies of Su and Ohashi. Therefore, the applied art, either taken alone or in combination, would not have disclosed the ratio of the molecular weight for the first and second binders meeting the claimed range, much less that the ratio affects a characteristic of an electrode or battery.” (see e.g. page 10 of applicant’s argument).
Examiner respectfully disagrees. The rejection does not require Su or Ohashi to expressly disclose the exact numerical molecular weight ratio recited in Formula 1. Rather, the rejection is based on the obvious selection and optimization of known polymer binder molecular weights in view of the recognized importance of binder adhesion, coating integrity, swelling resistance, and cycle performance. Su and Ohashi disclose the same general type of binders used in the same type of lithium secondary battery electrode environment, namely fluorine-based polymer binders used in cathode mixture layers. Ohashi expressly recognizes that binder modification and binder composition affect adhesion, swelling, resistance to electrolyte solvents, and cell performance. Accordingly, a person of ordinary skill in the art would have had reason to select compatible molecular weights for the first and second binders in Su’s adjacent electrode layers, as modified by Ohashi, in order to obtain predictable improvements in adhesion, processability, and interfacial stability. Applicant’s own specification further confirms that Formula 1 is directed to preventing deterioration of interface performance between the first and second mixture layers and preventing lifespan reduction due to deviation in binder molecular weight. Therefore, the claimed ratio represents an optimization of known binder properties for known electrode-performance purposes. For the above reason, applicant’s argument is not persuasive.
Applicant argues “Essentially, no disclosure of a relationship between the claimed ratio and any result in the applied art was established, and there is no mention that adjusting the relative viscosities/molecular weights is a routine polymer-processing consideration. Because the claimed ratio of binder molecular weight is not recognized in the applied art to be a result-effective variable, one of ordinary skill in the art would not have had a reason to perform routine experimentation to arrive at the claimed ratio.” (see e.g. page 10 of applicant’s argument).
Examiner respectfully disagrees. The applied art need not use Applicant’s exact mathematical ratio in order to render the claim obvious. The claimed ratio is derived from the molecular weights of two polymer binders used in adjacent electrode layers. Su and Ohashi recognize that binder properties are important to adhesion and battery performance, and Ohashi specifically teaches controlling fluoroplastic/acrylic polymer binder composition to balance adhesion against electrolyte resistance and swelling. A person of ordinary skill in the art would have understood that the molecular weights of polymeric binders affect binder viscosity, coating behavior, film formation, adhesion, and mechanical integrity. Therefore, once Su teaches adjacent cathode mixture layers containing fluorine-based binders and Ohashi teaches acrylic-modified fluoroplastic binders for improved adhesion and cycle characteristics, it would have been obvious to select compatible molecular weights for the respective binders so that the adjacent layers have suitable coating processability, adhesion, swelling resistance, and interfacial stability. The claimed ratio merely reflects routine optimization of the relative molecular weights of known binder materials used for known electrode-performance purposes. For the above reason, applicant’s argument is not persuasive.
Applicant argues “absent of any disclosure of a relationship between the claimed ratio and any result in the applied art, one of ordinary skill in the art would not have had a reason to design an electrode based on the ratio of polymer molecular weights.” (see e.g. page 10 of applicant’s argument).
Examiner respectfully disagrees. A person of ordinary skill in the art would not have needed to begin with Applicant’s exact ratio as a target in order for the claimed subject matter to be obvious. The relevant inquiry is whether the claimed ratio would have resulted from routine selection and optimization of known binder properties in view of the applied art. Su teaches a two-layer positive electrode using fluorine-based binders, and Ohashi teaches fluoroplastic/acrylic polymer binders that improve adhesion and cycle characteristics. Ohashi also teaches that binder composition must be controlled because binder properties affect adhesion, swelling, and resistance to electrolyte solvents. In view of these teachings, a person of ordinary skill in the art would have had reason to choose compatible molecular weights for the first and second binders to provide suitable coating behavior, adhesion, and interfacial stability in Su’s laminated electrode structure. For the above reason, applicant’s argument is not persuasive.
Applicant argues “the Office fails to articulate any plausible rationale as to why it would have been routine optimization to arrive at the claimed ratio, which is not a result-effective variable for the various reasons discussed above, and why a person of ordinary skill in the art would have had a reasonable expectation of success to formulate the claimed range.” (see e.g. page 11 of applicant’s argument).
Examiner respectfully disagrees. The rationale is that Su teaches a two-layer positive electrode structure using fluorine-based binders in the first and second mixture layers, while Ohashi teaches fluoroplastic/acrylic polymer binders for lithium-ion battery electrodes that improve adhesion and cycle characteristics. Since Su and Ohashi both concern electrode mixture layers for lithium secondary batteries and both recognize adhesion and cell performance as important binder-related properties, a person of ordinary skill in the art would have had reason to select and adjust the molecular weights of the first and second binders so that the binders are compatible in adjacent coated layers and provide suitable adhesion, coating processability, swelling resistance, and interfacial stability. A person of ordinary skill in the art would have had a reasonable expectation of success because the modification involves using known fluorine-based polymer binders and known acrylic-modified fluoroplastic binders for their known purpose in the same lithium battery electrode environment. For the above reason, applicant’s argument is not persuasive.
Applicant argues “the applied art does not disclose or render obvious the claimed range for the content of the miscible functional group.” (see e.g. page 11 of applicant’s argument).
Examiner respectfully disagrees. Ohashi discloses a fluoroplastic binder to which at least one acrylic polymer is bonded, wherein the acrylic polymer includes monomer units selected from esters of acrylic acid and/or methacrylic acid (see e.g. Column 1, lines 66-67 and Column 2, lines 1-6 of Ohashi). Ohashi further discloses that the fluoroplastic may be PVDF or a vinylidene fluoride copolymer, including a copolymer of vinylidene fluoride and hexafluoropropylene (see e.g. Column 2, lines 51-56 of Ohashi). Ohashi also discloses specific alkyl acrylate and alkyl methacrylate monomer units, including methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, and butyl methacrylate (see e.g. Column 2, lines 61-65 of Ohashi), which overlap with the claimed C1 to C10 alkyl(meth)acrylate miscible functional groups. Ohashi discloses that the acrylic polymer content is 0.1 to 20 wt%, preferably 0.2 to 20 wt%, and more preferably 0.3 to 5 wt% of the grafted fluoroplastic (see e.g. Column 2, lines 7-10 of Ohashi). Although Ohashi expresses the acrylic polymer content in weight percent rather than mol percent, the disclosed weight percent range reasonably corresponds to molar contents overlapping the claimed 3 mol% to 10 mol% range when calculated based on the repeat-unit molecular weights of vinylidene fluoride and the disclosed alkyl acrylate or alkyl methacrylate monomer units. Therefore, Ohashi discloses or renders obvious a fluorine-based copolymer having a miscible functional group content overlapping the claimed range. In the case where the prior art discloses a range that overlaps with the claimed range, a prima facie case of obviousness exists. See MPEP 2144.05(I). For the above reason, applicant’s argument is not persuasive.
