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and the fee set forth in 37 CFR 1.17(e) has been timely paid, the finality of the previous Office action has been withdrawn pursuant to 37 CFR 1.114.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 August 20, 2026 has been entered.
Summary
The Applicant’s arguments and claim amendments received on August 20, 2026 have been entered into the file. Currently, claim 1 is amended; claims 2 and 7 are cancelled; and claims 9-12 are new; resulting in claims 1, 3-6, and 8-12 pending for examination.
Claim Rejections - 35 USC § 103
In the event the determination of the status of the application as subject to AIA 35 U.S.C. 102 and 103 (or as subject to pre-AIA 35 U.S.C. 102 and 103) is incorrect, any correction of the statutory basis (i.e., changing from AIA to pre-AIA ) for the rejection will not be considered a new ground of rejection if the prior art relied upon, and the rationale supporting the rejection, would be the same under either status.
The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action:
A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made.
The factual inquiries for establishing a background for determining obviousness under 35 U.S.C. 103 are summarized as follows:
1. Determining the scope and contents of the prior art.
2. Ascertaining the differences between the prior art and the claims at issue.
3. Resolving the level of ordinary skill in the pertinent art.
4. Considering objective evidence present in the application indicating obviousness or nonobviousness.
Claims 1, 3-6, and 8-12 are rejected under 35 U.S.C. 103 as being unpatentable over Hiroki, et al. (JP 2020095853 A) in view of Tamaki, et al. (US PGPub 2013/0004845 A1, cited on IDS), and further in view of Katsushi, et al. (WO 2016208480 A1), as evidenced by Ballisteri, A., et al. Thermal Decomposition of Acrylonitrile Copolymers Investigated by Direct Pyrolysis in the Mass Spectrometer Die Makromolekulare Chemie: Macromolecular Chemistry and Physics, Vol 180, no. 12 (1979), pp. 2835-2842.
Regarding claims 1 and 6, Hiroki teaches a non-aqueous electrolyte secondary battery with a negative electrode (20) including a negative electrode current collector (21; substrate), a first negative electrode active material layer (22A), and a second negative electrode active material layer (22B), layered in that order (¶ [0007], Ln. 49-53; Fig. 3). The first negative electrode active material layer (22A) contains a first graphite particle group (1) (¶ [0018], Ln. 163-164) and the second negative electrode active material layer (22A) contains a second graphite particle group (2) and a ceramic particle group (3) (¶ [0020], Ln. 190-191). Hiroki further teaches that in forming the negative electrode, the first negative electrode paste and second negative electrode paste are applied to the current collector and dried and pressed (¶ [0059], Ln. 526-531). The porosity of the second active material layer is greater than the porosity of the first active material layer (¶ [0007], Ln. 61). The ceramic particle group (3) forms pores (voids) in the second electrode active material layer (22B) (¶ [0021], Ln. 202-203). As shown in the cross-section view in Figure 3, the second active material layer (22B) has more voids than the first active material layer. Hiroki further teaches that the ceramic particles enter the gaps between the graphite particles, forming voids and allowing the second active material layer to have a relatively high porosity (¶ [0008], Ln. 69-72). The pores serve as diffusion paths for lithium ions and the high porosity promotes diffusion of lithium ions, improving input characteristics (¶ [0009], Ln. 76-78).
Hiroki is silent to the number density of voids having a diameter of 3 µm or more per mm2 unit area in a transverse cross section parallel to the thickness direction. Therefore, the reference does not expressly teach that the first negative electrode active material layer has a number density of voids having a diameter of 3 µm or more per unit area of less than 200/mm2 and the second negative electrode active material layer has a number density of voids having a diameter of 3 µm or more per unit area of from 200/mm2 to 1500/mm2.
It would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, to adjust the number density of voids having a diameter of 3 µm or more per unit area to less than 200/mm2 in the first negative electrode active material layer and to adjust the number density of voids having a diameter of 3 µm or more per unit area to 200-1500/mm2 in the second negative electrode active material layer through routine optimization. As taught by Hiroki, having a relatively high porosity in the second active material layer promotes the diffusion of lithium ions, improving input characteristics. Additionally, it is well-known in the art that a low porosity of active material results in higher energy density. Based on the teachings of Hiroki, it would be obvious to adjust the amount of ceramic particles used in the second active material layer in order to adjust the number of voids. It would be obvious to one ordinary skill in the art to optimize the porosity of the negative electrode active material layer in order to promote the diffusion of lithium ions while maintaining a high energy density of the battery.
