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 .
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.
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.
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 1-2, 6, 7 and 8 are rejected under 35 U.S.C. 103 as being unpatentable over Hashimoto (US 8,623,551) in view of Zhang (US 2003/0175588).
With regard to claims 1, 7 and 8, Hahsimoto teaches a non-aqueous electrolyte secondary battery having a positive electrode compromising a positive electrode mixture including at least a positive electrode active material, a conductive agent, and a binder (claim 1; throughout). The specific surface area of the positive electrode mixture is taught to be 0.9-1.5 m2/g (claims). The specific surface area of the positive electrode active material is taught to be 0.2-0.4 m2/g (claims). The active material is bonded to an electrode core current collector (examples).
Hahsimoto does not specifically teach a ratio (Spo/Sm) of a BET specific surface area of the positive electrode mixture (Spo) to a BET specific surface area of inorganic particles including the positive electrode active material and the conductive agent (Sm) is 1.0 to 2.0. This ratio compares the positive active mixture, including at least a positive electrode active material, a conductive agent and a binder, to a mixture that includes positive electrode active material and the conductive agent. From this, the binder is not included in the denominator of the ratio. The Hahsimoto reference teaches that the specific surface area of the conductive material and the binder is selected to be greater than that of the active material (“Examples of conductive assistants composed of carbon materials that can be used for the positive electrode include graphites such as natural graphite (flaky graphite, etc.) and artificial graphite; acetylene black, ketjen black, channel black, furnace black, lamp black, thermal Carbon blacks such as black; carbon fibers; In the positive electrode of the present invention, among these carbon materials, those having the above specific surface area are preferable.”). Since the specific surface area of the positive electrode mixture is taught to be 0.9-1.5 m2/g, one of ordinary skill in the art would recognize that the specific surface area of conductive material and binder would complement the active material in order to have a specific surface area 0.9-1.5 m2/g. It would have been obvious to one of ordinary skill in the art at the time of the invention to have a conductive material and the binder with a specific surface area that is in the range of the other materials in order to conduct electrons and bind the materials without increasing the total specific surface area beyond what is taught. Having materials in this range would yield a ratio of greater than about 1.
Hahsimoto does not specifically teach that the binder is a fibrous binder. Zhang (US 2003/0175588) teaches a battery having a positive electrode compromising a positive electrode mixture including at least a positive electrode active material, a conductive agent, and a fibrous binder (claim 1; claim 3, [0022], throughout). It would have been obvious to one of ordinary skill in the art to have used a fibrous binder in the positive electrode of Hahsimoto to bind the active material and conductive agent. Binder materials of Zhang are included in the list of possible binders taught and used in Hahsimoto.
With regard to claim 2, Hahsimoto does not explicitly teach that the void ratio of the positive electrode mixture is 35% or less. Hahsimoto teaches that the density of a positive mix layer is 3.6-4.3 g/cm3. It would have been obvious to one of ordinary skill in the art to have a positive electrode mixture void ratio of 35% or less because one of ordinary skill in the art would desire to increase the electrode/battery capacity while allowing for optimal electrical conduction through the electrode by the conductive material.
With regard to claim 6, Hahsimoto teaches a soluble binders used to form positive electrode mixture, The amount of binder in the mixture is preferably 0.4 parts by mass or less, with respect to 100 parts by mass of the positive electrode active material. In example 1, the positive electrode active material is mixed with acetylene black BET specific surface area: 65 m2/g, a rubber binder, and mixed at a solid mass ratio of 100: 1.2: 0.2: 0.8. The amount of soluble binder in the mixture is less than 1 mass percent.
Claims 3-5 are rejected under 35 U.S.C. 103 as being unpatentable over Hashimoto (US 8,623,551) in view of Zhang (US 2003/0175588), as applied above, and further in view of Tabushi et al. (US 2020/0194781).
The teachings of Hashimoto (US 8,623,551) in view of Zhang (US 2003/0175588) have been presented. The combination of references does not teach a positive electrode mixture bisected into two layers in a thickness direction having the (Spo) being 4.5 m2/g or less in both of the layers.
Tabushi et al. teaches a lithium secondary battery positive electrode mixture bisected into two lavers in a thickness direction having the (Spo) being 4.5 m2/g or less in both of the layers. The first layer has a BET specific surface area of 1.6-2.8 m2/g (claims). The second layer has a BET specific surface area of 0.8-1.3 m2/g (claims). The amount of binder used in Example 1 is about 3%. It would have been obvious to one of ordinary skill in the art to include two layers in a positive electrode to increase output by having a high BET specific surface area on the positive electrode core side. Further, the entrance of air moisture can be inhibited by disposing a second layer having a low BET specific surface area.
Conclusion
The prior art made of record and not relied upon is considered pertinent to applicant's disclosure. Yamamoto (JP-4059556) teaches fibrous binders in lithium batteries.
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/MARK RUTHKOSKY/Primary Patent Examiner, Art Unit 1785