Solid-state battery and method of manufacturing solid-state battery

Abstract

The present invention relates to a solid-state battery in which a heat dissipation material is contained between an electrode body and an outer body, and in an environment of 25°C, a current value of 0.5 C is set, and a cycle test is performed in which a charging rate from 0% to 100% and a discharging rate from 100% to 0% is performed as one cycle, and this cycle is repeated 200 times, and then when the heat dissipation material is discharged to 0% after being charged to 100%, the heat dissipation material is in contact with both the electrode body and the outer body, and a method for manufacturing the solid-state battery.

Description

Technology Field

[0001] The present disclosure relates to a solid-state battery and a method for manufacturing a solid-state battery. Background Technology

[0002] Recently, the demand for secondary batteries has been rising, and in addition to secondary batteries equipped with liquid electrolytes, the development of solid-state batteries using solid electrolytes is underway. An example of a solid-state battery is the all-solid-state battery, which features a solid electrolyte layer instead of a liquid electrolyte. Since it does not use flammable organic solvents, it allows for the simplification of safety devices and offers excellent manufacturing costs and productivity.

[0003] An all-solid-state battery cell capable of obtaining a battery module with good cooling efficiency is known, wherein, on the bottom surface of the battery cell, a first thermal material is disposed in contact with an electrode laminate and an outer material on the inner side of the outer material (Patent Document 1). Prior art literature

[0004] Japanese Patent Publication No. 2020-113496 The problem to be solved

[0005] In solid-state batteries, the heat dissipation material effectively provides a cooling effect on the electrode body by remaining in contact with the electrode body and the outer casing. Therefore, it is desirable for the heat dissipation material to maintain contact with the electrode body and the outer casing without delaminating from the electrode body or the outer casing, even when the electrode body expands or contracts. However, since the volume change characteristics of the electrode body, such as expansion and contraction, vary depending on the electrode body's material, the heat dissipation material may delaminate from the electrode body or the outer casing depending on the type of electrode body. Consequently, it has been desired for the heat dissipation material to maintain contact with the electrode body and the outer casing, even with electrode bodies of different types.

[0006] The problem that one embodiment of the present disclosure aims to solve is to provide a solid-state battery and a method for manufacturing a solid-state battery, which maintain a state in which a heat dissipation material is in contact with an electrode body and an outer body with high reliability, regardless of the type of electrode body. means of solving the problem

[0007] The means for solving the problem include the following modes.

[0008] <1> A solid-state battery in which a heat dissipation material is contained between an electrode body and an outer body, and in an environment of 25°C, a current value of 0.5 C is set, and a cycle is performed such that a charge from a charge rate of 0% to 100% and a discharge from a charge rate of 100% to 0% constitutes one cycle, and the cycle is repeated 200 times; wherein, when the charge rate is charged to 100% and then discharged to 0%, the heat dissipation material is in contact with both the electrode body and the outer body.

[0009] <2> The heat dissipation material is a solid-state battery described in <1> comprising a resin or an elastomer.

[0010] <3> A solid-state battery as described in <2>, comprising at least one resin selected from silicone resin and acrylic resin.

[0011] <4> A solid-state battery described in any one of <1> to <3>, wherein the heat dissipation material comprises a filler, and the filler comprises at least one type selected from ceramic filler and metal filler.

[0012] <5> A solid-state battery described in any one of <1> to <4>, wherein the heat dissipation material has a compressive permanent deformation value smaller than the compressive permanent deformation value of a reference heat dissipation material satisfying condition 1 below.

[0013] Condition 1: The reference heat dissipation material is in contact with both the electrode body and the outer body when an unused solid-state battery, in which the reference heat dissipation material is contained between the electrode body and the outer body, is charged to a charge rate of 100% and then discharged to a charge rate of 0%.

[0014] <6> The heat dissipation material is a solid-state battery described in any one of <1> to <5>, having a thermal conductivity of less than 11.5 W / m·K and a compressive permanent deformation of less than 98.8%.

[0015] <7> The heat dissipation material is a solid-state battery described in any one of <1> to <6> having electrical insulation properties.

[0016] <8> A solid-state battery described in any one of <1> to <7>, which is a prismatic battery.

[0017] <9> A solid battery described in any one of <1> to <8>, wherein the outer body has a rectangular shape and the surface in contact with the heat dissipation material forms a convex shape toward the interior of the solid battery.

[0018] <10> A solid-state battery described in any one of <1> to <9>, which is an all-solid-state battery.

[0019] <11> A method for manufacturing a solid-state battery in which an electrode body and a heat dissipation material are housed in an outer body, comprising the steps of: housing the electrode body and the heat dissipation material in an outer body such that the heat dissipation material contacts both sides of the electrode body and the outer body; and compressing the heat dissipation material by pressing the electrode body in the direction of the stacking axis of the electrode body and the heat dissipation material, wherein the heat dissipation material comprises a material satisfying the following condition 2.

[0020] Condition 2: In a solid-state battery in which a heat dissipation material is accommodated between an electrode body and an outer body, under an environment of 25°C, the current value is set to 0.5 C, and a cycle test is performed in which charging from a charge rate of 0% to 100% and discharging from a charge rate of 100% to 0% is performed as one cycle, and the cycle is repeated 200 times. After charging to a charge rate of 100% and then discharging to a charge rate of 0%, the heat dissipation material is in contact with both the electrode body and the outer body.