As stated above, Hiroki teaches that the first negative electrode active material layer (22A) contains a first graphite particle group (1; first active material particles) (¶ [0018], Ln. 163-164) and the second negative electrode active material layer (22A) contains a second graphite particle group (2; second active material particles) (¶ [0020], Ln. 190-191). Additionally, Hiroki teaches that graphite particles with a relatively small particle size in the surface layer of a negative electrode active material increases reaction area between electrolyte and the graphite particles, improving input characteristics (¶ [0004], Ln. 27-32). Hiroki teaches that the first graphite particle group has a first average particle diameter “d1” and the second graphite particle group has a second average particle diameter “d2” (¶ [0023], Ln. 228-231), further teaching that d1 and d2 satisfy the relationship 0.8≤d2/d1≤1.13 (¶ [0025], Ln. 244-245). Hiroki teaches that the first average particle size is more than 10 µm and less than 30 µm (¶ [0027], Ln. 257), overlapping the claimed range of more than 10 µm and less than 20 µm. In the case where the claimed ranges "overlap or lie inside ranges disclosed by the prior art" a prima facie case of obviousness exists (MPEP 2144.05 (I)). Using the relationship between d1 and d2, the resulting second average particle size is more than 8 µm and less than 34 µm. Further, Hiroki teaches that improved input characteristics may be achieved when the second average particle size is slightly smaller (¶ [0090], Ln. 746-748). Hiroki does not expressly teach the second average particle size is 4 µm to 7 µm.
It would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, to modify the second average particle size of Hiroki to try a second average particle diameter very close to the lower range of 8 µm, such as 7 µm, with a reasonable expectation of success. One of ordinary skill in the art would be motivated to include a second graphite particle group having a slightly smaller average particle size in order to improve the input characteristics. As the lower range taught by Hiroki for the second average particle size is 8 µm, one of ordinary skill in the art would find it obvious to try 7 µm, which is very close. A prima facie case of obviousness exists where the claimed ranges or amounts do not overlap with the prior art but are merely close (MPEP 2144.05(I)).
Hiroki is silent to teach the mass density per unit volume of the negative electrode and therefore, does not expressly teach that the mass density per unit volume of the negative electrode active material layer is 1.2 g/cm3 or more.
Tamaki teaches a lithium-ion battery comprising a cathode and an anode, wherein the anode has at least two layers: a collector-side active material layer (24a; first active material layer) provided on the anode collector; and a surface-side active material layer (24b; second active material layer) provided on the collector-side active material layer (¶ [0013], Ln. 1-9). The collector-side active material layer (24a; first active material layer) and the surface-side active material layer (24b; second active material layer) are constructed of an anode active material (21) consisting of carbon material (¶ [0053], Ln. 8-9). The specific surface area of the anode active material in the surface-side active material layer (24b; second active material layer) is greater than the specific surface area of the anode active material in the collector-side active material layer (24a; first active material layer) (¶ [0053], Ln. 11-15) and, as shown in Figure 5, the particle size of the anode active material in the surface-side active material layer (24b; second active material layer) is smaller than the particle size of the anode active material in the collector-side active material layer (24a; first active material layer). Tamaki further teaches that the density of the active material layer is approximately 1.0-1.5 g/cm3 (¶ [0062], Ln. 7-10). Specifically, examples 2-1 – 2-6 and 4-1 – 4-6 teach a density of 1.4 g/cm3 (Table 1, Examples 2-1 – 2-6, 4-1 – 4-6). The density is adjusted during the pressing process (¶ [0063], Ln. 20-23) and Tamaki teaches that a density of the active material layers in this range allows for retention of electrolyte (¶ [0062], Ln. 6-7).
It would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, to modify the negative electrode of Hiroki to have a mass density per unit volume between 1.0 and 1.5 g/cm3, such as 1.4 g/cm3, as taught by Tamaki, meeting the limitations of claims 1 and 6. The density adjustment could be made during the compression of the negative electrode. One would be motivated to adjust the density within this range in order to allow for adequate retention of the electrolyte within the electrode.
