State measuring device, state measuring method, and recording medium

Abstract

A state measuring device includes an electrode that applies an alternating current signal to a mixed solution; a measurement unit that measures an impedance of the mixed solution for each frequency of the alternating current signal based on a response signal flowing in the mixed solution when the alternating current signal is applied; a setting unit that sets an equivalent circuit including one or more parallel circuits based on an element corresponding to an electrical component of a solid substance; a calculation unit that performs equivalent circuit analysis for approximating the impedance of the equivalent circuit to the impedance of the mixed solution to calculate parameters of the parallel circuits; and an inference unit that infers an index for determining a state of the mixed solution based on the parameters of the parallel circuits.

Description

TECHNICAL FIELD

[0001] The present application relates to a state measuring apparatus, a state measuring method, and a recording medium recording a program for causing a computer to execute measurement of a state of a mixed liquid in which an insoluble solid substance is mixed in a liquid. BACKGROUND

[0002] In the industrial field, a mixed liquid in which a solid substance having a particle shape of insolubility is mixed is used, for example, for the purpose of creation of a new function realized by compounding substances having different properties, change in shape of a substance, miniaturization or molding, and the like.

[0003] For example, in the field of electronic components and the like, in recent years, the demand for high functionality / high performance is increasing. Therefore, the quality of the mixed liquid for electronic components is also required to be strictly managed based on a specific evaluation index.

[0004] As one of methods of measuring the particle size distribution of particles contained in a mixed liquid, a sedimentation method is known. In the sedimentation method, there are a liquid phase gravity sedimentation method using natural gravity (Japanese Industrial Standard JIS Z8820-1:2002) and a liquid phase centrifugal sedimentation method using centrifugal force (Japanese Industrial Standard JIS Z8823-1:2001).

[0005] In the sedimentation test according to the above-described sedimentation method, the mixed liquid is poured into a sedimentation tube, and the measurer observes changes in the interface height of the particle layer and the supernatant liquid, whether the supernatant liquid is transparent or turbid, and the like as time elapses. Then, the particle size distribution of the mixed liquid is measured based on these changes. SUMMARY

[0006] In the above-described sedimentation test, time is required until the sedimentation of the particles in the mixed liquid is stabilized, and in addition, the measurer needs to observe the mixed liquid. Therefore, for the measurer, it is a complicated job to obtain an index for determining the state of the mixed liquid, and it is not easy.

[0007] The present application is completed in view of the above-described problems, and aims to easily derive an index for determining the state of a mixed liquid.

[0008] The state measurement device according to one aspect of the present application is a state measurement device that measures a state of a mixed liquid in which an insoluble solid substance is mixed in a liquid, and includes: an electrode that applies an alternating current signal to the mixed liquid; a measurement unit that measures an impedance of the mixed liquid for each frequency of the alternating current signal based on a response signal flowing in the mixed liquid when the alternating current signal is applied; a setting unit that sets an equivalent circuit including one or more parallel circuits based on an element corresponding to an electric component of the solid substance; a calculation unit that performs equivalent circuit analysis for approximating the impedance of the equivalent circuit to the impedance of the mixed liquid to calculate parameters of the parallel circuits; and a derivation unit that derives an index for determining the state of the mixed liquid based on the parameters of the parallel circuits.

[0009] According to the aspect of the present application, the index for determining the state of the mixed liquid is derived using the equivalent circuit including the parallel circuit based on the element corresponding to the electric component of the solid substance, based on the measured impedance of the mixed liquid, and thus the index for determining the state of the mixed liquid can be easily derived. BRIEF DESCRIPTION OF DRAWINGS

[0010] Figure 1 is a diagram showing the structure of the state measurement device according to the embodiment of the present application.

[0011] Figure 2 is a block diagram showing the functional configuration of the processing section in the measurement device main body.

[0012] Figure 3A is a diagram for explaining the impedance complex plane diagram made in the complex plane impedance data generation module and the equivalent circuit analysis module.

[0013] Figure 3B is a diagram for explaining the equivalent circuit used for the equivalent circuit analysis.

[0014] Figure 4 is a conceptual diagram for explaining the equivalent circuit analysis performed in the state measurement device according to the embodiment.

[0015] Figure 5 is a diagram showing a model using a two-dimensional grid to represent the concept shown in Figure 4

[0016] Figure 6 is a diagram for explaining one example of the equivalent circuit representing the model shown in Figure 5

[0017] Figure 7 is a flowchart showing the state measurement processing performed by the state measurement device.

[0018] Figure 8 ​​It is used to represent Figure 5 The diagram illustrates a first variation of the equivalent circuit of the model shown.

[0019] Figure 9 This is a graph showing the relationship between the relaxation time τ and the resistance value R, generated by the derivation module.

[0020] Figure 10 It is used to represent Figure 5 The diagram illustrates a second variation of the equivalent circuit of the model shown.

[0021] Figure 11 It is a graph showing the correspondence between the resistance value R generated by the derivation module and the frequency of occurrence.

[0022] Figure 12A It is a graph showing the correspondence between the position coordinates i and the frequency of occurrence of R, which is generated by the derivation module.

[0023] Figure 12B It is a graph that uses continuous representation to show the correspondence between the position coordinates i and the frequency of occurrence of R, which is generated by the derivation module.

[0024] Figure 13 It is a plot that shows the conductivity as a function of stirring time.

[0025] Figure 14 This is a graph showing the uniformity as a function of stirring time.

[0026] Figure 15 This is a schematic diagram used to illustrate the state of a slurry with good uniformity and conductivity.

[0027] Figure 16 This is a schematic diagram used to illustrate the state of a slurry with poor uniformity but good electrical conductivity.

[0028] Figure 17 This is a schematic diagram used to illustrate the state of a slurry with good uniformity but poor conductivity.

[0029] Figure 18 This is a schematic diagram used to illustrate the state of a slurry with poor uniformity and conductivity.

[0030] Explanation of reference numerals in the attached figures:

[0031] 1: Uniformity measuring device; 2: Electrode; 3: Measuring device body; 31: Measuring section; 32: Storage section; 33: Operation section; 34: Display section; 35: Processing section; 111: Analysis setting module; 112: Impedance acquisition module; 113: Complex plane impedance data generation module; 114: Equivalent circuit analysis module; 115: Derivation module; 121: Setting section; 122: Parameter calculation section. DETAILED DESCRIPTION

[0032] [Explanation of the state measuring device]

[0033] By using Figure 1 and Figure 2 The state measuring device 1 according to an embodiment of the present application will be described in detail.

[0034] Figure 1 is a schematic diagram showing the structure of the state measuring device 1 according to the present embodiment.

[0035] The state measuring device 1 is a device for evaluating a slurry Xc which is one of the mixed solutions stored in a liquid tank X. The slurry Xc is a slurry in which an insoluble solid substance Xb (hereinafter, referred to as an active substance Xb) is mixed in a liquid Xa.

[0036] In the present embodiment, as one example, the slurry Xc is a slurry for a positive electrode or a negative electrode of a lithium ion battery. In the present embodiment, the slurry Xc is a slurry in which a conductive aid C having high conductivity is dispersed in a solvent containing a binder resin B and the active substance Xb.

[0037] That is, in the slurry Xc, the active substance Xb, the binder resin B, and the conductive aid C are contained as the solid substance. Note that, in general, the order of the conductivity is the conductive aid C > the active substance Xb > the binder resin B.