[0021] <12> Additionally, a method for manufacturing a solid-state battery as described in <11>, comprising a process of encapsulating an electrode body and a heat dissipation material in an outer body while the heat dissipation material is compressed.

[0022] <13> A method for manufacturing a solid-state battery as described in <11> or <12>, having a process of deforming the surface of the outer body that contacts the heat dissipation material by applying pressure to the outer body toward the heat dissipation material.

[0023] <14> A method for manufacturing a solid-state battery as described in any one of <11> to <13>, wherein additionally, a process of injecting a heat dissipation material into the gap between the electrode body and the outer body. Effects of the invention

[0024] According to one embodiment of the present disclosure, a solid-state battery and a method for manufacturing a solid-state battery are provided, which maintain a state in which a heat dissipation material is in contact with an electrode body and an outer body with high reliability, regardless of the type of electrode body. Brief explanation of the drawing

[0025] FIG. 1 is a schematic cross-sectional view of a solid-state battery illustrating the arrangement of electrodes, heat dissipation materials, and outer casings in a solid-state battery, and is a schematic cross-sectional view of the solid-state battery cut in a plane parallel to the stacking axis direction (X). FIG. 2 is a schematic cross-sectional view of a solid battery explaining that the surface in contact with the heat dissipation material of the outer body forms a convex shape toward the interior of the solid battery, and is a schematic cross-sectional view of the solid battery cut in a plane parallel to the stacking axis direction (X). FIG. 3a is a schematic cross-sectional view of a solid-state battery illustrating the encapsulation process, which is a schematic cross-sectional view of the solid-state battery cut in a plane parallel to the stacking axis direction (X). FIG. 3b is a schematic cross-sectional view of a solid-state battery illustrating a compression process, which is a schematic cross-sectional view of the solid-state battery cut in a plane parallel to the stacking axis direction (X). FIG. 3c is a schematic cross-sectional view of a solid-state battery illustrating a heat dissipation material that follows the volume change of an electrode body, and is a schematic cross-sectional view of the solid-state battery cut in a plane parallel to the stacking axis direction (X). FIG. 4 is a schematic cross-sectional view of a solid-state battery illustrating an injection process, which is a schematic cross-sectional view of the solid-state battery cut along a plane parallel to the stacking axis direction (X). Specific details for implementing the invention

[0026] In the present disclosure, a numerical range indicated by "~" means a range that includes the values ​​described before and after "~" as the minimum and maximum values, respectively.

[0027] In the numerical ranges described stepwise in the present disclosure, an upper or lower limit value described in any numerical range may be substituted with an upper or lower limit value of a numerical range described in another stepwise manner. In the numerical ranges described in the present disclosure, an upper or lower limit value described in any numerical range may be substituted with a value shown in an example.

[0028] In the present disclosure, the term “process” includes not only independent processes but also cases where the process cannot be clearly distinguished from other processes, provided that the intended purpose of the process is achieved.

[0029] In the present disclosure, a combination of two or more preferred embodiments is a more preferred embodiment.

[0030] When embodiments of the present disclosure are described with reference to the drawings, the configuration of said embodiment is not limited to the configuration shown in the drawings. Furthermore, the sizes of the components in each drawing are conceptual, and the relative relationships of the sizes between the components are not limited thereto.

[0031] In the present disclosure, "charge level" includes state of charge (SOC) and other conventional indicators representing the charge state of a battery.

[0032] <Solid-state Battery>

[0033] A solid-state battery, which is an embodiment of the present disclosure, will be described using FIGS. 1 and 2.

[0034] A solid-state battery related to one embodiment of the present disclosure (hereinafter also referred to as a solid-state battery or battery) is a solid-state battery in which a heat dissipation material is contained between an electrode body and an outer body, and under an environment of 25°C, a current value of 0.5 C is set, and a cycle test (hereinafter also referred to as a specific cycle test) is performed in which a charging rate from 0% to 100% and a discharging rate from 100% to 0% are performed as one cycle, and the cycle is repeated 200 times, and when the charging rate is discharged to 0% after being charged to 100%, the heat dissipation material is in contact with both the electrode body and the outer body.

[0035] The above heat dissipation material is highly likely to maintain contact with the electrode and the outer casing with high reliability from the beginning to the end of battery use, regardless of the type of electrode. Therefore, the reduction in the cooling effect of the heat dissipation material caused by peeling off from the electrode or the outer casing can be suppressed, and the cooling performance of the battery can be secured.

[0036] The inventors investigated cases where the heat dissipation material peels off from the inner surface of the outer casing or the surface of the electrode during use, as the expansion rate and contraction rate of the electrode vary depending on the material constituting the electrode, and the heat dissipation material cannot keep up with the volume change of the electrode within the battery. They also focused on physical properties such as permanent compressive deformation of the heat dissipation material that follow the space between the electrode and the outer casing. Furthermore, they discovered that when the heat dissipation material is in contact with both the electrode and the outer casing after a specific cycle test, and then discharged to a charge rate of 0% after charging to 100%, the heat dissipation material maintains contact with the electrode and the outer casing with high reliability, regardless of the type of electrode.

