System and method

Abstract

To provide a system that determines the state of an all-solid-state battery.SOLUTION: A system includes a detection apparatus and a determination apparatus. An all-solid-state battery includes a positive electrode layer, a solid electrolyte layer, and a negative electrode layer in this order. The negative electrode layer includes a negative-electrode active material. The detection apparatus is configured to detect a state quantity. The state quantity includes at least one of an external dimension of the all-solid-state battery and confining pressure applied to the all-solid-state battery. The determination apparatus is configured to determine that an abnormality has occurred in the all-solid-state battery when the fluctuation of the state quantity turns to an increasing trend from a decreasing trend.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to systems and methods. [Background technology]

[0002] Japanese Patent Application Laid-Open No. 2019-179731 discloses an all-solid-state battery negative electrode containing silicon. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-179731 Summary of the Invention [Problem to be solved by the invention]

[0004] Liquid-type batteries contain an electrolyte (liquid). Methods have been proposed for determining the state of liquid-type batteries by monitoring various state quantities. All-solid-state batteries are made of solids only. All-solid-state batteries have a different degradation pattern than liquid-type batteries. It is possible that the state of an all-solid-state battery cannot be properly determined using the same methods as liquid-type batteries.

[0005] An object of the present disclosure is to provide a system for determining the state of an all-solid-state battery. [Means for solving the problem]

[0006] The technical configuration and effects of the present disclosure will be described below. However, the mechanism of action of the present disclosure includes speculation. The mechanism of action does not limit the technical scope of the present disclosure.

[0007] 1. One aspect of the present disclosure is a "system" for determining the state of an all-solid-state battery. The system includes a detection device and a determination device. The all-solid-state battery includes a positive electrode layer, a solid electrolyte layer, and a negative electrode layer, in this order. The negative electrode layer includes a negative electrode active material. The detection device is configured to detect a state quantity. The state quantity includes at least one of the external dimensions of the all-solid-state battery and a confining pressure applied to the all-solid-state battery. The determination device is configured to determine that an abnormality has occurred in the all-solid-state battery when the transition of the state quantity changes from a decreasing trend to an increasing trend.

[0008] The state quantity in this disclosure includes at least one of the outer dimension (e.g., thickness) and the confining pressure. When a battery is constrained by a constraining member, it is believed that there is a positive correlation between the outer dimension and the constraining pressure. It is believed that the change in the outer dimension and the change in the constraining pressure show the same trend.

[0009] In general, the transition of the state quantities of a liquid battery continues to increase. That is, as the number of cycles increases, a liquid battery may continuously expand. In a liquid battery, the negative electrode layer is porous. An electrolyte permeates the pores of the negative electrode layer. The negative electrode active material may expand during charging and contract during discharging. Even if the electrolyte is consumed, it may again permeate the pores due to the reaction of the electrolyte with the negative electrode active material. Therefore, it is thought that rearrangement of the negative electrode active material (particles), gas generation, and formation of an SEI (Solid Electrolyte Interphase) film may continuously occur within the negative electrode layer of a liquid battery. As a result, a liquid battery may continuously expand.

[0010] On the other hand, according to the new findings of the present disclosure, the transition of state quantities in an all-solid-state battery can shift from a decreasing trend to an increasing trend. All-solid-state batteries are composed only of solids. The negative electrode layer is dense. The solid electrolyte has no fluidity. Therefore, it is believed that rearrangement of the negative electrode active material, gas generation, and SEI film formation are unlikely to occur continuously within the negative electrode layer of an all-solid-state battery. The negative electrode active material may expand significantly during the initial charge. The amount of expansion of the negative electrode active material during charging can gradually decrease with repeated charge and discharge. Therefore, it is believed that the transition of the thickness of an all-solid-state battery will show a decreasing trend.