Hiroki further teaches that the second negative electrode active material layer (22A) contains a second graphite particle group (2) and a ceramic particle group (3) (¶ [0020], Ln. 190-191). The ceramic particle group (3) forms pores (voids) in the second electrode active material layer (22B) (¶ [0021], Ln. 202-203). The ceramic particles form pores because they make it difficult for gaps between the particles of the second negative electrode active material layer (22B) to be crushed during compression of the electrode (¶ [0021], Ln. 202-206). Hiroki does not expressly teach that the second electrode active material layer (22B) includes a thermoplastic resin that is degradable in an oxygen-containing atmosphere at a temperature of 200 °C or more.
Katsushi teaches a negative electrode for a nonaqueous secondary battery wherein the negative electrode includes a negative electrode active material, a negative electrode binder, and organic hollow particles having an outer shell made of a thermoplastic resin (¶ [0006], Ln. 60-62). Katsushi teaches that the organic hollow particles introduce voids to the negative electrode active material layer (¶ [0015], Ln. 142-144). Katsushi teaches a process of applying the negative electrode slurry to a current collector, drying, and pressing, and provides a vacuum drying temperature of 120 °C (¶ [0109], Ln. 1450-1454). Katsushi further teaches that including organic hollow particles in the slurry for the negative electrode results in a secondary battery with excellent cycle characteristics (¶ [0012], Ln 116-119). The particle size of the organic hollow particles is preferably 0.1-50 µm, more preferably 1.0-35 µm (¶ [0028], Ln. 348-349). The thermoplastic resin is formed by polymerization of a polymerizable monomer component and a crosslinking agent (¶ [0039], Ln. 507-510). The polymerizable monomer is preferably a nitrile-based monomer such as acrylonitrile or methacrylonitrile (¶ [0040], Ln. 516, 521-522) and further includes a monomer other than the nitrile monomer such as a (meth)acrylic acid ester monomer, a carboxyl group-containing monomer, a vinyl ester monomer, or an acrylamide monomer (¶ [0043], Ln. 562-565). Ballisteri teaches that the thermal decomposition of pendant ester groups in methyl acrylate and methyl methacrylate copolymers occurs at 200-260 °C. Additionally, Ballisteri teaches that polyacrylonitrile decomposition fragments are typically detected in the 240-300 °C temperature range (pg. 2835). Based on these teachings, one of ordinary skill in the art would understand that the thermal degradation temperature of the thermoplastic resin of Katsushi is at a temperature above 200 °C.
It would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, to modify the second negative electrode active material layer (22B) of Hiroki to include organic hollow particles to form voids in the active material layer as taught by Katsushi. Organic hollow particles serve the same purpose as the ceramic particles taught by Hiroki of forming voids in the active material layer. One would be motivated to use organic hollow particles as taught by Katsushi rather than ceramic particles in order to produce a secondary battery with excellent cycle characteristics. In applying the teachings of Katsushi, one of ordinary skill in the art would find it obvious to use organic hollow particles with a size of 1.0-35 µm, forming voids having diameters largely overlapping the claimed range of 3 µm or more. In the case where the claimed ranges "overlap or lie inside ranges disclosed by the prior art" a prima facie case of obviousness exists (MPEP 2144.05(I)). Additionally, in applying the void-forming process of Katsushi using organic hollow particles having a thermoplastic resin shell, one of ordinary skill in the art would find it obvious to apply the vacuum drying temperature of Katsushi. As Hiroki does not expressly teach the temperature at which the electrode is dried, one of ordinary skill in the art would find it obvious to look to the teachings of Katsushi. Thus, it would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, to dry the electrode layer of Hiroki in view of Tamaki and Katsushi at a similar temperature of 120 °C, based on the similarities in processing and common temperatures for vacuum drying. In the step of vacuum drying the negative electrode slurries, the thermoplastic resin shell of the organic hollow particle would shrink, forming voids.
