System and method for controlling expansion and contraction of solid-state battery by using nitrogen isostatic pressing

Abstract

According to the system for controlling expansion and contraction of the solid-state battery by utilizing nitrogen isostatic pressing disclosed by the invention, air of an air compressor is separated by a gas separation membrane, and high-pressure dry high-purity nitrogen is generated and passes through a nitrogen inlet proportional servo control valve; the opening degree of the control valve is controlled through the pressure controller, high-purity nitrogen is accurately controlled to enter the space around the soft package battery cell elastically fixed in the sealed shell of the solid-state battery module, isostatic pressure can be accurately and uniformly applied in all directions, close contact between an electrode and electrolyte is maintained, gaps and stress concentration caused by volume expansion or shrinkage are reduced, and the service life of the solid-state battery module is prolonged. The MEMS hardware collects data in a sealed shell of the solid-state battery module in real time and sends the data to the pressure controller, and the method for controlling expansion and contraction of the solid-state soft package battery through closed-loop nitrogen gas isostatic pressing is formed by combining original characterization charging and discharging repeated expansion and contraction data of a battery cell of the solid-state battery. And expansion and contraction of the solid-state soft package battery in the charging and discharging process are controlled.

Description

Technical Field

[0001] The present invention belongs to the technical field of solid-state soft-pack batteries, and relates to a system for controlling the expansion and contraction of solid-state batteries by using isostatic pressure of nitrogen gas, and also relates to a method for controlling the expansion and contraction of solid-state batteries by using isostatic pressure of nitrogen gas. Background Art

[0002] Compared with existing liquid lithium-ion batteries, the most reasonable packaging form for solid-state batteries is an aluminum foil soft-pack sealed battery cell.

[0003] During the long-term use of solid-state batteries installed in vehicles (such as automobiles, airplanes, ships, energy storage, etc.), since both the electrolyte and the electrodes of the battery cell are of solid state properties, during the charge and discharge process of the solid-state soft-pack battery cell, due to the ion insertion and desorption mechanism between the electrolyte and the electrodes, repeated expansion and contraction will occur. With the accumulation of the number of charge and discharge cycles, microcracks will be generated at the solid-solid interface between the electrode and the electrolyte, the impedance of the solid-solid interface between the electrolyte and the electrode will increase, and ultimately the battery cell will fail and the battery will be damaged.

[0004] Therefore, it is necessary to control the pressure of the expansion and contraction of solid-state batteries. Several existing pressure loading methods include: Rigid fastening pressurization: It can only apply unidirectional contact pressurization, and stress concentration will occur at the pressurization application site, and the omnidirectional pressure is uneven, resulting in battery damage. Secondly, the rigid fastening pressurization design will make the internal fastening structure of the battery pack complex, and the number and structural weight of accessories will increase; Elastic fastening pressurization: It is only unidirectional elastic contact pressurization, with uniform local pressure but uneven omnidirectional pressure; Silicone oil immersion pressurization: It can apply omnidirectional pressurization, but the weight increases, the maintenance is complex, and the cost is relatively high. Summary of the Invention

[0005] The purpose of the present invention is to provide a system for controlling the expansion and contraction of solid-state batteries by using isostatic pressure of nitrogen gas, which can apply isostatic pressure to the solid-state battery omnidirectionally and uniformly.

[0006] Another purpose of the present invention is to provide a method for controlling the expansion and contraction of solid-state batteries by using isostatic pressure of nitrogen gas, which uses nitrogen gas to precisely apply omnidirectional nitrogen pressure constraint to the battery cells of the solid-state soft-pack battery module.

[0007] The technical solution adopted by the present invention is that a system for controlling the expansion and contraction of solid-state batteries by using isostatic pressure of nitrogen gas includes an air compressor, a gas separation membrane, and a sealed solid-state battery module connected in sequence through pipelines. An inlet proportional servo control valve and an outlet proportional servo control valve are respectively installed on the pipelines on both sides of the solid-state battery module; several columns of soft-pack battery cells are fixed in the solid-state battery module through corrugated elastic brackets. One end of the corrugated elastic bracket is connected to an elastic pressure strain gauge between the inner wall of the solid-state battery module, and MEMS hardware is installed in the solid-state battery module; An air compressor, an inlet proportional servo control valve, an outlet proportional servo control valve, an elastic pressure strain gauge, and MEMS hardware are jointly connected to a pressure controller, which is connected to a BMS battery management system. The BMS battery management system stores a solid-state soft-pack battery original characterization charge-discharge database, and the pressure controller loads and retrieves the original characterization database.

[0008] The features of the present invention also lie in that The MEMS hardware is based on MEMS technology and integrally integrates a nitrogen pressure sensor and a temperature sensor.

[0009] The MEMS hardware also integrally integrates a humidity sensor and an oxygen concentration sensor to real-time monitor the humidity and oxygen concentration inside the solid-state battery module and transmit the signals to the pressure controller.

[0010] The gas separation membrane uses a moisture, nitrogen and oxygen separation membrane, including a membrane housing and hollow fiber membrane filaments arranged inside the membrane housing. End caps are fixedly connected to the left and right of the membrane housing. An air inlet and a nitrogen-rich gas outlet are provided on the left end cap. An air inlet nozzle is provided on the air inlet, and a nitrogen-rich gas outlet nozzle is provided on the nitrogen-rich gas outlet. A sealing ring is provided between the membrane housing and the end cap. A rich oxygen gas and water vapor outlet is provided on the bottom side of the membrane housing. The air inlet is connected to the air compressor through a pipeline, and the nitrogen-rich gas outlet is connected to the inlet proportional servo control valve through a pipeline.

