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 .
Response to Amendment
This is a final Office Action in response to Applicant’s remarks and amendments filed on 05/22/2026. Claims 1, 4, 6, 8, 13, 15, 17, and 19-20 are amended. Claim 2 is cancelled. Claims 3, 5, 7, 9, 10-12, 14, 16 and 18 are withdrawn. Claims 1, 4, 6, 8, 13, 15, 17, and 19-20 are pending in the current Office Action.
The objection to the specifications made of record in the previous Office Action mailed is withdrawn.
The objections to the claims made of record in the previous Office Action is withdrawn.
The 35 U.S.C 102 rejection set forth in the previous Office Action is withdrawn.
The 35 U.S.C. 103 rejections set forth in the previous Office Action are maintained with the rejections of claims 1 and 19 rewritten to address the amendments.
Response to Arguments
Applicant's arguments filed 05/22/2026 have been fully considered but they are not persuasive.
Applicant argues that the prior art, Kim, in view of Li and Liu, fails to disclose, teach, or suggest Element A of amended claim 1.
The Examiner notes that the rejection set forth in the previous Office Action does not rely on Kim in view of Li and Liu to reject Element A, as Element A and Element B of claim 2 were stated in the alternative, and Element B was rejected over Kim in view of Li and Liu.
Applicant further argues that the Office’s conclusion that the claimed particle size differences would have been obvious over Kim, Liu, and Li is based on improper hindsight and is not supported by the cited references. Specifically, Applicant argues that none of Kim, Li, or Liu disclose, suggest, or recognize controlling the differences between particle size distributions of two active material layers, or that such inter-layer particle size differences should fall within any particular range.
Liu teaches, as addressed in pgs. 7-8 of the previous Office Action, specific D10, D50, and D90 ranges for an LFP active material and further provides teachings as to why a skilled artisan would want to control the particle size and particle size distribution, such as wanting to balance electrochemical capacity, tap density, and processing properties. Thus, a skilled artisan would recognize that in utilizing the ranges taught by Liu, certain characteristics for LFP can be attained, and such particle sizes are common for LFP active materials to achieve such desired characteristics.
Similarly, Li teaches why a skilled artisan would desire to control the particle size of an NMC active material, as addressed in pages 8-9 of the previous Office Action, such as to achieve a balance between irreversible capacity, cycle life, and high-rate performance. A skilled artisan would further recognize that in using the particle sizes taught and suggested by Li, certain characteristics for NMC811 with Mn-rich shell can be attained and that such particle sizes are known in the art for such an active material.
Furthermore, Kim discloses a common configuration for an electrode which has different active materials on opposite sides of a current collector. As outlined one page 6 of the previous office action, Kim further discloses both LFP and NMC ternary materials to be acceptable active materials, evidencing that such materials are common in the art for positive electrodes as they are selected from a finite list provided by Kim ([0125]).
Thus, in light of the fact finding above, a skilled artisan has sufficient motivation to combine the teachings of Kim, Li, and Liu in order to benefit from the specific effects of each of the respective active materials, and thus would have reasonably arrived at the claimed ranges for the differences (i.e. ΔD10-, ΔD-50, and ΔD90 ) with reasonable expectation of achieving a successful positive active material layer.
Furthermore, the Examiner notes that even if the prior art does not explicitly disclose, suggest, or recognize controlling the difference between particle size distributions of the two active material layers, the specification of the instant application fails to present sufficient evidence that the claimed ranges for the differences in D10, D50, and D90, when separately or simultaneously controlled, result in any unexpected results or special technical effects that a skilled artisan would not predict based on the teachings of the prior art.
Thus, lacking unexpected results in the instant specification, the prima facie case of obviousness is maintained and the argument regarding hindsight is found not persuasive.
Applicant further argues that Li, particularly, does not disclose any particle size distribution or range and that the Office’s interpretation of Li is inconsistent with Li’s teaching.
As addressed in pg. 9 of the previous Office Action, Li suggests NMC811 core with a Mn-rich shell with a particle range of 1 to 10 µm through working embodiments. Even if Li does not explicitly state that particles closer to 10 µm exhibit smaller irreversibility capacity and improved life cycle and good high-rate performance, Li, nevertheless, still provides a skilled artisan motivation to control the particle size of NMC811 core with a Mn-rich shell. Furthermore, as taught by Liu (see previous office action, pg. 9, second full para.), a skilled artisan would expect uniform particle size distribution to provide benefits in tap density, cycle life, at the expense of processing properties. Thus, Applicant’s argument regarding Li’s teaching of particle size distribution is rendered unpersuasive.
