JP2019160775A - Electrode plate inspection equipment and electrode plate inspection method - Google Patents

Abstract

To provide electrode plate inspection equipment and an electrode plate inspection method capable of inspecting detailed state of the electrode plate of a secondary cell more accurately.SOLUTION: Electrode plate inspection equipment includes a placement table 108 for holding an electrode plate 100 of a secondary cell in electrolyte 106, a probe 11 including a counter electrode 114 in the electrolyte in a container having a measurement window opening toward the electrode plate 100, a resistance component measurement unit 13 connected between the electrode plate 100 and the counter electrode 114 and measuring the internal resistance value (DC-IR) for the DC current therebetween, and a move part for moving the probe 11 relatively to the electrode plate 100. The move part moves the probe 11 sequentially to different measuring points Tg. Since resistance component measurement unit 13 measures DC-IR for every measuring points Tg, the amount of electricity is returned to the original amount of electricity before charge by discharging after charge, or returned to the original amount of electricity before discharge by charging after discharge.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an electrode plate inspection apparatus and an electrode plate inspection method for inspecting an electrode plate of a battery.

  A lithium ion secondary battery, which is one of non-aqueous electrolyte secondary batteries, has a high energy density and a high capacity, and is therefore used as a power source for driving an electric vehicle (EV), a hybrid vehicle (HV), etc. It has been. A lithium ion secondary battery has an electrode body obtained by winding or laminating a positive electrode plate having an active material layer on both surfaces of an electrode core and a negative electrode plate with a separator interposed therebetween. One of such secondary battery inspection techniques is an inspection based on complex impedance with respect to an electrode plate. For example, Patent Document 1 describes an example of a technique for measuring complex impedance.

  The technique for inspecting an electrode plate described in Patent Document 1 includes a measurement unit that is connected to a counter electrode disposed in an electrolytic solution and that acts on a part of an electrode active material layer that is opposed via the electrolytic solution. Prepare a probe. Moreover, the measurement part of a probe is made to act on a part of electrode active material layer which opposes, and the counter electrode in a probe and the to-be-measured part of an electrode active material layer are electrically connected through electrolyte solution. Further, the impedance is measured between the electrically connected counter electrode and the part to be measured, and the resistance of the electrode is calculated based on the measurement of the impedance. And the area of the counter electrode in a probe is 100 times or more larger than the operation area of the measurement part of this probe.

JP 2014-25850 A

By the way, in recent years, a technique capable of more accurately inspecting the detailed state of the electrode plate of the secondary battery is required so that the performance of the secondary battery is sufficiently exhibited.
Moreover, such a subject is the same not only in a secondary battery but also in a battery including a primary battery.

  The present invention has been made in view of such circumstances, and an object thereof is to provide an electrode plate inspection apparatus and an electrode plate inspection method capable of more accurately inspecting the detailed state of a battery electrode plate. There is to do.

  An electrode plate inspection apparatus that solves the above-described problems is provided in an electrolyte solution in a container having an electrode plate holding portion that holds an electrode plate of a secondary battery in the electrolyte solution, and a measurement window that opens toward the electrode plate. A probe having a counter electrode, a measuring unit connected to the electrode plate and the counter electrode to measure an internal resistance value (DC-IR) with respect to a direct current between the electrode plate and the counter electrode, and the probe to the electrode A moving unit that moves the probe relative to the plate, the moving unit sequentially moves the probe to different measurement points, and the measuring unit measures the internal resistance value for each measurement point. After being performed, discharging is performed to return to the amount of electricity before performing the charging, or after discharging is performed, charging is performed to return to the amount of electricity before performing the discharging.

  An electrode plate inspection method that solves the above problems is a method of inspecting an electrode plate with an electrode plate inspection apparatus, and is directed to an electrode plate holding portion that holds an electrode plate of a secondary battery in an electrolyte, and to the electrode plate A probe having a counter electrode in an electrolyte solution in a container having a measurement window opened, and an internal resistance value (DC) between the electrode plate and the counter electrode connected to the electrode plate and the counter electrode. -IR) is used in an electrode plate inspection apparatus including a measurement unit that measures (IR) and a moving unit that moves the probe relative to the electrode plate, and the moving unit sequentially moves the probe to different measurement points. In order to measure the internal resistance value at each measurement point, the moving step and the step of discharging after charging and returning to the amount of electricity before the charging or discharging were performed. The battery is charged before being discharged. And a measuring step having a step of returning to the quantity.

  According to such a configuration or method, the internal resistance value (DC-IR) of the measurement point of the electrode plate can be measured, and the measurement point after the measurement can be returned to the charged state before the measurement. By returning to the original state, the DC-IR at other measurement points can be appropriately measured, and the distribution of DC-IR can be obtained for the entire electrode plate. Therefore, the detailed state of the electrode plate of the secondary battery can be inspected more accurately. The internal resistance value may be measured during charging or during discharging.

  As a preferred configuration, the measurement unit acquires DC currents at different measurement points, respectively, and determines a state relating to the current of the electrode plate by comparing the DC currents acquired between the different measurement points. Is further provided.

  According to such a structure, the state regarding the electric current in each measurement point of an electrode plate can be determined by comparing the direct current of a different measurement point. That is, it is possible to determine the quality distribution with respect to the current in the electrode plate.

  As a preferred configuration, the probe can select an opening area of the measurement window from a plurality of areas, and the measurement unit can measure the internal resistance value at the measurement point by opening the measurement window. For each area.

  According to such a configuration, the influence of the opening area of the measurement window (area of the measurement window) is reflected, and the DC-IR for the measurement point can be measured. As the area of the measurement window increases, the effect of deep depth is included. Therefore, if the area of the measurement window is large, a depth characteristic that cannot be obtained by impedance measurement that measures a state in a range close to the surface can be obtained. Moreover, the depth in which a malfunctioning part exists can also be acquired by measuring in several areas.

As a preferred configuration, the probe has a variable opening area of the measurement window.
According to such a configuration, the open area of the measurement window can be easily changed. Measurement becomes easy.

  As a preferred configuration, when discharging after performing the charging, the charging voltage applied to the measurement point is different from the discharging voltage, or when performing charging after performing the discharging, the discharging applied to the measuring point. Different voltage and charging voltage.

According to such a configuration, the charging voltage and discharging voltage can be set to a voltage suitable for DC-IR measurement, or can be set to a voltage suitable for returning the amount of electricity.
As a preferred configuration, when discharging is performed after the charging, the voltage at the measurement point is the same voltage before and after the charging, or the discharging is performed. When charging is performed later, the amount of electricity to be charged and the amount of electricity to be discharged are adjusted so that the voltage at the measurement point is the same before and after the discharge.

  According to such a configuration, by adjusting the charging voltage and the discharging voltage with respect to the measurement point, the amount of electricity is returned by discharging after charging, or the amount of electricity is returned by charging after discharging. become.

  As a preferred configuration, the measurement unit also measures complex impedance, a fitting unit for fitting the complex impedance to a characteristic model of a secondary battery, and DC-IR based on the characteristic model of the electrode plate. And a calculation unit that calculates, when the fitting unit fits the complex impedance of the measurement point to the characteristic model of the electrode plate, a measurement adjacent to the measurement point to an initial value given to the characteristic model of the electrode plate A fitting result for a point is adopted, and the calculation unit calculates a DC-IR based on the fitting result, and compares the measured DC-IR with the calculated DC-IR.

  According to such a configuration, the battery model based on the distribution of complex impedance acquired with respect to the electrode plate can be compared with the measurement result. Moreover, the deterioration state of an electrode plate can be determined based on such a comparison result.

  An electrode plate inspection apparatus that solves the above problems includes an electrode plate holding unit that holds an electrode plate of a secondary battery in an electrolyte solution, and a charge amount of the electrode plate is adjusted to a predetermined charge amount by discharging or charging. A first adjustment unit, a probe having a counter electrode in an electrolyte in a container having a measurement window opened toward the electrode plate, and the probe are sequentially arranged at different measurement points on the electrode plate. It is connected to the moving part that moves relative to the electrode plate, the electrode plate and the counter electrode, and for each measurement point, while maintaining the charge electricity amount of the electrode plate, an upper limit value and a lower limit value An equilibrium state impedance acquisition unit that acquires an impedance in an equilibrium state corresponding to the measurement frequency by applying an alternating current having a measurement frequency that changes a predetermined frequency range to be divided to the electrode plate, the electrode plate, and the counter electrode When Charging electricity that is connected and changed by applying the alternating current having the measurement frequency to the electrode plate while changing the amount of charge of the electrode plate by charging or discharging a direct current at each measurement point. A transient state impedance acquisition unit that acquires the impedance of the transient state corresponding to the amount; and a second adjustment that adjusts the charged amount of electricity at the measurement point to the amount of charged charge before acquiring the impedance of the transient state by discharging or charging A unique component calculation unit that calculates a transient state specific component based on an electrode plate state calculated based on the impedance in the transient state and an electrode plate state calculated based on the impedance in the equilibrium state. Prepare.

  An electrode plate inspection method that solves the above problems is a method of inspecting an electrode plate with an electrode plate inspection device, the electrode plate holding portion for holding the electrode plate of a secondary battery in an electrolyte, and charging of the electrode plate A first adjusting unit that adjusts the amount of electricity to a predetermined amount of charged electricity by discharging or charging; a probe having a counter electrode in an electrolyte in a container having a measurement window that opens toward the electrode plate; A moving part that moves relative to the electrode plate so that probes are sequentially arranged at different measurement points of the electrode plate, and an alternating current between the electrode plate and the counter electrode connected to the electrode plate and the counter electrode A measurement unit that measures impedance with respect to the electrode plate, and is divided into an upper limit value and a lower limit value while maintaining the charge electricity amount of the electrode plate for each measurement point in the measurement unit. Change the predetermined frequency range An equilibrium state impedance acquisition step of acquiring an impedance in an equilibrium state corresponding to the measurement frequency by applying an alternating current having a measurement frequency to the electrode plate, and at the measurement unit, for each measurement point, Transient state impedance for obtaining a transient state impedance corresponding to the amount of charged charge that changes by applying the alternating current having the measurement frequency to the electrode plate while changing the amount of charged electricity by charging or discharging a direct current. Based on the acquisition step, the adjustment step of adjusting the charge amount of electricity at the measurement point to the charge amount before acquiring the impedance of the transient state by discharging or charging in the second adjustment unit, and the impedance of the transient state And the electrode plate state calculated based on the impedance in the equilibrium state. And a specific component calculation step of calculating a transient specific component.

  According to such a configuration or method, the transient state-specific component indicating the electrode plate state resulting from the measurement point of the electrode plate being in the transient state is calculated based on the transient state impedance and the equilibrium state impedance. In addition, the measurement point after measurement can be returned to the state of charge before measurement. By returning to the original state, the transient state-specific component at other measurement points can be appropriately measured, and the distribution of the transient state-specific component can be obtained for the entire electrode plate. Therefore, the electrode plate state in the transient state of the electrode plate of the secondary battery can be measured based on the impedance measurement. In addition, the measurement of a transient state specific component may be performed at the time of charge, and may be performed at the time of discharge.

As a preferable configuration, the opening diameter of the measurement window of the probe is not more than twice the particle diameter of the active material particles of the electrode plate.
According to such a configuration, by reducing the opening diameter of the probe to the particle size level of the active material particles, the behavior of the active material particles in one particle, that is, the electrochemical phenomenon due to the transient characteristics in the active material itself is measured. Will be able to.

  As a preferred configuration, the probe is a first probe, and includes a second probe having an area twice or more that of the first probe, and the electrode plate is deteriorated by measurement using the second probe. The portion determined to be measured with the first probe.

  According to such a configuration, the measurement range narrowed down by the second probe having the large measurement window area can be measured by the first probe having the small measurement window area, and the first probe having the small measurement area can be measured. It becomes possible to quickly perform the measurement by the necessary place.

As a preferred configuration, in the transient state impedance acquisition unit, the direct current is a rectangular wave.
According to such a configuration, it is easy to calculate a change in the amount of electricity charged in the electrode plate by making the direct current a rectangular wave.

As a preferred configuration, there is provided a determination step of determining the electrode plate state of the electrode plate by comparing the transient state-specific component with a determination threshold that is a value capable of determining deterioration of the electrode plate.
According to such a configuration, the battery state can be determined by comparing the transient state-specific component with the determination threshold that can measure the deterioration of the electrode plate.

  As a preferred configuration, the transient state impedance acquisition unit uses the lower limit value and the upper limit value that divide the predetermined frequency range as a starting point and the other value as an end point. To the end point and return to the start point value in response to reaching the end point value, changing the start point to the end point in a time of 10 seconds or less, and the end point To the start point in 10 seconds or less.

  According to such a configuration, since the measurement frequency changes from the start point (upper limit value) to the end point (lower limit value), it is easy to grasp continuous frequency characteristics. Moreover, it is easy to generate and measure as a measurement frequency. Further, the impedance in the transient state can be measured by repeating the measurement frequency at an interval where the electrode plate is shorter than the response period in the transient state, for example, 10 seconds.

  As a preferred configuration, the specific component calculation unit fits the impedance in the transient state to an equivalent circuit to obtain the equivalent circuit in the transient state corresponding to the electrode plate in the transient state, and the impedance in the balanced state To the equivalent circuit to obtain the equivalent circuit in the equilibrium state corresponding to the electrode plate in the equilibrium state, and the resistance component of the equivalent circuit in the transient state and the resistance component of the equivalent circuit in the equilibrium state The difference between the resistance components corresponding to each other is calculated as the transient state-specific component.

  According to such a configuration, the transient state specific component is calculated as a difference between resistance components corresponding to each other between the resistance component of the equivalent circuit in the transient state and the resistance component of the equivalent circuit in the equilibrium state. Thereby, the factor resulting from an equilibrium state can be reduced and the electrode plate state in a transient state can be extracted and measured.