Regarding claim 3, Hiroki in view of Tamaki and Katsushi teaches all of the limitations of claim 1 above. The relationship between particle size and specific surface area is well-known: the smaller the particle size, the larger the specific surface area. Therefore, as Hiroki teaches a second average particle size that is less than the first average particle size, Hiroki also teaches that the BET specific surface area of the second graphite particle group is more than the BET specific surface area of the first graphite particle group based on the provided average particle size.
Regarding claim 4, Hiroki in view of Tamaki and Katsushi teaches all of the limitations of claim 1 above. Additionally, Hiroki teaches that the mass density per unit volume of the second negative electrode active material layer (22B) is less than the mass density per unit volume of the first negative electrode active material layer (22A), as a higher porosity would result in a lower density. Figure 3 shows the first negative electrode active material layer (22A) and the second negative electrode active material layer (22B), and also demonstrates the high porosity of the second negative electrode active material layer (22B). Figure 3, along with the teaching of Hiroki that the second negative electrode active material layer has a relatively high porosity compared to the first negative electrode active material layer due to ceramic particles entering the gaps between the graphite particles and forming voids in the second negative electrode active material layer (¶ [0008], Ln. 69-72), teaches that the second negative electrode active material layer (22B) has a lower mass density per unit volume than the first negative electrode active material layer (22A).
Regarding claim 5, Hiroki in view of Tamaki and Katsushi teaches all of the limitations of claim 1 above, and Hiroki further teaches that the thickness of the first negative electrode active material layer is 88-111 µm (¶ [0041], Ln. 368-370)) and that the ratio of the thickness (t2) of the second negative electrode active material layer (22B) to the thickness (t1) of the first negative electrode active material layer (22A) is 0.1<(t2/t1)<0.5 (¶ [0039], Ln. 354-355), resulting in a preferred range for the thickness of the second negative electrode active material layer (22B) of 8.8 µm to 55.5 µm, overlapping the claimed range of 10 µm to 40 µm. In the case where the claimed ranges "overlap or lie inside ranges disclosed by the prior art" a prima facie case of obviousness exists (MPEP 2144.05 (I)).
Regarding claim 8, Hiroki teaches a non-aqueous secondary battery including a positive electrode, the negative electrode previously referenced, and an electrolyte solution (¶ [0007], Ln. 49-50). Therefore, Hiroki in in view of Tamaki and Katsushi teaches a non-aqueous secondary battery comprising a negative electrode meeting the limitations of claim 1.
Regarding claims 9-10, Hiroki in view of Tamaki and Katsushi teaches all of the limitations of claim 1 above, including voids formed in the second negative electrode active material layer (22B) by organic hollow particles having an outer shell made of a thermoplastic resin, which shrinks during the vacuum drying step to form voids. Therefore, voids in the second negative electrode active material layer having a diameter of 3 µm or more would include resin fragment in deformed form due to the vacuum drying step. Similarly, as the organic hollow particles are not used to form voids in the first negative electrode active material layer, the first negative electrode active material layer would not include a resin fragment.
Regarding claim 11, Hiroki in view of Tamaki and Katsushi teaches all of the limitations of claim 1 above, including a porous second negative electrode active material layer (22B). As the second negative electrode active material layer has a high porosity, at least one void having a diameter of 3 µm or more will have an opening at the surface of the layer wherein a width of the opening is smaller than the internal width of the void.
Regarding claim 12, Hiroki in view of Tamaki and Katsushi teaches all of the limitations of claim 1 above. Hiroki further teaches that the diameter of the ceramic particles is “d3” and satisfies the formula d3/d2≤0.1 (¶ [0028], Ln. 263-264). Hiroki teaches that this relationship is satisfied in order for ceramic particles to enter gaps between graphite particles and form voids. Hiroki does not expressly teach that the voids have a diameter of 10-30 µm.
Katsushi teaches that the diameter of the organic hollow particles is 0.1-50 µm, and more preferably 1.0-35 µm (¶ [0028], Ln. 348-350). Katsushi teaches that when the diameter is within this range, the voids may be uniformly dispersed and the battery maintains good cycle characteristics (¶ [0028], Ln. 350-355).