Applicant argues “In rejecting the claims, the Office cites Bizet as teaching an acrylic copolymer with miscible functional groups that are 10 mol% of the copolymer. Considering that Bizet’s binder contains 0.1%-25% acrylic copolymer by weight… a content of methacrylic acid groups in the binder is at most 1.75 mol%, which is outside of the claimed range.” (see e.g. pages 11-12 of applicant’s argument):
Examiner respectfully disagrees. Applicant’s argument is not persuasive because the rejection of amended claims 1 and 18 does not rely on Bizet to teach the claimed miscible functional group content. Rather, as set forth in the updated rejections below, Ohashi discloses a fluoroplastic/acrylic polymer binder wherein the acrylic polymer content is 0.1 to 20 wt%, preferably 0.2 to 20 wt%, and more preferably 0.3 to 5 wt% of the grafted fluoroplastic. Ohashi’s disclosed acrylic polymer content range reasonably corresponds to molar contents overlapping the claimed 3 mol% to 10 mol% range of claim 1 and the claimed 3 mol% to 8 mol% range of claim 18 when expressed on a molar basis using the repeat-unit molecular weights of vinylidene fluoride and Ohashi’s disclosed alkyl acrylate or alkyl methacrylate monomer units. Therefore, Applicant’s arguments directed to Bizet do not overcome the Su and Ohashi rejection of amended claims 1 and 18. For the above reason, applicant’s argument is not persuasive.
Applicant argues “One of ordinary skill in the art would not have had a reason to modify Bizet’s content of methacrylic acid groups in the binder by increasing the proportion of the acrylic polymer because Bizet discloses problems of deterioration of the electrode as a result of the swelling of the acrylic polymer… Therefore, one of ordinary skill in the art would have been discouraged from modifying the content of methacrylic acid group to beyond 1.75 mol% as disclosed in Bizet.” (see e.g. page 12 of applicant’s argument).
Examiner respectfully disagrees. Applicant’s argument is not persuasive because amended claims 1 and 18 are rejected over Su in view of Ohashi, and the rejection does not require modifying Bizet’s binder composition. Ohashi expressly teaches using acrylic polymer bonded to fluoroplastic in order to improve adhesion and cycle characteristics. Ohashi also teaches that the acrylic polymer content should be controlled because too little acrylic polymer results in poor adhesion and too much acrylic polymer results in poor resistance and swelling in organic electrolyte solvents. This teaching would have motivated a person of ordinary skill in the art to select an acrylic polymer content within Ohashi’s disclosed range that balances improved adhesion with electrolyte resistance and reduced swelling. Thus, Ohashi teaches optimization within a disclosed range, not discouragement from the claimed range. For the above reason, applicant’s argument is not persuasive.
Applicant argues “The positive electrode of the present application exhibits a superior improved penetration resistance effect that leads to suppression of ignition when the electrode is penetrated by external force. This is achieved by simultaneously controlling a) the weight average molecular weight ratio of the binders, and b) the content of the miscible functional group included in the fluorine-based copolymer within the claimed specific ranges.” (see e.g. page 12 of applicant’s argument).
Examiner respectfully disagrees. Applicant’s evidence of alleged superior results has been considered but is not commensurate in scope with the breadth of claim 1. The pending claim broadly recites miscible functional groups derived from one or more monomers selected from (meth)acrylic acid, C1 to C10 alkyl(meth)acrylate, C1 to C10 alkyl(meth)acrylonitrile, and C1 to C10 alkyl(meth)acrylamide, and broadly recites a miscible functional group content of 3 mol% to 10 mol% of the fluorine-based copolymer. However, the relied-upon experimental data appears limited to specific binder systems and specific tested compositions, including examples centered around approximately 6 ± 1 mol% functional group content. The data does not establish that the alleged superior penetration resistance occurs across the full scope of the claimed 3 mol% to 10 mol% range or across all claimed monomer classes. Evidence of unexpected results must be reasonably commensurate in scope with the claims. Accordingly, the limited examples are insufficient to overcome the prima facie case of obviousness established by Su in view of Ohashi. For the above reason, applicant’s argument is not persuasive.
Applicant argues “Su does not specify that the first and second layers must respectively contain a fluorinated homopolymer and a fluorinated copolymer having a miscible functional group as claimed.” (see e.g. page 13 of applicant’s argument).
Examiner respectfully disagrees. Su expressly discloses that the first cathode active material layer and the second cathode active material layer may each include a binder selected from a group including polyvinylidene fluoride and a vinylidene fluoride-hexafluoropropylene copolymer (see e.g. paragraph [0013] of Su). Su also specifically discloses PVDF in the first cathode active material layer of Embodiment 1 (see e.g. paragraph [0084] of Su). Ohashi supplies the teaching of a fluoroplastic binder, including PVDF or vinylidene fluoride copolymers such as PVDF-HFP, having bonded acrylic or methacrylic ester monomer units. Therefore, Su in view of Ohashi renders obvious a first mixture layer including a first binder containing a fluorine-based homopolymer and a second mixture layer including a second binder containing a fluorine-based copolymer having the claimed miscible functional group. For the above reason, applicant’s argument is not persuasive.
Applicant argues “Considering this, one ordinary skilled in the art would understand that when combining the binder of Ohashi, i.e., the fluorine-based plastic having acrylic acid and methacrylic acid ester units, with the teachings of Su, the binder of Ohashi will be combined with the binder of the alleged first active material layer in contact with the current collector to improve the adhesive strength of the composite layer. Therefore, the modification derived from the combined teachings of Su and Ohashi differs from the present application in terms of the location of the fluorine-based copolymer containing the miscible functional group.” (see e.g. page 13 of applicant’s argument).
Examiner respectfully disagrees. Applicant’s argument improperly limits the reason for using Ohashi’s binder to only the first layer. Su teaches that both the first cathode active material layer and the second cathode active material layer include binders, and Su’s list of suitable binders for the cathode active material layers includes both PVDF and vinylidene fluoride-hexafluoropropylene copolymer (see e.g. paragraph [0013] of Su). Although Ohashi discusses improved adhesion between the electrode activator and collector, Ohashi’s fluoroplastic/acrylic polymer binder is not limited to use only in a layer directly contacting a metal current collector. Ohashi broadly teaches electrode mixture layers containing the binder and teaches improved adhesion and cycle characteristics in lithium-ion cells. In Su’s laminated electrode structure, the second mixture layer must also maintain cohesion, adhesion to the underlying first mixture layer, coating integrity, and cycle stability. Therefore, it would have been obvious to use Ohashi’s acrylic-modified fluoroplastic binder in Su’s second mixture layer to improve adhesion, binder integrity, and cycle performance. For the above reason, applicant’s argument is not persuasive.