  According to the present invention, the detailed state of the electrode plate of the battery can be inspected more accurately.

The schematic of the structure about 1st Embodiment of an electrode plate test | inspection apparatus. The graph which shows an example of the fitting of the embodiment. The flowchart which shows the procedure of the inspection process of the embodiment. The flowchart which shows the procedure of the impedance measurement of the embodiment. The flowchart which shows the procedure of the DC-IR measurement of the embodiment. The graph which shows an example of the voltage change of the DC-IR measurement of the embodiment. The schematic diagram which shows the area from which current information can be acquired with respect to the depth direction of the electrode plate of the embodiment. The schematic diagram which shows the area from which current information can be acquired with respect to the planar direction of the electrode plate of the embodiment. Explanatory drawing which shows the relationship between the malfunctioning part of the electrode plate of the embodiment, and current information. The flowchart which shows the quality determination procedure of the electrode plate of the embodiment. The schematic block diagram about 2nd Embodiment of an electrode plate test | inspection apparatus. The flowchart which shows the procedure of the inspection process of the embodiment. In the same embodiment, the flowchart which shows the measurement procedure of the electrode plate state which is an equilibrium state. In the same embodiment, it is a graph which shows an example of the electric current which measures the impedance of an equilibrium state, (a) is a figure which shows the applied electric current, (b) is a figure which shows a response voltage. The circuit diagram which shows an example of the equivalent circuit of an electrode plate in the embodiment. The flowchart which shows the measurement procedure of the electrode plate state which is a transient state in the same embodiment. In the embodiment, it is a graph which shows an example of the electric current which measures the impedance of a transient state, (a) is a figure which shows the applied electric current, (b) is a figure which shows a response voltage. The graph which shows an example of the Nyquist diagram based on the impedance of a transient state in the embodiment. The graph which shows an example of the result of having measured the impedance of the electrode plate in a transient state in the same embodiment in three dimensions. The graph which shows an example of the result of having measured the impedance of the battery in a transient state in the same embodiment in three dimensions. In the same embodiment, the graph which shows an example of the Nyquist diagram which estimated the impedance of the transient state when the electrode plate of a transient state exists in a specific charge electricity amount. 4 is a flowchart illustrating a procedure for measuring a transient state-specific component in the embodiment. The graph which shows an example which calculates a transient state specific component in the embodiment. In the same embodiment, an example of the graph which determines the deterioration state of an electrode plate based on a transient state specific component.

(First embodiment)
1st Embodiment of an electrode plate inspection apparatus and an electrode plate inspection method is described according to FIGS.

  As shown in FIG. 1, the electrode plate inspection apparatus 20 measures the complex impedance of the electrode plate 100 of the secondary battery. In the present embodiment, the secondary battery is a non-aqueous electrolyte secondary battery such as a lithium ion secondary battery. The secondary battery is a sealed battery having a rectangular parallelepiped shape, and a plurality of secondary batteries are connected by a bus bar to constitute an assembled battery. The assembled battery is mounted on an electric vehicle or a hybrid vehicle, and supplies power to an electric motor or the like.

  In complex impedance measurement, an alternating voltage (or alternating current) signal is input to an inspection object (here, an electrode plate) while changing the frequency, and the response current (or response voltage) at that time is measured. Then, the transfer function (impedance) of the electrode reaction is obtained by comparing the input sine wave with the response signal. For example, the frequency is changed from a high frequency of about 10 kHz to a low frequency of about 0.1 Hz, and the complex impedance is obtained from the response current (or response voltage) at each frequency. In general, since there is a difference in moving speed between ions and electrons, complex impedance measurement is performed using the difference in moving speed. Specifically, in the high-frequency region, electrons can move in response to changes in the direction of voltage, but ions have a slow reaction and cannot keep up. For this reason, it is possible to extract and measure only the components related to the movement of electrons from the system. Thereafter, as the frequency is further lowered, the movement of ions corresponds to a change in the direction of the AC voltage. Therefore, it is possible to measure components related to ion movement in addition to electron movement. The frequency characteristic of the complex impedance is represented in a Nyquist plot or the like, and the resistance value or the like of each component can be obtained by analyzing this.

  As shown in FIG. 2, for example, the complex impedance characteristic of the Nyquist plot can be divided into a plurality of regions corresponding to the band of the measurement frequency. Specifically, it has “region a” corresponding to the circuit resistance and “region b” corresponding to the solution resistance in response to the band changing from the high frequency side toward the low frequency side. The complex impedance characteristic corresponds to a “film resistance region c” corresponding to the complex impedance caused by the film resistance, a “reaction resistance region d” corresponding to the complex impedance caused by the reaction resistance, and a substantially linear diffusion resistance. It has “region e”. Hereinafter, the complex impedance is simply referred to as impedance.

(Electrode plate 100)
The electrode plate 100 of the secondary battery will be described with reference to FIG.
The electrode plate 100 is a positive electrode plate or a negative electrode plate in which an electrode active material layer 102 is formed on a current collector. The electrode plate 100 is formed so that the current collector 104 is exposed without the electrode active material layer 102 being provided (or removed) at the end. Each of the positive electrode plate and the negative electrode plate will be described below.

(Positive electrode)
The positive electrode includes a positive electrode current collector and a positive electrode active material layer including a positive electrode active material formed on the positive electrode current collector. In such a positive electrode, a paste-like or slurry-like composition in which a positive electrode active material and a conductive material or a binder used as necessary are dispersed in an appropriate solvent is applied to a sheet-like positive electrode current collector. It can be produced by drying the composition. For the positive electrode current collector, a conductive member made of a metal having good conductivity (for example, aluminum, nickel, titanium, stainless steel, etc.) is used. As the solvent, any of an aqueous solvent and an organic solvent can be used. For example, N-methyl-2-pyrrolidone (NMP) can be used.

(Positive electrode active material)
As the positive electrode active material, one kind or two or more kinds of various materials that can be used as the positive electrode active material of the lithium ion secondary battery can be used. For example, a lithium transition metal compound such as a layered structure or a spinel structure containing lithium and at least one transition metal element as a constituent metal element, a polyanion type (for example, olivine type) lithium transition metal compound, or the like can be used.

Preferably, general formula: LiMn _2−p M _p O ₄ (wherein p is 0 ≦ p <2, typically 0 ≦ p ≦ 1 (eg 0.2 ≦ p ≦ 0.6)) And a lithium transition metal compound (oxide) typically having a spinel structure. When p is greater than 0, M can be any metallic or non-metallic element other than Mn. A composition in which M contains at least one transition metal element (for example, one or more selected from Ti, Cr, Fe, Co, Ni, Cu, and Zn) is preferable. Specific examples include LiNi _0.5 Mn _1.5 O ₄ and LiCrMnO ₄ .

(Conductive material)
A carbon material can be used as the conductive material. Specifically, for example, selected from carbon materials such as various carbon blacks (for example, acetylene black, ketjen black), coke, activated carbon, graphite, carbon fibers (PAN-based carbon fibers, pitch-based carbon fibers), and carbon nanotubes. Can be one or more. Among them, it is preferable to use carbon black (for example, acetylene black) having a relatively small particle size and a large specific surface area.

(Binder)
As the binder, a polymer that can be dissolved or dispersed in a solvent to be used can be used. For example, in a positive electrode mixture composition using an aqueous solvent, cellulose polymers such as carboxymethylcellulose (CMC, for example, sodium salt), hydroxypropylmethylcellulose (HPMC), polyvinyl alcohol (PVA), polytetrafluoroethylene (PTFE), etc. Fluorine-based resins such as styrene-butadiene rubber (SBR) can be employed. In the positive electrode mixture composition using a non-aqueous solvent, polyvinylidene fluoride (PVdF), polyvinylidene chloride (PVdC), or the like can be employed.

  50 mass% or more is suitable for the ratio of the positive electrode active material to the whole positive electrode active material layer, and it is preferable that it is normally 70 mass% or more and 95 mass% or less. In the case of using a conductive material, the ratio of the conductive material in the entire positive electrode active material layer can be, for example, 2% by mass or more and 20% by mass or less, and preferably 2% by mass or more and 15% by mass or less. . When using a binder, the ratio of the binder to the whole positive electrode active material layer can be, for example, 0.5% by mass or more and 10% by mass or less, and usually 1% by mass or more and 5% by mass or less is preferable. .

The mass of the positive electrode active material layer provided per unit area of the positive electrode current collector can be, for example, about 5 mg / cm ^{2 to} 40 mg / cm ² (preferably 10 mg / cm ^{2 to} 20 mg / cm ² ). . The density of the positive electrode active material layer can be, for example, about 1.5 g / cm ³ or more and 4 g / cm ³ or less (preferably 1.8 g / cm ³ or more and 3 g / cm ³ or less). The thickness of is, for example, 40 μm or more (preferably 50 μm or more) and can be 100 μm or less (preferably 80 μm or less).

(Negative electrode)
The negative electrode includes a negative electrode current collector and a negative electrode active material layer including at least a negative electrode active material formed on the negative electrode current collector. Such a negative electrode includes a paste-like or slurry-like composition (a dispersion for forming a negative electrode active material layer) in which a negative electrode active material and a binder (binder) used as necessary are dispersed in a suitable solvent. ) Is applied to a sheet-like negative electrode current collector, and the composition is dried to form a negative electrode active material layer (negative electrode active material layer). As the negative electrode current collector, a conductive material made of a metal having good conductivity (for example, copper, nickel, titanium, stainless steel, etc.) is used. Moreover, as said solvent, both an aqueous solvent and an organic solvent can be used, for example, water can be used.

(Negative electrode active material)
As the negative electrode active material, one type or two or more types of materials conventionally used in lithium ion secondary batteries can be used. For example, natural graphite (graphite), artificial graphite, hard carbon (non-graphitizable carbon), soft carbon (graphitizable carbon), carbon materials such as carbon nanotubes, silicon oxide, titanium oxide, vanadium oxide, iron oxide, cobalt oxide Nickel oxide, niobium oxide, tin oxide, lithium silicon composite oxide, lithium titanium composite oxide (Lithium Titanium Composite Oxide: LTO, for example, Li ₄ Ti ₅ O ₁₂ , LiTi ₂ O ₄ , Li ₂ Ti ₃ O ₇ ), Metal oxide materials such as lithium vanadium composite oxide, lithium manganese composite oxide, lithium tin composite oxide, metal nitride materials such as lithium nitride, lithium cobalt composite nitride, lithium nickel composite nitride, tin, silicon, aluminum , Zinc, lithium and other metals or metal alloys mainly composed of these metal elements Or the like can be used Ranaru metallic material.

  As the binder, an appropriate material can be selected from the polymer materials exemplified as the binder for the positive electrode active material layer. Specifically, styrene butadiene rubber (SBR), polyvinylidene fluoride (PVdF), polytetrafluoroethylene (PTFE) and the like are exemplified. In addition, various additives such as a dispersant and a conductive material can be used as appropriate.

  The proportion of the negative electrode active material in the entire negative electrode active material layer is suitably 50% by mass or more, preferably 90% by mass or more and 99% by mass or less, more preferably 95% by mass or more and 99% by mass or less. . When using a binder, the ratio of the binder to the whole negative electrode active material layer can be, for example, 1% by mass or more and 10% by mass or less, and usually 1% by mass or more and 5% by mass or less is appropriate. is there.

The mass of the negative electrode active material layer provided per unit area of the negative electrode current collector is, for example, about 5 mg / cm ^{2 to} 20 mg / cm ² (preferably 5 mg / cm ^{2 to} 10 mg / cm ² ). It is. The density of the negative electrode active material layer can be set to, for example, about 0.5 g / cm ³ or more and 2 g / cm ³ or less (typically 1 g / cm ³ or more and 1.5 g / cm ³ or less). The thickness of is, for example, 40 μm or more (typically 50 μm or more), and can be 100 μm or less (typically 80 μm or less).

(Electrode plate inspection device 20)
As shown in FIG. 1, the electrode plate inspection apparatus 20 includes a probe 11 applied to a measurement point Tg of the electrode plate 100, a resistance component measurement unit 13 as a measurement unit that measures impedance and DC-IR of the measurement point Tg, The control unit 14 for controlling the measurement process and the mounting unit 12 for mounting the electrode plate 100 are provided.

(Probe 11)
The probe 11 includes a probe main body 112 and a measurement unit 118 connected to the cylindrical probe main body 112. The probe main body 112 is a cylindrical container, and has a predetermined electrolytic solution 116 and a counter electrode 114 provided in the electrolytic solution and provided with an electrode lead. The probe 11 is manufactured by injecting the electrolytic solution 116 after accommodating the counter electrode 114 in the probe main body 112 from the opening provided at the upper end of the probe main body 112. The probe main body 112 has a cylindrical shape with an open upper end, and has a measurement unit 118 that acts on a part of the inspection target (electrode active material layer 102) via the electrolytic solution 116 at the lower end. The measurement unit 118 has a measurement window that can change the opening area of the tip immersed in the electrolytic solution 116. The upper end (opening) of the probe main body 112 can be covered with a lid or the like. The probe 11 moves up and down in the vertical direction Z based on a signal from the control unit 14 and can be electrically connected to an inspection target (a part of the electrode active material layer 102) installed on the mounting unit 12. It is configured as follows. That is, the probe 11 is moved by a drive motor (not shown) that moves in the vertical direction Z.

  Examples of the material of the probe main body 112 and the lid include metal materials such as aluminum and steel, and resin materials such as polyethylene (PE), polypropylene (PP), polyphenylene sulfide, and polyimide. The shape of the probe main body 112 (outer shape of the container) can be, for example, a cylindrical shape, a rectangular parallelepiped shape, a cubic shape, and a shape obtained by processing and deforming them. For example, a needleless syringe made of polypropylene can be used.

