DETAILED ACTION
Status of the Claims
Applicant’s amendment filed 9 July 2026 is acknowledged. Claim 1 has been amended, claim 5 has been canceled, and claims 1-3, 6, 7, and 11-13 remain pending.
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 .
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.
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.
Claim(s) 1, 2, and 6, 7, and 11-13 is/are rejected under 35 U.S.C. 103 as being unpatentable over Chen et al. (US 2021/0218015, hereinafter “Chen”), in view of Jung et al. (US 2002/0045102, hereinafter “Jung”; listed in the IDS filed 16 December 2022), Park et al. (US 2019/0051940, hereinafter “Park”; listed in the IDS filed 26 December 2023), with evidence by NIH (National Center for Biotechnology Information. "PubChem Compound Summary for CID 8071, 1,2-Dimethoxyethane" PubChem, https://pubchem.ncbi.nlm.nih.gov/compound/1_2-Dimethoxyethane. Accessed 5 April, 2026, NPL), and Pan et al. (CN 109216769 A, hereinafter “Pan”; listed in the IDS filed 30 May 2025; using the attached English machine translation for citations).
Regarding claim 1, Chen teaches an electrolyte solution for a lithium-sulfur battery, comprising:
a lithium nitrate (lithium nitrate (LiNO3), see [0057]);
a borate-based lithium salt (lithium tetrafluoroborate (LiBF4), see [0057]); and
a lithium salt different from the lithium nitrate and the borate-based lithium salt (see [0057]).
Chen teaches one or more solvents (see [0013]), but is silent to a first solvent comprising a heterocyclic compound containing one or more double bonds and any one of an oxygen atom and a sulfur atom,
a second solvent comprising at least one of an ether-based compound, an ester-based compound, an amide-based compound, and a carbonate-based compound,
wherein volume ratio of the first solvent to the second solvent is 1:2.5 to 1:6, and
wherein the first solvent comprises 2-methylfuran, and the second solvent comprises 1,2-dimethoxyethane.
Jung teaches a lithium electrolyte solution which includes at least two groups selected from a weak polar solvent group, a strong polar solvent group, and a lithium protection solvent group (see abstract). The lithium protection solvent can be represented by 2-methyl furan (equated to the claimed first solvent; see [0029]). The weak polar solvent can be represented by 1,2-dimethoxyethane (dimethoxyethane, equated to the claimed second solvent; see [0027]; also see evidence by NIH in section 2.4.2 which cites “1,2-dimethoxyethane as a synonym for “dimethoxyethane”). The lithium protection solvent in combination with a weak polar solvent forms a protective layer providing a stable solid electrolyte interface on the lithium surface resulting in good cyclic efficiency (see [0026]).
In view of Jung’s teachings, it would have been obvious to one of ordinary skill in the art at the time the invention was filed to modify the solution of Chen to include a first solvent comprising a heterocyclic compound containing one or more double bonds and any one of an oxygen atom and a sulfur atom, equated to 2-methylfuran (see [0029]), and a second solvent comprising at least one of an ether-based compound, an ester-based compound, an amide-based compound, and a carbonate-based compound, equated to 1,2-dimethoxyethane (dimethoxyethane, see [0027]; also see evidence by NIH in section 2.4.2 which cites “1,2-dimethoxyethane as a synonym for “dimethoxyethane”), as taught by Jung, because it helps to form a protective layer providing a stable solid electrolyte interface on the lithium surface resulting in good cyclic efficiency.
The combination of Chen and Jung is silent to wherein volume ratio of the first solvent to the second solvent is 1:2.5 to 1:6.
Park teaches an electrolyte for a secondary battery that can comprise a mixed solvent (see [0012]-[0015]), comprising a linear ether (see [0039] for examples) and a cyclic ether (see [0040] for examples) mixed in a volume ratio of 5:95 to 95:5 (see [0012]-[0015] and [0042]). The lithium secondary battery provided with the electrolyte according to the disclosure has an excellent cycle-dependent capacity retention rate, and accordingly, is effective in improving a battery lifespan property (see abstract).
In view of Park’s teachings, it would have been obvious to one of ordinary skill in the art at the time the invention was filed to modify the invention of the combination of Chen and Jung to include wherein volume ratio of the first solvent to the second solvent is 1:2.5 to 1:6, as taught by Park, because it helps produce a battery with an excellent cycle-dependent capacity retention rate and is effective in improving a battery lifespan property.
The combination of Chen, Jung, and Park teaches the borate-based lithium salt (Chen: lithium tetrafluoroborate (LiBF4), see [0057]) and the lithium nitrate (Chen: lithium nitrate (LiNO3), see [0057]), but is silent to wherein a weight ratio of the borate-based lithium salt and to the lithium nitrate is 1:3 to 1:30.
