Method for manufacturing a positive electrode for a non-aqueous electrolyte battery

Abstract

This suppresses the decline in output performance at the end of the lifespan of non-aqueous electrolyte batteries. [Solution] A method for manufacturing a positive electrode for a non-aqueous electrolyte battery, comprising the steps of: preparing positive electrode particles 10 having a core portion 11 mainly composed of a positive electrode active material and a coating layer 12 containing a lithium tungstate compound and covering the core portion 11; measuring the coating amount, which is the amount of the coating layer 12 per unit area of ​​the core portion 11; and kneading a mixture containing the positive electrode particles 10 and inorganic filler particles 13 according to the coating amount.

Description

Technical Field

[0001] The present disclosure relates to a method for manufacturing a positive electrode for a non-aqueous electrolyte battery.

Background Art

[0002] As a power source for an electric vehicle or a hybrid vehicle, a lithium-ion secondary battery, which is one of non-aqueous electrolyte secondary batteries, is used. Patent Document 1 describes positive electrode particles (positive electrode active material) provided with a coating portion in which tungsten is unevenly distributed. The coating portion is formed from an NCM lithium composite oxide phase containing tungsten. When the positive electrode particles contain tungsten, the reaction resistance of the positive electrode in the initial state of the battery decreases.

Prior Art Documents

Patent Documents

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, when the coating portion becomes thick, when the battery is stored at a high temperature, the amount of increase in resistance based on the initial state of the electrical resistance becomes large. And when the battery resistance thus increases, there is a possibility that the output performance at the end of the battery life decreases. ​​​​​​

[0006] In the coating layer described above, depressions (defects) occur due to uneven coating, and the core is exposed through these depressions. When the positive electrode active material contained in the core comes into contact with the non-aqueous electrolyte, a side reaction occurs in which the non-aqueous electrolyte decomposes, increasing the battery resistance. In contrast, when inorganic filler particles are added to the positive electrode material containing positive electrode particles, the inorganic filler particles block the depressions in the coating layer, thereby suppressing the decomposition of the non-aqueous electrolyte.

[0007] In the above manufacturing method, inorganic filler particles are kneaded together with positive electrode particles according to the amount of coating layer. Therefore, the increase in resistance caused by the thickness of the coating layer can be at least partially offset by the addition of inorganic filler particles. As a result, the decrease in output performance towards the end of the battery's lifespan can be suppressed. [Effects of the Invention]

[0008] According to this disclosure, it is possible to suppress the decline in output performance of a non-aqueous electrolyte battery at the end of its lifespan. [Brief explanation of the drawing]

[0009] [Figure 1] This figure schematically shows a cross-section of particles constituting a positive electrode for a non-aqueous electrolyte battery according to one embodiment of the present disclosure. [Figure 2] This graph shows the correlation between the amount of coating in the coating layer and the increase in resistance in the same embodiment. [Figure 3] This graph shows the correlation between the amount of inorganic filler particles added and the increase in resistance in the same embodiment. [Figure 4] This graph illustrates how to adjust the sum of the resistance increase due to the thickness of the coating layer and the resistance increase due to the decomposition of the electrolyte in this embodiment to an appropriate range. [Figure 5] This flowchart shows the procedure for manufacturing the positive electrode of the same embodiment. [Modes for carrying out the invention]

[0010] The following describes one embodiment of a method for manufacturing a positive electrode for a non-aqueous electrolyte battery. This embodiment is merely one example of an implementation for illustrative purposes of this disclosure and is not intended to limit the disclosure. In this embodiment, the non-aqueous electrolyte battery is described as a lithium-ion secondary battery.

[0011] Figure 1 shows positive electrode particles 10 manufactured using the manufacturing method of this embodiment. The positive electrode particles 10 are included in the positive electrode composite material. The positive electrode particles 10 have a core portion 11 and a coating layer 12 with a different composition from the core portion 11. The core portion 11 mainly consists of a positive electrode active material containing lithium. The coating layer 12 contains more tungsten than the core portion 11 and covers the core portion 11. In this embodiment, the coating layer 12 mainly consists of a lithium tungstate compound.