[0011] However, for example, if peeling occurs at the interface between the anode layer and the solid electrolyte layer, the conduction paths (ionic conduction paths and electronic conduction paths) are locally and rapidly reduced. That is, the anode reaction is unevenly distributed in the in-plane direction of the anode layer. The anode active material that has lost its conduction paths can no longer contribute to the anode reaction. As a result, current is concentrated in the anode active material that still has conduction paths. The anode active material where the current is concentrated may be charged more than expected. It is thought that the anode active material expands more than expected, causing the thickness of the all-solid-state battery to begin to increase. Subsequently, the expansion of the uneven anode reaction may rapidly progress the capacity degradation of the all-solid-state battery.

[0012] That is, the turning point at which the transition of the state quantity changes from a decreasing trend to an increasing trend can be considered to be the turning point at which the state of the all-solid-state battery changes from “normal” to “abnormal.” By determining that an abnormality has occurred in the all-solid-state battery based on the increasing trend of the transition, appropriate measures can be taken before a rapid deterioration of capacity occurs.

[0013] 2. The system described in the above item "1" may include, for example, the following configuration: The negative electrode active material includes silicon (Si).

[0014] Negative electrode active materials containing Si tend to expand significantly when overcharged. When the negative electrode active material contains Si, the negative electrode reaction may become uneven, which may accelerate capacity degradation. Therefore, when the negative electrode active material contains Si, the above system "1" is considered to be particularly effective.

[0015] 3. The system described in paragraph "1" or "2" above may include, for example, the following configuration: The determination device is configured to determine that the transition of the state quantity is on an increasing trend when the relationship "1.05≦(A1 / A0)" is satisfied. A0 indicates the initial value of the state quantity. A1 indicates the current value of the state quantity.

[0016] After the state quantity transitions from a decreasing trend to an increasing trend, the state quantity continues to increase, causing the current value (A1) of the state quantity to become greater than the initial value (A0). For example, when the ratio (A1 / A0) of the current value to the initial value becomes 105% or more, it may be determined that the transition is on an increasing trend.

[0017] 4. The system described in any one of the above paragraphs "1" to "3" may include, for example, the following configuration: the detection device is configured to detect a state quantity when the all-solid-state battery is being charged, and the determination device is configured to monitor a transition of the state quantity as the number of times the battery is charged increases.

[0018] During charging, the negative electrode active material expands. Measuring the state quantity during charging is expected to improve the accuracy of the determination. The horizontal axis of the transition can be any axis as long as it represents the usage history of the battery. For example, the transition as the number of charges increases may be monitored. Counting the number of charges can be simple.

[0019] 5. One aspect of the present disclosure is a "method" for determining the state of an all-solid-state battery. The method includes the following (a) and (b): (a) Detect the state quantity. (b) When the transition of the state quantity changes from a decreasing trend to an increasing trend, it is determined that an abnormality has occurred in the all-solid-state battery. The all-solid-state battery includes a positive electrode layer, a solid electrolyte layer, and a negative electrode layer, in that order. The negative electrode layer includes a negative electrode active material. The negative electrode active material includes silicon. The state quantity includes at least one of the external dimensions of the all-solid-state battery and the confining pressure applied to the all-solid-state battery. The state quantity is detected when the all-solid-state battery is charged. The transition of the state quantity as the number of charges increases is monitored. When the relationship "1.05≦(A1 / A0)" is satisfied, it is determined that the transition of the state quantity is on an increasing trend. A0 indicates the initial value of the state quantity. A1 indicates the current value of the state quantity.

[0020] Hereinafter, one embodiment of the present disclosure (hereinafter may be abbreviated as "this embodiment") and one example of the present disclosure (hereinafter may be abbreviated as "this example") will be described. However, this embodiment and this example do not limit the technical scope of the present disclosure. This embodiment and this example are illustrative in all respects. This embodiment and this example are non-restrictive. The technical scope of the present disclosure encompasses all modifications within the meaning and scope equivalent to the claims. For example, it is originally intended that any configurations may be extracted from this embodiment and arbitrarily combined. [Brief explanation of the drawings]