[0037] Although the mechanism by which the heat dissipation material can maintain contact with the electrode body and the outer body within the battery with higher reliability, regardless of the type of electrode body, is not clear, it is presumed that this is because, after a specific cycle test, when the heat dissipation material is in contact with both the electrode body and the outer body after being charged to 100% and then discharged to 0%, there is a high probability that the contact state will continue until the end of the battery's use. Furthermore, for example, since the value of the compressive permanent deformation of the heat dissipation material reflects the shape characteristics of the heat dissipation material to some extent even when it is pressurized by the electrode body and accommodated in the solid-state battery, it is presumed that by using the value of the compressive permanent deformation, the likelihood of the heat dissipation material maintaining contact until the end of the battery's use increases, regardless of the type of electrode body.

[0038] As shown in FIG. 1, the solid-state battery (10) has an electrode body (11) and a heat dissipation material (15) housed in an outer body (13). The heat dissipation material (15) is placed between the electrode body (11) and the outer body (13), in contact with both sides of the electrode body (11) and the outer body (13). That is, the electrode body (11), the heat dissipation material (15), and the outer body (13) are stacked. Thus, the electrode body (11), the heat dissipation material (15), and the outer body (13) are thermally bonded. Therefore, the heat generated by the electrode body (11) is transferred to the heat dissipation material (15) and the outer body (13), which are heat transfer bodies, thereby cooling the electrode body (11). Additionally, the stacking axis direction of the electrode body (11) and the heat dissipation material (15) is direction X. One heat dissipation material (15) is accommodated at each end in the stacking axis direction (X) of the electrode body (11).

[0039] (Heat dissipation material)

[0040] The heat dissipation material is a material that has the function of transferring heat generated by the electrode to the outer body and cooling the electrode by thermally bonding with the electrode and the outer body. After a specific cycle test of the solid-state battery, when the battery is charged to a charge rate of 100% and then discharged to a charge rate of 0%, the heat dissipation material is in contact with both the electrode and the outer body.

[0041] A cycle test for a lithium secondary battery is intended to verify the durability of the battery when it undergoes repeated charging and discharging. A specific cycle test for a solid-state battery can be performed using the method described below. Specifically, under an environment of 25°C, with a current value of 0.5 C, a specific cycle test is defined as a test in which a charging rate from 0% to 100% and a discharging rate from 100% to 0% constitute one cycle, and the cycle is repeated 200 times. Through the specific cycle test, the durability after charge-discharge cycles can be appropriately evaluated.

[0042] The charge rate (i.e., State of Charge, SOC) is an indicator representing the charge state of a battery and is a numerical value indicating the ratio of the amount of power accumulated in the battery to the maximum capacity of the battery. 0% indicates a completely discharged state, and 100% indicates a fully charged state. In addition, the charge rate can be measured by conventionally known methods, and for example, it can be measured using the Open Circuit Voltage (OCV) obtained for a solid-state battery.

[0043] When the heat dissipation material is discharged to a charge rate of 0% after being charged to a charge rate of 100% following a specific cycle test, the heat dissipation material is in contact with both the electrode body and the outer body. Since the heat dissipation material satisfies the above conditions, regardless of the type of electrode body, there is a high probability that the contact of the heat dissipation material with the electrode body and the outer body will continue with high reliability from the beginning to the end of battery use.

[0044] The statement that the heat dissipation material is in contact with both the electrode body and the outer body means that the main surface of one side of the heat dissipation material has an area that contacts at least the electrode body, and the main surface of the other side of the heat dissipation material has an area that contacts at least the outer body. It is preferable that the contact area between the main surface of one side of the heat dissipation material and the electrode body is larger. In addition, it is preferable that the contact area between the main surface of the other side of the heat dissipation material and the outer body is larger.

[0045] The heat dissipation material preferably comprises a resin or an elastomer in order to maintain contact between the heat dissipation material and the electrode body and the outer body. Specifically, the heat dissipation material preferably uses a resin blended with a filler or an elastomer blended with a filler. The resin, filler, or elastomer may be one that is conventionally known as a heat dissipation material for solid-state batteries. Furthermore, the elastomer refers to a polymer material having elasticity, and specifically, examples include thermoplastic elastomers.

[0046] As for the resin, examples include silicone resin, acrylic resin, epoxy resin, etc., in terms of maintaining a state where the heat dissipation material is in contact with the electrode body and the outer body, and it is preferable to include at least one type selected from silicone resin and acrylic resin.

[0047] Examples of fillers include metal fillers and ceramic fillers, from the perspective of maintaining the state in which the heat dissipation material contacts the electrode body and the outer body. As for the ceramic filler, it is preferable to include at least one type selected from metal oxides and metal nitrides. Examples of metal fillers include copper and aluminum. Examples of ceramic fillers include alumina, silica, aluminum nitride, boron nitride, etc. By using ceramic fillers, the electrical insulation properties of the heat dissipation material can be improved. In the heat dissipation material, the above physical properties, such as compression permanent deformation, thermal conductivity, and electrical insulation properties, can be adjusted by the type of filler, the mixing ratio, etc.

