DETAILED ACTION
Notice to Applicant
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and the fee set forth in 37 CFR 1.17(e) has been timely paid, the finality of the previous Office action has been withdrawn pursuant to 37 CFR 1.114.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 2026-02-12 has been entered.
In the amendment dated 2023-02-12, the following has occurred: Claim 1 has been amended; Claims 4-6 have been (previously) canceled.
Claims 1-3 and 7-13 are pending and are examined herein. This is a Non-Final Rejection.
The text of those sections of Title 35, U.S. Code not included in this action can be found in a prior Office action.
Claim Rejections - 35 USC § 103
Claims 1-3 and 7 are rejected under 35 U.S.C. 103 as being unpatentable over Wang (US Patent No. 8,871,387 to Wang et al.), in view of Zhou (Zhou et al. “A carbon cloth-based lithium composite anode for high-performance lithium metal batteries.” Energy Storage Materials 14 (2018) 222-229) and Shang (Shang et al. “Scalable Synthesis of LiF-rich 3D Architected Li Metal Anode via Direct Lithium-Fluoropolymer Pyrolysis to Enable Fast Li Cycling.” Energy Environ. Mater. 2021, 4, 213-221).
Regarding Claims 1-3, Wang teaches:
an electrode for an electrochemical cell (abstract, column 1), wherein the electrode can be an anode, for use in a lithium-sulfur cell (column 4 lines 58-62)
wherein the anode conductive support can be selected from a woven carbon mesh, non-woven carbon mesh, and carbon felt (column 15 lines 13-15)
wherein the conductive support is coated in a polymer layer that forms crosslinks, including fluoropolymers, such as PVDF and PTFE (column 12)
and then coated with an active material such as lithium (which is “applied” thereto) (column 17 line 15)
Wang teaches a long list of polymer primers, and does not teach a specific example with a porous carbon support, coated in a fluoropolymer, to which electroactive lithium metal is then applied. Zhou, however, from the same field of invention, regarding an anode for a lithium battery, teaches a carbon cloth-based lithium composite anode, wherein a lithium metal foil is applied to a supporting carbon cloth to coat the outer surface and inner pores of the cloth (Fig. 1). Furthermore, Shang, also from the same field of invention, teaches the benefits of providing a PTFE 3d network for hosting lithium which can react to form LiF that guides the redeposition of lithium during cycling (pp. 213, 220-221, etc.). It would have been obvious, therefore to provide a carbon mesh or cloth that is laminated with lithium foil, as suggested by Wang and Zhou, and to provide a primer polymer layer specifically comprising PTFE as suggested by Wang and Shang, with the motivation to provide a suitable carbon-based host material for lithium that also includes a primer fluoropolymer layer that forms a LiF upon contact with lithium to improve cycling and adhesion within the carbon host.
Wang further teaches:
carbon fiber mesh (column 15)
wherein the thickness of the primer layer ranges from 1-2 microns in the examples, and the thickness of the substrate ranges from about 6 to 12 microns in the examples
Shang teaches:
porous fibrous structure with a thickness of 15 microns (p. 214)
Assuming roughly equal densities for PTFE/PVDF of around 1.8 g/cm3 and a porous carbon substrate of a bit less, because of the porosity 0.75-1 g/cm3, Wang implies a primer weight to carbon cloth weight ratio of 1:3, and some of the primer would be expected to infiltrate the pores of the cloth/felt. Using conservative estimates, assuming a fluorine wt% of standard PVDF of around 60%, with standard PTFE being a bit higher at around 75%, and a thickness of 1/7 for the polymer primer layer and a thickness of 6/7 for the porous carbon cloth, we would expect a range of ~21-27 parts by weight fluorine per 100 parts carbon for PTFE and ~16-21 parts by weight fluorine per 100 parts carbon for PVDF. The parts fluorine would be slightly higher when accounting for some polymer that infiltrates pores near the surface. 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 [R-5]).
The claim limitation requiring “lithium metal applied on an outer surface and inside of the three-dimensional carbon structure” would seem to be met during the rolling/laminating process of applying the soft lithium metal foil to the coated carbon substrate, or, conversely, during cycling, where lithium would be expected to plate within pores of the carbon cloth.
The claim limitation “wherein the fluorine-based polymer is contained in an amount of 10% by weight or more and less than 20% by weight relative to the total weight of the aqueous solution” is interpreted as a product-by-process limitation. Product-by-process claims are not limited to the manipulations of the recited steps, only the structure implied by the steps. “[E]ven though product-by-process claims are limited by and defined by the process, determination of patentability is based on the product itself. The patentability of a product does not depend on its method of production. If the product in the product-by-process claim is the same as or obvious from a product of the prior art, the claim is unpatentable even though the prior product was made by a different process.” In re Thorpe, 777 F.2d 695, 698, 227 USPQ 964, 966 (Fed. Cir. 1985). See MPEP 2113 [R-1]. In the instant case, application via aqueous solutions of 6-8 wt% polymer are interpreted to produce substantially similar primer layers absent evidence that the claimed method step produces a materially different coating. The Office points out that the instant specification appears to indicate that aqueous polymer solutions of 2 wt% or more produce substantially similar layers as the claimed range (¶ 0040 of PGPUB US 2023/0253556).
