Method of inspecting lithium ion secondary battery and method of manufacturing lithium ion secondary battery

Abstract

To easily and accurately estimate and inspect reaction resistance RR [Ω] in manufacturing processes of a lithium ion secondary battery.SOLUTION: A method of inspecting a lithium ion secondary battery includes: a dQ / dV preliminary measurement step (S5) of preliminary measuring dQ / dV [Ah / V] in charge / discharge of amorphous carbon; a coat-derived peak range estimation step (S6) of estimating a coat-derived peak range [V] of the amorphous carbon; a dQ / dV measurement step (S7) of measuring dQ / dV [Ah / V] in charge / discharge of an object to be inspected; a peak area calculation step (S8) of determining an integrated value of a graph as a peak area in the coat-derived peak range [V] of dQ / dV [Ah / V]; a peak area / reaction resistance relationship estimation step (S9) of determining a peak area / reaction resistance relationship in advance in a reference lithium ion secondary battery; and a reaction resistance relationship estimation step (S10) of estimating the reaction resistance RR [Ω] of the lithium ion secondary battery as an object to be inspected.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a method for inspecting a lithium ion secondary battery and a method for manufacturing a lithium ion secondary battery. More specifically, in the manufacturing process of a lithium ion secondary battery, the present invention relates to a method for inspecting a lithium ion secondary battery and a method for manufacturing a lithium ion secondary battery that can estimate and inspect reaction resistance.

Background Art

[0002] Lithium ion secondary batteries are widely used because of their large battery capacity and the ability to charge and discharge at high currents. Such a lithium ion secondary battery is charged by inserting lithium ions of a positive electrode active material into a negative electrode, and is discharged by inserting lithium ions detached from the negative electrode into the positive electrode again.

[0003] Lithium ion secondary batteries contain a carbon material in a negative electrode composite material. In such lithium ion secondary batteries, negative electrode active materials using crystalline graphite have been widely used in recent years. Although graphite has a high charge-discharge capacity, it has problems such as relatively low charge-discharge rate characteristics and the inability to continuously charge and discharge at high currents. Therefore, improvement of graphite particles has been carried out. For example, graphite particles provided with an amorphous coat in which crystalline graphite particles of a negative electrode of a lithium ion secondary battery are coated with amorphous carbon having a low crystallinity have been proposed. It is presumed that such a carbonaceous material having low crystallinity can improve the charge-discharge rate characteristics by increasing the hydrophilicity of the coated graphite particles.

[0004] It has been found that a lithium ion secondary battery has a correlation between the specific surface area BET [m 2 / g] of a negative electrode plate and the reaction resistance R R [Ω]. However, the performance may vary depending on the state of the amorphous coat for each production lot. If the amount of the amorphous coat is too large, the specific surface area BET [m 2 / g] of the negative electrode plate becomes small, and the reaction resistance R R [Ω] becomes large. Therefore, it is desired that the thickness of the amorphous coat is appropriate.

[0005] Patent Document 1 discloses an inspection method for an electrode for a lithium secondary battery, which includes an electrode layer composed of a composite oxide, a conductive polymer material, a conductive auxiliary material, and a polymer binder. In this inspection method for the electrode, X-rays are irradiated onto the surface of the electrode layer, and photoelectrons emitted by the photoelectric effect are detected and the energy of the photoelectrons is analyzed. Thereby, the exclusive area of each of the conductive polymer material, the polymer binder, the conductive auxiliary material, and the composite oxide on the surface of the electrode layer is measured. And, a method of measuring the coverage rate of the conductive polymer material with respect to the composite oxide on the surface of the electrode layer from each exclusive area is adopted. With such a method, the coverage rate of the conductive polymer material can be measured.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] However, the crystallinity of the amorphous coat changes depending on the temperature during firing. For this reason, not only the coverage rate thereof, but also the state of the amorphous coat changes if there are uneven firing or differences in firing temperature. Then, it affects the relationship between the specific surface area BET [m 2 / g] of the negative electrode plate and the reaction resistance R R [Ω], and the correlation may be lost. Furthermore, in the manufacturing process of the lithium ion secondary battery, the specific surface area BET [m 2 / g] of the negative electrode plate may change due to the pressing pressure or the like.

[0008] The inspection method described in Patent Document 1 cannot analyze even such a state. Furthermore, the inspection method as described in Patent Document 1 has a complicated measuring apparatus and operation, and the work is cumbersome.

[0009] The problems to be solved by the method for inspecting a lithium-ion secondary battery and the method for manufacturing a lithium-ion secondary battery according to the present invention are to easily and accurately estimate and inspect the reaction resistance R R [Ω] in the manufacturing process of the lithium-ion secondary battery.

Means for Solving the Problems

[0010] In order to solve the above problems, in the method for inspecting a lithium-ion secondary battery according to the present invention, in a lithium-ion secondary battery provided with graphite particles having an amorphous coat, which is a film of amorphous carbon, formed on the surface thereof as a negative electrode active material, a dQ / dV preliminary measurement step of preliminarily measuring a change dV [V] in the negative electrode potential during charging or discharging of the amorphous carbon used as the material of the lithium-ion secondary battery to be inspected and a ratio dQ / dV [Ah / V] of the capacity Q [Ah] to the change; a coat-derived peak range estimation step of estimating a peak range [V] derived from the coat of the amorphous carbon based on the result of the dQ / dV preliminary measurement step; a dQ / dV measurement step of measuring dQ / dV [Ah / V] during charging or discharging of the lithium-ion secondary battery to be inspected; a peak area calculation step of obtaining, as a peak area S, an integrated value of a graph in the peak range [V] of dQ / dV [Ah / V] obtained in the coat-derived peak range estimation step in the dQ / dV measurement step; a peak area / reaction resistance relationship estimation step of preliminarily obtaining a peak area / reaction resistance relationship, which is a relationship between the peak area S calculated in the peak area calculation step and the reaction resistance R P [Ω], in a reference lithium-ion secondary battery of the same type as the lithium-ion secondary battery to be inspected; and a reaction resistance estimation step of estimating the reaction resistance R P [Ω] of the lithium-ion secondary battery to be inspected based on the peak area S and the peak area / reaction resistance relationship. The method is characterized by comprising the above steps. R [Ω] and the peak area / reaction resistance relationship. The method is characterized by comprising the above steps. P Based on the peak area S calculated in the peak area calculation step and the peak area / reaction resistance relationship, the reaction resistance R R [Ω] of the lithium-ion secondary battery to be inspected is estimated.

