Battery system

Abstract

The battery system (100) comprises a single cell (10) made of a sulfide-based all-solid-state battery, a battery module (200) in which a plurality of single cells (10) are stacked between a pair of restraining members (31, 32), an intermediate plate (60) disposed between the stacked single cells (10), a detection unit configured to detect a load applied to the intermediate plate (60), and an estimation unit (300) configured to estimate the generation of hydrogen sulfide in the single cell (10) based on a change in the load applied to the intermediate plate (60).

Description

Technology Field

[0001] The present disclosure relates to a battery system. Background Technology

[0002] Japanese Patent Publication No. 2022-46077 discloses a battery system in which, in a secondary battery in which a sulfur-based material is used for at least one of the positive electrode and the solid electrolyte, the secondary battery is cooled by a cooler when the generation of hydrogen sulfide is predicted or detected.

[0003] In Japanese Patent Publication No. 2022-46077, the generation of hydrogen sulfide gas from a secondary battery is detected by detecting the pressure inside a battery case accommodating the secondary battery, or the hydrogen sulfide concentration (sulfur concentration) inside the battery case.

[0004] In the configuration of Japanese Patent Publication No. 2022-46077, hydrogen sulfide gas generated from a secondary battery cannot be detected until the hydrogen sulfide gas fills the battery case and the pressure inside the battery case rises, or until the hydrogen sulfide concentration inside the battery case increases.

[0005] The present disclosure enables the detection of hydrogen sulfide generation before hydrogen sulfide gas fills the battery case.

[0006] The battery system of the present disclosure comprises a single cell which is a sulfide-based all-solid-state battery, a battery module in which a plurality of single cells are stacked between a pair of restraining members, an intermediate plate disposed between the stacked single cells, a detection unit configured to detect a load applied to the intermediate plate, and an estimation unit configured to estimate the generation of hydrogen sulfide in the single cell based on a change in the load applied to the intermediate plate.

[0007] In this configuration, the single cell is composed of a sulfide-based all-solid-state battery. In the present disclosure, a sulfide-based all-solid-state battery is one in which at least one of the positive electrode material or the solid electrolyte material contains a sulfur component. The single cell is stacked between a pair of restraining members to form a battery module. An intermediate plate is disposed between the stacked single cells. A detection unit detects a load applied to the intermediate plate. When hydrogen sulfide gas is generated inside the single cell, the internal pressure of the single cell rises, and the volume of the single cell increases. As the volume of the single cell increases, the load applied to the intermediate plate changes. An estimation unit estimates the generation of hydrogen sulfide in the single cell based on the change in the load applied to the intermediate plate. Since the estimation unit estimates the generation of hydrogen sulfide in the single cell based on the change in the load applied to the intermediate plate, the battery system can detect the generation of hydrogen sulfide before the battery case is filled with hydrogen sulfide gas.

[0008] The intermediate plate may be fixed in a cantilevered state to the base member to which the restraining member is fixed. The detection part may be a deformation gauge provided on the intermediate plate.

[0009] In this configuration, the intermediate plate is fixed in a cantilevered state to a base member to which a restraining member is fixed. Therefore, when hydrogen sulfide gas is generated inside a single cell and the volume of the single cell increases, the load applied to the intermediate plate changes, causing the intermediate plate to bend with the fixed end as a support point. By detecting this bending by a strain gauge provided on the intermediate plate, the battery system can estimate the generation of hydrogen sulfide in the single cell.

[0010] The estimation unit may be configured to determine the direction of bending deformation detected by a strain gauge. The estimation unit may also be configured to specify the placement location of the single cell where hydrogen sulfide is being generated based on the relationship between the direction of bending deformation and the position of the intermediate plate in the stacking direction of the single cell.

[0011] The intermediate plate may be configured to displace in the stacking direction of the single cell. The detection part may be a sensor configured to detect the displacement of the intermediate plate.

[0012] In this configuration, the intermediate plate is displaceable in the stacking direction of the single cells. Therefore, when hydrogen sulfide gas is generated inside a single cell and the volume of the single cell increases, the load applied to the intermediate plate changes, causing the intermediate plate to displace (move) in the stacking direction. By detecting this displacement by a sensor, the battery system can estimate the generation of hydrogen sulfide in the single cell.

