Manufacturing method for positive electrode plate for lithium-ion secondary battery, manufacturing method for lithium-ion secondary battery, and manufacturing device for positive electrode plate for lithium-ion secondary battery

Abstract

To accurately identify the amount of oxide that reacts with LiOH on the surface of a positive electrode active material to form a coating of lithium oxide.SOLUTION: The manufacturing method for a positive electrode plate for a lithium-ion secondary battery for estimating the amount of coating CA [g] by oxide that forms a coating of lithium oxide by reacting with LiOH on the positive electrode active material includes an actual specific capacity measuring step (S14) for measuring an actual specific capacity SCa [mAh / g] of a positive electrode composite paste coated on a positive electrode current collector, a standard specific capacity calculation step (S15) for calculating a standard specific capacity SCr [mAh / g] from the composition ratio of the metals composed of the positive electrode active material particles, which do not have a film formed on the surface, and a specific capacity difference calculation step (S16) for calculating a finite difference ΔSC [mAh / g] by comparing the actual specific capacity SCa [mAh / g] with the standard specific capacity SCr [mAh / g]. The finite difference ΔSC [mAh / g] is compared with a threshold value Th to determine whether the positive electrode plate is good or bad (S17).SELECTED DRAWING: Figure 8

Description

[Technical field]

[0001] The present invention relates to a method for manufacturing a positive plate for a lithium ion secondary battery, a method for manufacturing a lithium ion secondary battery, and an apparatus for manufacturing a positive plate for a lithium ion secondary battery, and more particularly to a method for manufacturing a positive plate for a lithium ion secondary battery, which are capable of estimating the amount of lithium oxide coating the surface of a positive electrode active material, a method for manufacturing a lithium ion secondary battery, and an apparatus for manufacturing a positive plate for a lithium ion secondary battery. [Background technology]

[0002] Lithium ion secondary batteries are charged by inserting lithium ions of the positive electrode active material into the negative electrode, and discharged by inserting the lithium ions removed from the negative electrode back into the positive electrode. That is, during the charge and discharge reaction of lithium ion secondary batteries, lithium ions move between the positive electrode active material and the electrolyte. Therefore, in order to aim for high output of lithium ion secondary batteries, it is desirable to have a low reaction resistance between the positive electrode active material and the electrolyte. For this reason, when the positive electrode active material is mixed with other binders, conductive materials, etc. to form a positive electrode composite layer, an oxide that reacts with LiOH to form a lithium oxide, for example, an oxide of a different element such as WO3, may be added in advance to improve the conductivity of the positive electrode active material. In the case of WO3, a coating is formed on the surface of the positive electrode active material as a lithium compound such as Li2WO4. At this time, there are some that do not react with LiOH and do not form a coating, and are unevenly distributed on the surface of the positive electrode active material in the state of an oxide as added, such as WO3.

[0003] The reaction resistance of the positive electrode varies depending on the amount of Li2WO4 coating formed on the surface of the positive electrode active material, and the greater the amount of Li2WO4 coating, the smaller the reaction resistance. On the other hand, oxides such as WO3 that are added without a coating and are unevenly distributed on the surface of the positive electrode active material do not contribute much to reducing the reaction resistance. For this reason, in order to accurately evaluate battery performance, it is necessary to accurately grasp the amount of Li2WO4 coating, rather than simply the amount of WO3 added.

[0004] On the other hand, in ICP analysis (optical emission spectroscopy) and other methods, it is difficult to quantitatively separate with high precision the amount of W as the amount of Li2WO4 coating formed on the surface of the positive electrode active material and the amount of unevenly distributed WO3. This is because ICP analysis measures W by micronizing the sample, so it is not possible to tell whether the amount is Li2WO4 coating formed on the surface of the positive electrode active material or unevenly distributed WO3.

[0005] Furthermore, even if the amount of Li2WO4 formed on the surface of the positive electrode active material at the time of delivery of all materials can be accurately measured in advance, there are problems such as the following. The positive electrode active material is mixed with other auxiliary materials to form the positive electrode composite layer. In this process, there is WO3 that is unevenly distributed on the surface of the positive electrode active material in the form of an oxide such as WO3, without forming a coating. When the positive electrode composite paste is prepared, it may react with LiOH during the kneading process, forming a coating on the surface of the positive electrode active material as a lithium compound such as Li2WO4. For these reasons, the amount of Li2WO4 coating formed on the surface of the positive electrode active material in the positive electrode composite layer changes.

[0006] Here, there is an example in which an oxide or the like is coated on a positive electrode active material, as in the invention described in Patent Document 1. The invention described in Patent Document 2 also discloses an invention in which a positive electrode active material is coated with a metal and / or an intermetallic compound obtained by combining a plurality of these metals, and / or an oxide.

[0007] According to these inventions, a coating can be formed on the surface of the positive electrode active material, thereby reducing the reaction resistance. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] JP 2019-21610 A [Patent Document 2] Japanese Patent Application Publication No. 11-16566 Summary of the Invention [Problem to be solved by the invention]

[0009] In the example of Patent Document 1, the method of quantitatively measuring the amount of coating with high accuracy is specified by local quantitative measurement using energy dispersive X-ray spectroscopy or the amount of the positive electrode active material. However, in this case, the added oxide does not become a lithium compound even if it is added, and does not contribute to reducing the reaction resistance. Such an amount cannot be determined by energy dispersive X-ray analysis or the amount of the positive electrode active material. As a result, it was not possible to accurately measure only the oxide coated on the surface of the positive electrode active material.

[0010] Moreover, the invention described in Patent Document 2 describes only the blending amount, and does not describe a method for measuring only the coating amount. For this reason, the conventional technology has a problem in that it is not possible to accurately determine the amount of only the oxide that reacts with LiOH on the surface of the positive electrode active material to form a lithium oxide film.

[0011] The manufacturing method for a positive electrode plate for a lithium ion secondary battery, the manufacturing method for a lithium ion secondary battery, and the manufacturing apparatus for a positive electrode plate for a lithium ion secondary battery of the present invention aim to accurately identify the amount of only the oxide that reacts with LiOH on the surface of the positive electrode active material to form a lithium oxide coating. [Means for solving the problem]

[0012] In order to solve the above problems, the method for manufacturing a positive electrode plate for a lithium ion secondary battery of the present invention estimates an amount of a coating CA [g] of an oxide that reacts with LiOH on the surface of a particle of a positive electrode active material of a lithium ion secondary battery to form a lithium oxide coating, the method comprising the steps of: a positive electrode kneading step of kneading the particles of the positive electrode active material as a raw material with a sub-material to manufacture a positive electrode mixture paste; a positive electrode coating step of coating a positive electrode current collector with the positive electrode mixture paste manufactured in the positive electrode kneading step; and the actual specific capacity measuring step of measuring the actual specific capacity SCa [mAh / g] of the positive electrode composite paste applied to a body; a reference specific capacity calculating step of calculating a reference specific capacity SCr [mAh / g] from a composition ratio of metals constituting particles of the raw material positive electrode active material on which a coating is not formed; and a specific capacity difference calculating step of comparing the actual specific capacity SCa [mAh / g] measured in the actual specific capacity measuring step with the reference specific capacity SCr [mAh / g] calculated in the reference specific capacity calculating step to determine a difference ΔSC [mAh / g].