It would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, to include voids having a diameter within 1.0-35 µm, overlapping the claimed range of 10-30 µm, based on the teachings of Katsushi. In the case where the claimed ranges "overlap or lie inside ranges disclosed by the prior art" a prima facie case of obviousness exists (MPEP 2144.05(I)). One of ordinary skill in the art would recognize that, in applying the void-forming process of Katsushi, the void diameters included would be the void diameters taught by the reference rather than the void diameters taught by a separate process, such as the ceramic particles. In applying the process taught by Katsushi, the void particle diameters overlap the claimed range. One of ordinary skill in the art would be motivated to include void diameters within this range using the process taught by Katsushi in order form uniformly dispersed voids and maintain good cycle characteristics of the battery.
Claims 1, 3-6, and 8-12 are rejected under 35 U.S.C. 103 as being unpatentable over Huang, et al. (US 2021/0111410 A1) in view of Katsushi, et al. (WO 2016208480 A1), as evidenced by Ballisteri, A., et al. Thermal Decomposition of Acrylonitrile Copolymers Investigated by Direct Pyrolysis in the Mass Spectrometer Die Makromolekulare Chemie: Macromolecular Chemistry and Physics, Vol 180, no. 12 (1979), pp. 2835-2842, and further in view of Tamaki, et al. (US PGPub 2013/0004845 A1, cited on IDS).
Regarding claims 1 and 6, Huang teaches a negative electrode plate including a first negative electrode active substance layer disposed on a negative electrode current collector (substrate) and a second negative electrode active substance layer disposed on the first negative electrode active substance layer (¶ [0011], Ln. 1-7). Huang teaches that the average grain size of the first negative electrode active substance is 11-20 µm, within the claimed range of more than 10 µm and no more than 20 µm, and the average grain size of the second negative electrode active substance is 1-10 µm, overlapping the claimed range of 4-7 µm (¶ [0017], Ln. 1-11). In the case where the claimed ranges "overlap or lie inside ranges disclosed by the prior art" a prima facie case of obviousness exists (MPEP 2144.05(I)). Additionally, Huang teaches that the porosity of the second negative electrode active substance layer is greater than the porosity of the first negative electrode active substance layer (¶ [0023], Ln. 1-4). Huang teaches that a higher porosity in the second layer is conducive to the infiltration of an electrolyte to the electrode plate and the transmission of lithium ions (¶ [0063], Ln. 6-9).
Huang does not expressly teach that the second negative electrode active substance layer includes a thermoplastic resin that is degradable in an oxygen-containing atmosphere at a temperature of 200 °C or more.
Katsushi teaches a negative electrode for a nonaqueous secondary battery wherein the negative electrode includes a negative electrode active material, a negative electrode binder, and organic hollow particles having an outer shell made of a thermoplastic resin (¶ [0006], Ln. 60-62). Katsushi teaches that the organic hollow particles introduce voids to the negative electrode active material layer (¶ [0015], Ln. 142-144). Katsushi teaches a process of applying the negative electrode slurry to a current collector, drying, and pressing, and provides a vacuum drying temperature of 120 °C (¶ [0109], Ln. 1450-1454). Katsushi further teaches that including organic hollow particles in the slurry for the negative electrode results in a secondary battery with excellent cycle characteristics (¶ [0012], Ln 116-119). The particle size of the organic hollow particles is preferably 0.1-50 µm, more preferably 1.0-35 µm (¶ [0028], Ln. 348-349). The thermoplastic resin is formed by polymerization of a polymerizable monomer component and a crosslinking agent (¶ [0039], Ln. 507-510). The polymerizable monomer is preferably a nitrile-based monomer such as acrylonitrile or methacrylonitrile (¶ [0040], Ln. 516, 521-522) and further includes a monomer other than the nitrile monomer such as a (meth)acrylic acid ester monomer, a carboxyl group-containing monomer, a vinyl ester monomer, or an acrylamide monomer (¶ [0043], Ln. 562-565). Ballisteri teaches that the thermal decomposition of pendant ester groups in methyl acrylate and methyl methacrylate copolymers occurs at 200-260 °C. Additionally, Ballisteri teaches that polyacrylonitrile decomposition fragments are typically detected in the 240-300 °C temperature range (pg. 2835). Based on these teachings, one of ordinary skill in the art would understand that the thermal degradation temperature of the thermoplastic resin of Katsushi is at a temperature above 200 °C.
