Inspection Method for Non-Aqueous Electrolyte Secondary Battery

Abstract

To provide a method for inspecting a non-aqueous electrolyte secondary battery, capable of improving inspection accuracy.SOLUTION: Positive electrode capacity and negative electrode capacity are predicted based on manufacturing conditions of a non-aqueous electrolyte secondary battery. An opposing capacity ratio is predicted based on the predicted positive and negative electrode capacities. A voltage drop value based on a voltage value measured in each measurement step and a correction value corresponding to the predicted opposing capacity ratio are calculated, and the voltage drop value is corrected. The non-aqueous electrolyte secondary battery is determined to be normal when the corrected voltage drop value is equal to or less than a threshold.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a method for inspecting a non-aqueous electrolyte secondary battery, and more particularly to a method for inspecting a non-aqueous electrolyte secondary battery that can improve the inspection accuracy of self-discharge inspection.

Background Art

[0002] Conventionally, in a non-aqueous electrolyte secondary battery, since self-discharge increases when there is an internal short circuit, self-discharge inspection of the non-aqueous electrolyte secondary battery is required. As one of the inspection methods for non-aqueous electrolyte secondary batteries, for example, as disclosed in Patent Document 1, there is one including a high-temperature aging step, a first measurement step, a second measurement step, and a determination step. The high-temperature aging step is a step of storing the secondary battery that has been initially charged in a high-temperature environment. The first measurement step is a step of measuring the voltage of the secondary battery stored in the high-temperature environment. The second measurement step is a step of measuring the voltage of the secondary battery after a specified time has elapsed from the first measurement step. And the determination step is a step of determining that the secondary battery is defective when the voltage difference measured in each measurement step is calculated as a voltage drop value and the voltage drop value is greater than a threshold value.

[0003] In particular, for example, as disclosed in Patent Document 1, the voltage drop value may vary depending on the opposing capacity ratio of the secondary battery, and it is disclosed that self-discharge inspection is performed on the condition that the opposing capacity ratio of the secondary battery is within an allowable range. This allowable range is a range in which the influence on the voltage drop value is small, and the variation in the voltage drop value can be suppressed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the invention described in Patent Document 1, even if the opposing capacity ratio of the secondary battery is within the allowable range, an error may occur in the voltage drop value due to the opposing capacity ratio of the secondary battery, resulting in a decrease in inspection accuracy.

Means for Solving the Problems

[0006] The inspection method for a non-aqueous electrolyte secondary battery for solving the above problems is an inspection method for a non-aqueous electrolyte secondary battery including an electrode body including a positive electrode, a negative electrode, and a separator, a non-aqueous electrolyte, and a battery case for housing the electrode body and the non-aqueous electrolyte, the method including: a positive electrode capacity prediction step of predicting the positive electrode capacity of the non-aqueous electrolyte secondary battery based on the manufacturing conditions of the non-aqueous electrolyte secondary battery; a negative electrode capacity prediction step of predicting the negative electrode capacity of the non-aqueous electrolyte secondary battery based on the manufacturing conditions of the non-aqueous electrolyte secondary battery; an opposing capacity ratio prediction step of predicting an opposing capacity ratio based on the positive electrode capacity predicted in the positive electrode capacity prediction step and the negative electrode capacity predicted in the negative electrode capacity prediction step; a first measurement step of measuring the voltage value of the non-aqueous electrolyte secondary battery; a second measurement step of measuring the voltage value of the non-aqueous electrolyte secondary battery when a specified time has elapsed after the first measurement step; a correction step of calculating a voltage drop value based on the voltage value measured in the first measurement step and the voltage value measured in the second measurement step, and a correction value corresponding to the opposing capacity ratio predicted in the opposing capacity ratio prediction step, and correcting the voltage drop value; and a self-discharge determination step of determining that the non-aqueous electrolyte secondary battery is normal when the voltage drop value corrected in the correction step is equal to or less than a threshold value.

[0007] Further, the correction step may be a step of correcting so as to increase the voltage drop value when the opposing capacity ratio predicted in the opposing capacity ratio prediction step is a first opposing capacity ratio greater than a reference opposing capacity ratio, while correcting so as to decrease the voltage drop value when the opposing capacity ratio predicted in the opposing capacity ratio prediction step is a second opposing capacity ratio smaller than the reference opposing capacity ratio.

[0008] Further, based on the manufacturing conditions of the non-aqueous electrolyte secondary battery, an irreversible capacity prediction step for predicting the irreversible capacity of the non-aqueous electrolyte secondary battery, the positive electrode capacity predicted in the positive electrode capacity prediction step, and the irreversible capacity predicted in the irreversible capacity prediction step, a cell capacity prediction step for predicting the cell capacity of the non-aqueous electrolyte secondary battery, a cell capacity measurement step for measuring the cell capacity of the non-aqueous electrolyte secondary battery, and when the cell capacity measured in the cell capacity measurement step is within an allowable range based on the cell capacity predicted in the cell capacity prediction step, a cell capacity determination step for determining that the non-aqueous electrolyte secondary battery is normal may be included.

[0009] Further, the positive electrode capacity prediction step is a step of predicting the positive electrode capacity of the non-aqueous electrolyte secondary battery based on the electrode conditions of the positive electrode as the manufacturing conditions of the non-aqueous electrolyte secondary battery, and the negative electrode capacity prediction step may be a step of predicting the negative electrode capacity of the non-aqueous electrolyte secondary battery based on the electrode conditions of the negative electrode as the manufacturing conditions of the non-aqueous electrolyte secondary battery.

[0010] Further, the positive electrode capacity prediction step is a step of predicting the positive electrode capacity of the non-aqueous electrolyte secondary battery based on at least any one of the material physical properties of the positive electrode, the basis weight of the positive electrode, and the coating area of the positive electrode as the electrode conditions of the positive electrode, and the negative electrode capacity prediction step may be a step of predicting the negative electrode capacity of the non-aqueous electrolyte secondary battery based on at least any one of the basis weight of the negative electrode and the coating area of the negative electrode as the electrode conditions of the negative electrode.

[0011] Further, a high-temperature aging step of storing the charged non-aqueous electrolyte secondary battery in a high-temperature environment may be included. Further, the first measurement step and the second measurement step may be performed when the SOC of the non-aqueous electrolyte secondary battery is 80% to 90%.