[0038] The state measuring device 1 applies an alternating current signal to the slurry Xc, and at this time, the impedance of the slurry Xc is measured based on a response signal flowing in the slurry Xc. Further, the state measuring device 1 sets an equivalent circuit of the slurry Xc, performs equivalent circuit analysis so that the impedance of the equivalent circuit is close to the measurement result, and thereby derives the state of the slurry Xc. The state of the slurry Xc derived in the present embodiment is a physical property and an electrical property.

[0039] The state measuring device 1 includes an electrode 2 and a measuring device main body 3.

[0040] The electrode 2 is an electrode for applying an alternating voltage as an alternating current signal to the slurry Xc stored in the liquid tank X, and includes a pair. The pair of electrodes 2 is provided in the peripheral wall of the liquid tank X in a manner of facing each other. The electrode 2 is formed of, for example, an inert metal such as platinum or copper. A response current as a response signal corresponding to the alternating voltage applied to the slurry Xc flows between the pair of electrodes 2. Note that the alternating current signal applied to the slurry Xc is not limited to the alternating voltage, and can be an alternating current.

[0041] As Figure 1As shown, the measurement device main body 3 includes a measurement section 31 as a measurement unit, a storage section 32 as a storage unit, an operation section 33, a display section 34, and a processing section 35 as a processing unit.

[0042] The measurement section 31 measures the impedance of the slurry Xc in accordance with a response current flowing when an alternating voltage is applied to the slurry Xc positioned between the pair of electrodes 2. The measurement section 31 applies an alternating voltage whose frequency changes in stages to the pair of electrodes 2. Note that the alternating voltage applied to the pair of electrodes 2 is supplied from a constant voltage power supply (CV) or a constant current power supply (CC) built into the measurement section 31. Also, each time the frequency of the alternating voltage changes in stages, the measurement section 31 measures the impedance in accordance with a response current between the pair of electrodes 2 and outputs the measurement signal to the processing section 35.

[0043] The storage section 32 is constituted by a random access memory (RAM) and a read only memory (ROM). A program for executing a state measurement process for deriving an index for determining the state of the slurry Xc is stored in the storage section 32. That is, the storage section 32 is a computer-readable storage medium in which a program for the operation of the processing section 35 is recorded. The storage section 32 can be configured to be detachable with respect to the measurement device main body 3.

[0044] Further, a frequency characteristic table regarding the slurry Xc whose state is known is stored in the storage section 32. In the frequency characteristic table, a correspondence relationship between the frequency of the alternating voltage and the measured value of the impedance when the alternating voltage is applied is shown. Specifically, the measured value of the impedance corresponding to the alternating voltage applied to the slurry Xc whose state is known and the frequency of the alternating voltage are associated and stored as the frequency characteristic table.

[0045] The operation section 33 is provided with various operation switches for instructing the setting operation of the measurement conditions and the start of the state measurement process and the like. The operation section 33 outputs operation signals corresponding to these operations to the processing section 35. The operation section 33 can also be a touch panel formed on the display section 34, thereby replacing the operation switches configured mechanically.

[0046] The display section 34 displays various setting screens for the state measurement of the slurry Xc, measurement results, and the like in accordance with the instructions of the processing section 35. In the present embodiment, the display section 34 is constituted by a liquid crystal panel or the like.

[0047] The processing section 35 controls each section constituting the state measurement device 1 in accordance with the operation signals from the operation section 33. Further, the processing section 35 controls the frequency of the alternating voltage applied to the pair of electrodes 2 and acquires the impedance corresponding to the applied alternating voltage. Further, the processing section 35 executes a process for deriving an index for determining the state of the slurry Xc based on the acquired impedance.

[0048] In the present embodiment, the processing section 35 is constituted by a central processing unit (CPU) as a computer. The processing section 35 can also be constituted by a plurality of microcomputers.

[0049] Next, the functional configuration and operation of the processing section 35 of the measurement device main body 3 will be described.

[0050] Figure 2 is a block diagram showing the functional configuration of the processing section 35 of the measurement device main body 3.

[0051] The processing section 35 has an analysis setting module 111, an impedance acquisition module 112, a complex plane impedance data generation module 113, an equivalent circuit analysis module 114, and a derivation module 115. Hereinafter, the complex plane impedance data generation module 113 will be referred to simply as the generation module 113.

[0052] The analysis setting module 111 generates a control signal for causing the measurement section 31 to execute a process of applying an alternating voltage to the electrode 2 and a process of measuring an impedance.

[0053] The impedance acquisition module 112 acquires the impedance measured by the measurement section 31. The impedance acquisition module 112 in the present embodiment generates measured data showing the imaginary component and the real component of the impedance from the impedance based on the response current of the slurry Xc transmitted from the measurement section 31, and outputs the measured data to the generation module 113.

[0054] The generation module 113 creates data showing the complex plane impedance from the measured data showing the imaginary part and the real part of the impedance acquired by the impedance acquisition module 112 for each frequency of the alternating voltage.

[0055] In the present embodiment, the generation module 113 creates an impedance complex plane plot in which the imaginary part of the measured impedance is set as the vertical axis and the real part is set as the horizontal axis, as the data showing the complex plane impedance. Note that the impedance complex plane plot is sometimes referred to as a Nyquist diagram.

[0056] The generation module 113 outputs the impedance complex plane plot created to the equivalent circuit analysis module 114.

[0057] The equivalent circuit analysis module 114 performs equivalent circuit analysis using an equivalent circuit in which elements such as a resistor and a capacitor are combined.

[0058] The equivalent circuit analysis module 114 has a setting section 121 and a parameter calculation section 122.

[0059] The setting section 121 sets an equivalent circuit based on an electric resistance component (impedance) possessed by each of the electric component solid substances (the active material Xb, the binder resin B, and the conductive aid C) as the solid substances. In the present embodiment, a direct current resistance component and a capacitance component (an alternating current resistance component) are also included in the electric resistance component.

[0060] The setting section 121 can set a component of at least one of an internal resistance component of the solid substances (the active material Xb, the binder resin B, and the conductive aid C) and a contact resistance component of the solid substances with each other as the electric resistance component. In the present embodiment, the setting section 121 sets an equivalent circuit including a series circuit of a parallel circuit corresponding to the internal resistance component of the solid substances and a parallel circuit corresponding to the contact resistance component of the solid substances with each other.

[0061] The setting section 121 sets an equivalent circuit as a parallel circuit, which is configured by connecting at least either one of a parallel circuit of a resistor and a capacitor (R-C) and a parallel circuit of a resistor and a constant phase element (hereinafter, referred to as CPE) (R-CPE).

[0062] In a case where a plurality of solid substances are mixed in the slurry Xc, the setting section 121 sets a parallel circuit corresponding to the internal resistance component of the solid substances and a contact resistance component of each combination of mutually different solid substances in accordance with the different solid substances.

[0063] That is, in the equivalent circuit of the slurry Xc, the setting section 121 sets a parallel circuit corresponding to the internal resistance component of the active material Xb as the first solid substance, a parallel circuit corresponding to the contact resistance component of the active material Xb with each other, a parallel circuit corresponding to the internal resistance component of the binder resin B as the second solid substance, a parallel circuit corresponding to the contact resistance component of the binder resin B with each other, and a parallel circuit corresponding to the contact resistance component of the active material Xb and the binder resin B.

