Energy storage battery system and battery cell lithium precipitation repair method thereof

Abstract

The invention provides an energy storage battery system cell lithium precipitation repair method, which comprises the following steps of: acquiring battery parameters of a battery PACK in a charging process in real time, and judging whether a lithium precipitation risk exists or not based on the battery parameters; if the lithium precipitation risk exists, judging whether the voltage of the battery PACK reaches a preset voltage value V2 or above after the charging process is finished and the battery current is reduced to zero; if yes, executing pulse discharge operation: sending a pulse discharge request to an external communication power supply according to the specification of the battery cell, so as to enable the battery PACK to perform pulse discharge; normal charging and discharging are recovered after pulse discharging is finished; if the absolute value of the change slope of the battery cell voltage does not exceed the first threshold value K1 and the impedance of the battery PACK does not exceed the second threshold value Z1, it is judged that lithium precipitation repair is completed. According to the invention, through closed-loop control of real-time monitoring of charging parameters and linkage of pulse discharge, lithium precipitation products such as lithium dendrites are removed through pulse discharge operation, the lithium precipitation phenomenon is repaired, and the service life of the battery is prolonged.

Description

Technical Field

[0001] The present invention belongs to the technical field of energy storage systems, and in particular relates to an energy storage battery system and a method for repairing lithium deposition in its battery cells. Background Art

[0002] With the rapid development of new energy technologies, lithium-ion batteries are widely used in electric vehicles, energy storage systems, and other fields. However, lithium-ion batteries are highly susceptible to lithium plating during use. Lithium plating at the negative electrode forms lithium dendrites, which can lead to capacity degradation, increased internal resistance, and even a short circuit between the positive and negative electrodes. Over time, this can lead to the risk of battery fires, resulting in personal and property damage, and seriously affecting battery performance and safety. Therefore, battery management systems are crucial for accurately detecting the status or risk of lithium plating and for automatically remediating this plating.

[0003] In the related art, there are methods of using a coating diaphragm to inhibit the growth of lithium dendrites or using electromagnetic shock waves to remove lithium dendrites to solve the problems caused by lithium dendrites. However, whether it is a method of using a coating diaphragm or a method of using electromagnetic shock waves to remove lithium dendrites, it is impossible to quickly and efficiently remove lithium dendrites from lithium batteries. In addition, existing battery lithium deposition detection methods usually rely on a single data source or analysis unit for judgment. This method is easily affected by factors such as data collection errors and environmental interference, resulting in insufficient reliability of the detection results, affecting the safety and cycle life of the battery. Summary of the Invention

[0004] The present invention aims to solve one of the technical problems in the related art at least to a certain extent.

[0005] According to an embodiment of the present disclosure, a method for repairing lithium deposition in a battery cell of an energy storage battery system is provided, comprising the following steps:

[0006] Real-time detection of battery parameters of the battery pack during charging, and determination of whether there is a risk of lithium plating based on the battery parameters;

[0007] If there is a risk of lithium plating, after the charging process is completed and the battery current drops to zero, it is determined whether the voltage of the battery PACK reaches or exceeds a preset voltage value V2;

[0008] If the voltage of the battery pack reaches a preset voltage value or above, a pulse discharge operation is performed: a pulse discharge request is sent to an external communication power supply according to the battery cell specifications, so that the battery pack performs pulse discharge with a discharge current I2 and a discharge time t1;

[0009] After the pulse discharge is completed, the normal charge and discharge of the battery pack is resumed, and the cell voltage and the impedance of the battery pack during the charge and discharge process are detected in real time;

[0010] If the absolute value of the change slope of the cell voltage does not exceed the first threshold value K1, and the impedance does not exceed the second threshold value Z1, it is determined that the lithium plating repair is completed.