[0013] The method may further include a coating amount estimating step of estimating the coating amount CA [g] from the specific capacity difference ΔSC [mAh / g] calculated in the specific capacity difference calculating step. In this case, the positive electrode active material is mainly composed of Ni, Mn, and Co, and in the standard specific capacity calculation step, the standard specific capacity SCr [mAh / g] is calculated by testing based on the metal composition ratios consisting of the Co ratio, Ni / Mn ratio, and Li / Me ratio when the sum of the masses of Ni, Mn, and Co is defined as Me, and the standard specific capacity SCr [Ah / g] can be calculated by determining the coefficients A, B, and C in the following formula (1) and SCr = (A × Co ratio) + (B × Ni / Mn ratio) + (C × Li / Me ratio) + constant term... formula (1).

[0014] The method may further include a quality determination step of comparing the difference ΔSC [mAh / g] calculated in the specific capacity difference calculation step with a preset threshold value Th to determine the quality of the lithium ion secondary battery.

[0015] If the lithium ion secondary battery is determined to be defective in the quality determination step, the coating amount of the positive electrode composite paste in the positive electrode coating step can be increased or decreased according to the calculated difference ΔSC [mAh / g] in the specific capacity.

[0016] In addition, if the lithium ion secondary battery is determined to be defective in the quality determination step, the amount of additive to the electrolyte can be increased or decreased according to the calculated difference in specific capacity ΔSC [mAh / g].

[0017] This can be suitably carried out when the oxide that reacts with LiOH to form a lithium oxide film is WO3. The method can also be suitably carried out when the oxide that reacts with LiOH to form a lithium oxide film is any one of ZrO2, H3PO4, and TiO2.

[0018] Moreover, a method for producing a lithium ion secondary battery of the present invention can include the method for producing a positive electrode plate of the lithium ion secondary battery described above. The manufacturing apparatus for a positive electrode plate of a lithium ion secondary battery of the present invention is an estimation apparatus that estimates an amount CA [g] of a coating of lithium oxide formed by reacting with LiOH on the surface of a particle of a positive electrode active material of a lithium ion secondary battery, the estimation apparatus including a control device having a computer, and a specific capacity measurement means for measuring a specific capacity SCa [mAh / g] of a positive electrode composite paste produced by kneading particles of the positive electrode active material as a raw material with a sub-material, and coating the positive electrode composite paste on a positive electrode current collector; The present invention is characterized in that it functions as a reference specific capacity calculation means for calculating a reference specific capacity SCr [Ah / g] from the composition ratio of the metals constituting particles on which a coating of a specific substance is not formed, a specific capacity difference calculation means for comparing the actual specific capacity SCa [Ah / g] measured by the actual specific capacity measurement means with the reference specific capacity SCr [Ah / g] calculated by the reference specific capacity calculation means to obtain a difference ΔSC [Ah / g], and a coating amount estimation means for estimating the coating amount CA [g] from the specific capacity difference ΔSC [Ah / g] obtained by the specific capacity difference calculation means. Effect of the Invention

[0019] The method for manufacturing a positive electrode plate for a lithium ion secondary battery, the method for manufacturing a lithium ion secondary battery, and the apparatus for manufacturing a positive electrode plate for a lithium ion secondary battery of the present invention have the advantage of being able to accurately identify the amount of only the oxide that reacts with LiOH on the surface of the positive electrode active material to form a lithium oxide coating. [Brief description of the drawings]

[0020] [Figure 1] 1 is a graph showing the relationship between the reference specific capacity SCr [mAh / g] and the actual specific capacity SCa [mAh / g]. [Diagram 2] 1 is a graph showing the relationship between the difference ΔSC [mAh / g] and the coating amount CA [g] of Li2WO4. [Diagram 3] 1 is a graph showing the relationship between the amount of Li2WO4 coating [g] and the reaction resistance Rr [mΩ] in the positive electrode. [Figure 4] 1 is a perspective view showing the outline of the external configuration of a lithium-ion secondary battery according to an embodiment of the present invention; [Diagram 5] FIG. 2 is a schematic diagram showing the configuration of a wound electrode body. [Figure 6] FIG. 1 is a block diagram of a film amount estimation device for a positive electrode active material of a lithium ion secondary battery. [Figure 7] 2 is a flowchart showing an example of a method for manufacturing the lithium ion secondary battery according to the present embodiment. [Figure 8] 4 is a flowchart showing a method for estimating the coating amount of a positive electrode active material according to the present embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] A method for manufacturing a positive electrode plate of a lithium ion secondary battery and an estimation device according to the present invention will be described with reference to one embodiment of the method for manufacturing a lithium ion secondary battery 1 with reference to FIGS. <Problems with the Background Technology> First, the principle of the invention according to this embodiment will be described. As explained in the background art, in order to improve the conductivity of the positive electrode active material in order to achieve high output, a coating may be formed on the surface of the particles of the positive electrode active material of a lithium ion secondary battery. For this reason, an oxide that reacts with LiOH to form a lithium oxide, for example, an oxide of a different element such as WO3, may be added. In the case of WO3, a coating is formed on the surface of the positive electrode active material as a lithium compound such as Li2WO4. At this time, there are also oxides that are unevenly distributed on the surface of the positive electrode active material in the state of oxides that are added as they are, such as WO3, without forming a coating. In the example of Patent Document 1, the local quantitative amount is specified by energy dispersive X-ray analysis or the like, or the amount of the positive electrode active material charged, etc., regarding a method for quantitatively measuring the amount of coating with high precision. However, in this case, the oxide that is added does not become a lithium compound even if it is added and remains as it is does not contribute much to reducing the reaction resistance Rr [mΩ]. Such an amount cannot be analyzed by energy dispersive X-ray analysis or the amount charged. As a result, it was not possible to accurately measure only the oxide coated on the surface of the positive electrode active material. For this reason, the conventional technology has a problem in that it is not possible to accurately determine the amount of only the oxide that reacts with LiOH on the surface of the positive electrode active material to form a lithium oxide film.

[0022] <Principle of the Invention of the Present Embodiment> The method for producing the lithium ion secondary battery 1 according to the present embodiment is characterized in that it is possible to accurately determine the amount of only the oxide that reacts with LiOH on the surface of the positive electrode active material to form a lithium oxide film. The principle of this method is described below.

[0023] The inventors made the following hypothesis. First, when a coating is formed on the surface of a particle of a positive electrode active material as a lithium compound such as Li2WO4, the composition ratio of the metals constituting the positive electrode active material changes. In particular, Li decreases compared to other metals. This causes a change in the specific capacity [mAh / g] of the positive electrode active material. Therefore, the specific capacity [mAh / g] of the positive electrode active material used in the lithium ion secondary battery 1 to be manufactured is measured and obtained in advance, with the specific capacity [mAh / g] of the positive electrode active material, which is the raw material before the coating is formed, being taken as the reference specific capacity SCr [mAh / g].

[0024] On the other hand, the raw material positive electrode active material particles are mixed with the auxiliary material to produce a positive electrode composite paste, which is then applied to the positive electrode current collector.Then, the actual specific capacity SCa [mAh / g] of the positive electrode composite paste applied to the positive electrode current collector is actually measured.

[0025] Then, the difference ΔSC [mAh / g] between the actual specific capacity SCa [mAh / g] and the reference specific capacity SCr [mAh / g] is calculated. It was predicted that the magnitude of this difference ΔSC [mAh / g] correlates with the amount of coating [g] on the surface of the positive electrode active material as a lithium compound. According to this hypothesis, the inventors actually verified that the magnitude of this difference ΔSC [mAh / g] correlates with the amount of coating [g] on the surface of the positive electrode active material as a lithium compound, and demonstrated that the hypothesis is correct.

