A pre-warning type current cut-off cover plate for large capacity sodium ion battery

Abstract

The application belongs to the technical field of sodium ion batteries, and provides a pre-warning type current cut-off cover plate for a large-capacity sodium ion battery, which comprises: determining whether the battery enters a 0V wake-up mode, applying an initial wake-up current and collecting surface expansion stress, and calculating a stress time change rate; when the SOC is lower than a safety reconstruction threshold and the stress change rate exceeds a preset threshold, a pre-warning is generated and the initial current is cut off, the intermittent micro-current pulse repair loop is switched to, and the main charging loop is reconnected after the stress change rate meets the standard. The application realizes early warning and safety repair of gas expansion in the 0V wake-up period based on mechanical and electrochemical coupling monitoring, avoids battery damage, improves the wake-up charging safety of the large-capacity sodium ion battery, and promotes its large-scale application.

Description

Technical Field

[0001] This invention belongs to the field of sodium-ion battery technology, specifically a warning current cut-off cover for high-capacity sodium-ion batteries. Background Technology

[0002] With the development of the new energy industry, sodium-ion batteries, due to their abundant sodium resources, low cost, and excellent low-temperature performance, have broad application prospects in large-scale energy storage and low-speed electric vehicles. Unlike lithium-ion batteries, both the positive and negative electrode current collectors of sodium-ion batteries can be made of aluminum foil, thus possessing the unique advantage of 0V storage and transportation safety, eliminating the risk of short circuits and fires during storage and transportation.

[0003] However, large-capacity sodium-ion batteries, after long-term storage at 0V, pose hidden safety hazards during their first awakening and charging, becoming a bottleneck for industry development. Long-term storage at 0V leads to aging and instability of the hard carbon anode SEI film. When a conventional high current is applied directly to awaken it, severe polarization causes violent and uneven SEI film reconstruction, accompanied by electrolyte decomposition producing gas and local mechanical expansion stress.

[0004] The compact internal space of high-capacity battery cells prevents the timely release of gas generation and expansion stress. When the stress exceeds the mechanical yield limit of the separator, it can trigger a micro-short circuit between the positive and negative electrodes. This micro-short circuit is initially inconspicuous but can later evolve into an internal short circuit and thermal runaway, shortening battery life and creating potential safety hazards.

[0005] Existing battery safety protection and current cut-off methods have blind spots. Mainstream BMS and cut-off logic are only based on voltage, current and surface temperature thresholds to trigger protection, which cannot deal with the above-mentioned hidden dangers: during the wake-up period, the battery terminal voltage and current do not reach the protection threshold, and the thermal hysteresis effect of large-capacity cells causes the surface temperature to fail to reflect internal damage in time, making it impossible to provide early warning.

[0006] In summary, traditional technologies cannot address the potential microscopic mechanical stress damage during the 0V wake-up period of sodium-ion batteries. There is an urgent need in the field for a pre-warning current cutoff method that transcends the limitations of voltage / temperature monitoring and is based on the coupling of mechanics and electrochemistry to prevent micro-short circuit risks and promote its large-scale application. Therefore, this invention provides a pre-warning current cutoff cover for high-capacity sodium-ion batteries. Summary of the Invention

[0007] In order to overcome the shortcomings of the prior art, at least one technical problem raised in the background art is solved.