[0011] The above technical solution has the following advantages or beneficial effects: through real-time monitoring of charging parameters and closed-loop control linked with pulse discharge, when there is a risk of lithium plating, pulse discharge operation is used to remove lithium plating products such as lithium dendrites, repair the lithium plating phenomenon, ensure the safe and stable operation of the battery, extend the battery life, and avoid battery safety hazards caused by manual intervention delays.

[0012] According to an embodiment of the present disclosure, the energy storage battery system cell lithium deposition repair method further includes:

[0013] If the voltage of the battery PACK is below the preset voltage value, the external communication power supply is controlled to continue charging the battery PACK until the voltage of the battery PACK reaches above the preset voltage value and the battery current drops to zero, and then the pulse discharge operation is performed again.

[0014] The above technical solution has the following advantages or beneficial effects: the battery PACK is charged to a safe voltage and then pulse discharged, thereby ensuring that the battery PACK is in a controllable state, improving the effectiveness and safety of the pulse discharge operation, and enhancing the repair effect.

[0015] According to an embodiment of the present disclosure, the energy storage battery system cell lithium deposition repair method further includes:

[0016] If the absolute value of the change slope of the cell voltage exceeds the first threshold K1 or the impedance is greater than the second threshold Z1, the pulse discharge operation is performed again after the charge and discharge process is completed and the battery current drops to zero.

[0017] The above technical solution has the following advantages or beneficial effects: according to the feedback results of the battery cell voltage slope and impedance, the secondary pulse discharge is dynamically triggered to ensure that the lithium plating repair is completely completed, effectively protecting the performance and safety of the battery pack.

[0018] According to an embodiment of the present disclosure, the battery parameters include one or more of charging current, cell voltage, and cell temperature;

[0019] Determining whether there is a risk of lithium plating based on the battery parameters includes the following steps:

[0020] If the charging current exceeds the preset current threshold I1, or any cell voltage exceeds the preset voltage threshold V1, or any cell temperature is lower than the preset temperature threshold T1, it is determined that there is a lithium plating risk; otherwise, it is determined that there is no lithium plating risk.

[0021] The above technical solution has the following advantages or beneficial effects: considering different working conditions, integrating multiple key battery parameters to judge the risk of lithium plating, improving the accuracy and timeliness of the judgment, and providing a more reliable triggering basis for subsequent pulse discharge repair operations.

[0022] According to an embodiment of the present disclosure, the preset current threshold I1 is an overcurrent protection value of the battery PACK.

[0023] The above technical solution has the following advantages or beneficial effects: effectively solving the problem of overcurrent charging causing lithium deposition at the negative electrode of the battery pack, improving battery life, and reducing the risk of battery fire.

[0024] According to an embodiment of the present disclosure, the preset voltage threshold V1 is an overvoltage protection value of the battery PACK, and / or the preset temperature threshold T1 is a charging low-temperature protection value of the battery PACK.

[0025] The above technical solution has the following advantages or beneficial effects: it effectively solves the lithium deposition phenomenon at the negative electrode of the battery pack caused by low-temperature charging and charging overvoltage, thereby improving battery life and reducing the risk of battery fire.

[0026] According to an embodiment of the present disclosure, the discharge current I2 satisfies: 0.1C≤I2≤1C, where C is the rated capacity of the battery cell; and the discharge time t1 satisfies: 10ms≤t1≤5s.

[0027] The above technical solution has the following advantages or beneficial effects: the current and time of the pulse discharge are reasonably set to ensure that lithium dendrites and other lithium precipitation products can be effectively removed without causing damage to the battery due to excessive discharge.

[0028] Another aspect of the present application further provides an energy storage battery system, comprising:

[0029] External communication power supply;

[0030] The battery PACK includes a battery management system BMS and a battery cell. The battery cell is electrically connected to the external communication power supply through a main circuit so that the external communication power supply can charge and discharge the battery cell. The battery management system BMS includes:

[0031] A sampling module, electrically connected to the main circuit, for collecting battery parameters during the charging and discharging process in real time;

[0032] A communication module, communicatively connected to the external communication power supply;

[0033] A controller is connected to the communication module and the sampling module, and the controller includes a processor and a memory communicatively connected to the processor; wherein the memory stores instructions executed by the processor, and the instructions are executed by the processor so that the processor can execute the battery cell lithium plating repair method described in any of the above technical solutions.