[0011] The original characterization charge-discharge data of the solid-state soft-pack battery includes charge data and discharge data. The charge data includes the battery power data during the battery charging process and the corresponding battery cell data. The battery cell data includes the temperature-related expansion and contraction data characterized by the charging experiment. The discharge data includes the battery power data during the battery discharging process and the corresponding battery cell data. The battery cell data includes the temperature-related expansion and contraction data characterized by the discharging experiment.

[0012] Based on the comparison result between the real-time expansion and contraction data detected and converted by the elastic strain gauge and the original expansion and contraction data, and the comparison result between the real-time nitrogen pressure data detected by the MEMS hardware and the set nitrogen pressure constraint range, the pressure controller controls the opening degrees of the inlet proportional servo control valve and the outlet proportional servo control valve, adjusts the nitrogen pressure inside the solid-state battery module, and controls the expansion and contraction of the solid-state battery.

[0013] The solid-state battery module includes a sealed housing. Nitrogen inlets and nitrogen outlets are respectively provided at the centers of both sides of the housing. The inlet proportional servo control valve and the outlet proportional servo control valve are respectively arranged at the nitrogen inlets and nitrogen outlets. The nitrogen inlet proportional servo control valve is connected to the gas separation membrane.

[0014] Four elastic pressure strain gauges are respectively installed at the four corners of the shell on the same side as the nitrogen inlet, and battery cell support fixing blocks are respectively installed at the four corners of the shell on the same side as the nitrogen outlet. One end of the corrugated elastic support is connected to the battery cell support fixing block, and the other end is connected to the corresponding elastic pressure strain gauge. Several columns of battery cells are correspondingly installed between the V-shaped insides of the upper and lower corrugated elastic supports.

[0015] Each soft-pack battery cell consists of a positive electrode, an electrolyte, and a negative electrode. The negative electrode and the positive electrode use the electrolyte as an ion conduction medium.

[0016] Another technical solution adopted by the present invention is a method for controlling the expansion and contraction of a solid-state battery using nitrogen isostatic pressure. The above-mentioned system for controlling the expansion and contraction of a solid-state battery using nitrogen isostatic pressure is adopted. Specifically: According to the original characterization charge and discharge data of the solid-state soft-pack battery in the BMS battery management system, a nitrogen pressure constraint range, an expansion and contraction safety data threshold, a low-temperature threshold, and a high-temperature threshold are preset. During charging and discharging, the pressure controller reads the real-time charge and discharge signals of the battery cells from the in-vehicle BMS battery management system and controls the start and stop of the air compressor at the same time. The elastic strain gauge detects its own deformation displacement in real time, converts the signal into a voltage signal through a strain bridge circuit, and after the voltage signal is amplified by an amplifier and filtered by a filter circuit, it is converted into a digital signal through an analog-to-digital converter, that is, the real-time expansion and contraction data is transmitted to the pressure controller. At the same time, the MEMS hardware detects the nitrogen pressure in the solid-state battery module in real time and transmits it to the pressure controller. The pressure controller compares the real-time expansion and contraction data of the elastic strain gauge with the original expansion and contraction data, and at the same time compares the real-time nitrogen pressure with the preset nitrogen pressure constraint range, and automatically controls the opening degree of the nitrogen inlet proportional servo control valve or the outlet proportional servo control valve according to the comparison result.

[0017] The feature of another technical solution of the present invention also lies in that During charging, the BMS battery management system transmits the charging signal to the pressure controller, controls the air compressor to start, closes the outlet proportional servo control valve. The elastic strain gauge detects its own deformation displacement in real time, converts the signal into a voltage signal through the strain bridge circuit. The voltage signal is amplified by the amplifier and filtered by the filter circuit, and then converted into a digital signal through the analog-to-digital converter, that is, the real-time expansion and contraction data is transmitted to the pressure controller. At the same time, the MEMS hardware detects the nitrogen pressure in the solid-state battery module in real time and transmits it to the pressure controller. The pressure controller compares the real-time expansion and contraction data with the original characteristic expansion and contraction data of the battery cell, and at the same time compares the real-time nitrogen pressure with the preset nitrogen pressure constraint range. If the real-time expansion and contraction data is greater than the original characteristic expansion and contraction data of the battery cell, the pressure controller controls the opening of the nitrogen inlet proportional servo control valve to increase until the real-time expansion and contraction data is within the range of the original characteristic expansion and contraction data of the battery cell; if the real-time nitrogen pressure detected by the MEMS hardware is less than the minimum value of the preset nitrogen pressure constraint range, it controls the opening of the nitrogen inlet proportional servo control valve to increase, and fills nitrogen into the solid-state battery module to pressurize. If the real-time nitrogen pressure detected by the MEMS hardware is greater than the maximum value of the preset nitrogen pressure constraint range, it controls the nitrogen inlet proportional servo control valve and the air compressor to close and stop nitrogen filling; During discharging, the BMS battery management system transmits the discharging signal to the pressure controller, controls the air compressor and the nitrogen inlet proportional servo control valve to close. The elastic strain gauge detects its own deformation displacement in real time, converts the signal into a voltage signal through the strain bridge circuit. The voltage signal is amplified by the amplifier and filtered by the filter circuit, and then converted into a digital signal through the analog-to-digital converter, that is, the real-time expansion and contraction data is transmitted to the pressure controller. At the same time, the MEMS hardware detects the nitrogen pressure in the solid-state battery module in real time and transmits it to the pressure controller. The pressure controller compares the real-time expansion and contraction data with the original characteristic expansion and contraction data of the battery cell, and at the same time compares the real-time nitrogen pressure with the preset nitrogen pressure constraint range. If the real-time expansion and contraction data is less than the original characteristic expansion and contraction data of the battery cell, the pressure controller controls the opening of the outlet proportional servo control valve to increase until the real-time expansion and contraction data is within the range of the original characteristic expansion and contraction data of the battery cell; if the real-time nitrogen pressure detected by the MEMS hardware is greater than the maximum value of the preset nitrogen pressure constraint range, it controls the opening of the outlet proportional servo control valve to increase and relieve pressure until the real-time nitrogen pressure is within the preset nitrogen pressure constraint range, and then closes the outlet proportional servo control valve; During the charging and discharging process, if the real-time temperature detected by the MEMS hardware in the solid-state battery module is lower than the low temperature threshold or higher than the high temperature threshold, the pressure controller sends a fault warning signal to the BMS battery management system; if the real-time expansion and contraction data detected by the elastic strain gauge exceeds the expansion and contraction safety data threshold, the pressure controller sends a fault warning signal to the EMS battery management system.

