Prosecution Insights
Last updated: July 17, 2026
Application No. 17/914,252

LITHIUM IRON PHOSPHATE POSITIVE ELECTRODE SHEET, PREPARATION METHOD THEREFOR, AND LITHIUM IRON PHOSPHATE LITHIUM-ION BATTERY

Non-Final OA §103
Filed
Sep 23, 2022
Priority
Mar 25, 2020 — CN 202010219542.3 +1 more
Examiner
ARMSTRONG, KAREN JOYCE
Art Unit
1726
Tech Center
1700 — Chemical & Materials Engineering
Assignee
BYD Company Limited
OA Round
3 (Non-Final)
64%
Grant Probability
Moderate
3-4
OA Rounds
0m
Est. Remaining
84%
With Interview

Examiner Intelligence

Grants 64% of resolved cases
64%
Career Allowance Rate
18 granted / 28 resolved
-0.7% vs TC avg
Strong +20% interview lift
Without
With
+19.5%
Interview Lift
resolved cases with interview
Typical timeline
3y 5m
Avg Prosecution
43 currently pending
Career history
89
Total Applications
across all art units

Statute-Specific Performance

§101
1.2%
-38.8% vs TC avg
§103
95.3%
+55.3% vs TC avg
§102
3.5%
-36.5% vs TC avg
Black line = Tech Center average estimate • Based on career data from 28 resolved cases

