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 .
Priority
Receipt is acknowledged of certified copies of papers required by 37 CFR 1.55.
Information Disclosure Statement
The information disclosure statements (IDS) submitted on 4/17/24, 5/20/25, and 9/2/25 were filed. The submission is in compliance with the provisions of 37 CFR 1.97. Accordingly, the information disclosure statements have been considered by the examiner.
Drawings
The drawings were received on 4/17/24. These drawings are acceptable.
Specification
The title of the invention is not descriptive. A new title is required that is clearly indicative of the invention to which the claims are directed.
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.
This application currently names joint inventors. In considering patentability of the claims the examiner presumes that the subject matter of the various claims was commonly owned as of the effective filing date of the claimed invention(s) absent any evidence to the contrary. Applicant is advised of the obligation under 37 CFR 1.56 to point out the inventor and effective filing dates of each claim that was not commonly owned as of the effective filing date of the later invention in order for the examiner to consider the applicability of 35 U.S.C. 102(b)(2)(C) for any potential 35 U.S.C. 102(a)(2) prior art against the later invention.
Claims 1-2 and 4-10 are rejected under 35 U.S.C. 103 as being unpatentable over WO 2015/041167 A1 (“WO’167”) in view of WO 2021/023137 A1 (“WO’137”).
As to Claim 1:
WO’167 discloses a secondary battery comprising a positive electrode, a negative electrode including a negative-electrode active-material layer, and an electrolytic solution including an electrolyte salt. In Example 1, WO’167 prepares a positive electrode by applying a positive-electrode mixture containing a lithium-containing positive-electrode active material to an aluminum-foil current collector. It also prepares a negative electrode by applying a negative-electrode mixture to a copper-foil current collector, thereby forming negative-electrode mixture layers on both sides of the current collector (WO’167, p. 18). The positive and negative electrodes are stacked with separators, placed in a battery container, and impregnated with a nonaqueous electrolyte solution to obtain a nonaqueous secondary battery (WO’167, p. 19).
WO’167 discloses that the negative-electrode active-material layer includes a carbon material. In particular, the negative-electrode mixture of Example 1 contains 97.5 parts by mass graphite as the negative-electrode active material, together with styrene-butadiene rubber and carboxymethyl cellulose as binders (WO’167, p. 18). WO’167 also more generally identifies natural graphite, artificial graphite, expanded graphite, and other carbonaceous materials as suitable negative-electrode active materials (WO’167, pp. 8–10).
WO’167 discloses that the negative-electrode active-material layer has a thickness greater than or equal to 30 micrometers and less than or equal to 100 micrometers. Specifically, the negative-electrode mixture layer in Example 1 has a thickness of 59 micrometers per side, which falls within the claimed range (WO’167, p. 18).
WO’167 discloses that the negative-electrode active-material layer has a volume density greater than or equal to 1.4 grams per cubic centimeter and less than or equal to 2 grams per cubic centimeter. Specifically, the negative-electrode mixture layer in Example 1 has a density of 1.5 grams per cubic centimeter, which falls within the claimed range (WO’167, p. 18).
WO’167 discloses an electrolytic solution including an electrolyte salt. The electrolyte solution of Example 1 contains LiPF₆ at a concentration of 1.2 mol/L in a mixed nonaqueous solvent containing ethylene carbonate, diethyl carbonate, ethyl methyl carbonate, and dimethyl carbonate (WO’167, p. 19). WO’167 also generally teaches dissolving a lithium salt in a nonaqueous solvent to form the electrolyte solution (WO’167, pp. 16–17).
However, WO’167 does not disclose that the electrolyte salt includes an imide anion satisfying at least one of the first through fourth imide-anion structures recited in claim 1. Although WO’167 lists lithium bis(trifluoromethanesulfonyl)imide, LiN(CF₃SO₂)₂, as one possible electrolyte salt (WO’167, p. 17), that salt contains only one negatively charged nitrogen and does not disclose the claimed Formula (1), which requires two negatively charged nitrogen atoms connected through the recited W groups.
WO’137 discloses a lithium-ion battery having an electrolyte containing a Formula I imide-type lithium salt (WO’137, pp. 2–4). Among the expressly disclosed lithium salts is:
FSO₂N⁻(Li⁺)SO₂N⁻(Li⁺)SO₂F(WO’137, p. 4).