[0018] The beneficial effects of the present invention are: The system for controlling the expansion and contraction of a solid-state battery using nitrogen isostatic pressing of the present invention is provided with an air compressor and a gas separation membrane to separate dry, high-purity, high-pressure nitrogen, avoiding the possibility of moisture and oxygen entering the solid-state soft-pack battery cell. Combining MEMS hardware and a pressure controller to control the nitrogen filling and pressurization in the solid-state battery pack module, generating an isostatic pressing precision omnidirectional pressure constraint to achieve closed-loop pressure control. Filling the in-vehicle solid-state battery pack with dry nitrogen will greatly improve the safety redundancy design of the high-voltage (such as above 1000V) live components in the battery pack, making the internal structure of the battery pack compact, with fewer accessories and lighter weight, and improving the weight density of the battery pack. The method for controlling the expansion and contraction of a solid-state battery using nitrogen isostatic pressing of the present invention. During the charge and discharge cycle of the solid-state battery, the electrolyte and electrode materials will expand and contract, resulting in the failure of the solid-solid interface. The system for controlling the expansion and contraction of a solid-state battery using nitrogen isostatic pressing can accurately and uniformly apply isostatic pressure omnidirectionally around the solid-state soft-pack battery cell, maintaining the close contact between the electrode and the electrolyte, reducing the voids and stress concentration caused by volume expansion, thereby reducing the interfacial impedance and the risk of lithium dendrite growth, and increasing the battery life. Brief Description of the Drawings

[0019] Figure 1 is the schematic diagram of the principle of the system for controlling the expansion and contraction of a solid-state battery using nitrogen isostatic pressing of the present invention; Figure 2 is the schematic structural diagram of the solid-state battery module in the system for controlling the expansion and contraction of a solid-state battery using nitrogen isostatic pressing of the present invention; Figure 3 is the schematic structural diagram of the battery cell in the system for controlling the expansion and contraction of a solid-state battery using nitrogen isostatic pressing of the present invention; Figure 4 is the schematic structural diagram of the gas separation membrane in the system for controlling the expansion and contraction of a solid-state battery using nitrogen isostatic pressing of the present invention; Figure 5 is the flowchart of the method for controlling the expansion and contraction of a solid-state battery using nitrogen isostatic pressing of the present invention.

[0020] In the figures, 1. housing, 2. inlet proportional servo control valve, 3. outlet proportional servo control valve, 4. battery cell support fixing block, 5. elastic pressure strain gauge, 6. corrugated elastic support, 7. MEMS hardware, 8. battery cell, 9. negative electrode, 10. positive electrode, 11. electrolyte, 12. air compressor, 13. gas separation membrane, 13-1. air inlet, 13-2. nitrogen-rich gas outlet, 13-3. sealing ring, 13-4. hollow fiber membrane filament, 13-5. membrane housing, 13-6. oxygen-rich gas and water vapor outlet, 13-7. left end cover, 13-8. air inlet nozzle, 13-9. nitrogen-rich gas outlet nozzle, 13-10. right end cover; 14. pressure controller, 91. contact interface between the negative electrode and the electrolyte, 101. contact interface between the positive electrode and the electrolyte. Detailed Embodiments

[0021] The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0022] Example 1 The system for controlling the expansion and contraction of a solid-state battery by using isostatic pressing with nitrogen gas according to the present invention has a structure as shown in Figure 1 and Figure 2 and includes a small air compressor 12, a gas separation membrane 13, and a sealed solid-state battery module that are connected in sequence through pipelines. As shown in Figure 2 and shown, the solid-state battery module includes a sealed housing 1. A nitrogen inlet is provided at the center of the left side of the housing 1, and an inlet proportional servo control valve 2 is installed at the nitrogen inlet. A nitrogen outlet is provided at the center of the right side, and an outlet proportional servo control valve 3 is installed at the nitrogen outlet. The nitrogen inlet proportional servo control valve 2 is connected to the gas separation membrane 13 through a pipeline.