[0048] In heat dissipation materials, thermal conductivity and hardness tend to increase with an increase in the amount of filler added. Since a heat dissipation material that is excessively soft tends to be crushed, the harder the material, the lower the compression permanent deformation tends to be. However, if the heat dissipation material is too hard, problems may arise, such as the resin becoming prone to fracture or it becoming difficult to form a sheet shape. Therefore, to suppress the increase in hardness caused by the addition of fillers, it is desirable to control the hardness by reducing the molecular weight of the resin or by softening the resin itself.

[0049] It is desirable that the heat dissipation material has a value of compressive permanent deformation smaller than the value of compressive permanent deformation of a reference heat dissipation material satisfying condition 1 below, in order to maintain the state in which the heat dissipation material is in contact with the electrode body and the outer body.

[0050] Condition 1: The reference heat dissipation material is in contact with both the electrode body and the outer body when an unused solid-state battery, in which the reference heat dissipation material is contained between the electrode body and the outer body, is charged to a charge rate of 100% and then discharged to a charge rate of 0%.

[0051] In Condition 1, it is preferable that the electrode body and the outer body of the solid-state battery in which the reference heat dissipation material is received are of the same type as the electrode body and the outer body of the solid-state battery in which the heat dissipation material is received.

[0052] Regarding the heat dissipation material, in the case of a heat dissipation material contained in a solid-state battery, it is preferable that the value of the compressive permanent deformation of the heat dissipation material extracted from the solid-state battery satisfies the above condition 1, but it is also acceptable for the value of the compressive permanent deformation before containing the heat dissipation material in the solid-state battery to satisfy the above condition 1. When selecting a heat dissipation material that follows the volume change accompanying charging and discharging different for each type of electrode body, by measuring the compressive permanent deformation of the heat dissipation material, a heat dissipation material that is highly likely to maintain a state in which the heat dissipation material is in contact with the electrode body and the outer body when contained in the solid-state battery can be selected.

[0053] The compression permanent deformation of the heat dissipation material or the reference heat dissipation material may be the value of the compression permanent deformation measured by the following measurement method. That is, the compression permanent deformation CS of the heat dissipation material is preferably a value calculated by the following Equation (1) using the value measured by compressing the heat dissipation material by 25% in thickness along the stacking axis direction of the electrode body, maintaining it at 25°C for 1 minute, and then releasing the compression, from the perspective of the reliability of the contact state of the heat dissipation material. In addition, the size of the test specimen may be, for example, a square with initial dimensions of 15 mm in length and width and a thickness of 2 mm. In addition, it is preferable to have multiple measurement points on the test specimen and to use the average value of these as the measurement result. The specific measurement method for compression permanent deformation is not limited to the above examples and may vary depending on the type of heat dissipation material, for example. The measurement of compression permanent deformation may be performed in accordance with JIS K6262.

[0054] Compressive permanent deformation CS = {(h0 - h1) / (h0 - h s )} × 100 (1)

[0055] In Equation (1),

[0056] h0 is the thickness of the heat dissipation material in the stacking axis direction before compression (unit: mm), and

[0057] h1 is the thickness of the heat dissipation material in the stacking axis direction after opening the compression (unit: mm), and

[0058] h s is the thickness of the heat dissipation material in the stacking axis direction during compression (unit: mm).

[0059] It is desirable that the heat dissipation material has a thermal conductivity of less than 11.5 W / m·K and a compression permanent deformation of less than 98.8%, from the perspective of heat dissipation function and maintaining a state in which the heat dissipation material is in contact with the electrode body and the outer body.

[0060] Compression permanent deformation is more preferably 95% or less from the perspective of maintaining the state in which the heat dissipation material is in contact with the electrode body and the outer body. Regarding thermal conductivity, from the perspective of the heat dissipation material properly performing a heat dissipation function, it is more preferable that the thermal conductivity is less than 8 W / m·K, more preferable that it is less than 6 W / m·K, and particularly preferable that it is less than 4 W / m·K. In addition, regarding the heat dissipation material properly performing a heat dissipation function, it is preferable that the thermal conductivity of the heat dissipation material be greater than 2 W / m·K. The thermal conductivity of the heat dissipation material can be adjusted by the composition of the heat dissipation material, etc.

[0061] The thermal conductivity of the heat dissipation material is a value measured by the heat flow meter method in accordance with ASTM E 1530. Compression permanent deformation can be measured by the measurement method described above.

[0062] It is desirable for heat dissipation materials to possess electrical insulation properties from the perspective of battery safety. By having electrical insulation properties, short circuits in solid-state batteries can be prevented. The electrical insulation properties of a heat dissipation material can be determined by various indicators such as dielectric breakdown strength, volume resistivity, and dielectric constant. The electrical insulation properties of a heat dissipation material can be adjusted by the composition of the material. For example, as mentioned above, electrical insulation properties can be imparted by the type of filler included in the heat dissipation material.

[0063] When using dielectric breakdown strength, a case where the dielectric breakdown strength of the heat dissipation material is 10 kV / mm or higher may be considered to have electrical insulation properties. It is more preferable that the dielectric breakdown strength be 15 kV / mm or higher, and even more preferable that it be 20 kV / mm or higher. In addition, when using volume resistivity, the volume resistivity of the heat dissipation material is 10 12 If it exceeds Ω·cm, it can be used as a heat dissipation material having electrical insulation properties. In addition, when using surface resistivity, if the surface resistivity of the heat dissipation material is 10 12 In cases where Ω / □ is exceeded, a heat dissipation material having electrical insulation properties can be used.