[0064] Further, the setting section 121 can also set the same parallel circuit between the active material Xb and the conductive aid C and between the binder resin B and the conductive aid C.

[0065] In the present embodiment, the equivalent circuit of the slurry Xc is set based on the resistance components possessed by each of the active material Xb, the binder resin B, and the conductive aid C. The resistance components referred to here include the internal resistance components of each of the active material Xb, the binder resin B, and the conductive aid C, the contact resistance components of the same substances with each other, and the contact resistance components of mutually different substances. In the case where the number of fixed substances is three, the upper limit of the total number of resistance components, i.e., the upper limit of the total number of parallel circuits set in the equivalent circuit, is nine.

[0066] The setting section 121 can set the number of parallel circuits to be equal to or less than the total number of resistance components of the solid substances, according to the accuracy of the required derivation result. Note that the number of parallel circuits can also be limited to the number of resistance components of the solid substances that respond to the applied varying AC voltage within the frequency range of the AC voltage.

[0067] The parameter calculation section 122 performs equivalent circuit analysis for approximating the impedance of the equivalent circuit set in the setting section 121 to the impedance of the mixed solution measured by the measurement section 31, and calculates the parameters of each parallel circuit constituting the set equivalent circuit.

[0068] The calculated parameters of each parallel circuit are the resistance value of a resistor, the electrostatic capacity of a capacitor, the parameters of a constant phase element (CPE), and the like. For example, in the case where an R-C circuit is taken as one element, the parameters of the parallel circuit are the resistance value of the resistor R and the electrostatic capacity of the capacitor C. Further, in the case where an R-CPE circuit is taken as one element, the CPE constant T, the CPE exponent p, and the like described later are included in the parameters of the parallel circuit.

[0069] In the case where a CPE is applied to the equivalent circuit of the slurry Xc, the equivalent circuit analysis module 114 generates initial impedance characteristic data representing the frequency characteristics of the real part and the imaginary part of the impedance in the equivalent circuit, based on the initial parameters in the applied equivalent circuit.

[0070] The equivalent circuit analysis module 114 sequentially changes the parameters of the equivalent circuit so that the generated initial impedance characteristic data approaches the measured data of the impedance of the slurry Xc. The equivalent circuit analysis module 114 outputs the parameters of the equivalent circuit for which impedance characteristic data consistent with the measured data can be obtained as the analysis result. In this way, the equivalent circuit analysis module 114 performs equivalent circuit analysis using the equivalent circuit to which a CPE is applied.

[0071] In the present embodiment, the equivalent circuit analysis module 114 makes an impedance complex plane diagram of the equivalent circuit set in the setting section 121 as the impedance characteristic data.

[0072] It should be noted that a constant phase element (CPE) refers to an element that, relative to a typical capacitor C, incorporates factors that can account for various interferences. The impedance Z of the CPE... CPE It is represented by the following formula (1).

[0073] [Formula 1]

[0074]

[0075] In equation (1) above, j is the imaginary unit, ω is the angular frequency, T is the CPE constant, and p is the CPE exponent (Z). CPE (order).

[0076] As shown in equation (1) above, the impedance Z of the CPE is... CPE It consists of the CPE constant T and the CPE exponent p. For example, in impedance Z... CPE In the case of purely capacitive behavior, the CPE exponent p takes a value in the range of 0 to 1.

[0077] Furthermore, in equation (1) above, when p = 1, the CPE constant T is equivalent to a typical capacitor C. Moreover, the equivalent circuit of the slurry Xc is constructed using a typical capacitor C. Therefore, when p = 1, the impedance Z... CPE This represents the value of C in a typical capacitor.

[0078] Figure 3A This diagram is used to illustrate the impedance complex plane diagrams created in generation module 113 and equivalent circuit analysis module 114. Furthermore, Figure 3B This represents the equivalent circuit C used for equivalent circuit analysis. CPE The image.

[0079] Figure 3A The solid line shown represents the impedance complex plane diagram A, generated by the generation module 113 based on impedance measurement data. The dashed line represents the impedance complex plane diagram B, generated by the equivalent circuit analysis module 114.

[0080] Figure 3B The equivalent circuit C shown CPE One example is the equivalent circuit obtained by connecting the parallel circuit R-CPE1 consisting of resistors R1 and CPE1, the parallel circuit R-CPE2 consisting of resistors R2 and CPE2, and the parallel circuit R-CPE3 consisting of resistors R3 and CPE3 in series.

[0081] Figure 3A Impedance complex plane diagram B in the diagram is used Figure 3B The equivalent circuit C shown CPE Complex impedance diagram obtained by performing equivalent circuit analysis.

[0082] The equivalent circuit analysis module 114 repeatedly changes the parameters associated with the resistor R and the CPE in each parallel circuit of the equivalent circuit C CPE to make the impedance complex plane diagram B overlap the impedance complex plane diagram A.

[0083] The equivalent circuit analysis module 114 acquires the complex impedance diagram generated by the generation module 113 and analyzes it.

[0084] The equivalent circuit analysis module 114 sets the parameters of the circuit elements of the equivalent circuit to make the impedance complex plane diagram B overlap the impedance complex plane diagram A.

[0085] The parameters associated with the resistor R and the CPE when the impedance complex plane diagram B overlaps the impedance complex plane diagram A are output to the derivation module 115.

[0086] The derivation module 115 derives an index for determining the state of the slurry Xc on the basis of the parameters input from the parameter calculation section 122. In the present embodiment, as the index for determining the state of the slurry Xc, there are an electrical characteristic and a physical characteristic. As one example, the electrical characteristic is the electrical conductivity. In addition, the physical characteristic is the uniformity.

[0087] With the above structure, the processing section 35 creates the impedance complex plane diagram A on the basis of the impedance of the slurry Xc measured by the measurement section 31. In addition, the processing section 35 creates the impedance complex plane diagram B using the equivalent circuit in which the parallel circuit composed of the resistor R and the CPE is one element by the equivalent circuit analysis module 114, sets the parameters of the elements of the parallel circuit of the equivalent circuit to make the impedance complex plane diagram B overlap the impedance complex plane diagram A. Then, the processing section 35 derives an index for determining the state of the slurry Xc on the basis of the parameters associated with the resistance value R of the resistor, the static capacity C of the capacitor, and the CPE when the impedance complex plane diagram B overlaps the impedance complex plane diagram A.

[0088] < Equivalent Circuit Analysis and Index Derivation Calculation >

[0089] Next, in the present embodiment, the equivalent circuit analysis performed by the processing section 35 will be described. Figure 4 is a conceptual diagram for describing the equivalent circuit analysis performed in the state measurement device 1.

[0090] In the present embodiment, the slurry Xc is a slurry in which the electrically conductive aid C having high electrical conductivity is dispersed in a solvent containing the binder resin B and the active material Xb.

[0091] In describing the equivalent circuit analysis, first, the model of the slurry Xc introduced in the present embodiment will be described.

[0092] As Figure 4As shown in the slurry Xc, the active material Xb exists as primary particles, or is agglomerated to form secondary particles. Also, the conductive aid C likewise exists as primary particles, or is agglomerated to form secondary particles. Also, it is considered that an electrically conductive path is locally formed by the dispersion state of the active material Xb and the conductive aid C in the solvent containing the binder resin B.