[0011] Further, the reaction resistance R estimated in the reaction resistance estimation step RIt may also include a non-defective product identification step of comparing [Ω] with a preset threshold value Th to identify non-defective products and defective products. Further, the peak area / reaction resistance relationship in the peak area / reaction resistance relationship estimation step is based on the plotted points obtained by measuring the peak area S P and the reaction resistance R R [Ω] in a plurality of the reference lithium ion secondary batteries, and the relationship between the peak area S P and the reaction resistance R R [Ω] can also be obtained as a relational expression. In this case, the relational expression can also be obtained as a linear function of the peak area S P and the reaction resistance R R [Ω].

[0012] The coating-derived peak range in the coating-derived peak range estimation step may be set to 2.75 to 2.95 [V]. Further, in the present invention, there is provided a method for manufacturing a lithium ion secondary battery including the method for inspecting a lithium ion secondary battery. When a product is identified as a defective product in the non-defective product identification step, the reaction resistance R R [Ω] of the lithium ion secondary battery is corrected to a preset threshold value, and the manufacturing conditions are fed back to other manufacturing steps of the lithium ion secondary battery.

[0013] When a product is identified as a defective product in the non-defective product identification step, the correction of the manufacturing conditions can be the correction of the pressing pressure in the pressing step of the negative electrode plate or the electrode body of the lithium ion secondary battery.

Advantages of the Invention

[0014] According to the method for inspecting a lithium ion secondary battery and the method for manufacturing a lithium ion secondary battery of the present invention, in the manufacturing process of a lithium ion secondary battery, the reaction resistance can be easily and accurately estimated and inspected.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Mode for Carrying Out the Invention

[0016] Hereinafter, a method for inspecting and manufacturing the lithium-ion secondary battery of the present invention will be described with reference to FIGS. 1 to 7 according to an example of the manufacturing method of the lithium-ion secondary battery 1. (Outline of the Present Embodiment) FIG. 1 is a perspective view showing an outline of the external configuration of the lithium-ion secondary battery 1 of the present embodiment. FIG. 2 is a schematic diagram showing the configuration of the wound electrode body.

[0017] As briefly described in the prior art, the lithium-ion secondary battery 1 contains a carbon material composed of crystalline graphite particles GP serving as nuclei of a negative electrode active material such as graphite in the negative electrode composite material layer 22. The crystalline graphite particles GP have problems such as a high discharge capacity but a low charge-discharge rate characteristic, which is a characteristic of being able to continuously charge and discharge a large current. Therefore, the graphite particles GP have been improved. For example, a negative electrode active material provided with an amorphous coat AC in which the graphite particles GP are coated with a coating NC of amorphous carbon in an amorphous state with a low crystallinity has been proposed. It is presumed that the amorphous carbon having such a low crystallinity can improve the charge-discharge rate characteristic by enhancing the Li acceptance property of the negative electrode active material.

[0018] The lithium-ion secondary battery 1 has a correlation with the specific surface area BET [m 2 / g] of the negative electrode plate 2 and the reaction resistance R R [Ω]. However, the performance may vary depending on the state of the amorphous coat for each production lot. Basically, when the amount of the amorphous coat AC is large, the specific surface area BET [m 2 / g] of the negative electrode plate 2 becomes small, and the reaction resistance R R [Ω] becomes large.

[0019] <Relationship between the coating amount [g] of the amorphous coat AC and the specific surface area [m 2 / g]> Figure 3 is a graph showing the relationship between the average diameter (d 50 ) D [μm] of the graphite particles GP, the specific surface area BET [m 2 / g] of the negative electrode plate 2, and the coating amount Ac [g] of the amorphous coat AC.

[0020] The surface of the crystalline graphite particles GP is inherently uneven and has a large specific surface area BET [m 2 / g]. Therefore, by applying the amorphous coat, the unevenness on the surface is reduced, and the specific surface area BET [m 2 / g] is reduced. For this reason, as shown in Figure 3, if the same average diameter (d 50 ) D [μm], the specific surface area BET [m 2When the coating amount Ac [g] of amorphous carbon is small, the originally rough surface of the crystalline graphite particles GP is exposed. For example, when the average diameter is D1 [μm], in P2 where the coating amount Ac [g] is small, the BET specific surface area [m 2 / g] of the graphite particles GP becomes larger compared to P5.

[0021] Conversely, when the BET specific surface area [m 2 / g] of the negative electrode active material is large, the originally rough surface of the crystalline graphite particles GP is covered with amorphous carbon having a smooth surface. For example, in P8 where the coating amount Ac [g] is large, the BET specific surface area [m 2 / g] of the negative electrode active material becomes smaller compared to P5.

[0022] <The average diameter (d 50 ) D [μm] of the graphite particles GP and the specific surface area [m 2 / g]> Note that on the premise that the average diameter (d 50 ) D [μm] of the graphite particles GP increases, the surface area [m 2 per unit mass [g] becomes smaller, so the BET specific surface area [m 2 / g] becomes smaller. Conversely, when the average diameter (d 50 ) D [μm] of the graphite particles GP decreases, the surface area [m 2 per unit mass [g] becomes larger, so the BET specific surface area [m 2 / g] becomes larger.

[0023] <The shape of the negative electrode active material and the specific surface area [m 2 / g]> However, the crystallinity of the amorphous coat AC changes depending on the temperature during firing. For this reason, not only the coating rate but also the state of the amorphous coat changes due to uneven firing or differences in firing temperature. As a result, it may affect the relationship between the BET specific surface area [m 2 / g] of the negative electrode plate and the reaction resistance R R [Ω], and the correlation may be lost.

[0024] Therefore, it is also possible to irradiate the surface of the negative electrode plate 2 with X-rays as in the prior art, detect the photoelectrons emitted by the photoelectric effect, and analyze the energy of the photoelectrons. However, such a device is costly and the inspection work is extremely complicated, making it difficult to implement in the manufacturing process of the lithium-ion secondary battery 1.

[0025] Furthermore, in the pressing process during the manufacturing process of the negative electrode plate 2 and the pressing process after winding the electrode body 12, due to the pressing pressure, the negative electrode active material is crushed and a new surface is created, and the specific surface area BET [m 2 / g] increases. It is difficult to predict this at the stage of the graphite particles GP and the amorphous coat AC in the raw material stage.

