PREPARATION METHOD OF HIGH-RATE LITHIUM IRON PHOSPHATE POSITIVE ELECTRODE MATERIAL
DETAILED ACTION
Status of Claims
Claims 1 and 10-12 have been amended. Claims 1, 3-5 and 9-12 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Any rejections and/or objections made in the previous Office Action and not repeated below, are hereby withdrawn in view of Applicant’s amendments or/and arguments.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.
Information Disclosure Statement
The information disclosure statement (IDS) submitted on Jan. 19, 2026 has been considered by the examiner.
The listing of references in the Applicant’s arguments and remarks filed on Feb. 6, 2026 is not a proper information disclosure statement. 37 CFR 1.98(b) requires a list of all patents, publications, or other information submitted for consideration by the Office, and MPEP § 609.04(a) states, "the list may not be incorporated into the specification but must be submitted in a separate paper." Therefore, unless the references have been cited by the examiner on form PTO-892, they have not been considered.
Claim Rejections - 35 USC § 112
Claim 12 is rejected under 35 U.S.C. 112(a) or 35 U.S.C. 112 (pre-AIA ), first paragraph, as failing to comply with the written description requirement. The claim(s) contains subject matter which was not described in the specification in such a way as to reasonably convey to one skilled in the relevant art that the inventor or a joint inventor, or for applications subject to pre-AIA 35 U.S.C. 112, the inventor(s), at the time the application was filed, had possession of the claimed invention.
The limitation “a mean particle size of 100 nm” in claim 12 is not supported by the specification as originally filed. The paragraph [0008], pointed out by the Applicant, of the specification as originally filed does not support this limitation.
Claim 1, 3-5 and 9-12 are rejected under 35 U.S.C. 112(b) or 35 U.S.C. 112 (pre-AIA ), second paragraph, as being indefinite for failing to particularly point out and distinctly claim the subject matter which the inventor or a joint inventor (or for applications subject to pre-AIA 35 U.S.C. 112, the applicant), regards as the invention.
Before the above written-description 112(a) rejection is overcome, the previous 112(b) rejection regarding the limitation “a bulk material of the anhydrous iron phosphate has a honeycomb structure” is maintained in this office action.
The limitation “a bulk material of the anhydrous iron phosphate has a honeycomb structure” remain recited in claim 1 is ambiguous, rendering the claims indefinite. This recitation is not clearly defined, disclosed, or/and claimed. A few possibilities for interpreting the recitation are as follows:
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Applicant is required to clarify which the recitation refers to or what the invention is intended to claim in relation to “honeycomb structure”, and is required to point out where the support is in the specification as originally filed. Note that the above configurations represent hypotheses but do not necessarily represent a configuration of the instant invention. Applicant is required to clarify the limitation “a bulk material of the anhydrous iron phosphate has a honeycomb structure”.
Where applicant acts as his or her own lexicographer to specifically define a term of a claim contrary to its ordinary meaning, the written description must clearly redefine the claim term and set forth the uncommon definition so as to put one reasonably skilled in the art on notice that the applicant intended to so redefine that claim term. Process Control Corp. v. HydReclaim Corp., 190 F.3d 1350, 1357, 52 USPQ2d 1029, 1033 (Fed. Cir. 1999). The original specification merely mentions the term “honeycomb structure” three times (including once in claims) but does not specifically redefine the term. No specific details are provided in the instant disclosure for the said limitation.
Additionally, it is unclear why the shape of honeycomb structure is significant since the shape would not maintain during and after ball milling or/and sand-grinding.
In response to the previous 112(b) rejection (dated 11/20/2025) with respect to the limitation “a bulk material of the anhydrous iron phosphate has a honeycomb structure” recited in claim 1, Applicant argues that the term “honeycomb structure” has a well-established definition. This is not found persuasive.
The reference CN 118183654 A cited by the Applicant in the Remarks was filed and published in the year 2024, much later than the effective filing date of the instant invention. The reference CN 108455553 B was published before the effective filing date of the instant invention, but this only one reference is not sufficient to establish that the term “honeycomb structure” of the lithium iron phosphate positive electrode material has a well-established definition (not well-known).
Claim Rejections - 35 USC § 103
Claims 1, 3-5, and 9-12 are rejected under 35 U.S.C. 103 as being unpatentable over Fan et al. (CN 111313010 A) in view of Ren (CN 108455553 A), Liu et al. (CN 108455547 A) and Shen et al. (CN 104134801 A). The English machine translations of the four Chinese prior arts are being employed for citation purposes, hereafter referred to as Fan, Ren, Liu, and Shen, respectively.