[0008] The technical solution adopted by this invention to solve its technical problem is: One objective of this invention is to provide a warning-type current cut-off cover for high-capacity sodium-ion batteries, comprising: 0V wake-up charging mode determination module: acquires the initial terminal voltage of the sodium-ion battery, compares the initial terminal voltage of the sodium-ion battery with the preset extremely low voltage threshold, and determines whether the sodium-ion battery has entered the 0V wake-up charging mode. Expansion stress acquisition module: If the sodium-ion battery enters the 0V wake-up charging mode, an initial wake-up current is applied to the sodium-ion battery, and the expansion stress value on the surface of the sodium-ion battery is acquired. Expansion stress time change rate calculation module: Calculates the time change rate of expansion stress value on the surface of sodium-ion battery; Gas production expansion warning signal generation module: When the state of charge (SOC) of the sodium-ion battery is lower than the preset safety reconfiguration threshold, and the time change rate of the expansion stress value on the surface of the sodium-ion battery is greater than the preset stress threshold, a gas production expansion warning signal is generated. Charging circuit switching and repair charging module: Based on the gas expansion warning signal, the current initial wake-up current is cut off, and the intermittent micro-current pulse repair circuit is switched to charge until the time change rate of the expansion stress value on the sodium-ion battery surface drops below the preset stress threshold, and the charging circuit is reconnected.

[0009] As a further improvement of the present invention, the specific process for obtaining the initial terminal voltage of the sodium-ion battery is as follows: When the sodium-ion battery is at rest, the terminal voltage of the positive and negative terminals of the sodium-ion battery is collected to obtain the initial terminal voltage of the sodium-ion battery.

[0010] As a further improvement of the present invention, the specific process for determining whether the sodium-ion battery has entered the 0V wake-up charging mode is as follows: The initial terminal voltage of the sodium-ion battery is compared with a preset extremely low voltage threshold. If the initial terminal voltage of the sodium-ion battery is greater than or equal to the preset extremely low voltage threshold, the sodium-ion battery is determined to be in a normal low voltage state. If the initial terminal voltage of the sodium-ion battery is less than the preset extremely low voltage threshold, it is determined that the sodium-ion battery has entered the 0V wake-up charging mode.

[0011] As a further improvement of the present invention, the specific process of applying the initial wake-up current to the sodium-ion battery is as follows: After determining that the sodium-ion battery has entered the 0V wake-up charging mode, the wake-up charging circuit is switched, and the wake-up charging circuit is connected to the positive and negative terminals of the sodium-ion battery. The initial wake-up current adopts constant current mode, and the magnitude of the initial wake-up current is 0.01C-0.05C, where C is the rated capacity of the sodium battery.

[0012] As a further improvement of the present invention, the specific process for collecting the expansion stress value on the surface of the sodium-ion battery is as follows: High-precision strain gauges are uniformly attached to the upper surface, lower surface, and middle of the side of the sodium-ion battery to collect expansion stress values.

[0013] As a further improvement of the present invention, the specific process for calculating the time-varying rate of change of the expansion stress value on the surface of the sodium-ion battery is as follows: The expansion stress values ​​on the surface of sodium-ion batteries and the corresponding acquisition timestamps for the expansion stress values ​​on the surface of each group of sodium-ion batteries were obtained. The expansion stress values ​​on the surface of sodium-ion batteries acquired at two consecutive adjacent timestamps were selected and denoted as follows: Expansion stress value and Expansion stress value ,in Calculate the time interval ; through formula The time-varying rate of change of the expansion stress value on the surface of the sodium-ion battery was calculated. .

[0014] As a further improvement of the present invention, the specific process of generating the gas production expansion early warning signal is as follows: The system acquires the state of charge (SOC) value of the sodium-ion battery and the time rate of change of the expansion stress value on the surface of the sodium-ion battery. If the SOC value of the sodium-ion battery is lower than the preset safety reconfiguration threshold and the time rate of change of the expansion stress value on the surface of the sodium-ion battery is greater than the preset stress threshold, a gas production expansion warning signal is generated.

[0015] As a further improvement of the present invention, the specific process of switching to the intermittent microcurrent pulse repair circuit for charging is as follows: Based on the gas expansion warning signal, the electronic switch in the wake-up charging circuit is quickly disconnected, cutting off the currently applied initial wake-up current. After the initial wake-up current is cut off, the switching switch is activated, switching the charging circuit from the wake-up charging circuit to the intermittent micro-current pulse repair circuit.