(Counter electrode 114)
As the counter electrode 114, a carbon material, various metal materials, and the like can be used as long as they are stable in the electrolytic solution to be used in a voltage (or current) region that is input during impedance measurement. If the resistance to be inspected is relatively low, or if you want to separate and measure the reaction resistance more precisely, the counter electrode 114 has a low electrical resistivity (specific resistance) and a highly stable material in the measurement atmosphere (in the electrolyte) Is preferably used. For example, the above-described positive electrode or negative electrode active material layer forming material can be used as a counter electrode. The resistance derived from the counter electrode can be reduced by using the counter electrode 114 made of a positive electrode or a negative electrode. Therefore, the resistance of the electrode active material layer 102 to be inspected can be measured with higher accuracy. In addition, since the positive electrode and the negative electrode are stable in the electrolyte even when a relatively high voltage (for example, 100 mV to 1000 mV) is input, changes in the surface state, associated measurement errors, and variations in measurement values are unlikely to occur. .

  The area of the counter electrode 114 is preferably changed as appropriate according to the area of the measurement window 118 that is the horizontal sectional area of the measurement unit 118 (hereinafter simply referred to as the area of the measurement window). In general, since the magnitude of the resistance is inversely proportional to the measurement area, when it is desired to separate the resistance of only the inspection target (electrode active material layer 102), the area of the counter electrode 114 with respect to the working area of the measurement unit 118 (area of the measurement window) Needs to be secured more widely. In the present invention, the area of the counter electrode 114 is set to be 100 times or more (for example, 200 times or more, preferably 300 times or more, more preferably 500 times or more) wider than the working area of the measurement unit 118. As a result, the reaction resistance of the counter electrode 114 can be made negligibly small. For example, the resistance of the counter electrode 114 is set to 1/50 or less (preferably 1/100 or less) of the inspection target (measurement point Tg). Therefore, only the resistance (for example, film resistance, reaction resistance, or diffusion resistance) derived from the electrode active material layer 102 to be inspected can be accurately measured.

(Electrolytic solution 116)
As the electrolytic solution 116, a solution containing a supporting salt in a non-aqueous solvent (organic solvent) is typically used. As the non-aqueous solvent, for example, one or more organic solvents used in the electrolyte solution of the lithium ion secondary battery can be appropriately selected and used. Examples of preferable non-aqueous solvents include carbonates such as ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), vinylene carbonate (VC), and propylene carbonate (PC). . For example, a mixed solvent containing EC, DMC, and EMC at a volume ratio of 3: 4: 3 can be used.

As the supporting salt, for example, one or more lithium salts used as a supporting salt in a lithium ion secondary battery can be appropriately selected and used. Examples of the lithium salt include LiPF ₆ , LiBF ₄ , LiClO ₄ , LiEBF ₆ , Li (CF ₃ SO ₂ ) ₂ N, LiCF ₃ SO _{3 and the} like. A preferred example is LiPF ₆ . The concentration of the supporting salt in the nonaqueous electrolytic solution may be adjusted to be in the range of, for example, 0.7 mol / L or more and 1.3 mol / L or less (for example, 1.0 mol / L or more and 1.2 mol / L or less). preferable.

(Measurement unit 118)
The measurement unit 118 is connected to the probe main body 112 and electrically connects the counter electrode 114 in the probe and the measurement point Tg of the electrode active material layer 102 via the electrolytic solution 116. The smaller the working area (cross-sectional area) of the measurement unit 118 (measurement end portion that can be in contact with the measurement point Tg of the electrode active material layer 102), the more the influence of the resistance component derived from the counter electrode can be suppressed. On the other hand, if it is too small, the obtained result may vary depending on the state of the electrode active material layer 102 at the measurement point Tg. Thus, the active area of the measuring portion 118, for ^example, preferably be a 0.01cm ² ~0.1cm 2 (especially 0.02cm ² ~0.05cm ^2), where is about 0.03 cm ^2. Although the shape of the measurement part 118 is not specifically limited, A circular shape is preferable. In the case of a circular shape, the diameter of the measurement unit 118 (measurement end portion that can be in contact with the measurement point Tg of the electrode active material layer 102) is, for example, Φ1 mm to Φ10 mm (preferably Φ2 mm to Φ5 mm), and here is about Φ2 mm. . In the present embodiment, the measurement end that can be in contact with the measurement point Tg of the electrode active material layer 102 is the measurement window, and the action area (cross-sectional area) is the area of the measurement window.

(Placement part 12)
The mounting unit 12 includes a mounting table 108 as an electrode plate holding unit on which the electrode plate 100 to be inspected is mounted, and a jig (for example, a clamp) for fixing the electrode plate 100. And based on the signal from the control part 14, it is comprised so that it can move to a horizontal direction (the direction of the arrow of the direction X of FIG. 1, and the direction Y) by the drive motor which is not shown in figure. In the present embodiment, the moving unit includes a drive motor that moves the placement unit 12 in the direction X and the direction Y, and a drive motor that moves the probe 11 in the vertical direction Z.

  Moreover, the mounting part 12 is a container in which the mounting table 108 can hold the electrolytic solution 106, and the electrode plate 100 is placed in the electrolytic solution 106 to be held. In addition, the electrolyte solution 106 of the mounting part 12 is the same as the electrolyte solution 116 of the probe 11. Therefore, the measurement unit 118 is immersed in the electrolytic solution 106 of the mounting unit 12, whereby the electrolytic solution 106 of the mounting unit 12 and the electrolytic solution 116 of the probe 11 are connected, and the measurement point Tg of the electrode plate 100 is connected. The counter electrode 114 is electrically connected with the working area (measurement window area) defined by the measurement unit 118.

(Resistance component measuring unit 13)
The resistance component measurement unit 13 electrically connects the counter electrode 114 in the probe 11 and the measurement point Tg of the electrode active material layer 102. The resistance component measuring unit 13 can employ, for example, an analog method such as a Lissajous method or an AC bridge method, or a digital method such as a digital Fourier integration method or a fast Fourier transform method using noise application. For example, as the resistance component measuring unit 13, a potentio / galvanostat (PS / GS) capable of controlling current and voltage, and a frequency response analyzer (FRA) incorporating a sine wave oscillation circuit are provided. They can be used in combination. And based on the signal from the control part 14, an alternating current or alternating voltage is input between the probe 11 electrically connected, and the measurement point Tg, and an impedance is measured. The obtained impedance measurement result is sent to the control unit 14 as an output of the resistance component measurement unit 13.

Further, the resistance component measuring unit 13 measures an internal resistance value (DC-IR) with respect to a direct current. The temperature of the electrode plate 100 is constant at a predetermined temperature such as “25 ° C.”, for example.
As shown in FIG. 6, the resistance component measurement unit 13 discharges the measurement point Tg of the charged electrode plate 100 with a current of “10 A” for 5 seconds, and the same when 5 seconds have elapsed from the end of the discharge. The voltage at the measurement point Tg is measured. Next, after a 10-minute pause, the same measurement point Tg is charged with a current of “10 A” for 5 seconds, and the voltage at the same measurement point Tg when 5 seconds have elapsed from the end of this charging is measured. Based on each current value and each measured voltage value, a DC-IR value of the measurement point Tg of the electrode plate 100 of the lithium ion secondary battery is calculated.

  In the present embodiment, the voltage at the measurement point Tg of the electrode plate 100 at the start of discharge matches the voltage at the measurement point Tg of the electrode plate 100 after the end of charging. For example, the discharge electricity amount and the charge electricity amount with respect to the measurement point Tg are set to the same electricity amount. As a result, the state of charge at the measurement point Tg is made the same before and after the DC-IR measurement, and at the other adjacent measurement point Tg, the next measurement point is used for impedance measurement and DC-IR measurement. Charging / discharging by DC-IR measurement performed at Tg can be prevented from being affected. In addition, since the discharge electricity amount and the charge electricity amount need only be the same electricity amount, the discharge voltage, discharge current, and discharge time during discharge coincide with the charge voltage, charge current, and charge time during charge, respectively. It may be different or different. For example, when discharging, a discharge voltage, a discharge current and a discharge time suitable for DC-IR measurement are selected, and during charging, it is suitable to make the voltage at the measurement point Tg the same as before DC-IR measurement. The selected charging voltage, charging current and charging time are selected. Specifically, after the area of the measurement window of the measurement unit 118 of the probe 11 is specified, a discharge current and a discharge time until a predetermined amount of discharge electricity is measured when discharged at a selected discharge voltage are measured. Specifically, after specifying the area of the measurement window of the measurement unit 118 of the probe 11, when charging is performed at the selected charging voltage, the charging current and the charging time until a predetermined amount of charge is measured are measured. .

(Control unit 14)
The control unit 14 controls impedance measurement, probe 11 adjustment, and the like based on predetermined information. For example, adjustment of the position of the measurement point Tg to be inspected installed on the mounting unit 12, driving of the probe 11, control of impedance measurement, DC-IR measurement, etc., resistance calculation of the measurement point Tg based on the measured impedance, etc. Do. The configuration of the control unit 14 includes at least a ROM (Read Only Memory) that stores a program for performing such control, a CPU (Central Processing Unit) that can execute the program, and an input / output port. A signal (output) from the probe 11, the resistance component measurement unit 13, or the like is input to the control unit 14 via an input port. Further, the control unit 14 outputs a drive signal to the probe 11, the resistance component measurement unit 13, and the like via an output port.

  In the present embodiment, the electrode plate inspection apparatus 20 uses the impedance measured by the resistance component measuring unit 13 to determine the film resistance component and the reaction resistance component at each measurement point Tg of the electrode active material layer 102 as the characteristics of the electrode plate 100. A fitting unit 141 for fitting to the model is further provided. A measurement result of the measured impedance is sent to the fitting unit 141 via the control unit 14 (as a resistance value calculated by the control unit). The fitting unit 141 fits the characteristic model of the electrode plate 100 based on the sent resistance measurement result. For example, the characteristic model of the electrode plate 100 is determined as an equivalent circuit and stored in advance in a storage medium (for example, ROM, HDD, optical recording medium, magnetic recording medium, magneto-optical recording medium, flash memory, etc.). In addition, initial values of the parameters of the characteristic model of the electrode plate 100 are determined and stored in advance in a storage medium. Then, the initial value of each parameter of the characteristic model of the electrode plate 100 is fitted to the measured impedance. As a result, the film resistance component and the reaction resistance component at the measurement point Tg are represented by the characteristic model of the electrode plate 100. By being represented by the characteristic model of the electrode plate 100, it is possible to simulate the characteristic of the electrode plate at the measurement point Tg.

  An equivalent circuit as a characteristic model of the electrode plate 100 includes a resistance corresponding to circuit resistance and solution resistance, a parallel circuit of resistance and capacity corresponding to film resistance, and a parallel circuit of resistance and capacity corresponding to reaction resistance. , Are represented by a characteristic model composed of circuits connected in series.

  In the present embodiment, the characteristic model of the electrode plate 100 is fitted to the measured impedance for each measurement point Tg. At this time, if the initial value of each parameter of the characteristic model of the electrode plate 100 is fitted to the measured impedance, it is often necessary to perform many calculations each time. If the difference between the measured value and the initial value is large, the fitting may end abnormally, and the initial value may be changed and the fitting may have to be performed again. Therefore, for the fitting of the measurement point Tg adjacent to the already fitted measurement point Tg, the parameters of the characteristic model of the electrode plate specified for the fitted measurement point Tg are adopted and reset as initial values. Fitting from the reset initial value. The electrode active material layer 102 also has a high probability that each parameter of the characteristic model of the electrode plate 100 is approximated between the adjacent measurement points Tg. Therefore, by using the reset initial value, there is a high possibility that the calculation required for the fitting can be reduced compared to the fitting from the predetermined initial value, and between the initial value and the measured value. The divergence can be suppressed to a small level, and the possibility that the fitting may be malfunctioning can be reduced.

  In addition, the electrode plate inspection apparatus 20 calculates a DC resistance distribution calculation that calculates the distribution of the DC-IR in the electrode plate 100 at each measurement point Tg of the electrode active material layer 102 based on the resistance value measured by the resistance component measurement unit 13. A portion 142 is further provided. The DC resistance distribution calculation unit 142 calculates the DC-IR distribution at each measurement point for each area of the measurement window of the measurement unit 118 of the probe 11. Therefore, for one measurement point Tg, the DC-IR distribution is calculated for each area of the measurement window. In other words, the DC-IR distribution measured for each of the plurality of measurement points Tg is calculated for a specific area of the measurement window.

  Further, the electrode plate inspection apparatus 20 includes a pass / fail determination unit 143 that determines pass / fail of the electrical state of the electrode plate 100 based on the fitting result and the DC-IR distribution. The pass / fail determination unit 143 compares each parameter based on the fitting result with a threshold value indicating a normal range, and determines pass / fail of the electrical state of the electrode plate 100. Moreover, the quality determination part 143 compares the measurement result of DC-IR with the threshold value which shows a normal range, and determines the quality of the electrical state of the electrode plate 100. Moreover, the quality determination part 143 can determine the quality of an electrical state from the following viewpoints. For example, the distribution of DC-IR is calculated for each area of the measurement window, and the quality of the electrical state of the electrode plate 100 is determined for each area. Thereby, the quality of the electrode plate 100 can be determined for each depth of the electrode plate 100. Further, for example, the DC-IR for each area of the measurement window is compared with a specific measurement point Tg of the electrode plate 100, and the quality of the electrical state is determined based on whether this ratio is in the normal range. . As a result, the quality of the measurement point Tg of the electrode plate 100 can be determined based on not only the electrical characteristics of the surface but also the characteristics in the depth direction. Similarly, the pass / fail determination unit 143 can also determine pass / fail of the measurement point Tg of the electrode plate 100 by considering horizontal characteristics based on the DC-IR distribution for each area of the measurement window.