Regarding claim 1, Fan teaches a high-temperature solid-phase method (See [0012]) for producing a lithium iron phosphate positive electrode material (See, at least, Abstract), comprising:
A) weighing an iron source (e.g., “iron phosphate”) and a lithium source (e.g., “lithium carbonate”) according to a certain molar ratio, then weighing a certain mass of a carbon source (e.g., “glucose”) and an ion doping agent (e.g., “titanium dioxide”), adding pure water (e.g., “deionized water”) to a mixture of the iron source, the lithium source, the carbon source and the ion doping agent to prepare a slurry with a certain solid content (e.g., “solid content is controlled at 45%”), and ball milling the slurry (See at least [0021]);
B) transferring the ball-milled slurry to a sand grinder for sand grinding (“ultra-fine mill”, [0021]), so that the particle size D50 after the sand grinding is controlled to be 600 nm and below ([0021]);
C) spray-drying the slurry after the sand grinding (“spray drying”, [0021]) to obtain a pale yellow precursor powder (Note that the pale yellow color is reasonably expected because raw materials and steps to process the raw materials in Fan and in claim 1 are substantially the same);
D) putting the precursor into a sintering furnace for sintering at a high temperature of 750 [Symbol font/0xB0]C under the protection of nitrogen gas for 6 h, and cooling to obtain a sintered material ([0022]). The 750 [Symbol font/0xB0]C is close to the upper limit of the claimed range, and thus a prima facie case of obviousness exists where the claimed ranges or amounts do not overlap with the prior art but are merely close. The limitation “cooling to obtain a sintered material” is implicitly taught (e.g., before further processing such as pulverizing and using in forming a battery). See MPEP § 2144.05. This step D is further addressed below; and
E) pulverizing the sintered material and sieving the pulverized material (“crushed and classified”, [0023]) to obtain the lithium iron phosphate positive electrode material.
As for the step A, Fan disclose that the iron source is anhydrous iron phosphate (claim 3 of Fan). Fan is silent as to a bulk material of the anhydrous iron phosphate having a honeycomb structure. In the same field of endeavor, however, Ren discloses that a lithium iron phosphate prepared from iron phosphate having a honeycomb-shaped structure can be in sufficient contact with electrolyte, and “a lithium ion diffusion path is shortened, so that the rate performance and low-temperature performance of a material are remarkable improved” (Abstract). Thus, one of ordinary skill in the art would have used anhydrous iron phosphate with a honeycomb-shaped structure in the preparation of lithium iron phosphate of Fan, as taught by Ren, in order to achieve benefits stated above.
As to a BET of 9-11 m2/g as claimed, Fan discloses that the BET surface area is in the range of 2-8 m2/g (claim 3), and thus the higher limit of the range is close to the lower limit of the range as claimed. A prima facie case of obviousness exists where the claimed ranges or amounts do not overlap with the prior art but are merely close. See MPEP § 2144.05 (I). Alternatively, most of the anhydrous iron phosphates on the market have a specific surface area of 7-10 m2/g, as evidenced by Liu ([0008]). One of ordinary skill in the art would readily appreciate that the said anhydrous iron phosphates on the market can also be used as an alternative to the anhydrous iron phosphate of Fan having a BET surface area of 2-8 m2/g during the process of producing lithium iron phosphate positive electrode material, since the anhydrous iron phosphates having a BET surface area of 7-10 m2/g is commercially available. As a result, the range 7-10 m2/g teaches that of 9-11 m2/g as claimed.
As for the step B, the claimed range of 100-200 nm lies inside the range of “600 nm and below” disclosed by Fan. 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).
As for the step C, Fan as modified teaches the spray-drying is carried out under an air inlet temperature of a spray-drying machine of 300 [Symbol font/0xB0]C and an air outlet temperature of the spray-drying machine of 95 [Symbol font/0xB0]C ([0021]). Note that 300 [Symbol font/0xB0]C is close to 280 [Symbol font/0xB0]C as claimed. A prima facie case of obviousness exists where the claimed ranges and prior art ranges do not overlap but are close enough. Titanium Metals Corp. of Amer. v. Banner, 778 F.2d 775, 227 USPQ 773 (Fed. Cir. 1985). See at least MPEP 2144.05 (I). Note also that generally, differences in temperature will not support the patentability of subject matter encompassed by the prior art unless there is evidence indicating such temperature is critical. See MPEP § 2144.05 II A.