[0013] The estimation unit may be configured to determine the direction of displacement of the intermediate plate detected by the sensor. The estimation unit may also be configured to specify the placement location of the single cell where hydrogen sulfide is being generated based on the relationship between the direction of displacement of the intermediate plate and the position of the intermediate plate in the stacking direction of the single cells.

[0014] The single cell may be a laminated all-solid-state battery having a laminate film as an outer component.

[0015] In this configuration, the single cell is a laminated all-solid-state battery, and the outer casing is composed of a laminate film. The laminate film is flexible compared to the metal case that constitutes the prismatic battery. Therefore, when the internal pressure of the single cell increases, the volume of the single cell increases relatively easily. For this reason, the battery system can estimate the generation of hydrogen sulfide in the single cell with relatively high precision based on changes in the load applied to the intermediate plate.

[0016] The single cell may include a sulfide-based solid electrolyte.

[0017] According to this composition, it is possible to detect that hydrogen sulfide is generated when a sulfur component contained in a sulfide-based solid electrolyte reacts with moisture.

[0018] According to the present disclosure, the generation of hydrogen sulfide can be detected before the battery case is filled with hydrogen sulfide gas. Brief explanation of the drawing

[0019] The features, advantages, and technical and industrial significance of exemplary embodiments of the present invention are described below with reference to the accompanying drawings, in which similar reference numerals denote similar elements. FIG. 1 is a diagram schematically showing the overall configuration of a battery system according to the present embodiment. Figure 2a is a diagram illustrating the schematic configuration of a single cell. Figure 2b is a diagram illustrating the schematic configuration of a single cell. Figure 3a is a diagram illustrating a stacking method of single cells. Figure 3b is a diagram illustrating a stacking method of single cells. Figure 4 is a flowchart showing an example of hydrogen sulfide generation estimation processing executed in a control unit. Figure 5 is a diagram showing the schematic configuration of a battery module in a modified example. Specific details for implementing the invention

[0020] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In addition, the same or substantial parts in the drawings are denoted by the same reference numerals, and their descriptions are not repeated.

[0021] FIG. 1 is a schematic diagram showing the overall configuration of a battery system (100) according to an embodiment of the present disclosure. The battery system (100) includes a battery module (200) and a control device (300). The battery module (200) is a battery that connects a plurality of single cells (10). The plurality of single cells (10) are stacked between a pair of end plates (31, 32).

[0022] FIGS. 2a and 2b are drawings illustrating the schematic configuration of a single cell (10) in the present embodiment. FIG. 2a is viewed from the top surface of the single cell (10). The single cell (10) is a laminated all-solid-state battery using a laminate film as an outer casing member (20). A negative terminal (negative tab) (1a) and a positive terminal (positive tab) (5a) protrude from the outer casing member (20). The laminate film may be, for example, a pouch made of aluminum laminate film, or a film with a three-layer structure in which an aluminum foil is sandwiched between resin films.

[0023] FIG. 2b shows an all-solid-state battery stack (15) housed in an outer member (20), and shows the IIB-IIB cross-section of FIG. 2a. The all-solid-state battery stack (15) has, for example, three all-solid-state battery elements (8) in which a negative electrode current collector layer (1), a negative electrode active material layer (2), a solid electrolyte layer (3), a positive electrode active material layer (4), and a positive electrode current collector layer (5) are stacked in this order. The three all-solid-state battery elements (8) are stacked. Adjacent all-solid-state battery elements (8) share the negative electrode current collector layer (1) or the positive electrode current collector layer (5). For adjacent all-solid-state battery elements (8), the stacking order of the respective negative electrode current collector layer (1), negative electrode active material layer (2), solid electrolyte layer (3), positive electrode active material layer (4), and positive electrode current collector layer (5) is reversed. The negative electrode current collector layer (1) is connected to the negative electrode terminal (1a). The positive electrode current collector layer (5) is connected to the positive electrode terminal (5a). Additionally, the number of all-solid-state battery elements (8) included in the all-solid-state battery laminate (15) may be one or four or more. The insulating film (7) insulates the all-solid-state battery laminate (15) and the outer member (laminate film) (20).