With reference to FIG. 3, the process procedure of the quality determination of the electrical characteristic of each measurement point Tg based on the measured value of each measurement point Tg by the electrode plate inspection apparatus 20 will be described.
The electrical property pass / fail determination process includes an initial value setting step (step S11 in FIG. 3), a moving step (step S12 in FIG. 3), an impedance measurement step (step S13 in FIG. 3), and a DC-IR measurement step. (Step S14 in FIG. 3) and determination of whether or not there is a next measurement point Tg (step S16 in FIG. 3). Further, the electrical characteristic pass / fail determination process includes a pass / fail determination process for the electrode plate 100 (step S17 in FIG. 3) and an electrode plate map creation process (step S18 in FIG. 3).

  In the initial value setting step (step S11 in FIG. 3), an equivalent circuit is selected as a characteristic model of the electrode plate 100 including the film resistance region c and the reaction resistance region d. Also, predetermined initial values are set for the parameters of the equivalent circuit. Further, the moving order (scanning order) of the first measurement point Tg and the measurement point Tg on the electrode plate 100 is determined. Moreover, the discharge voltage, discharge current, and discharge time at the time of discharge, and the charge voltage, charge current, and charge time at the time of charge are set so that the discharge electricity amount and the charge electricity amount for DC-IR measurement become the same electricity amount. Is determined.

  In the moving step (step S12 in FIG. 3), the probe 11 is sequentially moved from the first measurement point Tg as a starting point to the measurement points Tg on the electrode plate 100 in a predetermined movement order. At each measurement point Tg that is a movement destination, the measurement unit 118 of the probe 11 is allowed to act on a part of the electrode active material layer 102 facing the measurement point Tg, and the counter electrode 114 and the electrode active material layer 102 in the probe are measured via the electrolytic solution 116. The point Tg is electrically connected. Specifically, the probe 11 is moved in the vertical direction Z, and the mounting portion 12 is moved in the horizontal direction, so that the probe 11 is pressed against the measurement point Tg. As a result, the measurement point Tg of the electrode active material layer 102 is locally electrically connected to the counter electrode 114 in the probe via the electrolytes 116 and 106. In this embodiment, the measurement is performed in a state where the electrode plate 100 including the electrode active material layer 102 is placed in a container of a mounting table 108 filled with the same electrolyte solution 106 as the electrolyte solution 116 in the probe 11. In order to stably perform the measurement, it is preferable to proceed to the next step after holding the position of the probe 11 for several seconds to several minutes.

  In the impedance measurement step (step S13 in FIG. 3), the control unit 14 measures impedance by inputting an alternating current or alternating voltage between the electrically connected counter electrode 114 and the measurement point Tg.

Referring to FIG. 4, the impedance measurement process includes initial setting (step S21 in FIG. 4) and impedance measurement (step S22 in FIG. 4).
In the initial setting, a measurement frequency region, a frequency interval, a measurement time, an amplitude, and the like in impedance measurement for the measurement point Tg are set.

  As shown in FIG. 1, in impedance measurement, a current cable and a voltage cable are respectively connected to a lead of the counter electrode 114 and a portion where the current collector 104 of the electrode plate 100 is exposed, and an alternating current or an alternating voltage is input. The Then, impedance is measured based on the signal from the control unit 14.

  The frequency region to be measured in the impedance measurement may be a range in which a target resistance value (for example, a film resistance value and a reaction resistance value) can be calculated. For example, 100 kHz or less and 0.01 Hz or more (for example, 10 kHz or less 0 .1 Hz or higher, for example, 1 kHz or lower and 0.1 Hz or higher).

  An AC voltage of 100 mV to 1000 mV (for example, 200 mV to 1000 mV, or, for example, 300 mV to 1000 mV) is input between the electrically connected counter electrode 114 and the measurement point Tg. In general, in the impedance measurement of a non-aqueous electrolyte secondary battery, a voltage of about 5 mV to 10 mV is often input. However, in this embodiment, since the area of the measurement point Tg of the electrode active material layer 102 is very narrow, the influence of other resistance components (for example, solution resistance components) is large. Therefore, for example, in order to detect a response current related to a film resistance or a reaction resistance, it is preferable to input a voltage having a larger amplitude than in the past. By setting the input voltage within the above range, measurement noise can be suppressed, and highly accurate measurement can be performed. For the same reason, when measuring using an alternating current, an alternating current of, for example, 50 μA or more and 500 μA or less (for example, 100 μA or more and 500 μA or less) is input between the electrically connected counter electrode 114 and the measurement point Tg. It is preferable to measure the impedance.

  Further, the resistance value at the measurement point Tg of the electrode active material layer 102 is calculated based on the measurement result of the impedance. The film resistance and reaction resistance at the measurement point Tg can be read from the impedance curve L2 (see FIG. 2) of the Nyquist plot. The fitting unit 141 obtains each parameter value of the equivalent circuit by analyzing the shape of the Nyquist plot against the appropriately selected equivalent circuit (by curve fitting). The fitting unit 141 performs, for example, curve fitting by the least square method or the like.

  The impedance can be measured, for example, by measuring the impedance when the AC frequency is changed from 10 kHz to 0.1 Hz, but the necessary data is obtained from the obtained data. It can be extracted and analyzed.

  Referring to FIG. 3, the DC-IR measurement step (step S <b> 14 in FIG. 3) is a measurement point based on discharge or charge of a predetermined amount of electricity to measurement point Tg by resistance component measurement unit 13 in control unit 14. DC-IR of Tg is calculated.

  In the DC-IR measurement process of this embodiment, after discharging at the measurement point Tg, the discharged quantity of electricity is recharged. For example, after discharging, charging is performed with the amount of charge so that the voltage at the measurement point Tg becomes the voltage before the start of discharging. Further, in the DC-IR measurement step, for example, three areas of “large”, “medium”, and “small” are provided, and the DC-IR is measured for each of these three areas.

  Referring to FIG. 5, the DC-IR measurement process includes initial setting (step S31 in FIG. 5), change of measurement area (step S32 in FIG. 5), discharge (step S33 in FIG. 5), and charging (step in FIG. 5). S34), it is determined whether or not there is a next measurement area (step S35 in FIG. 5).

  In the initial setting (step S31 in FIG. 5), the amount of electricity, voltage, current, and time for discharging and charging are set for the measurement point Tg. The amount of electricity discharged and the amount of electricity charged are determined so that the voltage at the measurement point Tg becomes the same voltage before discharging and after charging.

In discharging (step S33 in FIG. 5), the measurement point Tg is discharged by the amount of electricity set at the set voltage, and the DC-IR at the time of discharge is measured.
In charging (step S34 in FIG. 5), the amount of electricity set by the voltage at which the measurement point Tg is set is charged, and the DC-IR at the time of charging is measured.

  As shown in the graph L5 of FIG. 6, discharging and charging discharge the measurement point Tg which is the probe voltage Vs before the start of discharging. When a predetermined amount of discharged electricity is discharged, discharging is stopped for a certain time. In addition, charging is started after a lapse of a certain time, and discharging is stopped when a predetermined amount of charge electricity is reached. Then, the measurement point Tg is set to the same voltage as the probe voltage Vs before the start of measurement after a predetermined time has elapsed. During discharge, the discharge voltage and discharge current are measured to calculate the DC-IR during discharge. Further, during charging, the charging voltage and charging current are measured to calculate DC-IR during charging. Note that DC-IR can be measured by selecting at least one of charging and discharging.

In this embodiment, the area of the measurement window is changed to “small”, “medium”, and “large”, and the DC-IR is measured for each measurement window size.
With reference to FIGS. 7 to 9, the measurement window area is changed to “small”, “medium”, and “large” and the DC-IR of the measurement point Tg is measured for each measurement window size. To do.

  As shown in FIG. 8, the measurement unit 118 has a measurement window having a diameter WD that is circular and variable in size. For example, the measurement unit 118 can change the area of the measurement window with a diaphragm mechanism (not shown).

  As shown in FIG. 9, the variable diameter WD is the diameter D1 when the area is “small”, the diameter D2 when the area is “medium”, and the diameter D3 when the area is “large”. That is, the relationship of diameter D1 <diameter D2 <diameter D3 is satisfied.

  As the area of the measurement window increases, the amount of charged ions related to the current contribution increases. That is, the range of influence that spreads substantially concentrically in the horizontal direction and in the depth direction from the position where the measurement unit 118 abuts expands according to the area of the measurement window.

  First, as shown in FIG. 8, with respect to the horizontal direction of the electrode plate 100, the influence range A1 when the area of the measurement window is “small”, the influence range A2 when the area is “medium”, and the area are The influence range A3 when “large” is set. That is, there is a relationship of influence range A1 <influence range A2 <influence range A3 with respect to the horizontal direction.

  Further, as shown in FIG. 7, with respect to the depth direction of the electrode plate 100, the influence range A1 when the area of the measurement window is “small”, the influence range A2 when the area is “medium”, and the area are The influence range A3 when “large” is set. That is, there is a relationship of influence range A1 <influence range A2 <influence range A3 with respect to the depth direction. Thus, as the area of the measurement window increases, the DC-IR measurement result includes information up to the depth of the electrode plate 100.

  As shown in FIG. 9, for example, the electrode plate 100 may have a defective portion with a high resistance due to contamination by foreign matters when the electrode plate is formed or insufficient filling of the electrode active material. Examples of such a defective portion include a defective portion BP1 generated on the outermost surface, a defective portion BP2 generated on the electrode plate, or a defective portion BP3 generated deep in the electrode plate. Usually, the defective portion BP1 generated on the outermost surface of the electrode plate 100 can be detected by visual observation or impedance measurement. On the other hand, the wrinkles of the electrode plate 100 and the defective portions BP2 and BP3 generated deeply cannot be detected visually or by impedance measurement. In this regard, in the DC-IR measurement, by increasing the area of the measurement window, the wrinkles of the electrode plate 100 and deep information can be acquired as the current magnitude. Therefore, it becomes possible to detect the defective portion BP2 and the defective portion BP3 that could not be detected conventionally. Further, since the defective part BP2 and the defective part BP3 are detected, the cause of the problem can be analyzed from the position and tendency of the problem.

  Note that as the area of the measurement window increases, the detection accuracy and the position specifying accuracy decrease. Therefore, at the measurement point Tg, DC-IR measurement results at different measurement window areas and DC-IR measurement results for each measurement window area at adjacent measurement points Tg are considered. As a result, the detection accuracy and position identification accuracy of the wrinkles of the electrode plate 100 and the defective portions BP2 and BP3 generated deeply are increased.

  Subsequently, as shown in FIG. 3, it is determined whether or not the electrode plate 100 has the next measurement point Tg (step S16 in FIG. 3). If it is determined that there is the next measurement point Tg (YES in step S16 in FIG. 3), the process returns to step S12, the probe 11 is moved to the next measurement point Tg in step S12, and then step S13 and The process of step S14 is executed.

  That is, the probe 11 is continuously scanned in a predetermined pattern on the electrode active material layer 102 while maintaining the electrical connection between the measurement unit 118 of the probe 11 and the measurement point Tg of the electrode active material layer 102. Thus, the resistance distribution in the plane and inside of the electrode active material layer 102 is measured. Alternatively, the measurement unit 118 of the probe 11 and the measurement point Tg of the electrode active material layer 102 are intermittently electrically connected, and the probe 11 is scanned in a predetermined pattern on the electrode active material layer 102, whereby the electrode active material The resistance distribution in the plane and in the layer 102 is measured.

  When it is determined that there is no next measurement point Tg (NO in step S16 in FIG. 3), the control unit 14 performs a pass / fail determination step in which the pass / fail determination unit 143 determines pass / fail of the electrode plate 100 (step in FIG. 3). S17).

  Referring to FIG. 10, the pass / fail determination step (step S <b> 17 in FIG. 3) includes acquisition of a measurement value for each measurement point (step S <b> 41 in FIG. 10), pass / fail determination based on impedance (step S <b> 42 in FIG. 10), It has pass / fail judgment based on DC-IR (step S43 in FIG. 10) and pass / fail judgment of the electrode plate (step S44 in FIG. 10).

  In acquisition of measurement values for each measurement point (step S41 in FIG. 10), the pass / fail judgment unit 143 obtains measurement values in a range necessary for pass / fail judgment from the storage medium. Since the impedance measurement data has a large amount of data, the necessary data may be acquired when necessary for the determination process. Since the measurement data of DC-IR is the total number of measurement points Tg × the number of measurement window areas, all data may be acquired first, or necessary data is acquired when necessary for determination processing. You may do it.

  In the pass / fail determination based on impedance (step S42 in FIG. 10) and the pass / fail determination based on DC-IR (step S43 in FIG. 10), a determination method required at that time can be selected from various determination methods. it can. Since the value of DC-IR corresponds to the value of direct current with respect to a predetermined direct current voltage, determination based on DC-IR is one aspect of determination based on direct current.

  As an example of the determination method, the pass / fail determination unit 143 is determined to be non-defective depending on whether or not the DC-IR values acquired for a plurality of measurement points Tg are within the non-defective range for DC-IR determination. It can be determined whether or not. At this time, it can be determined whether or not it is a non-defective product depending on whether or not the DC-IR value is within the non-defective range for each area of the measurement window. If the area of the measurement window is “medium” or “large”, the quality of the electrode plate 100 can be determined according to the state of the wrinkles of the electrode plate 100. In addition, regarding the DC-IR values in and within the electrode active material layer 102, the electrode plate 100 can also be determined as a non-defective product on condition that the maximum value and the minimum value are within the non-defective range.

  Moreover, the pass / fail judgment unit 143 can also identify a defective part. Specifically, the position of the defective portion can be specified based on comparison of measurement results at different measurement window areas at the same measurement point Tg or comparison of measurement results at different measurement points Tg. . For example, it is assumed that a defective portion is found when the area of the measurement window is “large” at the same measurement point even though the defective portion cannot be found when the area of the measurement window is “small”. At this time, the defective part can specify that the area of the measurement window is within the influence range of “large” and the area of the measurement window is outside the influence range of “small”. By integrating the measurement results for each area of the measurement window, the position of the defective part can be specified.