[0093] Figure 5 is a diagram showing a model of the slurry Xc. Figure 4 is a diagram showing a model of the model of the slurry Xc.

[0094] The active material Xb, the binder resin B, and the conductive aid C each have a prescribed internal resistance (impedance), and thus, as shown in Figure 5 , it is possible to represent the active material Xb, the binder resin B, and the conductive aid C by a parallel circuit using a resistor and a capacitor, respectively. Also, the slurry Xc as a whole can be represented as one circuit. Also, it is possible to represent the active material Xb, the binder resin B, and the conductive aid C by a parallel circuit using a resistor, a capacitor, a constant phase element (CPE), or the like, respectively.

[0095] Figure 6 is a diagram for explaining one example of an equivalent circuit of the model shown in Figure 5 .

[0096] Figure 5 The model shown in Figure 6 can be represented as the equivalent circuit shown in Figure 6 . In , one element composed of R11, T11, and p11 represents one of the resistance components of a plurality of certain solid substances, respectively.

[0097] In the present embodiment, the slurry Xc contains the active material Xb, the binder resin B, and the conductive aid C. Therefore, as the resistance components of the solid substances, it is possible to set the internal resistance components of the active material Xb, the binder resin B, and the conductive aid C, and the contact resistance components of the same substances to each other (the active material Xb to each other, the binder resin B to each other, and the conductive aid C to each other) in the equivalent circuit.

[0098] Also, as the contact resistance components between the solid substances, it is possible to set the contact resistance components of the active material Xb and the binder resin B, the contact resistance components of the active material Xb and the conductive aid C, and the contact resistance components of the binder resin B and the conductive aid C.

[0099] In the model shown in Figure 5 , in reality, the current preferentially flows through the conductive path having the lowest resistance value. Therefore, in Figure 6In the equivalent circuit shown, the influence of several elements that constitute the conduction path having the lowest resistance value among many conduction paths becomes a dominant influence. Therefore, for a conduction path in which it is considered that electric conduction and the like is hardly performed, it is sometimes possible to be omitted.

[0100] Figure 6 The equivalent circuit shown can be expressed as a series circuit in which parallel circuits corresponding to specific resistance components among the above-described resistance components are connected in series.

[0101] As one example of such a series circuit, it is possible to set Figure 3B The equivalent circuit C CPE shown.

[0102] In Figure 3B One example of the equivalent circuit shown, a case in which the number of parallel circuits (elements) is three is shown. Here, as shown in Figure 5 The number of parallel circuits (elements) can be determined based on the number of kinds of resistance components of the solid substance that constitutes the slurry Xc. Therefore, the total number of resistance components of the solid substance included in the slurry Xc becomes the upper limit number of parallel circuits that can be set in the equivalent circuit.

[0103] Here, the upper limit value N P of the number of kinds of resistance components max can be expressed by the following formula.

[0104] [Formula 2]

[0105]

[0106] As one example, if the number of kinds of solid substances N M = 2, according to the above formula, the upper limit value N P of the number of kinds of resistance components max becomes N P max = 5. Further, if the number of kinds of solid substances N M = 3, the upper limit value N P of the number of kinds of resistance components max becomes N P max = 9.

[0107] The five components that are the upper limit for the case in which the number of kinds of solid substances is two will be described. Figure 4

[0108] The five components are the impedance (Z1) of the active material Xb, the impedance (Z2) of the conductive aid C, the impedance (Z11) of the interface between the active material Xb and the active material Xb, the impedance (Z12) of the interface between the active material Xb and the conductive aid C, and the impedance (Z22) of the interface between the conductive aid C and the conductive aid C.

[0109] Here, according to Figure 4 , it is considered that the current flowing in the active material Xb is small, and thus the following relation is established between the absolute values of the respective impedances.

[0110] |Z2| << |Z1|, |Z12|, |Z11|

[0111] Further, in a case where the voltage drop caused by |Z22| is small to the extent that it can be ignored compared to |Z2|, the |Z22| component can also not be included as an element. In this case, only the element of |Z2| is considered. Thus, N P max The minimum value of N

[0112] The processing section 35 creates an impedance complex plane plot B based on the equivalent circuit described above, and sets the resistance value R, the CPE constant T, and the CPE exponent p, or the like, which are parameters of the respective elements of the equivalent circuit, so that the impedance complex plane plot B overlaps the impedance complex plane plot A. At times, the static capacitance C is also set instead of the CPE constant T and the CPE exponent p.

[0113] Then, the derivation module 115 derives an index for determining the state of the slurry Xc based on the parameters of the respective elements when the impedance complex plane plot B overlaps the impedance complex plane plot A.

[0114] In the present embodiment, the derivation module 115 derives an index indicating a physical property of the slurry Xc and an index indicating an electrical property as the above-mentioned index.

[0115] As one example of the index indicating a physical property, the uniformity can be cited. The derivation module 115 can derive an index indicating the uniformity of the slurry Xc based on at least any one of the resistance value R of the parallel circuit, the static capacitance C of the capacitor, and the CPE exponent p among the parameters of the equivalent circuit obtained.

[0116] As a specific example, based on the CPE exponent p, an index indicating the uniformity of the slurry can be derived according to the following Formulas P1 to P3.

[0117] [Formula 3]

[0118] u λλ′ = p λλ′ … P1

[0119]

[0120]

[0121] In the above-described Formula P1 to Formula P3, λ is a conduction path of a certain specific current of the slurry Xc, and λ' represents a category of the solid substance and a category of a contact of the solid substance with each other. In the present embodiment, the solid substance is the active material Xb, the binder resin B, and the conductive aid C.

[0122] u λλ’ represents the uniformity of one element of the solid substance. Therefore, in the above-described model, the CPE exponent p represents the uniformity u of the solid substance.

[0123] u λ represents a sum of the uniformity related to a certain solid substance and a contact of the solid substance with each other in a certain conduction path.

[0124] u represents a sum of the uniformity related to a certain solid substance and a contact of the solid substance with each other in a certain conduction path, which is obtained by adding the sums of the uniformity of the respective solid substances included.

[0125] Further, as one example of an index representing an electrical characteristic, there is the electrical conductivity. The derivation module 115 can derive the electrical conductivity of the slurry Xc based on at least any one of the values of the resistance value R of the parallel circuit, the electrostatic capacity C of the capacitor, the CPE constant T, and the CPE exponent p in the parameters of the equivalent circuit obtained.

[0126] That is, an index depending on the direct current resistance of the slurry Xc can be derived from the total of the resistance values R. Further, an index depending on the capacitance of the high frequency limit of the slurry Xc can be derived from the total of the capacitor C or the CPE constant T. Further, the proportion of the resistance of the solid substance of interest with respect to the resistance of the entire slurry Xc can be derived. Further, the proportion of the capacitance of the solid substance of interest with respect to the capacitance of the entire slurry Xc can be derived.

[0127] More specifically, the index representing the electrical characteristic can be derived by the following Formula E1 to Formula E10.