[0021] [Figure 1] FIG. 1 is a block diagram illustrating an example of a system according to an embodiment of the present invention. [Figure 2] 1 is a schematic flowchart illustrating an example of a method according to the present embodiment. [Figure 3] 10 is a graph showing an example of a transition of a state quantity. [Figure 4] FIG. 1 is a conceptual diagram illustrating an experimental method. DETAILED DESCRIPTION OF THE INVENTION

[0022] -Terms and phrases- "Comprises," "includes," "has," and variations thereof are open-ended expressions. An open-ended structure may or may not further include additional elements in addition to the required elements. "Consists of" is a closed expression. However, even a closed structure may include additional elements that are normally associated impurities or unrelated to the subject technology. "Consists essentially of..." is a semi-closed expression. A semi-closed structure allows the addition of elements that do not substantially affect the basic and novel characteristics of the subject technology.

[0023] Expressions such as "may" and "may" are used in the permissive sense, meaning "to have the possibility," rather than in the obligatory sense, meaning "to have to."

[0024] Unless otherwise specified, the order of execution of multiple steps, actions, operations, etc. included in various methods is not limited to the order described. For example, multiple steps may proceed simultaneously. For example, multiple steps may occur one after the other.

[0025] For example, the phrase "at least one of A and B" includes "A or B" as well as "A and B." "At least one of A and B" can also be written as "A and / or B."

[0026] "SOC (State Of Charge)" indicates the percentage of a battery's fully charged state minus the percentage of discharged electricity. The SOC of a fully charged state is 100%. The SOC of a fully discharged state is 0%.

[0027] "Confinement pressure" is calculated by dividing the force (load) applied to the battery by the area of ​​the surface receiving the force. The confinement pressure may be calculated, for example, from the relational expression "σ = E / ε." "σ" represents the confinement pressure. "ε" represents the amount of change (reduction) in the thickness of the battery before and after the confinement member is attached. "E" represents the Young's modulus of the battery.

[0028] -system- FIG. 1 is a block diagram showing an example of a system according to the present embodiment. Hereinafter, the "system according to the present embodiment" may be abbreviated as "the present system." The present system 10 determines the state of an all-solid-state battery 20. The present system 10 includes a detection device 11 and a determination device 12. Each device may be integrally formed or may be independent. The all-solid-state battery 20 may be included in the present system 10 or may be independent from the present system 10. A restraining pressure may be applied to the all-solid-state battery 20 by a restraining member 30. The restraining member 30 may be included in the present system 10 or may be independent from the present system 10.

[0029] The system 10 may be used in any application. For example, the system 10 may be mounted on a vehicle. That is, the system 10 may operate on-board. The vehicle may be, for example, a battery electric vehicle (BEV), a hybrid electric vehicle (HEV), or a plug-in hybrid electric vehicle (PHEV).

[0030] The system 10 may operate off-board. For example, the system 10 may operate in the home of a vehicle user, a charging device owned by the vehicle user, a charging stand (also referred to as a charging station or a charging spot), or the like.

[0031] 2 is a schematic flowchart showing an example of the method according to the present embodiment. Hereinafter, the "method according to the present embodiment" may be abbreviated as "the present method." The present system 10 may implement the present method.

[0032] -Detection device- The detection device 11 detects a state quantity. That is, the present method includes detecting the state quantity. The state quantity includes at least one of an outer dimension of the all-solid-state battery 20 and a confining pressure applied to the all-solid-state battery 20. The outer dimension may include, for example, at least one selected from the group consisting of a thickness, a width, and a length.

[0033] The detection device 11 may include various sensors. The sensors measure state quantities. For example, if the detection target is "thickness," the detection device 11 may include various displacement sensors. The displacement sensors may measure dimensions using any method. The displacement sensors may be attached to, for example, a restraining member 30 (described later). The displacement sensors may be, for example, a position sensitive device (PSD) type, a charge coupled device (CCD) type, a laser type, an ultrasonic type, a differential transformer type, a magnetic detection type, or the like.