Pan teaches a lithium metal battery electrolyte for a lithium-sulfur battery. Pan teaches that the electrolyte contains a solvent and three salts, wherein lithium salt II is lithium nitrate (LiNO3) (see [0017]) because it suppresses the continuous occurrence of side reactions thereby improving the cycle stability of lithium-sulfur batteries (see [0067]), and lithium salt III is a boron-containing lithium salt which can include lithium tetrafluoroborate (see [0014]) because it can further improve the electrochemical performance of lithium-sulfur batteries (see [0068]). Pan teaches that their mass percentages are lithium salt II 0.1% - 3% and lithium salt III 0.1% - 10% (see [0023]). Pan teaches that lithium-sulfur batteries assembled using their electrolyte improves cycle performance of the battery (see [0008] and [0064]).
In view of Pan’s teachings, it would have been obvious to one of ordinary skill in the art at the time the invention was filed to modify the electrolyte solution of the combination of Chen, Jung, and Park to include wherein a weight ratio of the borate-based lithium salt and to the lithium nitrate is 1:3 to 1:30, because it can help to improve cycle performance of the battery. In the case where the claimed ranges "overlap or lie inside ranges disclosed by the prior art" a prima facie case of obviousness exists. See MPEP §2144.05(I). Furthermore, the Applicant is reminded that where the general conditions of a claim are disclosed in the prior art, it is not inventive to discover the optimum or workable ranges by routine experimentation. See MPEP 2144.05(II)(A).
Regarding claim 2, the combination of Chen, Jung, Park, and Pan teaches wherein the borate-based lithium salt is at least one selected from the group consisting of lithium tetrafluoroborate (LiBF4) and lithium bis(oxalate)borate (LiBOB) (Chen: see [0057]; Pan: see [0014]).
Regarding claim 6, the combination of Chen, Jung, Park, and Pan teaches wherein the lithium salt is LiBr, LiI, LiClO4, LiBF4, LiCF3SO3, LiAsF6, LiAlCl4, CF3SO3Li, (SO2F)2NLi (Chen: see [0057]).
Regarding claim 7, the combination of Chen, Jung, Park, and Pan teaches wherein a concentration of lithium salt is 0.2 to 2.0 M (Chen: see [0058]).
Regarding claim 11, the combination of Chen, Jung, Park, and Pan teaches the electrolyte solution further comprising at least one selected from the group consisting of lanthanum nitrate, potassium nitrate (Park: see [0057]), cesium nitrate (Park: see [0057]), magnesium nitrate, barium nitrate (Park: see [0057]), lithium nitrite (Park: see [0057]), potassium nitrite (Park: see [0057]), and cesium nitrite (Park: see [0057]).
Regarding claim 12, the combination of Chen, Jung, Park, and Pan teaches the battery, comprising:
2-methylfuran as the first solvent (Jung: lithium protection solvent, see [0029]),
1,2-dimethoxyethane as the second solvent (Jung: weak polar solvent, see [0027]; also see evidence by NIH in section 2.4.2 which cites “1,2-dimethoxyethane as a synonym for “dimethoxyethane”),
LiFSI ((SO2F)2NLi) as the lithium salt (Chen: see [0057]),
lithium difluoro(oxlato)borate (LiFOB) as the borate-based lithium salt (Chen: see [0057]; Pan: see [0014]), and
the lithium nitrate (Chen: see [0057]; Pan: see [0017]).
Regarding claim 13, the combination of Chen, Jung, Park, and Pan teaches a lithium-sulfur battery comprising, a positive electrode (Chen: cathode 24, see [0049]); a negative electrode (Chen: anode 22, see [0049]); a separator between the positive electrode and the negative electrode (Chen: separator 26 disposed between the electrodes 22, 24; [0050]); and the electrolyte solution according to claim 1 (see rejection for claim 1 above).
Claim(s) 3 is rejected under 35 U.S.C. 103 as being unpatentable over the combination of Chen, Jung, Park, and Pan as applied to claim 1 above, and further in view of Kim et al. (WO 2020/009340 A1, hereinafter “Kim”; using US PGPub 2021/0265662 for the English translation and citations; listed in the IDS filed 16 December 2022).
Regarding claim 3, the combination of Chen, Jung, Park, and Pan is silent to wherein the content of the borate-based lithium salt is 0.01 wt. % to 5.0 wt. % relative to the total weight of the electrolyte solution for the lithium-sulfur battery.
Kim teaches a borate-based lithium salt may be included in an amount of 0.1 wt% to 10 wt% based on a total amount of the electrolyte (see [0046]). Kim teaches that when borate-based lithium salt is used in an amount of less than 0.05wt%, the effect of suppressing the interface resistance may be insignificant, but when the boroate-based lithium salt is used in an amount greater than 20 wt%, viscosity and interface resistance may be increased, and accordingly, there may be a problem of not securing capacity and battery performance such as a cycle-life and the like (see [0048]). Therefore, the amount of borate-based lithium salt relative to the total weight of the electrolyte is a result effective variable.
