A method, device and readable storage medium for evaluating the cycle life of a lithium-ion battery cell

Abstract

The present invention discloses a method, device and readable storage medium for evaluating the cycle life of a lithium-supplemented battery cell. The method includes: obtaining a first cycle life and a first characteristic parameter of an un-lithium-supplemented battery cell when it cycles to the end-of-life state; obtaining a second characteristic parameter of the lithium-supplemented battery cell when it cycles to a preset battery health state; determining a second cycle life of the lithium-supplemented battery cell at the end of the consumption of the lithium supplement according to the first characteristic parameter and the second characteristic parameter; determining a third cycle life of the un-lithium-supplemented battery cell in the same first battery health state according to the second cycle life; and obtaining an evaluation cycle life of the lithium-supplemented battery cell when it cycles to the end-of-life state according to the first cycle life, the second cycle life and the third cycle life. The technical solution provided by the present invention reduces the evaluation period of the cycle life of the lithium-supplemented battery cell and improves the verification efficiency.

Description

Technical Field

[0001] The embodiments of the present invention relate to the technical field of batteries, and in particular, to a method, a device, and a readable storage medium for evaluating the cycle life of a lithium-supplemented battery cell. Background Art

[0002] Lithium supplementation in lithium-ion batteries can effectively solve the problem of the first Coulombic efficiency and improve the capacity and cycle stability of the battery. So far, various forms of prelithiation strategies have been developed, such as external electrochemical prelithiation, chemical prelithiation, lithium salt-assisted prelithiation, etc. As the cycle life of the lithium-supplemented battery cell is gradually improved, how to quickly evaluate the cycle life of the lithium-supplemented battery cell has attracted people's attention.

[0003] In the prior art, it takes a long time to cycle the lithium-supplemented battery cell to the end-of-life (EOL) state according to the cycle test conditions, and it even takes 2-3 years to evaluate. There is also a method in the prior art to establish models of characteristic parameters such as life curves, battery health (SOH), impedance, and Coulombic efficiency based on the cycle data of non-lithium-supplemented battery cells. In order to use the model to simulate and evaluate the lithium-supplemented battery cell, the lithium-supplemented battery cell needs to be cycled to a specified battery health state. For battery cells with a life of more than 10,000 cycles, this method still requires the battery cell to be cycled for nearly 1 year before simulation, which seriously affects the evaluation period and reduces the verification efficiency. Summary of the Invention

[0004] The present invention provides a method, a device, and a readable storage medium for evaluating the cycle life of a lithium-supplemented battery cell, which reduces the evaluation period of the cycle life of the lithium-supplemented battery cell and improves the verification efficiency.

[0005] In a first aspect, an embodiment of the present invention provides a method for evaluating the cycle life of a lithium-supplemented battery cell, including:

[0006] Obtaining a first cycle life and first characteristic parameters of a non-lithium-supplemented battery cell cycled to the end-of-life state;

[0007] Obtaining second characteristic parameters of the lithium-supplemented battery cell cycled to a preset battery health state;

[0008] Determining a second cycle life of the lithium-supplemented battery cell at the end of lithium-supplement agent consumption according to the first characteristic parameters and the second characteristic parameters;

[0009] Determining a third cycle life of the non-lithium-supplemented battery cell in the same first battery health state according to the second cycle life;

[0010] Obtaining an evaluation cycle life of the lithium-supplemented battery cell cycled to the end-of-life state according to the first cycle life, the second cycle life, and the third cycle life.

[0011] Optionally, obtaining the first cycle life and the first characteristic parameters of the un-lithium-supplemented battery cell until it reaches the end-of-life state includes:

[0012] Establishing a cycle curve between the state of battery health and the cycle life of the un-lithium-supplemented battery cell;

[0013] Determining the first characteristic parameters according to the cycle curve; the cycle curve includes a first non-linear attenuation stage, a first linear attenuation stage, and a second non-linear attenuation stage;

[0014] The first characteristic parameters include: the fourth cycle life and the corresponding first attenuation capacity in the first non-linear attenuation stage, the fifth cycle life and the corresponding second attenuation capacity in the first linear attenuation stage, and the sixth cycle life in the second non-linear attenuation stage;

[0015] Determining the first cycle life according to the fourth cycle life, the fifth cycle life, and the sixth cycle life.

[0016] Optionally, determining the second cycle life of the lithium-supplemented battery cell at the end of lithium-supplement consumption according to the first characteristic parameters and the second characteristic parameters includes:

[0017] Setting the second cycle life as an unknown variable;

[0018] Expressing the attenuation capacity of the un-lithium-supplemented battery cell at the second cycle life according to the first characteristic parameters and the unknown variable;

[0019] Expressing the total capacity increased by the lithium-supplement for the lithium-supplemented battery cell according to the second characteristic parameters and the variable;

[0020] Obtaining the second cycle life according to the equality relationship between the attenuation capacity of the un-lithium-supplemented battery cell at the second cycle life and the total capacity increased by the lithium-supplement for the lithium-supplemented battery cell.