[0034] For example, when the detection target is "confining pressure," the detection device 11 may include various pressure sensors. The pressure sensor may include, for example, a load cell, a pressure measurement film (tactile sensor), etc. For example, a load cell may be installed in contact with the constraint member 30. For example, a pressure measurement film may be sandwiched between the constraint member 30 and the all-solid-state battery 20. The pressure measurement film may measure the pressure over the entire surface of the contact surface between the constraint member 30 and the all-solid-state battery 20. The arithmetic average value of the pressure measured at each part of the pressure measurement film may be calculated. The pressure measurement film may also measure the pressure locally. For example, the pressure at the center of the contact surface may be measured.

[0035] The detection device 11 can detect the state quantity at any timing. The detection device 11 may detect the state quantity at a specific timing. The state quantity may be detected, for example, during charging. For example, the state quantity may be detected during charging at night at the vehicle user's home. For example, the state quantity may be detected during charging at a charging station.

[0036] Detecting the state quantity at a high SOC is expected to improve the accuracy of the determination. The SOC at which the state quantity is detected may be, for example, 50% or more, 60% or more, 70% or more, 80% or more, 90% or more, or 95% or more. The SOC at which the state quantity is detected may be, for example, 100% or less, 95% or less, or 90% or less.

[0037] The detection device 11 may include, for example, an input device (not shown). The detection value of the sensor may be input to the input device. The input device may be connected to, for example, a storage device (described later). The detection value may be stored in the storage device.

[0038] -Judgment device- The determination device 12 determines that an abnormality has occurred in the all-solid-state battery 20 when the transition of the state quantity changes from a decreasing trend to an increasing trend. That is, this method includes determining that an abnormality has occurred in the all-solid-state battery 20 when the transition of the state quantity changes from a decreasing trend to an increasing trend.

[0039] The determination device 12 may include, for example, a storage device and a calculation device. The determination device 12 acquires, for example, the state quantity detected by the detection device 11. The storage device may accumulate the state quantity at each detection time point. For example, based on the history data of the state quantity, the calculation device may create a transition graph (two-dimensional graph) with each detection time point as the horizontal axis and the state quantity as the vertical axis.

[0040] FIG. 3 is a graph showing an example of the transition of a state quantity. In FIG. 3, thickness is measured as an example of the state quantity. For reference, FIG. 3 also shows the transition of battery capacity. The horizontal axis of the graph is a value representing the usage history of the all-solid-state battery 20. The horizontal axis may be, for example, the number of state quantity detections, the number of cycles, elapsed time, the number of elapsed days, the number of charges, the number of discharges, etc. The number of charges may be the same value as the number of cycles. The number of charges may be, for example, the number of times a predetermined SOC is reached. The predetermined SOC may be, for example, 50% or more, 60% or more, 70% or more, 80% or more, 90% or more, or 95% or more. The predetermined SOC may be, for example, 100% or less, 95% or less, or 90% or less.

[0041] In Figure 3, for example, the number of cycles is plotted on the horizontal axis. At the beginning of use, the thickness gradually decreases as the number of cycles increases. In other words, the transition is a decreasing trend. As the number of cycles increases, the thickness reaches a turning point (tp). After the turning point (tp), the thickness begins to increase. In other words, at the turning point (tp), the transition changes from a decreasing trend to an increasing trend.

[0042] After the turning point (tp), the battery capacity begins to decrease rapidly. It is believed that the unevenness of the anode reaction is small from the beginning of use until the turning point (tp). It is believed that the unevenness of the anode reaction increases after the turning point (tp). For example, partial peeling may have occurred at the interface between the anode layer 22 and the solid electrolyte layer 23.

[0043] The determination device 12 may monitor the transition of the state quantity. For example, the determination device 12 may monitor the transition of the state quantity as the number of charging times increases. For example, the determination device 12 may determine whether the transition is on a decreasing trend or an increasing trend based on five consecutive detection results of the state quantity. For example, the determination device 12 may determine that the transition is on a decreasing trend if three or more of the five consecutive detection results of the state quantity are decreased from the previous detection value. For example, the determination device 12 may determine that the transition is on an increasing trend if three or more of the five consecutive detection results of the state quantity are increased from the previous detection value.