[0034] The above technical solution has the following advantages or beneficial effects: by constructing an energy storage battery system including an external communication power supply, a battery PACK and its internal BMS, real-time monitoring of the risk of lithium plating in the battery cell and automatic repair of lithium plating are achieved, thereby improving the overall performance and reliability of the battery system and enhancing its market competitiveness.

[0035] In some embodiments of the present application, the battery management system may include a driving module, and the driving module is used to drive the main circuit and the pre-charging circuit to be turned on or off.

[0036] The above technical solution has the following advantages or beneficial effects: by setting up a drive module, the battery management system can accurately and timely control the conduction or disconnection of the main circuit and the pre-charge circuit, thereby improving the safety and reliability of the battery system when switching between different working states.

[0037] According to an embodiment of the present disclosure, the main circuit includes a positive switch and a negative switch, and the pre-charging circuit includes a branch formed by connecting the pre-charging resistor and the pre-charging switch in series, and the branch is connected in parallel with one of the positive switch and the negative switch of the main circuit.

[0038] The above technical solution has the following advantages or beneficial effects: the above-mentioned battery cell lithium plating repair method can be adapted to the circuit architecture in different battery PACKs, can flexibly adapt to different circuit design requirements, reduces the design complexity caused by differences in circuit architecture, and enables the battery system to be integrated into different application scenarios more quickly. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0040] Figure 1 This is a flow chart of the lithium plating repair logic of the energy storage battery system according to one embodiment of the present application;

[0041] Figure 2 This is a circuit architecture diagram of an energy storage battery system according to one embodiment of the present application;

[0042] Figure 3 This is a circuit architecture diagram of an energy storage battery system according to another embodiment of the present application;

[0043] Figure 4 This is a flow chart of the control logic using PCS as the external communication power supply according to an embodiment of the present application.

[0044] In the above figures, there are an external communication power supply 1; a battery PACK 2; a DCDC module 21; a drive module 22; a battery cell 23; a communication module 24; a sampling module 25; and a controller 26. DETAILED DESCRIPTION

[0045] The following will provide a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0046] In the description of the present invention, it should be understood that the terms "center", "lateral", "longitudinal", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0047] The terms "first," "second," and "third" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly specifying the quantity of the technical features indicated. Therefore, a feature specified as "first," "second," or "third" may explicitly or implicitly include one or more of the features.

[0048] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood broadly. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to direct connections, indirect connections via an intermediate medium, or internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0049] The present invention provides a method for repairing lithium deposition in battery cells of an energy storage battery system. When there is a risk of lithium deposition in a battery pack, a pulse current of a specific direction and magnitude is used to dissolve lithium dendrites, thereby repairing the deposited metallic lithium in real time and improving the safety and cycle life of the battery.

[0050] refer to Figure 1, a method for repairing lithium deposition in a battery cell of an energy storage battery system, comprising the following steps:

[0051] Step S1: Real-time detection of battery parameters of the battery pack during charging, and determination of whether there is a risk of lithium plating based on the battery parameters;

[0052] Step S2: If there is a risk of lithium plating, after the charging process is completed and the battery current drops to zero, determine whether the voltage of the battery pack reaches or exceeds a preset voltage value V2;

[0053] Step S3: If the voltage of the battery pack reaches or exceeds the preset voltage value, a pulse discharge operation is performed: a pulse discharge request is sent to the external communication power supply according to the battery cell specifications, so that the battery pack performs pulse discharge with a discharge current I2 and a discharge time t1;

[0054] Step S3: After the pulse discharge is completed, the normal charge and discharge of the battery pack is resumed, and the cell voltage and the impedance of the battery pack during the charge and discharge process are detected in real time;

[0055] Step S5: If the absolute value of the slope of the change of the cell voltage does not exceed the first threshold value K1, and the impedance does not exceed the second threshold value Z1, it is determined that the lithium deposition repair is completed.