[0026] <Standard specific capacity SCr [mAh / g] and actual specific capacity SCa [mAh / g]> FIG. 1 is a graph showing the relationship between the reference specific capacity SCr [mAh / g] and the actual specific capacity SCa [mAh / g]. The horizontal axis is the reference specific capacity SCr [mAh / g], and the vertical axis is the actual specific capacity SCa [mAh / g]. The straight line graph L1 is a graph of y=x where the reference specific capacity SCr [mAh / g] = the actual specific capacity SCa [mAh / g]. The circles are plotted points measured under various conditions. For example, the intersection of the plotted point P1 among these plotted points with a straight line extending vertically downward from this point P1 along the y axis is set as point P2. The difference in the y coordinate between this point P1 and point P2 is set as the difference ΔSC [mAh / g].

[0027] Here, the points on the graph L1 in Figure 1 are not coated because the reference specific capacity SCr [mAh / g] = the actual specific capacity SCa [mAh / g]. As can be seen from Figure 1, the plot points with a large amount of Li2WO4 coating are points shifted upward from the graph L1. On the other hand, the plot points with a small amount of Li2WO4 coating are located close to the graph L1.

[0028] That is, when the amount of Li2WO4 coating CA [g] is small, the difference between the reference specific capacity SCr [mAh / g] and the actual specific capacity SCa [mAh / g] is small. However, when the amount of Li2WO4 coating CA [g] is large, the actual specific capacity SCa [mAh / g] becomes larger than the reference specific capacity SCr [mAh / g]. In other words, the difference ΔSC [mAh / g] becomes large.

[0029] <Difference ΔSC [mAh / g] and Li2WO4 coating amount CA [g]> Here, FIG. 2 is a graph showing the relationship between the difference ΔSC [mAh / g] and the amount of coating CA [g] of Li2WO4. The horizontal axis shows the difference ΔSC [mAh / g], and the vertical axis shows the amount of coating CA [g] of Li2WO4. The inventors obtained "difference ΔSC = actual specific capacity SCa - reference specific capacity SCr" and estimated the amount of coating CA [g] of Li2WO4 from this difference ΔSC [mAh / g]. From an experiment, it was confirmed that there is a clear positive correlation between the difference ΔSC [mAh / g] and the amount of coating CA [g] of Li2WO4 as shown in graph L2 in FIG. 2. In other words, the amount of coating CA [g] of Li2WO4 can be estimated by obtaining the difference ΔSC [mAh / g].

[0030] <Adjustment of reaction resistance Rr [mΩ] of the positive electrode in this embodiment> Figure 3 is a graph showing the relationship between the amount of Li2WO4 coating [g] and the reaction resistance Rr [mΩ] in the positive electrode. The horizontal axis shows the amount of Li2WO4 coating [g], and the vertical axis shows the reaction resistance Rr [mΩ] in the positive electrode.

[0031] In Figure 3, the measured values ​​indicated by "□" are the basis weight [g / m 2The measured value when the positive electrode composite paste weight [g / m2] is relatively small is shown in graph L3. The measured value indicated by "△" is the weight of the positive electrode composite paste per unit area [g / m2]. 2 The measured value when the positive electrode composite paste was in the medium range is shown in graph L4. The measured value indicated by "◯" is the basis weight [g / m 2 ] is a measured value when it is relatively large, and the straight line obtained from this is graph L5.

[0032] As shown in Figure 3, in all of the graphs L3, L4, and L5, the graphs slope downward to the right, and it can be seen that as the coating weight [g] of Li2WO4 increases, the reaction resistance Rr [mΩ] in the positive electrode decreases. Also, as shown in graph L5, the coating weight [g / m 2 ] increases, the reaction resistance Rr [mΩ] in the positive electrode decreases. On the other hand, as shown in graph L3, the basis weight [g / m 2 ] becomes smaller, the reaction resistance Rr [mΩ] in the positive electrode increases. Therefore, if the coating weight [g] of Li2WO4 can be estimated, the coating weight [g / m 2 By adjusting the reaction resistance Rr [mΩ] required in the positive electrode, it is possible to obtain the required performance.

[0033] For example, if the Li2WO4 coating amount CA [g] is estimated to be Ca1 [g] from the difference ΔSC [mAh / g], the coating amount [g / m 2 ] is the relatively large basis weight [g / m ] shown in graph L3. 2 ] or more, the reaction resistance Rr [mΩ] can be set as the required performance. On the other hand, if the Li2WO4 coating amount CA [g] is estimated to be Ca2 [g] from the difference ΔSC [mAh / g], the coating weight [g / m 2 ] is the medium basis weight [g / m2] shown in graph L2. 2 ] or more, the reaction resistance Rr [mΩ] can be set as the required performance.

[0034] As explained above, the reaction resistance Rr [mΩ] of the positive electrode is determined by the coating weight [g / m 2However, if the Li2WO4 coating weight CA [g] is too low, the coating weight [g / m 2 ] adjustments alone may not be enough to achieve the desired results.

[0035] (Configuration of this embodiment) Hereinafter, the present embodiment, which is an example of the configuration of the present invention, will be described in detail. <Configuration of lithium-ion secondary battery 1> 4 is a perspective view showing the outline of the external configuration of the lithium ion secondary battery 1 of this embodiment. First, the configuration of the lithium ion secondary battery 1 of this embodiment, which is an example of the present invention, will be described.

[0036] As shown in FIG. 4, the lithium ion secondary battery 1 is configured as a cell battery. The lithium ion secondary battery 1 includes a battery case 11 in the shape of a plate-like rectangular parallelepiped having an opening on the upper side. An electrode body 12 is accommodated inside the battery case 11. A nonaqueous electrolyte 13 is filled into the battery case 11 through a liquid inlet. The battery case 11 is made of a metal such as an aluminum alloy, and forms a battery container sealed by a lid. The lithium ion secondary battery 1 also includes a positive electrode external terminal 14 and a negative electrode external terminal 15 used for charging and discharging power. The positive electrode external terminal 14 is electrically connected to a positive electrode current collector terminal 16 inside the battery case 11 via the lid. The negative electrode external terminal 15 is electrically connected to a negative electrode current collector terminal 17 inside the battery case 11 via the lid. The positive electrode current collector terminal 16 is electrically connected to a positive electrode current collector part 33 (see FIG. 5) of the electrode body 12. Moreover, the negative electrode current collector terminal 17 is electrically connected to the negative electrode current collector portion 23 of the electrode body 12 (see FIG. 5).

[0037] <Electrode body 12> FIG. 5 is a schematic diagram showing the configuration of the wound electrode body 12. The electrode body 12 is formed by stacking a large number of negative electrode plates 2 and positive electrode plates 3 with separators 4 arranged between them. The stacked negative electrode plates 2, positive electrode plates 3, and separators 4 are wound to form a flat shape. The negative electrode plates 2 have a negative electrode composite layer 22 formed on a negative electrode current collector 21 made of copper foil as a base material. A negative electrode current collector 23 is provided on one end side of a width direction W (winding axis direction) perpendicular to the winding direction (winding direction L). The negative electrode current collector 23 is configured such that the negative electrode composite layer 22 is not formed and the negative electrode current collector 21 is exposed.

[0038] In the positive electrode plate 3, a positive electrode composite layer 32 is formed on a positive electrode collector 31 made of aluminum foil as a base material. As shown in Fig. 5, a positive electrode collector 33 is provided on the other end side (opposite to the negative electrode collector 23) in a width direction W (winding axis direction) perpendicular to the winding direction (winding direction L) of the positive electrode collector 31. The positive electrode collector 33 does not have the positive electrode composite layer 32 formed thereon, and the metal of the positive electrode collector 31 is exposed.

[0039] <Layer structure of electrode body 12> As shown in FIG. 5, the basic configuration of an electrode assembly 12 of a lithium ion secondary battery 1 includes a negative electrode plate 2, a positive electrode plate 3, and a separator 4.

