All-solid-state battery unit

Abstract

To provide an all-solid-state battery unit capable of improving energy efficiency by stabilizing charging and discharging characteristics in response to fluctuations in temperature and charging rates of an all-solid-state battery module.SOLUTION: An all-solid-state battery unit includes: a battery module in which a plurality of all-solid-state battery cells are stacked; pressurizing means for pressurizing the battery module; and control means for controlling the pressurizing means. The control means controls pressurizing force of the pressurizing means according to at least one of temperature of the battery module and a charging rate of the battery module.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an all-solid-state battery unit having an all-solid-state battery module in which a plurality of all-solid-state battery cells are stacked. [Background technology]

[0002] Vehicles such as EVs (Electric Vehicles) and HEVs (Hybrid Electrical Vehicles) are equipped with a power storage device that supplies power to a motor, etc. The power storage device is generally provided with a plurality of secondary batteries.

[0003] Lithium-ion batteries (LIBs) have traditionally been widely used as secondary batteries in EVs and HEVs, but lithium-ion batteries have the potential for overheating and fire due to the properties of their electrolyte. For this reason, attention is being paid to all-solid-state batteries, which offer characteristics such as higher safety, a wider usable temperature range, and shorter charging times compared to conventional lithium-ion batteries.

[0004] A typical method for manufacturing an all-solid-state battery is to integrate a positive electrode laminate including a positive electrode solid electrolyte and a positive electrode mixture with a negative electrode laminate including a negative electrode solid electrolyte and a negative electrode mixture by pressure bonding. By using a solid electrolyte, such an all-solid-state battery has a low possibility of overheating or ignition, and is therefore highly safe.

[0005] However, in order to maintain appropriate output characteristics and charging characteristics of all-solid-state batteries, it is important to maintain a state in which the positive electrode laminate and the negative electrode laminate are bonded together with a surface pressure within an appropriate range. For example, Patent Document 1 discloses a battery module configured to apply a restraint load to a laminate in which a plurality of unit cells are stacked using an elastic body. Furthermore, Patent Document 2 discloses a battery module configured to adjust the restraint load to a laminate in which a plurality of unit cells are stacked using a pressure adjustment member. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2019-128979 [Patent Document 2] Japanese Patent Application Publication No. 2019-128980 Summary of the Invention [Problem to be solved by the invention]

[0007] However, the battery modules disclosed in Patent Documents 1 and 2 maintain a restraining force in response to the expansion and contraction of the stack of unit cells. Because the charge and discharge characteristics of all-solid-state batteries change depending on the temperature, state of charge (SOC), and the like, there is a demand for all-solid-state batteries that can stabilize the charge and discharge characteristics in response to such fluctuations in temperature and state of charge, thereby improving energy efficiency.

[0008] The present invention has been proposed in view of the above-mentioned problems, and aims to provide an all-solid-state battery unit that can stabilize charge / discharge characteristics and improve energy efficiency in response to fluctuations in the temperature and charging rate of an all-solid-state battery module. [Means for solving the problem]

[0009] The all-solid-state battery unit of the present invention is a battery unit in which a plurality of all-solid-state battery cells are stacked. No. 1 A battery module; a second battery module in which the same number of all-solid-state battery cells as the first battery module are stacked; , a partition wall provided between the first battery module and the second battery module; a plurality of hydraulic cylinders respectively arranged at one end side of the first battery module in the stacking direction and at the other end side of the second battery module in the stacking direction; a hydraulic device that supplies hydraulic pressure commonly to the plurality of hydraulic cylinders; and a hydraulic device that controls the hydraulic device so that pressure is applied in directions in which the plurality of hydraulic cylinders face each other. The control means includes: a battery module including at least the first battery module and the second battery module; Temperature or Is full According to at least one of the values ​​of the dielectric constants, Hydraulic Device of The hydraulic pressure The control is characterized by:

[0010] According to the present invention, the internal resistance of the all-solid-state battery cell is controlled so that the charge characteristics during charging and the discharge characteristics during discharging are maximized according to the temperature and state of charge (SOC) of the all-solid-state battery module, thereby realizing an all-solid-state battery unit with always stable charge and discharge characteristics even when the temperature and state of charge change.