Office Action

§103
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 . 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and the fee set forth in 37 CFR 1.17(e) has been timely paid, the finality of the previous Office action has been withdrawn pursuant to 37 CFR 1.114.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 02/09/2026 has been entered. Response to Amendment The amendment filed on 02/09/2026 does not place the application in condition for allowance. The basis of the rejection of claims 1-4, 8-13 and 15-20 under 35 U.S.C. 103 is maintained. Response to Arguments Applicant's arguments filed 09/18/2025 have been fully considered but they are not persuasive. In response to applicants’ argument that Huang does not specify 2-10% of particles in the range 1-10 µm, while the examiner agrees Huang does not specifically point out this range they reference 1 µm multiples times, for example in paragraph 89 where the material has an D97 of 1 µm leading one of ordinary skill in the art to conclude there are particles in the claimed range of 1-10 µm. In response to applicants’ argument Huang teaches away from the claimed invention by referring to “nano particles” to describe their invention, the examiner points out both the claimed invention by the applicant and Huang clearly include 1000 nm (1 µm) in their invention leading to clear inclusion of the claimed invention in the disclosure of Huang. Applicant also argues there is no motivation to combine Huang and Hennige and the porosity of Hennige is not relevant to the material of Huang. Huang and Hennige both teach lithium iron phosphate as a positive electrode active material and Hennige further teaches the porosity leads to higher surface area which is desirable in the invention of Huang(see current rejection of claim 1). 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. 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 and 2 are rejected under 35 U.S.C. 103 as being unpatentable over Huang (US20130143114 as cited in IDS dated 11/20/24) in view of Hennige et. al. (US20050221192). Regarding claims 1 and 2, Huang discloses a lithium iron phosphate cathode material (¶[0007) that is intended to be used in a cathode sheet within a battery (abstract). Huang also discloses the lithium iron phosphate has a particle size distribution D10 is about 50 nm, D50 is about 200 nm, D90 is about 700 nm, and D97 is about 900 nm (¶[0051]-[0058]), which one of ordinary skill in the art would recognize leaves 3% of the particles with particles sizes above 900 nm and the 80% of the particles with particles sizes between 50 and 700 nm and 7% of the particles with particles sizes between 700 and 900 nm. Therefore, it would have been obvious the ranges of Huang meet the claimed ranges of claim 1 and any small variation would not result in different properties.[A] prima facie case of obviousness exists where the claimed ranges or amounts do not overlap with the prior art but are merely close. Titanium Metals Corp. of America v. Banner, 778 F.2d 775, 783, 227 USPQ 773, 779 (Fed. Cir. 1985). "The proportions are so close that prima facie one skilled in the art would have expected them to have the same properties.”. MPEP §2144.05.I. In the alternative, if it can be shown the above ranges are different than the claimed ranges Huang also teaches the optimization of the size distribution of the particles and thus surface area through variation of the sintering and milling steps (table ¶[0110] and ¶[0111]). One of ordinary skill in the art would have recognized modifying the particle sizes results in improving conductivity and capacity characteristics of the material (¶[0023]). Therefore it would have been obvious to one of ordinary skill in the art to modify a percentage of the lithium phosphate particles to the particle sizes in the range of 50 nm-500 nm is 75-87%, 500 nm-1000 nm is 8-17%, 1 μm-10 μm is 3-7% to provide improved conductivity and capacity. “[W]here the general conditions of a claim are disclosed in the prior art, it is not inventive to discover the optimum or workable ranges by routine experimentation.” See In re Aller, 220 F.2d 454, 456, 105 USPQ 233, 235 (CCPA 1955). The discovery of an optimum value of a known result effective variable, without producing any new or unexpected results, is within the ambit of a person of ordinary skill in the art. See In re Boesch, 205 USPQ 215 (CCPA 1980) (see MPEP § 2144.05, II.). Huang does not disclose and wherein the lithium iron phosphate cathode sheet has a porosity of 20%-30%, measured by mercury porosimeter test method. Hennige, related to electrodes for lithium ion batteries, teaches a lithium iron phosphate material with a porosity of 20-40% determined by Hg porosimetry(¶[0038]). One of ordinary skill in the art would have recognized the porosity taught by Hennige would lead to a high surface area(¶[0038] of Hennige) and this is desirable as it improves the conductivity and characteristics of the cathode material as taught by Huang(¶[0023]). Therefore, it would have been obvious to one of ordinary skill in the art to have set the porosity of Huang to the range taught by Hennige to improve the characteristics of the electrode material. In the case where the claimed ranges “overlap or lie inside ranges disclosed by the prior art” a prima facie case of obviousness exists. In re Wertheim, 541 F.2d 257, 191 USPQ 90 (CCPA 1976); In re Woodruff, 919 F.2d 1575, 16 USPQ2d 1934 (Fed. Cir. 1990). MPEP §2144.05. Claims 3-4, 8-13 and 15-20 are rejected under 35 U.S.C. 103 as being unpatentable over Huang (US20130143114 as cited in IDS dated 11/20/24), in view of Hennige et. al. (US200500221192) and further in view of Zixiang et. al. (CN108172830 as cited in IDS dated 11/20/24, reference made to attached English translation). Regarding claim 3, modified Huang discloses a lithium phosphate cathode sheet according to claim 1, but does not explicitly disclose wherein a compacted density of the lithium iron phosphate cathode sheet is 2.6 g/cm3-2.8 g/cm3, an areal density of the lithium iron phosphate cathode sheet is 380 g/m2-420 g/m2. Zixiang, related to positive electrode material teaches a lithium iron phosphate active material with a compaction density of 2.4 g/cm3 -2.7 g/cm3 b(¶[0028]) and a surface density 184 g/m2 before removing the solvent which results in a final areal density of over 400 g/m2---. One of ordinary skill in the art would have recognized applying the density teaching of Zixiang to the cathode sheet of modified Huang would result in electrode material