[0056] In this embodiment, by real-time monitoring of charging parameters and closed-loop control linked to pulse discharge, when there is a risk of lithium deposition, a pulse discharge operation is performed according to the voltage conditions after charging is completed, and the pulse current is used to remove lithium deposition products such as lithium dendrites, repair the lithium deposition phenomenon, ensure the safe and stable operation of the battery, extend the battery life, and avoid battery safety hazards caused by manual intervention delays.

[0057] When normal charging and discharging is resumed after pulse discharge, the voltage change slope and impedance of the battery cell are continued to be monitored to determine whether the repair is complete, thus forming a complete lithium plating repair process that can timely detect and deal with lithium plating risks, thereby improving the safety, stability and service life of the battery.

[0058] In this embodiment, the battery parameters may include one or more of charging current, battery cell voltage, and battery cell temperature.

[0059] Specifically, judging whether there is a risk of lithium plating based on battery parameters includes the following steps:

[0060] If the charging current exceeds the preset current threshold I1, or the voltage of any battery cell exceeds the preset voltage threshold V1, or the temperature of any battery cell is lower than the preset temperature threshold T1, then it is determined that there is a risk of lithium plating. Otherwise, it is determined that there is no risk of lithium plating.

[0061] In this embodiment, various situations in which lithium plating risks exist are taken into consideration, and multiple key battery parameters during the charging process are comprehensively considered to judge the lithium plating risk, thereby improving the accuracy and timeliness of the lithium plating risk judgment and providing a more reliable triggering basis for subsequent pulse discharge repair operations.

[0062] The preset current threshold I1 is the overcurrent protection value of the battery pack, the preset voltage threshold V1 is the overvoltage protection value of the battery pack, and the preset temperature threshold T1 is the low-temperature protection value of the battery pack during charging.

[0063] The above embodiment can effectively solve the problem of lithium plating at the negative electrode of the battery pack caused by overcurrent charging, low-temperature charging, and overvoltage charging, thereby improving battery life and reducing the risk of battery fire.

[0064] It's understandable that batteries have a maximum charging current, a minimum charging temperature, and a maximum charging voltage limit. Exceeding the maximum charging current is considered overcurrent charging, and the maximum charging current is the overcurrent protection value. Charging is prohibited below the minimum charging temperature, and this value is the low-temperature protection value. Continued charging is hazardous when the voltage exceeds the maximum charging voltage limit, and the maximum charging voltage limit is the overvoltage protection value.

[0065] Furthermore, the energy storage battery system core lithium plating repair method also includes:

[0066] If the voltage of the battery PACK is below the preset voltage value, the external communication power supply is controlled to continue charging the battery PACK until the voltage of the battery PACK reaches above the preset voltage value and the battery current drops to zero, and then the pulse discharge operation is performed again.

[0067] In this embodiment, the battery pack is charged to a safe voltage before pulse discharge, ensuring that the battery pack is in a controllable state. This improves the effectiveness and safety of the pulse discharge operation, enhances the repair effect, and avoids irreversible damage caused by undervoltage discharge.

[0068] In the above embodiment, there may be a situation where lithium deposition is not completely repaired after a pulse discharge. If it cannot be discovered and processed again in time, the battery performance will be affected.

[0069] In order to complete the lithium deposition repair, in some embodiments of the present application, the energy storage battery system cell lithium deposition repair method further includes:

[0070] If the absolute value of the slope of change of the battery cell voltage exceeds the first threshold K1 or the impedance is greater than the second threshold Z1, after the charge and discharge process is completed and the battery current drops to zero, the pulse discharge operation is performed again until the lithium plating repair is completed.

