Electrochemical device management method, electrochemical device, battery module, and electric device

Abstract

The embodiment of the present application provides an electrochemical device management method, an electrochemical device and an electric equipment, including: performing first charge-discharge cycle on the electrochemical device by a charging current; performing intermittent charging operation on the electrochemical device, obtaining data related to the electrochemical device in the intermittent charging operation, determining lithium precipitation SOC of the electrochemical device based on the related data; and in response to the lithium precipitation SOC being less than or equal to an SOC threshold value, controlling at least one heating element to shunt the charging current and heat the electrochemical device. The embodiment of the present application can reduce the risk of lithium precipitation of the electrochemical device, the heat generated by the heating element enables the electrochemical device to be charged at a higher temperature, and can also alleviate the lithium precipitation of the electrochemical device, thereby improving the safety of the electrochemical device.

Description

Technical Field

[0001] This application relates to the field of electrochemical technology, and in particular to an electrochemical device management method, an electrochemical device, a battery module, and an electrical device. Background Technology

[0002] Lithium-ion batteries have many advantages, such as high energy density, long cycle life, high nominal voltage, low self-discharge rate, small size, and light weight, and are widely used in the consumer electronics field.

[0003] As lithium-ion batteries cycle or are stored, their lithium plating window gradually narrows. For example, lithium-ion batteries do not plating lithium when charged with the rated current at the beginning of the cycle, but as the cycle progresses, lithium plating will occur if the rated current is continued to be charged. Therefore, it is necessary to reduce the charging current in time when the risk of lithium plating is detected to ensure battery safety.

[0004] In related technologies, blind shaving is usually used when reducing the charging current, that is, reducing the current by a predetermined current value. However, this current reduction method is prone to under-shaving, and the electrochemical device still has the risk of lithium plating, which affects the safety of the electrochemical device and the user experience. Summary of the Invention

[0005] The purpose of this application is to provide an electrochemical device management method, an electrochemical device, a battery module, and an electrical device, in order to reduce the risk of lithium plating during the use of the electrochemical device and improve the safety of the electrochemical device. The specific technical solution is as follows:

[0006] A first aspect of this application provides a method for managing an electrochemical device, comprising performing a first charge-discharge cycle on the electrochemical device with a charging current; performing an intermittent charging operation on the electrochemical device, acquiring data related to the electrochemical device during the intermittent charging operation, determining the lithium plating state of the electrochemical device based on the related data; and controlling at least one heating element to shunt the charging current and heat the electrochemical device in response to the lithium plating state of the state being less than or equal to a state of the ...

[0007] The beneficial effects of the embodiments of this application are as follows: The embodiments of this application reduce the charging current of the electrochemical device by shunting the charging current through the heating element, which can reduce the risk of lithium plating. The heat generated by the heating element allows the electrochemical device to be charged at a higher temperature, which can also alleviate lithium plating in the electrochemical device and improve the safety of the electrochemical device.

[0008] In one embodiment of this application, the SOC threshold includes n SOC thresholds that gradually decrease from i equal to 1 to n. When i is 1 to n-1, the number of heating elements used for shunting the current corresponding to the i-th SOC threshold is i. The step of controlling at least one heating element to shun the charging current and heat the electrochemical device in response to the lithium plating SOC being less than or equal to the SOC threshold includes: controlling i heating elements to shun the charging current and heat the electrochemical device in response to the lithium plating SOC being less than or equal to the i-th SOC threshold. This embodiment of the application can control different numbers of heating elements to shun the charging current and heat the electrochemical device for different lithium plating SOCs of the determined electrochemical device, further preventing lithium plating and extending the service life of the electrochemical device.

[0009] In one embodiment of this application, the method further includes: controlling the electrochemical device to stop working in response to the lithium plating SOC being less than or equal to the nth SOC threshold; generating a prompt message that can prompt the user to replace the electrochemical device, thereby improving the user experience.

[0010] In one embodiment of this application, the heating element is disposed inside the electrochemical device and / or on the outer surface of the electrochemical device, thereby optimizing the arrangement of the heating element and enabling the heating element to heat the electrochemical device more effectively.

[0011] In one embodiment of this application, the heating element is made of at least one of nickel, nickel-aluminum alloy, copper, polyimide, silicone, or a positive temperature coefficient material; the impedance of the heating element ranges from 0.01Ω to 50Ω, and it has good heating performance.

[0012] In one embodiment of this application, the data related to the electrochemical device includes the state of charge (SOC) and internal resistance of the electrochemical device. The intermittent charging operation includes multiple charging periods and multiple interrupted periods. The step of acquiring the data related to the electrochemical device during the intermittent charging operation and determining the lithium plating SOC of the electrochemical device based on the related data includes, during the intermittent charging operation, acquiring the SOC and internal resistance of the electrochemical device during each of the multiple interrupted periods; obtaining a first curve based on the acquired multiple SOCs of the electrochemical device and the multiple internal resistances of the electrochemical device corresponding to the multiple SOCs, wherein the first curve is a mapping curve corresponding to the SOC and internal resistance of the electrochemical device; and determining the lithium plating SOC of the electrochemical device based on the first curve.

[0013] In one embodiment of this application, the step of determining the lithium plating SOC of the electrochemical device based on the first curve includes at least one of method 1 or method 2, wherein: method 1 includes: performing a first-order derivative on the first curve to obtain a second curve; and determining the SOC corresponding to the first point on the second curve where the slope is negative as the lithium plating SOC. Method 2 includes: performing a first-order derivative on the first curve to obtain a second curve; performing a second-order derivative on the second curve to obtain a third curve; and determining the SOC corresponding to the first point on the third curve where the ordinate is less than zero as the lithium plating SOC.

[0014] In one embodiment of this application, the intermittent charging operation includes multiple charging cycles, each charging cycle including a charging period and an intermittent period, during which the SOC of the electrochemical device increases by a unit magnitude.

[0015] In one embodiment of this application, the electrochemical device includes at least one of a lithium iron phosphate system electrochemical device, a lithium nickel cobalt manganese oxide system electrochemical device, or a lithium cobalt oxide system electrochemical device. Specifically, the electrochemical device is a lithium iron phosphate system electrochemical device, the unit amplitude ranges from 0.5% to 10%, and the duration of the intermittent period ranges from 1 second to 15 seconds; the electrochemical device is a lithium nickel cobalt manganese oxide system electrochemical device, the unit amplitude ranges from 0.5% to 10%, and the duration of the intermittent period ranges from 1 second to 30 seconds; or the electrochemical device is a lithium cobalt oxide system electrochemical device, the unit amplitude ranges from 0.5% to 10%, and the duration of the intermittent period ranges from 1 second to 30 seconds. This embodiment of the application more specifically performs intermittent charging operations on electrochemical devices of different systems, enabling more accurate determination of the lithium plating state of charge (SOC) for each system.

[0016] In one embodiment of this application, the intermittent charging device is specifically used for any one of the following a) to c): a) the electrochemical device is a lithium iron phosphate system electrochemical device, the electrochemical device is located at an ambient temperature of -10°C to 10°C, the unit amplitude ranges from 0.5% to 10%, and the duration of the intermittent period ranges from 5 seconds to 15 seconds; b) the electrochemical device is a lithium iron phosphate system electrochemical device, the electrochemical device is located at an ambient temperature of 10°C to 45°C, the unit amplitude ranges from 0.5% to 10%, and the duration of the intermittent period ranges from 1 second to 10 seconds; The duration of the intermittent period ranges from 10 to 30 seconds; the electrochemical device is a lithium nickel cobalt manganese oxide system electrochemical device, the electrochemical device is in an ambient temperature of 10°C to 45°C, the unit amplitude ranges from 0.5% to 10%, and the duration of the intermittent period ranges from 1 to 10 seconds; c) the electrochemical device is a lithium cobalt oxide system electrochemical device, the electrochemical device is in an ambient temperature of -10°C to 10°C, the unit amplitude ranges from 0.5% to 10%, and the duration of the intermittent period ranges from 15 to 30 seconds; the electrochemical device is a lithium cobalt oxide system electrochemical device, the electrochemical device is in an ambient temperature of 10°C to 45°C, the unit amplitude ranges from 0.5% to 10%, and the duration of the intermittent period ranges from 1 to 10 seconds. The embodiments of this application more specifically perform intermittent charging operations on electrochemical devices in different temperature environments, and can more accurately obtain the lithium plating SOC of electrochemical devices of different systems.

[0017] A second aspect of this application provides an electrochemical device including a processor and a machine-readable storage medium storing machine-executable instructions that can be executed by the processor, wherein the processor, when executing the machine-executable instructions, implements the steps of the method described in the first aspect above.