Advantages of the Invention

[0012] According to the present invention, the inspection accuracy can be improved.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Embodiments for Carrying Out the Invention

[0014] [First Embodiment] Hereinafter, an embodiment of a method for inspecting a non-aqueous electrolyte secondary battery will be described. <Lithium-ion secondary battery 10> The configuration of the lithium-ion secondary battery that is the premise of this embodiment will be briefly described.

[0015] As shown in FIG. 1, the lithium-ion secondary battery 10 is configured as a single cell battery. The lithium-ion secondary battery 10 includes a rectangular parallelepiped battery case 11 and a lid 12. The battery case 11 has an opening (not shown) on the upper side. The lid 12 seals the opening of the battery case 11. The battery case 11 and the lid 12 are made of a metal such as an aluminum alloy. The lid 12 includes a negative electrode external terminal 13 and a positive electrode external terminal 14 that are used for charging and discharging electric power. The negative electrode external terminal 13 and the positive electrode external terminal 14 may have any shape.

[0016] The lithium-ion secondary battery 10 includes an electrode body 15. The lithium-ion secondary battery 10 includes a negative electrode current collector 16 and a positive electrode current collector 17. The negative electrode current collector 16 connects the negative electrode of the electrode body 15 and the negative electrode external terminal 13. The positive electrode current collector 17 connects the positive electrode of the electrode body 15 and the positive electrode external terminal 14. The electrode body 15 is housed inside the battery case 11. A non-aqueous electrolyte 18 is injected into the battery case 11 through a liquid injection hole (not shown). Thus, the lithium-ion secondary battery 10 includes the non-aqueous electrolyte 18. The lithium-ion secondary battery 10 forms a sealed battery compartment by attaching the lid 12 to the battery case 11. Thus, the battery case 11 houses the electrode body 15 and the non-aqueous electrolyte 18.

[0017] <Non-aqueous electrolyte 18> The non-aqueous electrolyte 18 is a composition in which a supporting salt is contained in a non-aqueous solvent. In the present embodiment, ethylene carbonate (EC) can be used as the non-aqueous solvent. The non-aqueous solvent may be one or more materials selected from the group consisting of propylene carbonate (PC), diethyl carbonate (DEC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), and the like.

[0018] Also, as the supporting salt, LiPF6, LiBF4, LiClO4, LiAsF6, LiCF3SO3, LiC4F9SO3, LiN(CF3SO2)2, LiC(CF3SO2)3, LiI, etc. can be used. Also, one or more lithium compounds (lithium salts) selected from these can be used.

[0019] <Electrode body 15> As shown in FIG. 2, the electrode body 15 includes a negative electrode plate 20, a positive electrode plate 30, and a separator 40. The longitudinal direction of the electrode body 15 is referred to as the "length direction Z". The thickness direction of the electrode body 15 is referred to as the "thickness direction D". The direction orthogonal to the length direction Z and the thickness direction D of the electrode body 15 is referred to as the "width direction W".

[0020] <Negative electrode plate 20> The negative electrode plate 20 functions as an example of the negative electrode of the lithium-ion secondary battery 10. The negative electrode plate 20 includes a negative electrode substrate 21 and a negative electrode composite layer 22. The negative electrode composite layer 22 is formed on both surfaces of the negative electrode substrate 21. The negative electrode substrate 21 includes a negative electrode connection portion 23 that is exposed from the electrode body 15. The negative electrode connection portion 23 is provided at one end in the width direction W of the electrode body 15.

[0021] In this embodiment, the negative electrode substrate 21 is composed of a Cu foil. The negative electrode substrate 21 serves as a base as an aggregate of the negative electrode composite layer 22. The negative electrode substrate 21 has a function of a current collecting member that collects electricity from the negative electrode composite layer 22.

[0022] The negative electrode composite layer 22 has a negative electrode active material. In this embodiment, the negative electrode active material is a material capable of occluding and releasing lithium ions, and a powdery carbon material made of graphite (graphite) or the like is used. The negative electrode plate 20 is manufactured, for example, by kneading a negative electrode active material, a solvent, and a binder, applying the kneaded negative electrode composite material to the negative electrode substrate 21, and drying it.

[0023] <Positive electrode plate 30> The positive electrode plate 30 functions as an example of the positive electrode of the lithium-ion secondary battery 10. The positive electrode plate 30 includes a positive electrode substrate 31 and a positive electrode composite layer 32. The positive electrode composite layer 32 is formed on both surfaces of the positive electrode substrate 31. The positive electrode substrate 31 includes a positive electrode connection portion 33 that is exposed from the electrode body 15. The positive electrode connection portion 33 is provided at the other end in the width direction W of the electrode body 15.

[0024] In the embodiment, the positive electrode substrate 31 is made of an Al foil or an Al alloy foil. The positive electrode substrate 31 serves as a base as an aggregate of the positive electrode composite layer 32. The positive electrode substrate 31 has a function of a current collecting member that collects electricity from the positive electrode composite layer 32.

[0025] The positive electrode composite layer 32 contains a positive electrode active material. The positive electrode active material is a material capable of occluding and releasing lithium, and for example, lithium cobaltate (LiCoO2), lithium manganate (LiMn2O4), lithium nickelate (LiNiO2), etc. can be used. Also, a material obtained by mixing LiCoO2, LiMn2O4, and LiNiO2 at an arbitrary ratio may be used. The positive electrode composite layer 32 contains a conductive material. As the conductive material, for example, carbon black such as acetylene black (AB) and ketjen black, and graphite can be used. The positive electrode plate 30 is produced, for example, by kneading a positive electrode active material, a conductive material, a solvent, and a binder, and applying the kneaded positive electrode composite material to the positive electrode substrate 31 and drying it.

[0026] <Separator 40> The separator 40 holds the non-aqueous electrolyte 18 between the negative electrode plate 20 and the positive electrode plate 30. The separator 40 is a non-woven fabric made of a porous resin such as polypropylene. As the separator 40, 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. When the electrode body 15 is immersed in the non-aqueous electrolyte 18, the non-aqueous electrolyte 18 penetrates from the end portion to the central portion of the separator 40.

[0027] <Manufacturing process of the lithium ion secondary battery 10> Here, an outline of the manufacturing process of the lithium ion secondary battery 10 of the present embodiment will be described. In the present embodiment, a source process is performed. The source process is a process of manufacturing the battery elements of the lithium ion secondary battery 10. Specifically, the source process is a process of manufacturing the negative electrode plate 20 and the positive electrode plate 30 that constitute the battery elements of the lithium ion secondary battery 10.

