DETAILED ACTION
Continued Examination Under 37 CFR 1.114
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and the fee set forth in 37 CFR 1.17(e) has been timely paid, the finality of the previous Office action has been withdrawn pursuant to 37 CFR 1.114.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 Dec. 26, 2025 has been entered.
Status of Claims
Claim 1 has been amended. Claims 1-3 and 5-7 are pending and being examined on the merits in this office action.
Remarks
Applicant’s amendments and arguments have been entered. A reply to the Applicant’s remarks/arguments is presented after addressing the claims.
Any rejections and/or objections made in the previous Office Action and not repeated below, are hereby withdrawn in view of Applicant’s amendments or/and arguments.
The text of those sections of Title 35, U.S. Code not included in this action can be found in a prior Office action. References cited in the current Office action can be found in a prior Office action. Reference not previously cited can be found per the attached PTO-892 for this Office action.
Claim Rejections - 35 USC § 103
Claims 1-3 and 5-7 are rejected under 35 U.S.C. 103 as being unpatentable over Cho et al. (US 20190036121 A1, hereafter Cho) in view of Park et al. (US 20210210751 A1, hereafter Park), Wilson et al. (US 5624606, hereafter Wilson) and Cho et al. (WO 2020138629 A1, whose English machine translation is being employed for citation purposes, hereafter Cho-II).
Regarding claims 1-2, Cho teaches a method (See at least [0072] and [0118]) of preparing a negative electrode active material for a lithium secondary battery, the method comprising:
(a) a step of mixing, stirring, and then firing a first carbon precursor (“pitch”, [0118]) and a ceramic particle (“powder-type SiO2”, [0118]) for forming pores with each other ([0118]);
(b) a step of preparing a carbon-based particle including pores in an inner portion and/or a surface thereof by mixing an etching solution (“NaOH solution”, [0118]) with the ceramic particle for forming pores (“porous carbon structure”, [0118]) and pulverizing (Note that the pulverizing is a routine process for one of ordinary skill in the art); and
(c) a step of forming a silicon-based coating layer containing silicon carbon compound on a pore surface and/or a pore-free surface of the carbon-based particle by chemical vapor deposition (CVD) of, e.g., SiH4 ([0121], Cho: “chemical deposition of SiH4(g)”) which releases Si atoms by gasification ([0084], Cho). Note that it is known in the art that Si will react with carbon to form SiC, as exemplified by Park (See [0033]).
Although a carbon precursor gas is not involved in the formation of SiC, the use of carbon precursor in a form of gas phase is well known in the art. For instance, Wilson discloses that a silicon carbon compound can be formed by a CVD technique, wherein a silicon precursor gas and a carbon precursor gas are simultaneously injected into a reactor and reacted with each other (See, at least: Fig. 3; the paragraph bridging columns 7 and 8; paragraphs 2-4 of column 7). The resultant silicon carbon compound, such as silicon-carbide, has large reversible capacity for lithium and are suitable for use as high-capacity anode in lithium-ion batteries (Abstract). Thus, it would have been obvious to one of ordinary skill in the art before the effective filing date of the instant invention to have employed the CVD technique disclosed by Wilson as an alternative of Cho’s CVD technique for the benefits stated above. Note that Wilson discloses the CVD is performed in an ultra-high purity argon environment (bottom of column 7), which reads on an inert atmosphere as claimed. Furthermore, Wilson explicitly teaches that “the relative ratios of the carbon and silicon sources can be adjusted by controlling the flow rates of argon through each source bottle” (column 8, lines 1-4). As such, one of ordinary skill in the art would readily arrive at various injection rate of the silicon precursor gas and the carbon precursor gas through routine experimentation, including those ratios as claimed in claim 1.