[0012] It is believed that the inclusion of a heteroatom oxide containing tungsten in the coating layer 12 forms a lithium ion conduction path between the core 11 and the electrolyte. This reduces the reaction resistance at the positive electrode. However, if the thickness of the coating layer 12 is excessive, excess tungsten ions will penetrate the transition metal layer of the positive electrode active material in the core 11. If nickel atoms (Ni) are present in the transition metal layer, this will lower the valence of the nickel atoms, resulting in divalent nickel atoms (Ni). 2+ The number of divalent nickel atoms increases. An increase in divalent nickel atoms accelerates the formation of nickel(II) oxide (NiO), making it more difficult for lithium ions to be inserted and removed. Even if nickel atoms are not present in the transition metal layer, oxides may similarly form for other transition metal elements. As a result, the resistance of lithium-ion secondary batteries increases when stored at high temperatures. The increase in battery resistance after high-temperature storage due to the thickness of the coating layer 12 is defined as the resistance increase ΔR1. The resistance increase is calculated by subtracting the initial DCIR from the DCIR of the battery after high-temperature storage (DCIR after storage - initial DCIR).

[0013] As shown in Figure 2, the resistance increase ΔR1 increases with increasing coating amount C, which is the amount of coating layer 12 per unit area of ​​the core portion 11. On the other hand, the coating layer 12 is formed by covering the core portion 11 with a compound containing tungsten. In this process, it is difficult for the coating layer 12 to cover the core portion 11 with a uniform thickness, resulting in inconsistencies in the thickness of the coating layer 12. Due to these inconsistencies in the coating layer 12, numerous recesses 16 (see Figure 1) are formed in the coating layer 12. Some of these recesses 16 expose the core portion 11.

[0014] When a positive electrode is created using positive electrode particles 10, which have numerous recesses 16 formed in the coating layer 12, and assembled as a lithium-ion secondary battery, the core portion 11 comes into contact with the electrolyte through some of the recesses 16. These recesses 16 can be described as defects in the coating layer 12. Contact between the core portion 11 and the electrolyte causes a side reaction in which the electrolyte is decomposed. When a film made of electrolyte decomposition products is formed on the positive electrode particles 10, it can increase the reaction resistance at the positive electrode. This increase in resistance is referred to here as the increase in battery resistance due to the side reaction, ΔR2.

[0015] In other words, as the coating amount C increases, the increase in battery resistance ΔR1 increases. Also, if the coating amount C is extremely small and many areas of the core 11 are exposed, the increase in resistance ΔR2 increases due to the progression of side reactions. Since the increase in resistance ΔR1 and ΔR2 are the increase in resistance due to each factor, the total increase in resistance of the battery is proportional to the sum of the increase in resistance ΔR1 and ΔR2.

[0016] The inventors found that when the positive electrode particles 10 and inorganic filler particles 13 are kneaded together with other additives during the manufacturing stage of the positive electrode, the resistance increase ΔR2 is reduced. Figure 3 shows the correlation between the addition amount of Al2O3 as the inorganic filler particles 13 and the resistance increase amount ΔR2. The coating amount C is constant. As can be seen from this graph, as the addition amount of Al2O3 increases, the resistance increase amount ΔR2 decreases. The reason is considered to be that the inorganic filler particles 13 reduce the contact area between the core part 11 and the electrolyte by closing the concave part 16. The occlusion by the inorganic filler particles 13 is not limited to the inorganic filler particles 13 being accommodated in the concave part 16 as shown in FIG. 1, but also includes inhibiting the flow of the electrolyte through the concave part 16 by closing a part of the opening near the opening of the concave part 16. Hereinafter, the positive electrode particles 10 provided with the inorganic filler particles 13 as shown in FIG. 1 are referred to as positive electrode particles 10A with filler, and when explaining without distinguishing the two, they are simply referred to as positive electrode particles 10.