[0026] <The principle of the method for estimating the reaction resistance R R [Ω] of the present embodiment> As described above, it was difficult to accurately estimate the reaction resistance R R [Ω] by the conventional inspection method for superficially inspecting the negative electrode active material. Therefore, the present inventors focused on the difference in the electrochemical reaction between crystalline graphite and amorphous carbon, and found a method for accurately estimating the reaction resistance R R [Ω].

[0027] Figure 4 is a graph showing the relationship between the negative electrode potential [V vs Li / Li + and dQ / dV [Ah / V]. The potential on the horizontal axis is the average reaction potential based on the potential at which the oxidation-reduction reaction of lithium occurs, and the unit is [V vs Li / Li +It is represented by []. It is a concept representing the electrical potential energy at which the intercalation reaction of lithium occurs. The vertical axis indicates dQ / dV at that potential. In the present embodiment, first, the differences in the electrochemical reactions between crystalline graphite and amorphous carbon were determined by the difference in dQ / dV in the change of the negative electrode potential [V] in the experimental cell. Graph G1 is a graph showing the relationship between the negative electrode potential [V] of amorphous carbon itself and dQ / dV. Graph 2 is a graph showing the relationship between the negative electrode potential [V] of crystalline graphite itself and dQ / dV. Graph G3 is a graph showing the relationship between the negative electrode potential [V] of crystalline graphite coated with crystalline graphite and dQ / dV.

[0028] As a result of the experiment, as shown in FIG. 4, in the amorphous carbon shown in graph G1 and the crystalline graphite shown in graph G2, the reactions of dQ / dV at the negative electrode potential [V vs Li / Li + were found to be different. Particularly at a specific negative electrode potential [V vs Li / Li + , while a peak is observed in the dQ / dV of amorphous carbon, no such peak is observed in crystalline graphite. In the entire battery cell, the electrochemical reactions of both the amorphous coat AC made of amorphous carbon and the graphite particles GP made of crystalline graphite appear, and the peak of dQ / dV of only amorphous carbon is potentialized. However, when paying attention to the dQ / dV at a specific negative electrode potential [V vs Li / Li + (coat-derived peak range), the difference in the electrochemical reaction of the amorphous coat AC made of amorphous carbon becomes clear. From the difference in the electrochemical reaction of the amorphous coat AC, it was found that the reaction resistance R R [Ω] state can be directly and accurately estimated.

[0029] (Configuration of the present embodiment) <Configuration of the lithium-ion secondary battery 1> Hereinafter, the manufacturing method of the lithium-ion secondary battery 1 of the present embodiment will be described in detail.

[0030] FIG. 1 is a perspective view showing an outline of the external configuration of the lithium-ion secondary battery 1 of the present embodiment. First, the configuration of the lithium-ion secondary battery 1 of the present embodiment, which is an example of the present invention, will be described.

[0031] As shown in FIG. 1, the lithium-ion secondary battery 1 is configured as a cell battery. The lithium-ion secondary battery 1 includes a plate-shaped rectangular parallelepiped battery case 11 having an opening on the upper side. An electrode body 12 is housed inside the battery case 11. The battery case 11 is filled with a non-aqueous electrolyte 13 from a liquid injection hole. The battery case 11 is made of a metal such as an aluminum alloy and forms an electric tank 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 electric 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 the positive electrode current collecting portion 33 (see FIG. 2) of the electrode body 12. The negative electrode current collector terminal 17 is electrically connected to the negative electrode current collecting portion 23 (see FIG. 2) of the electrode body 12.

[0032] <Electrode body 12> FIG. 2 is a schematic diagram showing the configuration of the wound electrode body 12. The electrode body 12 is formed by laminating a large number of negative electrode plates 2, positive electrode plates 3, and separators 4 disposed therebetween. The laminated negative electrode plates 2, positive electrode plates 3, and separators 4 are wound to form a flat shape. The negative electrode plate 2 has a negative electrode composite material layer 22 formed on a negative electrode current collector 21 made of a copper foil serving as a base material. A negative electrode current collecting portion 23 is provided on one end side in the width direction W (winding axis direction) orthogonal to the winding direction L. The negative electrode current collecting portion 23 has a configuration in which the negative electrode composite material layer 22 is not formed and the negative electrode current collector 21 is exposed.

[0033] The positive electrode plate 3 has a positive electrode mixture layer 32 formed on a positive electrode current collector 31 made of an aluminum foil serving as a base material. As shown in FIG. 2, a positive electrode current collector portion 33 is provided on the other end side (the side opposite to the negative electrode current collector portion 23) in the width direction W (the winding axis direction) orthogonal to the direction (winding direction L) in which the positive electrode current collector 31 is wound. In the positive electrode current collector portion 33, the positive electrode mixture layer 32 is not formed and the metal of the positive electrode current collector 31 is exposed.

[0034] <Laminated structure of the electrode body 12> As shown in FIG. 2, the basic configuration of the electrode body 12 of the lithium ion secondary battery 1 includes a negative electrode plate 2, a positive electrode plate 3, and a separator 4.

[0035] The negative electrode plate 2 has negative electrode mixture layers 22 on both sides of a negative electrode current collector 21 serving as a negative electrode base material. One end portion of the negative electrode current collector 21 is a negative electrode current collector portion 23 where the metal is exposed. The positive electrode plate 3 has positive electrode mixture layers 32 on both sides of a positive electrode current collector 31 serving as a positive electrode base material. The other end portion of the positive electrode current collector 31 is a positive electrode current collector portion 33 where the metal is exposed.

[0036] The negative electrode plate 2 and the positive electrode plate 3 are stacked via a separator 4 to form a laminate. As shown in FIG. 2, this laminate is wound in the longitudinal direction around a winding axis to form a wound-type electrode body 12 that is shaped flat as shown in FIG. 2.

[0037] <Non-aqueous electrolyte 13> The non-aqueous electrolyte 13 of the lithium-ion secondary battery 1 according to the present embodiment shown in FIG. 1 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, trifluoropropylene carbonate, chain carbonates such as diethyl carbonate, dimethyl carbonate, ethyl methyl carbonate, dipropyl carbonate, ether compounds such as tetrahydrofuran, 2-methyltetrahydrofuran, dimethoxyethane, sulfur compounds such as ethyl methyl sulfone, butane sultone, or phosphorus compounds such as triethyl phosphate, trioctyl phosphate, etc. can be mentioned. As the non-aqueous electrolyte 13, these can be used by mixing one or more of them. Note that the composition of the non-aqueous electrolyte 13 is not limited to this.