[0021] Optionally, the first characteristic parameters further include the first attenuation rate in the first linear attenuation stage and the first charging capacity of the un-lithium-supplemented battery cell; the second characteristic parameters include the second attenuation rate of the lithium-supplemented battery cell until it reaches the preset state of battery health and the first charging capacity of the lithium-supplemented battery cell;

[0022] The obtaining the second cycle life according to the equality relationship between the attenuation capacity of the un-lithium-supplemented battery cell at the second cycle life and the total capacity increased by the lithium-supplement for the lithium-supplemented battery cell includes:

[0023] The attenuation capacity of the un-lithium-supplemented battery cell at the second cycle life is: q1 + (X - U1) * k1;

[0024] The total capacity increased by the lithium supplementing agent for the lithium supplementing battery cell is: X*k2+(Q2-Q1);

[0025] Obtain the second cycle life according to the formula X*k2+(Q2-Q1) = q1+(X-U1)*k1;

[0026] Wherein, X is an unknown quantity of the assumed second cycle life; U1 is the first cycle life; q1 is the first attenuation capacity; k1 is the first attenuation rate; k2 is the second attenuation rate; Q1 is the first charge capacity of the non-lithium-supplemented battery cell; Q2 is the first charge capacity of the lithium-supplemented battery cell.

[0027] Optionally, obtaining the evaluation cycle life of the lithium-supplemented battery cell when it cycles to the end-of-life state according to the first cycle life, the second cycle life and the third cycle life includes:

[0028] Evaluate the cycle life of the lithium-supplemented battery cell after the consumption of the lithium supplementing agent according to the first cycle life and the third cycle life;

[0029] Obtain the evaluation cycle life of the lithium-supplemented battery cell when it cycles to the end-of-life state according to the second cycle life and the cycle life of the lithium-supplemented battery cell after the consumption of the lithium supplementing agent.

[0030] Optionally, obtaining the evaluation cycle life of the lithium-supplemented battery cell when it cycles to the end-of-life state according to the second cycle life and the cycle life of the lithium-supplemented battery cell after the consumption of the lithium supplementing agent includes:

[0031] Calculate and obtain the evaluation cycle life through a calculation formula, wherein the calculation formula is:

[0032] Z = U - Y + X; wherein, Z is the evaluation cycle life; U is the first cycle life; Y is the third cycle life; X is the second cycle life.

[0033] Optionally, the end-of-life state is 80%-60% of the factory-capacity of the current battery cell.

[0034] Optionally, the preset battery health state is 98%-90% of the factory-capacity of the current battery cell.

[0035] In a second aspect, an embodiment of the present invention provides a device for evaluating the cycle life of a lithium-supplemented battery cell, including:

[0036] A first acquisition unit, configured to acquire a first cycle life and a first characteristic parameter of a non-lithium-supplemented battery cell when it cycles to the end-of-life state;

[0037] A second acquisition unit, configured to acquire a second characteristic parameter of the lithium-supplemented battery cell when it cycles to the preset battery health state;

[0038] A first calculation unit, configured to determine a second cycle life of the lithium - supplemented battery cell at the end of the consumption of the lithium - supplementing agent according to the first characteristic parameter and the second characteristic parameter; and determine a first battery health state corresponding to the lithium - supplemented battery cell according to the second cycle life;

[0039] A second calculation unit, configured to determine a third cycle life of the non - lithium - supplemented battery cell in the first battery health state;

[0040] A third calculation unit, configured to obtain an estimated cycle life of the lithium - supplemented battery cell until it reaches the end - of - life state according to the first cycle life, the second cycle life, and the third cycle life.

[0041] In a third aspect, an embodiment of the present invention provides a computer - readable storage medium storing computer instructions, and the computer instructions are used to cause a processor to implement the method for evaluating the cycle life of a lithium - supplemented battery cell provided in any item of the embodiments of the present invention when executed.