[0028] When the source process is completed, the lamination process is performed. In the lamination process, the negative electrode plate 20, the separator 40, the positive electrode plate 30, and the separator 40 are laminated in this order, that is, the negative electrode plate 20, the positive electrode plate 30, and the separator 40 are laminated. That is, the electrode body 15 is configured by laminating the negative electrode plate 20 and the positive electrode plate 30 with the separator 40 interposed therebetween. The negative composite material layer 22 and the positive composite material layer 32 are arranged to face each other with the separator 40 interposed therebetween. The negative electrode plate 20 and the separator 40 are arranged such that the negative electrode connection portion 23 protrudes from the separator 40 at one end of the electrode body 15 in the width direction W. The positive electrode plate 30 and the separator 40 are arranged such that the positive electrode connection portion 33 protrudes from the separator 40 at the other end of the electrode body 15 in the width direction W. That is, the electrode body 15 is formed with a negative electrode connection portion 23 in which the negative electrode base material 21 is exposed at one end, and a positive electrode connection portion 33 in which the positive electrode base material 31 is exposed at the other end.

[0029] When the lamination process is completed, the winding process is performed. In the winding process, the electrode body 15 is supported and wound around the winding axis in the width direction W. The electrode body 15 is formed with a flat portion like a track for a race and curved portions formed at both ends thereof.

[0030] When the winding process is completed, the wound body pressing process is performed. The electrode body 15 is pressed and compressed with a force that does not exceed a predetermined pressure from the thickness direction D. In the present embodiment, 100 kN is adopted as the predetermined pressure, but it is not limited thereto.

[0031] Specifically, as shown in FIG. 3, the electrode body 15 is supported around the winding axis and wound in the length direction Z in a state where the negative electrode plate 20 and the positive electrode plate 30 are stacked with the separator 40 interposed therebetween. By applying pressure to the electrode body 15 from the thickness direction D orthogonal to the width direction W, the end portion viewed from the width direction W is shaped into a flat shape like a track for a race.

[0032] When the winding press process is completed, the terminal welding process is performed. In the terminal welding process, the negative electrode connection part 23 and the negative electrode current collector 16 are electrically and mechanically connected by welding. The positive electrode connection part 33 and the positive electrode current collector 17 are electrically and mechanically connected by welding.

[0033] When the terminal welding process is completed, the case insertion process is performed. In the case insertion process, the electrode body 15 is inserted into the battery case 11 in a wound and flattened state and with the negative electrode current collector 16 and the positive electrode current collector 17 connected.

[0034] When the case insertion process is completed, the can sealing welding process is performed. In the can sealing welding process, the battery case 11 and the lid body 12 are sealed by laser welding or the like. At this stage, the non-aqueous electrolyte 18 has not been injected yet, and the injection port of the lid body 12 is open.

[0035] When the can sealing welding process is completed, the cell drying process is performed. In the cell drying process, in order to sufficiently dry the moisture remaining in the battery case, the temperature inside the battery is raised to, for example, about 105°C. In this process, since the temperature is high and the resin of the separator 40 softens, no restraint is applied.

[0036] When the cell drying process is completed, the liquid injection and sealing process is performed. In the liquid injection and sealing process, the non-aqueous electrolyte 18 is injected into the battery case from the injection port of the lid body 12. When the liquid injection is completed, the injection port is sealed. Thus, the assembly of the lithium ion secondary battery 10 is completed, and as will be described later, a cell capacity inspection and a self-discharge inspection are performed.

[0037] <Inspection configuration of the lithium ion secondary battery 10> Next, with reference to FIG. 4, the configuration when the lithium ion secondary battery 10 is inspected will be described.

[0038] As shown in FIG. 4, when the cell capacity inspection and self-discharge inspection of the lithium-ion secondary battery 10 are performed, the plurality of lithium-ion secondary batteries 10 are arranged to be aligned in the thickness direction D by being installed on an inspection jig (not shown). In the present embodiment, 25 lithium-ion secondary batteries 10 can be installed on the inspection jig, but it is not limited thereto. In the present embodiment, the plurality of lithium-ion secondary batteries 10 may be arranged such that a groove-shaped gap is formed between each of the plurality of lithium-ion secondary batteries 10.

[0039] The plurality of lithium-ion secondary batteries 10 are constrained in the thickness direction D depending on the type of process. "Constraining" means directly or indirectly pressing the electrode body 15 from the thickness direction D to compress the separator 40. In the present embodiment, with the plurality of lithium-ion secondary batteries 10 installed, the battery case 11 is pressed in the thickness direction D. The pressing is not limited to a press machine, and may be configured to be tightened with screws by a restraining frame.

[0040] <Inspection method for lithium-ion secondary battery 10> Here, with reference to FIG. 5, the inspection method for the lithium-ion secondary battery 10 will be described. As shown in FIG. 5, first, when the manufacture of the lithium-ion secondary battery 10 is completed, in step S11, a charging process is performed. In the charging process, initial charging is performed for the purpose of forming a SEI (Solid Electrolyte Interphase) film and the like. The initial charging is performed at a relatively low charging rate, and the temperature rise of the lithium-ion secondary battery 10 is suppressed. In the charging process, full charging with a SOC (State Of Charge) of 100% is performed, but for example, it may be SOC 90% or the like. In the present embodiment, the charging process is performed at a normal temperature of about 20°C. In the charging process, the plurality of lithium-ion secondary batteries 10 may be constrained.

[0041] When the charging process is completed, in step S12, a high-temperature aging process is performed. The high-temperature aging process is a process of storing the lithium-ion secondary battery 10 charged in the charging process in a high-temperature environment. In the high-temperature aging process, the lithium-ion secondary battery 10 is chemically stabilized and activated. One of the purposes is that if there is a short circuit between fine electrodes caused by fine metal existing in the electrode, by raising the temperature, the dissolution and precipitation of this metal are accelerated, and the fine short circuit is detected. For this reason, in the high-temperature aging process, for example, in this embodiment, it is carried out while maintaining a high temperature of about 60°C. In this embodiment, in the high-temperature aging process, a plurality of lithium-ion secondary batteries 10 are stored in a high-temperature environment for a predetermined time. In this embodiment, in the high-temperature aging process, the plurality of lithium-ion secondary batteries 10 may not be restrained.