[0038] <Constituent elements of the electrode body 12> Next, the negative electrode plate 2, the positive electrode plate 3, and the separator 4, which are the constituent elements constituting the electrode body 12, will be described.

[0039] <Negative electrode plate 2> As shown in FIG. 2, negative electrode composite material layers 22 are formed on both sides of a negative electrode current collector 21, which is a negative electrode base material, to form the negative electrode plate 2. In the source process (FIG. 5: S2), a negative electrode composite material paste is applied to the negative electrode current collector 21 to form the negative electrode composite material layer 22. Then, through a drying process, a pressing process, and a cutting process, the negative electrode plate 2 is completed.

[0040] <Negative electrode current collector 21> The negative electrode current collector 21 is composed of a Cu foil in the present embodiment. The negative electrode current collector 21 serves as a base as an aggregate of the negative electrode composite material layer 22 and has a function of a current collecting member that collects electricity from the negative electrode composite material layer 22. One end portion of the negative electrode current collector 21 is a negative electrode current collecting portion 23 in which a metal surface is exposed without the negative electrode composite material layer 22 being formed. That is, the negative electrode active material particles are electrically connected to the negative electrode external terminal 15 through the negative electrode current collector 21, the negative electrode current collecting portion 23, and the negative electrode current collecting terminal 17.

[0041] <Negative electrode composite material layer 22> The negative electrode composite material layer 22 is composed of a negative electrode active material as a raw material, a binder (binding material) serving as an auxiliary material here, an additive, and the like. The raw material and the auxiliary material are mixed with an organic solvent or the like and kneaded to produce a negative electrode composite material paste. This negative electrode composite material paste is applied to the negative electrode current collector 21. The applied negative electrode composite material paste is dried and shaped by pressing to complete the negative electrode plate 2.

[0042] <Negative electrode active material> In this embodiment, the negative electrode active material is powdery graphite particles GP made of graphite (graphite) having a layered structure or the like, and lithium ions Li + is a material capable of occluding and releasing.

[0043] <Amorphous carbon film NC> On the surface of the graphite particles GP, an amorphous carbon film NC is formed. This amorphous carbon film NC can reduce the reaction resistance R R [Ω] between the graphite particles GP and the non-aqueous electrolyte 13. On the other hand, although lithium ions can be inserted into the amorphous carbon film NC itself, lithium ions that are not released again are generated, increasing the irreversible capacity IC [Ah]. Therefore, if the film amount Ac [g] of the film NC is too large, the irreversible capacity increases.

[0044] Generally, the graphite particles GP of the negative electrode active material are incorporated as a raw material of the negative electrode composite material paste in a state where an amorphous carbon film NC is formed in advance. At this time, the thickness, addition amount, etc. of the amorphous carbon film NC may be specified in the specification of the raw material in advance. In this case, the film amount Ac [g] can be calculated based on the specification. However, there may be cases where such specifications are not clear. In this case, it is necessary to estimate the film amount Ac [g]. Therefore, the average diameter (d 50 ) D [μm], which is the median diameter of the graphite particles GP on which the amorphous carbon film NC is formed, is measured. In the present application, the average diameter (d 50 ) D [μm] is the median diameter (d 50) is referred to as

[0045] <Specific surface area [m 2 / g]> This amorphous carbon film NC has a hard but brittle property. During the kneading of the negative electrode composite paste, or during coating and the forming press after drying, it is crushed and broken, and the specific surface area BET [m 2 / g] increases.

[0046] Specific surface area BET [m 2 / g] is represented by the area per unit mass. There are methods such as the adsorption method, the wet heat method, and the reaction method for specific surface area analysis. The adsorption method is a method of adsorbing molecules with known adsorption occupation area on the surface of powder particles at the temperature of liquid nitrogen and determining the specific surface area of the sample from the amount. The adsorption method includes the BET method and the Langmuir method. The most commonly used method in specific surface area analysis is the BET method based on the physical adsorption of an inert gas at low temperature and low humidity.

[0047] In this embodiment, a method of obtaining the specific surface area of powder by the BET method (Berunauer Emmett and Teller’s method, gas adsorption method) is used. The BET specific surface area measuring device uses Quantasorb manufactured by Quanta chrome, and nitrogen gas is used as the adsorption gas.

[0048] <Positive electrode plate 3> As shown in FIG. 2, the positive electrode plate 3 is composed of a positive electrode current collector 31 as a positive electrode substrate and a positive electrode composite layer 32 coated thereon. In the source process (FIG. 5: S1), the positive electrode composite paste is coated on the positive electrode current collector 31. Then, after passing through the drying process, the pressing process, and the cutting process, the positive electrode plate 3 is completed. The manufacturing method of the positive electrode plate 3 of this embodiment is carried out during the manufacturing process of this positive electrode plate 3, which will be described in detail later.

[0049] <Positive electrode current collector 31> A positive electrode plate 3 is formed by forming positive electrode mixture layers 32 on both sides of a positive electrode current collector 31 which is a positive electrode base material. In the embodiment, the positive electrode current collector 31 is made of Al foil. The positive electrode current collector 31 serves as a base as an aggregate of the positive electrode mixture layer 32 and has a function of a current collecting member for collecting electricity from the positive electrode mixture layer 32.

[0050] First, although the positive electrode base material constituting the positive electrode current collector 31 is exemplified by Al foil, for example, it may be composed of a conductive material made of a metal with good conductivity. As a material with good conductivity, for example, in addition to Al foil, a material containing an Al alloy can be used. The configuration of the positive electrode current collector 31 is not limited to this.

[0051] <Positive electrode mixture layer 32> The positive electrode mixture layer 32 is formed by coating and drying a positive electrode mixture paste on the positive electrode current collector 31. The positive electrode mixture layer 32 contains, in addition to positive electrode active material particles, additives such as a conductive auxiliary material, a binder, and a dispersant.

[0052] <Composition of positive electrode active material> The positive electrode active material particles contain a layered crystal structure lithium transition metal oxide. 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 exemplifies a ternary system so-called NCM having a lithium transition metal oxide containing all of Ni, Co, and Mn.

[0053] Note that the positive electrode active material of this embodiment is not limited to those having a lithium transition metal oxide containing all of Ni, Co, and Mn. Also, a composition containing, for example, Al may be used in addition to these.