[0042] The technical solution provided by the embodiment of the present invention obtains the first cycle life and the first characteristic parameter of the non - lithium - supplemented battery cell until it reaches the end - of - life state, and obtains the second characteristic parameter by cycling the lithium - supplemented battery cell to a preset battery health state. By using the relationship between the capacity increased by the lithium - supplementing agent and the capacity attenuation of the non - lithium - supplemented battery cell, the second cycle life of the lithium - supplemented battery cell at the end of the consumption of the lithium - supplementing agent is determined according to the first characteristic parameter and the second characteristic parameter. Further, the third cycle life of the non - lithium - supplemented battery cell in the same first battery health state is determined according to the second cycle life. The relationship between the first cycle life and the third cycle life during the attenuation process of the non - lithium - supplemented battery cell is used to characterize the number of cycles provided after the consumption of the lithium - supplementing agent of the lithium - supplemented battery cell. Then, the estimated cycle life of the lithium - supplemented battery cell until it reaches the end - of - life state is obtained by combining the second cycle life. Since the lithium - supplemented battery cell is in a linear attenuation stage in the early stage of cycle attenuation, using this linear attenuation stage combined with the attenuation process of the non - lithium - supplemented battery cell for evaluation can reduce the number of test times of the lithium - supplemented battery cell during cycle attenuation, meet the evaluation requirements, reduce the evaluation period, and improve the verification efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 It is a schematic flowchart of a method for evaluating the cycle life of a lithium - supplemented battery cell provided by an embodiment of the present invention;

[0044] Figure 2 It is another schematic flowchart of a method for evaluating the cycle life of a lithium - supplemented battery cell provided by an embodiment of the present invention;

[0045] Figure 3 It is a schematic diagram of a cycle curve provided by an embodiment of the present invention;

[0046] Figure 4 This is a schematic structural diagram of another device for evaluating the cycle life of a lithium - supplemented battery cell provided by an embodiment of the present invention. Detailed implementation manners

[0047] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0048] In the prior art, the lithium - supplemented battery cells are tested according to cycle test conditions. For example, in the test standard, it is required to cycle at a conventional rate of 0.2C for 500 times, and the battery capacity shall not be less than 80% of the rated capacity. However, to complete 500 tests, taking a 1000 mAh battery as an example, it takes at least 7 months, which is time - consuming. There is also a method of establishing a data model through the cycle data of non - lithium - supplemented battery cells and predicting the cycle life of lithium - supplemented battery cells through the data model. However, to ensure the prediction accuracy, it is usually necessary to cycle the lithium - supplemented battery cells to an SOH of less than 90%. For lithium - supplemented battery cells, this method still requires the battery cells to cycle for a long time before simulation can be carried out, seriously affecting the evaluation period and reducing the verification efficiency.

[0049] In view of this, Figure 1 This is a schematic flowchart of a method for evaluating the cycle life of a lithium - supplemented battery cell provided by an embodiment of the present invention. This embodiment is applicable to the evaluation of the cycle life of lithium - supplemented battery cells. This method can be executed by a device for evaluating the cycle life of lithium - supplemented battery cells, and the device can be implemented in a hardware and / or software manner. The method specifically includes the following steps:

[0050] S110. Obtain the first cycle life and the first characteristic parameter of the non - lithium - supplemented battery cell when it cycles to the end - of - life state;

[0051] Specifically, the end - of - life (EOL) state refers to the state when the battery capacity decays to a preset percentage of the factory - installed capacity. Exemplarily, the EOL state can be the state of 80% - 60% of the factory - installed capacity, that is, 80% - 60% of the state of health (SOH) of the battery.

[0052] Perform a cycle life test on the uncompensated lithium battery cells to obtain the first cycle life of the uncompensated lithium battery cells until they reach the EOL state. The first cycle life refers to the total cycle life of the uncompensated lithium battery cells. Exemplarily, the cycle life can be characterized by the number of cycles. According to the cycle test process of the uncompensated lithium battery cells, the first characteristic parameters can be extracted. The first characteristic parameters include parameters such as the first charge capacity of the uncompensated lithium battery cells, the number of cycles in the first non-linear attenuation stage and the corresponding attenuation capacity, the number of cycles in the linear attenuation stage, the corresponding attenuation capacity, and the linear attenuation rate in the linear attenuation stage.

[0053] S120. Obtain the second characteristic parameters of the compensated lithium battery cells when they reach the preset battery health state;

[0054] Specifically, perform a cycle test on the compensated lithium battery cells until they reach the preset battery health state. Since the compensated lithium battery cells are in the linear attenuation stage in the early stage of cycle attenuation, the preset battery health can be selected to attenuate to 98%-90% of the SOH in the linear attenuation stage, and the corresponding second characteristic parameters can be obtained, reducing the cycle period of the compensated lithium battery cell test. Among them, the second characteristic parameters include parameters such as the first charge capacity of the compensated lithium battery cells and the attenuation rate in the linear attenuation stage of the compensated lithium battery cells.