[0128] [Formula 4]

[0129] α λλ′ = R λλ′ …E1

[0130] α λλ′ = T λλ′ …E2

[0131]

[0132]

[0133]

[0134]

[0135] wherein ∈ λλ′ = 0 or 1

[0136] [Equation 5]

[0137]

[0138]

[0139] value in the reference slurry

[0140]

[0141]

[0142] In the above Equations El to E10, λ is a conduction path of a certain specific current of the slurry Xc, and λ' represents a kind of solid substance and a kind of contact of the solid substances to each other. In the present embodiment, the solid substance is the active material Xb, the binder resin B, and the conductive aid C.

[0143] α λλ’ represents the conductivity of the resistance related to the solid substance or the contact λ' in the conduction path λ of interest among the conduction paths of the plurality of currents.

[0144] α represents the sum of the resistances of the slurry Xc.

[0145] α -1 represents the sum of the capacitances of the slurry Xc.

[0146] α λ represents the sum of the resistances in the path λ of interest.

[0147] α λ -1 represents the sum of the capacitances in the path λ.

[0148] Further, the derivation module 115 calculates the relaxation time τ of each element based on the parameters of each element obtained by the equivalent circuit analysis. x calc .

[0149] The present inventors et al. found that there is an inherent relaxation time in each of the solid substance itself, the contact of the same solid substance to each other, and the contact of different solid substances based on the model described above.

[0150] As the expression Figure 5The equivalent circuit of the model shown is obtained by applying... Figure 6 In the case of the equivalent circuit shown, the relaxation time of each element can be calculated using the resistance value R, CPE constant T, and CPE exponent p of the resistors obtained through equivalent circuit analysis, according to the following formula.

[0151] [Formula 6]

[0152]

[0153] As an example, the relaxation time τ of each element is calculated from the measured impedance of slurry Xc using equivalent circuit analysis. x calc The standard relaxation time τ of each element is obtained from a reference slurry with a known state of slurry. λ ref By comparing them, we can determine the impedance value of each element and the type of solid material (the type of interface between solid materials).

[0154] As described above, the state measuring device 1 of this embodiment can derive physical and electrical characteristics based on parameters related to each element obtained by performing equivalent circuit analysis.

[0155] <State Measurement Processing>

[0156] Next, refer to Figure 7 The process of deriving and measuring the physical and electrical properties of the slurry Xc as evaluation indicators is explained.

[0157] Figure 7 This is a flowchart illustrating the state measurement process performed by the state measurement device 1.

[0158] First, when the state measurement process is started by the operator operating the operation unit 33, step S1 is entered.

[0159] In step S1, the analysis setting module 111 of the processing unit 35 instructs the measuring unit 31 to perform voltage application processing on the slurry Xc. Specifically, the analysis setting module 111 instructs the measuring unit 31 to perform a process of applying an AC voltage to the slurry Xc while changing the frequency.

[0160] Therefore, the measuring unit 31 applies an alternating voltage to the slurry Xc via a pair of electrodes 2 according to the instruction from the analysis setting module 111, and performs control to change the frequency of the applied alternating voltage.

[0161] Further, the measuring section 31 measures the impedance of the slurry Xc based on the response current flowing in the slurry Xc through the pair of electrodes 2 each time the frequency of the alternating voltage is changed. Then, the measuring section 31 outputs the measured impedance as measurement data to the impedance acquisition module 112 of the measuring device main body 3.

[0162] Next, in step S2, the impedance acquisition module 112 acquires the measurement data of the impedance from the measuring section 31.

[0163] In step S3, the impedance acquisition module 112 generates the imaginary component and the real component of the impedance. The impedance acquisition module 112 outputs the generated imaginary component and real component to the generation module 113.

[0164] Next, in step S4, the generation module 113 creates the impedance complex plane plot A based on the measurement data of the impedance as shown in FIG. 4, and outputs the created impedance complex plane plot A to the equivalent circuit analysis module 114. Figure 3A

[0165] In step S5, the equivalent circuit analysis module 114 performs equivalent circuit analysis based on the measurement data, sets the number of parallel circuits of the resistor R and the CPE (R-CPE circuit) and the R-CPE circuit constituting the equivalent circuit based on the resistance component of the solid substance contained in the slurry Xc, and calculates the parameters of the equivalent circuit.

[0166] Then, the equivalent circuit analysis module 114 creates the impedance complex plane plot B of the set equivalent circuit.

[0167] For example, in the case where an initial value is required, the equivalent circuit analysis module 114 sets the diameter of the semicircle drawn on the complex plane to R and the frequency of the vertex of the semicircle to f top The initial CPE constant T is set as shown in the following expression (2), and the initial CPE exponent p is set to 1. Then, the equivalent circuit analysis module 114 generates the impedance complex plane plot B of the initial equivalent circuit based on the set values of the CPE constant T and the CPE exponent p.

[0168] [Expression 7]

[0169]

[0170] In step S6, the equivalent circuit analysis module 114 compares the impedance complex plane plot A and the impedance complex plane plot B, and determines whether or not they overlap.

[0171] In the case where the impedance complex plane plot A and the impedance complex plane plot B do not overlap (step S6: No), the process returns to step S5, and the equivalent circuit analysis module 114 re-sets the equivalent circuit C CPE ​parameters (variables) of the circuit elements of the equivalent circuit C

[0172] The equivalent circuit analysis module 114 repeatedly performs setting of parameters associated with the resistor R and the CPE in each parallel circuit of the equivalent circuit C CPE to make the impedance complex plane B overlap the impedance complex plane A acquired from the generation module 113. This is called a fitting process.

[0173] When the impedance complex plane A overlaps the impedance complex plane B (step S6: YES), the equivalent circuit analysis module 114 outputs the finally obtained impedance complex plane B to the derivation module 115.

[0174] In step S7, the derivation module 115 acquires the equivalent circuit parameters (resistance value R, electrostatic capacity C, CPE constant T, and CPE exponent p) related to the impedance complex plane B from the equivalent circuit analysis module 114.

[0175] The derivation module 115 derives an index indicating the physical property of the slurry Xc and an index indicating the electrical property on the basis of the parameters of each element.

[0176] Next, in step S8, the display section 34 displays the electrical property and the physical property of the slurry Xc according to the instruction of the processing section 35. Then, the processing section 35 completes the state measurement processing.

[0177] < State Measurement Program >

[0178] The above-described state measurement method can also be provided as a program for causing a computer to perform measurement of the uniformity.

[0179] That is, the program of the present embodiment is a program for causing a computer to perform measurement of the state of a slurry Xc which is a mixed liquid in which an insoluble solid substance (active material Xb) is mixed in a liquid Xa, and is a program for causing a computer to perform the following processing: an alternating current signal is applied to the slurry Xc while varying the frequency of the alternating current signal, the impedance of the slurry Xc is measured for each frequency of the alternating current signal on the basis of a response signal flowing in the slurry Xc when the alternating current signal is applied to the slurry Xc, an equivalent circuit in which a parallel circuit of a resistor R and a capacitor C or a constant phase element (CPE) is taken as an element corresponding to an internal resistance component of the active material Xb is derived from the measured impedance, equivalent circuit analysis for approximating the impedance of the equivalent circuit to the impedance of the slurry Xc is performed, the parameters of the parallel circuit are calculated, and an index for determining the state of the slurry Xc is derived on the basis of the parameters of the parallel circuit.

[0180] In the present embodiment, the above-described program can be stored in the storage section 32, and can also be provided recorded on a recording medium which can be attached to and detached from the state measurement device 1.