[0023] An elastic pressure strain gauge 5 is respectively installed at the four corners on the left side inside the housing 1, and a battery cell support fixing block 4 is respectively installed at the four inner corners on the right side. One end of a corrugated elastic support 6 is connected to the battery cell support fixing block 4, and the other end is connected to the corresponding elastic pressure strain gauge 5. A number of columns of battery cells 8 are correspondingly installed between the V-shaped inner sides of the upper and lower corrugated elastic supports 6. The soft-pack battery cells 8 are fixed by the corrugated elastic supports 6; A MEMS hardware 7 is installed inside the solid-state battery module. The MEMS hardware 7 is based on MEMS technology and integrally integrates a nitrogen gas pressure sensor and a temperature sensor to detect the pressure and temperature in real time.

[0024] The air compressor 12, the inlet proportional servo control valve 2, the outlet proportional servo control valve 3, the elastic pressure strain gauge 5, and the MEMS hardware 7 are all connected to a pressure controller 14 through a CAN bus. The pressure controller 14 is connected to a vehicle-mounted battery pack BMS battery management system through a CAN bus. The BMS battery management system stores the original characterization charge and discharge data of the solid-state soft-pack battery, and the pressure controller 14 can load and retrieve the original characterization charge and discharge data.

[0025] The elastic strain gauge 5 detects its own deformation displacement in real time, converts the signal into a voltage signal through a strain bridge circuit, and after the voltage signal is amplified by an amplifier and filtered by a filter circuit, it is converted into a digital signal through an analog-to-digital converter, that is, the real-time expansion and contraction data is transmitted to the pressure controller 14.

[0026] Example 2 On the basis of Example 1, as shown in Figure 3As shown, each pouch cell 8 is composed of a negative electrode 9, a positive electrode 10, and an electrolyte 11. The negative electrode 9 and the positive electrode 10 use the electrolyte 11 as an ion conduction medium. A negative electrode and electrolyte contact interface 91 is formed between the negative electrode 9 and the electrolyte 11, and a positive electrode and electrolyte contact interface 101 is formed between the positive electrode 10 and the electrolyte 11. A number of solid-state battery cells 8 are sealed by a solid-state battery module housing 1.

[0027] During the charging process of the pouch cell 8, lithium ions are embedded in the negative electrode 9, causing the negative electrode 9 to expand, thereby increasing the thickness of the battery; during discharging, lithium ions are removed from the negative electrode 9, and the battery thickness decreases.

[0028] During the charge-discharge cycle of the solid-state battery, the electrodes or the electrolyte will expand and contract repeatedly. As the number of charge-discharge cycles accumulates, the impedance of the negative electrode and electrolyte contact interface 91 or the positive electrode and electrolyte contact interface 101 increases, which easily leads to cell failure and battery damage. Filling nitrogen gas into the solid-state battery module and applying isostatic pressure with all-round, uniform, and precise pressure around the cells can maintain the close contact between the electrodes and the electrolyte, reduce the voids and stress concentration caused by volume expansion, thereby reducing the interface impedance and the risk of lithium dendrite growth, and increasing the battery life. Example 3 Based on Example 2, as Figure 4 shown, the gas separation membrane 13 adopts a moisture and nitrogen-oxygen separation membrane, including a membrane housing 13-5 and polymer hollow fiber membrane filaments 13-4 arranged inside the membrane housing 13-5. The left end cover 13-7 and the right end cover 13-10 are fixedly connected to the left and right of the membrane housing 13-5. An air inlet 13-1 and a nitrogen-rich gas outlet 13-2 are opened on the left end cover 13-7. An air inlet nozzle 13-8 is arranged on the air inlet 13-1, and a nitrogen-rich gas outlet nozzle 13-9 is arranged on the nitrogen-rich gas outlet 13-2. A sealing ring 13-3 for sealing is arranged between the membrane housing 13-5 and the end cover. A nitrogen-oxygen-rich gas and moisture outlet 13-6 is opened on the bottom side of the membrane housing 13-5. The air inlet 13-1 is connected to the air compressor 12 through a pipeline, and the nitrogen-rich gas outlet 13-2 is connected to the inlet proportional servo control valve 2 through a pipeline. The high-temperature and high-humidity compressed air coming out of the air compressor 12 enters the membrane housing 13-5 through the air inlet 13-1 and undergoes efficient separation of moisture and oxygen through the polymer hollow fiber membrane filaments 13-4. The separated oxygen and moisture are discharged from the nitrogen-oxygen-rich gas and moisture outlet 13-6, and the separated dry, high-purity, and high-pressure nitrogen gas is discharged from the nitrogen-rich gas outlet 13-2 and enters the solid-state battery pack module, avoiding the possibility of moisture and oxygen entering the solid-state pouch cell. In addition, filling the in-vehicle solid-state battery pack with dry nitrogen will greatly improve the safety redundancy design of the high-voltage (such as above 1000V) charged components in the battery pack, making the internal structure of the battery pack compact, with fewer accessories and lighter weight, and improving the weight density of the battery pack.

[0029] Example 4 Based on Embodiment 3, the in-vehicle battery pack BMS battery management system collects and stores in real time the original characterization charging data and discharging data of the solid-state soft-pack battery. The charging data includes the battery power data during the battery charging process and the corresponding battery cell data, including the temperature-related expansion and contraction data characterized by experiments. The discharging data includes the battery power data during the battery discharging process and the corresponding battery cell data, including the temperature-related expansion and contraction data characterized by experiments. The temperature-related expansion and contraction data characterized by experiments are the original expansion and contraction data of the electrodes and electrolytes corresponding to different temperature and different power percentages obtained from the charge and discharge tests of the solid-state soft-pack battery cells before being installed in the vehicle. The pressure controller 14 controls the opening degrees of the inlet proportional servo control valve 2 and the outlet proportional servo control valve 3 according to the comparison result between the real-time expansion and contraction data of the elastic strain gauge 5 and the original expansion and contraction data in the original characterization charge and discharge data of the solid-state soft-pack battery, and the comparison result between the real-time nitrogen pressure data detected by the MEMS hardware 7 and the set nitrogen pressure constraint range, adjusts the nitrogen pressure in the solid-state battery module, and controls the expansion and contraction of the solid-state battery.