Applicant argues “Su and Ohashi do not disclose anything about the weight-average molecular weight of the binder, Ohashi has a composition with a lower content of miscible functional groups than the present application, and Su and Ohashi only mention that the adhesion between the active material layer and the current collector and the resulting life performance of the cell can be improved, but do not disclose anything about the penetration resistance or safety against external force.” (see e.g. pages 13-14 of applicant’s argument).
Examiner respectfully disagrees. First, express disclosure of the precise claimed molecular weight ratio is not required where the claimed ratio would have resulted from routine selection and optimization of known polymer binder properties to achieve known binder-related results, including adhesion, coating integrity, electrolyte resistance, swelling resistance, and cycle performance. Second, Ohashi’s acrylic polymer content is not limited to a content below the claimed range. Ohashi discloses acrylic polymer contents of 0.1 to 20 wt%, preferably 0.2 to 20 wt%, and more preferably 0.3 to 5 wt% of the grafted fluoroplastic, which reasonably correspond to molar contents overlapping the claimed range when expressed on a molar basis. Third, the prior art does not need to recognize the exact same advantage relied upon by Applicant. The applied art provides sufficient reason to modify Su with Ohashi in order to improve adhesion and cycle characteristics. The fact that Applicant alleges an additional benefit of penetration resistance does not render the claimed structure nonobvious where the structure would have been obvious for the reasons set forth in the rejection. For the above reason, applicant’s argument is not persuasive.
Applicant argues “Su and Ohashi do not appear to disclose electrodes with improved penetration resistance, and the applied art does not suggest that the claimed composition can improve the penetration resistance of the positive electrode.” (see e.g. page 14 of applicant’s argument).
Examiner respectfully disagrees. The motivation to combine Su and Ohashi is not limited to improving penetration resistance. Su already concerns lithium-ion battery safety and discloses a two-layer cathode structure in the context of improving safety performance in a penetration test. Ohashi supplies the binder modification for improving adhesion and cycle characteristics. A reference need not teach the same advantage or recognize the same problem identified by Applicant if the claimed structure would have been obvious for another reason. Here, Su provides the claimed layered electrode structure, and Ohashi provides a known fluoroplastic/acrylic polymer binder modification for improving adhesion and cycle performance in lithium-ion battery electrodes. Therefore, the combination provides an adequate reason to arrive at the claimed electrode even if Ohashi does not expressly discuss penetration resistance. For the above reason, applicant’s argument is not persuasive.
Applicant argues “the correlation between interlayer adhesion and nail penetration results is not easily inferable, as shown by comparing Example 1 and Comparative Example 4. Thus, the claimed positive electrode surprisingly exhibited superior characteristics.” (see e.g. page 14 of applicant’s argument).
Examiner respectfully disagrees. Applicant’s evidence has been considered but is insufficient to outweigh the prima facie case of obviousness. The data is limited to selected examples and comparative examples and does not demonstrate unexpected results commensurate with the full scope of the pending claims. Claim 1 broadly encompasses multiple different miscible functional group monomer classes and the entire range of 3 mol% to 10 mol%, while the relied-upon examples appear limited to particular binders and particular tested functional group contents. Further, the evidence does not establish that the alleged results are due to the full breadth of the claimed features rather than other unclaimed or narrowly disclosed aspects of the tested examples, such as specific binder identities, specific active materials, specific layer compositions, or specific processing conditions. Therefore, Applicant’s evidence does not overcome the obviousness rejection. For the above reason, applicant’s argument is not persuasive.
Applicant argues “Dependent claims 3-21 each depends from and incorporate all the features of independent claim 1, including the above-noted claim features. Thus, at least based on their dependency on allowable independent claim 1 and on their own merits, Applicant respectfully submits that claims 3-21 are also allowable over the applied art and requests withdrawal of the rejection of claims 3-21.” (see e.g. page 14 of applicant’s argument).
Examiner respectfully disagrees. Claim 1 is not allowable for the reasons discussed above and as set forth in the updated rejection below. Therefore, Applicant’s argument that dependent claims 3-21 are allowable based on their dependency from claim 1 is not persuasive. Furthermore, the dependent claims do not include additional limitations that overcome the applied prior art for the reasons set forth in the specific claim rejections below. Claims 1, 3-14, 17-18, and 20-21 remain rejected over Su in view of Ohashi; claims 15-16 remain rejected over Su in view of Ohashi and further in view of Hatanaka; and claim 19 remains rejected over Su in view of Ohashi and further in view of Kwon. For the above reason, applicant’s argument is not persuasive.
In conclusion, the arguments and amendments filed were not found to be persuasive over the previous prior art rejection of record. The rejections of the claims have been updated to reflect the amendments where appropriate. See claims 1, 3-14, 17-18, and 20-21 rejections over Su in view of Ohashi below; claims 15-16 rejections over Su in view of Ohashi and further in view of Hatanaka below; and claim 19 rejection over Su in view of Ohashi and further in view of Kwon below.
Summary
This is a continued examination non-final office action for application 17/915,645 in response to the amendments filed on 01/29/2026. Claims 1 and 3-21 are under examination.
The text of those sections of Title 35, U.S. Code not included in this action can be found in a prior Office action.
Priority
Acknowledgment is made of applicant’s claim for foreign priority under 35 U.S.C. 119 (a)-(d). The certified copies have been filed in parent Application Nos. KR10-2021-0039316 filed on 03/26/2021 and PCT/KR2021/016787 filed on 11/16/2021.
Information Disclosure Statement
The information disclosure statements (IDS)s submitted on 09/29/2022, 11/03/2023, 07/23/2024 and 09/09/2024 are being considered by the examiner.
Claim Rejections - 35 USC § 103
Claims 1, 4-14, 17-18 and 20-21 are rejected under 35 U.S.C. 103 as being unpatentable over Su et al. (US-20200144605-A1) and further in view of Ohashi et al. (US-6228533-B1).
