Lithium precipitation detection method of lithium ion battery, computer equipment, medium and vehicle

Abstract

The invention relates to the technical field of lithium ion batteries, particularly provides a lithium precipitation detection method of a lithium ion battery, computer equipment, a medium and a vehicle, and aims to solve the problem of realizing high-precision lithium precipitation detection on the basis of not changing the structure of a battery pack. In order to achieve the purpose, the method provided by the invention comprises the following steps: acquiring actual terminal voltage of each battery cell in the lithium ion battery after charging is cut off and actual relaxation time when the actual terminal voltage is acquired; acquiring an actual health state and an actual charging condition of the lithium ion battery; based on the actual health state and the actual charging condition, obtaining a theoretical terminal voltage when the relaxation time reaches the actual relaxation time after the charging of each battery cell is cut off under the condition that lithium precipitation does not occur; and according to the actual terminal voltage and the theoretical terminal voltage, judging whether lithium precipitation occurs in the cell. Through the method, whether lithium precipitation occurs or not can be accurately judged whether the lithium precipitation is slight or serious; and meanwhile, the structure of the lithium ion battery does not need to be transformed.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium ion batteries, and in particular to a lithium deposition detection method, computer equipment, medium and vehicle for lithium ion batteries. Background Art

[0002] When lithium deposition occurs in lithium-ion batteries, the content of active lithium ions in the battery will be greatly reduced, causing a sharp decrease in battery capacity. The lithium metal formed by the deposited lithium ions may even puncture the battery separator, causing a short circuit between the positive and negative poles of the battery, posing a serious safety risk.

[0003] At present, the lithium deposition detection method of lithium-ion batteries mainly includes the detection using the characteristics generated after lithium deposition. For example, if the differential curve of the static voltage over time after charging is cut off has a concave peak, it is determined that lithium deposition has occurred; or the detection method can also include the detection using the thickness of the negative electrode after lithium deposition (lithium dendrites formed by lithium deposition will cause the thickness of the negative electrode to increase). However, the method of detection using the characteristics generated after lithium deposition cannot distinguish a slight degree of lithium deposition. The method of detection using the thickness of the negative electrode after lithium deposition requires the installation of an additional pressure sensor on the outside of the battery cell, which will not only significantly increase the cost of the battery, but may also affect the heat dissipation effect and threaten the safety of the battery.

[0004] Accordingly, the art needs a new technical solution to solve the above problems. Summary of the invention

[0005] In order to overcome the above-mentioned defects, the present invention is proposed to provide a lithium ion battery lithium deposition detection method, computer equipment, medium and vehicle that solves or at least partially solves the technical problem of how to achieve high-precision lithium deposition detection without changing the battery pack structure.

[0006] In a first aspect, a method for detecting lithium deposition in a lithium ion battery is provided, the method comprising:

[0007] Obtaining the actual terminal voltage of each cell in the lithium-ion battery after charging is terminated and the actual relaxation time when the actual terminal voltage is obtained;

[0008] Obtaining the actual health status and actual charging condition of the lithium-ion battery;

[0009] Based on the actual health state and the actual charging condition, obtaining a theoretical terminal voltage when the relaxation time after charging of each battery cell is terminated reaches the actual relaxation time without lithium plating;

[0010] Whether lithium deposition occurs in the battery cell is determined according to the actual terminal voltage and the theoretical terminal voltage.

[0011] In one technical solution of the above-mentioned lithium ion battery lithium deposition detection method, obtaining the theoretical terminal voltage includes:

[0012] Based on the actual health state and the actual charging condition, obtaining a theoretical open circuit voltage and theoretical characteristic parameters of the battery cell after charging is terminated without lithium plating;

[0013] Based on the RC equivalent circuit model of the battery cell and according to the theoretical open circuit voltage, the theoretical characteristic parameter and the actual relaxation time, obtaining the theoretical terminal voltage of the battery cell;

[0014] Wherein, the theoretical characteristic parameters include ohmic internal resistance, polarization internal resistance and polarization capacitance.

[0015] In a technical solution of the above-mentioned lithium ion battery lithium deposition detection method, the actual charging condition includes the actual charging temperature, and obtaining the theoretical open circuit voltage includes:

[0016] Acquire first calibration data between a preset health state, a charging temperature, and an open circuit voltage;

[0017] The theoretical open circuit voltage is obtained based on the first calibration data and according to the actual health state and the actual charging temperature.

[0018] In a technical solution of the above-mentioned lithium ion battery lithium plating detection method, the first calibration data is obtained by the following method:

[0019] Obtain the actual open circuit voltage of the battery cell when the lithium-ion battery is fully charged under different preset health states and different preset charging temperatures;

[0020] The first calibration data is acquired according to the preset health state, the preset charging temperature and the actual open circuit voltage.