  Similarly, with respect to the determination of the impedance, it is possible to determine whether or not the impedance value obtained for the plurality of measurement points Tg is a non-defective product depending on whether or not the value is within the non-defective range.

  As another example of the determination method, the pass / fail determination unit 143 calculates variations in the values of a plurality of DC-IR acquired for a plurality of measurement points Tg, and determines whether or not the calculated variations are within the non-defective product range. It is possible to determine whether or not the product is non-defective. Also at this time, if the area of the measurement window is “medium” or “large”, it is possible to determine whether the electrode plate 100 is good or bad according to the state of the electrode plate 100 generated in the wrinkles or deeply.

  Similarly, it is also possible to calculate a plurality of impedance values obtained for a plurality of measurement points Tg and determine whether the calculated variation is a non-defective product according to whether the calculated variation is within a non-defective product range. it can. At this time, the magnitude of impedance, the value of the real axis value, or the value of the imaginary axis value may be compared with each other.

Such a determination result can be used for, for example, grasping the formation state of the oxide film on the electrode after the aging treatment, or analyzing the change (degradation) of the resistance in the electrode after the durability test.
In addition, information that can be acquired by DC-IR measurement includes information on the electrode plate 100 in the horizontal direction.

  Referring to FIG. 8, for example, the charged ions wrap around the measurement window of measurement unit 118 even from the outside of the measurement window area in the horizontal direction, so that electrode plate 100 does not face the measurement window of measurement unit 118. It becomes possible to acquire information about the wraparound of charged ions in the surrounding portion to the measurement window. In general, if the positive electrode plate and the negative electrode plate are opposed to each other, the charge ions are exchanged in the depth direction. However, at positions where the positive electrode plate and the negative electrode plate are not opposed to each other, the charge ions are also attracted from the horizontal direction. It becomes like this. In general, in a lithium ion battery, since the negative electrode plate is larger than the positive electrode plate, the charge ions on the negative electrode plate not facing the positive electrode plate move in the horizontal direction. In other words, it is preferable that the characteristics relating to the horizontal movement of the charged ions in the negative electrode plate not facing the positive electrode plate are also grasped and the negative electrode plate or the like is designed in consideration of this characteristic. However, it is known that the movement characteristics of charged ions in the horizontal direction have a singular difference depending on the position of the electrode plate 100, and it is more preferable when the singular difference is taken into consideration. In this regard, the probe 11 of the present embodiment can acquire the characteristics of the charged ions in the horizontal direction with respect to portions other than the opposing portions of the measurement window area. Accordingly, it is possible to confirm the uniformity of the electrode active material layer 102 and to acquire the movement characteristics of the charged ions in the horizontal direction in the portion of the negative electrode plate not facing the positive electrode plate. Further, by changing the size of the area of the measurement window, it is possible to confirm the uniformity of the electrode active material layer 102 and to acquire the movement characteristics of the charged ions in the non-opposing portion in the horizontal direction in more detail. .

  That is, by the DC-IR measurement, not only the depth characteristics of the electrode plate 100 can be obtained but also the horizontal characteristics of the electrode plate 100 can be obtained with respect to the specific movement of the charged ions of the electrode plate 100. Furthermore, the characteristics in the depth direction and the horizontal direction can be obtained in more detail by DC-IR measurement in which the sizes of the areas of the measurement windows are different.

  Subsequently, as shown in FIG. 3, an electrode map creating step for creating an electrode plate map is performed (step S18 in FIG. 3). In the electrode plate map creation step, the control unit 14 creates a DC-IR distribution map on the electrode plate 100 by associating the DC-IR value with the measurement point Tg of the electrode plate 100 for each area of the measurement window. . Since the distribution map can be used to find the above-described defect portion, it is possible to analyze the cause of the defect from the position and tendency of the defect.

When the electrode map creation step (step S18 in FIG. 3) is completed, the electrical characteristic pass / fail determination process is ended.
As described above, according to the present embodiment, the following effects can be obtained.

  (1-1) The DC-IR of the measurement point Tg of the electrode plate 100 can be measured, and the measurement point Tg after the measurement can be returned to the charged state before the measurement. By returning to the original state, DC-IR at other measurement points Tg can also be appropriately measured, and a DC-IR distribution can be obtained for the entire electrode plate 100. Therefore, the detailed state of the electrode plate 100 of the secondary battery can be inspected more accurately. Note that the DC-IR measurement may be performed during charging or during discharging.

(1-2) The charging voltage or discharging voltage can be set to a voltage suitable for DC-IR measurement, or can be set to a voltage suitable for returning the amount of electricity.
(1-3) The state relating to the current at each measurement point Tg of the electrode plate 100 can be determined by comparing the direct current (DC-IR) at different measurement points Tg. That is, it is possible to determine the quality distribution of the current with respect to the electrode plate 100.

  (1-4) By adjusting the charging voltage and discharging voltage for the measurement point Tg, the amount of electricity is returned by discharging after charging, or the amount of electricity is returned by charging after discharging. .

  (1-5) The influence of the area of the measurement window is reflected, and the DC-IR for the measurement point Tg can be measured. As the area of the measurement window increases, the effect of deep depth is included. Therefore, if the area of the measurement window is large, a depth characteristic that cannot be obtained by impedance measurement that measures a state in a range close to the surface can be obtained. Moreover, the depth in which a malfunctioning part exists can also be acquired by measuring in several areas.

(1-6) The opening area of the measurement window can be easily changed by a diaphragm mechanism or the like. Measurement becomes easy.
(1-7) Since the fitting is performed on the characteristic model of the secondary battery, the battery model based on the impedance distribution acquired with respect to the electrode plate 100 can be compared with the measurement result. Moreover, the deterioration state of the electrode plate 100 can be determined based on such a comparison result.

(Second Embodiment)
A second embodiment of the electrode plate inspection apparatus and the electrode plate inspection method will be described with reference to FIGS.

  This embodiment is different from the first embodiment in that the impedance in the transient state of the electrode plate is measured. In addition, about the structure similar to 1st Embodiment, the same code | symbol is attached | subjected and detailed description is omitted. For example, the electrode plate 100, the probe 11, the placement unit 12, and the resistance component measurement unit 13 that are the positive electrodes of the secondary battery have the same configuration as in the first embodiment. The resistance component measuring unit 13 sets the predetermined current amount for charging / discharging the measurement point Tg of the electrode plate 100 to a current amount smaller than the rated current amount (1C) of the measurement point Tg of the electrode plate 100 (for example, 0 .1C) to a current amount greater than 1C (eg, 10C or 20C).

  As shown in FIG. 11, the electrode plate inspection apparatus 120 measures the equilibrium state impedance and the transient state impedance of the electrode plate 100 of a secondary battery having a nonaqueous electrolyte such as a lithium ion secondary battery, and The transient characteristic component obtained from the resistance component is measured.

  In this embodiment, the probe 11 has a measurement window size (diameter WD (see FIG. 8)) of about 5 μm corresponding to the particle size of the active material particles. The particle size is set to be twice or less. Thereby, the behavior of the active material particles in one particle, that is, the electrochemical phenomenon due to the transient characteristics in the active material itself can be measured.

(Control unit 30)
The control part 30 which comprises an electrode plate inspection apparatus is demonstrated. The control unit 30 has the function of the control unit 14 described in the first embodiment. That is, the probe 11 moves up and down in the vertical direction Z based on a signal from the control unit 30, and can be electrically connected to an inspection target (a part of the electrode active material layer 102) installed on the mounting unit 12. It is configured. Further, the placement unit 12 is configured to be movable in a horizontal direction (directions of arrows X and Y in FIG. 1) by a drive motor (not shown) based on a signal from the control unit 30.

  The controller 30 measures the impedance of the electrode plate 100 in the equilibrium state, the impedance in the transient state, and the transient state-specific component. Here, the transient state-specific component is a component obtained based on impedance measurement when the electrode plate 100 is in a transient state where the electrode plate 100 is charged and discharged. When the electrode plate 100 is in an equilibrium state where it is maintained at a constant voltage, the active material of the electrode plate 100 is in an electrically uniform state. On the other hand, when the electrode plate 100 is in a transient state, the active material of the electrode plate 100 is temporarily in an electrically non-uniform state. That is, the individual active materials constituting the electrode plate 100 have uneven potentials or the like between the surface and the inside of the active material. In general, when such unevenness of the potential in the active material is quickly resolved, the electrode plate performance is good, while when it takes time to resolve the unevenness of the potential, etc., it is determined that the electrode plate performance is poor. Can do. Therefore, in this embodiment, the quality of the electrode plate state is determined based on the transient state-specific component obtained based on the impedance measured when the electrode plate 100 is in the transient state.

The control unit 30 is connected to a resistance component measurement unit 13 that supplies a direct current and an alternating current to the electrode plate 100.
(Resistance component measuring unit 13)
The resistance component measuring unit 13 adjusts the entire state of the electrode plate 100 or a part of the charged state (SOC: State of Charge) such as the measurement point Tg by charging or discharging. Since the SOC is the ratio [%] of the amount of charged electricity to the total capacity of the electrode plate 100, the relationship of “charged electricity amount = total capacity of the electrode plate × SOC” is established. Below, for convenience of explanation, it explains using both charge amount of electricity and SOC.

  The resistance component measuring unit 13 can superimpose the alternating current of the frequency response analyzer on the charge / discharge current of the potentio / galvanostat. Therefore, the resistance component measurement unit 13 can cause the control unit 30 to measure a transient state impedance that is a transient impedance of the transient state electrode plate 100 in which charging or discharging is continued.

  When the impedance measurement unit 13 measures the impedance in the equilibrium state, the resistance component measurement unit 13 continuously flows the AC wave shown in the graph L11 in FIG. Further, when measuring the impedance in the transient state, the resistance component measuring unit 13 continues the charging and discharging from the start to the end with the selected predetermined amount of current as a rectangular wave shown in the graph L31 of FIG. Can be shed. The resistance component measurement unit 13 can measure the impedance in the transient state with a large difference from the impedance in the equilibrium state by flowing a direct current larger than 1C through the electrode plate 100. In addition, the resistance component measurement unit 13 can maintain a long period in which the electrode plate 100 is in a transient state by flowing a direct current larger than 1C through the electrode plate 100. In order to increase the difference between the impedance in the equilibrium state and the impedance in the transient state, the electrode plate 100 may be charged at 10C or more, preferably 20C or more.

  The resistance component measuring unit 13 has a function of supplying an alternating current for measuring complex impedance to the electrode plate 100. The resistance component measuring unit 13 can generate an alternating current corresponding to the set amplitude and the set frequency, and can apply the generated alternating current to the electrode plate 100. Further, the resistance component measuring unit 13 can sweep the frequency of the alternating current, and the unidirectional until the measurement frequency reaches the upper limit value or the lower limit value within a predetermined frequency range defined by the upper limit value and the lower limit value. To change. The upper limit value and the lower limit value are different values, and a high frequency relative to the upper limit value and a low frequency relative to the lower limit value are set. For example, the resistance component measurement unit 13 outputs an alternating current having an amplitude of a predetermined magnitude as an alternating current that changes in 10 seconds from an upper limit value of 10 kHz to a lower limit value of 1 Hz.

  Note that it is preferable that the frequency of the alternating current does not change during one cycle. In the predetermined frequency range, the upper limit value may be higher than 10 kHz and the lower limit value may be lower than 1 Hz as long as the impedance in the transient state can be measured. However, the lower limit value is preferably equal to or higher than a frequency that does not change the degree of a transient state due to a direct current during one cycle. Further, if the lower limit value is lowered, the increase in time required for measurement becomes large. Therefore, although it depends on the period during which the electrode plate 100 can be maintained in a transient state, it is preferably 1 Hz or more, for example.

  The resistance component measuring unit 13 determines the amount of direct current and the amplitude of the alternating current so that the transient impedance can be measured. Although the length of time during which charging / discharging is in a transient state varies depending on the type and characteristics of the electrode plate 100, for example, in the resistance component measurement unit 13, the amount of direct current is 2 which is the magnitude of the amplitude of the alternating current. It is preferable that it is twice or more, preferably 10 times or more, and more preferably 25 times or more.

  In the resistance component measuring unit 13, the control unit 30 sets the amount and voltage of the direct current, the amplitude, the voltage, the upper limit and lower limit of the frequency, the sweep period, and the like. In addition, the resistance component measuring unit 13 outputs or stops the direct current or the alternating current according to the direct current output start signal and the output stop signal, the alternating current output start signal and the output stop signal input from the control unit 30. Do.

  Conversely, the resistance component measuring unit 13 outputs the set value and current value of the output DC current and the set value and current value of the output AC current to the control unit 30. Further, the resistance component measuring unit 13 outputs signals corresponding to the AC voltage, DC voltage, and impedance measured with respect to the electrode plate 100 to the control unit 30.

The control unit 30 acquires DC current, AC current setting information, and the like from the signal input from the resistance component measurement unit 13.
The control unit 30 includes a processing unit 40 that performs a calculation process for measuring a transient state-specific component of the electrode plate 100 and a storage unit 50 that holds data used for measurement of the transient state-specific component of the electrode plate 100. .

(Storage unit 50)
The storage unit 50 is a non-volatile storage device such as a hard disk or a flash memory, and holds various data. In the present embodiment, the storage unit 50 holds a parameter 51 required for measuring the transient state specific component and determination data 52 for determining the electrode plate state. As the determination data 52, a determination threshold value (for example, see FIG. 24) for determining the quality of the electrode plate 100 determined in advance based on experiments, experience, and theory based on the transient state-specific component is set.