performance and energy density(¶[0028]). Therefore, it would have been obvious to have applied the density teaching of Zixiang to the cathode sheet of modified Huang to improve electrode material performance and energy density. In the case where the claimed ranges “overlap or lie inside ranges disclosed by the prior art” a prima facie case of obviousness exists. In re Wertheim, 541 F.2d 257, 191 USPQ 90 (CCPA 1976); In re Woodruff, 919 F.2d 1575, 16 USPQ2d 1934 (Fed. Cir. 1990). MPEP §2144.05. Regarding claim 4, modified Huang discloses a lithium phosphate cathode sheet according to claim 1, but does not disclose a binder or conductive agent. Zixiang, related to positive electrode materials, teaches a lithium iron phosphate mixed with polyvinylidene fluoride (PVDF) as a biner and carbon nanotubes (CNT) as a conductive agent in a ratio of 95:2.5:1 (¶[0066]). One or ordinary skill in the art would have recognized adding ratios of lithium iron phosphate, binder and conductive agent of Zixiang with the material of Huang would have created a cathode sheet with a high specific capacity and long life cycle (¶[0028]). Therefore, it would have been obvious to one of ordinary skill in the art to have used the material ratios of Zixiang with the lithium iron phosphate of Huang to gain a high specific capacity and long life cycle. Regarding modified claim 8, Huang discloses a lithium phosphate cathode sheet according to claim 1, but does not explicitly disclose a battery. Zixiang, related to positive electrode material teaches a lithium iron phosphate active material used in a lithium ion battery (¶[0065]). One of ordinary skill in the art would have recognized adding the cathode material of Huang into a lithium ion battery would have created a functioning battery as suggested by Huang (abstract of Huang). Therefore, it would have been obvious to have added the cathode material of Huang into a lithium ion battery to create a functioning battery. Regarding claim 9, modified Huang discloses a lithium phosphate cathode sheet according to claim 8, but does not disclose wherein a volumetric energy density of the lithium iron phosphate battery is 260 KWh/m3-280 KWh/m3, and a weight energy density of the lithium iron phosphate battery is 190 Wh/kg-210 Wh/kg. Zixiang, related to positive electrode material teaches a lithium iron phosphate active material with a compaction density of 2.4 g/cm3 -2.7 g/cm3 b(¶[0028]) and a surface density 184 g/m2 before removing the solvent which results in a final areal density of over 400 g/m2. One of ordinary skill in the art would recognize a lithium iron phosphate battery with a cathode sheet of Huang having a compacted density and areal density according to Zixiang would lead to a volumetric energy density and weight energy density in the claimed ranges of 260 KWh/m3-280 KWh/m3 and 190 Wh/kg-210 Wh/kg respectively and applying the density teaching of Zixiang to the cathode sheet of modified Huang would result in electrode material performance and energy density(¶[0028]). Therefore, it would have been obvious to have applied the density teaching of Zixiang to the cathode sheet of modified Huang to improve electrode material performance and energy density. In the case where the claimed ranges “overlap or lie inside ranges disclosed by the prior art” a prima facie case of obviousness exists. In re Wertheim, 541 F.2d 257, 191 USPQ 90 (CCPA 1976); In re Woodruff, 919 F.2d 1575, 16 USPQ2d 1934 (Fed. Cir. 1990). MPEP §2144.05. Regarding claim 10, Huang discloses a lithium phosphate cathode sheet according to claim 1, but does not explicitly disclose wherein a compacted density of the lithium iron phosphate cathode sheet is 2.6 g/cm3-2.8 g/cm3, an areal density of the lithium iron phosphate cathode sheet is 380 g/m2-420 g/m2. Zixiang, related to positive electrode material teaches a lithium iron phosphate active material with a compaction density of 2.4 g/cm3 -2.7 g/cm3 b(¶[0028]) and a surface density 184 g/m2 before removing the solvent which results in a final areal density of over 400 g/m2. One of ordinary skill in the art would have recognized applying the density teaching of Zixiang to the cathode sheet of modified Huang would result in electrode material performance and energy density(¶[0028]). Therefore, it would have been obvious to have applied the density teaching of Zixiang to the cathode sheet of modified Huang to improve electrode material performance and energy density. In the case where the claimed ranges “overlap or lie inside ranges disclosed by the prior art” a prima facie case of obviousness exists. In re Wertheim, 541 F.2d 257, 191 USPQ 90 (CCPA 1976); In re Woodruff, 919 F.2d 1575, 16 USPQ2d 1934 (Fed. Cir. 1990). MPEP §2144.05. Regarding claim 11, modified Huang discloses a lithium phosphate cathode sheet according to claim 2, but does not disclose a binder or conductive agent. Zixiang, related to positive electrode materials, teaches a lithium iron phosphate mixed with polyvinylidene fluoride (PVDF) as a binder and carbon nanotubes (CNT) as a conductive agent in a ratio of 95:2.5:1 (¶[0066]). One or ordinary skill in the art would have recognized adding ratios of lithium iron phosphate, binder and conductive agent of Zixiang with the material of Huang would have created a cathode sheet with a high specific capacity and long life cycle (¶[0028]). Therefore, it would have been obvious to one of ordinary skill in the art to have used the material ratios of Zixiang with the lithium iron phosphate of Huang to gain a high specific capacity and long life cycle. Regarding claim 12, modified Huang discloses a lithium phosphate cathode sheet according to claim 3, but does not explicitly disclose a binder or conductive agent. Zixiang, related to positive electrode materials, teaches a lithium iron phosphate mixed with polyvinylidene fluoride (PVDF) as a biner and carbon nanotubes (CNT) as a conductive agent in a ratio of 95:2.5:1 (¶[0066]). One or ordinary skill in the art would have recognized adding ratios of lithium iron phosphate, binder and conductive agent of Zixiang with the material of Huang would have created a cathode sheet with a high specific capacity and long life cycle (¶[0028]). Therefore, it would have been obvious to one of ordinary skill in the art to have used the material ratios of Zixiang with the lithium iron phosphate sheet of modified Huang to gain a high specific capacity and long life cycle. Regarding claim 13, modified Huang discloses a lithium phosphate cathode sheet according to claim 10, but does not disclose a