Regarding Claim 7, Wang does not teach:
lamination of the lithium foil
Zhou, however, teaches lamination of the lithium foil directly on the porous carbon layer (Fig. 1, etc.). Lamination was a well-known lithium anode forming technique, as demonstrated by Zhou, that would have been obvious to one of ordinary skill in the art absent a showing of criticality in comparison to other application methods. Use of a known technique to improve similar devices, methods, or products in the same way, and applying a known technique to a known device, method, or product ready for improvement to yield predictable results has been found to be obvious. See KSR Int'l Co. v. Teleflex Inc., 550 U.S. 398 (2007).
Claims 1-3 and 7-13 are rejected under 35 U.S.C. 103 as being unpatentable over Zhou (Zhou et al. “A carbon cloth-based lithium composite anode for high-performance lithium metal batteries.” Energy Storage Materials 14 (2018) 222-229) in view of Wang2 (Wang et al. “Tuning wettability of molten lithium via a chemical strategy for lithium metal anodes.” Nature Communications (2019) 10:4930) and Shang (Shang et al. “Scalable Synthesis of LiF-rich 3D Architected Li Metal Anode via Direct Lithium-Fluoropolymer Pyrolysis to Enable Fast Li Cycling.” Energy Environ. Mater. 2021, 4, 213-221); with reference to the Toray™ specification of commercially available carbon cloth for evidence of ordinary skill and understanding in the art.
Regarding Claim 1, Zhou teaches:
a three-dimensional carbon structure of commercially available carbon cloth (p. 223, Fig. 1)
press-coated with lithium (Fig. 1), wherein some lithium would be expected to infiltrate the inner pores of the carbon cloth
Zhou does not teach:
a fluorine-based polymer coating, wherein the fluoropolymer coated carbon structure has 5-30 parts by weight of fluorine relative to 100 parts by weight of carbon
Wang2, however, from the same field of invention, regarding lithium anodes, teaches coating a lithium anode substrate with polymer, such abietic acid, or a fluoropolymer, such as PVDF (Fig. 2, p. 5, see also attached Supplementary Figs. 12-13) to improve the wettability of lithium metal on the substrate. Wang2 also teaches polymer concentrations of 10-40 wt%. Likewise, Shang, also from the same field of invention, teaches the benefits of providing a PTFE 3d network for hosting lithium which can react to form LiF that guides the redeposition of lithium during cycling (pp. 213, 220-221, etc.).
Furthermore, Wang2 teaches that more resin content in the coating liquid improves infusion in to the pores of the carbon fiber felt, providing better performance (increasing concentration from 10 to 40 wt% polymer, p. 2, column 2), and that the thickness of the polymer coating layer was on the order of 500 nm after infiltration (Methods, p. 7). The Office points to the specification of commercially available Toray™ carbon cloth, with fibers having a diameter of 7 µm as representative in the field (see attached production specification). Assuming the fibers are entirely coated with a 500 nm thick fluoropolymer, the Vcoating/Vcarboncloth would be roughly 65% for cloth made of 7 µm fibers. With PVDF at ~60 wt% fluorine, and a density roughly equal to carbon cloth, that would put the total fluorine at around 30 parts per 100 parts by weight of carbon:
0.65 coating mass · 60 wt% fluorine / [[40 wt% carbon · 0.65 coating mass] + 1 carbon fiber mass] = ~ 30 parts fluorine per 100 parts carbon
Assuming partial coverage, would drop the parts fluorine. But given that Wang2 teaches that more coating of the fibers is better, one of ordinary skill in the art would shoot for the upper end of that range, which is around the end range claimed. It therefore would have been obvious to provide a coating of at least 19 parts and at most 30 parts fluorine per 100 parts carbon for a PVDF-coated carbon cloth for use as a lithium anode, as taught by Zhou in view of Wang2. 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 [R-5]).
The claim limitation requiring “lithium metal applied on an outer surface and inside of the three-dimensional carbon structure” is interpreted to be met because Wang2 refers to the “infusion” of lithium metal into the substrate (p. 2 column 2).