[0042] When the high-temperature aging process is completed, in step S13, a positive electrode capacity prediction process is performed. The positive electrode capacity prediction process is a process of predicting the positive electrode capacity of the lithium-ion secondary battery 10 based on the manufacturing conditions and inspection conditions of the lithium-ion secondary battery 10. That is, the positive electrode capacity prediction process is a process of predicting the positive electrode capacity based on the conditions in the previous processes before the positive electrode capacity prediction process.

[0043] Specifically, the positive electrode capacity can be predicted based on, for example, the electrode conditions of the positive electrode as the manufacturing conditions of the lithium-ion secondary battery 10. The electrode conditions of the positive electrode may include, for example, the material physical properties of the positive electrode, the weight per unit area of the positive electrode, and the coating area of the positive electrode. The material physical properties of the positive electrode are the material physical properties of the positive electrode substrate 31 and the positive electrode composite layer 32. The weight per unit area of the positive electrode is the weight per unit area of the positive electrode composite layer 32 with respect to the positive electrode substrate 31. The coating area of the positive electrode is the coating area of the positive electrode composite layer 32 with respect to the positive electrode substrate 31. The coating area can be calculated from the coating width and the coating length. The positive electrode capacity can be predicted based on, for example, the initial charging capacity as the inspection conditions of the lithium-ion secondary battery 10. The initial charging capacity is the capacity of the initial charging performed in the charging process of step S11.

[0044] When the positive electrode capacity prediction process is completed, in step S14, an irreversible capacity prediction process is performed. The irreversible capacity prediction process is a process of predicting the irreversible capacity of the lithium-ion secondary battery 10 based on the manufacturing conditions and inspection conditions of the lithium-ion secondary battery 10. That is, the irreversible capacity prediction process is a process of predicting the irreversible capacity based on the conditions in the previous processes up to before the irreversible capacity prediction process.

[0045] Specifically, the irreversible capacity can be predicted based on, for example, the electrode conditions of the negative electrode as the manufacturing conditions of the lithium-ion secondary battery 10. The electrode conditions of the negative electrode may include, for example, the material physical properties of the negative electrode, the basis weight of the negative electrode, and the coating area of the negative electrode. The material physical properties of the negative electrode are the material physical properties of the negative electrode substrate 21 and the negative electrode composite layer 22. The basis weight of the negative electrode is the basis weight of the negative electrode composite layer 22 with respect to the negative electrode substrate 21. The coating area of the negative electrode is the coating area of the negative electrode composite layer 22 with respect to the negative electrode substrate 21. The irreversible capacity can be predicted based on, for example, the amount of electrolyte as the manufacturing conditions of the lithium-ion secondary battery 10. The amount of electrolyte is the amount of the non-aqueous electrolyte 18 injected into the battery case in the liquid injection and sealing process. The irreversible capacity can be predicted based on, for example, the high-temperature aging conditions as the inspection conditions of the lithium-ion secondary battery 10. The high-temperature aging conditions may be the time and set temperature for performing high-temperature aging.

[0046] When the irreversible capacity prediction process is completed, in step S15, a negative electrode capacity prediction process is performed. The negative electrode capacity prediction process is a process of predicting the negative electrode capacity of the lithium-ion secondary battery 10 based on the manufacturing conditions of the lithium-ion secondary battery 10. That is, the negative electrode capacity prediction process is a process of predicting the negative electrode capacity based on the conditions in the previous processes up to before the negative electrode capacity prediction process.

[0047] Specifically, the negative electrode capacity can be predicted based on, for example, the electrode conditions of the negative electrode as the manufacturing conditions of the lithium-ion secondary battery 10. The electrode conditions of the negative electrode may include, for example, the basis weight of the negative electrode and the coating area of the negative electrode.

[0048] As the manufacturing conditions and inspection conditions of the lithium-ion secondary battery 10 obtained in steps S13 to S15, they may be measured values from the lithium-ion secondary battery 10 to be inspected or design values of the lithium-ion secondary battery 10 by the designer. As the manufacturing conditions and inspection conditions of the lithium-ion secondary battery 10, measured values may be obtained for each of a plurality of lithium-ion secondary batteries 10 to be inspected. As the manufacturing conditions and inspection conditions of the lithium-ion secondary battery 10, measured values of one or a plurality of representative lithium-ion secondary batteries 10 among a plurality of lithium-ion secondary batteries 10 that are the subject of one inspection may be obtained. As the manufacturing conditions of the lithium-ion secondary battery 10, measured values of one or a plurality of representative lithium-ion secondary batteries 10 among a plurality of lithium-ion secondary batteries 10 included in the manufacturing lot of the lithium-ion secondary battery 10 may be obtained. As the manufacturing conditions of the lithium-ion secondary battery 10, measured values of one or a plurality of representative lithium-ion secondary batteries 10 among a plurality of lithium-ion secondary batteries 10 included in the material lot when manufacturing the electrode body 15 of the lithium-ion secondary battery 10 may be obtained. For each parameter of the manufacturing conditions and inspection conditions of the lithium-ion secondary battery 10, whether to adopt the design value or the measured value may be different, and the object for obtaining the measured value may also be different.

[0049] When the negative electrode capacity prediction process is completed, in step S16, the cell capacity prediction process is performed. The cell capacity prediction process is a process of predicting the cell capacity of the lithium-ion secondary battery 10 based on the positive electrode capacity predicted in step S13 and the irreversible capacity predicted in step S14. Specifically, in the cell capacity prediction process, the capacity obtained by subtracting the irreversible capacity predicted in step S14 from the positive electrode capacity predicted in step S13 is predicted as the cell capacity of the lithium-ion secondary battery 10.

[0050] When the cell capacity prediction process is completed, in step S17, the opposed capacity ratio prediction process is performed. The opposed capacity ratio prediction process is a process of predicting the opposed capacity ratio of the lithium-ion secondary battery 10 based on the positive electrode capacity predicted in step S13, the negative electrode capacity predicted in step S15, and the coated area of the opposed portion between the negative electrode plate 20 and the positive electrode plate 30. Specifically, in the opposed capacity ratio prediction process, the ratio of the positive electrode capacity predicted in step S13 to the negative electrode capacity predicted in step S15 is predicted as the opposed capacity ratio of the lithium-ion secondary battery 10.

[0051] When the opposed capacity ratio prediction process is completed, in step S18, the cell capacity measurement process is performed. The cell capacity measurement process is a process of measuring the cell capacity of the lithium-ion secondary battery 10 which is the actual inspection target.