[0018] A third aspect of this application provides a battery module comprising: at least one heating element, a management unit, and an electrochemical device. The management unit is configured to perform a first charge-discharge cycle on the electrochemical device with a charging current, and to perform intermittent charging operations on the electrochemical device. During the intermittent charging operations, it acquires data related to the electrochemical device, determines the lithium plating state of charge (SOC) of the electrochemical device based on the related data, and, in response to the lithium plating SOC being less than or equal to an SOC threshold, controls at least one heating element to shunt the charging current and heat the electrochemical device. This embodiment of the application reduces the charging current of the electrochemical device by shunting the charging current with a heating element, thereby reducing the risk of lithium plating. The heat generated by the heating element allows the electrochemical device to be charged at a higher temperature, which also alleviates lithium plating and improves the safety of the electrochemical device, thus enhancing the safety of the battery module.

[0019] In one embodiment of this application, the SOC threshold includes n SOC thresholds that gradually decrease from i equal to 1 to n. When i is 1 to n-1, the number of heating elements used for shunting corresponding to the i-th SOC threshold is i. The management unit is further configured to: control the i heating elements to shun the charging current and heat the electrochemical device in response to the lithium plating SOC being less than or equal to the i-th SOC threshold, thereby further preventing lithium plating in the electrochemical device and extending the service life of the electrochemical device.

[0020] In one embodiment of this application, the management unit is further configured to control the electrochemical device to stop working in response to the lithium plating SOC being less than or equal to the nth SOC threshold; and to generate a prompt message that can prompt the user to replace the electrochemical device, thereby improving the user experience.

[0021] In one embodiment of this application, the heating element is disposed inside the electrochemical device and / or on the outer surface of the electrochemical device, thereby optimizing the arrangement of the heating element and enabling the heating element to heat the electrochemical device more effectively.

[0022] In one embodiment of this application, the heating element is made of at least one of nickel, nickel-aluminum alloy, copper, polyimide, silicone, or a positive temperature coefficient material; the impedance of the heating element ranges from 0.01Ω to 50Ω, and it has good heating performance.

[0023] In one embodiment of this application, the data related to the electrochemical device includes the state of charge (SOC) and internal resistance of the electrochemical device. The intermittent charging operation includes multiple charging periods and multiple interrupted periods. The management unit is specifically configured to: during the intermittent charging operation, for each of the multiple interrupted periods, acquire the SOC and internal resistance of the electrochemical device during the interrupted period; based on the acquired multiple SOCs of the electrochemical device and the multiple internal resistances of the electrochemical device corresponding to the multiple SOCs, obtain a first curve, the first curve being a mapping curve corresponding to the SOC and internal resistance of the electrochemical device; and based on the first curve, determine the lithium plating SOC of the electrochemical device.

[0024] In one embodiment of this application, the management unit is specifically used to: perform a first-order derivative on the first curve to obtain a second curve; and determine the SOC corresponding to the first point on the second curve where the slope is negative as the lithium plating SOC; or, perform a first-order derivative on the first curve to obtain a second curve; perform a second-order derivative on the second curve to obtain a third curve; and determine the SOC corresponding to the first point on the third curve where the ordinate is less than zero as the lithium plating SOC.

[0025] In one embodiment of this application, the intermittent charging operation includes multiple charging cycles, each charging cycle including a charging period and an intermittent period, during which the SOC of the electrochemical device increases by a unit magnitude.

[0026] In one embodiment of this application, the electrochemical device includes at least one of a lithium iron phosphate system electrochemical device, a lithium nickel cobalt manganese oxide system electrochemical device, or a lithium cobalt oxide system electrochemical device. Specifically, the management unit is used for: when the electrochemical device is a lithium iron phosphate system electrochemical device, the unit amplitude ranges from 0.5% to 10%, and the duration of the intermittent period ranges from 1 second to 15 seconds; when the electrochemical device is a lithium nickel cobalt manganese oxide system electrochemical device, the unit amplitude ranges from 0.5% to 10%, and the duration of the intermittent period ranges from 1 second to 30 seconds; when the electrochemical device is a lithium cobalt oxide system electrochemical device, the unit amplitude ranges from 0.5% to 10%, and the duration of the intermittent period ranges from 1 second to 30 seconds. This embodiment of the application more specifically performs intermittent charging operations on electrochemical devices of different systems, enabling more accurate determination of the lithium plating state of charge (SOC) for different electrochemical devices.

[0027] In one embodiment of this application, the management unit is specifically used for any one of the following a) to c): a) the electrochemical device is a lithium iron phosphate system electrochemical device, the electrochemical device is at an ambient temperature of -10°C to 10°C, the unit amplitude ranges from 0.5% to 10%, and the duration of the interruption period ranges from 5 seconds to 15 seconds; b) the electrochemical device is a lithium iron phosphate system electrochemical device, the electrochemical device is at an ambient temperature of 10°C to 45°C, the unit amplitude ranges from 0.5% to 10%, and the duration of the interruption period ranges from 1 second to 10 seconds; The duration of the interruption period ranges from 10 to 30 seconds; the electrochemical device is a lithium nickel cobalt manganese oxide system electrochemical device, the electrochemical device is in an ambient temperature range of 10°C to 45°C, the unit amplitude ranges from 0.5% to 10%, and the duration of the interruption period ranges from 1 to 10 seconds; c) the electrochemical device is a lithium cobalt oxide system electrochemical device, the electrochemical device is in an ambient temperature range of -10°C to 10°C, the unit amplitude ranges from 0.5% to 10%, and the duration of the interruption period ranges from 15 to 30 seconds; the electrochemical device is a lithium cobalt oxide system electrochemical device, the electrochemical device is in an ambient temperature range of 10°C to 45°C, the unit amplitude ranges from 0.5% to 10%, and the duration of the interruption period ranges from 1 to 10 seconds. The embodiments of this application more specifically perform intermittent charging operations on electrochemical devices in different temperature environments, and can more accurately obtain the lithium plating SOC of electrochemical devices of different systems.

[0028] In one embodiment of this application, the electrochemical systems of the electrochemical devices belonging to the same battery module are the same, so that the electrochemical devices in the battery module have good consistency.

[0029] The fourth aspect of this application provides an electrical device including the battery module provided in the third aspect above.

[0030] This application provides an electrochemical device management method, an electrochemical device, a battery module, and an electrical device. Based on data related to the electrochemical device obtained during intermittent charging operations, the lithium plating state of charge (SOC) of the electrochemical device is determined. In response to the SOC being less than or equal to a threshold value, at least one heating element is controlled to shunt the charging current and heat the electrochemical device. This application reduces the charging current of the electrochemical device by shunting the charging current with a heating element, thereby reducing the risk of lithium plating. The heat generated by the heating element allows the electrochemical device to charge at a higher temperature, further mitigating lithium plating and improving the safety of the electrochemical device. Of course, implementing any product or method of this application does not necessarily require achieving all of the above advantages simultaneously. Attached Figure Description

[0031] To more clearly illustrate the technical solutions of this application and the prior art, the accompanying drawings used in the embodiments and the prior art are briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application.

[0032] Figure 1 This is a flowchart illustrating an electrochemical device management method according to one embodiment of this application;

[0033] Figure 2 This is a schematic diagram of the structure of a heating element according to one embodiment of this application;

[0034] Figure 3 This is a schematic diagram of the first curve of one embodiment of this application;

[0035] Figure 4 This is a schematic diagram of the second curve according to one embodiment of this application;

[0036] Figure 5 This is a schematic diagram of the structure of a battery module according to one embodiment of this application. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided with reference to the accompanying drawings and embodiments. Obviously, the described embodiments are merely some embodiments of this application, and not all embodiments. All other technical solutions obtained by those skilled in the art based on the embodiments of this application fall within the scope of protection of this application.

[0038] It should be noted that, in the specific embodiments of this application, lithium-ion batteries are used as an example of electrochemical devices to explain this application, but the electrochemical devices of this application are not limited to lithium-ion batteries.

[0039] This application provides a method for managing an electrochemical device, such as... Figure 1As shown, the method includes the following steps:

[0040] S101: Perform the first charge-discharge cycle on the electrochemical device using the charging current;

[0041] The implementing entity in this application embodiment can be a battery management system (BMS). During the operation of the electrochemical device, the battery management system can manage the electrochemical device, such as managing the charging and discharging processes of the electrochemical device. The battery management system can be integrated into the electrochemical device or can be independent of the electrochemical device but communicate with it.

[0042] In this embodiment, the battery management system can control the charging current during the charge-discharge cycle of the electrochemical device. For example, during the operation of the electrochemical device, the management unit in the battery management system uses a charging current to perform charge-discharge cycles on the electrochemical device. The charge-discharge cycle in this embodiment can refer to the process of the electrochemical device performing a charge-discharge-charge cycle during operation.