[0181] <Effects>

[0182] Next, the effects of the present embodiment will be described.

[0183] The state measuring device 1 of the present embodiment measures the impedance of the slurry Xc in response to the current flowing in the slurry Xc as a mixed solution, sets an equivalent circuit in which a parallel circuit (R-C / R-CPE) corresponding to the resistance component of the solid substance (the active material Xb, the binder resin B, and the conductive aid C) contained in the slurry Xc is at least one element, and then creates an impedance complex plane diagram B of the set equivalent circuit, performs a fitting process, thereby calculating parameters related to the equivalent circuit, and derives an index for determining the state of the slurry Xc from the obtained parameters of the parallel circuit.

[0184] First, the inventors found that by regarding the parallel circuit (R-C / R-CPE) as the resistance component of the solid substance contained in the mixed solution, the state of the mixed solution can be grasped from the parameters of the parallel circuit (R-C / R-CPE). Therefore, the state measuring device 1 processes the obtained parameters of the parallel circuit as the resistance component of the solid substance contained in the mixed solution when deriving the above index. Thus, the index derived based on the obtained parameters of the parallel circuit changes according to the state change of the solid substance in the mixed solution, and therefore the state of the mixed solution can be determined from the index.

[0185] Therefore, the state measuring device 1 performs the equivalent circuit analysis using the measured data of the impedance of the slurry Xc obtained by applying the current to the slurry Xc, and thereby can easily derive the index for determining the state of the mixed solution.

[0186] In the state measuring device 1, the setting unit 121 sets an equivalent circuit including a series circuit in which a parallel circuit corresponding to the internal resistance component of the solid substance and a parallel circuit corresponding to the contact resistance component between the solid substances are connected in series. Thus, the state measuring device 1 can improve the accuracy of the equivalent circuit analysis by taking into account not only the internal resistance component of the solid substance but also the contact resistance component.

[0187] In the state measuring device 1, in the case where a plurality of solid substances are mixed in the slurry Xc, the setting unit 121 sets a parallel circuit corresponding to the internal resistance component of each of the plurality of solid substances, a parallel circuit corresponding to the contact resistance component between the same solid substances, and a parallel circuit corresponding to the contact resistance component between different solid substances. Thus, even in the case of a liquid in which a plurality of solid substances are mixed, the state measuring device 1 can easily derive the index for determining the state of the mixed solution.

[0188] Furthermore, the setting unit 121 can set the number of the aforementioned parallel circuits (elements) to be less than or equal to the total number of all resistive components of the solid material. Therefore, the number of elements for equivalent circuit analysis can be made appropriate, reducing the computational load.

[0189] As shown in equations P1 to P3 and E1 to E10 above, the derivation module 115 derives an index for determining the state of the mixture based on the value obtained by combining at least one of the following parameters in a parallel circuit corresponding to the internal resistance components or contact resistance components of multiple solid substances: the resistance value R of the resistor, the capacitance C of the capacitor, the CPE constant T, and the CPE exponent p. Therefore, the state of the mixture can be easily obtained using the state measuring device 1.

[0190] According to the state measuring device 1, the uniformity of slurry Xc can be derived based on the resistance value R, capacitance C, and CPE index p, which are parameters of each element in the equivalent circuit. Furthermore, the conductivity of slurry Xc can be derived based on the resistance value R, capacitance C, CPE constant T, and CPE index p, which are parameters of each element in the equivalent circuit. Therefore, data that can objectively determine the state of the mixture can be obtained.

[0191] As shown in this embodiment, the state measuring device 1 is preferably used for a slurry for the positive electrode of a lithium-ion battery, which is formed by dispersing active material, binder and conductive additive as solid substances in a solvent.

[0192] [Other implementation methods for equivalent circuit analysis and index derivation calculation]

[0193] <First Variation>

[0194] Figure 8 It is used to represent Figure 5 The diagram illustrates a first variation of the equivalent circuit of the model shown.

[0195] like Figure 8 As shown, Figure 6 The equivalent circuit shown can also be replaced by an equivalent circuit that takes the parallel circuit consisting of resistor R and capacitor C as one element.

[0196] In the case of the first variation, the number of parallel circuits (elements) can also be set based on the amount of resistive components of the solid material contained in the slurry Xc, just as in the equivalent circuit analysis described above.

[0197] Furthermore, in the first modified example, the complex plane impedance of the slurry Xc can be defined by the following equation (3).

[0198] [Formula 8]

[0199]

[0200] In the equivalent circuit analysis of the first variation, the equivalent circuit analysis module 114 performs fitting processing on the impedance complex plane diagram A and the impedance complex plane diagram B, and calculates Rk and Ck. Furthermore, the derivation module 115 derives the relaxation time τ based on the product of Rk and Ck using the following formula. k .

[0201] [Formula 9]

[0202] τ k calc =R k C k

[0203] The derivation module 115 shows the relationship between setting the horizontal axis to the relaxation time τ and the vertical axis to the resistance value R.

[0204] Figure 9 This is a graph showing the relationship between the relaxation time τ and the resistance value R, generated by the derivation module 115. The derivation module 115... Figure 9 The τ-R diagram shown defines a region S divided by any interval τ1 to τ2. 12 .

[0205] According to the first variation, as shown in equation (4) below, by calculating the region S 12 The variance of the relaxation time τ in the slurry can be used to derive the uniformity u of the slurry Xc. Furthermore, as shown in equation (5) below, the uniformity u can also be determined based on the region S. 12 The half-amplitude value of R in the equation is derived.

[0206] Furthermore, the conductivity α of the slurry Xc can be derived from the following formula (6) or formula (7).

[0207] [Formula 10]

[0208]

[0209] Average value, N 12 Number of points

[0210] u = [S 12 [Half-amplitude value in the middle]...(5)

[0211]

[0212] α=S 12 The average value of R in…(7)

[0213] Furthermore, the relaxation time τ of each element was calculated by equivalent circuit analysis of the measured impedance of the slurry Xc. kthe standard relaxation time τ of each element obtained by measuring a reference slurry whose state is known λ ref By comparing, the impedance value of each element and the kind of solid substance (the kind of interface between solid substances) can be determined.

[0214] <Second Modification>

[0215] Figure 10 is a graph for explaining a second modification of the equivalent circuit of the model shown in Figure 5

[0216] In the second modification, the internal resistance component of the solid substance can be represented by using a discrete representation (R ix , C ix ), (R iy , C iy ), (R iz , C iz ), and the contact resistance component of the solid substances to each other can be represented by R i-j , C i-j . Note that each resistance component can also be represented by using a continuous representation instead of the discrete representation.

[0217] In the equivalent circuit analysis of the second modification, the equivalent circuit analysis module 114 performs the fitting process of the impedance complex plane graph A and the impedance complex plane graph B using the equivalent circuit based on the three-dimensional mesh model shown in Figure 10 , and calculates each parameter of the equivalent circuit.

[0218] The derivation module 115 illustrates the correspondence relation in which the horizontal axis is the resistance value R and the vertical axis is the occurrence frequency of R.

[0219] Figure 11 is a graph representing the correspondence relation of the resistance value R and the occurrence frequency made by the derivation module 115. The derivation module 115 sets the region S 12 divided by an arbitrary interval R1 to R2 in the graph illustrated in Figure 11 .