Regarding Claim 1, Su discloses a positive electrode for a lithium secondary battery (see e.g. “cathode” in paragraph [0005] and FIG. 1), the positive electrode comprising a structure including a laminate (see e.g. FIG. 1) including sequential lamination of a current collector (see e.g. “cathode current collector” in paragraph [0006] and part number 11 in FIG. 1), a first mixture layer (see e.g. “a first cathode active material layer” in paragraph [0006] and part number 12 in FIG. 1), and a second mixture layer (see e.g. “a second cathode active material layer” in paragraph [0006] and part number 13 in FIG. 1), in order (see e.g. FIG. 1),
wherein the first mixture layer includes a first binder containing a fluorine-based homopolymer (see e.g. “the first cathode active material layer… include a binder and a conductive agent, wherein the binder is selected from the group consisting of polyvinylidene fluoride” in paragraph [0013] and “The lithium iron phosphate slurry, composed of 95.8 wt % of lithium iron phosphate (LiFePO4), 2.8 wt % of polyvinylidene fluoride (PVDF) and 1.4 wt % of conductive carbon black” in Embodiment 1 paragraph [0084]),
wherein the second mixture layer includes a second binder containing a fluorine-based copolymer (see e.g. “the second cathode active material layer… include a binder… wherein the binder is… a vinylidene fluoride-hexafluoropropylene copolymer” in paragraph [0013]).
Su does not explicitly disclose that the second mixture layer includes a second binder containing a fluorine-based copolymer having a miscible functional group derived from one or more monomers selected from the group consisting of (meth)acrylic acid, C1 to C10 alkyl(meth)acrylate, C1 to C10 alkyl(meth)acrylonitrile, and C1 to C10 alkyl(meth)acrylamide, wherein a content of the miscible functional group is in a range of 3 mol% to 10 mol% of the fluorine-based copolymer.
Ohashi, however, in the same field of endeavor, electrode binders for lithium secondary batteries, discloses an electrode mixture layer including a fluoroplastic binder to which at least one acrylic polymer is bonded, wherein the monomer units of the acrylic polymer consist mainly of at least one monomer unit selected from esters of acrylic acid and/or methacrylic acid (see e.g. Column 1, lines 66–67 and Column 2, lines 1–6 of Ohashi). Ohashi further discloses that the fluoroplastic may be polyvinylidene fluoride (PVDF) or a copolymer thereof, such as a copolymer of vinylidene fluoride and hexafluoropropylene (see e.g. “For the present invention, PVDF means homopolymers of vinylidenefluoride (VF2) and copolymers of VF2 and at least another fluorinated comonomer preferably chosen among tetrafluoroethylene, hexafluoropropylene, trifluoroethylene and/or chlorotrifluoroethylene that can be used alone or in combination” in Column 2, lines 51–56 of Ohashi). Ohashi also discloses specific alkyl acrylate and alkyl methacrylate monomer units, including methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, and butyl methacrylate (see e.g. Column 2, lines 61–65 of Ohashi), which overlap with the claimed C1 to C10 alkyl(meth)acrylate monomers.
Ohashi further discloses that the content of the acrylic polymer is 0.1 to 20% by weight, preferably 0.2 to 20% by weight, and more preferably 0.3 to 5% by weight of the grafted fluoroplastic (see e.g. Column 2, lines 7–10 of Ohashi).
Although Ohashi expresses the acrylic polymer content in weight percent rather than mol percent, Ohashi’s disclosed acrylic polymer content reasonably corresponds to a molar content overlapping the presently claimed range of 3 mol% to 10 mol% when calculated based on the repeat-unit molecular weights of vinylidene fluoride and the disclosed alkyl acrylate or alkyl methacrylate monomer units. For example, vinylidene fluoride has a repeat-unit molecular weight of about 64 g/mol, methyl acrylate has a repeat-unit molecular weight of about 86 g/mol, and methyl methacrylate has a repeat-unit molecular weight of about 100 g/mol. Thus, Ohashi’s disclosure of acrylic polymer in an amount up to 5 wt% of the grafted fluoroplastic reasonably corresponds to a molar content of acrylic monomer units of about 3 mol% or greater, depending on the selected acrylic monomer species, thereby overlapping the claimed range of 3 mol% to 10 mol% of the fluorine-based copolymer.
Thus Ohashi discloses a range that overlaps with the range claimed by the instant application. In the case where the prior art discloses a range that overlaps with the claimed range, a prima facie case of obviousness exists. See MPEP 2144.05 (I).
Ohashi also teaches that this fluoroplastic/acrylic polymer binder improves adhesion between the electrode activator and the collector and improves cycle characteristics of the cell (see e.g. “The present invention provides electrodes for batteries and cells whose adhesion between the electrode activator and the collector is improved so as the cycle property of the cells” in Column 1, lines 61–64 and “The present invention provides electrodes whose adhesion between the electrode activator and the collector is improved. When these electrodes are used in batteries, the capacity of discharge is not deteriorated after repeated charge-discharge cycles. The present invention is useful particularly in lithium-ion cells” in Column 3, lines 61–67 of Ohashi). Therefore, it would have been obvious to a person of ordinary skill in the art, before the effective filing date of the claimed invention, to modify the fluorine-based copolymer binder of the second mixture layer of Su et al. with the acrylic polymer functionality taught by Ohashi et al. in order to improve adhesion and cycle characteristics a suggested by Ohashi.
With respect to the limitation requiring that the first binder and the second binder satisfy Formula 1, wherein 1.0 ≤ Mw2nd/Mw1st ≤ 2.0, neither Su nor Ohashi explicitly discloses specific numerical weight average molecular weight values for the first and second binders. However, Su and Ohashi both recognize binder adhesion and electrode integrity as important properties of lithium secondary battery electrodes (see e.g. “the binder allows a better adhesion between the active material layer to the cathode current collector” in paragraph [0051] of Su and “The present invention provides electrodes for batteries and cells whose adhesion between the electrode activator and the collector is improved so as the cycle property of the cells” in Column 1, lines 61–64 of Ohashi). Ohashi further teaches that the amount and nature of the acrylic polymer must be controlled because too little acrylic polymer results in poor adhesion and too much acrylic polymer results in poor binder resistance and swelling in organic electrolyte solvents (see e.g. Column 2, lines 7–17 of Ohashi). Thus, the applied art recognizes that binder composition and binder properties affect adhesion, electrolyte resistance, swelling, and cell cycle performance.
Applicant’s own specification confirms that Formula 1 is directed to these same binder-property concerns, namely preventing deterioration of the interface performance between the first mixture layer and the second mixture layer and preventing lifespan reduction due to deviation of the weight average molecular weight of the first binder and the second binder (see e.g. Page 13, lines 9–19 of the Instant Specification). Accordingly, the claimed ratio is not an unrelated or arbitrary parameter, but rather is the mathematical relationship between the molecular weights of two known fluorine-based binders used in adjacent electrode mixture layers, where binder molecular weight would have been understood by a person of ordinary skill in the art to affect coating viscosity, film formation, adhesion, swelling resistance, mechanical integrity, and interfacial stability.
Therefore, it would have been obvious to a person of ordinary skill in the art, before the effective filing date of the claimed invention, to select and adjust the molecular weights of Su’s first fluorine-based homopolymer binder and second fluorine-based copolymer binder, as modified by Ohashi, such that the molecular weight ratio falls within the claimed range of 1.0 to 2.0 in order to balance adhesion, coating processability, swelling resistance, and interfacial integrity between the first and second mixture layers. Selection of suitable polymer molecular weights for known electrode binders would have involved routine optimization of known binder properties to obtain a predictable result, namely improved adhesion and stable cycle performance.