(Processing unit 40)
The processing unit 40 is the same as the control unit 14 of the first embodiment, and includes a microcomputer configured with a CPU, a ROM, a RAM, and the like. The processing unit 40 can use information such as voltage, current, measurement frequency, impedance, and the like acquired by the control unit 30. The processing unit 40 is connected to the storage unit 50, and can exchange data with the storage unit 50. The processing unit 40 executes various processes in the processing unit 40 by, for example, executing various programs held in the ROM or RAM by the CPU.

  The processing unit 40 includes an SOC adjustment unit 41 as a first adjustment unit that adjusts the SOC of the electrode plate 100. In addition, the processing unit 40 includes an equilibrium state impedance measurement unit 42 that measures the impedance of the electrode plate 100 in an equilibrium state as an equilibrium state impedance, and a transient state impedance that measures the impedance of the electrode plate 100 in a transient state as a transient state impedance. A measurement unit 43. The equilibrium state impedance measurement unit 42 constitutes an equilibrium state impedance acquisition unit, and the transient state impedance measurement unit 43 constitutes a transient state impedance acquisition unit and a second adjustment unit. The processing unit 40 also includes a Nyquist diagram creation unit 44 for creating a Nyquist diagram, and a parameter calculation unit 45 as a specific component calculation unit for fitting the impedance measurement result to the equivalent circuit to calculate the resistance component of the equivalent circuit. And a determination unit 48 for determining the electrode plate state.

  The SOC adjustment unit 41 adjusts the entire SOC of the electrode plate 100 to an appropriate SOC or the like for measurement of equilibrium state impedance, measurement of impedance in a transient state, or the like. The SOC adjusting unit 41 adjusts the electrode plate 100 to a predetermined SOC by instructing the resistance component measuring unit 13 to charge and discharge current. The SOC adjustment unit 41 calculates the SOC by measuring the electrode plate 100 by a well-known method, or calculates the SOC based on the integration of the charged and discharged electric quantity.

  The equilibrium state impedance measurement unit 42 performs a process (equilibrium state impedance measurement step) of measuring an equilibrium state impedance that is an impedance measured at a measurement frequency while the electrode plate 100 is in an equilibrium state. The equilibrium state impedance measurement unit 42 instructs the resistance component measurement unit 13 to charge / discharge the direct current so that the electrode plate 100 is in an equilibrium state, and also instructs the supply and stop of the alternating current for measurement. The equilibrium state impedance measurement unit 42 acquires the impedance Z measured from the start to the end of the measurement from the resistance component measurement unit 13. The unit of impedance Z is [Ω] (ohms). Impedance Z is expressed as in equation (1) by the real component Zr [Ω] and the imaginary component Zi [Ω] which are vector components. “J” is an imaginary unit. Hereinafter, the unit [Ω] is omitted.

Z = Zr−jZi (1)
The transient state impedance measurement unit 43 performs a process (transient state impedance measurement process) of measuring a transient state impedance that is an impedance repeatedly measured at a measurement frequency while the electrode plate 100 is in a transient state. The transient state impedance measuring unit 43 instructs the resistance component measuring unit 13 to charge and discharge a direct current so that the electrode plate 100 enters a transient state, and also instructs the supply and stop of the alternating current for measurement. The transient impedance measurement unit 43 acquires the impedance Z measured from the start to the end of the measurement from the resistance component measurement unit 13.

  The Nyquist diagram creation unit 44 creates a Nyquist diagram from the real component Zr and the imaginary component Zi, which are vector components, based on the impedances Z of the plurality of frequencies included in the measurement frequency.

  The Nyquist diagram creation unit 44 creates an impedance curve L2 (see FIG. 2) on a complex plane whose horizontal axis is a real axis and whose vertical axis is an imaginary axis. The impedance curve L2 is an example of a Nyquist diagram corresponding to the electrode plate 100 in an equilibrium state maintained at a predetermined SOC. The impedance curve L2 is obtained by plotting the real component Zr and the imaginary component Zi of the impedance Z on a complex plane. The impedance curve L2 is based on the impedance Z measured for each frequency by changing the measurement frequency of the alternating current supplied from the resistance component measurement unit 13 to the electrode plate 100.

  For example, according to the impedance curve L2 shown in FIG. 2, the frequency range corresponding to the “diffusion region d” is “0.1 Hz” or less, and the frequency range corresponding to the “reaction resistance region c” is “0.1 Hz”. It is larger than “100 Hz”. The frequency range corresponding to the “solution resistance region b” is “100 Hz” and its vicinity, and the frequency range corresponding to the “circuit resistance region a” is higher than “100 Hz”.

  Referring to FIG. 11, the Nyquist diagram creation unit 44 performs a process of representing the impedance curves L41, L42 and the like (see FIG. 18) of the transient response impedance created on the complex plane in three dimensions. The Nyquist diagram generator 44 adds a time axis to the complex plane (see FIG. 19), an axis conversion process (see FIG. 20) for converting the added time axis into the SOC, and a specific SOC ( An estimation process (see FIG. 21) for estimating a Nyquist diagram for (charged electricity amount) is performed.

  As illustrated in FIG. 19, in the time axis addition process, the Nyquist diagram creation unit 44 adds a time axis indicating the measurement time to three-dimensionalize the complex plane. The measurement points constituting the two-dimensional impedance curves L41 and L42 (see FIG. 18) are acquired together when the measurement time measures the transient response impedance. For example, when the transient response impedance is measured nine times at the measurement frequency, the graph shows Nyquist diagrams L51 to L59 where the measurement is started from time t0 to t8. Note that the Nyquist diagram L50 shows an example of an impedance curve when the measurement timing does not affect the measurement result and it is sufficient to represent it in two dimensions on the complex plane.

  As illustrated in FIG. 20, the Nyquist diagram creation unit 44 associates the SOC values c0 to c8 of the electrode plate 100 with the times t0 to t8 on the time axis in the axis conversion process. In the impedance measurement in the transient state, since the amount of current to be charged / discharged is determined, the SOC of the electrode plate 100 corresponding to the elapsed time from the start of charging / discharging can be calculated.

  As shown in FIGS. 20 and 21, the Nyquist diagram creation unit 44 calculates the transient response impedance measured at the measurement frequency (range from the upper limit value to the lower limit value) in the estimation process when the SOC is a specific SOC. presume. For example, in FIG. 20, the Nyquist diagrams L51 to L59 allow the impedance to the SOC between the two measurement points to be estimated on the line LC by connecting the measurement points having the same frequency to each other by the line LC. it can. For example, the intersection of the line LC connecting the measurement points and the plane parallel to the complex plane corresponding to each SOC is estimated as the impedance curve L6 of the transient response estimated for each SOC. In this way, an impedance curve L71 (see FIG. 21) of the transient response estimated corresponding to the specific SOC value cx is obtained. That is, the impedance curve L71 (Nyquist diagram) in a specific SOC is acquired from the transient impedance measured by repeating the measurement frequency for the electrode plate 100 in the transient state.

  The parameter calculation unit 45 sets the equivalent circuit GC (see FIG. 15) as an equivalent circuit corresponding to the electrode plate 100. Similar to the fitting unit 141 of the first embodiment, the parameter calculation unit 45 causes the equivalent circuit GC to fit the impedance measurement result to calculate various parameters set in the equivalent circuit. The parameter calculation unit 45 acquires a transient state specific component based on the equivalent circuit parameter fitted to the equilibrium impedance and the equivalent circuit parameter fitted to the transient impedance (a specific component calculation step). The parameter of the equivalent circuit is one mode indicating the electrode plate state.

  As shown in FIG. 15, an example of an equivalent circuit GC indicating the characteristics of the electrode plate 100 includes an inductance L1, a resistor R1, a parallel circuit of a resistor R2 and a capacitor C2, a resistor R3 and a diffusion resistor Wo1 connected in series. A parallel circuit composed of capacitors C1 connected in parallel is constituted by a series circuit connected in series. The value of each passive element of the equivalent circuit GC constitutes the parameter of the equivalent circuit GC.

  In the fitting analysis, the set equivalent circuit GC is fitted to an impedance curve (for example, the impedance curve L2 in FIG. 2). By this fitting analysis, parameters that make the frequency response of the equivalent circuit GC equivalent to the impedance curve are set in each passive element of the equivalent circuit GC.

  As shown in FIG. 23, the parameter calculation unit 45 acquires a transient state-specific component. The parameter calculation unit 45 determines a specific SOC, and calculates a parameter of the equivalent circuit GC fitted to the equilibrium state impedance in the determined specific SOC. Further, the parameter calculation unit 45 calculates a parameter of the equivalent circuit GC fitted to the transient impedance estimated for the specific SOC. Then, the parameter calculation unit 45 acquires the transient state specific component based on the difference between the parameter of the equivalent circuit GC corresponding to the equilibrium state impedance and the parameter of the equivalent circuit GC corresponding to the transient state impedance.

  For example, as shown in a graph L83 in FIG. 23, the parameter calculation unit 45 calculates the value of the resistance R3 of the equivalent circuit GC corresponding to the equilibrium state impedance and the value of the resistance R3 of the equivalent circuit GC corresponding to the transient state impedance. The difference is calculated as a transient state-specific component ΔR3. Similarly, as shown in a graph L81 in FIG. 23, the parameter calculation unit 45 sets the value of the resistance R1 of the equivalent circuit GC corresponding to the equilibrium impedance and the resistance R1 of the equivalent circuit GC corresponding to the transient impedance. The difference from the value may be calculated as the transient state specific component ΔR1. Further, as shown in a graph L82 in FIG. 23, the parameter calculation unit 45 calculates the value of the resistance R2 of the equivalent circuit GC corresponding to the equilibrium state impedance and the value of the resistance R2 of the equivalent circuit GC corresponding to the transient state impedance. The difference may be calculated as a transient state-specific component ΔR2.

  As shown in FIG. 11, the determination unit 48 compares the transient state-specific component ΔR3 with a determination threshold value for determining the deterioration state of the electrode plate 100. If the transient state-specific component ΔR3 is equal to or greater than the determination threshold value, the electrode plate 100 is used. If the transient state-specific component ΔR3 is less than the determination threshold, it is determined that the electrode plate 100 is not deteriorated. As shown in the graph L91 in FIG. 24, the electrode plate 100 tends to have a transient state-specific component ΔR3 (resistance value) that increases as the period of use increases or the number of uses increases. . That is, if the magnitude of the transient state specific component ΔR3 is less than the determination threshold, the electrode plate 100 is in the use OK range that is appropriate for use, and conversely, the magnitude of the transient state specific component ΔR3 is greater than or equal to the determination threshold. If it exists, it will be in the use NG range where use is inappropriate. Such a determination threshold is determined from experience and experiments.

  The determination unit 48 may determine the deterioration of the electrode plate 100 by comparing the transient state specific component ΔR2 or the transient state specific component ΔR1 with a determination threshold value for determining the deterioration state of the electrode plate 100. . At this time, as shown in FIG. 23, the transient state specific components ΔR3, ΔR2, and ΔR1 corresponding to the resistors R3, R2, and R1 of the equivalent circuit GC have a relationship of “ΔR3> ΔR2> ΔR1”. Therefore, the determination threshold value for determining the deterioration state of the electrode plate 100 to be compared with these transient state-specific components ΔR3, ΔR2, and ΔR1 is also set as a different value corresponding to each of the resistors R3, R2, and R1. .

In addition, the control unit 30 can output the determination result of the electrode plate state to the outside as a measurement result regarding the deterioration of the electrode plate 100.
(Electrode plate state judgment processing)
Next, the procedure of the electrode plate state determination process performed based on the measurement of the transient state specific component in the control unit 30 will be described.

  The electrode plate state determination process is started automatically or in response to an instruction from the outside in response to the necessity of determining the electrode plate state. The electrode plate state can be measured in the same manner whether the electrode plate 100 is charged or discharged. Below, the case where an electrode plate state is determined when the electrode plate 100 is discharged is demonstrated, and the description about the case where an electrode plate state is determined when the electrode plate 100 is charged is omitted for convenience of explanation.

With reference to FIG. 12, a processing procedure for determining whether or not the electrical characteristics are good as an example of the state of each measurement point Tg based on the measurement value of each measurement point Tg by the electrode plate inspection apparatus 120 will be described.
The electrical property pass / fail determination process includes an initial value setting step (step S11 in FIG. 12) and a moving step (step S12 in FIG. 12). In addition, the electrical characteristic pass / fail determination process includes an equilibrium state impedance acquisition step (step S13A in FIG. 12), a transient state impedance acquisition step (step S13B in FIG. 12), and whether there is a next measurement point Tg. Determination (step S16 in FIG. 12). The electrical property pass / fail determination processing includes a state determination step (step S171 in FIG. 12) for determining pass / fail of the electrical properties of the electrode plate 100 and an electrode plate map creation step (step S18 in FIG. 12). ing.

  The initial value setting step (step S11 in FIG. 12) includes the same configuration as that of the first embodiment, and the equivalent circuit GC is selected as the characteristic model of the electrode plate 100. Also, predetermined initial values are set for the parameters of the equivalent circuit GC. Further, the moving order (scanning order) of the first measurement point Tg and the measurement point Tg on the electrode plate 100 is determined. Further, during the transient state impedance measurement, the discharge current and the discharge time and the charge current and the charge time are determined so that the discharge electricity amount and the charge electricity amount are the same.

The moving process (step S12 in FIG. 12) is the same as in the first embodiment.
(Equilibrium impedance acquisition process)
As shown in FIG. 13, when the equilibrium state impedance acquisition step (step S <b> 13 </ b> A in FIG. 12) is started, the control unit 30 acquires the SOC of the electrode plate 100 with the SOC adjustment unit 41 and the entire electrode plate 100. The SOC adjustment step (step S120 in FIG. 13) is performed to adjust the SOC to the measurement SOC. When the entire SOC of the electrode plate 100 is adjusted to the measurement SOC, the control unit 30 measures the equilibrium impedance in an equilibrium impedance measurement step (step S121 in FIG. 13). In the measurement of the equilibrium state impedance, the control unit 30 obtains a response voltage by applying an AC current for measuring the equilibrium state impedance to the electrode plate 100 adjusted to a specific SOC. The alternating current applied at this time is the alternating current shown in the graph L11 in FIG. 14A, and the response voltage is obtained as the voltage shown in the graph L12 in FIG. 14B. In addition, when applying an alternating current, the direct current for charging / discharging is not applied.