[0043] In the first charge-discharge cycle, the aforementioned charging current can be used to charge the electrochemical device during the charging phase. Furthermore, the discharge current in the charge-discharge cycle can be adapted to the electrical equipment, and this application embodiment does not impose any limitations on this. The charging current in this application embodiment is not particularly limited; for example, it can be any current between 0.1A and 3A, such as 0.1A, 0.2A, 0.3A, 0.5A, 0.7A, 1A, 1.5A, 2A, 2.5A, or 3A.

[0044] S102: Perform intermittent charging operation on the electrochemical device, acquire data related to the electrochemical device during the intermittent charging operation, and determine the lithium plating SOC (State of Charge) of the electrochemical device based on the data related to the electrochemical device.

[0045] In this embodiment, intermittent charging operation can refer to the process of intermittently charging the electrochemical device. Lithium plating state of charge (SOC) can refer to the SOC related to the lithium plating state of the electrochemical device. For example, the management unit can perform intermittent charging operation on the electrochemical device; the management unit can be a microcontroller unit (MCU) in a battery management system.

[0046] In one example, after the management unit performs the first charge-discharge cycle of the electrochemical device for the first number of cycles, it performs an intermittent charging operation on the electrochemical device and performs lithium plating detection and analysis during the intermittent charging operation. Data related to the electrochemical device is acquired during the intermittent charging operation, and the state of charge (SOC) of the lithium plating in the electrochemical device is determined based on this data. The above-described process is for illustrative purposes only.

[0047] Data related to electrochemical devices can refer to data that reflects the state of the electrochemical device, including but not limited to data such as charging voltage, charging current, internal resistance, and state of charge (SOC).

[0048] This application does not impose any particular restrictions on the charging method in the intermittent charging operation. As long as the purpose of this application embodiment can be achieved, it can be constant voltage charging, constant current charging, constant current and constant voltage charging, or segmented constant current charging.

[0049] S103: In response to the lithium plating SOC being less than or equal to the SOC threshold, control at least one heating element to shunt the charging current and heat the electrochemical device.

[0050] In this embodiment, the electrochemical device can be heated by at least one heating element, and the heating element can also shunt the charging current. Exemplarily, the management unit performs intermittent charging of the electrochemical device, and performs lithium plating detection and analysis during the intermittent charging operation. When the lithium plating state of the electrochemical device is less than or equal to the state of charge threshold, at least one heating element connected to the electrochemical device is controlled to start working, heating the electrochemical device and shunting the charging current.

[0051] In this embodiment, the electrochemical device may refer to a single battery, and the heating element may be disposed inside the electrochemical device and / or on the outer surface of the electrochemical device. Or as... Figure 2 As shown, multiple electrochemical devices can form a battery module. Heating element 2 is disposed on the outer surface of electrochemical device 1. When the heating element is disposed on the outer surface of the electrochemical device, it can be positioned between the electrochemical devices. When the heating element is disposed inside the electrochemical device, it can be plate-shaped, preferably located outside the negative electrode plate of the electrochemical device. The heating element is provided with terminals for connection to an external current source.

[0052] In one implementation, the heating element is connected in parallel with the electrochemical device, and a switch is provided between the connection circuit of the heating element and the electrochemical device. The management unit can control the opening and closing of the switch to enable the heating element to work or stop.

[0053] The aforementioned SOC threshold can be a pre-set threshold. The SOC threshold can be stored in advance in a storage medium connected to the electrochemical device. The SOC threshold is generally set based on the SOC of an electrochemical device sample from the same system when lithium plating occurs. For example, the SOC threshold can be set to the SOC corresponding to the occurrence of lithium plating in an electrochemical device sample. Different SOC thresholds are typically set for electrochemical devices with different systems. For the same electrochemical device sample, the measured SOC corresponding to the occurrence of lithium plating will also differ at different charging rates and / or ambient temperatures.

[0054] In one embodiment of this application, the SOC threshold includes n SOC thresholds that gradually decrease from i equal to 1 to n. When i is 1 to n-1, the number of heating elements used for shunt corresponding to the i-th SOC threshold is i. Then, the above step S103 specifically is as follows:

[0055] In response to the lithium plating SOC being less than or equal to the i-th SOC threshold, i heating elements are controlled to shunt the charging current and heat the electrochemical device. In this embodiment, multiple heating elements, such as i heating elements, can be provided for the electrochemical device. Correspondingly, i SOC thresholds can be set, with these i SOC thresholds decreasing sequentially. Thus, when the lithium plating SOC is less than or equal to the i-th SOC threshold, the i heating elements can be controlled to shunt the charging current and heat the electrochemical device. This embodiment does not impose a particular upper limit on the number of SOC thresholds, as long as the purpose of this embodiment can be achieved. For example, n can be any positive integer from 3 to 10.

[0056] It is understandable that with the use of electrochemical devices, the higher the charging current and the lower the temperature, the easier it is for the electrochemical device to deposit lithium. The more heating elements used to shunt the charging current, the lower the charging current of the electrochemical device, and the higher the degree of heating. Based on this, the embodiments of this application can control different numbers of heating elements to shunt the charging current and heat the electrochemical device for different lithium deposition state of charge (SOC), thereby further preventing lithium deposition and extending the service life of the electrochemical device.

[0057] For example, there are three heating elements, and four SOC thresholds are set: a first SOC threshold, a second SOC threshold, a third SOC threshold, and a fourth SOC threshold (i.e., n=4), where the first SOC threshold ≥ the second SOC threshold ≥ the third SOC threshold ≥ the fourth SOC threshold. When the lithium plating SOC is less than or equal to the first SOC threshold, one heating element is controlled to shunt the charging current and heat the electrochemical device; when the lithium plating SOC is less than or equal to the second SOC threshold, two heating elements are controlled to shunt the charging current and heat the electrochemical device; when the lithium plating SOC is less than or equal to the third SOC threshold, three heating elements are controlled to shunt the charging current and heat the electrochemical device.

[0058] In one embodiment of this application, the method further includes:

[0059] In response to the lithium plating SOC being less than or equal to the nth SOC threshold, the electrochemical device is controlled to stop operating; a prompt message is generated.

[0060] For example, let's continue with the above-mentioned three heating elements and four SOC thresholds. When the lithium plating SOC is less than or equal to the fourth SOC threshold, it indicates that the lithium plating SOC of the electrochemical device has become very small, and the performance of the electrochemical device has degraded significantly. Therefore, the electrochemical device can be stopped from use, and the user can be prompted to replace the electrochemical device, thus improving the user experience.

[0061] The heating element in this application embodiment is made of at least one of nickel, nickel-aluminum alloy, copper, polyimide (PI), silicone, or PTC (Positive Temperature Coefficient) material. This application embodiment does not limit the structure of the heating element, as long as it achieves the purpose of this application; for example, the heating element can be sheet-like, film-like, etc.

[0062] The heating element in this embodiment has an impedance range of 0.01Ω to 50Ω, preferably 0.2Ω to 5Ω, and has good heating performance.

[0063] In one embodiment of this application, the data associated with the electrochemical device include the state of charge (SOC) and internal resistance of the electrochemical device, and the intermittent charging operation includes multiple charging periods and multiple interruption periods.

[0064] Intermittent charging operation can refer to the process of intermittently charging an electrochemical device. Data related to the electrochemical device can refer to data that reflects the state of the electrochemical device. The state of charge (SOC) of lithium plating in the electrochemical device is determined in the following way:

[0065] Step A: During the intermittent charging operation, for each of the multiple intermittent periods, obtain the SOC and internal resistance of the electrochemical device during that intermittent period.

[0066] In intermittent charging operations, the internal resistance of the electrochemical device can be determined based on the detected charging voltage and charging current. The BMS can pre-store a voltage-SOC relationship table, which records the SOC of the electrochemical device corresponding to different charging voltages; for example, 4.2V corresponds to 85% SOC, and 4.3V corresponds to 90% SOC. Therefore, the SOC of the electrochemical device can be determined based on the charging voltage and the voltage-SOC relationship table.

[0067] Step B: Based on the multiple SOCs of the obtained electrochemical device and the multiple internal resistances of the electrochemical device corresponding to the multiple SOCs, the first curve is obtained;

[0068] In this embodiment of the application, after obtaining the SOC and internal resistance during multiple intermittent periods of the electrochemical device, multiple data pairs consisting of SOC and internal resistance can be obtained, which can be referenced. Figure 3 We can use the SOC of the electrochemical device as the abscissa and the internal resistance of the electrochemical device as the ordinate, fill the points represented by these data pairs in the coordinate system, and obtain the first curve after fitting. The first curve represents the mapping curve between the SOC and the internal resistance of the electrochemical device.