[0220] According to the second modification, by calculating the variance of the resistance value R in the region S 12 , the uniformity u of the slurry Xc can be derived as shown in the following expression (8). Further, the uniformity u can also be derived from the half value of the occurrence frequency in the region S 12 as shown in the following expression (9).

[0221] Further, the conductivity a of the slurry Xc can be derived according to the following expression (10) or expression (11). ​

[0222] [Formula 11]

[0223]

[0224] Average, N 12 : Number of points

[0225] u = [S 12 in the frequency half value]... (9)

[0226]

[0227] a = S 12 in the average value of R... (11)

[0228] Further, in the equivalent circuit of the three-dimensional mesh model shown in Figure 10 , the relaxation time is represented by the following formula.

[0229] [Formula 12]

[0230]

[0231] The relaxation time τ of each element calculated by the equivalent circuit analysis of the measured impedance of the slurry Xc ix(iy，iz) calc The standard relaxation time τ of each element obtained with respect to a reference slurry whose state is known λ ref Comparing these, the impedance value of each element and the kind of solid matter (the kind of interface between solid matters) can be determined.

[0232] <Third Modification>

[0233] As the third modification, the relaxation time τ and the resistance value R among the parameters of the equivalent circuit calculated using the three-dimensional mesh model of the second modification can also be illustrated by the correspondence relationship in which the horizontal axis is set to the relaxation time τ and the vertical axis is set to the resistance value R, as in the first modification.

[0234] The derivation module 115 obtains the τ-R graph in the same manner as shown in Figure 9 , sets the region S 12 divided by an arbitrary interval τ1-τ2, and applies the formulas (4) to (7), whereby the uniformity u of the slurry Xc can be derived.

[0235] <Fourth Modification>

[0236] As the third modification, the derivation module 115 uses the parameters of the equivalent circuit calculated using the three-dimensional mesh model of the second modification to perform the following processing.

[0237] The model used in the fourth modification can be approximated less and can be set to a model close to the actual state of the slurry Xc.

[0238] In the equivalent circuit analysis of the second modification, the equivalent circuit analysis module 114 performs the fitting process of the impedance complex plane A and the impedance complex plane B using the equivalent circuit based on the three-dimensional mesh model, and calculates the resistance value R corresponding to each element of the three-dimensional mesh in correspondence with the position coordinates of each element. i .

[0239] In the three-dimensional mesh, the resistance value R i is set to an arbitrary range R1 to R2. In the region Ω 12 set by the range, the resistance value R i obtained by the fitting process is extracted. x The position coordinates (i y , i z ) at which the resistance value R i becomes a value converging on R1 to R2 are mesh in which the occurrence frequency of the resistance value R x is 1.

[0240] Figure 12A is a graph showing the correspondence relationship of the position coordinates i and the occurrence frequency of R made by the derivation module 115. Herein, Figure 12A is represented by a discrete representation method. Figure 12B is a graph showing the correspondence relationship of the position coordinates i and the occurrence frequency of R made by the derivation module 115 by a continuous representation method.

[0241] As shown in Figure 12B , the derivation module 115 illustrates the correspondence relationship of the occurrence frequency of R with the horizontal axis set as i x and the vertical axis set as R. The horizontal axis can also be i y , i z In the i-R graph, a region S 12 divided by an arbitrary interval i1 to i2 is set.

[0242] The derivation module 115 can derive the uniformity u and the conductivity a of the slurry Xc by Equations (12) to (15).

[0243] [Equation 13]

[0244]

[0245] Average, N 12 : number of points

[0246] u = [frequency half value in S 12 ]... (13)

[0247]

[0248] α = S 12 Average value of R in (15)

[0249] Note that, in Figure 12A In this case, the uniformity u can be calculated by the following equation.

[0250] [Equation 14]

[0251]

[0252] [Other Embodiments]

[0253] The above describes embodiments of the present application, but the above embodiments merely show a part of application examples of the present application, and are not intended to limit the technical scope of the present application to the specific configurations of the above embodiments.

[0254] The state measuring device 1 has a pair of electrodes 2, but can have three or more electrodes. With three or more electrodes, the impedance of the slurry Xc can be measured.

[0255] In the state measuring device 1, the storage section 32, the operation section 33, and the display section 34 can be provided separately from the measuring device main body 3. Further, the measuring section 31 can be provided separately from the state measuring device 1, for example, as another device like an analysis device.

[0256] The state measuring device 1 can take various forms. For example, the state measuring device 1 can be configured as a stationary device. Further, the state measuring device 1 can be configured as a portable device.

[0257] [Example]

[0258] Using the state measuring device 1 of the present embodiment, the physical and electrical properties of the mixed solution were derived, and the mixed solution was evaluated. As the mixed solution, a slurry for a positive electrode of a lithium ion battery was used.

[0259] <Composition of the sample>

[0260] The composition of the sample is described below.

[0261] (Solid substance)

[0262] Active material: LiC02 42.3 mass%

[0263] Conductive aid: furnace carbon black 2.4 mass%

[0264] Binder resin: polyvinylidene fluoride resin (PVdF) 2.4 mass%

[0265] (solvent)

[0266] N-methylpyrrolidone (NMP) 52.9 mass %

[0267] That is, the sample is a slurry in which LiCO2, furnace carbon black, and PVdF are dispersed in N-methylpyrrolidone (NMP) as a solvent.

[0268] <Production of sample>

[0269] For the above slurry, a plurality of samples were produced in which the stirring time was different. Specifically, samples in which the stirring time was 1 minute, 6 minutes, 12 minutes, 18 minutes, 24 minutes, and 30 minutes were produced. The stirring of the slurry was performed by an awatoritairo manufactured by THINKY Co., Ltd.

[0270] <Measurement of state of sample>

[0271] The state of each sample produced in which the stirring time was different was measured using the state measurement device 1. In this example, as indices for determining the state of the slurry, an index related to uniformity among physical properties and an index related to electrical conductivity among electrical properties were derived, respectively.

[0272] The results are shown in Figure 13 and Figure 14 .

[0273] <Results>

[0274] Figure 13 is a graph showing the index of electrical conductivity with respect to the stirring time, Figure 14 is a graph showing the index of uniformity with respect to the stirring time.

[0275] According to Figure 13 it is known that the electrical conductivity of the slurry becomes good by setting the stirring time to be long, but if the stirring time exceeds 12 minutes, the electrical conductivity decreases, and there is a tendency to converge to a certain value.

[0276] Further, according to Figure 14 it is known that the uniformity of the slurry becomes good by setting the stirring time to be long, and reaches a peak between 12 minutes and 24 minutes of the stirring time, and thereafter, there is a tendency to stabilize around the peak.

[0277] Figures 15 to 18 is a schematic diagram for explaining the state of the slurry, and is a schematic diagram showing the state in which the conductive aid is dispersed in the organic solvent containing the binder resin. Figure 15 is a schematic diagram for explaining the state of the slurry in which both the uniformity and the electrical conductivity are good, Figure 16is a schematic diagram for explaining the state of a slurry in which uniformity is poor but electric conductivity is good. Furthermore, Figure 17 is a schematic diagram for explaining the state of a slurry in which uniformity is good but electric conductivity is poor, Figure 18 is a schematic diagram for explaining the state of a slurry in which both uniformity and electric conductivity are poor.