[0054] <Separator 4> The separator 4 is a highly insulating non-woven fabric made of polypropylene or the like, which is a porous resin for holding the non-aqueous electrolyte 13 between the negative electrode plate 2 and the positive electrode plate 3. Further, as the separator 4, a porous polymer film such as a porous polyethylene film, a porous polyolefin film, and a porous polyvinyl chloride film, or a lithium ion or ion conductive polymer electrolyte membrane can be used alone or in combination.

[0055] <Inspection Method of Lithium Ion Secondary Battery 1 of the Present Embodiment> FIG. 5 is a flowchart showing the manufacturing process of the lithium ion secondary battery 1. Hereinafter, with reference to FIG. 1, the manufacturing method and inspection method of the lithium ion secondary battery 1 of the present embodiment will be described in detail.

[0056] <Material Procurement (S1)> In material procurement (S1), amorphous coated graphite, which is a negative electrode active material, is procured, its characteristics are inspected and tested, and it serves as the basis for setting thresholds and the like in the following procedures.

[0057] <Source Process (S2)> In the source process (S2), the negative electrode plate 2, the positive electrode plate 3, and the separator 4, which are power generation elements, are respectively created. For example, for the negative electrode plate 2, while transporting a long sheet of the negative electrode current collector 21 made of copper foil shown in FIG. 2 with a roller, a negative electrode composite paste constituting the negative electrode composite layer 22 is applied onto the negative electrode current collector 21 to form the negative electrode composite layer 22.

[0058] <Assembly Process (S3)> After the negative electrode plate 2, the positive electrode plate 3, and the separator 4 are respectively created in the source process (S2), the process proceeds to the assembly process (S3). First, in the lamination process, the negative electrode plate 2 and the positive electrode plate 3 are overlapped and integrated via the separator 4. The laminate thus created is wound in the winding direction L as shown in FIG. 2 in the winding process. The laminate wound in the winding process is generally in a plate shape. Such a wound body is pressed from the thickness direction by the pressing surfaces of the opposing presses in the wound body pressing process. In the wound body pressing process, in order to accommodate the electrode body 12 in the battery case 11 without a gap, it is pressed until it reaches a specified thickness [mm].

[0059] In the winding press process, when the thickness of the electrode body 12 is adjusted, as shown in FIG. 1, the negative electrode current collecting terminal 17 and the positive electrode current collecting terminal 16 are attached to the electrode body 12, and further, the negative electrode external terminal 15 and the positive electrode external terminal 14 are attached via the lid body. Then, the electrode body 12 is housed in the battery case 11. Then, the lid body is welded to the battery case 11 to seal the opening. At this stage, since the liquid injection port of the lid body is open, the cell is heated in the cell drying process to dry the inside of the cell. When the inside of the cell is dried in the cell drying process, in the liquid injection and sealing process, the non-aqueous electrolyte 13 is injected, and the liquid injection port is sealed and sealed. Thus, the assembly of the lithium ion secondary battery 1 is completed.

[0060] <Initial charging (S4)> In the initial charging (S4), charging is performed for the first time as an activation process of the cell battery after the assembly process. In the initial charging, a predetermined voltage [V] is applied to the negative electrode external terminal 15 and the positive electrode external terminal 14, and lithium ions Li + move from the positive electrode plate 3 to the negative electrode plate 2 to perform charging and activation. At this time, the SEI film is formed.

[0061] <dQ / dV preliminary measurement process (S5)> In the inspection method of the lithium ion secondary battery of the present embodiment, the dQ / dV preliminary measurement process is performed prior to the actual inspection. For convenience of explanation, it is assumed that this is performed at this point, but of course, it can be performed in advance. Here, first, the amorphous carbon used as the material of the same type of lithium ion secondary battery 1 having common characteristics in the same lot as the lithium ion secondary battery 1 to be inspected is measured. The measurement is to measure in advance the dQ / dV [Ah / V], which is the ratio of the change dV [V] in the negative electrode potential [V] during charging or discharging and the difference dQ [Ah] in the capacity Q [Ah] with respect to the change. Here, in order to determine the threshold value as the reference for inspection, a plurality of samples are used to obtain the average value.

[0062] <Coat-derived peak range estimation process (S6)> Next, based on the result of the Q / dV preliminary measurement process, the range of the coat-derived peak [V] of the amorphous carbon is estimated.

[0063] Figure 4 is a graph showing the relationship between the negative electrode potential [V vs Li / Li + and dQ / dV [Ah / V]. The experiment was conducted using a test cell (manufactured by Nippon Tom Cell Co., Ltd., trade name: Tom Cell (registered trademark) TJ-AC) to fabricate a lithium secondary battery. The amorphous carbon itself that constitutes the amorphous coating AC was used as the negative electrode active material. The characteristics in this case are as shown in graph G1. As the negative electrode potential [V vs Li / Li + decreases from 1.0 [V vs Li / Li + , dQ / dV [Ah / V] increases and reaches a peak of 0.0010 [Ah / V] at approximately 0.73 [V]. Further, as the negative electrode potential [V vs Li / Li + decreases, dQ / dV [Ah / V] becomes 0.00075 [Ah / V] at approximately 0.6 [V]. When charging continues further, the negative electrode potential [V vs Li / Li + decreases, and dQ / dV [Ah / V] reverses to an increase. At approximately 0.25 [V vs Li / Li + , dQ / dV [Ah / V] reaches 0.00020 [V vs Li / Li + .

[0064] As can be seen from the above behavior, a peak of dQ / dV [Ah / V] of the amorphous carbon itself can be confirmed in the vicinity of 0.66 - 0.86 [V vs Li / Li + . On the other hand, in the case of crystalline graphite particles GP, as shown in graph G2, a peak can be confirmed in the vicinity of approximately 0.6 [V vs Li / Li + , but no peak can be confirmed at 0.66 - 0.86 [V].

[0065] In the case of the negative electrode active material composed of graphite particles GP coated with amorphous coating AC for reference, as shown in graph G3, no distinct peak of either amorphous carbon or crystalline graphite can be confirmed. However, it can be understood that the dQ / dV [Ah / V] of the negative electrode active material composed of graphite particles GP coated with this amorphous coating AC is potentially affected by the amorphous coating made of amorphous carbon in the range of 0.66 - 0.86 [V].