[0040] The negative electrode plate 2 includes a negative electrode mixture layer 22 on both sides of a negative electrode current collector 21 serving as a negative electrode base material. One end of the negative electrode current collector 21 serves as a negative electrode current collector 23 where the metal is exposed. The positive electrode plate 3 includes a positive electrode mixture layer 32 on both sides of a positive electrode current collector 31 serving as a positive electrode base material. The other end of the positive electrode current collector 31 forms a positive electrode current collecting portion 33 where the metal is exposed.

[0041] The negative electrode plate 2 and the positive electrode plate 3 are stacked with a separator 4 interposed therebetween to form a laminate. As shown in Fig. 5, this laminate is wound in the longitudinal direction around the winding axis to form a wound-type electrode body 12 that is shaped into a flat shape as shown in Fig. 4.

[0042] <Nonaqueous electrolyte 13> The non-aqueous electrolyte 13 of the lithium ion secondary battery 1 of this embodiment shown in FIG. 4 is a composition in which a lithium salt is dissolved in an organic solvent. As the lithium salt, LiClO4, LiPF6, LiAsF6, LiBF4, LiSO3CF3, etc. can be used. As the organic solvent, cyclic carbonates such as ethylene carbonate, propylene carbonate, butylene carbonate, and trifluoropropylene carbonate, chain carbonates such as diethyl carbonate, dimethyl carbonate, ethyl methyl carbonate, and dipropyl carbonate, ether compounds such as tetrahydrofuran, 2-methyltetrahydrofuran, and dimethoxyethane, sulfur compounds such as ethyl methyl sulfone and butane sultone, and phosphorus compounds such as triethyl phosphate and trioctyl phosphate can be used. As the non-aqueous electrolyte 13, one or more of these can be mixed and used. The composition of the non-aqueous electrolyte 13 is not limited to this.

[0043] <Components of electrode body 12> Next, the negative electrode plate 2, the positive electrode plate 3, and the separator 4, which are the components that make up the electrode assembly 12, will be described.

[0044] <Negative electrode plate 2> As shown in Fig. 5, negative electrode mixture layers 22 are formed on both sides of negative electrode current collector 21, which is a negative electrode base material, to form negative electrode plate 2. In a source process (Fig. 7: S1), negative electrode mixture layer 22 is formed by applying a negative electrode mixture paste to negative electrode current collector 21. Thereafter, negative electrode plate 2 is completed through a drying process, a pressing process, and a cutting process.

[0045] <Negative electrode current collector 21> In this embodiment, the negative electrode current collector 21 is made of Cu foil. The negative electrode current collector 21 serves as a base for the aggregate of the negative electrode mixture layer 22, and also functions as a current collecting member that collects electricity from the negative electrode mixture layer 22. One end of the negative electrode current collector 21 serves as a negative electrode current collecting part 23 where the negative electrode mixture layer 22 is not formed and the metal surface is exposed. In other words, the negative electrode active material particles are electrically connected to the negative electrode external terminal 15 via the negative electrode current collector 21, the negative electrode current collecting part 23, and the negative electrode current collecting terminal 17.

[0046] <Negative electrode composite layer 22> In this embodiment, the negative electrode active material is a powdered carbon material made of graphite or the like having a layered structure, and lithium ions Li + It is a material that can absorb and release energy.

[0047] <Positive electrode plate 3> As shown in Fig. 5, the positive electrode plate 3 is composed of a positive electrode current collector 31, which is a positive electrode base material, and a positive electrode composite layer 32 applied thereto. The positive electrode composite layer 32 is formed by applying a positive electrode composite paste to the positive electrode current collector 31 in a source process (Fig. 7: S1). The positive electrode plate 3 is then completed through a drying process, a pressing process, and a cutting process. The method of manufacturing the positive electrode plate 3 of this embodiment is performed during the manufacturing process of this positive electrode plate 3, and will be described in detail later.

[0048] <Positive electrode current collector 31> A positive electrode mixture layer 32 is formed on both sides of a positive electrode current collector 31, which is a positive electrode base material, to form a positive electrode plate 3. In this embodiment, the positive electrode current collector 31 is made of an Al foil. The positive electrode current collector 31 serves as a base for the aggregate of the positive electrode mixture layer 32, and also functions as a current collecting member that collects electricity from the positive electrode mixture layer 32.

[0049] First, the positive electrode base material constituting the positive electrode current collector 31 is exemplified as an Al foil, but may be made of a conductive material made of a metal having good conductivity. As a material having good conductivity, for example, in addition to Al foil, a material containing an Al alloy may be used. The configuration of the positive electrode current collector 31 is not limited to this.

[0050] <Positive electrode mixture layer 32> Positive electrode mixture layer 32 is formed by applying a positive electrode mixture paste to positive electrode current collector 31 and drying it. Positive electrode mixture layer 32 contains additives such as a conductive assistant, a binder, and a dispersant in addition to positive electrode active material particles.

[0051] <Composition of positive electrode active material> The positive electrode active material particles contain a lithium transition metal oxide having a layered crystal structure. The lithium transition metal oxide contains one or more predetermined transition metal elements in addition to Li. The transition metal element contained in the lithium transition metal oxide is preferably at least one of Ni, Co, and Mn. The positive electrode active material of this embodiment is exemplified by a ternary system called NCM having a lithium transition metal oxide containing all of Ni, Co, and Mn.

[0052] The positive electrode active material of the present embodiment is not limited to a lithium transition metal oxide containing all of Ni, Co, and Mn, and may also be a composition containing, for example, Al in addition to these.

[0053] The positive electrode active material of the present invention can be implemented as long as it is a positive electrode active material whose specific capacity changes depending on the Li / Me ratio, which is the weight ratio of Li to the total metal when Me is the total amount of metal. For example, the present invention can be implemented even if the positive electrode active material is LiMnO4, LiFePO4, etc.

[0054] <Composition ratio of positive electrode active material> In this embodiment, the composition of the positive electrode active material is specified by a composition ratio. The composition ratio of the positive electrode active material (NCM) in this embodiment is specified by a "Co / Me ratio", a "Ni / Mn ratio", and a "Li / Me ratio" where "Me" is the sum of Ni, Co, and Mn.

[0055] "Co ratio" is the mass ratio of Ni in the entire metal. "Ni / Mn ratio" is the mass ratio of Ni to Mn. "Li / Me ratio (Me:total of Ni, Co, and Mn)" is the mass ratio of Li to Me:total of Ni, Co, and Mn.

[0056] <Additional elements> In addition to transition metal elements (i.e., Ni, Co, and Mn), the positive electrode active material particles may further contain one or more additional elements. As the additional elements, the positive electrode active material particles can include any element belonging to Group 1 (alkali metals such as Na), Group 2 (alkaline earth metals such as Mg and Ca), Group 4 (transition metals such as Ti and Zr), Group 6 (transition metals such as Cr and W), Group 8 (transition metals such as Fe), Group 13 (B which is a metalloid element or a metal such as Al), and Group 17 (halogens such as F) of the periodic table.

[0057] In addition, when an element other than Ni, Co, and Mn, for example, Al, is additionally present in the Me layer, the composition ratio is specified after fixing the composition of the element. For example, when Al is added to the ternary system of NCM in the positive electrode active material, Li 1.1 (Ni 0.5 Co 0.2 Mn 0.3 Al 0.1 )O2 has the composition, the "Li / Me ratio" is 1.1 / 1.0, the "Co / Me ratio" is 0.2 / 1.0, and the "Ni / Mn ratio" is 0.5 / 0.3.