[0016] As a further improvement of the present invention, the intermittent microcurrent pulse repair circuit is specifically as follows: The intermittent microcurrent pulse repair circuit and the wake-up charging circuit share the positive and negative terminal interfaces of the battery. The pulse current of the intermittent microcurrent pulse repair circuit is 0.005C-0.01C, where C is the rated capacity of the sodium battery.

[0017] As a further improvement of the present invention, the specific process of reconnecting the charging circuit is as follows: The time change rate of the expansion stress value on the surface of the sodium-ion battery is compared with the preset stress threshold. If the time change rate of the expansion stress value on the surface of the sodium-ion battery is still greater than or equal to the preset stress threshold, the intermittent microcurrent pulse repair charging circuit state is maintained. If the time change rate of the expansion stress value on the surface of the sodium-ion battery is lower than the preset stress threshold for three consecutive times, it is determined that the gas expansion trend of the sodium battery has been suppressed. The switching switch is activated, the intermittent micro-current pulse repair circuit is disconnected, and the charging circuit is reconnected.

[0018] The second objective of this invention is to provide a pre-warning current cutoff method for high-capacity sodium-ion batteries, comprising: Step S10: Obtain the initial terminal voltage of the sodium-ion battery, compare the initial terminal voltage of the sodium-ion battery with the preset extremely low voltage threshold, and determine whether the sodium-ion battery has entered the 0V wake-up charging mode. Step S20: If the sodium-ion battery enters the 0V wake-up charging mode, apply an initial wake-up current to the sodium-ion battery and collect the expansion stress value on the surface of the sodium-ion battery. Step S30: Calculate the rate of change of the expansion stress value on the surface of the sodium-ion battery over time; Step S40: When the state of charge (SOC) of the sodium-ion battery is lower than the preset safety reconfiguration threshold, and the time change rate of the expansion stress value on the surface of the sodium-ion battery is greater than the preset stress threshold, a gas production expansion warning signal is generated. Step S50: Based on the gas expansion warning signal, cut off the current initial wake-up current and switch to the intermittent microcurrent pulse repair circuit for charging until the time change rate of the expansion stress value on the sodium-ion battery surface drops below the preset stress threshold, and then reconnect the charging circuit.

[0019] The beneficial effects of this invention are as follows: 1. It solves the blind spot problem of traditional BMS that only triggers protection based on voltage, current, and surface temperature thresholds. By monitoring the change rate of battery surface expansion stress, it accurately identifies hidden risks such as electrolyte decomposition and gas generation and local expansion caused by SEI film reconstruction in the early stage of 0V wake-up charging. It generates early warning signals in advance when the terminal voltage and current have not reached the protection threshold and the surface temperature has not changed significantly, thus blocking the path from micro short circuit to internal short circuit and thermal runaway from the source, and greatly improving the safety of sodium-ion battery 0V wake-up charging.

[0020] 2. Reduce internal battery damage: When an abnormal gas production and expansion trend is detected, the initial wake-up current is quickly cut off and the intermittent micro-current pulse repair circuit of 0.005C-0.01C is switched, instead of directly cutting off all charging circuits. This avoids the damage to the internal battery structure caused by continuous high-current polarization, and gently repairs the aging and unstable SEI film through micro-current pulses, achieving safe reconstruction of active materials, effectively reducing internal mechanical stress damage to the battery and extending battery life.

[0021] 3. Adapted to the characteristics of sodium-ion batteries, leveraging their 0V storage advantages. Designed to address the unique 0V storage and transportation safety advantages of sodium-ion batteries, it solves the industrial development bottleneck of first-time charging after long-term 0V storage, allowing the 0V storage advantages of sodium-ion batteries to be fully utilized. At the same time, it is compatible with the structural feature of using aluminum foil for the positive and negative electrode current collectors, making it suitable for the application scenarios of high-capacity sodium-ion batteries. Attached Figure Description

[0022] The invention will now be further described with reference to the accompanying drawings.

