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 .
Response to Amendment
Applicant's arguments filed August 4, 2026, have been fully considered but they are not persuasive. Based on applicant’s amendments the rejection below has been updated to address the amendments.
Applicant first argues that amended claim 1 requires an El/S weight ratio of 2.5 g/g or lower and that Lee discloses a range of 2.9-3.2 g/g. Applicant therefore contends that there is no overlapping range.
Applicant's observation that Lee's expressly preferred range does not overlap the newly claimed upper limit is acknowledged. The rejection, however, is not maintained on the basis that Lee's disclosed 2.9-3.2 range overlaps the claimed range. Rather, Lee is relied upon for establishing that electrolyte quantity relative to the sulfur-containing positive electrode is a recognized battery-design parameter and for expressly teaching the effect of reducing that parameter below approximately 2.9. The claimed numerical value represents selection of a value of that known result-effective parameter according to the desired balance of battery characteristics.
Applicant next argues that Lee “explicitly teaches away” from the claimed El/S ratio because Lee states at paragraph [0047] that when the electrolyte-to-positive-electrode-active-material ratio is below 2.9, “the maximum capacity of the positive electrode active material cannot be expressed.”
The argument is not persuasive. Lee does not state that a battery having a ratio below 2.9 is inoperative, unsafe, incapable of discharge, or otherwise unsuitable for use as a lithium-sulfur battery. Rather, Lee identifies a consequence associated with lowering electrolyte quantity: maximum capacity of the positive-electrode active material is not expressed. Such disclosure informs the skilled artisan of a known performance tradeoff.
Claim 1 does not require maximum expression of the positive-electrode active-material capacity. Consequently, Lee's preference for ratios at or above approximately 2.9 in order to maximize that particular performance characteristic does not preclude a skilled artisan from selecting a lower ratio where another known design objective, such as reducing inactive electrolyte quantity and mass, is given greater weight.
The fact that a particular modification may reduce one known performance characteristic does not necessarily make the modification unobvious where the art recognizes competing considerations. A person of ordinary skill is presumed to possess ordinary creativity and to be capable of selecting among known alternatives according to the performance requirements of the particular application.
Here, Lee places the skilled artisan in possession of the relevant relationship: reducing electrolyte quantity below approximately 2.9 affects utilization of the positive-electrode active material. Thus, the result of moving below Lee's preferred range would have been predictable rather than unexpected.
Applicant has not identified evidence demonstrating that 2.5 g/g constitutes a critical boundary at which an unexpected property arises, as opposed to representing a further reduction of a known battery-design parameter. Nor does the claim recite a particular unexpected improvement attributable specifically to the 2.5 g/g upper limit.
Accordingly, the disclosure of Lee, considered together with Sumanasekera and the knowledge of one of ordinary skill in the lithium-sulfur battery art, would have rendered selection of the claimed El/S ratio obvious through routine balancing of known battery-performance considerations.
Applicant further argues that Yang cannot cure the alleged deficiencies of Sumanasekera with respect to claims 3, 6, and 9. The argument is not persuasive because the rejection has been clarified above to rely upon Sumanasekera in combination with Lee for the limitations of amended claim 1 and upon Yang for the additional limitations of claims 3, 6, and 9. Yang is not relied upon to independently disclose every limitation of claim 1.
Applicant similarly argues that Han cannot cure the alleged deficiencies of Sumanasekera with respect to claims 7 and 8. The argument is not persuasive for the same reason. Sumanasekera and Lee are relied upon for the limitations of amended claim 1, while Han is relied upon for the additional sulfur-carbon-composite content and sulfur-loading limitations of claims 7 and 8, respectively.
Applicant further argues that Sumanasekera, Han, and Lee fail to disclose every feature of claim 1 and therefore cannot render claim 13 obvious. The argument is not persuasive. The rejection does not require any individual reference to disclose every claimed limitation. Rather, the references are considered for what their combined teachings would have suggested to one of ordinary skill in the art. As discussed above, Sumanasekera provides the underlying lithium-sulfur battery, Lee establishes electrolyte quantity as a known performance-affecting parameter, and Han expressly teaches a sulfur loading of approximately 3.5 mAh/cm². When the claimed upper El/S value of 2.5 is applied to Han's sulfur loading, the resulting Sx is 1.4 mAh/cm², thereby satisfying claim 13.
Claim Rejections - 35 USC § 103
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.
Claims 1, 2, 4, 5, 11 and 12 are rejected under 35 U.S.C. 103 as being unpatentable over Sumanasekera (US 20200403224 A1), hereinafter Sumanasekera, in view of Lee (KR 20210088025 A), hereinafter Lee.