[0064] The shape of the heat dissipation material varies depending on the type of solid-state battery, but from the perspective of maintaining the state in which the heat dissipation material contacts the electrode body and the outer body, for example, the initial thickness is preferably 0.5 mm to 4.0 mm, more preferably 0.8 mm to 3.7 mm, and even more preferably 1.7 mm to 3.2 mm. In addition, when placed inside the solid-state battery, the thickness of the heat dissipation material in a state where it is pressed and adhered in the direction of the outer body by the electrode body is preferably 0.20 mm to 3.8 mm, more preferably 0.5 mm to 3.5 mm, and even more preferably 1.0 mm to 3.0 mm.

[0065] In a solid-state battery, it is preferable that the heat dissipation material be in contact with both the electrode body and the outer body. By having the heat dissipation material in contact with both the electrode body and the outer body, the heat dissipation material can maintain contact with the electrode body and the outer body, thereby ensuring cooling performance. Since the heat dissipation material is a material that is in contact with both the electrode body and the outer body when the battery is discharged to a charge rate of 0% after charging to 100% following a specific cycle test, it is highly likely that the heat dissipation material will continuously maintain contact with the electrode body and the outer body regardless of the type of electrode body, and regardless of the charging state of the battery, i.e., the degree of charging or discharging of the battery, or the number of charge and discharge cycles. Therefore, in a solid-state battery, the heat dissipation material can maintain contact with the electrode body and the outer body with high reliability, thereby maintaining cooling performance.

[0066] (Electrode body)

[0067] The electrode body may be a conventionally known electrode body used in solid-state batteries. Solid-state batteries include semi-solid-state batteries and all-solid-state batteries. Any type of electrode body used in solid-state batteries may be used. For example, the electrode body is an electrode body in which a negative electrode layer, a negative electrode layer, an electrolyte layer, a positive electrode layer, and a positive electrode layer are stacked in this order. In a solid-state battery, the electrode body may expand or contract as the electrode active material contained in the negative electrode layer or the positive electrode layer expands or contracts due to charging and discharging. However, in a solid-state battery of one embodiment of the present disclosure, by using the heat dissipation material described above, the heat dissipation material follows the expansion or contraction of the electrode body regardless of the type of electrode body, thereby maintaining a state of contact between the electrode body and the outer casing. Therefore, the cooling performance of the battery can be secured regardless of the type of electrode body. It is preferable that the electrode body be an electrode body used in all-solid-state batteries. The effect of a solid-state battery according to one embodiment of the present disclosure is more effective when the electrode body is used in an all-solid-state battery, in terms of volume change due to expansion or contraction of the electrode body.

[0068] (Exterior body)

[0069] The outer casing is equipped with the function of isolating the internal material of the battery from the external environment to ensure the safety and stability of the battery, and the function of cooling the electrode body by thermally bonding with the heat dissipation material. Regarding the shape and material, the outer casing may utilize a conventionally known outer casing used in solid-state batteries. From the perspective of compressing the heat dissipation material, it is preferable for the outer casing to have a prismatic shape. Accordingly, it is preferable for the solid-state battery to be a prismatic battery. By having a prismatic shape, the electrode body and the heat dissipation material located inside the outer casing are preferably compressed by the deformation of at least one of the electrode body and the outer casing.

[0070] The outer body preferably has a rectangular shape, and the surface in contact with the heat dissipation material is preferably convex toward the interior of the solid-state battery. The surface in contact with the heat dissipation material is a surface that intersects the stacking axis direction in the outer body and is a surface that contacts the main surface of the heat dissipation material. Due to such a convex surface of the outer body, the electrode body can be effectively kept in a pressurized state even if there is a change in the volume of the electrode body inside the battery, and the adhesion between the electrode body, the heat dissipation material, and the outer body can be improved.

[0071] As shown in FIG. 2, in a solid battery (20), the surface (24) in contact with the heat dissipation material (22) of the outer body (23) forms a convex shape toward the interior of the solid battery (20). In the manufacture of the solid battery (20), the electrode body (21) and the heat dissipation material (22) are first accommodated in the outer body (23) having a rectangular shape. The heat dissipation material (22) is placed between the electrode body (21) and the outer body (23). After the electrode body (21) and the heat dissipation material (22) are sealed within the outer body (23) to form a solid battery (20), the surface (24) in contact with the heat dissipation material (22) of the outer body (23) is molded to form a convex shape toward the interior of the solid battery (20). Specifically, force is applied from the outer surface of the outer body (23) in the direction indicated by the white arrow, so that the surface (24) is formed to be indented toward the interior of the solid battery (20). Due to the convex shape of the surface (24), the electrode body (21) is effectively pressed, and the heat dissipation material (22) is compressed, so that the electrode body (21) and the outer body (23) are more firmly attached.