[0058] <Oxide that reacts with LiOH to form a lithium oxide film> It is preferable to add an oxide that reacts with LiOH to form a lithium oxide film. Specifically, in addition to WO3, any of ZrO2, H3PO4, and TiO2 is preferable. In the case of ZrO2, the reaction is ZrO2 + LiOH → Li2ZrO3. In the case of H3PO4, the reaction is H3PO4 + LiOH → Li3PO4. In the case of TiO2, the reaction is TiO2 + LiOH → Li2TiO4.

[0059] In this embodiment, by adding WO3, a film of Li2WO4 is formed by the reaction WO3 + 2LiOH → Li2WO4 + H2O. That is, when WO3 is added, a film of Li2WO4 is formed, thereby reducing the mass ratio of Li in the particles of the positive electrode active material.

[0060] <Areal density [g / m 2 > Weight [g / m 2 ] is the area per unit [m 2 In this embodiment, this refers to the weight [g] of the positive electrode active material particles coated on the aluminum foil of the positive electrode current collector 31. 2 The weight per unit area [g / m 2 ] can be adjusted by the density of the positive electrode active material in the positive electrode composite paste, the discharge amount [g / s], the conveying speed [m / s] of the positive electrode current collector 31, etc. 2 ] is large, the positive electrode reaction resistance Rr [mΩ] will be small.

[0061] <Separator 4> The separator 4 is a highly insulating nonwoven fabric made of polypropylene or the like, which is a porous resin for holding the nonaqueous electrolyte 13 between the negative electrode plate 2 and the positive electrode plate 3. As the separator 4, a porous polymer membrane such as a porous polyethylene membrane, a porous polyolefin membrane, and a porous polyvinyl chloride membrane, or a lithium ion or ion conductive polymer electrolyte membrane can be used alone or in combination.

[0062] <Manufacturing apparatus 50 for positive electrode plate 3 of lithium ion secondary battery 1> 6 is a block diagram of an apparatus 50 for manufacturing a positive plate for a lithium-ion secondary battery 1 that measures the specific capacity [mAh / g] of the lithium-ion secondary battery 1 and judges the quality of the positive plate 3 of the lithium-ion secondary battery 1. The apparatus 50 for manufacturing a positive plate includes a measurement circuit and a coating amount estimation device 70.

[0063] <Measurement circuit> 6, a measurement circuit for measuring the specific capacity [mAh / g] of a lithium-ion secondary battery 1 includes the lithium-ion secondary battery 1 and a measurement charge / discharge device 60 for supplying a direct current and an alternating current between the terminals of the lithium-ion secondary battery 1. The measurement circuit also includes a voltage meter 61 for measuring the voltage between the terminals of the lithium-ion secondary battery 1, and a current meter 62 for measuring the current flowing between the measurement charge / discharge device 60 and the lithium-ion secondary battery 1.

[0064] <Measurement charging / discharging device 60> The charge-discharge device 60 for measurement can charge the lithium-ion secondary battery 1 with a direct current of a predetermined current amount and can discharge a direct current of a predetermined current amount from the lithium-ion secondary battery 1. That is, the charge-discharge device 60 for measurement can estimate and adjust the SOC [%] of the lithium-ion secondary battery 1 from the measured current [A] and voltage [V].

[0065] Then, the charge-discharge device 60 for measurement can supply the current for measurement of the specific capacity [mAh / g] to the lithium-ion secondary battery 1 until the lithium-ion secondary battery 1 is fully charged at SOC 100 [%] while adjusting the SOC [%]. Also, while adjusting the SOC [%], the lithium-ion secondary battery 1 can be fully discharged until the SOC becomes 0 [%]. And the battery capacity [Ah] of the lithium-ion secondary battery 1 can be measured. From the measured battery capacity [Ah], the specific capacity [mAh / g] can be measured.

[0066] A temperature measuring device 63 for measuring the temperature of the battery is attached to the lithium-ion secondary battery 1. The temperature measuring device 63 outputs a temperature signal corresponding to the measured temperature of the lithium-ion secondary battery 1 to the film amount estimating device 70. Although not described in detail here, necessary temperature correction and the like can be performed.

[0067] <Film amount estimating device 70> The film amount estimating device 70 estimates the film amount of the lithium-ion secondary battery 1. The procedure for estimating the film amount of the lithium-ion secondary battery 1 will be described in detail later with reference to the flowchart.

[0068] The film amount estimating device 70 includes a processing unit 80 and a storage unit 90. <Processing unit 80> The processing unit 80 is configured to include a computer equipped with a CPU, a ROM, and a RAM. The processing unit 80 controls the entire film amount estimating device 70 of the lithium-ion secondary battery 1. Also, the processing unit 80 exhibits the following functions according to the program stored in the storage unit 90.

[0069] <SOC adjustment unit 81> The SOC adjustment unit 81 estimates the SOC [%] of the lithium ion secondary battery based on the voltage signal input from the voltage measuring device 61 and the current signal input from the current measuring device 62. The SOC adjustment unit 81 also instructs the measurement charging / discharging device 60 to charge and discharge the current, thereby adjusting the lithium ion secondary battery 1 to a predetermined SOC [%].

[0070] <Reference specific capacity calculation unit 82> The reference specific capacity calculation unit 82, as a reference specific capacity calculation means, performs a reference specific capacity calculation step of calculating the reference specific capacity SCr [mAh / g] from the composition ratio of the metals constituting particles of the raw material positive electrode active material that are not coated.

[0071] <Actual capacity measurement unit 83> The actual specific capacity measuring unit 83, as an actual specific capacity measuring means, performs an actual specific capacity measuring step of measuring the actual specific capacity SCa [mAh / g] of the positive electrode composite paste applied to the positive electrode current collector.

[0072] <Coating amount estimation section 84> The coating amount estimation unit 84 performs a coating amount estimation step as a specific capacity difference calculation means. At the same time, the coating amount estimation unit 84 performs a coating amount estimation step of estimating the coating amount CA [g] from the specific capacity difference ΔSC [mAh / g] obtained in the specific capacity difference calculation step as a coating amount estimation means. In this embodiment, the quality determination unit 86 determines the quality of the lithium ion secondary battery 1 only based on the specific capacity difference ΔSC [mAh / g] based on the threshold value Th of the specific capacity difference ΔSC [mAh / g]. This is a determination of the quality of the lithium ion secondary battery 1 based on the coating amount CA [g] in effect. For this reason, the actual coating amount CA [g] is not necessarily required to determine the quality of the lithium ion secondary battery 1. However, since it is an important evaluation in terms of product quality control, a specific coating amount CA [g] can be estimated and displayed as necessary.

[0073] <Threshold setting unit 85> The threshold setting unit 85, as a threshold setting means, determines the coating weight [g / m 2 ] at the time of coating so that the coating weight CA [g] achieves the reaction resistance Rr [mΩ] that is the design target of the lithium ion secondary battery 1. 2 ] is used to determine the threshold value Th of the specific capacity difference ΔSC [mAh / g].

[0074] In detail, the coating weight [g / m2] is set so as to obtain the reaction resistance Rr [mΩ], which is the required performance shown in Figure 3. 2 The Li2WO4 coating amount CA [g] is calculated at the intersection of the graphs L3 to L5 of the graph L3 to L5 in the graph L4 to L5 graph and the line parallel to the horizontal axis showing the reaction resistance Rr [mΩ] that is the required performance. Then, the difference ΔSC [mAh / g] in the specific capacity corresponding to the Li2WO4 coating amount CA [g] calculated in FIG. 2 is calculated.