[0055] S130. Determine the second cycle life of the compensated lithium battery cells at the end of the consumption of the lithium compensator according to the first characteristic parameters and the second characteristic parameters;

[0056] Specifically, the compensated lithium battery cells are at the end of the linear attenuation stage at the end of the consumption of the lithium compensator. Obtain the total capacity provided by the lithium compensator according to the second characteristic parameters. Obtain the attenuation capacity of the uncompensated lithium battery cells at the corresponding second cycle life according to the first characteristic parameters. Since the total capacity provided by the lithium compensator has an equal mathematical relationship with the attenuation capacity of the uncompensated lithium battery cells at the corresponding second cycle life, a mathematical model can be established with the second cycle life as the unknown variable according to this mathematical relationship, and the second cycle life of the compensated lithium battery cells at the end of the consumption of the lithium compensator can be obtained. Exemplarily, the attenuation capacity can be obtained according to the second cycle life and the attenuation rate in the linear attenuation stage of the compensated lithium battery cells, and the capacity increased by lithium compensation can be obtained according to the first charge capacity of the uncompensated lithium battery cells and the first charge capacity of the compensated lithium battery cells. Therefore, the total capacity provided by the lithium compensator can be obtained according to the attenuation capacity and the capacity increased by lithium compensation. The attenuation capacity of the uncompensated lithium battery cells at the corresponding second cycle life can be expressed by the number of cycles in the first non-linear attenuation stage, the corresponding attenuation capacity, the linear attenuation rate in the linear attenuation stage, and the second cycle life. Further, the second cycle life can be obtained according to the equation relationship.

[0057] S140. Determine the third cycle life of the uncompensated lithium battery cells in the same first battery health state according to the second cycle life;

[0058] Specifically, the SOH of the lithium - supplemented battery cell at this time can be determined according to the second cycle life. Corresponding to the attenuation process of the lithium - supplemented battery cell at this time, the third cycle life of the non - lithium - supplemented battery cell when it decays to this SOH can be obtained according to the attenuation process of the non - lithium - supplemented battery cell.

[0059] S150. Obtain the evaluation cycle life of the lithium - supplemented battery cell when it cycles to the end - of - life state according to the first cycle life, the second cycle life, and the third cycle life.

[0060] Specifically, the second cycle life is the number of cycles provided when the lithium supplement agent consumption ends during the attenuation process of the lithium - supplemented battery cell, and the third cycle life is the number of cycles for evaluating the SOH of the non - lithium - supplemented battery cell when it decays to the SOH at the end of lithium supplement agent consumption during the attenuation process of the non - lithium - supplemented battery cell. During the attenuation process of the non - lithium - supplemented battery cell, combining the first cycle life of the non - lithium - supplemented battery cell, subtracting the third cycle life from the first cycle life represents the number of cycles provided after the lithium supplement agent consumption of the lithium - supplemented battery cell ends. Then, combining with the number of cycles provided at the end of lithium supplement agent consumption, that is, the second cycle life, the evaluation cycle life of the lithium - supplemented battery cell when it cycles to the end - of - life state can be obtained.

[0061] The technical solution provided in the embodiments of the present invention obtains the first cycle life and the first characteristic parameter of the non - lithium - supplemented battery cell when it cycles to the end - of - life state, and obtains the second characteristic parameter when the lithium - supplemented battery cell cycles to the preset battery health state. By using the relationship between the capacity increased by the lithium supplement agent and the attenuation capacity of the non - lithium - supplemented battery cell, the second cycle life of the lithium - supplemented battery cell at the end of lithium supplement agent consumption is determined according to the first characteristic parameter and the second characteristic parameter. And further, according to the second cycle life, the third cycle life of the non - lithium - supplemented battery cell in the same first battery health state is determined. Using the relationship between the first cycle life and the third cycle life during the attenuation process of the non - lithium - supplemented battery cell to represent the number of cycles provided after the lithium supplement agent consumption of the lithium - supplemented battery cell ends, and then combining with the second cycle life, the evaluation cycle life of the lithium - supplemented battery cell when it cycles to the end - of - life state is obtained. Since the lithium - supplemented battery cell is in a linear attenuation stage in the early stage of cyclic attenuation, using this linear attenuation stage combined with the attenuation process of the non - lithium - supplemented battery cell for evaluation can reduce the number of cyclic attenuation tests of the lithium - supplemented battery cell, that is, it can meet the evaluation requirements, thereby reducing the evaluation period and improving the verification efficiency.

[0062] Figure 2 For another method flow diagram for evaluating the cycle life of a lithium - supplemented battery cell provided by an embodiment of the present invention, see Figure 2 , including:

[0063] S210. Establish a cycle curve between the battery health state and the cycle life of the non - lithium - supplemented battery cell;

[0064] Specifically, obtain the test data of the non - lithium - supplemented battery cell according to the cycle life test standard, and establish a cycle curve between the battery health state (SOH) and the cycle life of the non - lithium - supplemented battery cell according to the test data.Figure 3 A schematic diagram of a cycling curve provided by an embodiment of the present invention is shown in Figure 3 , where the solid line is the cycling curve of the un-lithium-supplemented battery cell, and the dashed line is the cycling curve of the lithium-supplemented battery cell. The cycling curve of the un-lithium-supplemented battery cell can be divided into three stages: the first non-linear attenuation stage a, the first linear attenuation stage b, and the second non-linear attenuation stage c.