[0072] (Types of solid-state batteries)

[0073] The type of solid-state battery is not particularly limited, but is typically a lithium-ion battery. Furthermore, the solid-state battery of one embodiment of the present disclosure is preferably a secondary battery. This is because it can be repeatedly charged and discharged, and is useful, for example, as a battery for vehicles. The solid-state battery may be a semi-solid-state battery or an all-solid-state battery.

[0074] It is preferable that the solid-state battery be an all-solid-state battery. In all-solid-state batteries, depending on the type of active material included in the electrode layer, the expansion and contraction during charging and discharging may be large, resulting in significant volume changes in the electrode body. Therefore, the effect of maintaining a state in which the heat dissipation material contacts the electrode body and the outer casing with high reliability, regardless of the type of electrode body, as provided by the solid-state battery of one embodiment of the present disclosure, is more effective when the solid-state battery is an all-solid-state battery.

[0075] <Method for manufacturing a solid-state battery>

[0076] A method for manufacturing a solid-state battery, which is an embodiment of the present disclosure, will be explained using FIGS. 3a to 4.

[0077] A method for manufacturing a solid-state battery according to one embodiment of the present disclosure is a method for manufacturing a solid-state battery in which an electrode body and a heat dissipation material are accommodated in an outer body, and comprises a receiving process and a compression process. The receiving process is a process of accommodating the electrode body and the heat dissipation material in an outer body such that the heat dissipation material comes into contact with both sides of the electrode body and the outer body. The compression process is a process of compressing the heat dissipation material by pressing the electrode body in the direction of the stacking axis of the electrode body and the heat dissipation material. The heat dissipation material includes a material that satisfies the following condition 2.

[0078] Condition 2: In a solid-state battery in which the material is accommodated between the electrode body and the outer body, after a specific cycle test, the material is in contact with both the electrode body and the outer body when the charge rate is charged to 100% and then discharged to 0%.

[0079] (Acceptance Process)

[0080] The receiving process is a process of receiving an electrode body and a heat dissipation material into an outer body such that the heat dissipation material is positioned between the electrode body and the outer body. In the receiving process, for example, in a box-shaped outer body having an opening on one side, the heat dissipation material is received first through the opening, and then the electrode body is received through the opening. In this way, the electrode body and the heat dissipation material can be received into the outer body such that the heat dissipation material is positioned between the electrode body and the outer body.

[0081] (Compression process)

[0082] The compression process is a process of compressing a heat dissipation material. For example, when housing an electrode body and a heat dissipation material in an outer body, after housing the heat dissipation material in the outer body, the heat dissipation material is pressed into the outer body by pressing the electrode body in the direction of the stacking axis. This improves the adhesion between the electrode body, the heat dissipation material, and the outer body. Although the compression of the heat dissipation material varies depending on the type of solid-state battery, for example, based on the thickness of the heat dissipation material in the direction of the stacking axis before compression, it is preferable to be 5% to 60%, more preferable to be 10% to 50%, and even more preferable to be 15% to 40%. Through the compression process, the heat dissipation material adheres to both the electrode body and the outer body, and the thickness in the direction of the stacking axis (direction X in FIG. 3b) is reduced.

[0083] In the receiving process, a heat dissipation material (15) is received in the outer body (13) through an opening in the outer body (13), and the heat dissipation material is received so as to be in contact with the surface (14) that is in contact with the heat dissipation material (15), which is one side of the outer body (13) (see FIG. 3a). After that, an electrode body (11) is received through the opening. The opening of the outer body (13) is formed, for example, on the surface facing the surface (14) of the outer body (13). In the compression process that follows the receiving process, the heat dissipation material (15) is compressed by pressing the electrode body (11) in the direction of the stacking axis of the electrode body (11), the heat dissipation material (15), and the outer body (13) (see FIG. 3b). By the compression process, the heat dissipation material (15) is adhered to both the electrode body (11) and the outer body (13).

[0084] Additionally, the heat dissipation material (15) can follow the volume change of the electrode body (11). As shown in FIG. 3c, even if the electrode body (11) shrinks, the heat dissipation material (15) maintains contact with the electrode body (11) and the outer body (13) by following the shrinkage of the electrode body (11) as it changes from thickness a to thickness b in the stacking axis direction (X).

[0085] The heat dissipation material includes a material that satisfies Condition 2. Condition 2 is a condition satisfied by the material included in the heat dissipation material. By manufacturing a solid-state battery using a heat dissipation material that includes a material satisfying Condition 2, it is possible to manufacture a solid-state battery in which the heat dissipation material maintains contact with the electrode body and the outer body with high reliability, regardless of the type of electrode body.

[0086] In Condition 2, it is preferable that the electrode body and the outer body of the solid-state battery in which the material is received are of the same type as the electrode body and the outer body of the solid-state battery in which the heat dissipation material is received. In Condition 2, in the solid-state battery manufactured using the electrode body and the outer body, after a specific cycle test, when the charge rate is charged to 100% and then discharged to 0%, the material is in contact with both the electrode body and the outer body. The details of the material are the same as the heat dissipation material described above.

[0087] (Encapsulation process)

[0088] After the compression process, it is preferable to have a sealing process in which the electrode body and the heat dissipation material are sealed into an outer body while the heat dissipation material is in a compressed state. By sealing the heat dissipation material into the outer body while it is in a compressed state, the electrode body, the heat dissipation material, and the outer body can be maintained in a state of close contact, and the electrode body can be effectively pressurized. Specifically, the sealing can be performed by closing the opening of the outer body while the electrode body is in a state of compressing the heat dissipation material.