  As illustrated in FIG. 13, when the response voltage is acquired, the control unit 30 determines whether to readjust the SOC of the electrode plate 100 (step S122 in FIG. 13). The measurement SOC is set, for example, every 5% from 40% to 60%, and the SOC of the entire electrode plate 100 needs to be readjusted until the SOC is measured for all the measurement SOCs. If the equilibrium impedance is measured for the measuring SOC, the SOC readjustment is unnecessary.

  If control unit 30 determines that SOC readjustment is necessary (YES in step S122 of FIG. 13), the process returns to the SOC adjustment step, and the equilibrium impedance of electrode plate 100 adjusted to the next measurement SOC is obtained. Measure.

  When determining that the SOC readjustment is unnecessary (NO in step S122 in FIG. 13), the controller 30 creates a Nyquist diagram for each measurement SOC in the Nyquist diagram creation step (step S123 in FIG. 13). . A Nyquist diagram as shown in the impedance curve L2 (see FIG. 2) is created from the equilibrium impedance. Further, the control unit 30 analyzes the generated Nyquist diagram and performs a parameter calculation step (fitting) for calculating the parameters of the equivalent circuit GC by fitting the equivalent circuit GC shown in FIG. 15 (FIG. 13). Step S124). And the control part 30 will complete | finish an equilibrium state impedance acquisition process, if a parameter calculation process is complete | finished.

(Transient state impedance acquisition process)
Next, the control unit 30 starts a transient state impedance acquisition step (step S13B in FIG. 12).

  First, as shown in FIG. 16, the control unit 30 obtains the SOC of the electrode plate 100 by the SOC adjusting unit 41 and adjusts the SOC of the electrode plate 100 as necessary (FIG. 16). 16 step S130). When the SOC of electrode plate 100 is adjusted in the SOC adjustment step, control unit 30 performs transient state impedance measurement for one cycle in the transient state impedance measurement step (step S131 in FIG. 16). Here, one cycle means that the measurement frequency of the alternating current changes in one direction from the start point to the end point from the upper limit value as the start point to the lower limit value as the end point within the measurement frequency range. In the measurement of the transient state impedance, an alternating current for measuring the transient state impedance is applied to the electrode plate 100, and the response voltage is acquired. The alternating current applied at this time is the alternating current shown in the graph L31 of FIG. 17A, and the alternating current having a magnitude smaller than the direct current is superimposed while discharging the direct current with a predetermined amount of current. It is a current, and the response voltage is obtained as a voltage shown in a graph L32 in FIG. Specifically, the graph L32 is obtained as a voltage in which the electrode plate 100 is discharged with a predetermined amount of direct current and drops in voltage, and a response voltage with respect to the alternating current for measurement is superimposed.

  As shown in FIG. 16, in the transient impedance measurement step (step S131 in FIG. 16), when one cycle of the measurement frequency is completed, it is determined whether or not to execute the next cycle (step S132 in FIG. 16). The cycle can be repeated until the electrode plate 100 approaches the target SOC.

  When it is determined that the next cycle is to be executed (YES in step S132 in FIG. 16), the control unit 30 moves the process to step S131 in FIG. 16 and executes a transient state impedance measurement process (one cycle).

  On the other hand, when it is determined that the next cycle is not to be executed (NO in step S132 in FIG. 16), the control unit 30 causes the resistance component measurement unit 13 to acquire the impedance of the transient state by charging the charging electric quantity at the measurement point. A second SOC adjustment process for adjusting to the previous charge amount is performed (step S230 in FIG. 16). In the second SOC adjustment step, the transient state impedance measurement unit 43 returns the amount of charge electricity at the measurement point to the original state via the resistance component measurement unit 13, thereby charging the charge amount at the measurement point by measuring the transient state impedance. This reduces the possibility that the change in the above will affect the measurement result of the next measurement point.

Further, the control unit 30 performs a Nyquist diagram creation process in the Nyquist diagram creation unit 44 (steps S133 to S136 in FIG. 16).
More specifically, in the Nyquist diagram creation process, the control unit 30 performs a Nyquist diagram creation step (two-dimensional) (step S133 in FIG. 16) and a Nyquist diagram creation step for adding a time axis (time axis addition). (Step S134 in FIG. 16) and a Nyquist diagram creation step (SOC axis conversion) (Step S135 in FIG. 16) for converting the time axis into the SOC axis are executed. Further, the control unit 30 selects a specific SOC from the SOCs whose equilibrium state impedance has been measured, and estimates a impedance curve corresponding to the selected specific SOC (same SOC estimation) (FIG. 16). Step S136) is executed.

  As shown in FIG. 18, in the Nyquist diagram creation step (two-dimensional) (step S133 in FIG. 16), the control unit 30 creates one Nyquist diagram for each cycle. For example, the impedance curve L41 in FIG. 18 is a Nyquist diagram of a cycle starting from time t0 (see FIG. 19), and the impedance curve L42 is a Nyquist diagram of a cycle starting from time t8 (see FIG. 19). . In the range between the impedance curve L41 and the impedance curve L42, Nyquist diagrams of cycles started from the times t1 to t7 are arranged.

  As shown in FIG. 19, in the Nyquist diagram creation step (time axis addition) (step S134 in FIG. 16), the control unit 30 adds a time axis orthogonal to the real and imaginary axes in the Nyquist diagram shown in FIG. To represent the Nyquist diagram in three dimensions. In one cycle, since it takes time until the measurement frequency moves from the upper limit value to the lower limit value, the Nyquist diagrams L51 to L59 are graphs that move in the direction in which time elapses as the frequency decreases. In FIG. 19, the curve curves upward. The Nyquist diagram L50 is an example in the case where the passage of time is not considered.

  As shown in FIG. 20, the control unit 30 converts the time axis into the SOC axis in the Nyquist diagram creation step (SOC axis conversion) (step S135 in FIG. 16). The SOC of the electrode plate 100 is calculated by subtracting the amount of electric current calculated from the discharge amount of the direct current from the time t0 and the SOC of the electrode plate 100 at the time t0 at the start of measurement is the value c0. The Therefore, the SOC value (for example, values c0 to c8) that changes with the amount of discharge electricity can be associated with the time axis of the Nyquist diagram of FIG. At this time, the impedance corresponding to the unmeasured SOC is estimated by complementing between the Nyquist diagrams L51 to L59.

  As shown in FIG. 21, in the Nyquist diagram creation step (same SOC estimation) (step S136 in FIG. 16), the control unit 30 creates a Nyquist diagram L6 corresponding to the transient response impedance when the SOC is constant. Then, a Nyquist diagram L71 corresponding to a specific SOC to be measured is selected from the created Nyquist diagram L6. As a result, the Nyquist diagram L71 of a specific SOC can be obtained from the transient impedance measured from the transient electrode plate 100 in which the SOC changes.

  Then, as shown in FIG. 16, the control unit 30 analyzes the Nyquist diagram estimated for a specific SOC and fits the equivalent circuit GC (see FIG. 15) to each parameter of the equivalent circuit GC. A parameter calculation step of calculating is performed (step S137 in FIG. 16). When the parameter calculation process ends, the control unit 30 ends the transient state impedance acquisition process.

The determination as to whether or not there is the next measurement point Tg (step S16 in FIG. 12) is the same as in the first embodiment.
Next, as shown in FIG. 12, a state determination step (step S171 in FIG. 12) for determining the electrode plate state of the electrode plate 100 is started.

  As shown in FIG. 22, when the state determination step (step S171 in FIG. 12) is started, the control unit 30 selects parameters of the equivalent circuit GC based on the equilibrium state impedance corresponding to the specific SOC (in FIG. 22). Step S140) and parameter selection of the equivalent circuit GC based on the transient impedance (step S141 in FIG. 22) are performed.

  Next, the control unit 30 uses the parameter calculation unit 45 to calculate a resistance component peculiar to the transient state (step S142 in FIG. 22). That is, the control unit 30 calculates the transient state-specific component ΔR3 that is the difference between the value of the resistance R3 of the equivalent circuit GC in the equilibrium state and the value of the resistance R3 of the equivalent circuit GC in the transient state (see FIG. 23).

  Subsequently, in the determination unit 48, the control unit 30 performs state determination processing for determining deterioration of the electrode plate state (step S143 in FIG. 22). In the state determination process, it is determined that the electrode plate 100 has deteriorated if the calculated transient state-specific component ΔR3 is equal to or greater than the determination threshold set as the deterioration index of the electrode plate 100, and if it is less than the determination threshold, the electrode It is determined that the plate 100 has not deteriorated.

  In the electrode plate map creating step (step S18 in FIG. 12), the control unit 14 associates the deterioration determination result based on the transient state-specific component with respect to the measurement point Tg of the electrode plate 100 for each area of the measurement window. A distribution map of deterioration at 100 is created. Since the distribution map can be used to find a defective part, it is possible to analyze the cause of the defect from the position and tendency of the defect.

The procedure of the electrode plate state determination process is thus completed.
Next, the effect of this embodiment will be described.
(2-1) The transient state-specific component indicating the electrode plate state resulting from the measurement point Tg of the electrode plate 100 being in the transient state can be calculated based on the impedance in the transient state and the impedance in the equilibrium state. At the same time, the measurement point Tg after the measurement can be returned to the charge state before the measurement. By returning to the original state, the transient state-specific components at other measurement points Tg can be appropriately measured, and the distribution of the transient state-specific components can be obtained for the entire electrode plate 100. Therefore, the electrode plate state in the transient state of the electrode plate 100 of the secondary battery can be measured based on the impedance measurement. In addition, the measurement of a transient state specific component may be performed at the time of charge, and may be performed at the time of discharge.

  (2-2) Electrochemical phenomenon due to the behavior of the active material particles in one particle, that is, the transient characteristics of the active material itself, by reducing the opening diameter (diameter WD) of the probe 11 to the particle size level of the active material particles. Can be measured.

(2-3) It is easy to calculate the change in the amount of charge on the electrode plate by making the direct current a rectangular wave.
(2-4) The battery state can be determined by comparing the transient state-specific component with a determination threshold that can measure the deterioration of the electrode plate 100.

  (2-5) Since the measurement frequency changes from the start point (upper limit value) to the end point (lower limit value), it is easy to grasp the continuous frequency characteristics. Moreover, it is easy to generate and measure as a measurement frequency. Further, the impedance in the transient state can be measured by repeating the measurement frequency at an interval that is shorter than the response period in which the electrode plate 100 is in the transient state, for example, 10 seconds.

  (2-6) By setting the upper limit value to 10 kHz or less and the lower limit value to 1 Hz or more, the impedance of the same frequency can be measured multiple times while the electrode plate 100 is in a transient state. As a result, the impedance in the transient state when the electrode plate 100 is in the transient state can be measured for each change in the amount of charge in the electrode plate 100.

  (2-7) When the magnitude of the amplitude of the alternating current is, for example, 2 times, 10 times, or 25 times or more, the electrode plate can be brought into a transient state by the direct current, and the transient state of the electrode plate is brought about. Transient impedance can be measured with an unaffected alternating current.

  (2-8) Difference between mutually corresponding resistance components (for example, the value of the resistance R3) of the resistance component of the equivalent circuit GC in the transient state and the resistance component of the equivalent circuit GC in the equilibrium state. Calculated as (transient state-specific component ΔR3). Thereby, the factor resulting from an equilibrium state can be reduced and the electrode plate state in a transient state can be extracted and measured.

  (2-9) Since the SOC of the electrode plate 100 is a specific SOC, the resistance component of the equivalent circuit GC in the transient state and the resistance component of the equivalent circuit GC in the equilibrium state are targeted. Can be suitably calculated.

  (2-10) The transient impedance at a frequency that cannot be measured with a specific SOC can be estimated from the transient impedance measured while the SOC of the electrode plate 100 changes due to charging or discharging. Therefore, the accuracy of the resistance component of the equivalent circuit GC obtained by fitting can be increased.

(Other embodiments)
In addition, each said embodiment can be changed and implemented as follows. The above embodiments and the following modifications can be implemented in combination with each other within a technically consistent range.

  In the second embodiment, the electrical property pass / fail judgment process is performed using the probe 11 whose measurement window size (diameter WD) is not more than twice the particle size of the active material particles (about 5 μm). The case where is performed is illustrated. However, the present invention is not limited to this, and a probe having a measurement window whose size is twice or less the particle diameter is used as the first probe, and a probe whose area is twice or more larger than the first probe is used as the second probe. Good. For example, the second probe may have a measurement window diameter of about 7.2 μm, about 100 μm, or about 1 mm. The measurement unit 118 may be capable of changing the area of the measurement window of the probe with a diaphragm mechanism or the like. Also good.

  Here, the process when the electrode plate inspection apparatus 120 can measure the transient state-specific component of the electrode plate with two measurement windows will be described. First, the electrode plate inspection apparatus 120 roughly determines a defective portion on the electrode plate by performing an electrode plate state determination process (see FIG. 12) on the entire electrode plate with the second probe. Next, the electrode plate inspection apparatus 120 performs an electrode plate state determination process (see FIG. 12) on the defective portion roughly determined by the first probe, thereby identifying the defective portion on the electrode plate at the active material particle level. Judge with.

  As a result, the measurement range narrowed down by the second probe having a large measurement window area can be measured by the first probe having a small measurement window area, and measurement using the first probe having a small measurement area is required. It will be possible to do quickly in places.