[0278] In the state shown in Figure 15 , the active material is moderately dispersed as single particles in the organic solvent. Furthermore, the dispersed active material is connected to each other by the binding of single particles of the electrically conductive aid, thereby forming an electrically conductive path.

[0279] Figure 16 The state shown in is a state in which a part of the active material forms secondary particles, and an electrically conductive path is formed by the binding of single particles, secondary particles, or both of them of the electrically conductive aid between single particles of the active material or between secondary particles of the active material. It is considered that the slurry at the initial stage of the stirring time becomes such a state.

[0280] In the state shown in Figure 17 , the active material is dispersed as single particles, but the electrically conductive aid is also dispersed, and a sufficient conductive path connecting the active materials to each other is not formed. It is considered that the slurry at the latter half of the stirring time becomes this state. In the case of such a slurry, even if the uniformity is good, an electrically conductive path is not easily formed, and thus it is considered that the electric characteristics are exhibited to be low.

[0281] In the state shown in Figure 18 , a part of the active material forms secondary particles, and a part of the electrically conductive aid also forms secondary particles. It is considered that the slurry becomes this state after the stirring has just started.

[0282] If the stirring time is appropriate, it is considered that the slurry becomes the state shown in Figure 15 . Such a slurry is good in both uniformity and electric conductivity.

[0283] As described above, according to the measurement using the state measurement device 1, the physical characteristics and the electric characteristics of the slurry can be acquired, and thus for the uniformity and the electric conductivity of the slurry, a condition in which the balance between the two can be adjusted according to the purpose can be managed.

[0284] Furthermore, according to the state measurement device 1 of the present embodiment, an index for determining the electric characteristics and an index for determining the physical characteristics can be easily derived, and thus it is advantageous in the field of managing the quality of a mixed liquid like a slurry.

[0285] This application claims priority based on Japanese Patent Application No. 2020-133419 filed on August 5, 2020 with the Japan Patent Office, the entire contents of which are incorporated herein by reference.

Claims

1. A state measuring device for measuring the state of a mixture containing an insoluble solid substance in a liquid, wherein, The state measuring device includes: Electrodes apply an AC signal to the mixture; The measuring unit measures the impedance of the mixture at each frequency of the AC signal, based on the response signal of the flow in the mixture when the AC signal is applied. The setting unit sets an equivalent circuit including one or more parallel circuits based on elements corresponding to the electrical composition of the solid material; The calculation unit performs equivalent circuit analysis to approximate the impedance of the equivalent circuit to the impedance of the mixture to calculate the parameters of the parallel circuit. as well as The derivation unit derives indices for determining the state of the mixture based on the parameters of the parallel circuit. The setting unit sets an equivalent circuit that includes at least a series circuit formed by connecting a parallel circuit corresponding to the internal resistance component of the solid material and a parallel circuit corresponding to the contact resistance component between the solid materials. When multiple solid substances are mixed in the mixture, the setting unit sets parallel circuits corresponding to the internal resistance components of each of the multiple solid substances, parallel circuits corresponding to the contact resistance components between the same solid substances, and parallel circuits corresponding to the contact resistance components between different solid substances.

2. The state measuring device according to claim 1, wherein, The parallel circuit is at least one of a parallel circuit of a resistor and a capacitor, and a parallel circuit of a resistor and a constant phase element.

3. The state measuring device according to claim 1 or 2, wherein, The derivation unit derives the homogeneity of the mixture based on at least one of the resistance values ​​of one or more of the parallel circuits, the capacitance of the capacitor, and the CPE index p.

4. The state measuring device according to claim 1 or 2, wherein, The derivation unit derives the conductivity of the mixture based on at least one of the following: the resistance value of one or more of the parallel circuits, the capacitance of the capacitor, the CPE constant T, and the CPE exponent p.

5. The state measuring device according to claim 1, wherein, The electrical component includes at least one of the internal resistance component of the solid material and the contact resistance component between the solid materials.

6. The state measuring device according to claim 5, wherein, The mixture contains a number of solid substances. The equivalent circuit includes a series circuit, which connects in series the parallel circuit corresponding to the internal resistance component of the first solid material, the parallel circuit corresponding to the contact resistance component of the first solid material, the parallel circuit corresponding to the internal resistance component of the second solid material, the parallel circuit corresponding to the contact resistance component of the second solid material, and the parallel circuit corresponding to the contact resistance components of the first solid material and the second solid material.

7. The state measuring device according to claim 5 or 6, wherein, The setting unit sets the number of parallel circuits to be less than the total number of the internal resistance component and the contact resistance component of the solid substance in the mixture.

8. The state measuring device according to claim 5 or 6, wherein, The mixture contains a number of solid substances. The derivation unit derives an index for determining the state of the mixture based on the value obtained by combining at least one parameter of a resistor, capacitor, and constant phase element in a parallel circuit corresponding to the internal resistance component of the plurality of solid substances or a parallel circuit corresponding to the contact resistance component.

9. The state measuring device according to any one of claims 1, 5, and 6, wherein, The mixture is a slurry used as the positive or negative electrode of a lithium-ion battery, and contains active materials, binders, and conductive additives as the solid material.

10. A method for determining the state of a mixture containing an insoluble solid substance in a liquid, wherein, The AC signal is applied to the mixture while its frequency is varied. Based on the response signal of the flow in the mixture when the AC signal is applied, the impedance of the mixture is measured at each frequency of the AC signal. Based on the measured impedance, an equivalent circuit is derived, comprising parallel circuits based on elements corresponding to the electrical components of the solid material. This equivalent circuit includes at least a series circuit formed by connecting parallel circuits corresponding to the internal resistance components of the solid material and parallel circuits corresponding to the contact resistance components between the solid materials. When multiple solid substances are mixed in the mixture, parallel circuits are set up corresponding to the internal resistance components of each of the multiple solid substances, parallel circuits corresponding to the contact resistance components between the same solid substances, and parallel circuits corresponding to the contact resistance components between different solid substances. The parameters of the parallel circuit are calculated by performing an equivalent circuit analysis to approximate the impedance of the equivalent circuit to that of the mixture. Based on the parameters of the parallel circuit, an index for determining the state of the mixture is derived.

11. A recording medium having a program for causing a computer to perform a determination of the state of a mixture containing insoluble solid substances in a liquid, wherein, The recording medium records a program for performing the following state determination method: The AC signal is applied to the mixture while its frequency is varied. Based on the response signal of the flow in the mixture when the AC signal is applied, the impedance of the mixture is measured at each frequency of the AC signal. Based on the measured impedance, an equivalent circuit is derived, comprising parallel circuits based on elements corresponding to the electrical components of the solid material. This equivalent circuit includes at least a series circuit formed by connecting parallel circuits corresponding to the internal resistance components of the solid material and parallel circuits corresponding to the contact resistance components between the solid materials. When multiple solid substances are mixed in the mixture, parallel circuits are set up corresponding to the internal resistance components of each of the multiple solid substances, parallel circuits corresponding to the contact resistance components between the same solid substances, and parallel circuits corresponding to the contact resistance components between different solid substances. The parameters of the parallel circuit are calculated by performing an equivalent circuit analysis to approximate the impedance of the equivalent circuit to that of the mixture. Based on the parameters of the parallel circuit, an index for determining the state of the mixture is derived.

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