[0065] S220. Determine the first characteristic parameter according to the cycling curve;

[0066] Among them, the corresponding first characteristic parameter can be obtained according to the test data and the cycling curve. For example, the number of cycling cycles (the fourth cycling life U1) and the corresponding attenuation capacity (the first attenuation capacity q1) in the first non-linear attenuation stage. Parameters such as the number of cycling cycles (the fifth cycling life U2), the corresponding attenuation capacity (the second attenuation capacity q2), and the first attenuation rate k1 in the first linear attenuation stage; among them, the first linear attenuation rate k1 is the ratio of the second attenuation capacity q2 to the fifth cycling life U2. The number of cycling cycles (the sixth cycling life U3) in the second non-linear attenuation stage. The first cycling life is the sum of the fourth cycling life U1, the fifth cycling life U2, and the sixth cycling life U3. By the first charging of the un-lithium-supplemented battery cell, the first charging capacity can be obtained.

[0067] S230. Obtain the second characteristic parameter when the lithium-supplemented battery cell is cycled to the preset state of battery health;

[0068] Specifically, the lithium-supplemented battery cell is cycled until it reaches the preset state of battery health. According to the test data, a cycling curve between the state of battery health (SOH) and the cycling life can be established. Since the lithium-supplemented battery cell is in a linear attenuation stage in the early stage of cycling attenuation, therefore, the preset state of battery health can be exemplarily selected as the SOH attenuated to 98%-90% in the linear attenuation stage, and the corresponding second characteristic parameter can be obtained, such as parameters such as the attenuation rate (the second attenuation rate k2) in the linear attenuation stage of the lithium-supplemented battery cell. Similarly, the first charging capacity is obtained by the first charging of the lithium-supplemented battery cell.

[0069] S240. Determine the second cycling life of the lithium-supplemented battery cell at the end of the consumption of the lithium supplement according to the first characteristic parameter and the second characteristic parameter;

[0070] S250. Determine the third cycling life of the un-lithium-supplemented battery cell in the same first state of battery health according to the second cycling life;

[0071] S260. Obtain the evaluation cycling life of the lithium-supplemented battery cell cycled to the end-of-life state according to the first cycling life, the second cycling life, and the third cycling life.

[0072] Based on the above embodiments, continue to refer to Figure 3, optionally, determining the second cycle life of the lithium supplement cell at the end of lithium supplement consumption according to the first characteristic parameter and the second characteristic parameter includes:

[0073] Let the second cycle life be an unknown quantity;

[0074] Express the attenuation capacity of the non-lithium-supplemented cell at the second cycle life according to the first characteristic parameter and the unknown quantity;

[0075] Express the total capacity increased by the lithium supplement for the lithium supplement cell according to the second characteristic parameter and the variable;

[0076] Obtain the second cycle life according to the equality relationship between the attenuation capacity of the non-lithium-supplemented cell at the second cycle life and the total capacity increased by the lithium supplement for the lithium supplement cell.

[0077] Specifically, since there is an equal mathematical relationship between the total capacity provided by the lithium supplement and the attenuation capacity of the non-lithium-supplemented cell at the corresponding second cycle life, a mathematical model can be established with the second cycle life as the unknown variable according to this mathematical relationship, and the second cycle life of the lithium supplement cell at the end of lithium supplement consumption can be obtained.

[0078] Assume that the second cycle life is X. According to the second cycle life being X and the second attenuation rate k2 of the lithium supplement cell, the attenuation capacity can be obtained. According to the first charge capacity Q1 of the non-lithium-supplemented cell and the first charge capacity Q2 of the lithium supplement cell, the capacity increased by lithium supplement is obtained. Therefore, the total capacity provided by the lithium supplement is obtained according to the attenuation capacity and the capacity increased by lithium supplement. The attenuation capacity of the non-lithium-supplemented cell at the corresponding second cycle life can be expressed by the number of cycles (the fourth cycle life U1) in the first non-linear attenuation stage, the corresponding attenuation capacity (the first attenuation capacity q1), the first attenuation rate k1 in the linear attenuation stage, and the second cycle life X. Further, the second cycle life can be obtained according to the equality relationship.

[0079] Optionally, obtaining the second cycle life according to the equality relationship between the attenuation capacity of the non-lithium-supplemented cell at the second cycle life and the total capacity increased by the lithium supplement for the lithium supplement cell can be expressed as:

[0080] X*k2+(Q2-Q1)=q1+(X-U1)*k1;

[0081] Among them, X is the unknown quantity of the assumed second cycle life; U1 is the first cycle life; q1 is the first attenuation capacity; k1 is the first attenuation rate; k2 is the second attenuation rate; Q1 is the first charge capacity of the non-lithium-supplemented cell; Q2 is the first charge capacity of the lithium supplement cell, and thus X can be obtained.