[0044] For example, the calculation device may differentiate the transition curve to detect a minimum value of the transition curve. For example, the minimum value of the transition curve may be regarded as a turning point (tp). Upon detecting the turning point (tp), it may be determined that the transition has entered an increasing trend.

[0045] For example, when the relationship "1.05≦(A1 / A0)" is satisfied, it may be determined that the transition is on an increasing trend. "A0" indicates the initial value of the state quantity (e.g., initial thickness, initial confining pressure). "A1" indicates the current value of the state quantity.

[0046] For example, when the relationship "1.04≦(A1 / A0)", "1.03≦(A1 / A0)", or "1.02≦(A1 / A0)" is satisfied, it may be determined that the trend is increasing. For example, "1.05=(A1 / A0)" may be synonymous with 105% in FIG. 3.

[0047] When the transition is on an increasing trend, the determination device 12 determines that an abnormality has occurred in the all-solid-state battery 20. The determination device 12 may output the determination result (occurrence of an abnormality). The determination device 12 may notify the user of the occurrence of the abnormality. For example, the determination device 12 may prompt the user to replace the all-solid-state battery 20.

[0048] -Other devices- The system 10 may further include, for example, a display device (not shown). For example, the display device may notify the user of the determination result (occurrence of an abnormality). The display device may include, for example, a display, a speaker, etc. For example, the determination device 12 may include the display device.

[0049] The system 10 may further include, for example, a control device (not shown). The control device may control each device included in the system 10. For example, the control device may change the usage conditions of the all-solid-state battery 20 based on the determination result of the determination device 12. After the occurrence of an abnormality, the control device may change at least one selected from the group consisting of an upper limit charge current, an upper limit discharge current, an upper limit SOC, a lower limit SOC, and a confining pressure. For example, the upper limit charge current (maximum current) may be reset to a value lower than its initial value. For example, the upper limit SOC may be reset to a value lower than its initial value. Changing the usage conditions may, for example, reduce rapid capacity degradation.

[0050] -All-solid-state battery- The all-solid-state battery 20 may have any external shape. The all-solid-state battery 20 may have, for example, a plate-like external shape. The all-solid-state battery 20 may include, for example, a power generating element 25 and an exterior body 28. The exterior body 28 may house the power generating element 25. The exterior body 28 may have any form. The exterior body 28 may be, for example, a metal case or the like. The exterior body 28 may be, for example, a pouch made of an Al laminate film or the like.

[0051] The power generating element 25 includes a positive electrode layer 21, a solid electrolyte layer 23, and a negative electrode layer 22, in this order. The power generating element 25 may have any structure. For example, the power generating element 25 may have a monopolar structure or a bipolar structure. For example, the power generating element 25 may be formed by alternately stacking the positive electrode layers 21 and the negative electrode layers 22 with the solid electrolyte layer 23 sandwiched therebetween.

[0052] The positive electrode layer 21 may include, for example, a positive electrode active material layer and a positive electrode current collector. The positive electrode active material layer may be disposed on one side of the positive electrode current collector, or on both sides of the positive electrode current collector. The positive electrode current collector may include, for example, aluminum (Al) foil, Al alloy foil, or the like.

[0053] The positive electrode active material layer includes a positive electrode active material. The positive electrode active material may be a powder. The positive electrode active material can reversibly store lithium (Li). The positive electrode active material may include any component. The positive electrode active material may include, for example, lithium nickel cobalt manganese composite oxide (NCM), lithium nickel cobalt aluminum composite oxide (NCA), lithium iron phosphate (LFP), or the like. The positive electrode active material may be coated with an oxide film. The oxide film may include, for example, niobium (Nb), titanium (Ti), phosphorus (P), boron (B), or the like.