Regarding Claim 4, Su in view of Ohashi discloses the positive electrode of claim 1 (see e.g. claim 1 rejection above).
Su does not explicitly disclose that the content of the miscible functional group is in a range of 5 mol% to 10 mol% of the fluorine-based copolymer.
Ohashi, however, discloses a fluoroplastic binder to which at least one acrylic polymer is bonded, wherein the monomer units of the acrylic polymer consist mainly of at least one monomer unit selected from esters of acrylic acid and/or methacrylic acid (see e.g. Column 1, lines 66–67 and Column 2, lines 1–6 of Ohashi). Ohashi further discloses that the fluoroplastic may be polyvinylidene fluoride or a copolymer of vinylidene fluoride and another fluorinated comonomer, including hexafluoropropylene (see e.g. Column 2, lines 51–56 of Ohashi). Thus, Ohashi discloses a fluorine-based copolymer having acrylic or methacrylic ester functional groups bonded thereto.
Ohashi further discloses that the main monomer units of the acrylic polymer may be alkyl esters of acrylic acid or methacrylic acid, including methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, and butyl methacrylate (see e.g. Column 2, lines 61–65 of Ohashi). These monomer units overlap with the claimed C1 to C10 alkyl(meth)acrylate miscible functional group.
Ohashi also discloses that the content of the acrylic polymer is 0.1 to 20% by weight, preferably 0.2 to 20% by weight, and more preferably 0.3 to 5% by weight of the grafted fluoroplastic (see e.g. Column 2, lines 7–10 of Ohashi). Although Ohashi expresses the acrylic polymer content in weight percent rather than mol percent, Ohashi’s disclosed acrylic polymer content reasonably corresponds to molar contents overlapping the presently claimed range of 5 mol% to 10 mol% when calculated based on the repeat-unit molecular weights of vinylidene fluoride and Ohashi’s disclosed alkyl acrylate or alkyl methacrylate monomer units. For example, vinylidene fluoride has a repeat-unit molecular weight of about 64 g/mol, methyl acrylate has a repeat-unit molecular weight of about 86 g/mol, and methyl methacrylate has a repeat-unit molecular weight of about 100 g/mol. Based on these repeat-unit molecular weights, acrylic polymer contents within Ohashi’s disclosed 0.1 to 20 wt% range, such as about 7 to 15 wt% depending on the selected acrylic monomer species, reasonably correspond to about 5 mol% to 10 mol% acrylic or methacrylic ester monomer units in the fluorine-based copolymer.
Accordingly, Ohashi discloses a range that overlaps with the range claimed by the instant application. In the case where the prior art discloses a range that overlaps with the range claimed by the instant application, a prima facie case of obviousness exists. See MPEP 2144.05(I).
Ohashi also teaches that this fluoroplastic/acrylic polymer binder improves adhesion between the electrode activator and the collector and improves cycle characteristics of the cell (see e.g. “The present invention provides electrodes for batteries and cells whose adhesion between the electrode activator and the collector is improved so as the cycle property of the cells” in Column 1, lines 61–64 and “The present invention provides electrodes whose adhesion between the electrode activator and the collector is improved. When these electrodes are used in batteries, the capacity of discharge is not deteriorated after repeated charge-discharge cycles. The present invention is useful particularly in lithium-ion cells” in Column 3, lines 61–67 of Ohashi). Therefore, it would have been obvious to a person of ordinary skill in the art, before the effective filing date of the claimed invention, to modify the fluorine-based copolymer binder of the second mixture layer of Su et al. with the acrylic polymer functionality taught by Ohashi et al. in order to improve adhesion and cycle characteristics a suggested by Ohashi.
Regarding Claim 5, Su in view of Ohashi discloses the positive electrode of claim 1 (see e.g. claim 1 rejection above).
Su further discloses that the first mixture includes 95.8 wt% of a first active material, 2.8 wt% of a first binder, and 1.5 wt % of a first conductive material (see e.g. "The lithium iron phosphate slurry, composed of 95.8 wt % of lithium iron phosphate (LiFePO4), 2.8 wt % of polyvinylidene fluoride (PVDF) and 1.4 wt % of conductive carbon black" in paragraph [0084]).
Su discloses points that lie within the range claimed by the instant application. In the case where the prior art discloses a point within the claimed range, a prima facie case of obviousness exists. See MPEP 2144.05 (I).
Regarding Claim 6, Su in view of Ohashi discloses the positive electrode of claim 5 (see e.g. claim 5 rejection above).
Su further discloses that the first active material includes lithium iron phosphate and is represented by LiFePO4 (see e.g. "The lithium iron phosphate slurry, composed of 95.8 wt % of lithium iron phosphate (LiFePO4)" in paragraph [0084]). This corresponds directly with the claimed species, Li1-xFe1-yM1y(PO4-z)Xz, where M1 denotes at least one species selected from the group consisting of Al, Mg and Ti, and X denotes at least one species selected from the group consisting of F, S and N, and -0.5 ≤ x ≤ 0.5, 0 ≤ y ≤ 0.5 and 0 ≤ z ≤ 0.1. In the case where x = 0, y = 0, and z = 0 the claimed species becomes LiFePO4 which is the same species disclosed by Su.
Su discloses points that lie within the range claimed by the instant application. In the case where the prior art discloses a point within the claimed range, a prima facie case of obviousness exists. See MPEP 2144.05 (I).
Regarding Claim 7, Su in view of Ohashi discloses the positive electrode of claim 1 (see e.g. claim 1 rejection above).
Su further discloses that the content of the first binder is 2.8 wt% and the content of first conductive material is 1.4 wt% (see e.g. "2.8 wt % of polyvinylidene fluoride (PVDF) and 1.4 wt % of conductive carbon black" in Embodiment 1 paragraph [0084]) Thus a/c = 2.8/1.4 = 2, where a denotes a content of a first active material and c denotes a content of a first conductive material.
Su discloses a point that lies within the range claimed by the instant application. In the case where the prior art discloses a point within the claimed range, a prima facie case of obviousness exists. See MPEP 2144.05 (I).
Regarding Claim 8, Su in view of Ohashi discloses the positive electrode of claim 1 (see e.g. claim 1 rejection above).