Upon dissociation, this salt provides the imide dianion:
FSO₂–N⁻–SO₂–N⁻–SO₂F.
This anion satisfies Formula (1) of claim 1 because:
R1 and R2 are each fluorine;
W1, W2, and W3 are each sulfonyl groups; and
the resulting structure is F–SO₂–N⁻–SO₂–N⁻–SO₂–F.
Thus, WO’137 expressly teaches an electrolyte salt whose imide anion falls within the first imide anion represented by Formula (1). WO’137 further teaches that these imide-type salts have good thermal stability and ionic conductivity, low binding energy, and high dissociation capability, and that their use improves battery cycle performance, rate performance, safety, and low-temperature discharge performance (WO’137, pp. 3–4). WO’137 permits the negative-electrode active material to include graphite and related carbon materials (WO’137, p. 6), and its examples report improved battery properties from electrolytes containing the disclosed imide-type lithium salts (WO’137, p. 10).
WO’167 and WO’137 are analogous arts because both concern nonaqueous lithium secondary batteries having positive and negative electrodes and an electrolyte containing a lithium salt. WO’167 seeks a high-capacity battery having favorable high-current charge-and-discharge load characteristics (WO’167, p. 2), while WO’137 addresses electrolyte salts for improving the cycle, rate, safety, and low-temperature performance of lithium-ion batteries (WO’137, pp. 2–4). The references therefore are in the same field of endeavor and address related battery-performance concerns.
It would have been obvious to a person skilled in the art before the effective filing date of the instant application to modify the electrolyte of WO’167 to include the imide lithium salt FSO₂N⁻(Li⁺)SO₂N⁻(Li⁺)SO₂F disclosed by WO’137, either by replacing at least a portion of WO’167’s LiPF₆ or by supplementing the LiPF₆-containing electrolyte. WO’137 expressly teaches that this class of imide lithium salts provides high dissociation capability and ionic conductivity and improves cycle performance, rate performance, safety, and low-temperature discharge performance (WO’137, pp. 3–4). Those stated advantages would have provided a reason to use the WO’137 salt in WO’167’s battery, which seeks favorable high-current charge-and-discharge characteristics (WO’167, p. 2). WO’137’s express use of these salts in lithium-ion batteries, including batteries having graphite negative-electrode active materials, also would have provided a reasonable expectation that the modification would successfully produce a functioning secondary battery (WO’137, pp. 2–6, 10). The resulting battery would include each limitation of claim 1.
As to Claim 2:
WO’167 in view of WO’137 discloses the secondary battery recited in claim 1, including the positive electrode, graphite-containing negative-electrode active-material layer having a thickness of 59 micrometers and a volume density of 1.5 grams per cubic centimeter, and an electrolyte modified to include the Formula (1) imide anion disclosed by WO’137, for the reasons set forth in the rejection of claim 1.
WO’167 further discloses that the negative electrode includes a styrene-butadiene rubber, as additionally required by claim 2. Specifically, in Example 1, WO’167 prepares the negative-electrode mixture using 97.5 parts by mass graphite as the negative-electrode active material, 1.5 parts by mass styrene-butadiene rubber (“SBR”) as a binder, and 1 part by mass carboxymethyl cellulose as a thickener. The resulting mixture is applied to a copper-foil current collector to form the negative-electrode active-material layers (WO’167, p. 18). Accordingly, WO’167 expressly discloses the additional styrene-butadiene-rubber limitation of claim 2.
As to Claim 4:
WO’167 in view of WO’137 discloses the secondary battery according to claim 1, including the positive electrode, graphite-containing negative-electrode active-material layer having a thickness of 59 micrometers and a volume density of 1.5 grams per cubic centimeter, and an electrolyte modified to include the Formula (1) imide anion disclosed by WO’137, for the reasons set forth in the rejection of claim 1.
WO’167 further discloses that the electrolyte salt includes a light-metal ion as a cation, as additionally required by claim 4. WO’167 expressly describes its nonaqueous electrolyte as a solution in which a lithium salt is dissolved in a nonaqueous solvent (WO’167, p. 16). WO’167 explains that the lithium salt dissociates in the nonaqueous solvent to form Li⁺ ions and identifies LiPF₆ and other lithium salts as suitable electrolyte salts (WO’167, p. 17). Example 1 specifically employs LiPF₆ at a concentration of 1.2 mol/L in the electrolyte solution (WO’167, p. 19). Thus, WO’167’s electrolyte salt includes lithium ions as light-metal cations.