[0052] When the cell capacity measurement process is completed, in step S19, it is determined whether the measured cell capacity is within the allowable range. The allowable range is calculated based on the cell capacity of the lithium-ion secondary battery 10 predicted in step S16. The cell capacity measurement process is performed, for example, at room temperature of about 20°C. In the cell capacity measurement process, a plurality of lithium-ion secondary batteries 10 may be constrained.

[0053] If it is determined that the measured cell capacity is within the allowable range, it is determined that the lithium-ion secondary battery 10 is normal as the inspection result of the cell capacity inspection, and the process proceeds to step S20. If it is determined that the measured cell capacity is not within the allowable range, it is determined that the lithium-ion secondary battery 10 is abnormal as the inspection result of the cell capacity inspection, and in step S26, it is determined that the lithium-ion secondary battery 10 is abnormal. Thus, the cell capacity inspection is performed. In the present embodiment, steps S19, S25, and S26 correspond to an example of the cell capacity determination process.

[0054] When it is determined that the cell capacity is within the allowable range, in step S20, the first measurement process is performed. In the first measurement process, the first open circuit voltage OCV (Open Circuit Voltage) 1 of the lithium-ion secondary battery 10 is measured. That is, the first measurement process is a process of measuring the voltage value of the lithium-ion secondary battery 10. The processes after the first measurement process are performed at room temperature of about 20°C, for example. In the processes after the first measurement process, a plurality of lithium-ion secondary batteries 10 may be restrained.

[0055] When the first measurement process is completed, in step S21, it is determined whether a specified time has elapsed since the completion of the first measurement process. In the present embodiment, 72 hours is defined as the specified time, but it is not limited thereto. Until the specified time has elapsed since the completion of the first measurement process, the process does not proceed to step S22, and when the specified time has elapsed since the completion of the first measurement process, the process proceeds to step S22.

[0056] When the specified time has elapsed since the completion of the first measurement process, in step S22, the second measurement process is performed. In the second measurement process, the second open circuit voltage OCV2 of the lithium-ion secondary battery 10 is measured. That is, the second measurement process is a process of measuring the voltage value of the lithium-ion secondary battery 10 when the specified time has elapsed since the first measurement process was performed.

[0057] When the second measurement process is completed, in step S23, a correction process is performed. In the correction process, based on the difference between the first open-circuit voltage OCV1 and the second open-circuit voltage OCV2, and a specified time, the voltage drop value per unit time is calculated. A correction value corresponding to the predicted counter capacitance ratio predicted in step S17 is calculated. By calculating the calculated voltage drop value per unit time and the correction value, the voltage drop value per unit time is corrected. Specifically, the voltage drop value per unit time is corrected by adding the correction value to the calculated voltage drop value per unit time. Also, the correction value includes a positive correction value and a negative correction value. Thus, the correction process is a process of calculating the voltage drop value per unit time based on the voltage values measured in steps S20 and S22, and the correction value corresponding to the predicted counter capacitance ratio predicted in step S17, and correcting the voltage drop value per unit time.

[0058] When the correction process is completed, in step S24, it is determined whether or not the corrected voltage drop value per unit time is less than or equal to a threshold value. When it is determined that the voltage drop value per unit time is less than or equal to the threshold value, in step S25, it is determined that the lithium-ion secondary battery 10 is normal. When it is determined that the voltage drop value per unit time is not less than or equal to the threshold value, in step S26, it is determined that the lithium-ion secondary battery 10 is abnormal. Thus, the self-discharge inspection is performed. In the present embodiment, steps S19, S25, and S26 correspond to an example of the self-discharge determination process.

[0059] <Counter capacitance ratio and correction value> Here, the relationship between the counter capacitance ratio and the correction value will be described. As shown in FIG. 6, a reference counter capacitance ratio R0 is determined. The reference counter capacitance ratio R0 is the counter capacitance ratio at which the correction value for the calculated voltage drop value per unit time becomes 0. Thus, when the reference counter capacitance ratio R0 is predicted in step S17, the correction value corresponding to the reference counter capacitance ratio R0 becomes 0, and the calculated voltage drop value per unit time itself becomes the determination target of the self-discharge inspection.

[0060] When the opposing capacitance ratio is larger than the reference opposing capacitance ratio R0, a positive correction value is calculated. To give a specific example, when a first opposing capacitance ratio R1 larger than the reference opposing capacitance ratio R0 is predicted, a first correction value CV1 is calculated as the correction value. The first correction value CV1 is a positive correction value. Thus, when the first opposing capacitance ratio R1 is predicted in step S17, the correction value corresponding to the first opposing capacitance ratio R1 becomes a positive correction value. As a result, the calculation result obtained by adding the first correction value CV1 to the calculated voltage drop value per unit time becomes the corrected voltage drop value per unit time, which is the subject of determination in the self-discharge inspection. In this way, when the opposing capacitance ratio predicted in step S17 is the first opposing capacitance ratio R1 larger than the reference opposing capacitance ratio R0, the voltage drop value per unit time is corrected so as to increase.

[0061] When the opposing capacitance ratio is smaller than the reference opposing capacitance ratio R0, a negative correction value is calculated. To give a specific example, when a second opposing capacitance ratio R2 smaller than the reference opposing capacitance ratio R0 is predicted, a second correction value CV2 is calculated as the correction value. The second correction value CV2 is a negative correction value. Thus, when the second opposing capacitance ratio R2 is predicted in step S17, the correction value corresponding to the second opposing capacitance ratio R2 becomes a negative correction value. As a result, the calculation result obtained by adding the second correction value CV2 to the calculated voltage drop value per unit time becomes the corrected voltage drop value per unit time, which is the subject of determination in the self-discharge inspection. In this way, when the opposing capacitance ratio predicted in step S17 is the second opposing capacitance ratio R2 smaller than the reference opposing capacitance ratio R0, the voltage drop value per unit time is corrected so as to decrease. Note that in the present embodiment, the reference opposing capacitance ratio R0 is assumed to be 1.72, the first opposing capacitance ratio R1 is 1.86, and the second opposing capacitance ratio R2 is 1.65, but it is not limited thereto.