Su further discloses that the second mixture has a second binder content between 0.5 and 4 wt% (see e.g. "the content of the binder of the second cathode active material layer is from about 0.5 wt % to about 4 wt % based on the total weight of the second cathode active material layer" in paragraph [0051]) and a second conductive active material content between 0.5 wt% and 5 wt% (see e.g. " the content of the conductive agent of the second cathode active material layer is from about 0.5 wt % to about 5 wt % based on the total weight of the second cathode active material layer." in paragraph [0052]). Based on this it would be obvious to a person of ordinary skill in the art that the remaining portion of the second mixture must be the second active material in a content between 91 wt % and 99 wt%.
Su discloses ranges which lie within or overlap with the ranges claimed by the instant application. In the case where the prior art discloses a range that lies within or overlaps with the claimed range, a prima facie case of obviousness exists. See MPEP 2144.05 (I).
Regarding Claim 9, Su in view of Ohashi discloses the positive electrode of claim 1 (see e.g. claim 1 rejection above).
Su further discloses that a content of first binder is 2.8 wt% (see e.g. "2.8 wt % of polyvinylidene fluoride (PVDF)" in paragraph [0084]) and a content of second binder is 0.8 wt% (see e.g. "0.8 wt % of polyvinylidene fluoride (PVDF)" in paragraph [0084]). Thus, Su discloses that b > b' where b denotes a content of the first binder and b' denotes a content of the second binder.
Su discloses a point that lies within the range claimed by the instant application. In the case where the prior art discloses a point within the claimed range, a prima facie case of obviousness exists. See MPEP 2144.05 (I).
Regarding Claim 10, Su in view of Ohashi discloses the positive electrode of claim 1 (see e.g. claim 1 rejection above).
Su further discloses that the thickness of the first mixture layer is 8 μm (see e.g. "the thickness of the first cathode active material layer was 8 μm" in paragraph [0084]).
Su discloses a point that lies within the range claimed by the instant application. In the case where the prior art discloses a point within the claimed range, a prima facie case of obviousness exists. See MPEP 2144.05 (I).
Regarding Claim 11, Su in view of Ohashi discloses the positive electrode of claim 1 (see e.g. claim 1 rejection above).
Su further discloses that the thickness of the first mixture layer is 8 μm (see e.g. " the thickness of the first cathode active material layer was 8 μm" in paragraph [0084]).
Su discloses a point that lies within the range claimed by the instant application. In the case where the prior art discloses a point within the claimed range, a prima facie case of obviousness exists. See MPEP 2144.05 (I).
Regarding Claim 12, Su in view of Ohashi discloses a lithium secondary battery (see e.g. "electrochemical device" in paragraph [0016] and FIGs. 4a and 4b of Su) comprising the positive electrode according to claim 1 (see e.g. claim 1 rejection above), a negative electrode (see e.g. "anode" in paragraph [0016] of Su), and a separator (see e.g. "separator" in paragraph [0016] of Su) positioned between the positive electrode and the negative electrode (see e.g. "the separator is disposed between the anode and the cathode, and the anode" in paragraph [0016] of Su).
Regarding Claim 13, Su in view of Ohashi discloses the positive electrode of claim 1 (see e.g. claim 1 rejection above).
Su does not disclose that the miscible functional group is derived from one or more monomers selected from the group consisting of (meth)acrylic acid and C1 to C10 alkyl(meth)acrylate.
Ohashi, however, discloses that the miscible functional group is derived from one or more monomers selected from the group consisting of (meth)acrylic acid (see e.g. "methacrylic acid" in Column 2 line 6 of Ohashi).
Ohashi also teaches that this type of mixture provides electrodes with improved adhesion between the mixture and the current collector, and that when this mixture is used in batteries, the discharge capacity does not deteriorate after repeated charge-discharge cycles, making this useful in lithium-ion batteries (see e.g. Column 3 lines 61-67 of Ohashi). Therefore, it would have been obvious to a person of ordinary skill in the art, before the effective filing date of the claimed invention, to modify the miscible functional group of Su et al. such that it is derived from one or more monomers selected from the group consisting of (meth)acrylic acid as taught by Ohashi et al. in order to improve the adhesion between the mixture and the current collector as suggested by Ohashi
Regarding Claim 14, Su in view of Ohashi disclose the positive electrode of claim 1 (see e.g. claim 1 rejection above).
Su does not disclose that the miscible functional group is derived from C1 alkyl(meth)acrylate.
Ohashi, however, discloses that the miscible functional group is derived from C1 alkyl(meth)acrylate (see e.g. "methylacrylate" in Column 2 line 64 of Ohashi; methylmethacrylate is a specific embodiment of a C1 alkyl(meth)acrylate, because “C1 alkyl” refers to a one-carbon substituent (methyl), and methacrylate is the same functional methacrylate moiety).
Ohashi also teaches that this type of mixture provides electrodes with improved adhesion between the mixture and the current collector, and that when this mixture is used in batteries, the discharge capacity does not deteriorate after repeated charge-discharge cycles, making this useful in lithium-ion batteries (see e.g. Column 3 lines 61-67 of Ohashi). Therefore, it would have been obvious to a person of ordinary skill in the art, before the effective filing date of the claimed invention, to modify the miscible functional group of Su et al. such that the miscible functional group is derived from C1 alkyl(meth)acrylate as taught by Ohashi et al. in order to improve the adhesion between the mixture and the current collector as suggested by Ohashi.
Regarding Claim 17, Su in view of Ohashi discloses the positive electrode of claim 1 (see e.g. claim 1 rejection above).
Su in view of Ohashi does not explicitly disclose that the first binder and the second binder satisfy Formula 1 wherein 1.05 ≤ Mw2nd / Mw1st ≤ 1.95.
However, as discussed in the response to arguments and claim 1 rejection above, the molecular weight of polymeric binders is a result effective variable that directly impacts adhesion, viscosity, film-forming ability, and cycle-life stability. See MPEP 2144.05(II). Applicant’s own specification admits that Formula 1 is directed to achieving these same properties (see e.g. page 13, lines 9–19 of the Instant Specification). It would have been obvious to a person of ordinary skill in the art to adjust the molecular weights of the first and second binders such that their ratio falls within the narrower range of 1.05–1.95 in order to predictably optimize adhesion and cycle performance.
Regarding Claim 18, Su in view of Ohashi discloses the positive electrode of claim 1 (see e.g. claim 1 rejection above).
Su does not explicitly disclose that the content of the miscible functional group is in a range of 3 mol% to 8 mol% of the fluorine-based copolymer.
Ohashi, however, discloses a fluoroplastic binder to which at least one acrylic polymer is bonded, wherein the monomer units of the acrylic polymer consist mainly of at least one monomer unit selected from esters of acrylic acid and/or methacrylic acid (see e.g. Column 1, lines 66-67 and Column 2, lines 1-6 Ohashi). Ohashi further discloses that the fluoroplastic may be polyvinylidene fluoride or a copolymer of vinylidene fluoride and another fluorinated comonomer, including hexafluoropropylene (see e.g. Column 2, lines 51-56 of Ohashi). Thus, Ohashi discloses a fluorine-based copolymer having acrylic or methacrylic ester functional groups bonded thereto.