[0069] It is understandable that the more intensive the acquisition of SOC and internal resistance data for the electrochemical device, the more data pairs are obtained, resulting in a more detailed first curve. In this embodiment, it is not necessarily required to acquire SOC and internal resistance data for all interruptions. That is, "each interruption" can refer to any interruption during which SOC and internal resistance data have already been acquired, rather than requiring the acquisition of SOC and internal resistance data for all interruptions. As long as a sufficient number of SOC and internal resistance data points are acquired to obtain the first curve, it is acceptable. The process of curve fitting using data is well known to those skilled in the art, and the comparison of embodiments in this application does not impose specific limitations.

[0070] Step C: Based on the first curve, determine the state of lithium plating (SOC) of the electrochemical device.

[0071] The first curve represents the mapping relationship between the SOC and internal resistance of the electrochemical device. The lithium plating SOC of the electrochemical device can be determined based on the first curve.

[0072] The aforementioned lithium plating SOC may not be measured in real time, but rather obtained from the charging voltage obtained during intermittent charging operations and a voltage-SOC relationship table, which can be pre-stored in the storage medium of the battery management system.

[0073] In one embodiment, the process of determining the lithium plating state of the electrochemical device based on the first curve can be method 1, which includes:

[0074] i: Take the first derivative of the first curve to obtain the second curve;

[0075] like Figure 4 As shown, the second curve is obtained by taking the first derivative of the first curve. This second curve represents the rate of change of the internal resistance of the electrochemical device with SOC.

[0076] ii: Determine the SOC corresponding to the point where the slope of the second curve first appears negative as the lithium plating SOC.

[0077] The second curve represents the rate of change of internal resistance with SOC. When the rate of change does not show an abnormal decrease in the flat region of the curve, it indicates that no active lithium has been deposited. When the rate of change shows an abnormal decrease in the flat region of the curve, it is because active lithium has been deposited on the surface of the negative electrode and is in contact with the negative electrode. This is equivalent to a lithium metal device being connected in parallel with the graphite part of the negative electrode, which reduces the impedance of the entire negative electrode. Therefore, the impedance of the electrochemical device shows an abnormal decrease when active lithium is deposited, and correspondingly, the flat region of the second curve shows an abnormal decrease. (Reference) Figure 4 Point B marks the first time the slope of the second curve becomes negative. This means that the flat area of ​​the second curve at point B shows an abnormal decrease for the first time, indicating that the electrochemical device is showing a tendency to or has already undergone lithium plating at point B. Therefore, the State of Charge (SOC) corresponding to point B can be determined as the lithium plating SOC. Based on the relationship between the lithium plating SOC and the SOC threshold, timely protection measures can be taken for the electrochemical device, improving its operational safety. Steps A to C above are only used to illustrate the order of the steps, not to limit their execution.

[0078] In one implementation, the process of determining the lithium plating state of the electrochemical device based on the first curve can be method 2, which includes:

[0079] i': Take the first derivative of the first curve to obtain the second curve;

[0080] This step is the same as step i in method 1, and will not be repeated here.

[0081] ii': Taking the second derivative of the second curve yields the third curve;

[0082] The second curve can also be differentiated by its second order to obtain the third curve. It can be understood that the third curve is the second-order differential curve of the second curve.

[0083] iii': Determine the SOC corresponding to the point where the ordinate of the third curve first appears to be less than zero as the lithium plating SOC.

[0084] If the ordinate of the third curve is less than zero, the SOC corresponding to the first point where the ordinate of the third curve is less than zero is determined as the lithium plating SOC. In this embodiment, the ordinate of the third curve is the second-order differential internal resistance, and the abscissa of the third curve is the state of charge.

[0085] Intermittent charging operation can refer to the process of intermittently charging an electrochemical device. In one embodiment, intermittent charging operation may include multiple charging cycles, each charging cycle comprising a charging period and an intermittent period, during which the state of charge (SOC) of the electrochemical device increases by a unit increment. That is, the SOC of the electrochemical device is increased by a certain increment during each charging period, for example, by 0.5%, 1%, 5%, or 10% of the SOC during each charging period.

[0086] The intermittent charging operation of this application embodiment includes multiple charging cycles, each charging cycle including a charging period and an interruption period. Exemplarily, a first charging period and a first interruption period form a first charging cycle, a second charging period and a second interruption period form a second charging cycle, a third charging period and a third interruption period form a third charging cycle, and so on. It is understood that a charging cycle is a continuous time period.

[0087] In one implementation, the intermittent charging operation can be specifically described as follows: For any one of multiple charging cycles, the electrochemical device is charged at a first moment until the State of Charge (SOC) of the electrochemical device increases by a unit magnitude, at which point charging stops, until a third moment. The moment at which charging stops is the second moment, and the time interval between the third moment and the second moment is the duration of the intermittent period. During the intermittent period, the electrochemical device can be in a state of neither charging nor discharging, i.e., a static state.

[0088] For example, if the electrochemical device is charged at time T1 until the state of charge (SOC) of the electrochemical device increases by a unit magnitude, and then the charging stops, the time when the charging stops is time T2; starting from time T2, the electrochemical device is left to stand, and the time when the standing ends is time T3.

[0089] This application embodiment, by performing intermittent charging operation on the electrochemical device, can obtain data related to the electrochemical device during the intermittent charging operation. Based on this data, the lithium plating state occupancy (SOC) of the electrochemical device can be determined, which makes it easier to take protective measures for the electrochemical device in the future.

[0090] The electrochemical device in this application includes at least one of a lithium iron phosphate system, a lithium nickel cobalt manganese oxide system, or a lithium cobalt oxide system. Generally, in intermittent charging operations, different electrochemical systems correspond to different unit amplitudes and different intermittent periods. Based on this:

[0091] In one embodiment, the electrochemical device is a lithium iron phosphate system electrochemical device, with a unit amplitude ranging from 0.5% to 10% and an intermittent period duration ranging from 1 second to 15 seconds.

[0092] In one embodiment, the electrochemical device is a lithium nickel cobalt manganese oxide system electrochemical device, with a unit amplitude ranging from 0.5% to 10% and an intermittent period duration ranging from 1 second to 30 seconds.

[0093] In one embodiment, the electrochemical device is a lithium cobalt oxide system electrochemical device, with a unit amplitude ranging from 0.5% to 10% and an intermittent period duration ranging from 1 second to 30 seconds.

[0094] This application embodiment sets different unit amplitudes and intermittent periods for different electrochemical devices, enabling more targeted intermittent charging operations for different electrochemical devices, and thus more accurately obtaining the lithium plating SOC of different electrochemical devices.

[0095] Generally speaking, in intermittent charging operations, for the same electrochemical system, different temperature conditions will correspond to different unit amplitudes and different durations of interruptions. Based on this:

[0096] In one embodiment, the electrochemical device is a lithium iron phosphate system electrochemical device, operating at an ambient temperature of -10°C to 10°C, with a unit amplitude ranging from 0.5% to 10%, and an intermittent period duration ranging from 5 seconds to 15 seconds. In another embodiment, the electrochemical device is a lithium iron phosphate system electrochemical device, operating at an ambient temperature of 10°C to 45°C, with a unit amplitude ranging from 0.5% to 10%, and an intermittent period duration ranging from 1 second to 10 seconds.

[0097] In the embodiments of this application, the positive electrode of the lithium iron phosphate system electrochemical device may also include other positive electrode active materials, but lithium iron phosphate is the main material. For example, lithium iron phosphate accounts for any one of 51%, 60%, 70%, 80%, 90%, or 98% of the total mass of the positive electrode active material.

[0098] In one embodiment, the electrochemical device is a lithium nickel cobalt manganese oxide system electrochemical device, operating at an ambient temperature of -10°C to 10°C, with a unit amplitude ranging from 0.5% to 10%, and an intermittent period duration ranging from 10 seconds to 30 seconds. In another embodiment, the electrochemical device is a lithium nickel cobalt manganese oxide system electrochemical device, operating at an ambient temperature of 10°C to 45°C, with a unit amplitude ranging from 0.5% to 10%, and an intermittent period duration ranging from 1 second to 10 seconds.

[0099] In the embodiments of this application, the positive electrode of the lithium nickel cobalt manganese oxide system electrochemical device may also include other positive electrode active materials, but lithium nickel cobalt manganese oxide is the main material. For example, lithium nickel cobalt manganese oxide accounts for any of the following values ​​of the total mass of the positive electrode active material: 51%, 60%, 70%, 80%, 90%, and 98%.