It would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, to modify the second negative electrode active substance layer of Huang to include organic hollow particles to form voids in the active material layer as taught by Katsushi. As Huang targets a second negative electrode active substance layer having a higher porosity, one of ordinary skill in the art would find it obvious to apply a void-forming process to the layer in order to control the overall porosity. One would be motivated to use organic hollow particles as taught by Katsushi in order to produce a secondary battery with excellent cycle characteristics. In applying the teachings of Katsushi, one of ordinary skill in the art would find it obvious to use organic hollow particles with a size of 1.0-35 µm, forming voids having diameters largely overlapping the claimed range of 3 µm or more. In the case where the claimed ranges "overlap or lie inside ranges disclosed by the prior art" a prima facie case of obviousness exists (MPEP 2144.05(I)). Additionally, in applying the void-forming process of Katsushi using organic hollow particles having a thermoplastic resin shell, one of ordinary skill in the art would find it obvious to apply the vacuum drying temperature of Katsushi. As Huang does not expressly teach the temperature at which the electrode is dried, one of ordinary skill in the art would find it obvious to look to the teachings of Katsushi. Thus, it would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, to dry the electrode layer of Huang in view Katsushi at a similar temperature of 120 °C, based on the similarities in processing and common temperatures for drying. In the step of drying the negative electrode substance layers, the thermoplastic resin shell of the organic hollow particle would shrink, forming voids.
Huang is silent to the number density of voids having a diameter of 3 µm or more per mm2 unit area in a transverse cross section parallel to the thickness direction. Therefore, the reference does not expressly teach that the first negative electrode active material layer has a number density of voids having a diameter of 3 µm or more per unit area of less than 200/mm2 and the second negative electrode active material layer has a number density of voids having a diameter of 3 µm or more per unit area of from 200/mm2 to 1500/mm2.
It would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, to adjust the number density of voids having a diameter of 3 µm or more per unit area to less than 200/mm2 in the first negative electrode active substance layer and to adjust the number density of voids having a diameter of 3 µm or more per unit area to 200-1500/mm2 in the second negative electrode active substance layer through routine optimization. As taught by Huang, having a higher porosity in the second active substance layer is conducive to the infiltration of an electrolyte to the electrode plate and the transmission of lithium ions. Additionally, it is well-known in the art that a low porosity of active material results in higher energy density. Based on the teachings of Huang in view of Katsushi, it would be obvious to adjust the amount of organic hollow particles used in the second active material layer in order to adjust the number of voids. It would be obvious to one ordinary skill in the art to optimize the porosity of the negative electrode active substance layer in order to promote the transmission of lithium ions while maintaining a high energy density of the battery.
Huang is silent to teach the mass density per unit volume of the negative electrode and therefore, does not expressly teach that the mass density per unit volume of the negative electrode active material layer is 1.2 g/cm3 or more.
Tamaki teaches a lithium-ion battery comprising a cathode and an anode, wherein the anode has at least two layers: a collector-side active material layer (24a; first active material layer) provided on the anode collector; and a surface-side active material layer (24b; second active material layer) provided on the collector-side active material layer (¶ [0013], Ln. 1-9). The collector-side active material layer (24a; first active material layer) and the surface-side active material layer (24b; second active material layer) are constructed of an anode active material (21) consisting of carbon material (¶ [0053], Ln. 8-9). The specific surface area of the anode active material in the surface-side active material layer (24b; second active material layer) is greater than the specific surface area of the anode active material in the collector-side active material layer (24a; first active material layer) (¶ [0053], Ln. 11-15) and, as shown in Figure 5, the particle size of the anode active material in the surface-side active material layer (24b; second active material layer) is smaller than the particle size of the anode active material in the collector-side active material layer (24a; first active material layer). Tamaki further teaches that the density of the active material layer is approximately 1.0-1.5 g/cm3 (¶ [0062], Ln. 7-10). Specifically, examples 2-1 – 2-6 and 4-1 – 4-6 teach a density of 1.4 g/cm3 (Table 1, Examples 2-1 – 2-6, 4-1 – 4-6). The density is adjusted during the pressing process (¶ [0063], Ln. 20-23) and Tamaki teaches that a density of the active material layers in this range allows for retention of electrolyte (¶ [0062], Ln. 6-7).