[0017] Graphs 100 and 101 in FIG. 4 show the resistance increase amounts ΔR1 and ΔR2 at the end of the life of the lithium-ion secondary battery. As shown in Graph 100, the sum of the resistance increase amount ΔR1 due to the thickness of the coating layer 12 and the resistance increase amount ΔR2 due to the unevenness of the coating layer 12 may be within an appropriate range.

[0018] However, as shown by the resistance increase amount ΔR1 in Graph 101 of FIG. 4, the resistance increase amount ΔR1 due to the thickness of the coating layer 12 may increase according to the positive electrode particles 10 used in the production of the positive electrode. In this case, if the positive electrode particles 10 are directly used as the positive electrode composite material, the sum of the resistance increase amount ΔR1 and the resistance increase amount ΔR2 will exceed the appropriate range. Therefore, the inventor focused on the fact that by adding the inorganic filler particles 13, the resistance increase amount ΔR2 can be reduced as shown in Graph 101, and the sum of the resistance increase amounts ΔR1 and ΔR2 can be reduced as a whole. Thereby, even if the resistance increase amount ΔR1 increases, the sum of the resistance increase amount ΔR1 and the resistance increase amount ΔR2 can be kept within the appropriate range.

[0019] [Lithium-ion secondary battery] The lithium-ion secondary battery using the positive electrode particles 10 will be specifically described. The positive electrode includes a positive electrode current collector and a positive electrode composite material layer. The positive electrode current collector is a metal foil such as aluminum. The positive electrode composite material layer may contain, in addition to the positive electrode particles 10, a conductive material, a binder, and the like.

[0020] The positive electrode active material contained in the core part 11 of the positive electrode particles 10 is a layered or spinel-type lithium composite metal oxide. As the lithium composite metal oxide, lithium nickel cobalt manganese composite oxide (LNCM) can be used. LNCM contains at least one transition metal element selected from at least Li, Co, Ni, and Mn, and O. For example, LNCM may be represented by the general formula LiNixCoyMnzO2 (0 < x < 1, 0 < y < 1, 0 < z < 1, x + y + z = 1). Or, LiNiCoMnO2 may be used as the lithium nickel cobalt manganese composite oxide. Also, the ratio of Ni, Co, and Mn may be 50:20:30. LNCM may contain a transition metal element other than Ni, Co, and Mn, and a typical metal element other than Li. The positive electrode active material in the core part 11 preferably contains 50% by mass or more of LNCM, and more preferably 80% by mass or more. The positive electrode active material may be composed only of LNCM. As other positive electrode active materials, at least one of lithium manganese composite oxides such as LiMn2O4, lithium nickel composite oxides such as LiNiO2, lithium cobalt composite oxides such as LiCoO2, LiFeO2, LiCrMnO4, LiFePO4, etc., can be used. The positive electrode active material may contain tungsten (W) to such an extent that it does not inhibit the insertion and desorption of Li. The positive electrode active material is not limited to the above, and materials used in general lithium ion secondary batteries can be used.

[0021] The positive electrode active material may contain tungsten. For example, the positive electrode active material may be composed of an NCM lithium composite oxide containing tungsten (W). The coating layer 12 is mainly composed of lithium tungstate (Li2WO4). The coating layer 12 may contain 50% by mass or more of lithium tungstate relative to the total coating layer 12, and may also contain 80% by mass or more. The coating layer 12 may also contain Li4WO5 and Li6W2O9. The coating layer 12 may also contain other transition metal elements such as zirconium (Zr) as minor components. The coating layer 12 may be composed solely of lithium tungstate. Furthermore, it is preferable that the lithium tungstate content is 0.5% by weight or more and 3.0% by weight or less relative to the total weight of all positive electrode particles 10 contained in the positive electrode composite material.