[0100] In one embodiment, the electrochemical device is a lithium cobalt oxide system electrochemical device, operating at an ambient temperature of -10°C to 10°C, with a unit amplitude ranging from 0.5% to 10%, and an intermittent period duration ranging from 15 seconds to 30 seconds. In another embodiment, the electrochemical device is a lithium cobalt oxide system electrochemical device, operating at an ambient temperature of 10°C to 45°C, with a unit amplitude ranging from 0.5% to 10%, and an intermittent period duration ranging from 1 second to 10 seconds.

[0101] In the embodiments of this application, the positive electrode of the lithium cobalt oxide system electrochemical device may also include other positive electrode active materials, but lithium cobalt oxide is the main material. For example, lithium cobalt oxide accounts for any of the following values ​​of the total mass of the positive electrode active material: 51%, 60%, 70%, 80%, 90%, and 98%.

[0102] This application embodiment sets different unit amplitudes and intermittent durations for electrochemical devices in the same electrochemical system at different temperatures, enabling more targeted intermittent charging operations for electrochemical devices in different temperature environments, and thus more accurately obtaining the lithium plating SOC of electrochemical devices in different systems.

[0103] In one implementation, the step of generating the first curve includes:

[0104] Step a: Obtain the first voltage, first current, and first SOC of the electrochemical device at a second time point, and the second voltage and second current of the electrochemical device at a third time point;

[0105] The second moment is the moment when charging stops. The voltage, current, and state of charge (SOC) of the electrochemical device at the second moment can be obtained, namely the first voltage, the first current, and the first SOC, denoted as V1, I1, and SOC1, respectively. Similarly, the voltage and current of the electrochemical device at the third moment can be obtained, namely the second voltage and the second current, denoted as V2 and I2, respectively.

[0106] Step b: Calculate the voltage and current changes of the electrochemical device during the intermittent period.

[0107] The duration of the interruption is the time interval between the third moment and the second moment. The voltage change of the electrochemical device during the interruption is ΔV, where ΔV = V2 - V1. The current change of the electrochemical device during the interruption is ΔI, where ΔI = I2 - I1.

[0108] Step c: Calculate the first internal resistance of the electrochemical device during the intermittent period based on the voltage change value and the current change value, and use the first internal resistance and the first SOC as one of the data pairs of the first curve, wherein the data pair is the correspondence between internal resistance and SOC.

[0109] The first internal resistance of the electrochemical device during the intermittent period is R1, where R1 = ΔV / ΔI. R1 and SOC1 are used as one data pair for the first curve.

[0110] Multiple data pairs can be obtained by using the same method described above.

[0111] Step d: Generate the first curve based on the calculated data pairs.

[0112] Using the state of charge (SOC) of the electrochemical device as the abscissa and the internal resistance of the electrochemical device as the ordinate, the points represented by these data pairs are filled into a coordinate system, and a first curve is obtained after fitting. In this embodiment of the application, after obtaining the first curve, the lithium plating SOC of the electrochemical device can be determined through the first curve, allowing for timely diversion and heating of the electrochemical device, thereby improving its service life.

[0113] This application provides an electrochemical device management method. Based on data related to the electrochemical device acquired during intermittent charging operations, the method determines the state of charge (SOC) for lithium plating in the electrochemical device. In response to an SOC less than or equal to a threshold value, it controls at least one heating element to shunt the charging current and heat the electrochemical device. This application reduces the charging current of the electrochemical device by shunting the charging current with a heating element, thereby reducing the risk of lithium plating. The heat generated by the heating element allows the electrochemical device to charge at a higher temperature, further mitigating lithium plating and improving the safety of the electrochemical device.

[0114] This application also provides an electrochemical device, including a processor and a machine-readable storage medium, wherein the machine-readable storage medium stores machine-executable instructions that can be executed by the processor, and when the processor executes the machine-executable instructions, it implements the electrochemical device management method described in any of the above embodiments.

[0115] This application also provides a battery module, including a management unit, an electrochemical device, and at least one heating element. The management unit is used to perform a first charge-discharge cycle on the electrochemical device with a charging current, and to perform intermittent charging operations on the electrochemical device. During the intermittent charging operations, it acquires data related to the electrochemical device, determines the lithium plating SOC of the electrochemical device based on the relevant data, and, in response to the lithium plating SOC being less than or equal to a SOC threshold, controls at least one heating element to shunt the charging current and heat the electrochemical device. It is understood that the differences between the electrochemical devices in a battery module are usually very small, and their lithium plating SOCs are basically the same. Therefore, when the lithium plating SOC of one electrochemical device is measured, it can be considered that the lithium plating SOCs of the other electrochemical devices in the battery module have been obtained.

[0116] In one example, refer to Figure 5 The battery module 500 includes i heating elements 2 (for example, i can be 3), the i heating elements 2 are connected in parallel with the electrochemical device 1, and a switch 5 is provided between each heating element 2 and the parallel circuit of the electrochemical device 1. The management unit 4 can control the opening and closing of the i switches 5, thereby controlling the number of heating elements 2 used for shunt charging current and heating the electrochemical device.

[0117] In another implementation, the battery module 500 may also include multiple electrochemical devices. The heating element 2 described above may be disposed inside the electrochemical device or on the outer surface of the electrochemical device.

[0118] In one implementation, the SOC threshold includes n SOC thresholds that gradually decrease from i equal to 1 to n. When i is 1 to n-1, the number of heating elements used for shunt corresponding to the i-th SOC threshold is i. The management unit is further configured to:

[0119] In response to the lithium plating SOC being less than or equal to the i-th SOC threshold, the i-th heating elements are controlled to shunt the charging current and heat the electrochemical device.

[0120] In one implementation, the management unit is also used for:

[0121] In response to the lithium plating SOC being less than or equal to the nth SOC threshold, the electrochemical device is controlled to stop working.

[0122] Generate a prompt message.

[0123] In one embodiment, the heating element is made of at least one of nickel, nickel-aluminum alloy, copper, polyimide, silicone, or a positive temperature coefficient material; the impedance of the heating element ranges from 0.01Ω to 50Ω.

[0124] In one embodiment, data related to the electrochemical device includes the state of charge (SOC) and internal resistance of the electrochemical device. The intermittent charging operation includes multiple charging periods and multiple interruptions. The management unit is specifically used for:

[0125] During the intermittent charging operation, for each of the multiple intermittent periods, the SOC and internal resistance of the electrochemical device during the intermittent period are obtained. Based on the multiple SOCs of the electrochemical device and the multiple internal resistances of the electrochemical device corresponding to the multiple SOCs, a first curve is obtained. The first curve is a mapping curve corresponding to the SOC and internal resistance of the electrochemical device.

[0126] Based on the first curve, the state of lithium deposition (SOC) of the electrochemical device was determined.

[0127] In one implementation, the management unit is specifically used for:

[0128] Taking the first derivative of the first curve yields the second curve; and

[0129] The SOC corresponding to the point where the slope of the second curve first appears negative is determined to be the SOC of lithium plating;

[0130] or

[0131] The second curve is obtained by taking the first derivative of the first curve.

[0132] Taking the second derivative of the second curve yields the third curve; and

[0133] The SOC corresponding to the first point on the third curve where the ordinate is less than zero is determined to be the SOC for lithium plating.

[0134] In one embodiment, the intermittent charging operation includes multiple charging cycles, each charging cycle including a charging period and an intermittent period, during which the SOC of the electrochemical device increases by a unit magnitude.

[0135] In one embodiment, the electrochemical device includes at least one of a lithium iron phosphate system electrochemical device, a lithium nickel cobalt manganese oxide system electrochemical device, or a lithium cobalt oxide system electrochemical device, wherein the management unit is specifically used for:

[0136] The electrochemical device is a lithium iron phosphate system electrochemical device, with a unit amplitude ranging from 0.5% to 10% and an intermittent duration ranging from 1 second to 15 seconds;

[0137] The electrochemical device is a lithium nickel cobalt manganese oxide system electrochemical device, with a unit amplitude ranging from 0.5% to 10% and an intermittent duration ranging from 1 second to 30 seconds;

[0138] The electrochemical device is a lithium cobalt oxide system electrochemical device with a unit amplitude ranging from 0.5% to 10% and an intermittent period duration ranging from 1 second to 30 seconds.