Applicant further argues that the Office Action relied on a general relationship of D10 < D50 < D90 but does not show that the differences would inevitably or predictably fall within the claimed ranges.
As addressed on pg. 9, first full paragraph, of the previous Office Action, Li, through working examples, suggests a D50 range for an LFP active material depending on a skilled artisan desired balance between certain characteristics, and through this suggestion, provides a prima facie case of obviousness for D10 less than 10 µm and D90 greater than 10 µm, both of which allow for the claimed differences (i.e. ΔD10- and ΔD90) to be reasonably arrived at by one skilled in the art.
Furthermore, Applicant argues even if Li and Liu discloses particle-size effects, such teachings only relate to single-material optimization, specifically that there is no basis for concluding that the claimed particle size differences would have been routinely optimized.
As addressed on pg. 7-8 of the previous Office Action, Liu provides motivation for why a skilled artisan would want to optimize the particle size distribution of LFP, and further describes why uniform particle distribution is desirable (see previous Office Action pg. 9, second full paragraph) which can be further applied to Li’s taught NMC active material. As discussed above and in the previous Office Action on pg. 9, first full paragraph, Li provides motivation for why a skilled artisan would want to control the size of an NMC811 core with a Mn-rich shell. As the prior art teaches these particular sizes, a skilled artisan, in combining, would have arrived at the differences claimed through optimizing the individual active material particle sizes in order to achieve the individual desired effects of the respective active materials (i.e. LFP with balanced discharge, starting capacity, cycling capacity and processing properties, and NMC811 with Mn-rich shell that has irreversible capacity balanced with good cycle life and high-rate performance).
Thus, in light of the discussion above, the rejection made in view of the prior art: Kim, Li, and Liu is maintained with the rejection rewritten below to address the amended limitations.
Claim Rejections - 35 USC § 103
The text of those sections of Title 35, U.S. Code not included in this action can be found in a prior Office action.
Claims 1, 4, 6, 8, 15, 17, and 19-20 are rejected under 35 U.S.C. 103 as being unpatentable over Kim et al. (US 20150340732 A1), as applied to claim 1 above, in view of Li et al. (Effect of Spherical Particle Size on the Electrochemical Properties of Lithium Iron Phosphate) and Liu et al. (In Situ X-Ray Diffraction Study of Layered Li-Ni-Mn-Co Oxides: Effect of Particle Size and Structural Stability of Core-Shell Materials). {Examiner notes: All prior art was cited in previous Office Action mailed 02/24/2026}
Regarding claims 1, 6, 8, and 19, Kim discloses an electrode sheet (i.e. positive electrode, [0012]) comprising a current collector (i.e. positive electrode current collector, [0012]) having a first surface ([0012]) and a second surface ([0012]) opposite to the first surface ([0045]; Fig. 1), a first active material covering at least a part of the first surface (i.e. first positive active material disposed on a first surface of positive current collector, [0012]), and a second active material covering at least a part of the second surface (i.e. second positive active material disposed on a second surface of positive current collector, [0012]), as claimed in claim 1.
Kim further discloses an electrode sheet assembly (i.e. electrode structure, [0012]) comprising a separator (i.e. first separator, [0048]), and two electrode sheets (i.e. positive and negative electrode, [0048]), which are located at two sides of the separator (i.e. first separator disposed between positive electrode and negative electrode, [0048]) and have opposite polarities (i.e. positive and negative electrodes, [0048]), wherein at least one of the two electrode sheets (i.e. positive electrode, [0012]) comprises:
a current collector having a first surface ([0012]) and a second surface ([0012]) opposite to the first surface ([0045]; Fig. 1); a first active material layer covering at least a part of the first surface ([0012]; Fig. 1); a second active material covering at least a part of the second surface ([0012]); Fig 1), as claimed in claim 19.
Kim further discloses the electrode sheet is a positive electrode sheet (asymmetrical positive electrode, [0047]). Kim further discloses the first active material and the second active materials have different active materials ([0104]).
Kim further discloses the positive active material may be any material generally available as a positive active material in the art, including LiFePO4, ([0123];[0125]), thus rendering obvious the selection of LiFePO4 (LFP) for one of the first or second positive active material.
Therefore, while Kim does not have an explicit embodiment that utilizes LiFePO4 as a first active material, it would have still been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, to have selected LiFePO4 from the finite list of choices with reasonable expectation such a selection would result in a successful positive active material.