[0062] <SOC, Opposing Capacitance Ratio, Open Circuit Voltage OCV, and Negative Electrode Potential Vnp> Next, with reference to FIGS. 7 to 10, the relationships among the SOC, the counter capacity ratio, the open circuit voltage OCV, and the negative electrode potential Vnp will be described. In FIGS. 7 to 9, the open circuit voltage OCV and the negative electrode potential Vnp when the counter capacity ratio is the reference counter capacity ratio R0 are shown by solid lines. In FIGS. 7 to 9, the open circuit voltage OCV and the negative electrode potential Vnp when the counter capacity ratio is the first counter capacity ratio R1 are shown by dashed lines. In FIGS. 7 to 9, the open circuit voltage OCV and the negative electrode potential Vnp when the counter capacity ratio is the second counter capacity ratio R2 are shown by two-dot chain lines.

[0063] As shown in FIG. 7, when the SOC decreases, the open circuit voltage OCV of the lithium ion secondary battery 10 decreases. When the SOC increases, the open circuit voltage OCV of the lithium ion secondary battery 10 increases. When the SOC decreases, the negative electrode potential Vnp of the lithium ion secondary battery 10 increases. When the SOC increases, the negative electrode potential Vnp of the lithium ion secondary battery 10 decreases.

[0064] In particular, as shown in FIG. 8, at SOC 80% to 90% that can be obtained in the self-discharge test, the negative electrode potential Vnp varies according to the counter capacity ratio. Specifically, at SOC 80% to 90% that can be obtained in the self-discharge test, the negative electrode potential Vnp drops more rapidly when the counter capacity ratio is the reference counter capacity ratio R0 than when it is the first counter capacity ratio R1. Also, at SOC 80% to 90% that can be obtained in the self-discharge test, the negative electrode potential Vnp drops more rapidly when the counter capacity ratio is the second counter capacity ratio R2 than when it is the reference counter capacity ratio R0.

[0065] As shown in FIG. 9, at SOC 80% to 90% that can be obtained in the self-discharge test, the voltage drop value of the open circuit voltage OCV per SOC varies according to the counter capacity ratio. This is due to the fact that at SOC 80% to 90% that can be obtained in the self-discharge test, the negative electrode potential Vnp varies according to the counter capacity ratio.

[0066] Specifically, as shown in FIGS. 9 and 10, at SOC 80% - 90% that can be obtained in the self-discharge test, the voltage drop value of the open circuit voltage OCV per SOC is smaller when the counter capacitance ratio is the first counter capacitance ratio R1 than when it is the reference counter capacitance ratio R0. At SOC 80% - 90% that can be obtained in the self-discharge test, the voltage drop value of the open circuit voltage OCV per SOC is larger when the counter capacitance ratio is the second counter capacitance ratio R2 than when the counter capacitance ratio is the reference counter capacitance ratio R0.

[0067] <Operation of this Embodiment> The operation of this embodiment will be described. First, the lithium-ion secondary battery 10 is manufactured. In particular, in the source process of manufacturing the negative electrode plate 20 and the positive electrode plate 30, for example, the material properties of the positive electrode, the basis weight of the positive electrode, the coating area of the positive electrode, the material properties of the negative electrode, the basis weight of the negative electrode, and the coating area of the negative electrode can be specified. Also, in the liquid injection and sealing process, the amount of the electrolyte can be specified by the amount of the non-aqueous electrolyte 18 injected into the lid 12.

[0068] When the manufacturing of the lithium-ion secondary battery 10 is completed, the first charge is performed on the lithium-ion secondary battery 10 in the charging process. Then, in the high-temperature aging process, the lithium-ion secondary battery 10 is stored in a high-temperature environment. Thereby, as the inspection conditions of the lithium-ion secondary battery 10, the first charge capacity and the high-temperature aging conditions can be specified.

[0069] Next, based on the manufacturing conditions of the lithium-ion secondary battery 10 and the inspection conditions of the lithium-ion secondary battery 10, the positive electrode capacity, the negative electrode capacity, and the irreversible capacity of the lithium-ion secondary battery 10 are predicted. Then, based on the predicted positive electrode capacity, negative electrode capacity, and irreversible capacity of the lithium-ion secondary battery 10, the cell capacity and the counter capacitance ratio of the lithium-ion secondary battery 10 are predicted.

[0070] As for the cell capacity inspection, it is determined whether the measured cell capacity is within the allowable range based on the predicted cell capacity. And when it is determined that the measured cell capacity is not within the allowable range, it is determined that the lithium-ion secondary battery 10 is abnormal as the cell capacity inspection. When it is determined that the measured cell capacity is within the allowable range, it is determined that the lithium-ion secondary battery 10 is normal as the cell capacity inspection.

[0071] As for the self-discharge inspection, the voltage drop value per unit time measured and the correction value corresponding to the predicted counter capacity ratio are calculated, and thereby the voltage drop value per unit time measured is corrected. It is determined whether the corrected voltage drop value per unit time is less than or equal to the threshold value. And when it is determined that the corrected voltage drop value per unit time is not less than or equal to the threshold value, it is determined that the lithium-ion secondary battery 10 is abnormal as the self-discharge inspection. When it is determined that the corrected voltage drop value per unit time is less than or equal to the threshold value, it is determined that the lithium-ion secondary battery 10 is normal as the self-discharge inspection.

[0072] <Advantages of the present embodiment> The advantages of the present embodiment will be described. (1) According to the inspection method of the lithium-ion secondary battery 10 of the present embodiment, based on the manufacturing conditions of the lithium-ion secondary battery 10, the positive electrode capacity and the negative electrode capacity of the lithium-ion secondary battery 10 can be predicted. Furthermore, based on the predicted positive electrode capacity and negative electrode capacity of the lithium-ion secondary battery 10, the counter capacity ratio of the lithium-ion secondary battery 10 can be predicted. And the voltage drop value per unit time based on the measured voltage value and the correction value corresponding to the predicted counter capacity ratio are calculated, and the voltage drop value per unit time can be corrected. Thereby, it is possible to determine whether the lithium-ion secondary battery 10 is normal with respect to the voltage drop value per unit time corrected according to the counter capacity ratio of the lithium-ion secondary battery 10, and the inspection accuracy can be improved.

[0073] (2) When the counter capacitance ratio is large, the voltage drop per SOC tends to be smaller than when the counter capacitance ratio is small. Therefore, according to the inspection method of the lithium-ion secondary battery 10 of the present embodiment, when the predicted counter capacitance ratio is the first counter capacitance ratio R1 greater than the reference counter capacitance ratio R0, it is possible to correct so as to increase the voltage drop per unit time. On the other hand, when the predicted counter capacitance ratio is the second counter capacitance ratio R2 smaller than the reference counter capacitance ratio R0, it is possible to correct so as to decrease the voltage drop per unit time. Thereby, it is possible to determine whether the lithium-ion secondary battery 10 is normal with respect to the voltage drop per unit time corrected according to the counter capacitance ratio of the lithium-ion secondary battery 10, and the inspection accuracy can be improved.