[0054] The positive electrode layer 21 includes a solid electrolyte. The solid electrolyte may be a powder. The solid electrolyte can form an ion conduction path. The solid electrolyte may include, for example, a sulfide solid electrolyte. The sulfide solid electrolyte may include at least one selected from the group consisting of an amorphous phase, a crystalline phase, and a glass ceramic (crystallized glass) phase. The crystalline phase may be, for example, an argyrodite type or an LGPS type. The sulfide solid electrolyte includes Li and sulfur (S). The sulfide solid electrolyte may further include any component in addition to Li and S. The sulfide solid electrolyte may have, for example, a composition represented by the following general formula: yLiI-zLiBr-(100-yz)[xLi2S-(1-x)P2S5] In the formula, x may be, for example, 0.5 to 0.9. y may be, for example, 0 to 30. z may be, for example, 0 to 30. In the formula, when x = 0.75, y = 10, and z = 0, the composition is "10LiI-90[0.75Li2S-0.25P2S5]". This composition indicates that the mixing ratio (mass ratio) of each raw material is "LiI:LiBr:(0.75Li2S-0.25P2S5) = 10:0:90". "0.75Li2S-0.25P2S5" indicates that the mixing ratio of each raw material is "Li2S:P2S5 = 0.75:0.25". "0.75Li2S-0.25P2S5" may be expressed as, for example, "Li3PS4". The sulfide solid electrolyte can be synthesized, for example, by a mechanochemical method.

[0055] The positive electrode layer 21 may further include a conductive material. The conductive material can form an electron conduction path. The conductive material may include, for example, at least one selected from the group consisting of acetylene black (AB), vapor-grown carbon fiber (VGCF), carbon nanotubes (CNT), and graphene flakes (GF). The positive electrode layer 21 may further include a binder. The binder can bind solid components. The binder may include, for example, polyvinylidene fluoride (PVdF), vinylidene fluoride-hexafluoropropylene copolymer (PVdF-HFP), styrene butadiene rubber (SBR), etc.

[0056] The negative electrode layer 22 may include, for example, a negative electrode active material layer and a negative electrode current collector. The negative electrode active material layer may be disposed on one side of the negative electrode current collector, or on both sides of the negative electrode current collector. The negative electrode current collector may include, for example, copper (Cu) foil, Cu alloy foil, nickel (Ni) foil, Ni alloy foil, etc.

[0057] The negative electrode active material layer contains a negative electrode active material. The negative electrode active material may be in powder form. The negative electrode active material can reversibly store Li. The negative electrode active material can contain any component. The negative electrode active material is, for example, graphite, soft carbon, hard carbon, Si, Li silicate, SiO, Si-C, Si-based alloy, Sn, SnO, Sn-based alloy, and Li4Ti5O 12 and may contain at least one selected from the group consisting of.

[0058] "Si" may be, for example, amorphous or crystalline. Si can contain any crystal phase. Si may contain, for example, at least one selected from the group consisting of a diamond-type crystal phase, a clathrate I-type crystal phase, and a clathrate II-type crystal phase. "SiO" may have a composition represented by the general formula "SiO x (0.5 < x < 1.5)". "Si-C" indicates a composite material of carbon (C) and Si. For example, Si fine particles may be dispersed in carbon particles. For example, Si fine particles may be dispersed in graphite particles. For example, Li silicate particles may be coated with a carbon material (such as amorphous carbon).

[0059] In addition to the negative electrode active material, the negative electrode active material layer may further contain a solid electrolyte, a conductive material, and a binder. The conductive material may be the same or different between the negative electrode active material layer and the positive electrode active material layer.

[0060] The solid electrolyte layer (23) is interposed between the positive electrode active material layer and the negative electrode active material layer. The solid electrolyte layer (23) separates the positive electrode active material layer from the negative electrode active material layer. The solid electrolyte layer (23) may be equivalently referred to as, for example, a "separator layer". The solid electrolyte layer (23) contains a solid electrolyte. The solid electrolyte layer (23) may further contain, for example, a binder. The solid electrolyte and the binder may be the same or different between the solid electrolyte layer (23), the positive electrode active material layer, and the negative electrode active material layer.