[0030] Embodiment 5 Based on Embodiment 4, a humidity sensor and an oxygen concentration sensor are also integrally integrated on the MEMS hardware 7 to monitor the humidity and oxygen concentration in the solid-state battery module in real time, and transmit the environmental data such as the real-time humidity, oxygen concentration, nitrogen pressure, and temperature to the pressure controller 14 and display them in the BMS battery management system. During the charge and discharge process, if the real-time temperature detected by the MEMS hardware 7 in the solid-state battery module is lower than the low temperature threshold (set at -40°C in this embodiment) or higher than the high temperature threshold (set at 120°C in this embodiment), the pressure controller 14 sends a fault warning signal to the BMS battery management system; if the real-time expansion and contraction data detected and converted by the elastic strain gauge 5 exceeds the expansion and contraction safety data threshold, the pressure controller 14 sends a fault warning signal to the EMS battery management system.

[0031] The present invention utilizes a nitrogen isostatic pressure control system for the expansion and contraction of solid-state batteries. The working principle is as follows: The high-temperature and high-humidity compressed air generated by the air compressor 12 enters the gas separation membrane 13 to remove the moisture and oxygen in the air, and separated high-pressure dry high-purity nitrogen is generated. During the charge and discharge process, an inlet proportional servo control valve and an outlet proportional servo control valve are arranged on both side walls of the solid-state battery module housing. The pressure controller 14 controls the opening degrees of the inlet proportional servo control valve 2 and the outlet proportional servo control valve 3 according to the comparison result between the real-time expansion and contraction data of the elastic strain gauge 5 and the original expansion and contraction data of the battery cells, and the comparison result between the real-time nitrogen pressure data monitored by the MEMS hardware 7 and the set nitrogen pressure range, adjusts the nitrogen pressure in the solid-state battery module, and controls the expansion and contraction of the solid-state battery.

[0032] During the charging process of the solid-state battery, the electrodes or electrolyte 11 of the battery cell will expand, compressing the lateral deformation displacement of the upper and lower corrugated elastic brackets 6, squeezing the battery cell bracket fixing block 4 and the elastic pressure strain gauge 5. The battery cell bracket fixing block 4 remains stationary because it is fixed to the housing 1 of the solid-state battery module. The elastic pressure strain gauge 5 will be subjected to force. When the real-time expansion and contraction data detected and converted by the elastic pressure strain gauge 5 is greater than the original represented expansion and contraction data, the pressure controller 14 controls the opening of the nitrogen inlet control valve 2 to increase. Dry high-purity nitrogen enters the housing 1 of the solid-state battery module from the nitrogen inlet proportional servo control valve 2, and isostatically presses the outer surface of the solid-state battery cell 8 in the internal space of the module in a full-range, precise, non-discriminatory and uniform manner. When the MEMS hardware 7 detects that the nitrogen pressure in the solid-state battery module increases to the preset nitrogen pressure range, it controls the nitrogen inlet control valve 2 to close and stop pressurization.

[0033] During the discharging process of the solid-state battery, the electrodes or electrolyte 11 of the battery cell will contract, driving the lateral contraction of the upper and lower corrugated elastic brackets 6, and the force on the elastic pressure strain gauge 5 decreases. When the real-time expansion and contraction data detected and converted by the elastic pressure strain gauge 5 is less than the original represented expansion and contraction data, the pressure controller 14 increases the opening of the nitrogen outlet control valve 3 until the real-time expansion and contraction data is within the range of the original represented expansion and contraction data. Nitrogen is released from the nitrogen outlet control valve 3. When the MEMS hardware 7 detects that the nitrogen pressure value in the housing 1 of the solid-state battery module is within the preset pressure constraint range, the nitrogen outlet control valve 3 is closed.

[0034] Example 6 A method for controlling the expansion and contraction of a solid-state battery using nitrogen isostatic pressure, which adopts the system for controlling the expansion and contraction of a solid-state battery using nitrogen isostatic pressure in Embodiment 5 of the present invention. Specifically: According to the original represented charging data and discharging data of the solid-state soft-pack battery stored in the BMS battery management system, preset the nitrogen pressure constraint range, expansion and contraction safety data threshold, low-temperature threshold, and high-temperature threshold. During charging and discharging, the pressure controller 14 reads the real-time charging and discharging signals of the battery cell from the in-vehicle BMS battery management system, and at the same time controls the start and stop of the air compressor 12. The elastic strain gauge 5 detects its own deformation displacement in real time, converts the signal into a voltage signal through a strain bridge circuit, and the voltage signal is amplified by an amplifier and filtered by a filter circuit and then converted into a digital signal, that is, the real-time expansion and contraction data, and transmitted to the pressure controller 14. At the same time, the MEMS hardware 7 detects the nitrogen pressure in the solid-state battery module in real time and transmits it to the pressure controller 14. The pressure controller 14 compares the real-time expansion and contraction data with the original represented expansion and contraction data of the battery cell, and at the same time compares the real-time nitrogen pressure with the preset nitrogen pressure constraint range, and automatically controls the opening of the nitrogen inlet proportional servo control valve 2 or the outlet proportional servo control valve 3 according to the comparison result.