As to Claim 5:
WO’167 in view of WO’137 discloses the secondary battery according to claim 4, including an electrolyte salt having a light-metal ion as a cation, for the reasons set forth in the rejections of claims 1 and 4.
WO’167 further discloses that the light-metal ion includes a lithium ion, as additionally required by claim 5. WO’167 describes its nonaqueous electrolyte as a solution in which a lithium salt is dissolved in a nonaqueous solvent (WO’167, p. 16). WO’167 expressly states that the lithium salt dissociates in the nonaqueous solvent to form Li⁺ ions and identifies LiPF₆ and other lithium salts as suitable electrolyte salts (WO’167, p. 17). Example 1 specifically employs LiPF₆ at a concentration of 1.2 mol/L in the electrolyte solution (WO’167, p. 19). Thus, the light-metal cation in WO’167 is expressly a lithium ion.
As to Claim 6:
WO’167 in view of WO’137 discloses the secondary battery according to claim 1, including the positive electrode, the graphite-containing negative-electrode active-material layer having a thickness of 59 micrometers and a volume density of 1.5 grams per cubic centimeter, and an electrolyte modified to include the Formula (1) imide anion disclosed by WO’137, for the reasons set forth in the rejection of claim 1.
WO’167 further discloses controlling the content of the electrolyte salt in the electrolytic solution. WO’167 teaches that increasing lithium-salt concentration increases electrical conductivity but also proportionally increases electrolyte viscosity, such that the lithium-salt concentration and nonaqueous solvent should be balanced (WO’167, p. 16). WO’167 consequently provides a preferred lithium-salt concentration of 0.5–1.5 mol/L and a more preferred concentration of 0.9–1.25 mol/L (WO’167, p. 17). Example 1 employs LiPF₆ at 1.2 mol/L (WO’167, p. 19).
However, WO’167 does not expressly disclose its electrolyte-salt content on the claimed mol/kg basis. WO’167 also does not disclose the inherited limitation of claim 1 requiring an electrolyte salt containing an imide anion satisfying at least one of Formulas (1)–(4). Although WO’167 identifies LiN(CF₃SO₂)₂ as a possible lithium salt (WO’167, p. 17), that salt has only one negatively charged nitrogen and does not satisfy Formula (1), which requires two negatively charged nitrogen atoms connected through the recited W groups.
WO’137 discloses an electrolyte salt satisfying the Formula (1) imide-anion limitation and an overlapping electrolyte-salt content. In particular, WO’137 expressly discloses:
FSO₂N⁻(Li⁺)SO₂N⁻(Li⁺)SO₂F(WO’137, p. 4).
This salt provides the imide dianion FSO₂–N⁻–SO₂–N⁻–SO₂F, which satisfies Formula (1) because R1 and R2 are fluorine and W1, W2, and W3 are sulfonyl groups. WO’137 further discloses that the mass of its Formula I imide lithium salt is 5%–25% of the total mass of the electrolyte (WO’137, p. 4).
The disclosed salt FSO₂N⁻(Li⁺)SO₂N⁻(Li⁺)SO₂F has the molecular formula Li₂F₂N₂O₆S₃ and a formula weight of approximately 272.1 g/mol. Accordingly, a concentration of 10 mass%, which falls within WO’137’s disclosed 5%–25% range, corresponds to:
100
g salt
272.1
g/mol
÷
1
kg electrolyte
≈
0.368
mol/kg
.
The resulting concentration of approximately 0.368 mol/kg falls within the claimed range of 0.2–2 mol/kg. More generally, the portion of WO’137’s 5%–25% range above approximately 5.44 mass% corresponds to at least 0.2 mol/kg, while 25 mass% corresponds to approximately 0.919 mol/kg. Thus, a substantial portion of WO’137’s disclosed concentration range falls within the range of claim 6. This calculation is based on the chemical formula and electrolyte mass-percentage range expressly disclosed by WO’137 rather than official notice concerning an unrecited electrolyte concentration.