[0074] (3) According to the inspection method of the lithium-ion secondary battery 10 of the present embodiment, the irreversible capacity of the lithium-ion secondary battery 10 can be predicted based on the manufacturing conditions of the lithium-ion secondary battery 10. Furthermore, based on the predicted positive electrode capacity and irreversible capacity of the lithium-ion secondary battery 10, the cell capacity of the lithium-ion secondary battery 10 can be predicted. When the measured cell capacity is within the allowable range based on the predicted cell capacity, it can be determined that the lithium-ion secondary battery 10 is normal. Thereby, both the self-discharge inspection and the cell capacity inspection can be performed using the predicted positive electrode capacity.

[0075] (4) As the manufacturing conditions of the lithium-ion secondary battery 10, the positive electrode capacity of the lithium-ion secondary battery 10 can be predicted based on the electrode conditions of the positive electrode. As the manufacturing conditions of the lithium-ion secondary battery 10, the negative electrode capacity of the lithium-ion secondary battery 10 can be predicted based on the electrode conditions of the negative electrode. Thereby, the voltage drop per unit time can be corrected according to the electrode conditions of the positive electrode and the electrode conditions of the negative electrode.

[0076] [Modified Example] This embodiment can be implemented with the following modifications. This embodiment and the following modification examples can be implemented in combination with each other within a technically consistent range.

[0077] ○ In this embodiment, for example, on the premise that the measured cell capacity of the lithium-ion secondary battery 10 is within the allowable range, a correction value corresponding to the comparison result with the predicted cell capacity of the lithium-ion secondary battery 10 may be calculated. The comparison result between the measured cell capacity of the lithium-ion secondary battery 10 and the predicted cell capacity of the lithium-ion secondary battery 10 may be the difference between the measured cell capacity of the lithium-ion secondary battery 10 and the predicted cell capacity of the lithium-ion secondary battery 10. The comparison result between the measured cell capacity of the lithium-ion secondary battery 10 and the predicted cell capacity of the lithium-ion secondary battery 10 may be the ratio between the measured cell capacity of the lithium-ion secondary battery 10 and the predicted cell capacity of the lithium-ion secondary battery 10. For example, when the measured cell capacity is larger than the predicted cell capacity, considering that the actual positive electrode capacity is larger than the predicted positive electrode capacity and the actual counter capacity ratio is smaller than the predicted counter capacity ratio, the correction value may be decreased. For example, when the measured cell capacity is smaller than the predicted cell capacity, considering that the actual positive electrode capacity is smaller than the predicted positive electrode capacity and the actual counter capacity ratio is larger than the predicted counter capacity ratio, the correction value may be increased. Thereby, the self-discharge inspection can be performed in consideration of the comparison result between the actual cell capacity and the predicted cell capacity, and the inspection accuracy can be improved.

[0078] ○ In this embodiment, as manufacturing conditions of the lithium-ion secondary battery 10, for example, as parameters for predicting the positive electrode capacity, there may be other parameters such as the thickness of the electrode body 15 wound in the winding process. Also, for example, at least any one of a plurality of parameters for predicting the positive electrode capacity, irreversible capacity, and negative electrode capacity in this embodiment may be absent.

[0079] ○ In the present embodiment, for example, the voltage drop value per unit time may be multiplied by a correction value. In this way, the voltage drop value per unit time may be corrected by the operation of the voltage drop value per unit time and the correction value. That is, when the predicted counter capacitance ratio is large, the voltage drop value per unit time may be corrected to increase, and when the predicted counter capacitance ratio is small, the voltage drop value per unit time may be corrected to decrease, and the calculation method is not limited.

[0080] ○ In the present embodiment, the voltage drop value per unit time is used as the determination target. However, for example, if the specified time from the first measurement step of measuring the first open circuit voltage OCV1 to the second measurement step of measuring the second open circuit voltage OCV2 is constant, the voltage drop value itself may be used as the determination target.

[0081] ○ In the present embodiment, based on the inspection conditions of the lithium ion secondary battery 10 such as the initial charge capacity, for example, the positive electrode capacity of the lithium ion secondary battery 10 may not be predicted. ○ In the present embodiment, based on the inspection conditions of the lithium ion secondary battery 10 such as the high temperature aging conditions, for example, the irreversible capacity of the lithium ion secondary battery 10 may not be predicted.

[0082] ○ In the present embodiment, in the positive electrode capacity prediction step, based on at least one of the material physical properties of the positive electrode, the weight per unit area of the positive electrode, and the coating area of the positive electrode as the manufacturing conditions of the lithium ion secondary battery 10, the positive electrode capacity of the lithium ion secondary battery 10 may be predicted.

[0083] ○ In the present embodiment, in the negative electrode capacity prediction step, based on at least one of the weight per unit area of the negative electrode and the coating area of the negative electrode as the manufacturing conditions of the lithium ion secondary battery 10, the negative electrode capacity of the lithium ion secondary battery 10 may be predicted.

[0084] ○ In this embodiment, in the irreversible capacity prediction step, as manufacturing conditions of the lithium ion secondary battery 10, the irreversible capacity of the lithium ion secondary battery 10 may be predicted based on at least any one of the material physical properties of the negative electrode, the basis weight of the negative electrode, the coating area of the negative electrode, and the amount of the electrolytic solution.

[0085] ○ In this embodiment, the first measurement step and the second measurement step are performed when the SOC of the lithium ion secondary battery 10 is 80% to 90%, but are not limited thereto. The first measurement step and the second measurement step may be performed, for example, when the SOC of the lithium ion secondary battery 10 is 80% to 100%, or may be performed, for example, when the SOC of the lithium ion secondary battery 10 is 90% to 100%.

[0086] ○ In this embodiment, the flowchart shown in FIG. 5 is an example, and those skilled in the art can add, delete, change, and perform the procedures in a different order. In particular, at least any one of steps S13 to S17 in FIG. 5 may be performed before steps S11 and S12, or may be performed during the execution of steps S11 and S12.

[0087] ○ In this embodiment, a cell capacity inspection may be performed after the self-discharge inspection. ○ In this embodiment, a cell capacity inspection may not be performed in accordance with the self-discharge inspection. In this case, steps S14, S16, S18, and S19 in FIG. 5 may not be performed.