[0071] In this embodiment, secondary pulse discharge is dynamically triggered based on the feedback results of the battery cell voltage slope and impedance, thereby realizing dynamic monitoring and repeated correction of the repair process, ensuring that the lithium plating repair is completely completed, effectively protecting the performance and safety of the battery pack, and enhancing the reliability and flexibility of the repair method.

[0072] In some embodiments of the present application, the discharge current I2 satisfies: 0.1C≤I2≤1C, where C is the rated capacity of the battery cell; and the discharge time t1 satisfies: 10ms≤t1≤5s. In other words, the discharge rate is 0.1-1.

[0073] The current and time of pulse discharge are reasonably set to ensure that lithium dendrites and other lithium precipitation products can be effectively removed without causing damage to the battery due to excessive discharge.

[0074] Another aspect of the present application provides an energy storage battery system for implementing the battery cell lithium plating repair method described in any of the above technical solutions, which includes an external power supply and a battery pack. The external communication power supply 1 is connected to the battery pack 2 for charging and discharging the battery pack 2.

[0075] The external communication power supply 1 can be a DC power supply with communication capabilities or a PCS power conversion system with energy storage. Using a DC power supply with communication capabilities or a PCS power conversion system with energy storage as the external communication power supply 1 can meet the needs of all application scenarios.

[0076] A DC power supply with communication capabilities is selected as external communication power supply 1, providing stable voltage output. Furthermore, DC power supplies typically support a wide input voltage range, adapting to varying grid conditions. A PCS energy storage power conversion system is selected as external communication power supply 1, enabling bidirectional conversion between DC and AC, enabling both charging and discharging, and increasing system flexibility.

[0077] refer to Figure 2 、 Figure 3 The battery PACK2 may include a battery management system BMS and a battery cell 23 connected to the battery management system BMS. The battery cell 23 is used to store electricity, and the battery management system BMS is used to monitor and protect the battery cell 23 and communicate with the external communication power supply 1.

[0078] Specifically, the battery cell 23 is electrically connected to the external communication power supply 1 through the main circuit, so that the external communication power supply 1 charges and discharges the battery cell 23 through the main circuit.

[0079] The main circuit includes a positive switch K2 and a negative switch K3. The positive switch K2 is connected to the positive terminal of the battery cell, and the negative switch K3 is connected to the negative terminal of the battery cell. The positive switch K2, the negative switch K3, and the pre-charge switch K1 can be relays.

[0080] The main circuit is provided with a pre-charge circuit, which effectively protects the battery cells 23, the external communication power supply 1, and the switching components, preventing damage due to overcurrent and extending their service life.

[0081] The pre-charge circuit includes a branch formed by a pre-charge resistor R1 and a pre-charge switch K1 connected in series, and the branch is connected in parallel with one of the positive switch and the negative switch of the main circuit.

[0082] That is, reference Figure 2 , the branch can be connected in parallel with the positive switch K2. Figure 3 , the branch can also be connected in parallel with the negative switch K3. Among them, the positive switch K2 and the negative switch K3 are defined as follows: the one connected in parallel with the branch is a parallel switch, and the other is a non-parallel switch.

[0083] It is understood that different circuit architectures in battery PACK 2 can be selected based on actual application scenarios and design requirements. For example, a circuit architecture in which the pre-charge resistor R1 is connected in parallel to the positive switch K2 may be more suitable for scenarios requiring strict control of the positive current, while a circuit architecture in which the pre-charge resistor R1 is connected in parallel to the negative switch K3 may be more suitable for simplifying the design of the negative circuit.

[0084] In this embodiment, the cooperation between the pre-charge resistor R1 and the pre-charge switch K1 can limit the current at the initial charging stage, avoid instantaneous large current shocks caused by voltage differences, and improve the safety and reliability of the charging process.

[0085] The above-mentioned battery cell lithium plating repair method can be adapted to the circuit architecture of different battery packs, can flexibly adapt to different circuit design requirements, reduce the design complexity caused by differences in circuit architecture, and enable the battery system to be integrated into different application scenarios more quickly.