[0061] [[ID=2**********]]-Restraining member- The restraining member 30 applies a restraining pressure (pressure) to the all-solid-state battery 20. The pressure can be applied along the thickness direction of the all-solid-state battery 20. The thickness direction of the all-solid-state battery 20 can be substantially the same direction as the stacking direction of the positive electrode layer 21, the solid electrolyte layer 23, and the negative electrode layer 22.

[0062] The restraining member 30 may have any structure. The restraining member 30 may be composed of, for example, a single member or multiple members. The restraining member 30 may be, for example, band-shaped. The restraining member 30 may include, for example, a first plate 31, a second plate 32, a bolt 33, and a nut 34. The all-solid-state battery 20 is disposed between the first plate 31 and the second plate 32. The first plate 31 and the second plate 32 have through holes formed therein. For example, the through holes may be formed in the four corners of each plate in a plan view. The bolt 33 is inserted into the through hole. The nut 34 is screwed onto the bolt 33. When the nut 34 is tightened, the first plate 31 and the second plate 32 pressurize the all-solid-state battery 20. That is, a restraining pressure is generated. The magnitude of the restraining pressure can be adjusted, for example, by the tightening torque of the nut 34. The restraining member 30 may be made of, for example, metal or resin.

[0063] The restraining member 30 has a breaking stress. The "breaking stress" refers to the limit of stress that the restraining member 30 can withstand without breaking when the force applied to the restraining member 30 gradually increases. The restraining member 30 is subjected to a reaction force from the all-solid-state battery 20. If the state quantity continues to increase after the transition of the state quantity changes to an increasing trend, the reaction force may exceed the breaking stress of the restraining member 30. The determination device 12 can determine the occurrence of an abnormality before the reaction force reaches the breaking stress, thereby preventing damage to the restraining member 30. That is, for example, the restraining member 30 may be configured so that the force applied to the restraining member 30 is less than the breaking stress when the relationship "(A1 / A0)<1.05," "(A1 / A0)<1.04," "(A1 / A0)<1.03," or "(A1 / A0)<1.02" is satisfied. "A0" indicates the initial value of the state quantity. "A1" indicates the current value of the state quantity. [Example]

[0064] -Preparing for all-solid-state batteries- A first composite is prepared by mixing a positive electrode active material (NCA), a sulfide solid electrolyte (10LiI-90[0.75Li2S-0.25P2S5]), a conductive material (VGCF), and a binder (PVdF). The first composite is pressed to form a positive electrode active material layer. The mixing ratio (mass ratio) of the first composite is "positive electrode active material: sulfide solid electrolyte: conductive material: binder = 85:13:1.3:0.7." The sulfide solid electrolyte contains a glass ceramic phase.

[0065] The sulfide solid electrolyte and the binder are mixed to prepare a second composite. The second composite is pressed to form a solid electrolyte layer (15 μm). The mixing ratio (mass ratio) of the second composite is "sulfide solid electrolyte:binder = 99.6:0.4."

[0066] A third composite is prepared by mixing a negative electrode active material (Si), a sulfide solid electrolyte, a conductive material, and a binder. The third composite is pressed to form a negative electrode active material layer. The mixing ratio (mass ratio) of the third composite is "negative electrode active material: sulfide solid electrolyte: conductive material: binder = 53:41:4.5:1.5." The D50 of Si is 2.5 μm. "D50" indicates the particle diameter at which the cumulative distribution reaches 50% in the volume-based particle size distribution (cumulative distribution). The particle size distribution can be measured by laser diffraction.

[0067] A positive electrode current collector (Al foil), a positive electrode active material layer, a solid electrolyte layer, a negative electrode active material layer, and a negative electrode current collector (Ni foil) are stacked in this order to form a laminate. The laminate is pressed to form a power generating element. Electrode terminals are connected to the power generating element. The power generating element is then housed in an exterior body to produce an all-solid-state battery.