[0082] Based on the above embodiments, refer to Figure 3, optionally, obtaining an estimated cycle life Z of the compensated lithium battery cell cycling to the end-of-life state based on the first cycle life U, the second cycle life X, and the third cycle life Y, includes:

[0083] Evaluating the cycle life of the compensated lithium battery cell after the consumption of the lithium supplement agent based on the first cycle life U and the third cycle life Y;

[0084] Obtaining the estimated cycle life Z of the compensated lithium battery cell cycling to the end-of-life state according to the second cycle life X and the cycle life of the compensated lithium battery cell after the consumption of the lithium supplement agent.

[0085] Specifically, the second cycle life X is the number of cycles provided when the consumption of the lithium supplement agent ends, and the third cycle life Y is the number of cycles for evaluating the attenuation process of the non-compensated lithium battery cell until the SOH of the non-compensated lithium battery cell decays to that at the end of the consumption of the lithium supplement agent. During the attenuation process of the non-compensated lithium battery cell, combining the first cycle life U of the non-compensated lithium battery cell, subtracting the third cycle life Y from the first cycle life U represents the number of cycles provided after the consumption of the lithium supplement agent of the compensated lithium battery cell. Then, combining the number of cycles provided at the end of the consumption of the lithium supplement agent, i.e., the second cycle life X, the estimated cycle life Z of the compensated lithium battery cell cycling to the end-of-life state can be obtained. Optionally, obtaining the estimated cycle life of the compensated lithium battery cell cycling to the end-of-life state according to the second cycle life and the cycle life of the compensated lithium battery cell after the consumption of the lithium supplement agent, includes:

[0086] Calculating the estimated cycle life through a calculation formula, where the calculation formula is:

[0087] Z = U - Y + X;

[0088] where, Z is the estimated cycle life; U is the first cycle life; Y is the third cycle life; X is the second cycle life.

[0089] Optionally, the end-of-life state is 80% - 60% of the factory capacity of the current battery cell. That is, when the non-compensated lithium battery cell and the compensated lithium battery cell reach 80% - 60% SOH, it is considered to reach the end-of-life (EOL) state.

[0090] Optionally, in obtaining the second characteristic parameter of the compensated lithium battery cell cycling to the preset battery health state, the preset battery health state can be 98% - 90% of the factory capacity of the current battery cell. That is, cycling the compensated lithium battery cell to 98% - 90% SOH can complete the evaluation. Compared with the prior art where the non-compensated lithium battery cell needs to be cycled to below 90% SOH, the evaluation period is greatly reduced and the verification efficiency is improved.

[0091] Figure 4 Schematic diagram of the structure of another device for evaluating the cycle life of a compensated lithium battery cell provided by an embodiment of the present invention, see Figure 4 , includes:

[0092] The first acquisition unit 110 is configured to acquire the first cycle life and the first characteristic parameters of the un-lithium-supplemented battery cell when it is cycled to the end-of-life state.

[0093] The second acquisition unit 120 is configured to acquire the second characteristic parameters of the lithium-supplemented battery cell when it is cycled to the preset battery health state.

[0094] The first calculation unit 130 is configured to determine the second cycle life of the lithium-supplemented battery cell at the end of the consumption of the lithium supplement according to the first characteristic parameters and the second characteristic parameters; and determine the first battery health state corresponding to the lithium-supplemented battery cell according to the second cycle life.

[0095] The second calculation unit 140 is configured to calculate the third cycle life of the un-lithium-supplemented battery cell in the first battery health state;

[0096] The third calculation unit 150 is configured to obtain the estimated cycle life of the lithium-supplemented battery cell when it is cycled to the end-of-life state according to the first cycle life, the second cycle life, and the third cycle life.

[0097] Specifically, the first acquisition unit 110 performs a cycle life test on the un-lithium-supplemented battery cell to obtain the first cycle life of the un-lithium-supplemented battery cell when it is cycled to the EOL state. Here, the first cycle life refers to the total cycle life of the un-lithium-supplemented battery cell. Exemplarily, the cycle life can be characterized by the number of cycles. The first acquisition unit can extract the first characteristic parameters according to the cycle test process of the un-lithium-supplemented battery cell. The first characteristic parameters include parameters such as the first charging capacity of the un-lithium-supplemented battery cell, the number of cycles in the first non-linear attenuation stage and the corresponding attenuation capacity, the number of cycles in the linear attenuation stage, the corresponding attenuation capacity, and the linear attenuation rate in the linear attenuation stage.