[0075] <Good / bad judgement unit 86> The quality determining unit 86 performs a quality determining process as a quality determining means. In this embodiment, the quality determining unit 86 determines the quality of the lithium ion secondary battery 1 based only on the specific capacity difference ΔSC [mAh / g] and a threshold value Th. The threshold value Th may indicate only a lower limit for determining whether the battery is a quality product or not, or may indicate a range.

[0076] <Storage section 90> The memory unit 90 is a storage medium such as an HDD or SSD, and stores data such as a reference specific capacity 91 and a judgment threshold value 92, such as the threshold value Th of the difference ΔSC, which are necessary for processing by the processing unit 80, as well as other programs and data required by the processing unit 80.

[0077] <Method of Manufacturing Lithium-Ion Secondary Battery 1> FIG. 7 is a flow chart showing an example of a manufacturing method of the lithium ion secondary battery 1 of this embodiment. The manufacturing method of the lithium ion secondary battery 1 of this embodiment will be briefly described below. In the lithium ion secondary battery 1, which is a cell battery, first, in the source step (S1), the negative electrode plate 2, the positive electrode plate 3, and the separator 4, which are power generating elements, are prepared. After the negative electrode plate 2, the positive electrode plate 3, and the separator 4 are prepared in the source step (S1), the negative electrode plate 2 and the positive electrode plate 3 are stacked and integrated with each other via the separator 4 in the stacking step (S2). The stack thus prepared is wound in the winding step (S3) in the winding direction L as shown in FIG. 4. The stack wound in the winding step (S3) is roughly plate-shaped. Such a wound body is pressed from the thickness direction T by the pressing surfaces of the opposing presses in the wound body pressing step (S4). In the wound body pressing step (S4), the electrode body 12 is pressed until it has a specified thickness [mm] in order to fit the electrode body 12 into the battery case 11 shown in FIG. 1 without any gaps.

[0078] After the thickness of the electrode body 12 is adjusted in the wound body pressing process (S4), an assembly process (S5) is performed. In the assembly process (S5), as shown in FIG. 1, a negative electrode current collector terminal 17 and a positive electrode current collector terminal 16 are attached to the electrode body 12, and further, a negative electrode external terminal 15 and a positive electrode external terminal 14 are attached via a lid. Then, the electrode body 12 is housed in a battery case 11. Then, the lid is welded to the battery case 11 to seal the opening. At this stage, the liquid injection port of the lid is open, so the cell is heated in a cell drying process (S6) to dry the inside of the cell. After the inside of the cell is dried in the cell drying process (S6), nonaqueous electrolyte 13 is injected in a liquid injection / sealing process (S7), and the liquid injection port is sealed and hermetically sealed. This completes the assembly of the lithium ion secondary battery 1.

[0079] Then, in the activation step (S8), an SEI film is formed by initial charging, and in the aging step, the battery is stored at high temperature for a long period of time to eliminate micro-short circuits. Once this activation process (S8) is complete, an inspection process (S9) is carried out to check the battery capacity, internal resistance, self-discharge, OCV, etc., and those that pass are shipped as products.

[0080] <Procedure for manufacturing positive electrode plate> 8 is a flowchart showing the method for producing a positive electrode plate according to this embodiment. The method for producing a positive electrode plate according to this embodiment is carried out as a part of the source step (S1).

[0081] <Material delivery (S11)> First, in the material delivery procedure (S11), in addition to the raw material positive electrode active material, secondary materials such as conductive materials, binders, and additives are prepared. Of these, the metal composition of the particles of the positive electrode active material is specified. The material is specified based on the specifications of the raw material delivery or by actually analyzing the composition. In this embodiment, since the positive electrode active material is NCM, the specified content is determined by the Co ratio, Ni / Mn ratio, and Li / Me ratio (Me: the total of Ni, Co, and Mn).

[0082] <Positive electrode kneading (S12)> In the step of positive electrode kneading (S12), the positive electrode active material is mixed with a conductive material, a binder, an additive, and a solvent and kneaded. By this kneading, a positive electrode mixture paste is generated. By this kneading, a part of WO3 is converted to Li2WO4.

[0083] <Positive electrode coating (S13)> In the step of positive electrode coating (S13), the positive electrode composite paste produced in the step of positive electrode kneading (S12) is applied to the positive electrode current collector 31 by a coating machine (not shown) at a predetermined basis weight [g / m 2 ] according to the difference ΔSC [mAh / g]. 2 ] is applied.

[0084] <Measurement of actual capacity SCa (S14)> In the procedure of measuring the actual specific capacity (S14), after the positive electrode composite paste applied to the positive electrode current collector 31 has dried and solidified, a current is applied and the actual specific capacity SCa [mAh / g] of the positive electrode plate 3 is measured by the coating amount estimation device 70. The actual specific capacity SCa [mAh / g] is calculated by actually measuring the electric capacity [mAh] of the positive electrode plate 3 at SOC 100-0 [%] and dividing the electric capacity [mAh] by the mass [g] of the positive electrode active material.

[0085] <Calculation of standard specific capacity (S15)> In the step of calculating the standard specific capacity (S15), the standard specific capacity SCr [mAh / g] is theoretically calculated by the following formula (1) based on the metal composition determined in the step of supplying materials (S11).

[0086] SCr=A×Co / Me ratio+B×Ni / Mn ratio+C×Li / Me ratio+constant term…(Formula 1) Here, A, B, and C are coefficients obtained through experiments. For example, NCM may be 1.1 (Ni 0.5 , Co 0.2 , Mn 0.3 , Al 0.1 )O2, ignoring Al, the Li / Me ratio is 1.1, the Co / Me ratio is 0.2, and the Ni / Mn ratio is 0.5 / 0.3.

[0087] Based on the above (Equation 1), the reference specific capacity SCr [mAh / g] is calculated. <Calculation of the difference ΔSC between the reference specific capacity SCr and the actual specific capacity SCa (S16)> The difference ΔSC [mAh / g] is calculated by subtracting the reference specific capacity SCr [mAh / g] calculated in the procedure for calculating the reference specific capacity (S15) from the actual specific capacity SCa [mAh / g] measured in the procedure for measuring the actual specific capacity (S14).

[0088] <Is it the specified amount? (S17)> In the step of determining whether the amount is the specified amount (S17), the difference ΔSC [mAh / g] between the reference specific capacity SCr and the actual specific capacity SCa calculated in the step of calculating the difference ΔSC (S16) is multiplied by the basis weight [g / m 2 ] and compares it with the selected threshold value Th to determine whether the difference ΔSC [mAh / g] is a specified amount. The determination of whether it is a specified amount is made by determining only the lower limit based on the threshold value, but it may also be made within a range including an upper limit.

[0089] <Shaping press (S18)> In the shaping press step (S18), if it is determined in the step of determining whether the difference ΔSC [mAh / g] is the specified amount (S17: YES) that the difference ΔSC is the specified amount, the positive electrode plate 3 is shaped by a roller press (not shown) to produce a positive electrode plate 3 that is shaped flat to a specified thickness.

[0090] <Disconnect(S19)> The positive electrode plate 3 shaped in the shaping press step (S18) is cut to a predetermined width and length, and the positive electrode plate 3 is completed.

[0091] <Change in basis weight (S20)> On the other hand, if it is determined in the step of determining whether the amount is the specified amount (S17) that the difference ΔSC [mAh / g] is not the specified amount (S17: NO), the coating amount [g / m 2 ] is changed so that the reaction resistance Rr [mΩ] satisfies the required performance.