[0139] In one implementation, the management unit is specifically used for any one of the following a) to c):

[0140] a) The electrochemical device is a lithium iron phosphate system electrochemical device, the electrochemical device is in an ambient temperature range of -10℃ to 10℃, the unit amplitude range is 0.5% to 10%, and the duration of the intermittent period ranges from 5 seconds to 15 seconds; the electrochemical device is a lithium iron phosphate system electrochemical device, the electrochemical device is in an ambient temperature range of 10℃ to 45℃, the unit amplitude range is 0.5% to 10%, and the duration of the intermittent period ranges from 1 second to 10 seconds;

[0141] b) The electrochemical device is a lithium nickel cobalt manganese oxide system electrochemical device, the electrochemical device is in an ambient temperature range of -10℃ to 10℃, the unit amplitude range is 0.5% to 10%, and the duration of the intermittent period ranges from 10 seconds to 30 seconds; the electrochemical device is a lithium nickel cobalt manganese oxide system electrochemical device, the electrochemical device is in an ambient temperature range of 10℃ to 45℃, the unit amplitude range is 0.5% to 10%, and the duration of the intermittent period ranges from 1 second to 10 seconds;

[0142] c) The electrochemical device is a lithium cobalt oxide system electrochemical device, the electrochemical device is in an ambient temperature range of -10℃ to 10℃, the unit amplitude range is 0.5% to 10%, and the duration of the intermittent period ranges from 15 seconds to 30 seconds; the electrochemical device is a lithium cobalt oxide system electrochemical device, the electrochemical device is in an ambient temperature range of 10℃ to 45℃, the unit amplitude range is 0.5% to 10%, and the duration of the intermittent period ranges from 1 second to 10 seconds.

[0143] In one implementation, the electrochemical devices belonging to the same battery module have the same electrochemical system, which ensures good consistency among the electrochemical devices in the battery module.

[0144] This application provides a battery module in which a management unit determines the state of charge (SOC) of the electrochemical device based on data acquired during intermittent charging operations. In response to an SOC less than or equal to a threshold value, the management unit controls at least one heating element to shunt the charging current and heat the electrochemical device. This embodiment reduces the charging current of the electrochemical device by shunting the charging current through the heating element, thereby reducing the risk of lithium plating. The heat generated by the heating element charges the electrochemical device at a higher temperature, further mitigating lithium plating and improving the safety of the electrochemical device, thus enhancing the safety of the battery module.

[0145] This application also provides an electrical device, including the electrochemical device described in the above embodiments.

[0146] Machine-readable storage media may include random access memory (RAM) or non-volatile memory, such as at least one disk storage device. Optionally, the memory may also be at least one storage device located remotely from the aforementioned processor.

[0147] The processors mentioned above can be general-purpose processors, including central processing units (CPUs), network processors (NPs), etc.; they can also be digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components.

[0148] For the embodiments of electrochemical devices / electrical equipment, since they are basically similar to the method embodiments, the description is relatively simple, and relevant parts can be found in the description of the method embodiments.

[0149] Preparation Example 1

[0150] Preparation of electrochemical devices based on lithium nickel cobalt manganese oxide system :

[0151] Preparation of the positive electrode sheet: Lithium nickel cobalt manganese oxide, acetylene black, and polyvinylidene fluoride (PVDF) were mixed in a mass ratio of 94:3:3. N-methylpyrrolidone (NMP) was then added as a solvent to prepare a slurry with a solid content of 75%, and the mixture was stirred evenly. The slurry was uniformly coated onto one surface of a 12 μm thick aluminum foil, dried at 90°C, and cold-pressed to obtain a positive electrode sheet with a 100 μm thick positive active material layer. The above steps were repeated on the other surface of the same positive electrode sheet to obtain a positive electrode sheet with positive active material layers coated on both sides. The positive electrode sheet was cut to a size of (74 mm × 867 mm) and tabs were welded on for later use.

[0152] Preparation of the negative electrode sheet: Artificial graphite, acetylene black, styrene-butadiene rubber, and sodium carboxymethyl cellulose (CMC) were mixed in a mass ratio of 96:1:1.5:1.5. Deionized water was then added as a solvent to prepare a slurry with a solid content of 70%, and the mixture was stirred evenly. The slurry was uniformly coated onto one surface of an 8 μm thick copper foil, dried at 110°C, and cold-pressed to obtain a single-sided negative electrode sheet with a 150 μm thick negative active material layer. The coating process was repeated on the other surface of the same negative electrode sheet to obtain a double-sided negative electrode sheet. The negative electrode sheet was cut to a size of 74 mm × 867 mm and tabs were welded on for later use.

[0153] Preparation of the separator: A porous polyethylene (PE) film with a thickness of 15 μm was used as the separator.

[0154] Preparation of electrolyte: In an environment with a water content of less than 10 ppm, non-aqueous organic solvents ethylene carbonate (EC), propylene carbonate (PC), and diethyl carbonate (DEC) were mixed in a mass ratio of 1:1:1. Then, lithium hexafluorophosphate (LiPF6) was added to the non-aqueous organic solvents, dissolved, and mixed evenly to obtain the electrolyte, wherein the concentration of LiPF6 was 1.15 mol / L.

[0155] Preparation of an electrochemical device with a heating element: The prepared positive electrode, separator, and negative electrode are stacked in sequence, with the separator positioned between the positive and negative electrodes to provide isolation. The heating element (impedance selectable) is placed in the innermost layer of the electrochemical device, i.e., in the middle of the first turn of the separator, and then wound to obtain the electrode assembly. The electrode assembly is placed in an aluminum-plastic film packaging bag and dehydrated at 80°C. The prepared electrolyte is then injected, and after vacuum sealing, settling, formation, and shaping, the electrochemical device with a rated capacity of 5Ah is obtained.

[0156] Preparation Example 2

[0157] Except that the electrochemical device does not contain a heating element, it is the same as in Preparation Example 1.

[0158] Example 1

[0159] <Settings of heating elements and switches>

[0160] Two electrochemical devices were prepared according to the method of Preparation Example 1, and the two electrochemical devices were connected in series to form a battery module. Each electrochemical device has a nickel heating element with an impedance of 2Ω in its innermost layer. The switch used to control the switching of the nickel heating element inside the electrochemical device (hereinafter referred to as the first heating element) is defined as switch ①.

[0161] <Protection Operation of Electrochemical Devices>

[0162] The electrochemical device was subjected to intermittent charging, and the lithium plating state of charge (SOC) was obtained after lithium plating detection.

[0163] If the lithium plating SOC is less than or equal to the first SOC threshold, control switch ① closes, the first heating element shunts the charging current and heats the electrochemical device, and the electrochemical device charges normally. If the second SOC threshold is less than or equal to the first SOC threshold, switch ① remains closed, and the electrochemical device continues to be used. If the lithium plating SOC is less than or equal to the second SOC threshold, the electrochemical device immediately stops use and the user is prompted to replace it. The first SOC threshold is 30%, and the second SOC threshold is 29%. Record the lithium plating SOC, the number of charge-discharge cycles, the minimum constant current charging current, and the total charging time of the electrochemical device, as well as the number of cycles and charging time at different stages. Different stages refer to the charge-discharge cycle stages corresponding to different numbers of switch closures.

[0164] Example 2

[0165] <Settings of heating elements and switches>

[0166] Except for the fact that a nickel heating element with an impedance of 1Ω is placed between the two electrochemical devices, and the switch for controlling the nickel heating element (hereinafter referred to as the second heating element) between the electrochemical devices is defined as switch ②, the rest is the same as in Example 1.

[0167] <Protection Operation of Electrochemical Devices>

[0168] The electrochemical device was subjected to intermittent charging, and the lithium plating state of charge (SOC) was obtained after lithium plating detection.

[0169] If the lithium plating SOC is less than or equal to the first SOC threshold, control switch ① is closed, the first heating element shunts the charging current and heats the electrochemical device, and the electrochemical device charges normally. If the second SOC threshold is less than or equal to the first SOC threshold, switch ① remains closed, and the electrochemical device continues to be used. If the lithium plating SOC is less than or equal to the second SOC threshold, switches ① and ② are closed, the first and second heating elements jointly shunt the charging current and heat the electrochemical device, and the electrochemical device charges normally. If the third SOC threshold is less than or equal to the second SOC threshold, switches ① and ② remain closed, and the electrochemical device continues to be used. If the lithium plating SOC is less than or equal to the third SOC threshold, the electrochemical device immediately stops operating and the user is prompted to replace it. The first SOC threshold is 30%, the second SOC threshold is 29%, and the third SOC threshold is 28%.

[0170] Example 3

[0171] <Settings of heating elements and switches>

[0172] Except for attaching a nickel heating element with an impedance of 0.1Ω to the outer surface of the two electrochemical devices, and the switch used to control the outer nickel heating element of the electrochemical device (hereinafter referred to as the third heating element) is called switch ③, the rest is the same as in Example 2.