Regarding claim 1, Sumanasekera teaches a lithium sulfur battery (Abstract), comprising:
an electrode assembly ([0013], [0034], Fig. 1A-B), which comprises:
a positive electrode including a sulfur-carbon composite ([0013], [0034]);
a negative electrode ([0013], [0034]);
a separator between the positive electrode and the negative electrode ([0013], [0034]);
and an electrolyte ([0013], [0034]);
the lithium-sulfur battery at depth of discharge (DOD) 15% to DOD 80% comprises a compound having three or more characteristic peaks of diffraction angles (28 values) of X-ray diffraction (XRD) patterns selected from 7.1 ± 0.2°, 9.0 ± 0.2°, 9.4 ± 0.2°, 9.6± 0.2°, 9.9 ± 0.2°, 10.0 ± 0.2°, 10.4 ± 0.2°, 11.0 ± 0.2°, 11.6 ± 0.2°, 12.1 ± 0.2°, 13.3 ± 0.2°, 14.5 ± 0.2° and 15.0 ± 0.2° (Fig. 2, [0003]).
Sumanasekera further teaches operation of the lithium-sulfur battery through the claimed depth-of-discharge region, including DOD 15% to DOD 80% (Fig. 2; [0003]). Sumanasekera further discloses the electrochemical behavior and phase evolution of sulfur-containing electrode materials during discharge.
With respect to the claimed compound having three or more characteristic peaks at diffraction angles selected from 7.1 ± 0.2°, 9.0 ± 0.2°, 9.4 ± 0.2°, 9.6 ± 0.2°, 9.9 ± 0.2°, 10.0 ± 0.2°, 10.4 ± 0.2°, 11.0 ± 0.2°, 11.6 ± 0.2°, 12.1 ± 0.2°, 13.3 ± 0.2°, 14.5 ± 0.2°, and 15.0 ± 0.2°, such diffraction peaks characterize the composition and crystalline structure of the electrode materials existing during discharge. Where the same or substantially similar sulfur-containing electrode materials are subjected to the same or substantially similar electrochemical discharge conditions, the resulting crystalline phases would possess their characteristic X-ray diffraction peaks. Thus, the claimed diffraction peaks constitute properties resulting from the composition and state of the sulfur-containing electrode material during discharge.
Sumanasekera does not expressly teach that the weight ratio of electrolyte solution to sulfur in the sulfur-carbon composite (El/S weight ratio) is 2.5 g/g or lower.
Lee teaches a lithium-sulfur battery and expressly recognizes the amount of electrolyte relative to sulfur-containing positive-electrode material as a parameter affecting battery performance. In particular, Lee teaches an electrolyte-to-sulfur-related weight ratio and discloses values of approximately 2.9-3.2 g/g (Abstract; [0045]-[0047]). Lee therefore establishes that the relative amount of electrolyte and sulfur is a battery-design parameter known to affect electrochemical performance.
Lee further teaches at paragraph [0047] that when the weight ratio of the electrolyte to the positive electrode active material is below 2.9, “the maximum capacity of the positive electrode active material cannot be expressed,” and identifies preferred ranges of 2.95-3.2 and, more preferably, 2.95-3.15. Thus, Lee expressly demonstrates that lowering the relative electrolyte quantity below approximately 2.9 was contemplated and that the consequence of doing so was understood in the art. Lee's statement identifies a performance tradeoff associated with reducing electrolyte quantity rather than establishing that a lithium-sulfur battery could not be made or operated at a lower ratio.
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 lithium-sulfur battery of Sumanasekera by selecting and reducing the amount of electrolyte relative to sulfur, including to a value of 2.5 g/g or lower, because Lee establishes the electrolyte-to-sulfur-related ratio as a parameter affecting battery performance and expressly identifies the effect produced when that parameter is reduced below approximately 2.9.
A person of ordinary skill in the lithium-sulfur battery art would have recognized that electrolyte quantity involves known competing considerations. Increasing electrolyte quantity may facilitate sulfur utilization and capacity, whereas reducing electrolyte quantity reduces inactive electrolyte mass and volume and thereby can improve gravimetric and volumetric characteristics of the cell. Selection of the particular ratio therefore represents the balancing of known battery-design considerations according to the performance sought.
The fact that Lee indicates that maximum capacity of the positive electrode active material cannot be expressed below a ratio of 2.9 does not render the proposed modification nonobvious. The claimed battery does not require that the maximum theoretical or practically obtainable capacity of the positive electrode active material be expressed. Nor does claim 1 require optimization of capacity. Lee instead informs one of ordinary skill of the expected consequence of reducing electrolyte quantity. A known disadvantage or reduction in one performance characteristic does not, by itself, render a known design choice unobvious where the skilled artisan would have recognized competing advantages associated with the modification.