Ohashi further discloses that the main monomer units of the acrylic polymer may be alkyl esters of acrylic acid or methacrylic acid, including methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, and butyl methacrylate (see e.g. Column 2, lines 61-65 of Ohashi). These monomer units overlap with the claimed C1 to C10 alkyl(meth)acrylate miscible functional group.
Ohashi also discloses that the content of the acrylic polymer is 0.1 to 20% by weight, preferably 0.2 to 20% by weight, and more preferably 0.3 to 5% by weight of the grafted fluoroplastic (see e.g. Column 2, lines 7-10 of Ohashi). Although Ohashi expresses the acrylic polymer content in weight percent rather than mol percent, Ohashi’s disclosed acrylic polymer content reasonably corresponds to molar contents overlapping the presently claimed range of 3 mol% to 8 mol% when calculated based on the repeat-unit molecular weights of vinylidene fluoride and Ohashi’s disclosed alkyl acrylate or alkyl methacrylate monomer units. For example, vinylidene fluoride has a repeat-unit molecular weight of about 64 g/mol, methyl acrylate has a repeat-unit molecular weight of about 86 g/mol, and methyl methacrylate has a repeat-unit molecular weight of about 100 g/mol. Based on these repeat-unit molecular weights, acrylic polymer contents within Ohashi’s disclosed range reasonably correspond to molar contents falling within or overlapping the claimed 3 mol% to 8 mol% range.
Accordingly, Ohashi discloses a range that overlaps with the range claimed by the instant application. In the case where the prior art discloses a range that overlaps with the range claimed by the instant application, a prima facie case of obviousness exists. See MPEP 2144.05(I).
Ohashi also teaches that this fluoroplastic/acrylic polymer binder improves adhesion between the electrode activator and the collector and improves cycle characteristics of the cell (see e.g. “The present invention provides electrodes for batteries and cells whose adhesion between the electrode activator and the collector is improved so as the cycle property of the cells” in Column 1, lines 61–64 and “The present invention provides electrodes whose adhesion between the electrode activator and the collector is improved. When these electrodes are used in batteries, the capacity of discharge is not deteriorated after repeated charge-discharge cycles. The present invention is useful particularly in lithium-ion cells” in Column 3, lines 61–67 of Ohashi). Therefore, it would have been obvious to a person of ordinary skill in the art, before the effective filing date of the claimed invention, to modify the fluorine-based copolymer binder of the second mixture layer of Su et al. with the acrylic polymer functionality taught by Ohashi et al. in order to improve adhesion and cycle characteristics a suggested by Ohashi.
Regarding Claim 20, Su in view of Ohashi discloses the positive electrode of claim 7 (see e.g. claim 7 rejection above).
Su further discloses that the first mixture layer satisfies Formula 3 (see e.g. "2.8 wt % of polyvinylidene fluoride (PVDF) and 1.4 wt % of conductive carbon black" in paragraph [0084]) The content of the first binder is 2.8 wt% and the content of first conductive material is 1.4 wt%, thus a/c = 2.8/1.4 = 2 where a denotes a content of a first active material and c denotes a content of a first conductive material.
Su discloses a point that lies within the range claimed by the instant application. In the case where the prior art discloses a point within the claimed range, a prima facie case of obviousness exists. See MPEP 2144.05 (I).
Su does not disclose that the first mixture layer satisfies Formula 2 which states 4 ≤ a/b ≤ 20, where a denotes a content of a first active material, b denotes a content of the first binder, and c denotes a content of a first conductive material.
Ohashi, however, discloses a first mixture layer which satisfies Formula 2 (see e.g. "In order to prepare a cathode, 92 parts by weight of LiCoO2 as cathode activator and 6 parts of graphite as electro-conductive additive were dispersed in a solution of N-methylpyrolidone in which 8 parts by weight of the same binder that was used for the preparation of the anode was dissolved to obtain a slurry (paste)." in Column 4 lines 43-48 of Ohashi). Ohashi discloses that a = 92 and b = 8, thus a/b = 11.5.
Ohashi discloses a point that lies within the range claimed by the instant application. In the case where the prior art discloses a point within the claimed range, a prima facie case of obviousness exists. See MPEP 2144.05 (I).
Ohashi also teaches that this type of mixture provides electrodes with improved adhesion between the mixture and the current collector, and that when this mixture is used in batteries, the discharge capacity does not deteriorate after repeated charge-discharge cycles, making this useful in lithium-ion batteries (see e.g. Column 3 lines 61-67 of Ohashi). Therefore, it would have been obvious to a person of ordinary skill in the art, before the effective filing date of the claimed invention, to modify the first mixture layer of Su et al. such that the first mixture layer satisfies Formula 2 which states 4 ≤ a/b ≤ 20, where a denotes a content of a first active material, b denotes a content of the first binder, and c denotes a content of a first conductive material as taught by Ohashi et al. in order to improve the adhesion between the mixture and the current collector as suggested by Ohashi.
Regarding Claim 21, Su in view of Ohashi discloses the positive electrode of claim 9 (see e.g. claim 9 rejection above).
Su further discloses that the first mixture layer and the second mixture layer satisfy Formulas 4-5.
Specifically,
Formula 4 (a < a′): Su discloses that the first active material comprises 95.8 wt% LiFePO4 (see e.g. paragraph [0084]) and the second active material comprises 97.8 wt% LiCoO2 (see e.g., paragraph [0084]). Thus, Su teaches that the content of the first active material (a) is less than the content of the second active material (a′), satisfying Formula 4.
Formula 5 (b > b′): Su discloses that the content of the first binder is 2.8 wt% PVDF and the content of the second binder is 0.8 wt% PVDF (see e.g. paragraph [0084]). Thus, Su teaches that the first binder content (b) is greater than the second binder content (b′), satisfying Formula 5.
Su does not explicitly disclose Formula 6 (c < c′). Su discloses that the content of the first conductive material is 1.4 wt% carbon black and the content of the second conductive material is 1.4 wt% carbon black (see e.g. paragraph [0084]).
While Su teaches equal amounts (c = c′), Ohashi discloses that the amount of conductive additive is increased relative to the active material loading (see e.g., “6 parts of graphite as electro-conductive additive” relative to 92 parts LiCoO₂ and 8 parts binder in Column 4, lines 53–59 of Ohashi). It would have been obvious to a person of ordinary skill in the art that the relative content of conductive additive in the second mixture layer could be adjusted upward to improve conductivity of high-loading LiCoO₂ cathodes, which are known to have poorer conductivity than LiFePO₄. Therefore, it would have been obvious to adjust the amount of the second conductive material relative to the first conductive material to satisfy c < c′ in order to balance conductivity across the stacked cathode layers. Furthermore, Ohashi discloses that the conductive additive is 5.66% by weight (6/106 = 5.66) and thus, if substituted with the second conductive additive of Su, would disclose Formula 6.