[0173] <Protection Operation of Electrochemical Devices>

[0174] The electrochemical device was subjected to intermittent charging, and the lithium plating state of charge (SOC) was obtained after lithium plating detection.

[0175] If the lithium plating SOC is less than or equal to the first SOC threshold, control switch ① is closed, the first heating element shunts the charging current and heats the electrochemical device, and the electrochemical device charges normally. If the second SOC threshold is less than or equal to the first SOC threshold, switch ① remains closed, and the electrochemical device continues to be used. If the lithium plating SOC is less than or equal to the second SOC threshold, switches ① and ② are closed, the first and second heating elements jointly shunt the charging current and heat the electrochemical device, and the electrochemical device charges normally. If the third SOC threshold is less than or equal to the second SOC threshold, switches ① and ② remain closed, and the electrochemical device continues to be used. If the lithium plating SOC is less than or equal to the third SOC threshold, control switches ①, ②, and ③ are closed, the first, second, and third heating elements jointly shunt the charging current and heat the electrochemical device, and the electrochemical device charges normally. If the fourth SOC threshold is less than or equal to the third SOC threshold, switches ①, ②, and ③ remain closed, and the electrochemical device continues to be used. If the lithium plating SOC is less than or equal to the fourth SOC threshold, the electrochemical device immediately stops working and prompts the user to replace it. The first SOC threshold is 30%, the second SOC threshold is 29%, the third SOC threshold is 28%, and the fourth SOC threshold is 26%.

[0176] Example 4

[0177] <Settings of heating elements and switches>

[0178] Except that each electrochemical device has a copper heating element with an impedance of 2Ω at its innermost layer and a nickel heating element with an impedance of 0.05Ω attached to the outer surface of the two electrochemical devices, the rest is the same as in Example 3.

[0179] The protection operation of the electrochemical device is the same as in Example 3.

[0180] Example 5

[0181] <Settings of heating elements and switches>

[0182] Except for the innermost layer of each electrochemical device having a nickel heating element with an impedance of 5Ω, the rest is the same as in Example 3.

[0183] The protection operation of the electrochemical device is the same as in Example 3.

[0184] Example 6

[0185] <Settings of heating elements and switches>

[0186] Except for the innermost layer of each electrochemical device having a nickel heating element with an impedance of 8Ω, the rest is the same as in Example 3.

[0187] The protection operation of the electrochemical device is the same as in Example 3.

[0188] Comparative Example 1

[0189] <Detection of Electrochemical Devices>

[0190] Two electrochemical devices were prepared according to the method of Preparation Example 2, and the two electrochemical devices were connected in series to form a battery module. The following charge-discharge cycle was performed: constant current charging at 5A to 4.4V, constant voltage charging until the current drops to 250mA, resting for 15min, then constant current discharging at 5A to 2.8V, resting for 15min, and repeating the above charge-discharge cycle. Lithium plating was detected during each charge until lithium plating SOC was detected.

[0191] <Protection Operation of Electrochemical Devices>

[0192] If the SOC of lithium plating exceeds the first SOC threshold, the electrochemical device operates normally; if the SOC of lithium plating is less than or equal to the first SOC threshold, the electrochemical device immediately stops operation and the user is prompted to replace it. The first SOC threshold is 30%.

[0193] Comparative Example 2

[0194] Except for the <Protection Operation of Electrochemical Device>, which differs from Comparative Example 1, everything else is the same as Comparative Example 1.

[0195] <Protection Operation of Electrochemical Devices>

[0196] If the lithium plating SOC is greater than the first SOC threshold, the electrochemical device operates normally. If the lithium plating SOC is less than or equal to the first SOC threshold, the electrochemical device immediately stops operating and prompts the user for replacement. If the second SOC threshold is less than or equal to the lithium plating SOC and less than the first SOC threshold, the charging current is reduced by a first increment of 0.1 × the electrochemical device capacity. The electrochemical device continues to operate, and the lithium plating SOC is detected again during the next charge to reassess the relationship between the lithium plating SOC and the first and second SOC thresholds, and so on. The first SOC threshold is 30%, and the second SOC threshold is 29%.

[0197] The data from Examples 1 to 6 and Comparative Examples 1 to 2 are shown in Table 1:

[0198] Table 1

[0199] Example 1 28.3％ 701 5A 63min Example 2 27.5％ 751 5A 70min Example 3 25.3％ 819 5A 74min Example 4 25.2％ 821 5A 74min Example 5 20.5％ 1069 5A 78min Example 6 18.7％ 1100 5A 137min Comparative Example 1 29.9％ 622 5A 59min Comparative Example 2 27.9％ 987 4A 77min

[0200] The number of cycles and charging time for different stages of Examples 1 to 6 are shown in Table 2:

[0201] Table 2

[0202]

[0203] As can be seen from Example 1 and Comparative Examples 1 and 2, the SOC detected by them is not much different from that detected by the comparative examples, indicating that the method of this application can also effectively detect the SOC of lithium plating in electrochemical devices.

[0204] As can be seen from Examples 1 to 6 and Comparative Examples 1 and 2, by setting a heating element to shunt the charging current and heat the electrochemical device, the number of cycles of the electrochemical device can be increased, thereby extending the service life of the electrochemical device and improving the user experience.

[0205] It can also be seen from Examples 1 to 6 that by setting heating elements of different numbers and impedances, the number of cycles of the electrochemical device can be increased, thereby extending the service life of the electrochemical device and improving the user experience.

[0206] As can be seen from Examples 5 and 6, the larger the resistance of the heating element in the early stage (e.g., greater than 5Ω), the smaller the impact on the charging time, but the easier it is to reach the lithium plating critical point in the next stage.

[0207] As can be seen from Examples 3 and 4, the smaller the impedance of the heating element in the third stage (e.g., less than 0.1Ω), the longer the electrochemical device can be used (the more cycles it can be cycled), but the charging time will increase.

[0208] The above description is only a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A method for managing an electrochemical device, characterized in that, The method includes: The electrochemical device is subjected to a first charge-discharge cycle using a charging current. An intermittent charging operation is performed on the electrochemical device, and data related to the electrochemical device is acquired during the intermittent charging operation. Based on the relevant data, the lithium plating state of the electrochemical device is determined. In response to the lithium plating SOC being less than or equal to the SOC threshold, at least one heating element is controlled to shunt the charging current and heat the electrochemical device; Wherein, the SOC threshold includes n SOC thresholds that gradually decrease from i equal to 1 to n. When i is 1 to n-1, the number of heating elements used for current shunting corresponding to the i-th SOC threshold is i. The step of controlling at least one heating element to shun the charging current and heat the electrochemical device in response to the lithium plating SOC being less than or equal to the SOC threshold includes: In response to the lithium plating SOC being less than or equal to the i-th SOC threshold, the i-th heating element is controlled to shunt the charging current and heat the electrochemical device.

2. The electrochemical device management method according to claim 1, characterized in that, The method further includes: In response to the lithium plating SOC being less than or equal to the nth SOC threshold, the electrochemical device is controlled to stop operating; Generate a prompt message.

3. The electrochemical device management method according to claim 1, characterized in that, The heating element is disposed inside the electrochemical device and / or on the outer surface of the electrochemical device.

4. The electrochemical device management method according to claim 1, characterized in that, The heating element is made of at least one of nickel, nickel-aluminum alloy, copper, polyimide, silicone, or a positive temperature coefficient material; the impedance of the heating element ranges from 0.01Ω to 50Ω.

5. The electrochemical device management method according to claim 1, characterized in that, The data related to the electrochemical device includes the state of charge (SOC) and internal resistance of the electrochemical device. The intermittent charging operation includes multiple charging periods and multiple interruptions. The step of acquiring the data related to the electrochemical device during the intermittent charging operation and determining the lithium plating SOC of the electrochemical device based on the related data includes: During the intermittent charging operation, for each of the plurality of intermittent periods, the SOC and internal resistance of the electrochemical device during the intermittent period are obtained. Based on the plurality of SOCs of the electrochemical device and the plurality of internal resistances of the electrochemical device corresponding to the plurality of SOCs, a first curve is obtained. The first curve is a mapping curve corresponding to the SOC and internal resistance of the electrochemical device. Based on the first curve, the state of lithium deposition (SOC) of the electrochemical device is determined.

6. The electrochemical device management method according to claim 5, characterized in that, The step of determining the lithium plating state of the electrochemical device based on the first curve includes at least one of method 1 or method 2, wherein: Method 1 includes: Taking the first derivative of the first curve yields the second curve; and The SOC corresponding to the first point on the second curve with a negative slope is determined as the SOC for lithium plating. Method 2 includes: The second curve is obtained by taking the first derivative of the first curve; Taking the second derivative of the second curve yields the third curve; and The SOC corresponding to the point where the ordinate of the third curve first appears to be less than zero is determined as the lithium plating SOC.