Kim discloses the positive active material may also be LiNi1-x-yCoxMnyO2 (where, 0 ≤ x ≤ 0.5 and 0 ≤ y ≤0.5) ([0123];[0125]), which is a ternary material, thus rendering obvious its selection for the second active material layer in order to ensure the desired difference in capacity per unit weight ([0106]) since LiFePO4 inherently possesses less capacity per unit weight.
Kim does not explicitly disclose desired particle size for the active material layers but is interested in optimizing and improving rate characteristics and capacity ([0007]) which the teachings of Liu and Li are also interested in. Kim does not explicitly disclose the ternary material to be specifically polycrystalline either.
Liu teaches a lithium iron phosphate active material including an embodiment with a D10 of 0.478, D50 of 1.407 µm, and D90 of 2.655 µm (Table 2, LFP-C). Liu teaches such an embodiment is able to achieve greater discharge and starting capacity, as well as a robust cycling capacity relative to samples with greater D50 values (pg. 555). The same embodiment also exemplified an increased discharge voltage plateau (Fig. 4a). Liu teaches smaller size of spherical particles allow for better sphericity and electrochemical capacity (pg. 555, col.2, last para.) Furthermore, Liu teaches a more uniform particle size distribution results in an improved tap density (p. 551, Col. 2, para.2; Fig. 2). However, Liu teaches the smaller the spherical particle size, the poorer the processing properties of the electrode and longer the processing time (p. 556, col. 2, last para.).
The D10 of 0.478 µm and D50 of 1.407 µm taught by Liu render obvious the claimed D10 range of greater than 0.4 µm, and D50 range of 0.8 to 4 µm of claim 6, respectively, for the reasons set forth above. The taught D90 value of 2.655 µm of Liu is measured to a high precision, is equivalent to 3 µm to one significant figure as claimed, and is sufficiently specific to render obvious the claimed D90 range of 3 – 10 µm of claim 6, for the reasons set forth above, since the instant specification does not point to a similar level of precision, nor is there any special definition regarding the desired level of precision.
Assuming, arguendo, applicant is able to convincingly argue 2.655 µm of the prior art is not the same as the claimed 3 µm, it would still be obvious as 2.655 µm and 3 µm are so close a skilled artisan would appreciate that the two values for D90 would produce the same result (MPEP 2144.05 I).
Additionally, Liu establishes acceptable ranges for D10, D50, and D90 between the samples LFP-B and LFP-C to be 0.478 to 2.480 µm, 1.407 to 5.694 µm, and 2.655 to 11.502 µm, respectively (Table 2).
The taught range of Liu for D50 of 1.407 µm to 5.694 µm overlaps with the claimed range of 0.8 to 4 µm of claim 6. Therefore, it would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, to have selected and optimized within the overlapping portion of the ranges for D-10 to achieve a desired balance between discharge, starting capacity, cycling capacity and processing properties for the LFP active material.
The taught range of Liu for D90 of 2.655 to 11.502 µm encompasses the claimed range of 3 to 10 µm of claim 6. Therefore, it would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, to have selected and optimized within the encompassed portion of the ranges for D90 to achieve a desired balance between discharge, starting capacity, cycling capacity and processing properties for the LFP active material layer.
Li teaches a ternary polycrystalline material (i.e. NMC811 core with Mn-rich shell) where Ni-rich materials such as NMC811 show excellent rate and high capacity but experience capacity loss when charged at high potentials and high reactivity with electrolyte when charged at elevated temperatures, which can be minimized with the addition of a Li- or Mn-rich shell (pg. 162).
Li further teaches samples with Li- and Mn-rich layered oxides with large particle sizes should have smaller irreversible capacity, and better cycle life but may sacrifice high-rate performance (pg. 169, col. 2, para. 2). Li teaches 10 µm active material particles made up of small primary particles which have been sintered in to a polycrystalline monolith have a high tap density and low specific surface area (pg. 164, col. 2, para.2), are able to achieve a greater charge and discharge capacity (pg. 165, col. 2), and a more stable discharge capacity over repeated cycles (pg. 165-166). Conversely, particles 1 µm in size exhibited dramatic capacity fading and larger irreversible capacity (pg. 166, para. 1).