[0089] (Deformation process)

[0090] After the sealing process, it is desirable to have a deformation process in which the surface of the outer body in contact with the heat dissipation material is deformed by applying pressure to the outer body toward the heat dissipation material. This increases the adhesion between the electrode body, the heat dissipation material, and the outer body, and makes the pressure state of the electrode body more favorable. In the deformation process, it is desirable to deform the surface of the outer body in contact with the heat dissipation material so that it forms a convex shape toward the inside of the battery (see FIG. 4).

[0091] (Injection process)

[0092] After the sealing process, it is preferable to have an injection process in which a heat dissipation material is injected into the gap between the electrode body and the outer body. This is desirable because the heat dissipation material is injected into the gap between the electrode body and the outer body, and by making the gap between the electrode body and the outer body as small as possible, the adhesion between the electrode body and the heat dissipation material is improved by the expansion of the electrode body, and the heat from the electrode body can be transferred to the outer body by the heat dissipation material over a wider area. As shown in FIG. 4, in the injection process, a heat dissipation material is injected into the gap (31) between the electrode body (21) and the outer body (23).

[0093] It is preferable that the outer body has a prismatic shape and that the surface in contact with the heat dissipation material forms a convex shape toward the interior of the solid-state battery. It is desirable that the outer body has a prismatic shape because it makes it easier to adhere the heat dissipation material to one surface of the outer body during the compression process. Additionally, because the outer body has a prismatic shape, the adhesion between the electrode body, the heat dissipation material, and the outer body can be improved more effectively by deforming the surface in contact with the heat dissipation material of the outer body to form a convex shape toward the interior of the battery during the deformation process (see FIG. 2 or FIG. 4).

[0094] After the sealing process, it is preferable to perform at least one of the deformation process and the injection process. Either the deformation process or the injection process may be performed, or both may be performed. If both the deformation process and the injection process are performed, the order does not matter, but it is preferable to perform the deformation process after the injection process. This is because the effect of the deformation process is more effectively manifested.

[0095] <Applications of Solid-State Batteries>

[0096] Applications for solid-state batteries include, for example, power sources for vehicles such as hybrid electric vehicles (HEV), plug-in hybrid electric vehicles (PHEV), electric vehicles (BEV), gasoline cars, and diesel cars. In particular, it is desirable to use them as power sources for driving hybrid electric vehicles (HEV), plug-in hybrid electric vehicles (PHEV), or electric vehicles (BEV). In addition, solid-state batteries may be used as power sources for mobile bodies other than vehicles (e.g., railways, ships, aircraft) and as power sources for electrical products such as information processing devices.

[0097] Examples

[0098] The present disclosure will be explained in more detail below with reference to examples. The scope of the present disclosure is not limited to the examples shown below.

[0099] (Heat dissipation material)

[0100] Various heat dissipation materials, heat dissipation material 1 to heat dissipation material 6, were prepared. Heat dissipation materials 1 to 6 had different compositions, as the type of resin or elastomer included, the type and content of the filler, etc. For each of heat dissipation materials 1 to 6, the compression permanent deformation CS (%) was measured by the method described below.

[0101] Each heat dissipation material was prepared in the form of a sheet with initial dimensions of 15 mm in length and 15 mm in width. A 0.1 mm thick PET (polyethylene terephthalate) sheet was placed on one side and the other side of each sheet-shaped heat dissipation material, respectively, and compressed in the thickness direction. The measurement conditions for the compression permanent deformation CS (%) were as follows: the heat dissipation material was compressed to a compression ratio of 25% in the thickness direction, maintained at 25°C for 1 minute, and then the compression was released to measure the thickness. The thickness of the heat dissipation material in the stacking axis direction before compression (unit: mm) is h0, the thickness of the heat dissipation material in the stacking axis direction after releasing compression (unit: mm) is h1, and the thickness of the heat dissipation material in the stacking axis direction during compression (unit: mm) is h s Thus, the value calculated by the following equation (1) was set as the compressive permanent deformation CS.

[0102] Compressive permanent deformation CS = {(h0 - h1) / (h0 - h s )} × 100 (1)

[0103]

[0104] The composition and physical properties of each of heat dissipation materials 1 to 6 are listed in Table 2.

[0105] In Table 2, the thermal conductivity (W / m·K) is a value measured by the heat flow meter method based on ASTM E1530. The Young's modulus (MPa) is a value measured by the tensile test based on JIS K7162. The hardness (Asker C) is a value measured by the Asker rubber hardness tester Type C. The specific gravity is a value measured by the underwater displacement method based on JIS K7112.

[0106]

[0107] (Electrode body)

[0108] 1. Electrode A

[0109] Electrode body A is an electrode body used in an all-solid-state battery, and was manufactured by stacking a negative electrode layer, a negative electrode layer, an electrolyte layer, a positive electrode layer, and a positive electrode layer in this order. The dimensions were a rectangular body with a length of 100 mm, a width of 280 mm, and a thickness of 20 mm.