[0068] -Measurement of state quantities- 4 is a conceptual diagram illustrating the experimental method. A first plate 31 and a second plate 32 are prepared. An all-solid-state battery 20 is placed between the first plate 31 and the second plate 32. A load cell 41 and a weight 42 are placed on the first plate 31. The weight 42 adjusts the confining pressure. A displacement sensor 43 is attached to the first plate 31 and the second plate 32.

[0069] The initial charge and discharge of the all-solid-state battery 20 is carried out in a thermostatic chamber set at 40°C. That is, the battery is charged from 0% SOC to 100% SOC by constant current-constant voltage (CCCV) charging. Next, the battery is discharged from 100% SOC to 0% SOC by CCCV discharging. The current rate during CC charging or CC discharging is 0.1C. The cutoff current during CV charging or CV discharging is 0.02C. "C" is the symbol representing the magnitude of the current rate. At a current rate of 1C, the rated capacity of the battery flows over one hour.

[0070] After the initial charge and discharge, charge and discharge are repeated using CCCV charging and CCCV discharging. One cycle consists of the following operations: CCCV charging charges the battery from 5% SOC to 95% SOC; CCCV discharging discharges the battery from 95% SOC to 5% SOC; the current rate during CC charging or CC discharging is 0.2C; the cutoff current during CV charging or CV discharging is 0.02C; the load cell 41 measures the pressure (confining pressure) at 95% SOC (upper SOC limit); and the displacement sensor 43 measures the thickness at 95% SOC.

[0071] -Measurement results- The thickness transition is shown in Figure 3. It can be seen that the thickness transition changes from a decreasing trend to an increasing trend. [Explanation of symbols]

[0072] 10 This system, 11 Detection device, 12 Judgment device, 20 All-solid-state battery, 21 Positive electrode layer, 22 Negative electrode layer, 23 Solid electrolyte layer, 25 Power generation element, 28 Exterior body, 30 Restraint member, 31 First plate, 32 Second plate, 33 Bolt, 34 Nut, 41 Load cell, 42 Weight, 43 Displacement sensor.

Claims

1. A system for determining the state of an all-solid-state battery, a detection device, and judgment device Including, the all-solid-state battery includes a positive electrode layer, a solid electrolyte layer, and a negative electrode layer in this order; the negative electrode layer contains a negative electrode active material, the detection device is configured to detect a state quantity, The state quantity includes at least one of an outer dimension of the all-solid-state battery and a confining pressure applied to the all-solid-state battery, and the determination device is configured to determine that an abnormality has occurred in the all-solid-state battery when the transition of the state quantity has changed from a decreasing trend to an increasing trend. system.

2. The negative electrode active material contains silicon. The system of claim 1 .

3. The determination device is such that 1.05≦(A 1 / A 0 ) is satisfied, the transition of the state quantity is determined to be on an increasing trend, The above A 0 indicates the initial value of the state quantity, and 1 indicates the current value of the state quantity, 3. The system according to claim 1 or claim 2.

4. the detection device is configured to detect the state quantity when the all-solid-state battery is being charged, and The determination device is configured to monitor a transition of the state quantity as the number of charging times increases.

3. The system according to claim 1 or claim 2.

5. A method for determining a state of an all-solid-state battery, (a) detecting a state quantity; and (b) determining that an abnormality has occurred in the all-solid-state battery when the transition of the state quantity changes from a decreasing trend to an increasing trend; Including, the all-solid-state battery includes a positive electrode layer, a solid electrolyte layer, and a negative electrode layer in this order; the negative electrode layer contains a negative electrode active material, the negative electrode active material contains silicon, the state quantity includes at least one of an outer dimension of the all-solid-state battery and a confining pressure applied to the all-solid-state battery, the state quantity is detected during charging of the all-solid-state battery, A transition of the state quantity with an increase in the number of charging times is monitored; 1.05≦(A 1 / A 0 ) is satisfied, it is determined that the transition of the state quantity is on the increase, and 0 indicates the initial value of the state quantity, and 1 indicates the current value of the state quantity, method.

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