While Li suggests a D50 range of 1 to 10 µm, Li further suggests a NMC811 core with Mn-rich shell closer to 10 µm in size will exhibit relatively small irreversible capacity, good cycle life as well as good high-rate performance (pg. 169, col.2, para. 2-3), thus rendering obvious the selection of the overlapping portion of the claimed D50 range of 8 to 12 µm. Furthermore, a skilled artisan would know D10 is necessarily less than D50 and D90 is necessarily greater than D50, such that D10 is less than 10 µm and a D90 greater than 10 µm which overlaps the claimed ranges, thus providing a prima facie case of obviousness to select the overlapping portions.
Li does not explicitly teach a D10 greater than 1.5 µm or a D90 of 18 to 34 µm, and is not explicitly concerned with a uniform particle size distribution. However, a skilled artisan would recognize that Li must necessarily and inherently possess a D10 and D90 as stated above. It is well known in the art, as taught by Liu, that uniform particle size distribution, in general, results in a highly improved tap density (Liu, pg. 551, col. 2, para. 2), and improved cycling life (Liu, Fig. 2 and 6(b)), but at the expense of processing properties (Liu, pg. 556, col. 2, last para.).
Therefore, in an effort to arrive at a desired balance between tap density, cycling life and processing properties, it would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, to have arrived at the claimed D10 range of greater than 1.5 µm and D-90 range of 18 to 34 µm of claim 8.
Based on the fact finding above, the combined prior art discloses/renders obvious an LFP D10 range of 0.478 to 2.480 µm, and a ternary polycrystalline material D10 greater than 1.5 µm, yielding a difference between D10 of active material particles to be greater than 0, which encompasses the claimed range of 1 to 3 µm of claim 1 and 19.
The combined prior art discloses/renders obvious an LFP D50 range of 1.407 to 4 µm and a ternary polycrystalline D50 range of 8 to 10 µm, yielding a difference between D50 of active material particles of 4 to 8.593 µm which overlaps with the claimed range of 2 to 5 µm of claim 1 and 19.
The combined prior art discloses/renders obvious an LFP D90 range of 3 to 10 µm, and a ternary polycrystalline D90 range of 18 to 34 µm, yielding a difference between D90 of active material particles to be 8 to 31 µm, which overlaps the claimed range of 3 to 25 µm of claim 1 sand 19.
Therefore, it would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, to have selected and optimized within the encompassed/overlapping portion of ranges for the difference in D-10, D50, and D90 - -between active material layer particles in order to achieve the desired balance between charge and discharge capacity, stable discharge capacity over repeated cycles, and processing properties.
Regarding claim 4, modified Kim discloses all limitations as set forth above.
Modified Kim discloses a density of the first and second positive active material may be in the range of about 3.0 to 4.2 g/cc and that density may be controlled by changing the temperature of the pressing roll when using the pressing roll to press the two surfaces of the current collector (Kim, [0019-0020];[0063];[0121]).
Modified Kim discloses the Ni-rich ternary polycrystalline material (i.e. NMC811), while having excellent rate capability and high capacity, experiences capacity loss when charged to high potential and high reactivity with the electrolyte when in the charge state at an elevated temperature (Li, pg. 162). In addition to the Mn-rich shell, to further ensure minimizing active material high reactivity with the electrolyte, a skilled artisan would appreciate a greater compacted density for the Ni-rich ternary polycrystalline material in order to reduce the effective surface area of the active material the electrolyte is in contact, thus reducing side reactions with the electrolyte, but at the expense of rate capability.
Modified Kim discusses LFP having poor electronic conductivity and lithium-ion diffusion conductivity, and a low compaction density which results in low volumetric surface energy (p. 549, col. 1, pg. 1). A skilled artisan would desire LFP to have a low compaction density to allow for a greater effective surface area in order to compensate for the poor conductivity and resulting low reaction rate, but at the expense of volumetric specific energy.
While modified Kim does not explicitly disclose the compacted density difference between active material layers, the totality of the prior art appears to possess a compacted density difference between active material layers that overlaps/encompasses/is within the claimed “greater than 0.8 g/cm-3” as it would have been obvious to optimize the compacted densities of the layers within the claimed range in order to achieve the desired balance between minimized side reactions, rate capability, and high capacity for the ternary polycrystalline active material layer, and the electronic conductivity, reactivity, and volumetric specific energy for the LFP active material layer.
Regarding claim 15, modified Kim discloses all limitations as set forth above.
Modified Kim discloses a current density of the active material layer may increase by using active materials having high capacity per unit weight (Kim, [0105]), wherein choosing different active materials with different weights for the two positive active material layers may achieve a greater current density for the positive electrode (Kim, [0105-0106]; [0122]).