[0035] Example 7 Based on Embodiment 6, the process is as follows Figure 5 as shown below: The preset nitrogen pressure constraint range is 0.02 - 2 MPa.

[0036] During the charging of the solid-state battery, the BMS battery management system transmits the charging signal to the pressure controller 14, controls the start of the air compressor 12, closes the outlet proportional servo control valve 3. The elastic strain gauge 5 detects its own deformation displacement in real time, converts the signal into a voltage signal through the strain bridge circuit, and after the voltage signal is amplified by the amplifier and filtered by the filter circuit, it is converted into a digital signal through the analog-to-digital converter, that is, the real-time expansion and contraction data is transmitted to the pressure controller 14. At the same time, the MEMS hardware 7 detects the nitrogen pressure in the solid-state battery module in real time and transmits it to the pressure controller 14. The pressure controller 14 compares the real-time expansion and contraction data with the original characterization expansion and contraction data of the battery cell, and at the same time compares the real-time nitrogen pressure with the preset nitrogen pressure constraint range. If the real-time expansion and contraction data is greater than the original characterization expansion and contraction data of the battery cell, the pressure controller 14 controls the opening of the nitrogen inlet proportional servo control valve 2 to increase until the real-time expansion and contraction data is within the range of the original characterization expansion and contraction data of the battery cell; if the real-time nitrogen pressure detected by the MEMS hardware 7 is less than the preset 0.02 MPa, it controls the opening of the nitrogen inlet proportional servo control valve 2 to increase, and fills the solid-state battery module with nitrogen for pressurization. If the real-time nitrogen pressure detected by the MEMS hardware 7 is greater than 2 MPa, it controls the nitrogen inlet proportional servo control valve 2 and the air compressor 12 to close and stops nitrogen filling; As the charging progress changes, such as charging from 10% to 100%, the pressure controller 14 automatically controls the opening of the nitrogen inlet proportional servo control valve 2 by comparing the data change of the real-time expansion displacement measurement value of the elastic pressure strain gauge 5 with the physical characterization data of the battery cell, adjusts the nitrogen pressure in the solid-state battery module housing 1, and performs omnidirectional isostatic pressurization on the battery cell 8, so that the expansion displacement of the elastic pressure strain gauge 5 does not exceed the expansion and contraction safety data threshold.

[0037] During discharging, the BMS battery management system transmits a discharging signal to the pressure controller 14 to control the air compressor 12 and the nitrogen inlet proportional servo control valve 2 to close. The elastic strain gauge 5 detects its own deformation displacement in real time, converts the signal into a voltage signal through a strain bridge circuit, and after the voltage signal is amplified by an amplifier and filtered by a filter circuit, it is converted into a digital signal through an analog-to-digital converter, that is, the real-time expansion and contraction data is transmitted to the pressure controller 14. At the same time, the MEMS hardware 7 detects the nitrogen pressure in the solid-state battery module in real time and transmits it to the pressure controller 14. The pressure controller 14 compares the real-time expansion and contraction data with the original characteristic expansion and contraction data of the battery cell, and at the same time compares the real-time nitrogen pressure with the preset nitrogen pressure constraint range. If the real-time expansion and contraction data is less than the comparison between the real-time expansion and contraction data and the original characteristic expansion and contraction data of the battery cell by the pressure controller 14, the pressure controller 14 controls the opening degree of the outlet proportional servo control valve 3 to increase until the real-time expansion and contraction data is within the range of the original characteristic expansion and contraction data of the battery cell; if the real-time nitrogen pressure detected by the MEMS hardware 7 is greater than 2 MPa, it controls the opening degree of the outlet proportional servo control valve 3 to increase and relieve pressure until the real-time nitrogen pressure is within the range of 0.02 - 2 MPa, and then closes the outlet proportional servo control valve 3; During the charge and discharge process, if the MEMS hardware 7 detects that the real-time temperature in the solid-state battery module is lower than the high and low temperature thresholds (the low temperature threshold is set to -40 °C in this embodiment) or higher than the high temperature threshold (the high temperature threshold is set to 120 °C in this embodiment), the pressure controller 14 sends a fault warning signal to the BMS battery management system; if the real-time expansion and contraction data detected by the elastic strain gauge 5 exceeds the expansion and contraction safety data threshold, the pressure controller 14 sends a fault warning signal to the EMS battery management system.

[0038] The method for controlling the expansion and contraction of a solid-state battery using nitrogen isostatic pressing has the following advantages: Through a gas separation membrane, high-temperature and high-humidity air from a small air compressor is efficiently separated from moisture and oxygen. The generated high-pressure dry and high-purity nitrogen passes through a nitrogen inlet proportional servo control valve, and the pressure controller controls the opening of the control valve to further control the charging and discharging of the high-pressure dry and high-purity nitrogen. By precisely controlling the high-purity nitrogen to enter the space around the soft-pack battery cells elastically fixed in the sealed housing of the solid-state battery module, isostatic pressure can be applied omnidirectionally, precisely, and uniformly, maintaining the close contact between the electrode and the electrolyte, reducing voids and stress concentration caused by volume expansion or contraction, thereby reducing the interfacial impedance and the risk of lithium dendrite growth, and increasing the battery life. The MEMS hardware installed in the sealed housing of the solid-state battery module will quickly and real-time collect data on the nitrogen pressure, humidity, and oxygen concentration in the sealed housing of the solid-state battery module, and send all the data to the pressure controller through the CAN bus. Combining the data of repeated expansion and contraction accumulated by the solid-state battery cells during long-term charging and discharging, a closed-loop intelligent membrane nitrogen generation gas isostatic pressing control method for controlling the expansion and contraction of the solid-state soft-pack battery is finally formed, realizing the control of the expansion and contraction of the solid-state soft-pack battery during charging and discharging, and greatly improving the working performance and life reliability of the solid-state battery soft-pack cells. The overall structure is simple, small in size, light in weight, and lower in cost.