[0066] Figure 6 is a graph showing the relationship between the negative electrode potential [V] and dQ / dV [Ah / V] of the present embodiment. The horizontal axis represents the voltage [V] of the battery, and the vertical axis represents dQ / dV. Graph G4 is the graph of the present embodiment, and graphs G5 and G6 show the graphs of the comparative examples. As described above, the graph shown in Figure 6 potentially includes the influences of both crystalline graphite and amorphous carbon. However, as can be seen from graph G4 in Figure 6, its peak is not distinct. Note that as shown in Figure 4, in the range of the negative electrode potential of 0.66 to 0.86 [V vs Li / Li + , that is, in terms of the battery voltage, in the range of 2.75 to 2.95 [V], it is known that the coating amount Ac [g] of amorphous carbon, that is, the amorphous coating AC, is reflected. Therefore, in the above-described peak range estimation step (S6) derived from the coating, the peak range derived from the amorphous coating is estimated.

[0067] <dQ / dV measurement step (S7)> In the dQ / dV measurement step (S7), dQ / dV [Ah / V] is analyzed during the first charge after the assembly process of the lithium-ion secondary battery to be actually inspected is completed. Here, similar to the dQ / dV preliminary measurement step, dQ / dV [Ah / V] is analyzed as in Figure 6.

[0068] <Peak area calculation step (S8)> In the peak area calculation step (S8), in the peak range [V] of dQ / dV [Ah / V] obtained in the coating-derived peak range estimation step (S6) in the dQ / dV measurement step (S7), the integrated value of the graph is the peak area S P and is obtained as such. In the present embodiment, it is 2.75 to 2.95 [V] as shown in Figure 6. Note that the peak area S P is an integrated value in calculation and thus has no unit.

[0069] As described above, the graph of dQ / dV measurement in the dQ / dV measurement step (S7) of the lithium-ion secondary battery to be inspected is compared with the graph of dQ / dV measurement in the dQ / dV measurement step of the reference lithium-ion secondary battery 1 shown in the reference FIG. 6. Then, in the peak range derived from the coating, depending on the coating amount Ac [g] of the amorphous coating AC, a difference appears in the graph of dQ / dV [Ah / V]. To compare this, the peak area S P is calculated.

[0070] <Peak Area / Reaction Resistance Relationship Estimation Step (S9)> First, a lithium-ion secondary battery of the same type as the lithium-ion secondary battery 1 to be inspected is referred to as the "reference lithium-ion secondary battery 1". In the peak area / reaction resistance relationship estimation step (S9), in a plurality of reference lithium-ion secondary batteries 1, the peak area S calculated in the peak area calculation step (S8) P and the reaction resistance R R [Ω], a reference value of the peak area / reaction resistance relationship is obtained in advance. In the present embodiment, the reaction resistance R R [Ω] was measured using an experimental cell under the conditions of a temperature of -30 [°C] and an SOC of 60 [%]. As other conditions, the positive electrode used a ternary positive electrode active material NCM with Ni:Co:Mn = 1:1:1. The negative electrode was coated with an amorphous coating of amorphous carbon on natural graphite particles. As the electrolyte, one with LiPF6 + EC:DMC:EMC = 1:1:1 was used.

[0071] FIG. 7 is a graph showing the relationship between the peak area S of dQ / dV [Ah / V] P , the reaction resistance R R [Ω][%]. In the present embodiment, the peak area S P / reaction resistance R R relationship is obtained as a relational expression between the peak area S P and the reaction resistance R R [Ω] based on the plotted points obtained by measuring the peak area S P and the reaction resistance R R [Ω] in a plurality of reference lithium-ion secondary batteries 1. The relational expression is between the peak area S P and the reaction resistance R RIt is obtained as a linear function with slope a and intercept b for [Ω] (Equation 1).

[0072] R R =a·S P +b…(Equation 1) <Reaction Resistance Estimation Step (S10)> In the reaction resistance estimation step (S10), based on the peak area S calculated in the peak area calculation step (S8) and the relationship between the peak area S P and the peak area S P / reaction resistance R R the reaction resistance R R [Ω] of the lithium-ion secondary battery 1 to be inspected is estimated. Here, the estimation is performed based on the reference value of the peak area / reaction resistance relationship derived in the peak area / reaction resistance relationship estimation step (S9).

[0073] Based on the peak area S obtained in the peak area calculation step (S8), the reaction resistance R P [Ω] is estimated by the above (Equation 1). R In the embodiment, as shown in FIG. 7, for example, when the peak area S P = 65, it can be seen that the reaction resistance R R [%] is approximately 90[%] with respect to the reference value. Also, when the peak area S P = 72 shown at point P2, it can be seen that the reaction resistance R R [%] is approximately 102[%] with respect to the reference value. Further, when the peak area S P = 77 shown at point P3, it can be seen that the reaction resistance R R [%] is approximately 109[%] with respect to the reference value.

[0074] <Good Product Identification Step (S11)> In the good product identification step (S11), the estimated reaction resistance R R [Ω] in the reaction resistance estimation step (S10) is compared with a preset threshold value to identify good products and defective products. In this embodiment, the range of good products is set such that the reaction resistance R R [Ω] is 100% ± 5%. For example, when the peak area S P of dQ / dV is 70, the reaction resistance R​R [Ω] is judged to be a good product at 97.7%. Also, the peak area S of dQ / dV P When it is 85, the reaction resistance R R [Ω] is judged to be a defective product at 123%.

[0075] In the embodiment shown in FIG. 7, in the example shown by point P1, it is judged to be a good product, but in the examples shown by point P2 and point P3, it is judged to be a defective product. <Post-process (S13)> In the post-process (S13), when it is identified as a good product in the good product identification process (S11) (S12: YES), subsequently, an aging process and inspections such as the open-circuit voltage OCV [V], internal resistance [Ω], battery capacity [Ah], etc. are performed, and it is shipped as a completed product. The production of the lithium-ion secondary battery 1 of the same lot is also continued under the same production conditions.

[0076] <Manufacturing condition correction (S14)> In the manufacturing condition correction (S14), when it is identified as a defective product in the good product identification process (S11) (S12: NO), it does not proceed to the post-process (13), and the reaction resistance R of the lithium-ion secondary battery 1 R [Ω] The manufacturing conditions are corrected so as to be a preset threshold value. The correction value is fed back to the production process of other lithium-ion secondary batteries of the same lot. After completion, production is started again according to the corrected manufacturing conditions. In this case, if the materials have already been delivered, it may be possible to skip the material delivery (S1) and start from the source process (S2).

