All-solid battery system

Abstract

To provide an energy saving all-solid battery system capable of maintaining bearing which is applied to an all-solid battery with little energy.SOLUTION: An all-solid battery system comprises: an all-solid battery configured by laminating a plurality of electric cells; a pressing device which applies predetermined bearing to the all-solid battery in a lamination direction; and a control device which operates the pressing device. The pressing device includes a compression device and a maintenance device. Actuation efficiency of a compressing operation of the compression device is higher than that of the maintenance device, and power consumption of the maintenance device during compressing operation stop is less than that of the compression device. The control device makes a load sharing rate of the maintenance device during charging and charging / discharging stop higher than that of the compression device, thereby providing an energy saving all-solid battery system capable of continuously applying predetermined bearing to the all-solid battery.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an all-solid-state battery system, and more particularly to an all-solid-state battery system that maintains surface pressure applied to an all-solid-state battery. [Background technology]

[0002] In all-solid-state batteries using a solid electrolyte, electrolyte particles have difficulty entering the gaps between active material particles, which tends to reduce the contact area between the electrolyte and the active material and lower the ion conduction efficiency. Therefore, it is necessary to apply pressure to minimize the gaps that form between the active material particles and the solid electrolyte particles.

[0003] Furthermore, the active material absorbs and releases ions during charging and discharging, which causes the all-solid-state battery to expand and contract, so it is necessary to adjust the surface pressure applied to the all-solid-state battery.

[0004] Patent Document 1 discloses a battery system in which pressure on the battery is maintained by applying power to a soft actuator provided at an end of the battery in the stacking direction to change the volume of the soft actuator. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2021-051862 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the device described in Patent Document 1, even when the volume of the battery is not expanded, such as during charging, it is necessary to continue applying power to maintain the volume of the soft actuator.

[0007] The present invention has been made in view of the problems associated with the conventional art, and an object of the present invention is to provide an energy-saving all-solid-state battery system that can maintain the surface pressure applied to the all-solid-state battery with less energy. [Means for solving the problem]

[0008] As a result of extensive research into achieving the above object, the present inventors have found that the above object can be achieved by compressing the all-solid-state battery mainly with a compression device having high operating efficiency to maintain the surface pressure when the all-solid-state battery contracts, and by maintaining the surface pressure applied to the all-solid-state battery mainly with a device consuming less energy when the all-solid-state battery expands or its volume remains constant, thereby completing the present invention.

[0009] That is, the all-solid-state battery system of the present invention includes an all-solid-state battery formed by stacking a plurality of unit cells, a pressing device that applies a predetermined surface pressure to the all-solid-state battery in the stacking direction, and a control device that operates the pressing device. The pressing device has a compression device and a maintenance device, The compression device has a higher operating efficiency in compression operation than the maintenance device, and the maintenance device consumes less energy than the compression device when the compression operation is stopped, The control device is characterized in that the load sharing rate of the maintenance device is higher than that of the compression device during charging and when charging / discharging is stopped. [Effects of the Invention]

[0010] According to the present invention, when the volume of the all-solid-state battery expands and when the volume is constant, the surface pressure applied to the all-solid-state battery is maintained mainly by a device that consumes less energy, and therefore it is possible to provide an energy-saving all-solid-state battery system that can continuously apply a predetermined surface pressure to the all-solid-state battery. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic diagram of an all-solid-state battery system including a pressing device in which a compression device and a maintenance device are arranged in parallel. [Figure 2] FIG. 1 is a schematic diagram of an all-solid-state battery system including a pressing device that integrates a compression device and a maintenance device. DETAILED DESCRIPTION OF THE INVENTION

[0012] The all-solid-state battery system of the present invention will be described in detail. The all-solid-state battery system of the present invention includes an all-solid-state battery formed by stacking a plurality of unit cells and a pressing device, which are housed in a housing, and further includes a control device that operates the pressing device.

[0013] The pressing device is disposed at an end of the all-solid-state battery in the stacking direction, and moves forward and backward in response to the expansion and contraction of the all-solid-state battery, pressing the all-solid-state battery to apply a predetermined surface pressure.