[0039] The scope of protection required by the present invention is not limited to the above specific embodiments. Any technical solution based on the core concept of the present invention, including but not limited to equivalent replacement of specific structures, combination of technical features, or expansion of the application field, as long as it can achieve the same technical effect as the present invention, shall fall within the protection scope of this patent.

Claims

1. A system for controlling the expansion and contraction of a solid-state battery using nitrogen isostatic pressing, characterized in that, It includes an air compressor (12), a gas separation membrane (13), and a sealed solid-state battery module that are connected in sequence through pipelines. An inlet proportional servo control valve (2) and an outlet proportional servo control valve (3) are respectively installed on the pipelines on both sides of the solid-state battery module; several columns of soft-pack battery cells (8) are fixed in the solid-state battery module through corrugated elastic brackets (6). One end of the corrugated elastic bracket (6) is connected to an elastic pressure strain gauge (5) between the inner wall of the solid-state battery module, and MEMS hardware (7) is installed in the solid-state battery module; The air compressor (12), the inlet proportional servo control valve (2), the outlet proportional servo control valve (3), the elastic pressure strain gauge (5), and the MEMS hardware (7) are jointly connected to a pressure controller (14). The pressure controller (14) is connected to the BMS battery management system. The BMS battery management system stores the original characterization charge and discharge data of the solid-state soft-pack battery, and the pressure controller (14) loads and retrieves the original characterization data.

2. The solid-state battery expansion and contraction control system using nitrogen isostatic pressing according to claim 1, wherein The MEMS hardware (7) is based on MEMS technology and is integrally integrated with a nitrogen pressure sensor and a temperature sensor.

3. The system for controlling the expansion and contraction of a solid-state battery by using nitrogen isostatic pressing according to claim 2, wherein The MEMS hardware (7) is also integrally integrated with a humidity sensor and an oxygen concentration sensor to real-time monitor the humidity and oxygen concentration inside the solid-state battery module and transmit the signals to the pressure controller (14).

4. The system for controlling the expansion and contraction of a solid-state battery by using nitrogen isostatic pressing according to claim 1, wherein, The gas separation membrane (13) adopts a moisture, nitrogen and oxygen separation membrane, including a membrane housing (13-5) and hollow fiber membrane filaments (13-4) arranged inside the membrane housing (13-5). End caps are fixedly connected to the left and right of the membrane housing (13-5). An air inlet (13-1) and a nitrogen-rich gas outlet (13-2) are opened on the left end cap. An air inlet nozzle (13-8) is arranged on the air inlet (13-1), and a nitrogen-rich gas outlet nozzle (13-9) is arranged on the nitrogen-rich gas outlet (13-2). A sealing ring (13-3) is arranged between the membrane housing (13-5) and the end cap. A nitrogen-rich oxygen gas and water vapor outlet is opened at the bottom side of the membrane housing (13-5). The air inlet (13-1) is connected to the air compressor (12) through a pipeline, and the nitrogen-rich gas outlet (13-2) is connected to the inlet proportional servo control valve (2) through a pipeline.

5. The solid-state battery expansion and contraction control system using nitrogen isostatic pressing according to claim 1, wherein The original characterization charge and discharge data of the solid-state soft-pack battery include charge data and discharge data. The charge data includes the battery power data during the battery charging process and the corresponding battery cell data. The battery cell data includes the temperature-related expansion and contraction data characterized in the charging experiment. The discharge data includes the battery power data during the battery discharging process and the corresponding battery cell data. The battery cell data includes the temperature-related expansion and contraction data characterized in the discharging experiment; The pressure controller (14) controls the opening degrees of the inlet proportional servo control valve (2) and the outlet proportional servo control valve (3) according to the comparison result between the real-time expansion and contraction data detected and converted by the elastic strain gauge (5) and the original expansion and contraction data, and the comparison result between the real-time nitrogen pressure data detected by the MEMS hardware (7) and the set nitrogen pressure constraint range, adjusts the nitrogen pressure inside the solid-state battery module, and controls the expansion and contraction of the solid-state battery.

6. The system for controlling the expansion and contraction of a solid-state battery using nitrogen isostatic pressing according to claim 1, characterized in that The solid-state battery module includes a sealed housing (1). Nitrogen inlets and nitrogen outlets are respectively provided at the centers of both sides of the housing (1). An inlet proportional servo control valve (2) and an outlet proportional servo control valve (3) are respectively arranged at the nitrogen inlets and nitrogen outlets. The nitrogen inlet proportional servo control valve (2) is communicated with a gas separation membrane (13).

7. The system for controlling the expansion and contraction of a solid-state battery by using nitrogen isostatic pressing according to claim 6, characterized in that Four elastic pressure strain gauges (5) are respectively installed at the four corners of the housing (1) on the same side as the nitrogen inlet. Battery cell support fixing blocks (4) are respectively installed at the four corners of the housing (1) on the same side as the nitrogen outlet. One end of a corrugated elastic support (6) is connected to the battery cell support fixing block (4), and the other end is connected to the corresponding elastic pressure strain gauge (5). A number of columns of battery cells (8) are correspondingly installed between the V-shaped inner sides of the upper and lower corrugated elastic supports (6).