7. The electrochemical device management method according to claim 1, characterized in that, The intermittent charging operation includes multiple charging cycles, each charging cycle including a charging period and an intermittent period, during which the SOC of the electrochemical device increases by a unit magnitude.

8. The electrochemical device management method according to claim 7, characterized in that, The electrochemical device includes at least one of a lithium iron phosphate system electrochemical device, a nickel-cobalt-manganese oxide system electrochemical device, or a lithium cobalt oxide system electrochemical device, wherein... The electrochemical device is a lithium iron phosphate system electrochemical device, the unit amplitude ranges from 0.5% to 10%, and the duration of the intermittent period ranges from 1 second to 15 seconds; The electrochemical device is a lithium nickel cobalt manganese oxide system electrochemical device, the unit amplitude ranges from 0.5% to 10%, and the duration of the intermittent period ranges from 1 second to 30 seconds; The electrochemical device is a lithium cobalt oxide system electrochemical device, the unit amplitude ranges from 0.5% to 10%, and the duration of the intermittent period ranges from 1 second to 30 seconds.

9. The electrochemical device management method according to claim 8, characterized in that, The intermittent charging device is specifically used for any one of the following a) to c): a) The electrochemical device is a lithium iron phosphate system electrochemical device, the electrochemical device is in an ambient temperature range of -10℃ to 10℃, the unit amplitude ranges from 0.5% to 10%, and the duration of the intermittent period ranges from 5 seconds to 15 seconds; the electrochemical device is a lithium iron phosphate system electrochemical device, the electrochemical device is in an ambient temperature range of 10℃ to 45℃, the unit amplitude ranges from 0.5% to 10%, and the duration of the intermittent period ranges from 1 second to 10 seconds; b) The electrochemical device is a lithium nickel cobalt manganese oxide system electrochemical device, the electrochemical device is in an ambient temperature of -10℃ to 10℃, the unit amplitude ranges from 0.5% to 10%, and the duration of the intermittent period ranges from 10 seconds to 30 seconds; the electrochemical device is a lithium nickel cobalt manganese oxide system electrochemical device, the electrochemical device is in an ambient temperature of 10℃ to 45℃, the unit amplitude ranges from 0.5% to 10%, and the duration of the intermittent period ranges from 1 second to 10 seconds; c) The electrochemical device is a lithium cobalt oxide system electrochemical device, the electrochemical device is in an ambient temperature of -10℃ to 10℃, the unit amplitude ranges from 0.5% to 10%, and the duration of the interruption ranges from 15 seconds to 30 seconds; the electrochemical device is a lithium cobalt oxide system electrochemical device, the electrochemical device is in an ambient temperature of 10℃ to 45℃, the unit amplitude ranges from 0.5% to 10%, and the duration of the interruption ranges from 1 second to 10 seconds.

10. An electrochemical device, characterized in that, The method includes a processor and a machine-readable storage medium storing machine-executable instructions that can be executed by the processor, wherein when the processor executes the machine-executable instructions, it implements the method according to any one of claims 1-9.

11. A battery module, characterized in that, The battery module includes: at least one heating element, a management unit, and an electrochemical device, wherein, The management unit is used to perform a first charge-discharge cycle on the electrochemical device with a charging current, and to perform intermittent charging operations on the electrochemical device. During the intermittent charging operations, it acquires data related to the electrochemical device and determines the lithium plating state of charge (SOC) of the electrochemical device based on the relevant data. In addition, in response to the lithium plating SOC being less than or equal to the SOC threshold, the at least one heating element is controlled to shunt the charging current and heat the electrochemical device; The SOC threshold includes n SOC thresholds that gradually decrease from i equal to 1 to n. When i is 1 to n-1, the number of heating elements used for shunt corresponding to the i-th SOC threshold is i. The management unit is further configured to: In response to the lithium plating SOC being less than or equal to the i-th SOC threshold, the i-th heating element is controlled to shunt the charging current and heat the electrochemical device.

12. The battery module according to claim 11, characterized in that, The management unit is also used for: In response to the lithium plating SOC being less than or equal to the nth SOC threshold, the electrochemical device is controlled to stop operating; Generate a prompt message.

13. The battery module according to claim 11, characterized in that, The heating element is disposed inside the electrochemical device and / or on the outer surface of the electrochemical device.

14. The battery module according to claim 11, characterized in that, The heating element is made of at least one of nickel, nickel-aluminum alloy, copper, polyimide, silicone, or a positive temperature coefficient material; the impedance of the heating element ranges from 0.01Ω to 50Ω.

15. The battery module according to claim 11, characterized in that, The data associated with the electrochemical device includes the state of charge (SOC) and internal resistance of the electrochemical device. The intermittent charging operation includes multiple charging periods and multiple interruptions. The management unit is specifically used for: During the intermittent charging operation, for each of the plurality of intermittent periods, the SOC and internal resistance of the electrochemical device during the intermittent period are obtained. Based on the plurality of SOCs of the electrochemical device and the plurality of internal resistances of the electrochemical device corresponding to the plurality of SOCs, a first curve is obtained. The first curve is a mapping curve corresponding to the SOC and internal resistance of the electrochemical device. Based on the first curve, the state of lithium deposition (SOC) of the electrochemical device is determined.

16. The battery module according to claim 15, characterized in that, The management unit is specifically used for: Taking the first derivative of the first curve yields the second curve; and The SOC corresponding to the first point on the second curve with a negative slope is determined as the lithium plating SOC; or The second curve is obtained by taking the first derivative of the first curve; Taking the second derivative of the second curve yields the third curve; and The SOC corresponding to the point where the ordinate of the third curve first appears to be less than zero is determined as the lithium plating SOC.

17. The battery module according to claim 11, characterized in that, The intermittent charging operation includes multiple charging cycles, each charging cycle including a charging period and an intermittent period, during which the SOC of the electrochemical device increases by a unit magnitude.

18. The battery module according to claim 17, characterized in that, The electrochemical device includes at least one of a lithium iron phosphate system electrochemical device, a nickel-cobalt-manganese oxide system electrochemical device, or a lithium cobalt oxide system electrochemical device, wherein the management unit is specifically used for: The electrochemical device is a lithium iron phosphate system electrochemical device, the unit amplitude ranges from 0.5% to 10%, and the duration of the intermittent period ranges from 1 second to 15 seconds; The electrochemical device is a lithium nickel cobalt manganese oxide system electrochemical device, the unit amplitude ranges from 0.5% to 10%, and the duration of the intermittent period ranges from 1 second to 30 seconds; The electrochemical device is a lithium cobalt oxide system electrochemical device, the unit amplitude ranges from 0.5% to 10%, and the duration of the intermittent period ranges from 1 second to 30 seconds.

19. The battery module according to claim 18, characterized in that, The management unit is specifically used for any one of the following a) to c): a) The electrochemical device is a lithium iron phosphate system electrochemical device, the electrochemical device is in an ambient temperature range of -10℃ to 10℃, the unit amplitude ranges from 0.5% to 10%, and the duration of the intermittent period ranges from 5 seconds to 15 seconds; the electrochemical device is a lithium iron phosphate system electrochemical device, the electrochemical device is in an ambient temperature range of 10℃ to 45℃, the unit amplitude ranges from 0.5% to 10%, and the duration of the intermittent period ranges from 1 second to 10 seconds; b) The electrochemical device is a lithium nickel cobalt manganese oxide system electrochemical device, the electrochemical device is in an ambient temperature of -10℃ to 10℃, the unit amplitude ranges from 0.5% to 10%, and the duration of the intermittent period ranges from 10 seconds to 30 seconds; the electrochemical device is a lithium nickel cobalt manganese oxide system electrochemical device, the electrochemical device is in an ambient temperature of 10℃ to 45℃, the unit amplitude ranges from 0.5% to 10%, and the duration of the intermittent period ranges from 1 second to 10 seconds; c) The electrochemical device is a lithium cobalt oxide system electrochemical device, the electrochemical device is in an ambient temperature of -10℃ to 10℃, the unit amplitude ranges from 0.5% to 10%, and the duration of the interruption ranges from 15 seconds to 30 seconds; the electrochemical device is a lithium cobalt oxide system electrochemical device, the electrochemical device is in an ambient temperature of 10℃ to 45℃, the unit amplitude ranges from 0.5% to 10%, and the duration of the interruption ranges from 1 second to 10 seconds.

20. The battery module according to claim 11, characterized in that, Electrochemical devices belonging to the same battery module have the same electrochemical system.

21. An electrical appliance, characterized in that, Includes the battery module as described in any one of claims 11-20.

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