Accordingly, Lee's disclosure would not have led a person of ordinary skill to conclude that ratios below 2.9 were inoperative or technically infeasible. Rather, Lee teaches that such ratios result in a known capacity tradeoff. One of ordinary skill seeking to reduce the quantity and weight of electrolyte in Sumanasekera's lithium-sulfur battery would have had reason to accept that known tradeoff and employ a lower electrolyte-to-sulfur ratio.
Selection of 2.5 g/g or lower therefore would have amounted to selection of a value of a known result-effective battery-design variable through routine experimentation, with the expected tradeoff between electrolyte quantity and sulfur utilization/capacity. The particular upper limit of 2.5 g/g has not been shown to represent a critical value producing an unexpected result commensurate in scope with the claim.
Regarding claim 2, Sumanasekera teaches the limitations of claim 1 as set forth above. Sumanasekera further teaches that the lithium-sulfur battery through the relevant depth-of-discharge region operates within a potential range encompassing the claimed 1.7 to 2.2 V (Fig. 5A). To the extent optimization of the operating conditions is implicated, selecting an operating potential appropriate for a given DOD is a result-effective variable and would have been within the ordinary skill in the art to achieve predictable battery performance.
Regarding claim 4, Sumanasekera teaches the limitations of claim 1 as set forth above. Sumanasekera further teaches the lithium-sulfur battery through the relevant DOD region (Fig. 2; [0003]). As discussed above, the diffraction peaks obtained via X-ray diffraction characterize the composition and crystalline structure of the sulfur-containing electrode materials. The same or substantially similar materials undergoing the same electrochemical reactions would exhibit their corresponding characteristic diffraction peaks.
Regarding claim 5, Sumanasekera teaches the limitations of claim 1 as set forth above. Sumanasekera further teaches the lithium-sulfur battery through the relevant DOD region (Fig. 2; [0003]). For the reasons discussed above regarding claim 4, the characteristic X-ray diffraction peaks are properties of the crystalline phases produced by the disclosed sulfur-containing electrode material during discharge.
Regarding claim 11, Sumanasekera teaches the limitations of claim 1 as set forth above. Sumanasekera further teaches a lithium-sulfur battery having an energy density of at least 300 Wh/kg ([0010], [0026]). Energy density is a result-effective battery-performance variable. It would have been obvious to optimize the known battery construction, including the relative quantities of active and inactive materials, to increase energy density, including to 430 Wh/kg or greater, because increasing gravimetric energy density is a recognized design objective for lithium-sulfur batteries.
Regarding claim 12, Sumanasekera teaches the limitations of claim 1 as set forth above. Sumanasekera further teaches that the lithium-sulfur battery may be provided in a cylindrical battery configuration ([0010], [0041]).
Claims 3, 6 and 9 are rejected under 35 U.S.C. 103 as being unpatentable over Sumanasekera (US 20200403224 A1), hereinafter Sumanasekera, as applied to claim 1 above, in further view of Yang et al. (US 20220388850 A1), hereinafter Yang.
Regarding claim 3, Sumanasekera and Lee teach or suggest the limitations of claim 1 as stated above. Sumanasekera further teaches operation over DOD 15% to DOD 80% and a discharge capacity per sulfur weight overlapping the claimed range of 150-960 mAh/g(S) (Fig. 9B).
Additionally, Yang teaches a lithium-sulfur battery having a discharge capacity of approximately 800-1050 mAh/g. Yang and Sumanasekera are analogous art because both concern lithium-sulfur batteries and optimization of their electrochemical performance. The claimed range of 150-960 mAh/g overlaps the capacity ranges disclosed by Sumanasekera and Yang.
It would therefore have been obvious to one of ordinary skill in the art to operate the modified Sumanasekera battery to obtain a discharge capacity within the claimed range because discharge capacity is a result-effective battery-performance variable and the prior-art ranges overlap the claimed range.
Regarding claim 6, Sumanasekera and Lee teach or suggest the limitations of claim 1 as stated above. Sumanasekera fails to expressly teach that the sulfur-carbon composite has a sulfur/carbon (S/C) weight ratio of 2.3 g/g or more.
Yang teaches a sulfur-carbon composite having sulfur/carbon weight ratios including ratios from approximately 1:1 to 1:9 (Claim 11; [0084], [0060]). The disclosed ratios encompass sulfur-rich compositions corresponding to an S/C weight ratio of at least 2.3 g/g.
Sumanasekera and Yang are analogous art because both concern lithium-sulfur batteries. It would have been obvious to select the relative sulfur and carbon amounts within the known ranges according to the desired balance between sulfur active-material loading and conductive carbon because sulfur/carbon ratio is a known result-effective variable affecting battery capacity and conductivity.