[0022] For example, the conductive material can be conductive carbon such as acetylene black, and the binder can be polyvinylidene fluoride (PVDF), etc. The solvent used when mixing the positive electrode composite material can be N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), etc. These materials are not limited to those mentioned above, and materials commonly used in lithium-ion secondary batteries can be used.

[0023] The tungsten content in the coating layer 12 is preferably 1.0% by weight or more and 2.0% by weight or less. The content is the ratio of the weight of tungsten contained in the positive electrode composite material to the total weight of all positive electrode particles 10 contained in the positive electrode composite material. If the tungsten content is less than 1.0% by weight, it is difficult to construct lithium ion conduction paths, and the effect of reducing the initial reaction resistance becomes small. Also, since tungsten does not directly contribute to the battery reaction, if the tungsten content exceeds 2.0% by weight, the battery capacity decreases or the rate of increase in battery resistance increases, leading to deterioration.

[0024] The inorganic filler particles 13 can be made of ceramics. For example, in addition to Al2O3 particles, SiO2 particles and the like can be used as ceramics. From the viewpoint of sealing the recesses 16, it is preferable that the average particle size of the inorganic filler particles is 0.01 μm or more and 1.0 μm or less. If the average particle size is less than 0.01 μm, the effect of sealing the recesses 16 cannot be sufficiently obtained. Also, if the average particle size exceeds 1.0 μm, it is too large and the effect of sealing the recesses 16 cannot be sufficiently obtained.

[0025] Furthermore, the content of inorganic filler particles 13 is preferably 0.05% by weight or more and 1.0% by weight or less relative to the total weight of the positive electrode composite material provided on the positive electrode plate. If the content is less than 0.05% by weight, the effect of blocking the recess 16 cannot be sufficiently obtained. Also, since the inorganic filler particles 13 themselves have high resistance, if the content exceeds 1.0% by weight, the battery resistance may increase.

[0026] The negative electrode comprises a negative electrode current collector and a negative electrode composite layer. The negative electrode current collector is, for example, a metal foil such as copper or a copper alloy. The negative electrode composite layer contains a carbon material as the negative electrode active material. Examples of carbon materials include graphene, carbon black, graphite, carbon fibers, and carbon nanotubes. The negative electrode composite layer may further contain a binder, a thickener, etc. The negative electrode material is not limited to those described above, and materials commonly used in lithium-ion secondary batteries can be used.

[0027] The separator can be made of known materials such as microporous resin sheets made of resins such as polyethylene (PE) or polypropylene (PP). The separator is not limited to those mentioned above, and any material commonly used in lithium-ion secondary batteries can be used.

[0028] The non-aqueous electrolyte comprises a solvent and a supporting salt dissolved in the solvent. For example, as the non-aqueous solvent, at least one of organic solvents such as carbonates, ethers, esters, nitriles, and sulfones can be used. Specifically, these include ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC). As the supporting salt, at least one lithium salt such as LiPF6, LiBF4, or LiClO4 can be used. The non-aqueous electrolyte is not limited to those described above, and materials commonly used in lithium-ion secondary batteries can be used.

[0029] [Manufacturing method for lithium-ion secondary batteries] The procedure for manufacturing a lithium-ion secondary battery will be explained with reference to Figure 5. First, cathode particles 10 without inorganic filler particles 13 are prepared (step S1). For example, the cathode particles 10 prepared in step S1 are manufactured as follows: First, a powder is prepared by crushing a cathode active material such as lithium nickel cobalt manganese composite oxide. Then, the crushed powder is mixed with tungstic acid (WO3), and the mixture is heat-treated to cause a reaction. This forms cathode particles 10 with a coating layer 12 formed on the core portion 11. At this time, a small amount of tungstic acid that did not react is mixed in with the cathode particles 10.