[0023] Figure 1 This is an overall module diagram of a warning current cut-off cover plate for a large-capacity sodium-ion battery according to the present invention. Figure 2 This is a flowchart illustrating the steps of a pre-warning current cutoff method for a high-capacity sodium-ion battery according to the present invention. Detailed Implementation

[0024] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0025] Example 1 like Figure 1 As shown in the embodiment of the present invention, a warning-type current cut-off cover for a high-capacity sodium-ion battery includes: 0V wake-up charging mode determination module: acquires the initial terminal voltage of the sodium-ion battery, compares the initial terminal voltage of the sodium-ion battery with the preset extremely low voltage threshold, and determines whether the sodium-ion battery has entered the 0V wake-up charging mode. In the 0V wake-up charging mode determination module, the specific process for obtaining the initial terminal voltage of the sodium-ion battery is as follows: When the sodium-ion battery is in a quiescent state (i.e., not connected to any charging circuit and not outputting current), the voltage acquisition module is activated to acquire the terminal voltage of the positive and negative terminals of the sodium-ion battery, ensuring that there is no external current interference during the acquisition process and guaranteeing the accuracy of the initial terminal voltage data. For example, the voltage acquisition module uses a high-precision voltage sensor with an acquisition frequency set to 1-5Hz and an acquisition accuracy of not less than ±0.001V, which can effectively avoid misjudgment caused by voltage fluctuations. In the 0V wake-up charging mode determination module, the initial terminal voltage of the sodium-ion battery is compared with a preset extremely low voltage threshold. The specific process for determining whether the sodium-ion battery has entered the 0V wake-up charging mode is as follows: After acquiring the initial terminal voltage of the sodium-ion battery, the acquired initial terminal voltage of the sodium-ion battery is compared with the preset extremely low voltage threshold in real time. If the initial terminal voltage of the sodium-ion battery is greater than or equal to the preset extremely low voltage threshold, the sodium-ion battery is determined to be in a normal low voltage state. It does not need to enter the 0V wake-up charging mode and can be directly connected to the charging circuit for charging. If the initial terminal voltage of the sodium-ion battery is less than the preset extremely low voltage threshold, it is determined that the sodium-ion battery has entered a deactivated state. The 0V wake-up charging mode must be started immediately. Through the subsequent wake-up and repair process, the battery is safely restored to a normal charging state, avoiding the battery from producing gas, bulging or even being damaged due to direct conventional charging. It should be noted that the extremely low voltage threshold is preset based on the nominal voltage of the sodium-ion battery, the characteristics of the electrode material, and the safe operating range. It is usually set to 0-0.3V (which can be flexibly adjusted according to the specific battery model). The purpose of setting the extremely low voltage threshold is to accurately identify the low voltage inactivation state of the sodium-ion battery caused by over-discharge, long-term quiescence, etc., and to avoid misjudging the normal low voltage state as a state that needs to be awakened. This invention does not limit this. Expansion stress acquisition module: If the sodium-ion battery enters the 0V wake-up charging mode, an initial wake-up current is applied to the sodium-ion battery, and the expansion stress value on the surface of the sodium-ion battery is acquired. In the expansion stress acquisition module, if the sodium-ion battery enters the 0V wake-up charging mode, the specific process of applying the initial wake-up current to the sodium-ion battery is as follows: When the 0V wake-up charging mode determination module determines that the sodium-ion battery has entered the 0V wake-up charging mode, it triggers the wake-up charging circuit and controls the wake-up charging circuit to connect with the positive and negative terminals of the sodium-ion battery to ensure good circuit contact and no abnormal contact resistance. The initial wake-up current of the wake-up charging circuit adopts a constant current mode. The magnitude of the initial wake-up current is preset according to the rated capacity of the sodium-ion battery, and the value is 0.01C-0.05C (C is the rated capacity of the sodium battery). This avoids the internal polarization of the sodium-ion battery from being aggravated and abnormal gas production caused by excessive initial wake-up current. At the same time, it ensures that the initial wake-up current is sufficient to start the reaction of the active material inside the sodium-ion battery and realize low-voltage wake-up. This invention does not limit this aspect. Before applying the initial wake-up current, the wake-up charging circuit is first tested for insulation and short circuit. After confirming that there is no short circuit in the circuit and that the insulation performance meets the standard (insulation resistance is not less than 100MΩ), the initial wake-up current output is slowly started. The output is gradually increased from 50% of the initial wake-up current to the preset initial wake-up current value. The boost time is controlled within 5-10 seconds to reduce the impact of the sudden change in the initial wake-up current on the internal structure of the battery. The specific process of acquiring the expansion stress value on the surface of the sodium-ion battery in the expansion stress acquisition module is as follows: At least three high-precision strain gauges are used as expansion stress acquisition elements. The high-precision strain gauges are evenly pasted on the upper surface, lower surface and middle side of the sodium-ion battery. Before pasting the high-precision strain gauges, the battery surface