[0024] The single cell (10) is a sulfide-based all-solid-state battery. In the present disclosure, a sulfide-based all-solid-state battery is one in which at least one of the materials of the positive electrode active material layer (4) or the solid electrolyte layer (3) contains a sulfur component. In the present embodiment, the solid electrolyte layer (3) includes a sulfide-based solid electrolyte. For example, the sulfide-based solid electrolyte may be made from phosphorus pentasulfide (P2S5) or lithium sulfide (Li2S) as starting materials. In this case, the positive electrode active material layer (4) may include, for example, lithium cobaltate, lithium nickelate, lithium iron phosphate, etc. When the solid electrolyte layer (3) is composed of an oxide-based solid electrolyte, the positive electrode active material layer (4) uses a sulfur-based positive electrode active material. As the sulfur-based positive electrode active material, it may be an organic sulfur compound or an inorganic sulfur compound. In addition, both the solid electrolyte layer (3) and the positive electrode active material layer (4) may contain a sulfur component.

[0025] Referring to FIG. 1, a plurality of single cells (10) are stacked by being placed between a pair of end plates (31, 32). FIGS. 3a and 3b are drawings illustrating a method of stacking single cells (10). The single cells (10) are flat in shape, and as shown in FIG. 3a, the single cells (10) may be stacked with each other such that the outer casing member (20) of the single cells (10) comes into contact. Additionally, a flat spacer (not shown) may be interposed between the single cells (10) to stack the plurality of single cells (10). Furthermore, as shown in FIG. 3b, a pair of frame pairs (81, 82) having inner surfaces corresponding to the outer shape of the single cells (10) may be used to cover the single cells (10), and the single cells (10) covered by the pair of frame pairs (81, 82) may be stacked.

[0026] Returning to FIG. 1, an intermediate plate (60) is disposed between the single cells (10) and the single cells (10) in the central part of the stacking direction of the single cells (10). The plurality of single cells (10) and the intermediate plate (60) are sandwiched between a pair of end plates (31, 32) in a stacked state. A predetermined restraining load is applied to the plurality of single cells (10), the intermediate plate (60), and the pair of end plates (31, 32), for example by a restraining band (80). The pair of end plates (31, 32) are fixed to the base plate (50) by brackets (41, 42). Additionally, the pair of end plates (31, 32) is an example of a "pair of restraining members" of the present disclosure.

[0027] In this embodiment, the intermediate plate (60) is inserted into the groove (51) formed in the bottom plate (50) and fixed. As a result, the intermediate plate (60) is fixed to the bottom plate (50) in a cantilevered state.

[0028] A strain gauge (70) is provided on the intermediate plate (60). The strain gauge (70) may be a thin strain gauge or a semiconductor strain gauge. The strain gauge (70) detects bending deformation of the intermediate plate (60).

[0029] The battery module (200) includes a single cell (10), an intermediate plate (60), a bottom plate (50), etc., stacked between a pair of end plates (31, 32). The battery module (200) is fixed to a battery case (90). The battery case (90) is a housing that accommodates the battery module (200).

[0030] The control device (300) is composed of a processor such as a Central Processing Unit (CPU), memory such as Read Only Memory (ROM) and Random Access Memory (RAM), input / output ports, etc., and controls the charging and discharging of the battery module (200). In this embodiment, the control device (300) estimates the generation of hydrogen sulfide (H2S) in the single cell (10) based on the detection signal of the strain gauge (70). The control device (300) functions as the “estimation unit” of the present disclosure.

[0031] FIG. 4 is a flowchart illustrating an example of a hydrogen sulfide generation estimation process executed in a control device (300). This flowchart is repeated at predetermined intervals. First, in step 10 (hereinafter, the step is abbreviated as “S”), a change in load L applied to the intermediate plate (60) ΔL is obtained based on the detection signal of the strain gauge (70).

[0032] In any single cell (10) of the battery module (200), if hydrogen sulfide is generated when a sulfur component contained in the solid electrolyte layer (3) or the positive electrode active material layer (4) reacts with water for some reason, the volume of the single cell (10) increases due to gas pressure. When the volume of the single cell (10) increases, the load applied to the intermediate plate (60) changes. In FIG. 1, if hydrogen sulfide is generated in the single cell (10) to the left of the intermediate plate (60), a force Fa in the direction indicated by the solid arrow acts on the intermediate plate (60). In FIG. 1, if hydrogen sulfide is generated in the single cell (10) to the right of the intermediate plate (60), a force Fb in the direction indicated by the dashed arrow acts on the intermediate plate (60).