WO’137 also supplies a reason for using the disclosed concentration range. It teaches that an excessively low concentration of the Formula I salt produces an insufficient Li⁺ concentration and fails to significantly improve conductivity, cycle performance, and rate performance. Conversely, an excessively high concentration excessively increases electrolyte viscosity and impairs cycle and low-temperature performance. WO’137 states that using 5%–25% Formula I salt improves cycle, rate, and low-temperature discharge performance (WO’137, p. 4).
It would have been obvious to a person skilled in the art before the effective filing date of the instant application to modify the electrolyte of WO’167 by replacing at least a portion of WO’167’s LiPF₆ with the Formula I imide lithium salt FSO₂N⁻(Li⁺)SO₂N⁻(Li⁺)SO₂F disclosed by WO’137 and to use that salt at a concentration within WO’137’s disclosed 5%–25% range that corresponds to 0.2–2 mol/kg, such as 10 mass% or approximately 0.368 mol/kg. WO’167 expressly teaches controlling lithium-salt concentration to balance conductivity and viscosity (WO’167, pp. 16–17), and WO’137 expressly teaches that its 5%–25% imide-salt range avoids insufficient conductivity at low concentration and excessive viscosity at high concentration while improving cycle, rate, and low-temperature performance (WO’137, p. 4). WO’137’s express use and testing of its Formula I salts in lithium-ion batteries would have provided a reasonable expectation that the modification would successfully produce a functioning secondary battery (WO’137, pp. 8–10). The resulting secondary battery would include every limitation of claim 6.
As to Claim 7:
WO’167 in view of WO’137 discloses the secondary battery according to claim 1, including the positive electrode, the graphite-containing negative-electrode active-material layer having a thickness of 59 micrometers and a volume density of 1.5 grams per cubic centimeter, and an electrolyte modified to include the Formula (1) imide anion disclosed by WO’137, for the reasons set forth in the rejection of claim 1.
WO’167 discloses that the electrolytic solution further includes lithium hexafluorophosphate. Specifically, WO’167 identifies LiPF₆ as a suitable lithium salt that dissociates in the nonaqueous solvent to form Li⁺ ions (WO’167, p. 17). Example 1 expressly employs LiPF₆ at a concentration of 1.2 mol/L in the electrolytic solution (WO’167, p. 19). Thus, WO’167 discloses LiPF₆ containing a lithium ion and a corresponding hexafluorophosphate ion.
However, WO’167 does not disclose an electrolyte salt having one of the multi-nitrogen imide anions required by claim 1. Accordingly, WO’167 also does not disclose an electrolyte containing the claimed Formula (1) imide salt together with LiPF₆ such that:
the sum of the content of the cations of the imide salt and the content of the lithium ions from LiPF₆ is 0.7–2.2 mol/kg; and
the molar ratio of hexafluorophosphate ions to imide anions is 13–6000 mole percent.
Although WO’167 identifies LiN(CF₃SO₂)₂ as a possible lithium salt (WO’167, p. 17), that salt contains only one negatively charged nitrogen and does not satisfy Formula (1), which requires two negatively charged nitrogen atoms connected through the recited W groups. WO’167 also does not expressly provide the claimed mol/kg sum or PF₆⁻-to-imide-anion molar ratio.
WO’137 discloses an electrolyte salt including lithium cations and an imide anion satisfying Formula (1). Specifically, WO’137 discloses:
FSO₂N⁻(Li⁺)SO₂N⁻(Li⁺)SO₂F(WO’137, p. 4).
This salt provides two Li⁺ cations and the imide dianion FSO₂–N⁻–SO₂–N⁻–SO₂F. The imide dianion satisfies Formula (1) because R1 and R2 are fluorine and W1, W2, and W3 are sulfonyl groups. WO’137 teaches using its Formula I imide lithium salt at 5%–25% of the total mass of the electrolyte (WO’137, p. 4).
WO’137 further expressly teaches adding an appropriate amount of LiPF₆ to an electrolyte containing the Formula I imide lithium salt. WO’137 explains that LiPF₆ alleviates corrosion of the positive-electrode current collector caused by the Formula I salt and provides an LiPF₆ content of 0%–10% of the total mass of the electrolyte (WO’137, p. 5). Thus, WO’137 expressly teaches an electrolyte containing both the claimed imide salt and LiPF₆ and provides a reference-based reason for combining the two salts.
A composition containing 10 mass% FSO₂N⁻(Li⁺)SO₂N⁻(Li⁺)SO₂F and 2 mass% LiPF₆ falls within the respective 5%–25% and 0%–10% ranges disclosed by WO’137. The quantitative conditions resulting from this expressly taught combination are as follows.