is cleaned to remove surface oil and oxide layer to ensure that the strain gauges are tightly attached to the battery surface with a gap of no more than 0.01mm. This avoids acquisition errors caused by poor adhesion and enables real-time synchronous acquisition of expansion stress values. For example, the strain gauge has a measurement range of 0-5000με, a measurement accuracy of not less than ±1με, and a sampling frequency that is consistent with the parameter acquisition frequency during the initial wake-up current application process, both being 1-5Hz; Expansion stress time change rate calculation module: Calculates the time change rate of expansion stress value on the surface of sodium-ion battery; In the expansion stress time change rate calculation module, the specific process for calculating the time change rate of the expansion stress value on the sodium-ion battery surface is as follows: The expansion stress value of the sodium-ion battery surface is obtained in real time, and the collection timestamp corresponding to the expansion stress value of each group of sodium-ion batteries is recorded synchronously to ensure that the expansion stress value of the sodium-ion battery surface corresponds one-to-one with the timestamp value without deviation. The time-varying rate of change of the expansion stress value on the surface of a sodium-ion battery was calculated using the finite difference method. Specifically, the calculation method involved selecting expansion stress values ​​from two consecutive adjacent time stamps on the sodium-ion battery surface, denoted as follows: Expansion stress value and Expansion stress value ,in Calculate the time interval ; through formula The time-varying rate of change of the expansion stress value on the surface of the sodium-ion battery was calculated. ; Gas production expansion warning signal generation module: When the state of charge (SOC) of the sodium-ion battery is lower than the preset safety reconfiguration threshold, and the time change rate of the expansion stress value on the surface of the sodium-ion battery is greater than the preset stress threshold, a gas production expansion warning signal is generated. In the gas production expansion early warning signal generation module, when the state of charge (SOC) of the sodium-ion battery is lower than the preset safety reconfiguration threshold, and the time change rate of the expansion stress value on the surface of the sodium-ion battery is greater than the preset stress threshold, the specific process for generating the gas production expansion early warning signal is as follows: Real-time acquisition of the state of charge (SOC) value of sodium-ion batteries and the time rate of change of the expansion stress value on the surface of sodium-ion batteries. If the state of charge (SOC) value of the sodium-ion battery is lower than the safety reconfiguration threshold, and the time rate of change of the expansion stress value on the surface of the sodium-ion battery is less than or equal to the stress threshold, then the sodium battery is determined to be in a low SOC safety wake-up state, no warning signal is generated, and the initial wake-up current is continuously applied and parameters are collected. If the time rate of change of the expansion stress value on the surface of the sodium-ion battery is greater than the stress threshold, and the state of charge (SOC) of the sodium-ion battery is higher than or equal to the safety reconfiguration threshold, it is determined to be an instantaneous stress fluctuation. No warning signal is generated, only abnormal data is recorded and continuously monitored. If the sodium-ion battery's state of charge (SOC) is lower than the preset safety reconfiguration threshold and the time rate of change of the expansion stress value on the sodium-ion battery surface is greater than the preset stress threshold, then the battery is immediately determined to have an abnormal gas production and expansion trend, and a gas production and expansion warning signal is generated. The state of charge (SOC) of the sodium-ion battery is calculated by combining real-time data of the sodium-ion battery terminal voltage and loop current with the coulomb method. The calculation frequency is consistent with the calculation frequency of the time change rate of the expansion stress value on the sodium-ion battery surface, ensuring the synchronization between the SOC of the sodium-ion battery and the expansion stress value on the sodium-ion battery surface. The safety reconstruction threshold is preset based on the electrode material, electrolyte characteristics and safe operating range of the sodium-ion battery, and is usually set to 10%-20% (which can be flexibly adjusted according to the specific battery model). The safety reconstruction threshold is used to define the safe range of reconstruction of the active materials inside the battery. When the state of charge (SOC) of the sodium-ion battery is lower than the safety reconstruction threshold, the stability of the internal structure of the battery decreases and the risk of gas production and expansion is likely to occur. The preset stress threshold is set in advance based on the shell material, structural strength and safe deformation range of the sodium-ion battery. It is usually set to 10-30με / s (which can be adjusted according to the specific battery size and strain gauge placement). The preset stress threshold is used to identify abnormal changes in expansion stress. When the time change rate of the expansion stress value on the surface of the sodium-ion battery exceeds the preset stress threshold, it indicates that the gas production rate inside the sodium-ion battery is accelerating, which poses a safety hazard of bulging, leakage or even fire. Charging circuit switching and repair charging module: Based on the gas expansion warning signal, the current initial wake-up current is cut off, and the intermittent micro-current pulse repair circuit is switched to charge until the time change rate of the expansion stress value on the sodium-ion battery surface drops below the preset stress threshold, and the charging circuit is reconnected.