Ohashi also teaches that this type of mixture provides electrodes with improved adhesion between the mixture and the current collector, and that when this mixture is used in batteries, the discharge capacity does not deteriorate after repeated charge-discharge cycles, making this useful in lithium-ion batteries (see e.g. Column 3 lines 61-67 of Ohashi). Therefore, it would have been obvious to a person of ordinary skill in the art, before the effective filing date of the claimed invention, to modify the first mixture layer and second mixture layer of Su et al. such that the first mixture layer and second mixture layer satisfy Formula 6 which states c < c’ as taught by Ohashi et al. in order to improve the adhesion between the mixture and the current collector as suggested by Ohashi.
Claims 15-16 are rejected under 35 U.S.C. 103 as being unpatentable over Su et al. (US-20200144605-A1) in view of Ohashi et al. (US-6228533-B1) as applied to claim 1 above, and further in view of Hatanaka et al. (US-20200083516-A1).
Regarding Claim 15, Su in view of Ohashi disclose the positive electrode of claim 1 (see e.g. claim 1 rejection above).
Su in view of Ohashi does not disclose that the miscible functional group is derived from C1 to C10 alkyl(meth)acrylonitrile.
Hatanaka, however, in the same field of endeavor, polymer binders for electrochemical applications, discloses the miscible functional group that is (meth)acrylonitrile (see e.g. "illustrative examples of hydrophilic functional group-containing (meth)acrylic monomers include... (meth)acrylonitrile" in paragraph [0067] of Hatanaka; (meth)acrylonitrile is the C1 alkyl(meth)acrylonitrile variant).
Hatanaka further teaches that the use of this functional group in the binder allows for better adhesion and enables energy storage devices to be made even smaller and thinner which is desirable in the art (see e.g. paragraphs [0003] and [0013] of Hatanaka). Therefore, it would have been obvious to a person of ordinary skill in the art, before the effective filing date of the claimed invention, to modify the miscible functional group of Su et al. in view of Ohashi et al. such that the miscible functional group is (meth)acrylonitrile as taught by Hatanaka et al. in order to allow for better adhesion and enable energy storage devices to be made even smaller and thinner as suggested by Hatanaka.
Regarding Claim 16, Su in view of Ohashi disclose the positive electrode of claim 1 (see e.g. claim 1 rejection above).
Su in view of Ohashi does to disclose that the miscible functional group is derived from C1 to C10 alkyl(meth)acrylamide.
Hatanaka, however, discloses the miscible functional group that is (meth)acrylamide (see e.g. "illustrative examples of hydrophilic functional group-containing (meth)acrylic monomers include... (meth)acrylamide" in paragraph [0067] of Hatanaka; (meth)acrylamide is the C1 alkyl(meth)acrylamide variant).
Hatanaka further teaches that the use of this functional group in the binder allows for better adhesion and enables energy storage devices to be made even smaller and thinner which is desirable in the art (see e.g. paragraphs [0003] and [0013] of Hatanaka). Therefore, it would have been obvious to a person of ordinary skill in the art, before the effective filing date of the claimed invention, to modify the miscible functional group of Su et al. in view of Ohashi et al. such that the miscible functional group is (meth)acrylamide as taught by Hatanaka et al. in order to allow for better adhesion and enable energy storage devices to be made even smaller and thinner as suggested by Hatanaka.
Claims 3 and 19 is rejected under 35 U.S.C. 103 as being unpatentable over Su et al. (US-20200144605-A1) in view of Ohashi et al. (US-6228533-B1) as applied to claim 1 above, and further in view of Kwon et al. (US-20140246085-A1).
Regarding Claim 3, Su in view of Ohashi disclose the positive electrode of claim 1 (see e.g. claim 1 rejection above).
Su in view of Ohashi are silent as to the properties of the binders use and thus do not disclose that the weight average molecular weight (Mw1st) of the first binder is in a range of 10,000 to 1,000,000 g/mol.
Kwon, however, in the same field of endeavor coatings for electrochemical application discloses fluorine-based polymers having a weight average molecular weight of 50,000 to 1,000,000 (see e.g. "The fluorine-based polymer may have a weight average molecular weight of 50,000 to 1,000,000" in paragraph [0035] of Kwon). Both the binders disclosed in Su and Ohashi are fluorine-based polymers (see e.g. claim 1 rejection above).
Kwon discloses a range that falls within the range claimed by the instant application. In the case where the prior art discloses a range within the claimed range, a prima facie case of obviousness exists. See MPEP 2144.05 (I).
Kwon further teaches that the polymer may have an excellent adhesive property to the base film (see e.g. paragraph [0029] of Kwon). Therefore, it would have been obvious to a person of ordinary skill in the art, before the effective filing date of the claimed invention, to modify the first binder of Su et al. in view of Ohashi et al. such that the weight average molecular weight (Mw1st) of the first binder is in a range of 10,000 to 1,000,000 g/mol.as taught by Kwon et al. in order to have a polymer with excellent adhesive properties as suggested by Kwon.
Regarding Claim 19, Su in view of Ohashi disclose the positive electrode of claim 1 (see e.g. claim 1 rejection above).
Su in view of Ohashi are silent as to the properties of the binders use and thus do not disclose that the weight average molecular weight (Mw1st) of the first binder is in a range of 200,000 to 500,000 g/mol.
Kwon, however, in the same field of endeavor coatings for electrochemical application discloses fluorine-based polymers having a weight average molecular weight of 50,000 to 1,000,000 (see e.g. "The fluorine-based polymer may have a weight average molecular weight of 50,000 to 1,000,000" in paragraph [0035] of Kwon). Both the binders disclosed in Su and Ohashi are fluorine-based polymers (see e.g. claim 1 rejection above).
Kwon discloses a range that encompasses the range claimed by the instant application. In the case where the prior art discloses a range that encompasses the claimed range, a prima facie case of obviousness exists. See MPEP 2144.05 (I).
Kwon further teaches that the polymer may have an excellent adhesive property to the base film (see e.g. paragraph [0029] of Kwon). Therefore, it would have been obvious to a person of ordinary skill in the art, before the effective filing date of the claimed invention, to modify the first binder of Su et al. in view of Ohashi et al. such that the weight average molecular weight (Mw1st) of the first binder is in a range of 200,000 to 500,000 g/mol as taught by Kwon et al. in order to have a polymer with excellent adhesive properties as suggested by Kwon.
Conclusion
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/J.J.E./Examiner, Art Unit 1723
/NICHOLAS P D'ANIELLO/Primary Examiner, Art Unit 1723
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