[0030] Next, the coating amount C is measured (step S2). The coating amount C can be expressed as the weight of the coating layer 12 per unit area of ​​the core portion 11. The coating amount C can be quantified by classification or the like. For example, the positive electrode particles 10 prepared in step S1 are separated by a centrifuge using the weight difference between the positive electrode active material and tungstic acid. The tungstic acid separated here is unreacted. Then, the weight of the separated tungstic acid is measured. Since the weight of tungstic acid used in the production of the positive electrode particles 10 is known, the weight of the tungstic acid that reacted and formed the coating layer 12 is determined by subtracting the weight of the unreacted tungstic acid from that weight. Then, the weight of lithium tungstic acid (Li2WO4) is determined based on the weight of the reacted tungstic acid and the weight ratio of tungstic acid and lithium tungstic acid per mole. Note that the coating amount C may be measured by other methods.

[0031] Next, it is determined whether the coating amount C is equal to or greater than the specified amount (determination step S3). If it is determined that the coating amount C is equal to or greater than the specified amount (determination step S3: YES), the amount of inorganic filler particles 13 to be added is determined using the correlation between the coating amount C and the resistance increase amount ΔR1, and the correlation between the amount of inorganic filler particles 13 added and the resistance increase amount ΔR2 (step S4).

[0032] Specifically, the predicted resistance increase ΔR1 for the measured coating amount C is determined from the correlation between the coating amount C and the resistance increase ΔR1 after high-temperature storage of the battery, as illustrated in the graph of Figure 2, and from the coating amount C measured in step S2. Furthermore, the amount of inorganic filler particles 13 to be added that corresponds to the same (or equivalent) resistance increase ΔR2 as the identified resistance increase ΔR1 is determined from the correlation between the identified resistance increase ΔR1 and the amount of inorganic filler particles 13 added and the resistance increase ΔR2, as illustrated in Figure 3.

[0033] Then, inorganic filler particles 13, whose amount was specified in step S4, are added to a mixture containing a predetermined amount of positive electrode particles 10, a conductive additive, a binder, etc. (step S5). If it is determined that the coating amount C is less than the specified amount (determination step S3: NO), and after adding inorganic filler particles 13 to a predetermined amount of positive electrode particles 10 (step S5), the mixture is kneaded with a solvent, etc. (step S6). When inorganic filler particles 13 are added to the mixture, filler-coated positive electrode particles 10A are produced.

[0034] This positive electrode slurry is applied to both sides of a long positive electrode current collector (step S7). The slurry is then dried and pressed (step S8). This forms a positive electrode plate. The positive electrode plate is wound with a separator between it and the negative electrode plate. The positive electrode terminal is electrically connected to the positive electrode plate, and the negative electrode terminal is connected to the negative electrode plate. The wound material, along with a non-aqueous electrolyte, is housed in a battery case having positive and negative electrode terminals.

[0035] Thus, the amount of inorganic filler particles 13 added can be determined from the correlation between the coating amount C and the resistance increase ΔR1 after high-temperature storage of the battery, and from the correlation between the amount of inorganic filler particles 13 added and the resistance increase ΔR2. The increase in resistance increase ΔR1 can be offset in advance by the resistance increase ΔR2.

[0036] <Operation and Effects of This Embodiment> The operation and effects of this embodiment will now be described. (1) The inorganic filler particles 13 added to the positive electrode composite can block the core portion 11 exposed due to coating irregularities, thereby suppressing the progression of side reactions with the electrolyte on the surface of the active material. This keeps the battery resistance low and suppresses the decrease in output performance at the end of the lifespan of the non-aqueous electrolyte secondary battery.

[0037] (2) When the amount of coating C of the coating layer 12 is equal to or greater than the specified amount, inorganic filler particles 13 are added to the mixture. Therefore, by adding inorganic filler particles 13 only when the battery resistance due to the amount of coating C is large, the decrease in battery capacity can be suppressed.

[0038] (Example of change) This embodiment can be implemented with the following modifications. This embodiment and the following modifications can be combined with each other to the extent that they do not contradict each other technically.

[0039] In the above embodiment, the amount of inorganic filler particles 13 to be added was determined using the correlation between the coating amount C and the resistance increase ΔR1, and the correlation between the amount of inorganic filler particles 13 added and the resistance increase ΔR2 (step S4). Alternatively, the amount of inorganic filler particles 13 to be added may be kept constant.