It would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, to modify the negative electrode of Huang to have a mass density per unit volume between 1.0 and 1.5 g/cm3, such as 1.4 g/cm3, as taught by Tamaki, meeting the limitations of claims 1 and 6. The density adjustment could be made during the compression of the negative electrode. One would be motivated to adjust the density within this range in order to allow for adequate retention of the electrolyte within the electrode.
Regarding claim 3, Huang in view of Katsushi and Tamaki teaches all of the limitations of claim 1 above. Huang further teaches that the BET specific surface area of the first negative electrode active substance may be 1-3 m2/g while the BET specific surface area of the second negative electrode active substance may be 4-8 m2/g (BET specific surface area of the second active material particles is more than a BET specific surface area of the first active material particles) (¶ [0019], Ln. 10-19).
Regarding claim 4, Huang in view of Katsushi and Tamaki teaches all of the limitations of claim 1 above. Additionally, Huang teaches that the mass density per unit volume of the second negative electrode active substance layer is less than the mass density per unit volume of the first negative electrode active substance layer, as a higher porosity would result in a lower density. The teaching of Huang that the second negative electrode active substance layer has a higher porosity compared to the first negative electrode active substance layer teaches that the second negative electrode active substance layer has a lower mass density per unit volume than the first negative electrode active substance layer.
Regarding claim 5, Huang in view of Katsushi and Tamaki teaches all of the limitations of claim 1 above. Huang further teaches that the thickness of the second negative electrode active substance layer ranges from 20-150 µm, overlapping the claimed range of 10-40 µm (¶ [0021], Ln. 1-4). ). In the case where the claimed ranges "overlap or lie inside ranges disclosed by the prior art" a prima facie case of obviousness exists (MPEP 2144.05(I)).
Regarding claim 8, Huang in view of Katsushi and Tamaki teaches a negative electrode meeting all of the limitations of claim 1 above. Huang further teaches a secondary battery including the negative electrode above (¶ [0028], Ln. 1-4).
Regarding claims 9-10, Huang in view of Katsushi and Tamaki teaches all of the limitations of claim 1 above, including voids formed in the second negative electrode substance material layer by organic hollow particles having an outer shell made of a thermoplastic resin, which shrinks during the vacuum drying step to form voids. Therefore, voids in the second negative electrode active material layer having a diameter of 3 µm or more would include resin fragment in deformed form due to the vacuum drying step. Similarly, as the organic hollow particles are not used to form voids in the first negative electrode active substance layer, the first negative electrode active substance layer would not include a resin fragment.
Regarding claim 11, Huang in view of Katsushi and Tamaki teaches all of the limitations of claim 1 above, including a second negative electrode active substance layer having a higher porosity. As the second negative electrode active substance layer has a high porosity, at least one void having a diameter of 3 µm or more will have an opening at the surface of the layer wherein a width of the opening is smaller than the internal width of the void.
Regarding claim 12, Huang in view of Katsushi and Tamaki teaches all of the limitations of claim 1 above. Huang does not expressly teach the diameter of the pores in the second negative electrode active substance layer, and therefore does not expressly teach that the voids have a diameter of 10-30 µm.
Katsushi teaches that the diameter of the organic hollow particles is 0.1-50 µm, and more preferably 1.0-35 µm (¶ [0028], Ln. 348-350). Katsushi teaches that when the diameter is within this range, the voids may be uniformly dispersed and the battery maintains good cycle characteristics (¶ [0028], Ln. 350-355).
It would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, to include voids having a diameter within 1.0-35 µm, overlapping the claimed range of 10-30 µm, based on the teachings of Katsushi. In the case where the claimed ranges "overlap or lie inside ranges disclosed by the prior art" a prima facie case of obviousness exists (MPEP 2144.05(I)). One of ordinary skill in the art would recognize that, in applying the void-forming process of Katsushi, the void diameters included would be the void diameters taught by the reference. In applying the process taught by Katsushi, the void particle diameters overlap the claimed range. One of ordinary skill in the art would be motivated to include void diameters within this range using the process taught by Katsushi in order form uniformly dispersed voids and maintain good cycle characteristics of the battery.