As to the limitation “the silicon-based coating layer includes a silicon carbon compound matrix and Si nano-particles dispersed in the matrix”, since “the relative ratios of the carbon and silicon sources can be adjusted by controlling the flow rates of argon through each source bottle” (column 8, lines 1-4, Wilson), one of ordinary skill in the art would readily adjust the said relative ratios to be any desired values through routine experimentations, including a ratio with excess silicon (compared with carbon) which would result in the silicon-based coating layer comprising the SiC matrix in which Si nanoparticles formed from excess silicon are dispersed. MPEP § 2144.05.
Cho as modified appears silent on the Si nano-particles having an average particle diameter of 3 nm to 10 nm.
Cho-II discloses that a size of silicon particles produced by CVD method can be controlled by adjusting amounts of CVD precursors of silane-based gas and hydrocarbon gas (at least: [0063]). When the silicon particles have a particle size of 3 nm to 5 nm can improve life characteristics and avoid deteriorating battery performance (at least: [0044]-[0046]).
It would have been obvious to one of ordinary skill in the art, before the effective filing date of the instant invention, to have further modified Cho such that a particle size of silicon particles in Cho in view of Park and Wilson is controlled to be 3 nm to 5 nm, as taught by Cho-II, in order to achieve advantages such as improving life characteristics and avoiding deteriorating battery performance (at least: [0044]-[0046], Cho-II). The claimed range of 3 nm to 10 nm overlaps that of 3 nm to 5 nm. 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).
Regarding claim 3, Cho as modified teaches the method of claim 1, further comprising, after the step (c), a step of mixing, stirring, and then firing a second carbon precursor with the carbon-based particle (See “pitch”, [0130], Cho).
Regarding claim 5, Cho as modified teaches the method of claim 1, wherein the ceramic particle for forming pores has an average particle diameter of 200 nm ([0118], Cho), reading the range as instantly claimed.
Regarding claim 6, Cho as modified teaches the method of claim 1, wherein in the step (c), the silicon-based coating layer is deposited at a thickness of 5 nm to 100 nm ([0060], Cho), reading on the instantly claimed range.
Regarding claim 7, Cho as modified teaches the method of claim 3, wherein a firing temperature in the step (a) and/or the step (d) is 800 [Symbol font/0xB0]C or more ([0082], Cho), overlapping the instantly claimed range of temperature. 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).
Response to Arguments
Applicant's arguments filed on Dec. 26, 2025 have been fully considered but they are not persuasive.
1) Applicant mainly argues that “The Examiner’s allegation of routine experimentation is without basis in law … Thus, routine optimization is not a proper rationale to arrive at the present invention, because the prior art does not recognize the carbon: silicon ratio as a result-effective variable”.
In response, first of all, it is noted that “… after KSR, the presence of a known result-effective variable would be one, but not the only, motivation for a person of ordinary skill in the art to experiment to reach another workable product or process” (MPEP 2144.05 II B). As such, a prior art rejection does not have to rely on rationale associated with “result-effective variable”. Secondly, the rejections were/are based on teachings factually disclosed in prior arts of Cho, Park, Wilson and Cho-II, rather than “result-effect variable” rationale. Thus, the arguments are not convincing.
2) In response to Applicant’s arguments with respect to the newly added limitation about the size of Si nanoparticles, the new reference Cho-II has been introduced in this office action to address the claimed size of Si nanoparticles.
Further as to “… the capacity retention rate exhibits a significantly superior effect”, it is noted that the fact that applicant has recognized another advantage which would flow naturally from following the suggestion of the prior art cannot be the basis for patentability when the differences would otherwise be obvious. See Ex parte Obiaya, 227 USPQ 58, 60 (Bd. Pat. App. & Inter. 1985).
Conclusion
Any inquiry concerning this communication or earlier communications from the examiner should be directed to ZHONGQING WEI whose telephone number is (571)272-4809. The examiner can normally be reached Mon - Fri 9:30 - 6:00.
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/ZHONGQING WEI/
ZHONGQING WEI, Ph.D.Primary Examiner, Art Unit 1727