[0098] The second acquisition unit 120 performs a cycle test on the lithium-supplemented battery cell until it reaches the preset battery health state. Since the lithium-supplemented battery cell is in the linear attenuation stage in the early stage of cycle attenuation, the preset battery health can be selected to attenuate to 98%-90% of the SOH in the linear attenuation stage, and the corresponding second characteristic parameters can be obtained, thereby reducing the cycle period of the lithium-supplemented battery cell test. The second characteristic parameters include parameters such as the first charging capacity of the lithium-supplemented battery cell and the attenuation rate in the linear attenuation stage of the lithium-supplemented battery cell.

[0099] When the consumption of the lithium supplement of the lithium-supplemented battery cell ends, it is at the end stage of the linear attenuation of the lithium-supplemented battery cell. The first calculation unit 130 obtains the total capacity provided by the lithium supplement according to the second characteristic parameters, and obtains the attenuation capacity of the un-lithium-supplemented battery cell at the corresponding second cycle life according to the first characteristic parameters. Since the total capacity provided by the lithium supplement has an equal mathematical relationship with the attenuation capacity of the un-lithium-supplemented battery cell at the corresponding second cycle life, a mathematical model can be established with the second cycle life as the unknown variable according to this mathematical relationship, and the second cycle life of the lithium-supplemented battery cell at the end of the consumption of the lithium supplement can be obtained.

[0100] The second calculation unit 140 can determine the SOH at which the supplementary lithium battery cell is attenuated according to the second cycle life. Corresponding the SOH at which it is attenuated at this time to the attenuation process of the non-supplementary lithium battery cell, the third cycle life of the non-supplementary lithium battery cell when it is attenuated to this SOH can be obtained.

[0101] During the attenuation process of the non-supplementary lithium battery cell, the third calculation unit 150 combines the first cycle life of the non-supplementary lithium battery cell, subtracts the third cycle life from the first cycle life to represent the number of cycles provided after the consumption of the lithium supplement agent in the supplementary lithium battery cell ends, and then combines the number of cycles provided at the end of the consumption of the lithium supplement agent, that is, the second cycle life, to obtain the evaluation cycle life of the supplementary lithium battery cell when it cycles to the end-of-life state.

[0102] In some embodiments, the method for evaluating the cycle life of a supplementary lithium battery cell can be implemented as a computer program, which is tangibly included in a computer-readable storage medium, such as a storage unit. In some embodiments, part or all of the computer program can be loaded and / or installed onto the corresponding electronic device via the ROM and / or the communication unit. When the computer program is loaded into the RAM and executed by the processor, one or more steps of the method for evaluating the cycle life of the supplementary lithium battery cell described above can be executed. Alternatively, in other embodiments, the processor can be configured to execute the method for evaluating the cycle life of the supplementary lithium battery cell by any other suitable means (for example, by means of firmware).

[0103] A computer-readable storage medium can be a tangible medium that can contain or store a computer program for use by or in connection with an instruction execution system, apparatus, or device. A computer-readable storage medium can include, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatus, or devices, or any suitable combination of the foregoing. Alternatively, a computer-readable storage medium can be a machine-readable signal medium. More specific examples of a machine-readable storage medium would include an electrical connection based on one or more wires, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0104] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features. These modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for evaluating the cycle life of a lithium-ion battery cell, characterized in that Including: Obtaining a first cycle life and a first characteristic parameter of an un-lithium-supplemented battery cell when it is cycled to the end-of-life state; Obtaining a second characteristic parameter of the lithium-supplemented battery cell when it is cycled to a preset battery health state; Determining a second cycle life of the lithium-supplemented battery cell at the end of lithium-supplement consumption according to the first characteristic parameter and the second characteristic parameter; Determining a third cycle life of the un-lithium-supplemented battery cell at the same first battery health state according to the second cycle life; Obtaining an evaluation cycle life of the lithium-supplemented battery cell when it is cycled to the end-of-life state according to the first cycle life, the second cycle life and the third cycle life.

2. The method for evaluating the cycle life of a supplementary lithium battery cell according to claim 1, wherein The obtaining of the first cycle life and the first characteristic parameter of the un-lithium-supplemented battery cell when it is cycled to the end-of-life state includes: Establishing a cycle curve between the battery health state and the cycle life of the un-lithium-supplemented battery cell; Determining the first characteristic parameter according to the cycle curve; the cycle curve includes a first non-linear attenuation stage, a first linear attenuation stage and a second non-linear attenuation stage; The first characteristic parameter includes: a fourth cycle life and a corresponding first attenuation capacity in the first non-linear attenuation stage, a fifth cycle life and a corresponding second attenuation capacity in the first linear attenuation stage, and a sixth cycle life in the second non-linear attenuation stage; Determining the first cycle life according to the fourth cycle life, the fifth cycle life and the sixth cycle life.