[0040] In the above embodiment, the coating layer 12 is composed mainly of a lithium tungstate compound. The coating layer 12 may contain more tungsten than the core portion 11, and may also contain tungsten compounds other than lithium tungstate.

[0041] In the above embodiment, the lithium-ion secondary battery is made of a wound body, but the configuration is not limited to this. Also, although the non-aqueous electrolyte secondary battery is embodied as a lithium-ion secondary battery, other non-aqueous electrolyte secondary batteries such as sodium-ion secondary batteries, in which sodium ions are responsible for electrical conduction, may also be used.

[0042] (Examples) The negative electrode carbon material for lithium-ion batteries will be described in more detail based on the following examples. Note that the negative electrode carbon material for lithium-ion batteries is not limited to the configurations described in the Examples section.

[0043] Lithium-ion secondary batteries of Examples 1 and 2 and Comparative Example 1 were manufactured with the compositions shown in Table 1. In the above embodiments, whether or not to add inorganic filler particles 13 is determined according to the specified amount, so if the coating amount C is appropriate, batteries without inorganic filler particles 13 can also be manufactured. Therefore, in the following, the specified amount of coating amount C was set to a range greater than the coating amount of Example 2 and smaller than that of Example 1 and Comparative Example 1. Example 2 is an example in which inorganic filler particles 13 were not added because the coating amount C was small, and Example 1 is an example in which inorganic filler particles 13 were added because the coating amount C exceeded the specified amount. Comparative Example 1 is an example in which inorganic filler particles 13 were not included despite the coating amount C exceeding the specified amount.

[0044] A positive electrode particle 10 was prepared, having a core portion 11 containing LiNiCoMnO2 as the positive electrode active material and a coating layer 12 made of Li2WO4. In addition, Al2O3 was prepared as inorganic filler particles 13, carbon nanotubes as a conductive material, and PVdF as a binder. Then, a mixture was formed as follows, and a solvent was added to prepare a positive electrode slurry.

[0045] (Example 1) The tungsten content (amount added) in the total positive electrode particles 10 was the same in Examples 1 and 2 and Comparative Example 1. The tungsten content is the ratio of the weight of tungsten contained in all positive electrode particles 10 to the total weight of all positive electrode particles 10 contained in the positive electrode mixture. In addition, the Li2WO4 content relative to the total positive electrode particles 10 was 1.05 times that of Example 2. The Li2WO4 content is the ratio of the weight of Li2WO4 contained in all positive electrode particles 10 to the total weight of all positive electrode particles 10 contained in the positive electrode mixture.

[0046] A cathode slurry of the cathode composite material was prepared by mixing Al2O3 particles with a mixture consisting of cathode particles 10, a conductive material, and a binder. The content of Al2O3 particles was 0.05% by weight relative to the cathode active material.

[0047] (Example 2) The Li2WO4 content in Example 2 was set to "1.00" (times) based on the standards for Example 1 and Comparative Example 1. Inorganic filler particles 13 were not added to the mixture consisting of positive electrode particles 10, conductive material, and binder. The positive electrode slurry was prepared in the same manner as in Example 1.

[0048] (Comparative Example 1) In this case, inorganic filler particles 13 were not added to the mixture consisting of positive electrode particles 10, a conductive material, and a binder. The positive electrode slurry was prepared in the same manner as in Example 1.

[0049] The prepared positive electrode slurry was coated onto aluminum foil, dried, and then pressed to obtain a positive electrode plate. Furthermore, a negative electrode slurry was prepared by mixing graphite, a binder, a thickener, etc., as the negative electrode active material. The prepared slurry was coated onto copper foil, dried, and then pressed to obtain a negative electrode plate. Then, a wound body was prepared by winding the positive electrode plate and the negative electrode plate with a separator in between, and the battery was assembled by sealing the wound body and LiPF6 as a non-aqueous electrolyte in a battery case.