[0026] In the charging circuit switching and repair charging module, based on the gas expansion warning signal, the current initial wake-up current is cut off, and the charging process is switched to the intermittent micro-current pulse repair circuit for charging. Based on the generated gas expansion warning signal, an emergency power-off command is immediately triggered to control the electronic switch in the wake-up charging circuit to quickly disconnect and cut off the currently applied initial wake-up current. The power-off response time does not exceed 10ms, so as to avoid the continuous application of the initial wake-up sodium current, which will aggravate the gas expansion inside the battery and prevent damage to the battery structure. In the charging circuit switching and repair charging module, the specific process of switching to the intermittent micro-current pulse repair circuit for charging is as follows: After the initial wake-up current is cut off, the switch is activated to switch the charging circuit from the wake-up charging circuit to the intermittent micro-current pulse repair circuit. This ensures that there is no instantaneous current surge or short-circuit risk during the switching process of the intermittent micro-current pulse repair circuit. After the switching is completed, a switching success signal is synchronously fed back to the display module so that staff can confirm the circuit status. The intermittent microcurrent pulse repair circuit and the wake-up charging circuit share the positive and negative terminal interfaces of the battery, and no manual intervention is required during the switching process, realizing fully automated control; After switching to the intermittent microcurrent pulse repair circuit, the repair charging mode is activated, and intermittent microcurrent pulses are applied for charging; The parameters of the intermittent microcurrent pulse in the intermittent microcurrent pulse repair circuit are preset according to the degree of deactivation of the sodium-ion battery and the current SOC value. The pulse current size is 0.005C-0.01C (C is the rated capacity of the sodium battery), the pulse width is 100-500ms, and the pulse interval is 1-3s. This invention does not limit these parameters. In the charging circuit switching and repair charging module, the specific process of reconnecting the charging circuit until the time change rate of the expansion stress value on the sodium-ion battery surface drops below the preset stress threshold is as follows: The time change rate of the expansion stress value on the surface of the sodium-ion battery is compared with the preset stress threshold. If the time change rate of the expansion stress value on the surface of the sodium-ion battery is still greater than or equal to the preset stress threshold, the intermittent microcurrent pulse repair charging circuit state is maintained until the time change rate of the expansion stress value on the surface of the sodium-ion battery is lower than the preset stress threshold for three consecutive times (with an interval of 1 second). It is determined that the gas expansion trend of the sodium battery has been effectively suppressed and the internal structure has become stable.