binder or conductive agent. Zixiang, related to positive electrode materials, teaches a lithium iron phosphate mixed with polyvinylidene fluoride (PVDF) as a biner and carbon nanotubes (CNT) as a conductive agent in a ratio of 95:2.5:1 (¶[0066]). One or ordinary skill in the art would have recognized adding ratios of lithium iron phosphate, binder and conductive agent of Zixiang with the material of Huang would have created a cathode sheet with a high specific capacity and long life cycle (¶[0028]). Therefore, it would have been obvious to one of ordinary skill in the art to have used the material ratios of Zixiang with the lithium iron phosphate of Huang to gain a high specific capacity and long life cycle. Regarding claim 15, modified Huang discloses a lithium phosphate cathode sheet according to claim 2, Zixiang, related to positive electrode material teaches a lithium iron phosphate active material used in a lithium ion battery (¶[0065]). One of ordinary skill in the art would have recognized adding the cathode material of Huang into a lithium ion battery would have created a functioning battery as suggested by Huang (abstract of Huang). Therefore, it would have been obvious to have added the cathode material of Huang into a lithium ion battery to create a functioning battery. Regarding claim 16, modified Huang discloses a lithium phosphate cathode sheet according to claim 3, Zixiang, related to positive electrode material teaches a lithium iron phosphate active material made into a lithium ion battery (¶[0065]). One of ordinary skill in the art would have recognized adding the cathode material of Huang into a lithium ion battery would have created a functioning battery as suggested by Huang (abstract of Huang). Therefore it would have been obvious to have added the cathode material of Huang into a lithium ion battery to create a functioning battery. Regarding claim 17, modified Huang discloses a lithium phosphate cathode sheet according to claim 4, Zixiang, related to positive electrode material teaches a lithium iron phosphate active material made into a lithium ion battery (¶[0065]). One of ordinary skill in the art would have recognized adding the cathode material of Huang into a lithium ion battery would have created a functioning battery as suggested by Huang (abstract of Huang). Therefore, it would have been obvious to have added the cathode material of Huang into a lithium ion battery to create a functioning battery. Regarding claim 18, modified Huang discloses a lithium phosphate cathode sheet according to claim 10, Zixiang, related to positive electrode material teaches a lithium iron phosphate active material made into a lithium ion battery (¶[0065]). One of ordinary skill in the art would have recognized adding the cathode material of Huang into a lithium ion battery would have created a functioning battery as suggested by Huang (abstract of Huang). Therefore it would have been obvious to have added the cathode material of Huang into a lithium ion battery to create a functioning battery. Regarding claim 19, modified Huang discloses a lithium phosphate cathode sheet according to claim 11, Zixiang, related to positive electrode material teaches a lithium iron phosphate active material made into a lithium ion battery (¶[0065]). One of ordinary skill in the art would have recognized adding the cathode material of Huang into a lithium ion battery would have created a functioning battery as suggested by Huang (abstract of Huang). Therefore, it would have been obvious to have added the cathode material of Huang into a lithium ion battery to create a functioning battery. Regarding claim 20, modified Huang discloses a lithium phosphate cathode sheet according to claim 12, Zixiang, related to positive electrode material teaches a lithium iron phosphate active material made into a lithium ion battery (¶[0065]). One of ordinary skill in the art would have recognized adding the cathode material of Huang into a lithium ion battery would have created a functioning battery as suggested by Huang (abstract of Huang). Therefore it would have been obvious to have added the cathode material of Huang into a lithium ion battery to create a functioning battery. Conclusion Any inquiry concerning this communication or earlier communications from the examiner should be directed to KAREN J. ARMSTRONG whose telephone number is (703)756-1243. The examiner can normally be reached Monday-Friday 10 am-6 pm EST. Examiner interviews are available via telephone, in-person, and video conferencing using a USPTO supplied web-based collaboration tool. To schedule an interview, applicant is encouraged to use the USPTO Automated Interview Request (AIR) at http://www.uspto.gov/interviewpractice. If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Jeffrey Barton can be reached at (571) 272-1307. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300. Information regarding the status of published or unpublished applications may be obtained from Patent Center. Unpublished application information in Patent Center is available to registered users. To file and manage patent submissions in Patent Center, visit: https://patentcenter.uspto.gov. Visit https://www.uspto.gov/patents/apply/patent-center for more information about Patent Center and https://www.uspto.gov/patents/docx for information about filing in DOCX format. For additional questions, contact the Electronic Business Center (EBC) at 866-217-9197 (toll-free). If you would like assistance from a USPTO Customer Service Representative, call 800-786-9199 (IN USA OR CANADA) or 571-272-1000. /K.J.A./Examiner, Art Unit 1726 /RYAN S CANNON/Primary Examiner, Art Unit 1726
Read full office action

Prosecution Timeline

Sep 23, 2022
Application Filed
Jun 18, 2025
Non-Final Rejection mailed — §103
Sep 18, 2025
Response Filed
Nov 20, 2025
Final Rejection mailed — §103
Jan 15, 2026
Response after Non-Final Action
Feb 09, 2026
Request for Continued Examination
Feb 12, 2026
Response after Non-Final Action
Apr 17, 2026
Non-Final Rejection mailed — §103 (current)

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Study what changed to get past this examiner. Based on 5 most recent grants.

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Prosecution Projections

3-4
Expected OA Rounds
64%
Grant Probability
84%
With Interview (+19.5%)
3y 5m (~0m remaining)
Median Time to Grant
High
PTA Risk
Based on 28 resolved cases by this examiner. Grant probability derived from career allowance rate.

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