3. The method for evaluating the cycle life of a supplementary lithium battery cell according to claim 2, characterized in that, The determining of the second cycle life of the lithium-supplemented battery cell at the end of lithium-supplement consumption according to the first characteristic parameter and the second characteristic parameter includes: Setting the second cycle life as an unknown quantity; Expressing the attenuation capacity of the un-lithium-supplemented battery cell at the second cycle life according to the first characteristic parameter and the unknown quantity; Expressing the total capacity increased by the lithium-supplement for the lithium-supplemented battery cell according to the second characteristic parameter, the first characteristic parameter and the unknown quantity; Obtaining the second cycle life according to the equality relationship between the attenuation capacity of the un-lithium-supplemented battery cell at the second cycle life and the total capacity increased by the lithium-supplement for the lithium-supplemented battery cell.

4. The method for evaluating the cycle life of a supplementary lithium battery cell according to claim 3, characterized in that, The first characteristic parameter further includes a first attenuation rate in the first linear attenuation stage and the first charging capacity of the un-lithium-supplemented battery cell; the second characteristic parameter includes a second attenuation rate of the lithium-supplemented battery cell when it is cycled to the preset battery health state and the first charging capacity of the lithium-supplemented battery cell; The obtaining of the second cycle life according to the equality relationship between the attenuation capacity of the un-lithium-supplemented battery cell at the second cycle life and the total capacity increased by the lithium-supplement for the lithium-supplemented battery cell includes: The attenuation capacity of the un-lithium-supplemented battery cell at the second cycle life is: q1+(X - U1)*k1; The total capacity increased by the lithium-supplement for the lithium-supplemented battery cell is: X*k2+(Q2 - Q1); Obtaining the second cycle life according to the formula X*k2+(Q2 - Q1)=q1+(X - U1)*k1; Wherein, X is an unknown quantity of the assumed second cycle life; U1 is the first cycle life; q1 is the first attenuation capacity; k1 is the first attenuation rate; k2 is the second attenuation rate; Q1 is the first charging capacity of the uncompensated lithium battery cell; Q2 is the first charging capacity of the compensated lithium battery cell.

5. The method for evaluating the cycle life of a supplementary lithium battery cell according to claim 1, characterized in that, Obtaining the evaluation cycle life of the compensated lithium battery cell when it cycles to the end-of-life state according to the first cycle life, second cycle life, and third cycle life includes: Evaluating the cycle life of the compensated lithium battery cell after the consumption of the lithium compensation agent according to the first cycle life and the third cycle life; Obtaining the evaluation cycle life of the compensated lithium battery cell when it cycles to the end-of-life state according to the second cycle life and the cycle life of the compensated lithium battery cell after the consumption of the lithium compensation agent.

6. The method for evaluating the cycle life of a supplementary lithium battery cell according to claim 5, wherein Obtaining the evaluation cycle life of the compensated lithium battery cell when it cycles to the end-of-life state according to the second cycle life and the cycle life of the compensated lithium battery cell after the consumption of the lithium compensation agent includes: Calculating to obtain the evaluation cycle life through a calculation formula, wherein the calculation formula is: Z = U - Y + X; where Z is the evaluation cycle life; U is the first cycle life; Y is the third cycle life; X is the second cycle life.

7. The method for evaluating the cycle life of a supplementary lithium battery cell according to any one of claims 1-6, characterized in that, The end-of-life state is 80% - 60% of the factory-rated capacity of the current battery cell.

8. The method for evaluating the cycle life of a lithium-ion battery cell according to any one of claims 1-6, characterized in that The preset battery health state is 98% - 90% of the factory-rated capacity of the current battery cell.

9. A device for evaluating the cycle life of a lithium-ion battery cell, characterized in that, Including: A first acquisition unit for acquiring the first cycle life and the first characteristic parameters of the uncompensated lithium battery cell when it cycles to the end-of-life state; A second acquisition unit for acquiring the second characteristic parameters of the compensated lithium battery cell when it cycles to the preset battery health state; A first calculation unit for determining the second cycle life of the compensated lithium battery cell at the end of the consumption of the lithium compensation agent according to the first characteristic parameters and the second characteristic parameters; And determining the corresponding first battery health state of the compensated lithium battery cell according to the second cycle life; A second calculation unit for calculating the third cycle life of the uncompensated lithium battery cell in the first battery health state; A third calculation unit for obtaining the evaluation cycle life of the compensated lithium battery cell when it cycles to the end-of-life state according to the first cycle life, second cycle life, and third cycle life.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer instructions, and the computer instructions are used to cause the processor to implement the method for evaluating the cycle life of the compensated lithium battery cell according to any one of claims 1 - 8 when executed.

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