  In the second embodiment, the case where the measurement point is moved after performing the equilibrium state impedance acquisition step and the transient state impedance acquisition step has been described. However, the present invention is not limited to this, and the equilibrium state impedance acquisition step may be performed while moving the measurement point, and then the transient state impedance acquisition step may be performed while moving the measurement point.

  In addition, when performing an equilibrium state impedance acquisition process while moving a measurement point, it does not adjust the SOC of the electrode plate at each measurement point, but the electrode after measuring all the measurement points on the electrode plate adjusted to one SOC. You may make it measure by adjusting a board to the following SOC.

In the second embodiment, the measurement unit 118 may be able to change the area of the measurement window with a diaphragm mechanism or the like, or may switch probes having different measurement window areas.
In the second embodiment, the case where the transient state impedance is measured after measuring the balanced state impedance is exemplified. However, the present invention is not limited to this, and the transient state impedance is measured and then the balanced state impedance is measured. Alternatively, the transient state impedance and the equilibrium state impedance may be measured alternately.

  In the second embodiment, the case where the equivalent circuit GC having the configuration shown in FIG. 15 is set is illustrated. However, the present invention is not limited to this, and the equivalent circuit only needs to have a configuration that can model the battery based on the impedance.

  In each of the above embodiments, the electrode plate map creation step (step S18 in FIG. 3 or FIG. 12) is performed after the electrode plate pass / fail determination step (step S17 in FIG. 3) or the electrode plate state determination step (step S171 in FIG. 12). However, the electrode plate map creation process may be performed simultaneously with the electrode plate quality determination process or may be performed before the electrode plate quality determination process.

  In each of the above embodiments, if the quality of the electrode plate 100 is determined, the electrode plate map creation step (step S18 in FIG. 3 or FIG. 12) may be omitted. That is, the electrode plate map need not be explicitly created.

  In the first embodiment, the measurement unit 118 has been illustrated as having a plurality of measurement window areas. However, the measurement unit 118 may include only one area capable of measuring the state in the depth direction.

  In the first embodiment, the measurement unit 118 has been exemplified for the case where the area of the measurement window can be changed by a diaphragm mechanism or the like. However, the measurement unit 118 is not limited to this, and the measurement unit 118 can be switched for each measurement window area or measured. Probes with different window areas may be switched.

  In each of the above embodiments, the case where charging is performed with the amount of charge so that the voltage at the measurement point Tg becomes the voltage before the start of discharge after discharging has been illustrated, but the present invention is not limited thereto. If the charge state at the measurement point becomes the same by charging / discharging the amount, the voltage need not be confirmed, or it may be confirmed by the current value, the resistance value, or the like.

  In each of the above embodiments, the case where the impedance of the measurement point Tg is fitted each time it is measured is illustrated. However, the present invention is not limited thereto, and the fitting may be performed after measuring the impedance of all or a plurality of measurement points. Good. As a result, the work can be performed separately for only the measurement process and the fitting process.

  In the first embodiment pair, the processing procedure for determining the quality of the electrical characteristics of the electrode plate 100 is exemplified for the case of performing the quality determination based on impedance and the quality determination based on DC-IR. However, the present invention is not limited to this, and the processing procedure for determining the quality of the electrical characteristics of the electrode plate may not perform the quality determination based on the impedance. For example, you may perform only the quality determination based on DC-IR.

  In each of the above embodiments, the case where the electrode plate 100 is installed in a container filled with the electrolytic solution 106 is illustrated. However, the measurement is not limited thereto, and the measurement may be performed using an electrode plate in which the electrode active material layer is sufficiently impregnated with an electrolyte solution in advance. Alternatively, since the electrode active material layer to be inspected is porous and has a minute gap between the electrode active material and the conductive material particles, the probe including the electrolytic solution is connected to the electrode active material layer. By contact, the electrolytic solution may be immersed in a minute gap in the electrode active material layer.

  -In the said 1st Embodiment, although illustrated about the case where the fitting part 141 was provided, not only this but a fitting part does not need to be provided if it is not necessary to perform determination based on an impedance. .

  In the first embodiment, the resistance component measuring unit 13 is exemplified for measuring DC-IR together with impedance. However, the present invention is not limited to this, and impedance may not be measured as long as DC-IR can be measured. That is, the resistance component measurement unit may be a DC-IR measurement unit.

  In each of the above embodiments, the case where the secondary battery is a lithium ion secondary battery has been illustrated, but the present invention is not limited thereto, and the secondary battery may be another nonaqueous electrolyte secondary battery, An alkaline secondary battery such as a nickel hydride secondary battery or a nickel cadmium secondary battery may be used.

  -The secondary battery may not be mounted on an electric vehicle or a hybrid vehicle. For example, the secondary battery may be mounted on a vehicle such as a gasoline vehicle or a diesel vehicle. In addition, the secondary battery may be used as a power source for a moving body such as a railway, a ship, and an aircraft, a robot, and an electrical product such as an information processing apparatus.

  In each of the above embodiments, the secondary battery may be replaced with a primary battery.

  DESCRIPTION OF SYMBOLS 11 ... Probe, 12 ... Mounting part, 13 ... Resistance component measurement part, 14 ... Control part, 20 ... Electrode plate inspection apparatus, 30 ... Control part, 40 ... Processing part, 41 ... SOC adjustment part, 42 ... Equilibrium state impedance Measurement unit 43 ... Transient state impedance measurement unit 45 ... Parameter calculation unit 48 ... Determination unit 50 ... Storage unit 51 ... Parameter 52 ... Determination data 100 ... Electrode plate 102 ... Electrode active material layer 104 DESCRIPTION OF SYMBOLS ... Current collector, 106 ... Electrolyte, 108 ... Mounting table, 112 ... Probe body, 114 ... Counter electrode, 116 ... Electrolyte, 118 ... Measuring part, 120 ... Electrode plate inspection apparatus, 141 ... Fitting part, 142 ... DC resistance Distribution calculation unit, 143: pass / fail judgment unit, C1: capacitance, C2: capacitance, GC: equivalent circuit, L1: inductance, R1: resistance, R2: resistance, R3: resistance, Wo1: diffusion resistance.

Claims (16)

An electrode plate holding part for holding the electrode plate of the secondary battery in the electrolyte solution;
A probe having a counter electrode in the electrolyte in a container having a measurement window opened toward the electrode plate;
A measurement unit connected to the electrode plate and the counter electrode to measure an internal resistance value (DC-IR) for direct current between the electrode plate and the counter electrode;
A moving unit for moving the probe relative to the electrode plate;
The moving unit sequentially moves the probe to different measurement points,
In order to measure the internal resistance value at each measurement point, the measuring unit discharges after charging and returns to the amount of electricity before charging, or charges after discharging. An electrode plate inspection device for returning to the amount of electricity before the discharge. The measurement unit obtains direct currents at different measurement points, respectively.
The electrode plate inspection apparatus according to claim 1, further comprising a determination unit that determines a state related to the current of the electrode plate by comparing the direct current acquired between the different measurement points. The probe can be selected from a plurality of areas opening area of the measurement window,
The electrode plate inspection apparatus according to claim 1, wherein the measurement unit performs measurement of the internal resistance value at the measurement point for each open area of the measurement window. The electrode plate inspection apparatus according to claim 1, wherein the probe has a variable opening area of the measurement window. When discharging after performing the charging, the charging voltage and the discharging voltage applied to the measurement point are made different, or when charging after performing the discharging, the discharging voltage and the charging voltage applied to the measuring point. The electrode plate inspection apparatus according to any one of claims 1 to 4. When discharging after performing the charging, charging is performed so that the voltage at the measurement point is the same before and after the charging, or after performing the discharging. The amount of electricity to be charged and the amount of electricity to be discharged are adjusted so that the voltage at the measurement point becomes the same voltage before the discharge and after the charge. The electrode plate inspection apparatus according to any one of the above. The measurement unit measures complex impedance together,
A fitting unit for fitting the complex impedance to a characteristic model of a secondary battery;
A calculation unit that calculates DC-IR based on a characteristic model of the electrode plate,
The fitting unit adopts a fitting result for a measurement point adjacent to the measurement point as an initial value given to the characteristic model of the electrode plate when fitting the complex impedance of the measurement point to the characteristic model of the electrode plate;
The electrode according to any one of claims 1 to 6, wherein the calculation unit calculates a DC-IR based on the fitting result and compares the measured DC-IR with the calculated DC-IR. Board inspection device. A method for inspecting an electrode plate with an electrode plate inspection device,
An electrode plate holding part for holding the electrode plate of the secondary battery in the electrolyte, a probe having a counter electrode in the electrolyte in a container having a measurement window opened toward the electrode plate, and the electrode plate A measuring unit connected to the counter electrode for measuring an internal resistance value (DC-IR) with respect to a direct current between the electrode plate and the counter electrode; and a moving unit for moving the probe relative to the electrode plate. Used for electrode plate inspection equipment
A moving step in which the moving unit sequentially moves the probe to different measurement points;
In order to measure the internal resistance value at each measurement point, the measurement unit performs a step of discharging after charging and returning to the amount of electricity before the charging, or charging after discharging. And a measuring step having a step of returning to the amount of electricity before performing the discharge. An electrode plate holding part for holding the electrode plate of the secondary battery in the electrolyte solution;
A first adjustment unit that adjusts the charge electricity amount of the electrode plate to a predetermined charge electricity amount by discharging or charging;
A probe having a counter electrode in the electrolyte in a container having a measurement window opened toward the electrode plate;
A moving unit for moving the probe relative to the electrode plate so as to sequentially arrange the probes at different measurement points of the electrode plate;
A measurement frequency that is connected to the electrode plate and the counter electrode and that changes a predetermined frequency range defined by an upper limit value and a lower limit value while maintaining the amount of electric charge of the electrode plate for each measurement point. An equilibrium state impedance acquisition unit that acquires an impedance in an equilibrium state corresponding to the measurement frequency by applying an alternating current to the electrode plate;
The alternating current having the measurement frequency is connected to the electrode plate while being connected to the electrode plate and the counter electrode and changing the amount of charge of the electrode plate by charging or discharging the direct current at each measurement point. A transient state impedance acquisition unit that acquires the impedance of the transient state corresponding to the amount of charged electricity that changes by applying,
A second adjustment unit that adjusts the charge electricity amount at the measurement point to the charge electricity amount before obtaining the impedance in the transient state by discharging or charging; and
An electrode plate comprising: an electrode plate state calculated based on the impedance in the transient state; and a specific component calculation unit that calculates a transient state specific component based on the electrode plate state calculated based on the impedance in the equilibrium state. Inspection device. The electrode plate inspection apparatus according to claim 9, wherein an opening diameter of the measurement window of the probe is not more than twice a particle diameter of active material particles of the electrode plate. The probe is a first probe;
A second probe having an area twice or more that of the first probe;
The electrode plate inspection apparatus according to claim 9 or 10, wherein a portion of the electrode plate determined to be deteriorated by measurement by the second probe is measured by the first probe. The electrode plate inspection apparatus according to claim 9, wherein the DC impedance is a rectangular wave in the transient state impedance acquisition unit. 13. A determination step of determining an electrode plate state of the electrode plate by comparing the transient state-specific component with a determination threshold value that is a value capable of determining deterioration of the electrode plate. The electrode plate inspection apparatus according to item. The transient state impedance acquisition unit sets the measurement frequency from the start point to the end point when one of a lower limit value and an upper limit value defining the predetermined frequency range is set as a start point and the other value is set as an end point. And changing the direction to return to the value of the start point in response to reaching the value of the end point, changing the start point to the end point in less than 10 seconds, and from the end point to the start point The electrode plate inspection apparatus according to any one of claims 9 to 13, wherein the time is returned in a time of 10 seconds or less. The characteristic component calculation unit fits the impedance in the transient state to an equivalent circuit to obtain the equivalent circuit in the transient state corresponding to the electrode plate in the transient state, and converts the impedance in the equilibrium state into an equivalent circuit. Fitting to obtain the equivalent circuit in the equilibrium state corresponding to the electrode plate in the equilibrium state, and the resistance component of the equivalent circuit in the transient state and the resistance component of the equivalent circuit in the equilibrium state The electrode plate inspection apparatus according to claim 9, wherein a difference between resistance components corresponding to each other is calculated as the transient state-specific component. A method for inspecting an electrode plate with an electrode plate inspection device,
An electrode plate holding unit for holding the electrode plate of the secondary battery in the electrolyte, a first adjustment unit for adjusting the charge electricity amount of the electrode plate to a predetermined charge amount by discharging or charging, and the electrode plate A probe having a counter electrode in an electrolyte solution in a container having a measurement window that is open to face, and a moving unit that moves the probe relative to the electrode plate so that the probes are sequentially arranged at different measurement points of the electrode plate. And a measurement unit that is connected to the electrode plate and the counter electrode and measures impedance with respect to the alternating current between the electrode plate and the counter electrode, and is used in an electrode plate inspection apparatus comprising:
An alternating current having a measurement frequency that changes a predetermined frequency range defined by an upper limit value and a lower limit value while maintaining a charge electricity amount of the electrode plate at each measurement point in the measurement unit. An equilibrium state impedance acquisition step of acquiring an impedance in an equilibrium state corresponding to the measurement frequency by applying to
Charging that changes by applying the alternating current having the measurement frequency to the electrode plate while changing the amount of charge of the electrode plate by charging or discharging direct current at each measurement point in the measurement unit A transient state impedance acquisition step of acquiring a transient state impedance corresponding to the amount of electricity;
In the second adjustment unit, an adjustment step of adjusting the charge electricity amount at the measurement point to the charge electricity amount before acquiring the transient impedance by discharging or charging; and
An electrode plate comprising: an electrode plate state calculated based on the impedance in the transient state; and a specific component calculation step for calculating a transient state specific component based on the electrode plate state calculated based on the impedance in the equilibrium state. Inspection method.