In view of Kim’s teachings, it would have been obvious to one of ordinary skill in the art at the time the invention was filed to modify the invention of the combination of Chen, Jung, Park, and Pan to include wherein the content of the borate-based lithium salt is 0.01 wt. % to 5.0 wt. % relative to the total weight of the electrolyte solution for the lithium-sulfur battery, because it is a result effective variable (Kim: see [0048]), and it would not be inventive to discover its optimum range through routine experimentation. See MPEP §2144.05(II)(A).
Response to Arguments
Applicant's arguments filed 9 July 2026 have been fully considered but they are not persuasive.
On pages 4-8 of the remarks, Applicant argues that the prior art, either taken alone or in combination, fails to teach all the limitations of amended claim 1. More specifically, Applicant argues that the new limitation of wherein a weight ratio of the borate-based lithium salt to the lithium nitrate is 1:3 to 1:30 is not taught or suggested by the prior art. Additionally, Applicant argues that the volume ratio of the first solvent to the second solvent of 1:2.5 to 1.6 cannot be addressed with Park’s broad disclosure because Park’s broad disclosure cannot reasonably direct one of ordinary skill in the art to the more narrow claimed range.
The Examiner finds these arguments moot as amended claim 1 is now being rejected by the combination of Chen, Jung, Park, and Pan. Pan teaches a lithium metal battery electrolyte for a lithium-sulfur battery. Pan teaches that the electrolyte contains a solvent and three salts, wherein lithium salt II is lithium nitrate (LiNO3) (see [0017]) because it suppresses the continuous occurrence of side reactions thereby improving the cycle stability of lithium-sulfur batteries (see [0067]), and lithium salt III is a boron-containing lithium salt which can include lithium tetrafluoroborate (see [0014]) because it can further improve the electrochemical performance of lithium-sulfur batteries (see [0068]). Pan teaches that their mass percentages are lithium salt II 0.1% - 3% and lithium salt III 0.1% - 10% (see [0023]). Pan teaches that lithium-sulfur batteries assembled using their electrolyte improves cycle performance of the battery (see [0008] and [0064]).
In view of Pan’s teachings, it would have been obvious to one of ordinary skill in the art at the time the invention was filed to modify the electrolyte solution of the combination of Chen, Jung, and Park to include wherein a weight ratio of the borate-based lithium salt and to the lithium nitrate is 1:3 to 1:30, because it can help to improve cycle performance of the battery. In the case where the claimed ranges "overlap or lie inside ranges disclosed by the prior art" a prima facie case of obviousness exists. See MPEP §2144.05(I). Furthermore, the Applicant is reminded that where the general conditions of a claim are disclosed in the prior art, it is not inventive to discover the optimum or workable ranges by routine experimentation. See MPEP 2144.05(II)(A). Regarding the Applicant’s argument to Park and the claimed volume ratio, Applicant is reminded that where the claimed ranges "overlap or lie inside ranges disclosed by the prior art" a prima facie case of obviousness exists. See MPEP §2144.05(I). Furthermore, Applicant appears to be arguing unexpected results in the discussion regarding the poor performance of a 1:2 ratio in Comparative Example 2 which is outside Applicant’s claimed range. A singular point outside of the claimed range does not equate to a showing of unexpected results. Applicant is reminded that to establish unexpected results over a claimed range, applicants should compare a sufficient number of tests both inside and outside the claimed range to show the criticality of the claimed range. In re Hill, 284 F.2d 955, 128 USPQ 197 (CCPA 1960).
Conclusion
Applicant's amendment necessitated the new ground(s) of rejection presented in this Office action. Accordingly, THIS ACTION IS MADE FINAL. See MPEP § 706.07(a). Applicant is reminded of the extension of time policy as set forth in 37 CFR 1.136(a).
A shortened statutory period for reply to this final action is set to expire THREE MONTHS from the mailing date of this action. In the event a first reply is filed within TWO MONTHS of the mailing date of this final action and the advisory action is not mailed until after the end of the THREE-MONTH shortened statutory period, then the shortened statutory period will expire on the date the advisory action is mailed, and any nonprovisional extension fee (37 CFR 1.17(a)) pursuant to 37 CFR 1.136(a) will be calculated from the mailing date of the advisory action. In no event, however, will the statutory period for reply expire later than SIX MONTHS from the mailing date of this final action.
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/S.S.H/Examiner, Art Unit 1735 13 October 2026
/KEITH WALKER/Supervisory Patent Examiner, Art Unit 1735