Regarding claim 9, Sumanasekera and Lee teach or suggest the limitations of claim 1 as stated above. Sumanasekera does not expressly teach a negative electrode having a thickness of 40 to 80 μm.
Yang teaches a negative-electrode thickness within a broad range of approximately 3 to 500 μm ([0111]), which encompasses the claimed range of 40 to 80 μm.
It would have been obvious to one of ordinary skill in the art to select a negative-electrode thickness within the claimed range because electrode thickness is a known result-effective variable affecting capacity, energy density, resistance, and transport characteristics, and the claimed range lies entirely within the range expressly disclosed by Yang.
Claims 7-8 are rejected under 35 U.S.C. 103 as being unpatentable over Sumanasekera, as applied to claim 1 above, in further view of Han et al. (US 20210288327 A1), hereinafter Han.
Regarding claim 7, Sumanasekera and Lee teach or suggest the limitations of claim 1 as stated above. Sumanasekera does not expressly teach that the weight of the sulfur-carbon composite is 90 wt% or more based on the total weight of the positive electrode.
Han teaches a sulfur-carbon-composite content of approximately 80 wt% based on the total weight of the positive electrode ([0136]).
Sumanasekera and Han are analogous art because both concern lithium-sulfur batteries and positive electrodes containing sulfur-carbon active material. It would have been obvious to one of ordinary skill in the art to increase the amount of sulfur-carbon composite in the positive electrode from Han's 80 wt% toward and including 90 wt% or greater because the proportion of active material is a result-effective variable affecting battery capacity and energy density. Optimization of the relative quantities of active material, binder, and conductive material would have involved routine experimentation according to the desired electrode performance.
Regarding claim 8, Sumanasekera and Lee teach or suggest the limitations of claim 1 as stated above. Sumanasekera does not expressly teach a positive electrode having a sulfur loading amount of 2 to 5 mAh/cm².
Han teaches a positive electrode having a sulfur loading amount of approximately 3.5 mAh/cm² ([0122]), which falls squarely within the claimed range of 2 to 5 mAh/cm².
Therefore, it would have been obvious to one of ordinary skill in the art to employ Han's expressly disclosed sulfur loading in the lithium-sulfur battery of Sumanasekera as modified by Lee because Han concerns the same type of lithium-sulfur battery electrode and expressly provides a sulfur loading within the claimed range.
Claim 13 is rejected under 35 U.S.C. 103 as being unpatentable over Sumanasekera, in view of Han, and in further view of Lee.
Regarding claim 13, Sumanasekera and Lee teach or suggest the limitations of claim 1 as set forth above. Claim 13 further requires:
Equation I:
[Equation l]
SX = SPE / SEL/S
SPE is a sulfur (S) loading amount of the positive electrode having a unit of mAh/cm2;
SEL/S is a weight ratio of the electrolyte to sulfur (S);
SX is the sulfur (S) loading amount of the positive electrode per the weight ratio of the electrolyte to the sulfur (S), and SX is 1.4 mAh/cm2 or higher
As stated above with respect to claim 8, Han teaches a positive electrode having a sulfur loading amount (S_PE) of approximately 3.5 mAh/cm² ([0122]).
As stated above with respect to claim 1, Lee teaches the electrolyte-to-sulfur-related ratio as a parameter affecting lithium-sulfur battery performance (Abstract; [0045]-[0047]) and expressly identifies the performance consequence associated with reducing electrolyte quantity below approximately 2.9. For the reasons discussed with respect to claim 1, it would have been obvious to optimize that parameter, including by reducing the electrolyte quantity to an El/S ratio of 2.5 g/g or lower where reduced electrolyte mass and increased gravimetric characteristics were desired.
Applying Han's disclosed sulfur loading of approximately 3.5 mAh/cm² and an El/S ratio of 2.5 g/g yields:
SX = 3.5 / 2.5 = 1.4 mAh/cm².
Thus, the combination expressly satisfies the lower boundary required by claim 13. Further reduction of the El/S ratio below 2.5 while maintaining Han's sulfur loading would produce an SX value greater than 1.4 mAh/cm².
Sumanasekera, Han, and Lee are analogous art directed to lithium-sulfur batteries. It would have been obvious to one of ordinary skill in the art to balance sulfur loading and electrolyte quantity because both are known result-effective variables affecting energy density, ion transport, capacity, sulfur utilization, and cycling characteristics. The claimed SX value follows directly from selection of the known sulfur loading and electrolyte-to-sulfur parameters.
Conclusion
Applicant's amendment necessitated the new ground(s) of rejection presented in this Office action. Accordingly, THIS ACTION IS MADE FINAL. 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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/TAMARA ORDUNA/Examiner, Art Unit 1776
/Jennifer Dieterle/Supervisory Patent Examiner, Art Unit 1776
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