[0086] For further reference, Figure 2 、 Figure 3 The battery management system (BMS) may include a sampling module 25. The sampling module 25 is connected to the battery pack 2 and is used to collect battery parameters during the charging and discharging process in real time. The battery parameters include at least the voltage, charging current, discharging current, cell temperature, and cell voltage of the battery pack 2.

[0087] The sampling module 25 may include an AFE (analog front end), which in the BMS specifically refers to a battery sampling chip for collecting battery voltage, current, and temperature, etc. The sampling module 25 may also include a separate sampling circuit.

[0088] For further reference, Figure 2 、 Figure 3 The battery management system BMS may include a communication module 24, which is communicatively connected to the external communication power supply 1. The communication module 24 enables two-way communication between the battery pack 2 and the external communication power supply 1.

[0089] The communication module 24 may be a CAN communication module 24 or a 485 communication module 24 . This application does not limit the communication method of the communication module 24 .

[0090] The battery management system BMS may include a controller 26 , which is connected to the communication module 24 and the sampling module 25 .

[0091] The controller 26 includes a processor and a memory in communication with the processor; the memory stores instructions executable by the processor, which are executed by the processor to enable the processor to perform the battery cell lithium plating repair method described in any of the above technical solutions. The controller 26 may be an MCU.

[0092] In this embodiment, by constructing an energy storage battery system including an external communication power supply, a battery PACK and its internal BMS, real-time monitoring and automatic repair functions of lithium plating in the battery cell are achieved, thereby improving the overall performance and reliability of the battery system and enhancing its market competitiveness.

[0093] Specifically, the controller 26 is configured to:

[0094] During the charging process of the battery PACK, the battery parameters collected by the sampling module 25 are received and judged whether there is a risk of lithium plating;

[0095] If there is a risk of lithium plating, after the charging process is completed and the battery current drops to zero, it is determined whether the voltage of the battery pack reaches or exceeds the preset voltage value V2;

[0096] If the voltage of the battery pack reaches above the preset voltage value, a pulse discharge operation is performed;

[0097] After the pulse discharge is completed, the normal charge and discharge of the battery pack is resumed, and the cell voltage and the impedance of the battery pack during the charge and discharge process are obtained in real time;

[0098] If the absolute value of the change slope of the battery cell voltage is lower than the first threshold K1, and the impedance is lower than the second threshold Z1, it is determined that the lithium plating repair is completed.

[0099] The battery management system BMS may include a DCDC module 21 , which is connected to the battery cells 23 and the external communication power supply 1 , and is used to supply power to the battery management system BMS.

[0100] The above configuration enables the DCDC module 21 to draw power from both the external communication power supply 1 and the battery cell 23 . The dual power supply mode improves the flexibility and reliability of the system.

[0101] During the operation of the battery management system BMS, when the external communication power supply 1 is available, it can be powered by the external communication power supply 1; when the external communication power supply 1 is unavailable or fails, the battery cell 23 used to store electricity can be used as a backup power supply to ensure the continuous operation of the BMS.

[0102] Of course, in some other embodiments, when the battery PACK2 is in a low voltage state and cannot be started, the DCDC module 21 is electrically connected to the external communication power supply 1 and can charge the battery PACK2 for remedial purposes.

[0103] In this embodiment, by setting a DCDC module 21 in the battery management system BMS, when the battery PACK2 is in a low voltage and cannot be started state, the DCDC module 21 is connected to the external communication power supply 1 to directly and quickly charge the battery PACK2, ensuring that the battery management system BMS can start and operate normally, thereby improving the reliability of the energy storage battery system.

[0104] In some embodiments of the present application, the battery management system may include a driving module, and the driving module is used to drive the main circuit and the pre-charging circuit to be turned on or off.