[0050] [Table 1]

[0051] The initial DCIR of lithium-ion secondary batteries in Examples 1 and 2 and Comparative Example 1 was measured. These DCIRs were defined as the cell resistance at a state of charge (SOC) of 30%, a temperature of 25°C, and a measurement time of 10 seconds.

[0052] Furthermore, the lithium-ion secondary batteries of Examples 1 and 2 and Comparative Example 1 were stored for 14 days under conditions of 80% charge and 70°C. Afterward, the DCIR of each lithium-ion secondary battery was measured and recorded as the post-storage DC-IR.

[0053] The initial DC-IR of Example 2 was set to 100%, and the initial DC-IR of Example 1 and Comparative Example 1, as well as the DC-IR after storage of Examples 1, 2, and Comparative Example 1, were evaluated. The initial DC-IR of the battery in Example 1 was slightly reduced to "99.7%" compared to the reference Example 2. Comparative Example 1 showed a similar result. This is thought to be because, compared to Example 2, the amount of coating C on Li2WO4 was larger, allowing conduction paths to be formed by tungsten.

[0054] On the other hand, the DC-IR after storage in Example 2 was "114.0%" of the initial DC-IR in Example 2, and the resistance increase was "14.0%". The DC-IR after storage in Example 1 was "113.8%" of the initial DC-IR in Example 2, and the overall resistance increase of the battery was "14.1%", which was equivalent to Example 2.

[0055] In Example 1, the amount of Li2WO4 coating C was 1.05 times greater than in Example 2, and it was predicted that the resistance increase would be worse than in Example 2 due to the excessive coating. However, by adding inorganic filler particles 13 during slurry mixing, the resistance increase was suppressed, resulting in a resistance increase equivalent to that of Example 2.

[0056] On the other hand, the DC-IR of Comparative Example 1 after storage was "117.0%" of the initial DC-IR of Example 2, and the increase in the overall resistance of the battery was "17.3%". This is because the amount of Li2WO4 coating C was 1.05 times greater than that of Example 2, resulting in excessive coating. Furthermore, it is thought that Comparative Example 1 could not reduce the increase in resistance because the inorganic filler particles 13 were not added, and therefore the unevenness of the coating layer 12 was not covered. [Explanation of Symbols]

[0057] 10…Positive electrode particle 11…Core section 12…Court layer 13… Inorganic filler particles

Claims

1. A method for manufacturing a positive electrode for a non-aqueous electrolyte battery, A step of preparing positive electrode particles having a core portion mainly composed of a positive electrode active material and a coating layer containing a lithium tungstate compound and covering the core portion, A step of measuring the amount of the coating layer, which is the amount of the coating layer per unit area of ​​the core portion, A method for producing a positive electrode for a non-aqueous electrolyte battery, comprising the step of kneading a mixture containing the positive electrode particles and inorganic filler particles according to the amount of coating.

2. The system further includes a determination step of determining whether the amount of coating is equal to or greater than a specified amount, A method for producing a positive electrode for a non-aqueous electrolyte battery according to claim 1, wherein in the step of kneading the mixture, the inorganic filler particles are added to the mixture if it is determined in the determination step that the amount of coating is equal to or greater than the specified amount.

3. In the step of kneading the mixture, Al is used as the inorganic filler particle. ２ O ３ A method for producing a positive electrode for a non-aqueous electrolyte battery according to claim 1, comprising adding particles.

4. The correlation between the amount of coating and the increase in resistance after high-temperature storage of the non-aqueous electrolyte battery, and the measured amount of coating, are used to determine the predicted increase in resistance relative to the measured amount of coating. From the correlation between the identified resistance increase and the amount of inorganic filler particles added and the resistance increase, the amount of inorganic filler particles added corresponding to the identified resistance increase is determined. A method for producing a positive electrode for a non-aqueous electrolyte battery according to any one of claims 1 to 3, comprising including the specified amount of inorganic filler particles in the mixture.

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