[0088] ○ In this embodiment, the present invention has been described by taking the lithium ion secondary battery 10 as an example, but it can also be applied to other non-aqueous electrolyte secondary batteries. ○ In this embodiment, the in-vehicle thin plate-shaped lithium ion secondary battery 10 has been exemplified, but it can also be applied to cylindrical batteries and the like. Further, it is not limited to in-vehicle use, and can also be applied to marine, aircraft, and stationary batteries.

[0089] ○ Needless to say, the present invention can be implemented by those skilled in the art by adding, deleting, changing, and performing the configuration in a different order without departing from the scope of the claims.

Explanation of Symbols

[0090] CV1…First correction value CV2…Second correction value D…Thickness direction OCV…Open-circuit voltage OCV1…First open-circuit voltage OCV2…Second open-circuit voltage R0…Reference facing capacitance ratio R1…First facing capacitance ratio R2…Second facing capacitance ratio Vnp…Negative electrode potential W…Width direction Z…Length direction 10…Lithium-ion secondary battery 11…Battery case 12…Cover 13…Negative electrode external terminal 14…Positive electrode external terminal 15…Electrode body 16…Negative electrode current collector 17…Positive electrode current collector 18…Non-aqueous electrolyte 20…Negative electrode plate 21…Negative electrode substrate 22…Negative electrode composite layer 23…Negative electrode connection part 30…Positive electrode plate 31…Positive electrode substrate 32…Positive electrode composite layer 33…Positive electrode connection part 40…Separator

Claims

1. A method for inspecting a non-aqueous electrolyte secondary battery including an electrode body including a positive electrode, a negative electrode, and a separator, a non-aqueous electrolyte, and a battery case housing the electrode body and the non-aqueous electrolyte, comprising: A positive electrode capacity prediction step of predicting the positive electrode capacity of the non-aqueous electrolyte secondary battery based on the manufacturing conditions of the non-aqueous electrolyte secondary battery; A negative electrode capacity prediction step of predicting the negative electrode capacity of the non-aqueous electrolyte secondary battery based on the manufacturing conditions of the non-aqueous electrolyte secondary battery; A counter capacity ratio prediction step of predicting a counter capacity ratio based on the positive electrode capacity predicted in the positive electrode capacity prediction step and the negative electrode capacity predicted in the negative electrode capacity prediction step; A first measurement step of measuring the voltage value of the non-aqueous electrolyte secondary battery; A second measurement step of measuring the voltage value of the non-aqueous electrolyte secondary battery when a specified time has elapsed after the first measurement step is performed; A correction step of calculating a voltage drop value based on the voltage value measured in the first measurement step and the voltage value measured in the second measurement step, and a correction value corresponding to the counter capacity ratio predicted in the counter capacity ratio prediction step, and correcting the voltage drop value; An self-discharge determination step of determining that the non-aqueous electrolyte secondary battery is normal when the voltage drop value corrected in the correction step is equal to or less than a threshold value. A method for inspecting a non-aqueous electrolyte secondary battery.

2. In the method for inspecting a non-aqueous electrolyte secondary battery according to claim 1, In the correction step, when the counter capacity ratio predicted in the counter capacity ratio prediction step is a first counter capacity ratio greater than a reference counter capacity ratio, the voltage drop value is corrected so as to increase, while when the counter capacity ratio predicted in the counter capacity ratio prediction step is a second counter capacity ratio smaller than the reference counter capacity ratio, the voltage drop value is corrected so as to decrease. A method for inspecting a non-aqueous electrolyte secondary battery.

3. In the method for inspecting a non-aqueous electrolyte secondary battery according to claim 1 or claim 2, An irreversible capacity prediction step of predicting the irreversible capacity of a non-aqueous electrolyte secondary battery based on the manufacturing conditions of the non-aqueous electrolyte secondary battery, A cell capacity prediction step of predicting the cell capacity of a non-aqueous electrolyte secondary battery based on the positive electrode capacity predicted in the positive electrode capacity prediction step and the irreversible capacity predicted in the irreversible capacity prediction step, A cell capacity measurement step of measuring the cell capacity of a non-aqueous electrolyte secondary battery, A cell capacity determination step of determining that the non-aqueous electrolyte secondary battery is normal when the cell capacity measured in the cell capacity measurement step is within an allowable range based on the cell capacity predicted in the cell capacity prediction step, including: A method for inspecting a non-aqueous electrolyte secondary battery.

4. In the method for inspecting a non-aqueous electrolyte secondary battery according to any one of Claims 1 to 3, The positive electrode capacity prediction step is a step of predicting the positive electrode capacity of a non-aqueous electrolyte secondary battery based on the electrode conditions of the positive electrode as the manufacturing conditions of the non-aqueous electrolyte secondary battery, The negative electrode capacity prediction step is a step of predicting the negative electrode capacity of a non-aqueous electrolyte secondary battery based on the electrode conditions of the negative electrode as the manufacturing conditions of the non-aqueous electrolyte secondary battery. A method for inspecting a non-aqueous electrolyte secondary battery.

5. In the method for inspecting a non-aqueous electrolyte secondary battery according to Claim 4, The positive electrode capacity prediction step is a step of predicting the positive electrode capacity of a non-aqueous electrolyte secondary battery based on at least any one of the material physical properties of the positive electrode, the weight per unit area of the positive electrode, and the coating area of the positive electrode as the electrode conditions of the positive electrode, The negative electrode capacity prediction step is a step of predicting the negative electrode capacity of a non-aqueous electrolyte secondary battery based on at least any one of the weight per unit area of the negative electrode and the coating area of the negative electrode as the electrode conditions of the negative electrode. A method for inspecting a non-aqueous electrolyte secondary battery.

6. In the method for inspecting a non-aqueous electrolyte secondary battery according to any one of Claims 1 to 5, A method for inspecting a non-aqueous electrolyte secondary battery, including a high-temperature aging process of storing a charged non-aqueous electrolyte secondary battery in a high-temperature environment. A method for inspecting a non-aqueous electrolyte secondary battery.

7. In the method for inspecting a non-aqueous electrolyte secondary battery according to any one of Claims 1 to 6, the first measurement step and the second measurement step are performed when the state of charge (SOC) of the non-aqueous electrolyte secondary battery is 80% to 90%. A method for inspecting a non-aqueous electrolyte secondary battery.

Images