[0033] When force Fa or force Fb is applied to the intermediate plate (60), a bending moment is applied to the intermediate plate (60), and a bending deformation is detected by the deformation gauge (70). In S10, the magnitude of this bending deformation is obtained as the amount of change in load ΔL applied to the intermediate plate (60).

[0034] In the subsequent S11, it is determined whether the load change amount ΔL is greater than or equal to a predetermined value A. If the load change amount ΔL is less than the predetermined value A, a negative determination is made (S11: "No"), and the current routine is terminated. If the load change amount ΔL is greater than or equal to the predetermined value A, a positive determination is made (S11: "Yes"), and the process proceeds to S12. Additionally, the predetermined value A is set in advance through experiments, etc.

[0035] In S12, it is determined that hydrogen sulfide is being generated in the single cell (10), and the current routine is terminated. Additionally, in S12, it is possible to determine whether the bending deformation detected by the strain gauge (70) is in the compression direction or the tension direction, thereby specifying the location of the single cell (10) where hydrogen sulfide is being generated. For example, as shown in FIG. 1, when a strain gauge (70) is provided on the left side of the intermediate plate (60), when a force Fa is applied to the intermediate plate (60), the strain gauge (70) outputs a detection signal in the tension direction (elongation direction), and when a force Fb is applied to the intermediate plate (60), the strain gauge (70) outputs a detection signal in the compression direction (contraction direction). Therefore, when the detection signal of the strain gauge (70) is in the tension direction, it can be determined that hydrogen sulfide is being generated in either of the single cells (10) to the left of the intermediate plate (60). When the detection signal of the strain gauge (70) is in the compression direction, it can be determined that hydrogen sulfide is being generated in either of the single cells (10) to the right of the intermediate plate (60).

[0036] According to the present embodiment, a change in the load applied to the intermediate plate (60) is detected by a bending deformation detected by a deformation gauge (70) provided on an intermediate plate (60) placed between stacked single cells (10). Then, based on the change in the load applied to the intermediate plate (60), the generation of hydrogen sulfide in the single cell (10) is estimated, so that hydrogen sulfide is detected in the single cell (10) before hydrogen sulfide fills the battery case (90).

[0037] In this embodiment, a pair of end plates (31, 32) and an intermediate plate (60) were fixed to the bottom plate (50). However, a pair of end plates (31, 32) and an intermediate plate (60) may be directly fixed to the battery case (90).

[0038] Variant example

[0039] FIG. 5 is a diagram showing the schematic configuration of a battery module (200a) in a modified example. In the battery module (200a), the intermediate plate (61) located in the center of the stacked single cell (10) is not fixed to the bottom plate (55). Because of this, the intermediate plate (61) can be displaced (moved) in the stacking direction of the single cell (10). A displacement sensor (displacement meter) (71) is provided on the bottom plate (55) in a portion facing the intermediate plate (61). The displacement sensor (71) may be a variable resistance type displacement sensor in which resistance changes according to the displacement of the intermediate plate (61), or a non-contact linear displacement sensor using the Hall effect.

[0040] In the modified example, the generation of hydrogen sulfide in the single cell (10) is estimated by the processing shown in the flowchart of FIG. 4. In the modified example, in S10, the amount of change in load L applied to the intermediate plate (61) (amount of load change) ΔL is obtained based on the detection signal of the displacement sensor (71).

[0041] In any single cell (10) of the battery module (200), if hydrogen sulfide is generated when a sulfur component contained in the solid electrolyte layer (3) or the positive electrode active material layer (4) reacts with water for some reason, the volume of the single cell (10) increases due to gas pressure. When the volume of the single cell (10) increases, the load applied to the intermediate plate (61) changes. In FIG. 5, if hydrogen sulfide is generated in the single cell (10) to the left of the intermediate plate (61), a force Fa in the direction indicated by the solid arrow acts on the intermediate plate (61). In FIG. 5, if hydrogen sulfide is generated in the single cell (10) to the right of the intermediate plate (61), a force Fb in the direction indicated by the dashed arrow acts on the intermediate plate (61).