The Formula (1) salt has the molecular formula Li₂F₂N₂O₆S₃ and a formula weight of approximately 272.1 g/mol. At 10 mass% of the total electrolyte:
100
g
272.1
g
/
m
o
l
=
0.368
m
o
l
/
k
g
of Formula (1) salt is present. Because each formula unit contains two Li⁺ cations and one imide dianion, this provides approximately:
2
0.368
=
0.736
m
o
l
/
k
g
of cations and 0.368 mol/kg of imide anions.
LiPF₆ has a formula weight of approximately 151.9 g/mol. At 2 mass% of the total electrolyte:
20
g
151.9
g
/
m
o
l
=
0.132
m
o
l
/
k
g
of LiPF₆ is present, thereby providing 0.132 mol/kg of lithium ions and 0.132 mol/kg of hexafluorophosphate ions.
The claimed sum of the cation content and the lithium-ion content therefore is:
0.736
+
0.132
=
0.868
m
o
l
/
k
g
,
which falls within the claimed range of 0.7–2.2 mol/kg.
The claimed molar ratio of hexafluorophosphate ions to imide anions is:
0.132
0.368
×
100
=
35.9
m
o
l
e
p
e
r
c
e
n
t
,
which falls within the claimed range of 13–6000 mole percent. These calculations are based on the chemical formulas and concentration ranges expressly disclosed by WO’137 and do not rely on an officially noticed electrolyte composition.
It would have been obvious to a person skilled in the art before the effective filing date of the instant application to modify the LiPF₆-containing electrolyte of WO’167 to further include the Formula I imide lithium salt FSO₂N⁻(Li⁺)SO₂N⁻(Li⁺)SO₂F disclosed by WO’137 and to select the amounts of the two salts from the ranges expressly taught by WO’137, such as 10 mass% Formula I salt and 2 mass% LiPF₆. WO’137 expressly teaches using 5%–25% Formula I salt to improve conductivity, cycle performance, rate performance, and low-temperature performance and adding up to 10% LiPF₆ to alleviate corrosion of the positive-electrode current collector (WO’137, pp. 4–5). Those teachings provide a reference-based reason to use the two salts together and to select their respective amounts. WO’137’s express preparation and testing of lithium-ion batteries containing its imide salts would have provided a reasonable expectation of success (WO’137, pp. 8–10). The resulting electrolyte would have a combined cation content of approximately 0.868 mol/kg and a PF₆⁻-to-imide-anion ratio of approximately 35.9 mole percent, thereby satisfying every limitation of claim 7.
As to Claim 8:
WO’167 in view of WO’137 discloses the secondary battery according to claim 1, including the positive electrode, the graphite-containing negative-electrode active-material layer having a thickness of 59 micrometers and a volume density of 1.5 grams per cubic centimeter, and an electrolyte modified to include the Formula (1) imide anion disclosed by WO’137, for the reasons set forth in the rejection of claim 1.
WO’167 further discloses that the electrolytic solution includes at least one of the electrolyte additives recited in claim 8. Specifically, WO’167 teaches that the electrolytic solution preferably contains a cyclic sulfonic acid ester and identifies 1,3-propane sultone, 1,4-butane sultone, 2,4-butane sultone, and 1,3-butane sultone as suitable cyclic sulfonic acid esters (WO’167, p. 17). Example 1 expressly includes 0.5 mass% 1,3-propane sultone in the electrolytic solution (WO’167, p. 19). Accordingly, WO’167 expressly discloses a sulfonic acid ester, which satisfies at least one of the alternatives recited in claim 8. Example 1 additionally includes 2.0 mass% vinylene carbonate in the electrolytic solution (WO’167, p. 19).
As to Claim 9:
WO’167 in view of WO’137 discloses the secondary battery according to claim 1, including the positive electrode, the graphite-containing negative-electrode active-material layer having a thickness of 59 micrometers and a volume density of 1.5 grams per cubic centimeter, and an electrolyte modified to include the Formula (1) imide anion disclosed by WO’137, for the reasons set forth in the rejection of claim 1.