[0011] In the present invention, the control means controls the temperature of the battery module in response to a decrease in the temperature of the battery module. hydraulic pressure of means The hydraulic pressure Control may be performed to reduce the

[0012] In the present invention, the control means controls the charging rate of the battery module in response to a decrease in the charging rate of the battery module. hydraulic pressure of means The hydraulic pressure Alternatively, control may be performed to increase the

[0013] In addition, in the present invention, the control means , the above Pressure sensor that detects fluid pressure Sa The configuration may include: [Effects of the Invention]

[0014] According to the present invention, it is possible to provide an all-solid-state battery unit that can stabilize charge / discharge characteristics and improve energy efficiency in response to fluctuations in the temperature and charging rate of an all-solid-state battery module. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a schematic cross-sectional view showing an all-solid-state battery unit according to an embodiment of the present invention. [Figure 2] 1 is a graph showing the relationship between the thickness of an all-solid-state battery cell and the state of charge (SOC). [Figure 3] 1 is a graph showing the relationship between the internal resistance and the state of charge (SOC) of an all-solid-state battery cell. [Figure 4] 1 is a graph showing the relationship between the internal resistance and temperature of an all-solid-state battery cell. [Figure 5]1 is a graph showing the relationship between the internal resistance of an all-solid-state battery cell and the surface pressure (load applied to the all-solid-state battery cell). DETAILED DESCRIPTION OF THE INVENTION

[0016] An all-solid-state battery unit according to one embodiment of the present invention will be described below with reference to the drawings. Note that the embodiment described below is specifically described to provide a better understanding of the gist of the invention, and does not limit the present invention unless otherwise specified. Furthermore, the drawings used in the following description may show essential parts enlarged for convenience in order to make the features of the present invention easier to understand, and the dimensional ratios of each component may not necessarily be the same as those in reality.

[0017] An example of the configuration of an all-solid-state battery unit according to one embodiment of the present invention will be described. FIG. 1 is a schematic cross-sectional view showing an all-solid-state battery unit according to one embodiment of the present invention. The all-solid-state battery unit 10 of this embodiment includes an all-solid-state battery module 12 in which a plurality of all-solid-state battery cells 11, 11 . . . are stacked, a pressurizing means 13, and a control means 14.

[0018] The all-solid-state battery cell 11 may have the same configuration as a known all-solid-state battery cell, and may be formed by pressurizing and bonding a positive electrode laminate formed by pressurizing and bonding a positive electrode mixture layer and a positive electrode solid electrolyte layer of a positive electrode layer, and a negative electrode laminate formed by pressurizing and bonding a negative electrode mixture layer and a negative electrode solid electrolyte layer of a negative electrode layer.

[0019] The all-solid-state battery module 12 is composed of a plurality of stacked all-solid-state battery cells 11 described above, and in this embodiment, is composed of a first all-solid-state battery module 12A formed on one side of a central partition wall 41 and a second all-solid-state battery module 12B formed on the other side.

[0020] The first all-solid-state battery module 12A and the second all-solid-state battery module 12B are each formed by stacking the same number of all-solid-state battery cells 11, 11... symmetrically. The plurality of all-solid-state battery cells 11, 11... are electrically connected in parallel to each other. The all-solid-state battery module 12 may be housed in, for example, a heat-conductive housing (not shown).

[0021] The pressurizing means 13 includes a hydraulic cylinder 21 formed so as to contact the all-solid-state battery cells 11a arranged on one end side and the other end side in the stacking direction, a hydraulic device 22 that pressurizes and depressurizes hydraulic oil, which is an example of a pressurizing / depressurizing medium, and a pressure-resistant pipe 23 that connects the hydraulic device 22 and the hydraulic cylinder 21 and circulates the hydraulic oil. The hydraulic device 22 includes a pressurizing unit 22a, an accumulator (pressure storage device) 22b, and a pressure sensor 22c. The pressurizing / depressurizing medium used in the hydraulic device 22 is not limited to hydraulic oil as long as it is a liquid, and any liquid that undergoes little volume change due to pressurization / depressurization can be used.