Applicant argues about an insignificant difference of air inlet temperature between Fan’s 300 [Symbol font/0xB0]C and the claimed upper limit of 280 [Symbol font/0xB0]C in the Step C. Applicant also argues about insignificant differences in temperature and time employed in the Step D between Fan and the instant invention. However, unless there are evidences indicating these parameters (sintering temperature, sintering time, and inlet and outlet temperatures of spray-drying machine) are critical, they have little patentable weight (not patentably distinguishable) because a selection of the said parameters with certain values is a matter of design choice. One of ordinary skill in the art would have readily arrived at the claimed parameters through routine experimentations. As one of numerous examples, Shen discloses a similar preparation process, wherein an air inlet temperature of a spray-drying machine is in a range of 170 [Symbol font/0xB0]C to 300 [Symbol font/0xB0]C, an air outlet temperature of the spray-drying machine is in a range of 80 [Symbol font/0xB0]C to 95 [Symbol font/0xB0]C, a sintering temperature is in a range of 600 [Symbol font/0xB0]C to 900 [Symbol font/0xB0]C, a sintering time is in a range of 2 hours to 20 hours (See, at least, claim 3 of Shen), and a protection gas is nitrogen gas (at least, [0026]). All the claimed ranges in Steps C and D overlap those above disclosed in Shen, respectively. 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).
It is also noted that "It is a settled principle of law that a mere carrying forward of an original patented conception involving only change of form, proportions, or degree, or the substitution of equivalents doing the same thing as the original invention, by substantially the same means, is not such an invention as will sustain a patent, even though the changes of the kind may produce better results than prior inventions.". See MPEP § 2144.05.
Regarding claim 3, Fan as modified teaches the method for producing a lithium ion phosphate positive electrode material according to claim 1, wherein the molar ratio of the iron source to the lithium source can be 1:1.01 to 1:1.02 (Claim 1 of Fan). The instantly claimed range of 1:1 to 1:1.05 overlaps the above range. 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 4, Fan as modified teaches the method for producing a lithium ion phosphate positive electrode material according to claim 1, wherein the carbon source may be glucose ([0021], Fan).
Regarding claim 5, Fan as modified teaches the method for producing a lithium ion phosphate positive electrode material according to claim 1, wherein the metal ion doping agent may be titanium dioxide ([0021]).
Regarding claim 9, Fan as modified teaches the method for producing a lithium ion phosphate positive electrode material according to claim 1, and teaches the pulverizing step ([0023], Fan). Thus, one of ordinary skill in the art would readily arrive at the claimed particle size D50 of the sintered material after pulverizing by controlling the level or degree of pulverizing through routine experimentation.
Regarding claim 10, Fan as modified teaches the method for producing a lithium ion phosphate positive electrode material according to claim 1, wherein the carbon source is in an amount from about 5% by mass of the iron source and the lithium source based on a calculation using the data disclosed in paragraph [0021] of Fan.
Regarding claim 11, Fan as modified teaches the method for producing a lithium ion phosphate positive electrode material according to claim 1, wherein the ion doping agent is in an amount from about 0.35% by mass of the iron source and the lithium source based on a calculation using the data disclosed in paragraph [0021] of Fan.
Regarding claim 12, Fan as modified teaches the method for producing a lithium ion phosphate positive electrode material according to claim 1, wherein the lithium iron phosphate positive electrode material has a primary particle having a particle size of about 100 nm. See an example below:
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Response to Arguments
Applicant's arguments and declaration filed on Feb. 6, 2026 have been fully considered but they are not persuasive.
Applicant's arguments are based on the claims as amended. The amended claims have been addressed in the new rejections above. In addition,
1) A response to the arguments regarding “honeycomb structure” has been incorporated in the above rejection of claim 1.
2) The “spheroidal-like” in the table of the arguments is not claimed.
3) Applicant’s arguments with respect to the “effect(s)” and “impact(s)” of the shape of a honeycomb structure represent Applicant’s opinion or/and allegation, which is not supported by factual evidence.
4) In response to applicant's arguments against the references individually (for example, the LIU reference), one cannot show nonobviousness by attacking references individually where the rejections are based on combinations of references. See In re Keller, 642 F.2d 413, 208 USPQ 871 (CCPA 1981); In re Merck & Co., 800 F.2d 1091, 231 USPQ 375 (Fed. Cir. 1986).
5) To simplify the response to Applicant’s arguments and better address the claim limitations, this office action has introduced a new reference SHEN and removed the ZHOU reference.
6) On page 6/13, Applicant mentioned “see Appendix 2”. It is unclear what it is and where it is. Note again that all references should be submitted in an IDS.
Conclusion
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.
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