WO’167 further discloses that the electrolytic solution includes at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium bis(fluorosulfonyl)imide, lithium bis(oxalato)borate, or lithium difluorophosphate, as required by claim 9. Specifically, WO’167 identifies LiPF₆ and LiBF₄ as suitable lithium salts for the electrolytic solution (WO’167, p. 17). Example 1 expressly employs LiPF₆ at a concentration of 1.2 mol/L in the electrolytic solution (WO’167, p. 19). Accordingly, WO’167 expressly discloses lithium hexafluorophosphate, thereby satisfying at least one of the alternative salts recited in claim 9.
As to Claim 10:
WO’167 in view of WO’137 discloses the secondary battery according to claim 1, including the positive electrode, the graphite-containing negative-electrode active-material layer having a thickness of 59 micrometers and a volume density of 1.5 grams per cubic centimeter, and an electrolyte modified to include the Formula (1) imide anion disclosed by WO’137, for the reasons set forth in the rejection of claim 1.
WO’167 further discloses that the secondary battery comprises a lithium-ion secondary battery, as required by claim 10. WO’167 identifies lithium-ion secondary batteries as nonaqueous secondary batteries and explains that such batteries provide high energy density and are used as power sources for portable devices, automobiles, motorcycles, and mobile objects (WO’167, p. 2). WO’167 further expressly refers to the battery of its invention as a “lithium ion secondary battery” and describes cylindrical, prismatic, and soft-package forms for that battery (WO’167, p. 17). In Example 1, the battery includes a lithium-containing positive-electrode active material, a graphite negative-electrode active material, and a nonaqueous LiPF₆ electrolyte, and the electrodes and electrolyte are assembled to obtain the disclosed nonaqueous secondary battery (WO’167, pp. 18–19). Accordingly, WO’167 expressly discloses the additional lithium-ion-secondary-battery limitation of claim 10.
Claim 3 is rejected under 35 U.S.C. § 103 as being unpatentable over WO 2015/041167 A1 (“WO’167”) in view of WO 2021/023137 A1 (“WO’137”), as applied to Claim 1, and further in view of US 2010/0209331 A1 (“US’331”).
As to Claim 3:
WO’167 in view of WO’137 discloses the secondary battery according to claim 1, including the positive electrode, the negative-electrode active-material layer having a thickness of 59 micrometers and a volume density of 1.5 grams per cubic centimeter, and an electrolyte modified to include the Formula (1) imide anion disclosed by WO’137, for the reasons set forth in the rejection of claim 1.
WO’167 further discloses that the carbon material includes graphite, as required by claim 3. Specifically, Example 1 prepares the negative electrode using 97.5 parts by mass graphite as the negative-electrode active material, 1.5 parts by mass SBR as a binder, and 1 part by mass CMC as a thickener. The mixture is applied to a copper-foil current collector and calendered to form a negative-electrode active-material layer having a thickness of 59 micrometers and a density of 1.5 g/cm³ (WO’167, p. 18). WO’167 also generally identifies natural graphite, artificial graphite, and expanded graphite as suitable negative-electrode active materials (WO’167, pp. 8–10).
However, WO’167 does not disclose that the spacing of the graphite (002) plane, measured by X-ray diffractometry, is less than or equal to 0.3372 nanometers. WO’167 also does not disclose the inherited limitation of claim 1 requiring an electrolyte salt having an imide anion satisfying at least one of Formulas (1)–(4). Although WO’167 identifies LiN(CF₃SO₂)₂ as a possible lithium salt (WO’167, p. 17), that salt contains only one negatively charged nitrogen and does not satisfy Formula (1), which requires two negatively charged nitrogen atoms connected through the recited W groups.
WO’137 discloses an electrolyte containing an imide-type lithium salt that supplies the missing electrolyte limitation inherited from claim 1. Specifically, WO’137 expressly identifies the following Formula I lithium salt:
FSO₂N⁻(Li⁺)SO₂N⁻(Li⁺)SO₂F(WO’137, p. 4).
This salt provides the imide dianion FSO₂–N⁻–SO₂–N⁻–SO₂F, which satisfies Formula (1) because R1 and R2 are fluorine and W1, W2, and W3 are sulfonyl groups. WO’137 teaches that its Formula I imide-type lithium salts provide good thermal stability, excellent conductivity, low binding energy between Li⁺ and the imide anion, and a high degree of Li⁺ dissociation, thereby improving cycle, rate, safety, and low-temperature discharge performance (WO’137, pp. 3–4).