[0092] This process is repeated until the difference ΔSC [mAh / g] of the positive electrode plate 3 to be manufactured reaches a specified amount. In this manner, the positive electrode plate 3 of this embodiment is completed. When the other battery elements, the negative electrode plate 2 and the separator 4, are completed, the source step (S1) is completed. Then, the completed negative electrode plate 2, positive electrode plate 3, and separator 4 are stacked in the stacking step (S2).

[0093] (Action of this embodiment) In the method for estimating the amount of coating on the positive electrode active material of the lithium ion secondary battery 1 according to the present embodiment, a coating is formed on the surface of the positive electrode active material of lithium oxide by reacting with LiOH for the purpose of improving conductivity. In the present embodiment, the amount of coating CA [g] is accurately specified, and the amount of coating CA [g] is controlled to improve and homogenize the reaction resistance Rr [mΩ] of the positive electrode plate 3. However, the specific capacity [mAh / g] changes with the change in the amount of coating CA [g]. Therefore, the reference specific capacity [mAh / g], which is the specific capacity of the positive electrode active material without a coating, is obtained. On the other hand, the reference specific capacity [mAh / g] and the actual specific capacity [mAh / g], which is the specific capacity of the positive electrode active material on which a coating is formed that constitutes the actual positive electrode plate 3, are measured. Then, the difference ΔSC [mAh / g] is obtained by subtracting the reference specific capacity [mAh / g] from the actual specific capacity [mAh / g]. The difference ΔSC [mAh / g] is correlated with the amount of coating CA [g]. In addition, the weight of the positive electrode paste [g / m 2 ] and the reaction resistance Rr [mΩ] of the positive electrode plate 3 are also correlated.

[0094] Therefore, in the procedure of positive electrode coating (S13) in the manufacturing process of the positive electrode plate 3, the basis weight [g / m 2 As a result, the reaction resistance Rr [mΩ] of the positive electrode plate 3 is set as the required performance.

[0095] In this embodiment, the reactive resistance Rr [mΩ] of the positive electrode plate 3 is adjusted by adjusting the coating amount CA [g], but the purpose is to adjust the reactive resistance Rr [mΩ], not to obtain the coating amount CA [g]. Therefore, although the coating amount CA [g] is actually obtained, the actual procedure is to obtain the difference ΔSC of the specific capacity [mAh / g] and adjust the difference ΔSC to adjust the coating amount CA [g], rather than using the numerical value as is.

[0096] (Effects of this embodiment) (1) The method for producing the lithium ion secondary battery 1 of this embodiment has the advantage of being able to accurately specify the amount of only the oxide that reacts with LiOH on the surface of the positive electrode active material to form a lithium oxide film.

[0097] (2) In the method for estimating the amount of coating according to the present embodiment, the actual specific capacity SCa [mAh / g] and the reference specific capacity SCr [mAh / g] are calculated. Then, a specific capacity difference calculation step (S16) is provided in which the actual specific capacity SCa [mAh / g] is compared with the reference specific capacity SCr [mAh / g] to obtain the difference ΔSC [mAh / g]. This has the effect of optimizing the reaction resistance Rr [mΩ] of the positive electrode plate 3 based on the difference ΔSC [mAh / g].

[0098] (3) In the step (S16) of calculating the specific capacity difference, the coating amount CA [g] is estimated from the specific capacity difference ΔSC [mAh / g]. This has the effect of making it possible to estimate the actual coating amount CA [g] based on the specific capacity difference ΔSC [mAh / g].

[0099] (4) In the method for estimating the amount of coating in this embodiment, in a so-called ternary positive electrode active material, the reference specific capacity SCr [mAh / g] is determined by testing using the coefficients A, B, and C in the following formula (1). Then, the reference specific capacity SCr [Ah / g] is calculated using SCr=(A×Co ratio)+(B×Ni / Mn ratio)+(C×Li / Me ratio)+constant term... formula (1). This has the effect of making it possible to easily and accurately calculate the reference specific capacity SCr [mAh / g] that serves as the basis for estimating the amount of coating CA [g].

[0100] (5) The difference ΔSC [mAh / g] calculated in the step (S16) of calculating the difference ΔSC [mAh / g] in specific capacity is compared with a preset threshold value Th to determine whether the lithium ion secondary battery 1 is good or bad (S17). This has the effect of making it possible to easily and accurately determine whether the lithium ion secondary battery 1 is good or bad.

[0101] (6) In the step (S17) of determining whether the lithium ion secondary battery 1 is defective, it may be determined that the battery is defective. In this case, the reaction resistance Rr [mΩ] of the positive electrode plate 3 can be set to a predetermined resistance value simply by increasing or decreasing the coating amount in the coating step (S13) of the positive electrode composite paste according to the estimated coating amount CA [g].

[0102] (7) In the step (S17) of determining whether the lithium ion secondary battery 1 is defective, it may be determined that the battery is defective. In this case, the reaction resistance Rr [mΩ] of the positive electrode plate 3 can be set to a predetermined resistance value simply by increasing or decreasing the amount of additive in the nonaqueous electrolyte 13 according to the estimated coating amount CA [g].

[0103] (8) The method for producing a positive electrode plate for a lithium ion secondary battery according to claim 1, wherein the oxide that reacts with the LiOH to form a lithium oxide film is WO3. (9) In accordance with the principles of the present invention, any oxide that reacts with LiOH to form a lithium oxide film can be used. Therefore, it is not limited to WO3, and may be ZrO2, H3PO4, TiO2, etc.

[0104] (10) The method for estimating the coating amount according to the present embodiment can be incorporated into the manufacturing process of the lithium ion secondary battery 1. This has the effect of making it possible to manufacture lithium ion secondary batteries in which the reaction resistance Rr [mΩ] of the positive electrode plate 3 is small and has no variation.

[0105] (11) The coating amount estimation device 70 of this embodiment includes a processing unit 80 that is a control device equipped with a computer. The processing unit 80 functions as an actual specific capacity measurement means, a reference specific capacity calculation means, and a specific capacity difference calculation means. Then, a coating amount estimation unit 84, which is a specific capacity difference calculation means, calculates a specific capacity difference ΔSC [Ah / g]. Furthermore, the coating amount CA [g] is estimated. Therefore, by including the coating amount estimation device 70 of this embodiment, it is possible to manufacture a lithium ion secondary battery in which the reaction resistance Rr [mΩ] of the positive electrode plate 3 is small and has no variation.

[0106] (Another example) In this embodiment, a so-called ternary positive electrode active material mainly composed of Ni, Mn, and Co is used, and WO3 is added to form a coating on the surface of the positive electrode active material. The positive electrode active material of the present invention is not limited to a material having a lithium transition metal oxide containing all of Ni, Co, and Mn. The positive electrode active material of the present invention can be implemented as long as it is a positive electrode active material whose specific capacity changes depending on the Li / Me ratio, which is the weight ratio of Li to the total metal when Me is the total amount of metal. For example, the present invention can be implemented even if the positive electrode active material is LiMnO4, LiFePO4, etc.

[0107] In this embodiment, the positive electrode active material is a so-called ternary material mainly composed of Ni, Mn, and Co. The reference specific capacity SCr [mAh / g] is estimated by the illustrated formula (1) "SCr = (A x Co ratio) + (B x Ni / Mn ratio) + (C x Li / Me ratio) + constant term". However, the estimation of the reference specific capacity SCr [mAh / g] is not limited to this.

[0108] If the positive electrode active material is not limited to a ternary system mainly composed of Ni, Mn, and Co, but is limited to any of these metals or contains other types of metals, the standard specific capacity SCr [mAh / g] may be calculated using the above formula (1) as is. Alternatively, the standard specific capacity SCr [mAh / g] may be calculated using a different formula suited to that case.