[0014] The pressing device of the present invention includes a compression device and a maintenance device, and the compression device has a higher operating efficiency of the compression operation than the maintenance device, and the maintenance device consumes less energy than the compression device to maintain the surface pressure when the compression operation is stopped, i.e., when the all-solid-state battery is expanding other than when it is contracting and when the volume is constant.

[0015] The compression device compresses the all-solid-state battery in response to volumetric contraction that accompanies discharge of the all-solid-state battery, and can use, for example, an actuator having a screw, a motor that rotates the screw, and a rod that is threadedly engaged with the screw. This actuator maintains surface pressure by rotating the screw with the motor to move the rod that is threadedly engaged with the screw back and forth, thereby pressing the all-solid-state battery.

[0016] By increasing the reduction ratio of the reducer that transmits the rotational force of the motor to the screw, such an actuator can press the solid-state battery with a small operating torque, reducing the energy consumed when compressing the solid-state battery. Not only is this actuator highly efficient, it can also be miniaturized because it can be operated with an electric motor with a small output.

[0017] Preferably, the screw is a ball screw. When the screw is a ball screw, the frictional force between the female screw formed on the rod and the screw shaft on which the male screw is formed is significantly reduced compared to a trapezoidal screw, so that the all-solid-state battery can be compressed with high efficiency, and when the all-solid-state battery expands, the rod can be pushed back by the all-solid-state battery simply by stopping operation, and the rod can be retracted without consuming energy.

[0018] The motor for the actuator may be an electric motor or a hydraulic motor.

[0019] Furthermore, the maintaining device maintains the surface pressure applied to the all-solid-state battery against the reaction force from the all-solid-state battery when the volume of the all-solid-state battery expands due to charging or when the volume is constant when charging / discharging is stopped.

[0020] As the maintaining device, for example, an actuator equipped with a reducer having a smaller reduction ratio than the actuator of the compressing device, or a hydraulic device can be used.

[0021] The hydraulic device has a cylinder, a piston housed in the cylinder, a valve that adjusts the flow of hydraulic oil in and out of a hydraulic chamber formed by the cylinder and the piston, and a rod connected to the piston, and, if necessary, a pump that pressure-feeds hydraulic oil into the hydraulic chamber.

[0022] The hydraulic device can withstand the reaction force from the all-solid-state battery simply by closing the valve to stop the hydraulic oil from flowing out of the cylinder, and can be used preferably because it does not consume energy to maintain the surface pressure.

[0023] Furthermore, the hydraulic device does not necessarily have to have compression capacity, and by eliminating compression capacity, not only is a pump that pressurizes hydraulic oil into the hydraulic chamber unnecessary, but there is also no need to increase the area of ​​the piston to increase compression capacity, making it possible to make it smaller, and it can be used particularly preferably.

[0024] The pressing device may be formed by arranging a compression device and a maintenance device in parallel as shown in FIG. 1, and combining separate independent compression devices and maintenance devices, but it can be made smaller if the compression device and maintenance device are integrated as shown in FIG. 2.

[0025] In the integrated pressing device, a piston housed in a cylinder is threadedly engaged with a screw inserted into the cylinder, connecting the piston to a rod.

[0026] In this pressing device, the piston moves when a screw is rotated by a motor while a valve that regulates the flow of hydraulic oil in and out of the hydraulic chamber is open, and the rod moves back and forth as hydraulic oil flows in and out of the hydraulic chamber. Then, by closing the valve, the movement of the piston and rod is restricted, and the surface pressure can be maintained.

[0027] The control device operates the pressing device based on a volume change amount due to charging and discharging of the all-solid-state battery. The volume change amount may be detected from a current flowing due to charging and discharging, or may be detected from a pressure sensor to detect a surface pressure applied to the all-solid-state battery.

[0028] Specifically, during discharge, i.e., during volume contraction of the all-solid-state battery, the compression device is operated so that its load sharing rate is higher than that of the maintenance device, and when there is no volume change during volume expansion due to charging or when charging / discharging is stopped, the maintenance device is operated so that its load sharing rate is higher than that of the compression device.

[0029] Furthermore, when the volume of the all-solid-state battery contracts, the load is shared only by the compression device, and when the volume of the all-solid-state battery expands or there is no volume change, the load is shared only by the maintenance device.