US’331 discloses artificial graphite for use as a negative-electrode active material in a lithium-ion secondary battery. US’331 expressly states that its artificial graphite exhibits excellent performance as a negative-electrode material for a lithium-ion secondary battery (US’331, [0018]). US’331 further teaches that the artificial graphite preferably has a mean interlayer distance d₀₀₂ of 0.3365–0.3375 nanometers and, more preferably, 0.3367–0.3372 nanometers, as measured by wide-angle X-ray diffraction (US’331, [0024]). Accordingly, the entire more-preferred range disclosed by US’331 satisfies the claim limitation requiring a graphite (002)-plane spacing of less than or equal to 0.3372 nanometers.
US’331 identifies the interlayer distance d₀₀₂ as the graphite lattice constant and provides an X-ray-diffraction measurement procedure for determining that value (US’331, [0026–28]). Thus, US’331 measures the same graphite structural property recited in claim 3.
US’331 additionally provides a working example of artificial graphite satisfying the claimed upper limit. In Example 1, Artificial Graphite A has an interlayer distance d₀₀₂ of 0.3367 nanometers, as measured by X-ray diffraction, which is less than 0.3372 nanometers (US’331, [0067] and Table 1). Artificial Graphite A is used as the negative-electrode active material in a slurry containing acetylene black and PVDF. The slurry is coated onto copper foil, dried, and press-molded with a roll press to form the negative electrode (US’331, [0068]). US’331 reports that use of Artificial Graphite A as the lithium-ion-secondary-battery negative-electrode material maintains relatively high charge-discharge capacity and utilization even at a high charge-discharge rate of 10C (US’331, [0072]).
WO’167, WO’137, and US’331 are analogous arts because all three references concern lithium-ion secondary batteries. WO’167 concerns a high-capacity lithium-ion secondary battery having improved large-current charge-and-discharge characteristics and uses graphite as the negative-electrode active material (WO’167, pp. 2 and 18). WO’137 concerns improving lithium-ion-battery cycle and rate performance through the lithium salt used in the electrolyte (WO’137, pp. 2–4). US’331 concerns artificial graphite specifically intended for lithium-ion-battery negative electrodes and seeks improved rapid charge-discharge characteristics while maintaining favorable energy density (US’331, [0018, 0024, and 0064]). The references therefore are in the same field of endeavor and address complementary aspects of lithium-ion-battery charge-and-discharge performance.
It would have been obvious to a person skilled in the art before the effective filing date of the instant application to modify the graphite-containing negative-electrode active-material layer of WO’167 by employing the artificial graphite disclosed by US’331, having a (002)-plane interlayer spacing within the more-preferred range of 0.3367–0.3372 nanometers, including Artificial Graphite A having a measured spacing of 0.3367 nanometers, while retaining WO’167’s disclosed active-material-layer thickness and density. US’331 expressly teaches that its graphite is suitable as a negative-electrode active material, can be formed into an electrode by coating a graphite-containing slurry onto copper foil and roll pressing the coating, and maintains favorable capacity and utilization at high charge-discharge rates (US’331, [0018, 0068, and 0072]). These teachings provide a reference-based reason and reasonable expectation of success for using US’331’s artificial graphite in WO’167’s similarly coated and calendered graphite negative electrode to further WO’167’s objective of improved large-current charge-and-discharge characteristics (WO’167, pp. 2 and 18). It further would have been obvious to modify WO’167’s electrolyte to include the Formula I imide lithium salt disclosed by WO’137 for the improved conductivity, cycle, rate, safety, and low-temperature performance expressly taught by WO’137 (WO’137, pp. 3–4). The resulting secondary battery would include graphite having a (002)-plane spacing less than or equal to 0.3372 nanometers and would satisfy every limitation of claim 3.
Conclusion
The prior art made of record and not relied upon is considered pertinent to applicant's disclosure.
CN 112349962 B discloses the lithium salt comprises one or more of compounds represented by formula I, wherein n is an integer of 1 ~ 3, Rf1 and Rf2 is CmF2m + 1, wherein m is an integer of 0 ~ 5, Rf1, Rf2 are the same or different, the group margin of the lithium-ion battery is 85 % ~ 95 %.
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/JIMMY VO/
Primary Examiner
Art Unit 1723
/JIMMY VO/Primary Examiner, Art Unit 1723
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