[0110] 2. Electrode B

[0111] Electrode B was manufactured in the same manner as electrode A, except that the positive electrode material and negative electrode material were different from electrode A.

[0112] (Exterior body)

[0113] The outer body was a rectangular can formed using aluminum material, and its dimensions were 105 mm in height, 300 mm in width, and 0.3 mm in thickness.

[0114] <Examples 1 to 7 and Comparative Examples 1 to 5>

[0115] Using the above-mentioned heat dissipation materials 1 to 6, electrode body A or electrode body B, and an outer body, a receiving process and a compression process were performed to manufacture each solid-state battery.

[0116] (evaluation)

[0117] For each solid-state battery, in each of the following steps (a) to (c), the computed tomography images of the heat dissipation material when the solid-state battery was charged to a charge rate of 100% and then discharged to a charge rate of 0% were observed visually. The evaluation criteria are listed in Table 3. In the evaluation criteria, A was deemed acceptable.

[0118] (Step a): When the solid-state battery is not in use

[0119] (Step b): After conducting a specific cycle test

[0120] (Step c): After conducting a specific cycle test, and after conducting an additional specific cycle test, that is, after conducting the specific cycle test two consecutive times

[0121] The specific cycle test was conducted on each solid-state battery, and under an environment of 25°C, the current value was set to 0.5 C, and one cycle was defined as charging from 0% to 100% and discharging from 100% to 0%, and the cycle was repeated 200 times.

[0122] =Evaluation Criteria=

[0123] A: The heat dissipation material is in contact with both the electrode body and the outer body.

[0124] B: The heat dissipation material is in contact with only either the electrode body or the outer body.

[0125] C: The heat dissipation material is not in contact with both the electrode body and the outer body.

[0126]

[0127] [Head of process] The Explanation of the symbols

[0128] 10, 20: Solid-state battery 11, 21: Electrode 13, 23 : External body 24 : Face 15, 22: Heat dissipation materials 31 : Gap X: Stacking axis direction

Claims

Claim 1 A solid-state battery in which a heat dissipation material is accommodated between an electrode body and an outer body, wherein, under an environment of 25°C, a current value of 0.5 C is set, and a cycle is performed by charging from a charge rate of 0% to 100% and discharging from a charge rate of 100% to 0% as one cycle, and the cycle is repeated 200 times, and the heat dissipation material is in contact with both the electrode body and the outer body when the charge rate is discharged to 0% after being charged to 100%. Claim 2 In claim 1, the heat dissipation material is a solid-state battery comprising a resin or an elastomer. Claim 3 In claim 2, the resin comprises at least one type selected from silicone resin and acrylic resin, forming a solid-state battery. Claim 4 A solid-state battery according to claim 1, wherein the heat dissipation material comprises a filler, and the filler comprises at least one type selected from ceramic filler and metal filler. Claim 5 In claim 1, the heat dissipation material is a solid battery in which the value of the compressive permanent deformation is smaller than the value of the compressive permanent deformation of a reference heat dissipation material satisfying the following condition 1. Condition 1: The reference heat dissipation material is in contact with both the electrode body and the outer body when an unused solid battery in which the reference heat dissipation material is contained between the electrode body and the outer body is charged to a charge rate of 100% and then discharged to a charge rate of 0%. Claim 6 In claim 1, the heat dissipation material is a solid-state battery having a thermal conductivity of less than 11.5 W / m·K and a compression permanent deformation of less than 98.8%. Claim 7 In claim 1, the heat dissipation material is a solid-state battery having electrical insulation properties. Claim 8 In claim 1, a solid-state battery that is a rectangular battery. Claim 9 In claim 1, the outer body has a rectangular shape, and the surface in contact with the heat dissipation material forms a convex shape toward the interior of the solid battery. Claim 10 In claim 1, a solid-state battery that is an all-solid-state battery. Claim 11 A method for manufacturing a solid-state battery in which an electrode body and a heat dissipation material are housed in an outer body, comprising: a process of housing the electrode body and the heat dissipation material in the outer body such that the heat dissipation material contacts both sides of the electrode body and the outer body; and a process of compressing the heat dissipation material by press-fitting the electrode body in the direction of the stacking axis of the electrode body and the heat dissipation material, wherein the heat dissipation material comprises a material satisfying the following condition 2. Condition 2: In a solid-state battery in which the material is housed between the electrode body and the outer body, under an environment of 25°C, the current value is set to 0.5 C, and a cycle test is performed in which charging from a charge rate of 0% to 100% and discharging from a charge rate of 100% to 0% constitutes one cycle, and the said cycle is repeated 200 times; and when the electrode body and the outer body are discharged to a charge rate of 0% after charging to a charge rate of 100%. It is in contact with Western medicine. Claim 12 In claim 11, a method for manufacturing a solid-state battery having a process of additionally encapsulating the electrode body and the heat dissipation material in the outer body while the heat dissipation material is compressed. Claim 13 A method for manufacturing a solid-state battery according to claim 11, additionally comprising a process of deforming the surface of the outer body in contact with the heat dissipation material by pressing the outer body toward the heat dissipation material. Claim 14 In claim 11, a method for manufacturing a solid-state battery having, additionally, a process of injecting the heat dissipation material into the gap between the electrode body and the outer body.

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