[0030] Specifically, when the volume of the all-solid-state battery contracts, the compression device presses the all-solid-state battery to maintain the surface pressure, and the valve of the maintenance device is opened to allow hydraulic oil to flow into the cylinder, causing the maintenance device to follow the compression device.

[0031] Then, when the volumetric contraction of the all-solid-state battery stops, the valve of the maintaining device is closed to maintain the surface pressure, and the pressing by the compressing device is stopped.

[0032] Thereafter, when the volume of the all-solid-state battery begins to expand due to charging, the valve of the hydraulic device is slightly opened to prevent the surface pressure of the all-solid-state battery from becoming too high, and the rod of the maintaining device is retracted to follow the volume expansion of the all-solid-state battery, thereby maintaining the surface pressure of the all-solid-state battery.

[0033] As a result, the all-solid-state battery can be compressed with high efficiency during discharge to maintain the surface pressure with little energy, and the surface pressure of the all-solid-state battery can be maintained against the reaction force from the all-solid-state battery with little energy during charging and when charging and discharging are stopped, so it is possible to maintain a state in which a predetermined surface pressure is applied to the all-solid-state battery with little energy.

[0034] The all-solid-state battery system of the present invention preferably has an elastic member such as a spring arranged in series with the pressing device.

[0035] By providing a spring between the pressing device and the all-solid-state battery or at the end of the all-solid-state battery opposite to the pressing device side, and pressing the all-solid-state battery with the spring and pressing device, even if the advance / retract position of the rod of the pressing device shifts in response to a change in the volume of the all-solid-state battery, the spring absorbs the shift, making it possible to maintain the surface pressure applied to the all-solid-state battery.

[0036] Furthermore, when the amount of change in volume of the all-solid-state battery is small and within a predetermined range, such as when the supply of power from the all-solid-state battery to the outside is stopped for a long period of time and the all-solid-state battery gradually shrinks due to natural discharge, the control device can maintain the surface pressure of the all-solid-state battery even if it stops the operation of the compression device, and there is no need for the compression device to continue operating, thereby enabling energy conservation. [Explanation of symbols]

[0037] 1 All-solid-state battery 2 Pressing device 3 Compression device 31 Motor 32 screws 33 Rod 34 Reducer 4 Maintenance device 41 cylinders 42 Piston 43 Rod 44 Hydraulic oil 45 Hydraulic chamber 46 Reserve tank 5 Elastic body (spring) 6. Housing

Claims

1. an all-solid-state battery made up of multiple stacked single cells; a pressing device that applies a predetermined surface pressure to the all-solid-state battery in its stacking direction; a control device that operates the pressing device, The pressing device includes a compression device and a maintenance device, The compression device has a higher operational efficiency in compression operation than the maintenance device, The maintenance device consumes less energy than the compression device when the compression operation is stopped, The control device controls the load sharing rate of the maintaining device to be higher than that of the compressing device during charging and when charging and discharging are stopped.

2. the compression device is an actuator having a screw, a motor that rotates the screw, and a rod that advances and retreats due to the rotation of the screw, 2. The all-solid-state battery system according to claim 1, wherein the maintenance device is a hydraulic device having at least a cylinder, a piston housed in the cylinder, a valve that adjusts the flow of hydraulic oil into and out of a hydraulic chamber formed by the cylinder and the piston, and a rod connected to the piston.

3. The all-solid-state battery system according to claim 2 , wherein the maintaining device does not have a compressing capability.

4. The all-solid-state battery system according to claim 2 , further comprising an elastic member arranged in series with the pressing device.

5. 5. The all-solid-state battery system according to claim 4, wherein the control device stops operation of the compression device when a volume change amount of the all-solid-state battery is within a predetermined range.

6. The all-solid-state battery system according to claim 2 , wherein the pressing device has the compressing device and the maintaining device arranged in parallel.

7. 3. The all-solid-state battery system according to claim 2, wherein the pressing device is configured such that the piston housed in the cylinder is threadedly engaged with the screw inserted into the cylinder, the piston is connected to the rod, and the compression device and the maintaining device are integrated.

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