[0042] When a force Fa or a force Fb is applied to the intermediate plate (61), the intermediate plate (61) is displaced in the stacking direction of the single cell (10), so the displacement of the intermediate plate (61) is detected by the displacement sensor (71). In S10, the magnitude of this displacement is obtained as the amount of change in load ΔL applied to the intermediate plate (61). The processing of S11 and S12 is the same as in the above embodiment.

[0043] In S12, it is also possible to determine the location of the single cell (10) where hydrogen sulfide is being generated by the direction of displacement detected by the displacement sensor (71). For example, when a force Fa is applied to the intermediate plate (61) and the intermediate plate (61) is displaced to the right in FIG. 5, it can be determined that hydrogen sulfide is being generated in any of the single cells (10) to the left of the intermediate plate (61). Additionally, when a force Fb is applied to the intermediate plate (61) and the intermediate plate (61) is displaced to the left in FIG. 5, it can be determined that hydrogen sulfide is being generated in any of the single cells (10) to the right of the intermediate plate (61).

[0044] In this variant as well, a change in the load applied to the intermediate plate (61) is detected by the displacement detected by a displacement sensor (71) that detects the displacement of the intermediate plate (61) placed between the stacked single cells (10). Then, based on the change in the load applied to the intermediate plate (61), the generation of hydrogen sulfide in the single cell (10) is estimated, so that hydrogen sulfide is generated in the single cell (10) before the battery case (90) is filled with hydrogen sulfide.

[0045] In the above embodiments and variations, an intermediate plate (60) equipped with a strain gauge (70), or a combination of an intermediate plate (61) and a displacement sensor (71), was provided in the central part of the stacking direction of the single cell (10). However, these locations are not limited to the central part. A plurality of intermediate plates (60) may be arranged, for example, at equal intervals in the stacking direction of the single cell (10). Alternatively, a combination of an intermediate plate (61) and a displacement sensor (71) may be arranged in multiple equal intervals in the stacking direction of the single cell (10). Furthermore, both the intermediate plate (60) equipped with the strain gauge (70) and the combination of an intermediate plate (61) and a displacement sensor (71) may be provided at intervals on a single cell module.

[0046] Additionally, the battery system (100) may be mounted on an electric vehicle or may be for stationary use.

[0047] The embodiments disclosed herein should be considered illustrative in all respects and not restrictive. The scope of the disclosure is defined by the claims, not by the description of the embodiments described above, and is intended to include all modifications within the meaning and scope equivalent to the claims.

Claims

Claim 1 A battery system (100) comprising: a single cell (10) which is a sulfide-based all-solid-state battery; a battery module (200; 200a) in which a plurality of the single cells (10) are stacked between a pair of restraining members (31, 32); an intermediate plate (60; 61) disposed between the stacked single cells (10); a detection unit configured to detect a load applied to the intermediate plate (60; 61); and an estimation unit (300) configured to estimate the generation of hydrogen sulfide in the single cell (10) based on a change in the load applied to the intermediate plate (60; 61). Claim 2 In claim 1, the intermediate plate (60) is fixed in a cantilevered state to a base member (50) to which the restraining member (31, 32) is fixed, and the detection part is a deformation gauge (70) provided on the intermediate plate (60), in a battery system (100). Claim 3 In paragraph 2, the estimation unit (300) is configured to determine the direction of bending deformation detected by the deformation gauge (70), and to specify the placement location of the single cell (10) where hydrogen sulfide is being generated based on the relationship between the direction of the bending deformation and the position of the intermediate plate (60) in the stacking direction of the single cell (10). Claim 4 In claim 1, the intermediate plate (61) is configured to be displaced in the stacking direction of the single cell (10), and the detection unit is a sensor (71) that detects the displacement of the intermediate plate (61), in a battery system (100). Claim 5 In claim 4, the battery system (100) is configured such that the estimation unit (300) determines the direction of displacement of the intermediate plate (61) detected by the sensor (71), and specifies the placement location of the single cell (10) where hydrogen sulfide is being generated based on the relationship between the direction of displacement of the intermediate plate (61) and the position of the intermediate plate (61) in the stacking direction of the single cell (10). Claim 6 In any one of claims 1 to 5, the battery system (100) is a laminated all-solid-state battery having a laminate film as an outer member (20). Claim 7 In claim 6, the above single cell (10) is a battery system (100) comprising a sulfide-based solid electrolyte.

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