[0027] At this time, the switch is activated, disconnecting the intermittent micro-current pulse repair circuit and reconnecting the charging circuit. After the charging circuit is started, it uses constant current and constant voltage mode for regular charging. Example 2 like Figure 2 As shown, based on the specific implementation process of Example 1, the present invention provides a pre-warning current cutoff method for high-capacity sodium-ion batteries, comprising: Step S10: Obtain the initial terminal voltage of the sodium-ion battery, compare the initial terminal voltage of the sodium-ion battery with the preset extremely low voltage threshold, and determine whether the sodium-ion battery has entered the 0V wake-up charging mode. Step S20: If the sodium-ion battery enters the 0V wake-up charging mode, apply an initial wake-up current to the sodium-ion battery and collect the expansion stress value on the surface of the sodium-ion battery. Step S30: Calculate the rate of change of the expansion stress value on the surface of the sodium-ion battery over time; Step S40: When the state of charge (SOC) of the sodium-ion battery is lower than the preset safety reconfiguration threshold, and the time change rate of the expansion stress value on the surface of the sodium-ion battery is greater than the preset stress threshold, a gas production expansion warning signal is generated. Step S50: Based on the gas expansion warning signal, cut off the current initial wake-up current and switch to the intermittent microcurrent pulse repair circuit for charging until the time change rate of the expansion stress value on the sodium-ion battery surface drops below the preset stress threshold, and then reconnect the charging circuit.

[0028] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A warning-type current cut-off cover for high-capacity sodium-ion batteries, characterized in that: include: 0V wake-up charging mode determination module: acquires the initial terminal voltage of the sodium-ion battery, compares the initial terminal voltage of the sodium-ion battery with the preset extremely low voltage threshold, and determines whether the sodium-ion battery has entered the 0V wake-up charging mode. Expansion stress acquisition module: If the sodium-ion battery enters the 0V wake-up charging mode, an initial wake-up current is applied to the sodium-ion battery, and the expansion stress value on the surface of the sodium-ion battery is acquired. Expansion stress time change rate calculation module: Calculates the time change rate of expansion stress value on the surface of sodium-ion battery; Gas production expansion warning signal generation module: When the state of charge (SOC) of the sodium-ion battery is lower than the preset safety reconfiguration threshold, and the time change rate of the expansion stress value on the surface of the sodium-ion battery is greater than the preset stress threshold, a gas production expansion warning signal is generated. Charging circuit switching and repair charging module: Based on the gas expansion warning signal, the current initial wake-up current is cut off, and the intermittent micro-current pulse repair circuit is switched to charge until the time change rate of the expansion stress value on the sodium-ion battery surface drops below the preset stress threshold, and the charging circuit is reconnected.

2. The warning-type current cut-off cover for a high-capacity sodium-ion battery according to claim 1, characterized in that, The specific process for obtaining the initial terminal voltage of the sodium-ion battery is as follows: When the sodium-ion battery is at rest, the terminal voltage of the positive and negative terminals of the sodium-ion battery is collected to obtain the initial terminal voltage of the sodium-ion battery.

3. A warning-type current cut-off cover for a high-capacity sodium-ion battery according to claim 1, characterized in that, The specific process for determining whether a sodium-ion battery has entered the 0V wake-up charging mode is as follows: The initial terminal voltage of the sodium-ion battery is compared with a preset extremely low voltage threshold. If the initial terminal voltage of the sodium-ion battery is greater than or equal to the preset extremely low voltage threshold, the sodium-ion battery is determined to be in a normal low voltage state. If the initial terminal voltage of the sodium-ion battery is less than the preset extremely low voltage threshold, it is determined that the sodium-ion battery has entered the 0V wake-up charging mode.