[0077] The method of correcting the manufacturing conditions and feedback is not limited. In this embodiment, as an example, when it is identified as a defective product in the good product identification process, the correction of the manufacturing conditions is to correct the pressing pressure in the pressing process of the negative electrode plate or the electrode body of the lithium-ion secondary battery. By increasing the pressing pressure, the graphite particles GP and the amorphous coat AC of the negative electrode are crushed, and a new surface is created on the negative electrode active material, so that the specific surface area BET [m 2 / g] increases. The pressing process may be at the time of manufacturing the negative electrode plate 2 or at the time of pressing the wound electrode body 12.

[0078] Of course, the method of feedback is not limited to the press pressure, and a method such as adjusting the blending of the negative electrode active material in the negative electrode composite paste may also be used. (Operation of this embodiment) This embodiment focuses on the difference in the electrochemical reactions between crystalline graphite and amorphous carbon, and is a method for estimating the accurate reaction resistance R R [Ω]. FIG. 6 is a graph showing the relationship between the negative electrode potential [V] and dQ / dV. In this embodiment, first, the difference in the electrochemical reactions between crystalline graphite and amorphous carbon is obtained for crystalline graphite and amorphous carbon respectively as the difference in dQ / dV in the change of the negative electrode potential [V]. In this case, in a specific range of the negative electrode potential [V], a peak can be seen in the dQ / dV of the amorphous carbon. On the other hand, such a peak is not seen in the crystalline graphite. Therefore, in the entire battery cell, the electrochemical reactions of both the amorphous coat AC made of amorphous carbon and the graphite particles GP made of crystalline graphite appear, and the peak of the dQ / dV of only the amorphous carbon is latent. However, when focusing on the dQ / dV at a specific negative electrode potential [V] (coat-derived peak range), the difference in the electrochemical reaction of the amorphous coat AC made of amorphous carbon becomes clear. From the difference in the electrochemical reaction of the amorphous coat AC, the reaction resistance R R [Ω] state is directly and accurately estimated.

[0079] (Effect of this embodiment) (1) According to the inspection method and manufacturing method of the lithium ion secondary battery 1 of this embodiment, in the manufacturing process of the lithium ion secondary battery 1, the reaction resistance R R [Ω] can be easily and accurately estimated and inspected.

[0080] (2) By simply analyzing dQ / dV in the first charge (S4) in the manufacturing process of the lithium ion secondary battery 1, the reaction resistance R R [Ω] can be estimated and inspected. Therefore, there is an effect that the reaction resistance R R [Ω] can be easily and accurately estimated and inspected without a special device or complicated inspection.

[0081] (3) In particular, instead of obtaining the reaction resistance R R [Ω] indirectly from the state of the conventional amorphous coat AC, the electrochemical reaction of the amorphous coat AC itself is directly measured to obtain the reaction resistance R R [Ω], so that extremely accurate estimation can be performed.

[0082] (4) In the reaction resistance estimation step (S10), based on the peak area S P calculated in the peak area calculation step (S8) and the peak area / reaction resistance relationship, the reaction resistance R R [Ω] of the lithium ion secondary battery to be inspected is estimated. For this reason, there is an effect that the reaction resistance R R [Ω] can be accurately estimated and inspected only by analyzing dQ / dV.

[0083] (5) The peak area / reaction resistance relationship is derived in advance using the same type of reference lithium ion secondary battery 1 in the peak area / reaction resistance relationship estimation step (S9). For this reason, in the actual inspection, from this relationship, the reaction resistance R P can be immediately obtained from the peak area S R [Ω].

[0084] (6) Prior to the inspection, in the dQ / dV preliminary measurement step (S5), the dQ / dV [Ah / V] during charge and discharge of the amorphous carbon used as the material of the lithium ion secondary battery 1 is measured and analyzed in advance. Then, in the coat-derived peak range estimation step (S6), based on the result of the dQ / dV preliminary measurement step, the coat-derived peak [V] range of the amorphous carbon is estimated. And in the actual inspection, the peak area S P can be immediately calculated in the coat-derived peak range. For this reason, in the actual inspection, from this relationship, the reaction resistance R P can be immediately obtained from the peak area S R [Ω].

[0085] (7) In the peak area calculation step (S8), the integral value of the graph is obtained as the peak area S within the peak range [V] of dQ / dV [Ah / V] obtained in the coat-derived peak range estimation step (S6) in the dQ / dV measurement step (S7). P This peak area S P is an index representing the difference in the electrochemical reaction of the amorphous coat AC, and has the effect that the reaction resistance R R [Ω] can be obtained directly and extremely accurately.

[0086] (8) In the non-defective product discrimination step (S11), the reaction resistance R R [Ω] estimated in the reaction resistance estimation step (S10) is compared with a preset threshold Th to discriminate between non-defective and defective products. For this reason, when the first charge (S4) is completed, it is possible to determine whether the manufactured lithium ion secondary battery 1 is a non-defective or defective product. For this reason, there is an effect that defective products are not shipped as products.

[0087] (9) When discriminated as a defective product in the non-defective product discrimination step (S11) (S12: NO), the manufacturing conditions are corrected so that the reaction resistance R R [Ω] of the lithium ion secondary battery 1 becomes a preset threshold Th. Then, it is fed back to the manufacturing process of other lithium ion secondary batteries 1. As a result, there is an effect that it is possible to prevent the lithium ion secondary battery 1 manufactured thereafter from becoming a defective product.

[0088] (10) When discriminated as a defective product in the non-defective product discrimination step (S11) (S12: NO), the correction of the manufacturing conditions is performed by correcting the pressing pressure in the pressing step of the negative electrode plate or the pressing step of the electrode body. For this reason, there is an effect that the inspection result of the non-defective product discrimination step (S11) can be reliably fed back to the manufacturing process.

[0089] (11) In the peak area / reaction resistance relationship estimation step (S9), based on the plotted points obtained by measuring the peak area and the reaction resistance R R [Ω] in a plurality of reference lithium ion secondary batteries, the peak area and the reaction resistance R RIt is obtained as a relational expression of [Ω]. This relational expression is the peak area S P and the reaction resistance R R [Ω], and is obtained as a linear function R R =a·S P +b…(Equation 1). Therefore, there is an effect that the reaction resistance R P from the peak area S R [Ω] can be accurately obtained.

[0090] (12) In the case of a lithium-ion secondary battery, if the coating-derived peak range in the coating-derived peak range estimation step (S6) is set to 2.75 to 2.95 [V], there is an effect that it can be easily carried out without preliminary preparation.