[0022] The hydraulic cylinder 21 can apply pressure to the all-solid-state battery cells 11, 11 . . . that make up the all-solid-state battery module 12 along the stacking direction by using hydraulic oil pressurized by the hydraulic device 22.

[0023] The internal resistance of the all-solid-state battery cells 11, 11... changes depending on the load (surface pressure) applied from the hydraulic cylinder 21. More specifically, the greater the load (surface pressure) applied to the all-solid-state battery cells 11, 11..., the lower the internal resistance of each all-solid-state battery cell 11. Conversely, the greater the load (surface pressure) applied to the all-solid-state battery cells 11, 11..., the higher the internal resistance of each all-solid-state battery cell 11. When the internal resistance of the all-solid-state battery cell 11 increases, the temperature of the all-solid-state battery cell 11 increases due to the charge / discharge current.

[0024] The hydraulic device 22 constituting the pressurizing means 13 may be configured to collectively operate the hydraulic cylinders 21 formed in each of the plurality of all-solid-state battery modules 12, 12. Specifically, a pressure-resistant pipe 23 may be connected from one hydraulic device 22 to the hydraulic cylinders 21 formed in each of the plurality of all-solid-state battery modules 12, 12. With such a configuration, it is possible to apply a uniform load (surface pressure) to the plurality of all-solid-state battery modules 12, 12 with a low-cost configuration.

[0025] The control means 14 has, for example, a control circuit section 31 including an interface circuit or the like that controls the operation of the pressurizing unit 22a that constitutes the hydraulic device 22, a temperature sensor 32 that detects the temperature of the all-solid-state battery module 12 and outputs it to the control circuit section 31, and an SOC detection circuit 33 that detects the state of charge (SOC) of the all-solid-state battery module 12 and outputs it to the control circuit section 31.

[0026] The SOC detection circuit 33 may be, for example, an output voltage meter. The state of charge (SOC) can be calculated from the change in the output voltage of the all-solid-state battery module 12.

[0027] The temperature sensor 32 may be formed, for example, at a position in contact with the all-solid-state battery module 12. The temperature sensors 32 may be formed at a plurality of positions on the all-solid-state battery module 12 to enable detection of temperature distribution.

[0028] The control circuit section 31 controls the pressure of the hydraulic oil applied to the hydraulic cylinder 21 by the pressurizing unit 22a according to the temperature and state of charge (SOC) of the all-solid-state battery module 12 detected by the temperature sensor 32 and the SOC detection circuit 33.

[0029] The operation of the all-solid-state battery unit 10 of this embodiment configured as above will be described. The thickness of the all-solid-state battery cell 11 increases as the state of charge (SOC) increases (see the graph in FIG. 2). Furthermore, the internal resistance decreases as the state of charge (SOC) increases (see the graph in FIG. 3). Furthermore, when the internal resistance of the all-solid-state battery cell 11 increases, the temperature also increases due to the charge / discharge current (see the graph in FIG. 4). The relationship between the internal resistance of the all-solid-state battery cell 11 and the surface pressure (the load applied to the all-solid-state battery cell 11) is as shown in the graph in FIG. 5. Note that there is an appropriate usable range for the temperature and surface pressure of the all-solid-state battery cell 11, and upper and lower usage limits are set.

[0030] Based on this knowledge, the control means 14 controls the hydraulic device 22 so that the internal resistance is always optimized, thereby controlling the load applied to the all-solid-state battery cell 11, in order to suppress loss and heat generation both when charging and discharging the all-solid-state battery module 12.

[0031] Specifically, for example, an arbitrary threshold is set for temperature, and two states, temperature (low) and temperature (high), are set with this threshold as the boundary. Also, an arbitrary threshold is set for the state of charge (SOC), and two states, SOC (low) and SOC (high), are set with this threshold as the boundary.