8. The system for controlling the expansion and contraction of a solid-state battery using nitrogen isostatic pressing according to claim 1, wherein Each soft-pack battery cell (8) is composed of a positive electrode (10), an electrolyte (11), and a negative electrode (9). The negative electrode (9) and the positive electrode (10) use the electrolyte (11) as an ion conduction medium.

9. A method for controlling the expansion and contraction of a solid-state battery using nitrogen isostatic pressing, adopting the system for controlling the expansion and contraction of a solid-state battery using nitrogen isostatic pressing as described in any one of claims 1-8, characterized in that, Specifically: According to the original charge and discharge data of the solid-state soft-pack battery in the BMS battery management system, a nitrogen pressure constraint range, an expansion and contraction safety data threshold, a low-temperature threshold, and a high-temperature threshold are preset. During charge and discharge, the pressure controller (14) reads the real-time charge and discharge signals of the battery cells from the in-vehicle BMS battery management system, and at the same time controls the start and stop of the air compressor (12). The elastic strain gauge (5) detects its own deformation displacement in real time, converts the signal into a voltage signal through a strain bridge circuit, and after the voltage signal is amplified by an amplifier and filtered by a filter circuit, it is converted into a digital signal through an analog-to-digital converter, that is, the real-time expansion and contraction data is transmitted to the pressure controller (14). At the same time, the MEMS hardware (7) detects the nitrogen pressure in the solid-state battery module in real time and transmits it to the pressure controller (14). The pressure controller (14) compares the real-time expansion and contraction data with the original expansion and contraction data, and at the same time compares the real-time nitrogen pressure with the preset nitrogen pressure constraint range, and automatically controls the opening degree of the nitrogen inlet proportional servo control valve (2) or the outlet proportional servo control valve (3) according to the comparison result.

10. The method for controlling the expansion and contraction of a solid-state battery by using nitrogen isostatic pressing according to claim 9, characterized in that, During charging, the BMS battery management system transmits the charging signal to the pressure controller (14), controls the air compressor (12) to start, closes the outlet proportional servo control valve (3), the elastic strain gauge (5) detects its own deformation displacement in real time, converts the signal into a voltage signal through the strain bridge circuit, and after the voltage signal is amplified by the amplifier and filtered by the filter circuit, it is converted into a digital signal through the analog-to-digital converter, that is, the real-time expansion and contraction data is transmitted to the pressure controller (14). At the same time, the MEMS hardware (7) detects the nitrogen pressure in the solid-state battery module in real time and transmits it to the pressure controller (14). The pressure controller (14) compares the real-time expansion and contraction data with the original characteristic expansion and contraction data of the battery cell, and at the same time compares the real-time nitrogen pressure with the preset nitrogen pressure constraint range. If the real-time expansion and contraction data is greater than the original characteristic expansion and contraction data of the battery cell, the pressure controller (14) controls the opening of the nitrogen inlet proportional servo control valve (2) to increase until the real-time expansion and contraction data is within the range of the original characteristic expansion and contraction data of the battery cell; if the real-time nitrogen pressure detected by the MEMS hardware (7) is less than the minimum value of the preset nitrogen pressure constraint range, it controls the opening of the nitrogen inlet proportional servo control valve (2) to increase and fills nitrogen into the solid-state battery module to pressurize. If the real-time nitrogen pressure detected by the MEMS hardware (7) is greater than the maximum value of the preset nitrogen pressure constraint range, it controls the nitrogen inlet proportional servo control valve (2) and the air compressor (12) to close and stops nitrogen filling; During discharging, the BMS battery management system transmits the discharging signal to the pressure controller (14), controls the air compressor (12) and the nitrogen inlet proportional servo control valve (2) to close, the elastic strain gauge (5) detects its own deformation displacement in real time, converts the signal into a voltage signal through the strain bridge circuit, and after the voltage signal is amplified by the amplifier and filtered by the filter circuit, it is converted into a digital signal through the analog-to-digital converter, that is, the real-time expansion and contraction data is transmitted to the pressure controller (14). At the same time, the MEMS hardware (7) detects the nitrogen pressure in the solid-state battery module in real time and transmits it to the pressure controller (14). The pressure controller (14) compares the real-time expansion and contraction data with the original characteristic expansion and contraction data of the battery cell, and at the same time compares the real-time nitrogen pressure with the preset nitrogen pressure constraint range. If the real-time expansion and contraction data is less than the original characteristic expansion and contraction data of the battery cell, the pressure controller (14) controls the opening of the outlet proportional servo control valve (3) to increase until the real-time expansion and contraction data is within the range of the original characteristic expansion and contraction data of the battery cell; if the real-time nitrogen pressure detected by the MEMS hardware (7) is greater than the maximum value of the preset nitrogen pressure constraint range, it controls the opening of the outlet proportional servo control valve (3) to increase and relieve pressure until the real-time nitrogen pressure is within the preset nitrogen pressure constraint range, and then closes the outlet proportional servo control valve (3); During the charge and discharge process, if the MEMS hardware (7) detects that the real-time temperature inside the solid-state battery module is lower than the low-temperature threshold or higher than the high-temperature threshold, the pressure controller (14) sends a fault warning signal to the BMS battery management system; if the elastic strain gauge (5) detects that the real-time expansion and contraction data exceeds the expansion and contraction safety data threshold, then the pressure controller (14) sends a fault warning signal to the EMS battery management system.

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