[0091] (13) In this embodiment, since the inspection can be basically performed only by measuring dQ / dV after the first charge (S4), there is an effect that it can be carried out without additional equipment or processes in a conventional manufacturing apparatus.

[0092] (Alternative example) ○ In the dQ / dV measurement step (S7), although the dQ / dV measurement in the first charge (S4) is exemplified, it is not necessarily limited to the first charge (S4), and charging may be performed for dQ / dV measurement. Furthermore, it may be measured during discharge.

[0093] ○ In the manufacturing condition correction (S14), although the adjustment of the press pressure is exemplified, the correction of the manufacturing conditions is not limited to this, and it can also be performed by changing the composition and characteristics of the negative electrode composite paste constituting the negative electrode composite layer 22. In addition, as long as it is an element that can affect the reaction resistance R R [Ω], the manufacturing conditions can be corrected.

[0094] 〇 The lithium-ion secondary battery 1 of this embodiment exemplifies a battery cell that constitutes a battery pack for driving a hybrid vehicle, but the lithium-ion secondary battery may be one used as a single cell. Also, its application may be for stationary use or for use as a power source for portable devices.

[0095] 〇The lithium-ion secondary battery 1 of the present embodiment is exemplified as having a flat and thin rectangular parallelepiped battery case 11, but its shape is not limited to a cylindrical shape or the like. ○The numerical values and numerical ranges of the present embodiment are optimized for the lithium-ion secondary battery in the present embodiment, and can be appropriately optimized by those skilled in the art according to the characteristics of the target battery.

[0096] ○The flowchart shown in FIG. 5 is an example of a manufacturing method including the inspection method of the lithium-ion secondary battery of the present embodiment, and those skilled in the art can add, delete, change the order, or change the procedures. In particular, the dQ / dV preliminary measurement step (S5) and the peak area / reaction resistance relationship estimation step (S9), which are preliminary steps, are shown as part of the inspection step for convenience of explanation, but actually should be performed in advance.

[0097] ○In addition, those skilled in the art can add, delete, or change the configuration without departing from the scope of the claims.

Explanation of Signs

[0098] 1... Lithium-ion secondary battery (cell battery) 11... Battery case 12... Electrode body 13... Non-aqueous electrolyte 14... Positive electrode external terminal 15... Negative electrode external terminal 16... Positive electrode current collector terminal 17... Negative electrode current collector terminal 2... Negative electrode plate 21... Negative electrode current collector 21a... Metal foil 22... Negative electrode composite layer 23... Negative electrode current collecting portion 3... Positive electrode plate 31... Positive electrode current collector 32... Positive electrode composite layer 33... Positive electrode current collecting portion 4... Separator GP... Graphite particles AC... Amorphous coat Ac[g]…(Amorphous carbon) film amount BET[m 2 / g]…(Negative electrode plate) specific surface area D[μm]…(Graphite particle GP) average diameter (d 50 ) R R [Ω]…Reaction resistance S P …Peak area Th…Threshold value

Claims

1. In a lithium-ion secondary battery comprising graphite particles having an amorphous coat, which is an amorphous carbon film, formed on the surface thereof as a negative electrode active material, a dQ / dV preliminary measurement step of preliminarily measuring dQ / dV [Ah / V], which is a ratio of a change dV [V] in the negative electrode potential during charging or discharging of the amorphous carbon used as a material of the lithium-ion secondary battery to be inspected and a capacity Q [Ah] with respect to the change; a coat-derived peak range estimation step of estimating a coat-derived peak range [V] of the amorphous carbon based on the result of the dQ / dV preliminary measurement step; a dQ / dV measurement step of measuring dQ / dV [Ah / V] during charging or discharging of the lithium-ion secondary battery to be inspected; a peak area calculation step of obtaining, as a peak area S, an integrated value of a graph in the coat-derived peak range [V] of dQ / dV [Ah / V] obtained in the coat-derived peak range estimation step in the dQ / dV measurement step; Ｐ and a peak area calculation step of obtaining; in a reference lithium-ion secondary battery of the same type as the lithium-ion secondary battery to be inspected, a peak area / reaction resistance relationship estimation step of preliminarily obtaining a peak area / reaction resistance relationship, which is a relationship between the peak area S Ｐ calculated in the peak area calculation step and a reaction resistance R Ｒ [Ω]; and a reaction resistance estimation step of estimating the reaction resistance R Ｐ [Ω] of the lithium-ion secondary battery to be inspected based on the peak area S Ｒ calculated in the peak area calculation step and the peak area / reaction resistance relationship. A method for inspecting a lithium-ion secondary battery, comprising the steps described above.

2. The method for inspecting a lithium-ion secondary battery according to claim 1, further comprising a non-defective product identification step of comparing the reaction resistance R Ｒ [Ω] estimated in the reaction resistance estimation step with a preset threshold Th to identify non-defective products and defective products.

3. Estimate the peak area / reaction resistance relationship in the peak area / reaction resistance relationship estimation step as the peak area S in a plurality of the reference lithium ion secondary batteries Ｐ and the reaction resistance R Ｒ [Ω], and obtain it as a relational expression between the peak area S Ｐ and the reaction resistance R Ｒ [Ω]. The method for inspecting a lithium ion secondary battery according to claim 1, characterized in that

4. The relational expression is obtained as a linear function of the peak area S Ｐ and the reaction resistance R Ｒ [Ω]. The method for inspecting a lithium ion secondary battery according to claim 3, characterized in that

5. The coat-derived peak range in the coat-derived peak range estimation step is set to 2.75 to 2.95 [V]. The method for inspecting a lithium ion secondary battery according to claim 1, characterized in that

6. A method for manufacturing a lithium ion secondary battery including the method for inspecting a lithium ion secondary battery according to claim 2, wherein when it is identified as a defective product in the non-defective product identification step, the reaction resistance R of the lithium ion secondary battery Ｒ [Ω] is corrected so as to be a preset threshold value, and the manufacturing conditions are fed back to other manufacturing steps of the lithium ion secondary battery. A method for manufacturing a lithium ion secondary battery, characterized in that

7. When it is identified as a defective product in the non-defective product identification step, the correction of the manufacturing conditions is the correction of the pressing pressure in the pressing step of the negative electrode plate or the electrode body of the lithium ion secondary battery. The method for manufacturing a lithium ion secondary battery according to claim 6, characterized in that

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