[0032] Then, the control means 14 performs the control shown in Table 1 according to the temperature (two values) of the all-solid-state battery module 12 obtained by the temperature sensor 32 and the charging rate (two values) obtained by the SOC detection circuit 33. Note that the control shown in Table 1 below is an example of control and does not limit the specific control.

[0033] [Table 1]

[0034] By performing such control by operating the hydraulic device 22, it is possible to always maintain the internal resistance of the all-solid-state battery cell 11 at an optimum value according to the temperature and charging rate of the all-solid-state battery module 12. This makes it possible to always stabilize the charge / discharge characteristics in response to changes in the temperature and charging rate of the all-solid-state battery module 12.

[0035] As described above, according to the all-solid-state battery unit 10 of one embodiment of the present invention, the internal resistance of the all-solid-state battery cells 11 is controlled so as to maximize the charge characteristics during charging and the discharge characteristics during discharging, depending on the respective states of the temperature and state of charge (SOC) of the all-solid-state battery module 12. This makes it possible to realize an all-solid-state battery unit 10 whose charge and discharge characteristics are always stable even if the temperature and state of charge change.

[0036] In the above-described embodiment, both the temperature and the state of charge (SOC) of the all-solid-state battery module 12 are detected to control the load applied to the all-solid-state battery cell 11, but a configuration may also be adopted in which the load applied to the all-solid-state battery cell 11 is controlled based on only either the temperature or the state of charge (SOC) of the all-solid-state battery module 12, and the load is controlled so that the internal resistance is always minimized.

[0037] In addition, in the above-described embodiment, in order to simplify the configuration of the control circuit unit 31, both the temperature and the state of charge (SOC) of the all-solid-state battery module 12 are controlled at two values ​​with one set threshold as the boundary, but it is also possible to set multiple thresholds and control at multiple values, or to control at continuous values.

[0038] Although the embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, as well as within the scope of the invention and its equivalents as defined in the claims. [Industrial Applicability]

[0039] The all-solid-state battery unit of the present invention controls the internal resistance of the all-solid-state battery cells so that the charge characteristics during charging and the discharge characteristics during discharging are maximized according to the temperature and state of charge (SOC) of the all-solid-state battery module, thereby realizing an all-solid-state battery unit with consistently stable charge and discharge characteristics even when the temperature or state of charge changes. When used as a secondary battery for vehicles such as EVs and HEVs, such an all-solid-state battery unit can improve energy efficiency. Therefore, it has industrial applicability. [Explanation of symbols]

[0040] 10...All-solid-state battery unit 11...All-solid-state battery cell 12...All-solid-state battery module 13...Pressure means 14...Control means 21...Hydraulic cylinder 22...Hydraulic device 31...Control circuit section 32...Temperature sensor 33...SOC detection circuit

Claims

1. a first battery module in which a plurality of all-solid-state battery cells are stacked; a second battery module in which the same number of all-solid-state battery cells as the first battery module are stacked; a partition wall provided between the first battery module and the second battery module; a plurality of hydraulic cylinders respectively disposed at one end side of the first battery module in the stacking direction and at the other end side of the second battery module in the stacking direction; a single hydraulic device that supplies hydraulic pressure to the plurality of hydraulic cylinders in common; the control means controls the hydraulic device so that pressure is applied to the plurality of hydraulic cylinders in directions facing each other, the control means controls the hydraulic pressure of the hydraulic device in accordance with at least one of a temperature and a charging rate of battery modules including at least the first battery module and the second battery module.

2. 2. The all-solid-state battery unit according to claim 1, wherein the control means performs control to reduce the hydraulic pressure of the hydraulic pressure means in response to a decrease in temperature of the battery module.

3. 2. The all-solid-state battery unit according to claim 1, wherein the control means performs control to increase the hydraulic pressure of the hydraulic pressure means in response to a decrease in the charging rate of the battery module.

4. 4. The all-solid-state battery unit according to claim 1, wherein the control means includes a pressure sensor for detecting the liquid pressure.

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