[0105] Specifically, the input of the driver module is connected to the output of the controller 26, and the output of the driver module is connected to the controlled terminals of the positive switch K2, the negative switch K3, and the pre-charge switch K1. The driver module drives the positive switch K2, the negative switch K3, and the pre-charge switch K1 to open or close according to the drive instructions issued by the controller 26.

[0106] In this embodiment, by providing a driving module, the battery management system can accurately and timely control the conduction or disconnection of the main circuit and the pre-charging circuit, thereby improving the safety and reliability of the battery system when switching between different working states.

[0107] refer to Figure 4 , taking the external communication power supply 1 as PCS as an example, the control logic of the energy storage system is described in detail.

[0108] After the energy storage system is powered on, the battery management system BMS performs a self-check. After the self-check passes, the non-parallel switches of the main circuit are closed in sequence ( Figure 1 It is the negative switch K3, Figure 2 When the positive switch K2) and the pre-charge switch K1 are connected, the pre-charge function is performed. After the pre-charge is completed, the parallel switch ( Figure 1 It is the positive switch K2, Figure 2 Then, the battery management system BMS uploads the charge and discharge current limit value, and the PCS charges and discharges according to the charge and discharge current limit value, and then decides to charge and discharge the battery PACK according to the load status, grid status, and working mode; at the same time, the battery management system BMS monitors the battery parameters.

[0109] When the battery pack is charging, the battery pack current (charging current), cell voltage, and cell temperature are monitored throughout the entire process. When the charging current is greater than the preset current threshold I1, the cell voltage is greater than the preset voltage threshold V1, or the cell temperature is lower than the preset temperature threshold T1, the battery management system (BMS) initiates a pulse discharge procedure. After detecting that charging has stopped, the battery current has dropped to 0, and the battery pack voltage (battery voltage) has reached or exceeded the preset voltage value V2, the battery management system (BMS) requests a pulse discharge from the PCS, with a discharge current of I2 and a discharge time of t1.

[0110] Among them, according to the requirements of the battery cell specification, I2 is between 0.1C and 1C, and t1 is between 10ms and 5s; if the battery voltage is lower than the preset voltage value V2 after charging stops, the battery management system BMS will apply to the PCS to continue charging until the battery voltage is greater than the preset voltage value V2 and the battery current drops to 0, and then pulse discharge is performed.

[0111] After the pulse discharge is completed, the battery PACK performs normal charge and discharge. During the charge and discharge process, the battery management system BMS detects the cell voltage of the battery PACK throughout the process. If the absolute value of the slope of the change of the cell voltage is greater than the first threshold K1 or the battery management system BMS detects through the automatic detection program that the impedance of the battery PACK is greater than the second threshold Z1, then after the battery is charged and discharged and the battery current drops to 0, the battery management system BMS will perform the pulse discharge operation again.

[0112] When the pulse discharge ends and the battery is in normal charge and discharge process, the absolute value of the slope of the change of the cell voltage does not exceed the first threshold K1, and the impedance of the battery PACK does not exceed the second threshold Z1, which means that the pulse current has dissolved the lithium dendrites. It is then determined that the lithium plating repair is completed, and the pulse discharge process ends at this time.

[0113] The present invention can automatically detect the risk of lithium plating, and when there is a risk of lithium plating, use a pulse current of a specific direction and magnitude to dissolve lithium dendrites, automatically repair the deposited metallic lithium, improve the safety and cycle life of the battery, and reduce the risk of battery fire.