The claim limitation “wherein the fluorine-based polymer is contained in an amount of 10% by weight or more and less than 20% by weight relative to the total weight of the aqueous solution” is interpreted as a product-by-process limitation. Product-by-process claims are not limited to the manipulations of the recited steps, only the structure implied by the steps. “[E]ven though product-by-process claims are limited by and defined by the process, determination of patentability is based on the product itself. The patentability of a product does not depend on its method of production. If the product in the product-by-process claim is the same as or obvious from a product of the prior art, the claim is unpatentable even though the prior product was made by a different process.” In re Thorpe, 777 F.2d 695, 698, 227 USPQ 964, 966 (Fed. Cir. 1985). See MPEP 2113 [R-1]. In the instant case, application via aqueous solutions of 6-8 wt% polymer are interpreted to produce substantially similar primer layers absent evidence that the claimed method step produces a materially different coating. The Office points out that the instant specification appears to indicate that aqueous polymer solutions of 2 wt% or more produce substantially similar layers as the claimed range (¶ 0040 of PGPUB US 2023/0253556).
Regarding Claim 2, Zhou teaches:
porous carbon cloth (abstract)
Regarding Claim 3, Zhou teaches:
commercially available carbon cloth/paper/felt/mat (p.2)
Regarding Claim 7, Zhou teaches:
laminating the lithium foil to the carbon cloth (Fig. 1)
Regarding Claims 8 and 9, Wang2 and Shang render obvious:
use of fluoropolymers in the anode, which is known to react to form LiF (see e.g. discussion in Wang2 and Shang regarding “LiF” formation)
Given that it would have been obvious to provide coatings of PVDF and/or PTFE on the carbon cloth of Zhou to improve wettability of the lithium, as taught in Wang2, such a coating would be expected to form LiF upon lithium application/plating, and such formation would be expected to form at an “interface” as claimed, since the polymer was coated on the carbon cloth.
Regarding Claim 10, Wang2 and Shang render obvious:
conventional fluoropolymers like PVDF and PTFE
Regarding Claims 11-13, Zhou teaches:
cathode, anode, and separator, with electrolyte (p. 225)
Zhou does not explicitly teach:
a lithium-sulfur battery
Lithium sulfur batteries were known in the art, however, and it would have been obvious to use the anode rendered obvious by Zhou/Wang2/Shang with other cathodes known in the art, including lithium transition metal oxides, and sulfur-based cathodes. Simple substitution of one known element for another to obtain predictable results has been found to be obvious. See KSR Int'l Co. v. Teleflex Inc., 550 U.S. 398 (2007).
Response to Arguments
The Remarks filed 2026-02-12 have been considered but are not persuasive. Applicant argues that the prior art does not teach the claimed wt% polymer aqueous solution used to coat the carbon structure. This, however, is interpreted as a product-by-process limitation not directly tied to the positive structural features of the resulting coated carbon structure. The instant specification indicates substantially similar coatings can be formed from solutions with polymer wt% as low as 2%. Absent evidence that the claimed 10-20 wt% produces materially different products from what the prior art teaches (e.g. 6-8 wt% for Wang, and 10-40 wt% for Wang2), the claim limitation does not appear to differentiate the claimed negative electrode from what is taught or rendered obvious by the prior art.
Applicant argues that the prior art does not teach that the lithium metal “covers the surface thereof and fills inside thereof.” Respectfully, the claim does not require “filling” the inside of the carbon structure: “lithium metal applied on an outer surface and inside of the three-dimensional carbon structure coated with the fluorine-based polymer.” All of the prior art cited teaches at least some form of pressing lithium metal into a porous carbon structure, which would be expected to result in some soft lithium metal entering the pores of the material, even if only at the surface. Other references teach more explicit “infusions,” like Liu and Wang2. The prior art is therefore interpreted to teach “inside of” within the broadest reasonable interpretation of that phrase.
Arguments about Wang2 “merely disclos[ing] an abietic resin solution” are incorrect. Wang2 teaches abietic resin as well as PVDF (Remarks at p. no. 10; see Supplementary Fig. 13 of Wang2 and p. 5 of the main article). Conservative estimations of the amount of fluorine by weight per 100 wt carbon for both Wang and Wang2 appear to significantly overlap the claimed range.
Conclusion
Any inquiry concerning this communication or earlier communications from the examiner should be directed to Michael Dignan, whose telephone number is (571) 272-6425. The examiner can normally be reached from Monday to Friday between 10 AM and 6:30 PM. If any attempt to reach the examiner by telephone is unsuccessful, the examiner’s supervisor, Tiffany Legette, can be reached at (571)270-7078. Another resource that is available to applicants is the Patent Application Information Retrieval (PAIR). Information regarding the status of an application can be obtained from the (PAIR) system. Status information for published applications may be obtained from either Private PAIR or Public PAX. Status information for unpublished applications is available through Private PAIR only. For more information about the PAIR system, see http://pair-direct.uspto.gov. Should you have questions on access to the Private PAIR system, please feel free to contact the Electronic Business Center (EBC) at 866-217-9197 (toll-free). Applicants are invited to contact the Office to schedule an in-person interview to discuss and resolve the issues set forth in this Office Action. Although an interview is not required, the Office believes that an interview can be of use to resolve any issues related to a patent application in an efficient and prompt manner.
/MICHAEL L DIGNAN/Examiner, Art Unit 1723