Response to Arguments
Response-Claim Rejections – 35 U.S.C. 103
In light of Applicant’s amendment to claim 1, the previous rejection of claim 1 under 35 U.S.C. 103 as being unpatentable over Hiroki, et al. (JP 2020095853 A), and further in view of Tamaki, et al. (US PGPub 2013/0004845 A1, cited on IDS) and Katsushi, et al. (WO 2016208480 A1), as evidenced by Ballisteri, A., et al. Thermal Decomposition of Acrylonitrile Copolymers Investigated by Direct Pyrolysis in the Mass Spectrometer Die Makromolekulare Chemie: Macromolecular Chemistry and Physics, Vol 180, no. 12 (1979), pp. 2835-2842 is modified above. Any arguments with respect to the reference that are still deemed valid will be addressed herein. The Applicant argues that Katsushi does not teach or suggest that the organic hollow particles shrink to form voids, that applying the void-forming process of Katsushi to the electrode of Hiroki would render Hiroki unsatisfactory for its intended purpose, and that Hiroki does not teach the claimed second average particle size. These arguments have been fully considered but they are not persuasive.
With respect to the argument, see page 6 of the remarks filed August 20, 2026, that Katsushi does not teach or suggest that the organic hollow particles shrink to form voids, this argument is not persuasive. The Applicant argues that the organic hollow particles of Katsushi are heat-expanded particles rather than capsules that shrink. While it is acknowledged that Katsushi teaches that the organic hollow particles are formed by thermally expanding microspheres composed of a shell made of thermoplastic resin (¶ [0037], Ln. 482-485), after mixing with the active material and drying at approximately 120°C, one of ordinary skill in the art would recognize that the thermoplastic resin will deform, shrinking to form voids. Katsushi teaches the formation of the organic hollow particles using heat expandable microspheres and then subsequently teaches mixing the organic hollow particles with graphite, CMC, and SBR to form a slurry which is coated on a current collector and dried at 120 °C (Example 1). Similarly, page 15 of the instant specification teaches that outer shell of the capsule shaped particles includes a thermoplastic resin, forming a thermally expandable microcapsule which is expanded prior to mixing with active material, binder, solvent, and conductive material, or the like. Thus, the expanded microspheres containing a thermoplastic resin shell of Katsushi will shrink during the vacuum drying step of the process in the same manner as the instant application.
With respect to the argument, see pages 6-8 of the remarks, that applying the void-forming process of Katsushi to the electrode of Hiroki would render Hiroki unsatisfactory for its intended purpose, this argument is not persuasive. The Applicant argues that because Hiroki teaches the hardness of the ceramic particles attributes to pore formation, the organic hollow particles of Katsushi would change the principle of operation under which the second negative electrode active material of Hiroki was designed to operate. However, Katsushi teaches a separate void-forming process. As detailed in the office action above, the void-forming process of Katsushi may be substituted for the void-forming process of Hiroki, which is satisfactory for the intended purpose of forming voids in the negative electrode layer. The office action does not imply that ceramic particles and thermoplastic resin organic hollow particles are identical but rather argues that it would be obvious to use a different known void-forming process in the making of the negative electrode layer, such as the process taught by Katsushi.
Regarding the argument, see pages 8-9 of the remarks, that Hiroki does not teach the claimed second average particle size, this argument is not persuasive. While it is acknowledged that Hiroki does not expressly teach that the second average particle size is 4 µm to 7 µm, the reference does teach a second average particle size of more than 8 µm and less than 34 µm, falling very close to the claimed range. Thus, one of ordinary skill in the art would find it obvious to try a particle size slightly outside the taught range. Given a teaching that the particle size may be more than 8 µm and less than 34 µm, one of ordinary skill in the art would find it obvious to try 7 µm with a reasonable expectation of success. A prima facie case of obviousness exists where the claimed ranges or amounts do not overlap with the prior art but are merely close (MPEP 2144.05(I)).
Conclusion
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/SARAH J JACOBSON/Examiner, Art Unit 1785
/MARK RUTHKOSKY/Supervisory Patent Examiner, Art Unit 1785
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