[0114] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any other form. Any person skilled in the art may use the technical contents disclosed above to change or modify them into equivalent embodiments with equivalent changes for application in other fields. However, any simple modification, equivalent change and modification of the above embodiments made in accordance with the technical essence of the present invention without departing from the technical solution of the present invention shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A method for repairing lithium deposition in a battery cell of an energy storage battery system, characterized in that: The repair method comprises the following steps: Acquire battery parameters of the battery PAC K in real time during the charging process, and determine whether there is a risk of lithium plating based on the battery parameters; If there is a risk of lithium plating, after the charging process is completed and the battery current drops to zero, it is determined whether the voltage of the battery PAC K reaches or exceeds a preset voltage value V2; If the voltage of the battery PAC K reaches a preset voltage value or above, a pulse discharge operation is performed: a pulse discharge request is sent to an external communication power supply according to the battery cell specifications, so that the battery PAC K performs pulse discharge with a discharge current I2 and a discharge time t1; After the pulse discharge is completed, the normal charge and discharge of the battery PACK is restored, and the cell voltage and the impedance of the battery PACK during the charge and discharge process are obtained in real time; If the absolute value of the change slope of the cell voltage does not exceed the first threshold value K1, and the impedance does not exceed the second threshold value Z1, it is determined that the lithium plating repair is completed.

2. The method for repairing lithium deposition in a battery cell of an energy storage battery system according to claim 1, wherein: Also includes: If the voltage of the battery PAC K is below the preset voltage value, the external communication power supply is controlled to continue charging the battery PAC K until the voltage of the battery PAC K reaches above the preset voltage value and the battery current drops to zero, and the pulse discharge operation is performed again until the lithium plating repair is completed.

3. The method for repairing lithium deposition in a battery cell of an energy storage battery system according to claim 1, wherein: Also includes: If the absolute value of the change slope of the cell voltage exceeds the first threshold K1 or the impedance is greater than the second threshold Z1, the pulse discharge operation is performed again after the charge and discharge process is completed and the battery current drops to zero.

4. The method for repairing lithium deposition in a battery cell of an energy storage battery system according to claim 1, wherein: The battery parameters include one or more of charging current, battery cell voltage, and battery cell temperature; Determining whether there is a risk of lithium plating based on the battery parameters includes the following steps: If the charging current exceeds the preset current threshold I1, or any of the battery cell voltages exceeds the preset voltage threshold V1, or any of the battery cell temperatures is lower than the preset temperature threshold T1, it is determined that there is a risk of lithium plating; otherwise, it is determined that there is no risk of lithium plating.

5. The method for repairing lithium deposition in a battery cell of an energy storage battery system according to claim 4, characterized in that: The preset current threshold I1 is the overcurrent protection value of the battery PACK.

6. The method for repairing lithium deposition in a battery cell of an energy storage battery system according to claim 4, characterized in that: The preset voltage threshold V1 is an overvoltage protection value of the battery PACK, and / or the preset temperature threshold T1 is a charging low-temperature protection value of the battery PACK.

7. The method for repairing lithium deposition in a battery cell of an energy storage battery system according to claim 1, wherein: The discharge current I2 satisfies: 0.1C≤I2≤1C, where C is the rated capacity of the battery cell; and the discharge time t1 satisfies: 10ms≤t1≤5s.

8. An energy storage battery system, characterized in that: include: External communication power supply; The battery PAC K includes a battery management system BMS and battery cells. The battery cells are electrically connected to the external communication power supply through a main circuit so that the external communication power supply can charge and discharge the battery cells. The battery management system BMS includes: A sampling module, electrically connected to the main circuit, for collecting battery parameters during the charging and discharging process in real time; A communication module, communicatively connected to the external communication power supply; A controller is connected to the communication module and the sampling module, and the controller includes a processor and a memory communicatively connected to the processor; wherein the memory stores instructions executed by the processor, and the instructions are executed by the processor so that the processor can execute the battery cell lithium plating repair method according to any one of claims 1 to 7.

9. The energy storage battery system according to claim 8, characterized in that: The battery management system further includes: a driving module, wherein a pre-charging circuit is provided on the main circuit, and the driving module is used to drive the main circuit and the pre-charging circuit to be connected or disconnected.

10. The energy storage battery system according to claim 8 or 9, characterized in that: The main circuit includes a positive switch and a negative switch, and the pre-charge circuit includes a branch formed by connecting the pre-charge resistor and the pre-charge switch in series, and the branch is connected in parallel with one of the positive switch and the negative switch of the main circuit.

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