[0109] ○ It can also be calculated using a simple formula such as "SCr = (C × Li / Me ratio) + constant term". The oxide that reacts with LiOH to form a lithium oxide film is not limited to WO3, but may also be ZrO2, H3PO4, TiO2, or the like.

[0110] The present invention is characterized in that the reaction resistance Rr [mΩ] of the positive electrode plate 3 is made small and uniform by estimating the coating amount CA [g], but it is not necessary to actually obtain the coating amount CA [g]. Also, if necessary, the coating amount CA [g] may be actually displayed.

[0111] In this embodiment, the coating weight [g / m 2 However, for example, the amount of an additive added to the nonaqueous electrolyte 13 may be adjusted to adjust the reaction resistance Rr [mΩ] of the positive electrode plate 3. In addition, the present invention is not limited to these, and a method for adjusting the reaction resistance Rr [mΩ] of the positive electrode plate 3, such as adjusting the composition of the positive electrode composite paste, may be used.

[0112] The flowcharts shown in FIGS. 7 and 8 are examples of the method for manufacturing a lithium-ion secondary battery of the present invention, and the method for manufacturing a lithium-ion secondary battery of the present invention is not limited thereto, and each step can be added, deleted, or modified.

[0113] The numerical values ​​and numerical ranges shown in the present embodiment are merely examples and may be optimized as appropriate by those skilled in the art. In addition, those skilled in the art may add, delete, or modify the configuration without departing from the scope of the claims. [Explanation of symbols]

[0114] SCa[mAh / g]…Actual specific capacity SCr[mAh / g]…Reference specific capacity ΔSC[mAh / g]…Difference Me…The sum of the masses of Ni, Mn, and Co A, B, C...coefficients Standard specific capacity SCr=(A×Ni / Mn ratio)+(B×Co / Mn ratio)+(C×Li / Me ratio)+constant term…Equation (1) Rr…Resistance 1...Lithium-ion secondary battery 11…Battery case 12...Electrode body 13...Nonaqueous electrolyte 14…Positive external terminal 15...Negative external terminal 16…Positive current collecting terminal 17...Negative current collecting terminal 2...Negative electrode plate 21...Negative electrode current collector 21a…Metal foil 22...Negative electrode composite material layer 23...Negative electrode current collector 3…Positive electrode plate 31...Positive electrode current collector 32...Positive electrode mixture layer 33…Positive electrode current collector 4…Separator 50…Positive electrode plate manufacturing equipment 60...Measurement charging / discharging device 61...Voltage measuring instrument 62…Current measuring device 63…Temperature measuring device 70…Film amount estimation device 80... Processing section 81...SOC adjustment section 82...Reference specific capacity calculation section 83…Actual capacity measurement section 84...Coating amount estimation section 85...Threshold setting section 86…Good / bad judgment section 90...Storage section 91…Reference specific capacity 92…Decision threshold

Claims

1. A method for manufacturing a positive electrode plate of a lithium ion secondary battery, comprising estimating an amount CA [g] of a coating of lithium oxide formed by reacting with LiOH on a surface of a particle of a positive electrode active material of the lithium ion secondary battery, the method comprising the steps of: a positive electrode kneading step of kneading the particles of the positive electrode active material as a raw material with a secondary material to produce a positive electrode mixture paste; a positive electrode coating step of coating a positive electrode current collector with the positive electrode mixture paste produced in the positive electrode kneading step; an actual specific capacity measuring step of measuring an actual specific capacity SCa [mAh / g] of the positive electrode composite paste applied to the positive electrode current collector; a reference specific capacity calculation step of calculating a reference specific capacity SCr [mAh / g] from a composition ratio of metals constituting the particles of the raw material positive electrode active material on which no coating film is formed; a specific capacity difference calculation step of comparing the actual specific capacity SCa [mAh / g] measured in the actual specific capacity measurement step with the reference specific capacity SCr [mAh / g] calculated in the reference specific capacity calculation step to obtain a difference ΔSC [mAh / g]; A method for manufacturing a positive electrode plate for a lithium ion secondary battery, comprising:

2. a coating amount estimating step of estimating the coating amount CA [g] from the specific capacity difference ΔSC [mAh / g] calculated in the specific capacity difference calculating step; The method for manufacturing a positive electrode plate of a lithium ion secondary battery according to claim 1, further comprising:

3. The positive electrode active material is mainly composed of Ni, Mn, and Co, In the reference specific capacity calculation step, the reference specific capacity SCr [mAh / g] is calculated by a test based on a metal composition ratio consisting of a Co ratio, a Ni / Mn ratio, and a Li / Me ratio, where Me is the sum of the masses of Ni, Mn, and Co, and the coefficients A, B, and C in the following formula (1) are calculated: SCr=(A×Co ratio)+(B×Ni / Mn ratio)+(C×Li / Me ratio)+constant term…Equation (1) 2. The method for manufacturing a positive electrode plate of a lithium ion secondary battery according to claim 1, wherein the standard specific capacity SCr [Ah / g] is calculated by:

4. 4. The method for manufacturing a positive electrode plate of a lithium ion secondary battery according to claim 3, further comprising a quality determination step of determining whether the lithium ion secondary battery is good or bad by comparing the difference ΔSC [mAh / g] calculated in the specific capacity difference calculation step with a preset threshold value Th.

5. 5. The method for manufacturing a positive electrode plate for a lithium ion secondary battery according to claim 4, wherein, when the lithium ion secondary battery is determined to be defective in the quality determination step, the coating amount of the positive electrode composite paste in the positive electrode coating step is increased or decreased according to the calculated specific capacity difference ΔSC [mAh / g].

6. The method for manufacturing a positive electrode plate for a lithium ion secondary battery according to claim 4, characterized in that, when the lithium ion secondary battery is determined to be defective in the quality determination process, the amount of additive to the electrolyte is increased or decreased according to the calculated specific capacity difference ΔSC [mAh / g].

7. The oxide that reacts with LiOH to form a lithium oxide film is WO ３ 2. The method for producing a positive electrode plate of a lithium ion secondary battery according to claim 1,

8. The oxide that reacts with LiOH to form a lithium oxide film is ZrO ２ , H ３ P.O. ４ , TiO ２ 2. The method for producing a positive electrode plate for a lithium ion secondary battery according to claim 1, wherein the positive electrode plate is a positive electrode plate for a lithium ion secondary battery.

9. A method for producing a lithium ion secondary battery, comprising the method for producing a positive electrode plate for a lithium ion secondary battery according to claim 1.

10. A control device having a computer, An estimation device for estimating an amount CA [g] of a coating of lithium oxide formed by a reaction with LiOH on a surface of a particle of a positive electrode active material of a lithium ion secondary battery, the estimation device comprising: The control device an actual specific capacity measuring means for measuring an actual specific capacity SCa [mAh / g] of a positive electrode composite paste produced by kneading particles of the positive electrode active material as a raw material with a sub-material and coating the positive electrode composite paste on a positive electrode current collector; a reference specific capacity calculation means for calculating a reference specific capacity SCr [Ah / g] from a composition ratio of metals constituting the particles of the raw material positive electrode active material on which no coating film is formed; a specific capacity difference calculation means for calculating a difference ΔSC [Ah / g] between the actual specific capacity SCa [Ah / g] measured by the actual specific capacity measurement means and the reference specific capacity SCr [Ah / g] calculated by the reference specific capacity calculation means; A manufacturing apparatus for a positive electrode plate of a lithium ion secondary battery, characterized in that it functions as a coating amount estimation means for estimating the coating amount CA [g] from the specific capacity difference ΔSC [Ah / g] calculated by the specific capacity difference calculation means.

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