4. A warning-type current cut-off cover for a high-capacity sodium-ion battery according to claim 1, characterized in that, The specific process of applying the initial wake-up current to the sodium-ion battery is as follows: After determining that the sodium-ion battery has entered the 0V wake-up charging mode, the wake-up charging circuit is switched, and the wake-up charging circuit is connected to the positive and negative terminals of the sodium-ion battery. The initial wake-up current adopts constant current mode, and the magnitude of the initial wake-up current is 0.01C-0.05C, where C is the rated capacity of the sodium battery.

5. A warning-type current cut-off cover for a high-capacity sodium-ion battery according to claim 1, characterized in that, The specific process for collecting the expansion stress value on the surface of the sodium-ion battery is as follows: High-precision strain gauges are uniformly attached to the upper surface, lower surface, and middle of the side of the sodium-ion battery to collect expansion stress values.

6. A warning-type current cut-off cover for a high-capacity sodium-ion battery according to claim 1, characterized in that, The specific process for calculating the time-varying rate of change of the expansion stress value on the surface of the sodium-ion battery is as follows: The expansion stress values ​​on the surface of sodium-ion batteries and the corresponding acquisition timestamps for the expansion stress values ​​on the surface of each group of sodium-ion batteries were obtained. The expansion stress values ​​on the surface of sodium-ion batteries acquired at two consecutive adjacent timestamps were selected and denoted as follows: Expansion stress value and Expansion stress value ,in Calculate the time interval ; through formula The time-varying rate of change of the expansion stress value on the surface of the sodium-ion battery was calculated. .

7. A warning-type current cut-off cover for a high-capacity sodium-ion battery according to claim 1, characterized in that, The specific process for generating the gas production expansion early warning signal is as follows: The system acquires the state of charge (SOC) value of the sodium-ion battery and the time rate of change of the expansion stress value on the surface of the sodium-ion battery. If the SOC value of the sodium-ion battery is lower than the preset safety reconfiguration threshold and the time rate of change of the expansion stress value on the surface of the sodium-ion battery is greater than the preset stress threshold, a gas production expansion warning signal is generated.

8. A warning-type current cut-off cover for a high-capacity sodium-ion battery according to claim 1, characterized in that, The specific process of switching to the intermittent microcurrent pulse repair circuit for charging is as follows: Based on the gas expansion warning signal, the electronic switch in the wake-up charging circuit is quickly disconnected, cutting off the currently applied initial wake-up current. After the initial wake-up current is cut off, the switching switch is activated, switching the charging circuit from the wake-up charging circuit to the intermittent micro-current pulse repair circuit.

9. A warning-type current cut-off cover for a high-capacity sodium-ion battery according to claim 8, characterized in that, The intermittent microcurrent pulse repair circuit is specifically as follows: The intermittent microcurrent pulse repair circuit and the wake-up charging circuit share the positive and negative terminal interfaces of the battery. The pulse current of the intermittent microcurrent pulse repair circuit is 0.005C-0.01C, where C is the rated capacity of the sodium battery.

10. A warning-type current cut-off cover for a high-capacity sodium-ion battery according to claim 1, characterized in that, The specific process of reconnecting the charging circuit is as follows: The time change rate of the expansion stress value on the surface of the sodium-ion battery is compared with the preset stress threshold. If the time change rate of the expansion stress value on the surface of the sodium-ion battery is still greater than or equal to the preset stress threshold, the intermittent microcurrent pulse repair charging circuit state is maintained. If the time change rate of the expansion stress value on the surface of the sodium-ion battery is lower than the preset stress threshold for three consecutive times, it is determined that the gas expansion trend of the sodium battery has been suppressed. The switching switch is activated, the intermittent micro-current pulse repair circuit is disconnected, and the charging circuit is reconnected.

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