Modified Kim further discloses the recited lithium iron phosphate and ternary polycrystalline materials (i.e. polycrystalline nickel cobalt manganese(811)). According to [72] of the instant specifications, lithium iron phosphate inherently exhibits a gram capacity of 100 to 160 mAh/g while [74] of the instant specification discloses a gram capacity range of polycrystalline NMC inherently being 165 to 211 mAh/g. This yields a difference in gram capacity between the different active material layers to be 5-111 mAh/g, significantly overlapping the claimed difference of 20-110 mAh/g such that the selection of the overlapping portion is prima facie obvious to one having ordinary skill in the art.
Regarding claim 17, modified Kim discloses all of the limitations as set forth above.
Modified Kim discloses a thickness of the first positive active material layer may be in a range of about 10 to about 110 µm, and the thickness of the second positive active material layer may be greater than the thickness of the first positive active material layer by 1 to about 4 or less times as thick as the thickness of the first positive active material layer (Kim, [0020]), yielding a possible difference between thickness of the first and second active material layer to be 10 to 400 µm which overlaps with the claimed range of 5 to 50 µm. Modified Kim further discloses the desire to control current density of each layer such that the current density of the second active material is greater than that of the first active material layer as this results in decreased battery resistance and improvement in life characteristics [0094-0095]). The current densities of the active material layers depend on the amount, i.e. thickness, of the active material in the active material layer ([0099]), and in being able to reach desired current density for the active material layers, high energy density and improved power output can be achieved.
Therefore, it would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, to have selected and optimized within the overlapping portion of the ranges for the difference in thickness between active material layers in order to achieve a positive electrode with improved power output and life characteristics while to decreasing battery resistance.
Regarding claim 20, modified Kim discloses all limitations as set forth above.
Modified Kim further discloses the positive and negative electrode current collector may be any material that has conductivity, and may be formed of at least one material selected from aluminum, copper, nickel, titanium, and surface treated stainless steel (Kim, [0133-0134]). Modified Kim further discloses the positive and negative current collector may be used in various forms including foils and the current collector may be constructed of a non-conductive material that is coated with a conductive material (Kim, [0134]).
Therefore, it would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, to have selected a metal foil current collector for either the positive or negative current collector, and a composite current for the other current collector, from the finite list of choices with reasonable expectation such a selection would result in a successful electrode sheet assembly.
Claim 13 is rejected under 35 U.S.C 103 as being unpatentable over Kim et al. (US 20150340732 A1) in view of Li et al. (Effect of Spherical Particle Size on the Electrochemical Properties of Lithium Iron Phosphate) and Liu et al. (In Situ X-Ray Diffraction Study of Layered Li-Ni-Mn-Co Oxides: Effect of Particle Size and Structural Stability of Core-Shell Materials), as applied to claim 1 above, and in further view of Lee et al. (US 20170155133 A1).
Regarding claim 13, modified Kim discloses all limitations as set forth above.
Modified Kim discloses a BET specific surface area for the LFP active material of 14.20 – 16.50 m2/g (Liu, Table 2, LFP-B and LFP-C), but is silent regarding a preferred specific surface area for the ternary polycrystalline active material. However, a skilled artisan would recognize the ternary polycrystalline active material of modified Kim must necessarily possess a specific surface area.
Lee teaches a similar ternary polycrystalline material (i.e. NMC) with a BET specific surface area of 0.1 to 1.9 m2/g where a BET specific surface area exceeding 1.9 m2/g results in reduced cohesion of the active material and increased resistance of the electrode while a BET specific surface area below 0.1 m2/g results in reduced dispersibility and capacity of the positive electrode active material ([0053]).
The disclosed prior art teaches BET specific surface areas of 14.20 to 16.50 m2/g and 0.1 to 1.9 m2/g for LFP and the ternary polycrystalline material, respectively, yielding a difference between the specific surface area of the two materials to be 12.3 to 16.4 m2/g which overlaps with the claimed range difference of 7 to 15 m2/g.
Therefore, it would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, to have selected and optimized the ternary polycrystalline material BET specific surface area, as well as the difference between the specific surface areas of the different active material layers for the benefit of a positive electrode with cohesion of the active material, reduced resistance, and increased dispersibility and capacity (MPEP 2144.05 II).
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.
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/E.J.T./Examiner, Art Unit 1751
/JONATHAN G LEONG/Supervisory Patent Examiner, Art Unit 1751 7/29/2026
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