[0021] In a technical solution of the above-mentioned lithium deposition detection method for lithium ion batteries, the actual charging conditions include actual charging temperature and actual charging current, and obtaining the theoretical characteristic parameters includes:

[0022] Acquire second calibration data between preset health status, charging temperature, charging current and characteristic parameters;

[0023] The theoretical characteristic parameter is obtained based on the second calibration data and in accordance with the actual health state, the actual charging temperature and the actual charging current.

[0024] In a technical solution of the above-mentioned lithium ion battery lithium plating detection method, the second calibration data is obtained by the following method:

[0025] Respectively obtain the relaxation voltage of the lithium-ion battery after charging is cut off under different preset health states, different preset charging temperatures and different preset charging currents;

[0026] Based on the RC equivalent circuit model of the battery cell and according to the relaxation voltage, obtaining actual characteristic parameters of the battery cell;

[0027] The second calibration data is acquired according to the preset health state, the preset charging current, the preset charging temperature and the actual characteristic parameter.

[0028] In a technical solution of the above-mentioned lithium ion battery lithium deposition detection method, obtaining the actual charging current includes:

[0029] If the lithium-ion battery is charged with a non-constant current, the average value of the charging current within a preset time period before the battery cell stops charging is obtained as the actual charging current.

[0030] In one technical solution of the above-mentioned lithium ion battery lithium deposition detection method, the step of determining whether lithium deposition occurs in the battery cell comprises:

[0031] Obtaining a voltage difference between the actual terminal voltage and the theoretical terminal voltage;

[0032] Based on the actual charging condition, obtaining a lithium deposition threshold when the relaxation time after charging of the battery cell is terminated reaches the actual relaxation time in the case of lithium deposition, wherein the lithium deposition threshold is threshold information of the voltage difference;

[0033] Whether lithium deposition occurs is determined based on a comparison result between the voltage difference and the lithium deposition threshold.

[0034] In a technical solution of the lithium deposition detection method of the above-mentioned lithium ion battery, obtaining the lithium deposition threshold comprises: respectively obtaining the lithium deposition threshold when the relaxation time after the battery cell charging is terminated reaches the actual relaxation time in the case of each preset degree of lithium deposition;

[0035] The determining whether lithium deposition occurs includes: determining whether lithium deposition occurs to a corresponding degree according to a comparison result of the voltage difference with a lithium deposition threshold value when each preset degree of lithium deposition occurs.

[0036] In a technical solution of the above-mentioned lithium deposition detection method for a lithium ion battery, the actual charging condition includes an actual charging temperature and an actual charging current, and obtaining the lithium deposition threshold further includes:

[0037] Obtaining third calibration data between a preset charging temperature, a charging current, a relaxation time and a lithium deposition threshold;

[0038] The lithium plating threshold is obtained based on the third calibration data and according to the actual charging temperature, the actual charging current and the actual relaxation time.

[0039] In a technical solution of the above-mentioned lithium ion battery lithium deposition detection method, the third calibration data is obtained by the following method:

[0040] Obtaining a first voltage curve of a first relaxation voltage in a relaxation process after charging of a lithium-ion battery is terminated without lithium deposition and at different preset charging temperatures and different preset charging currents;

[0041] Obtaining a second voltage curve of a second relaxation voltage in a relaxation process after charging of the lithium-ion battery is terminated when lithium deposition occurs and at different preset charging temperatures and different preset charging currents;

[0042] Based on the first voltage curve and the second voltage curve, respectively obtaining a relaxation voltage difference between the first relaxation voltage and the second relaxation voltage at different preset relaxation times as a lithium deposition threshold;

[0043] The third calibration data is acquired according to the preset charging temperature, the preset charging current, the preset relaxation time and the lithium plating threshold.

[0044] In a technical solution of the above-mentioned lithium ion battery lithium deposition detection method, the lithium deposition threshold in the third calibration data includes the lithium deposition threshold when the relaxation time after the battery cell charging is terminated reaches the actual relaxation time when each preset degree of lithium deposition occurs.

[0045] In one technical solution of the above-mentioned lithium ion battery lithium deposition detection method, the step of determining whether lithium deposition occurs in the battery cell further comprises:

[0046] After determining that lithium deposition occurs according to the actual terminal voltage and the theoretical terminal voltage in a current judgment cycle, obtaining judgment results of a plurality of previous continuous historical judgment cycles;

[0047] If at least a preset number of judgment results in the judgment results of multiple consecutive historical judgment cycles indicate that lithium deposition has occurred, it is determined that lithium deposition has occurred in the battery cell; otherwise, it is determined that lithium deposition has not occurred in the battery cell;

[0048] And / or, the determining whether lithium deposition occurs in the battery cell further includes: after determining that lithium deposition occurs in the battery cell, outputting alarm information.

[0049] In a second aspect, a computer device is provided, which includes a processor and a storage device, wherein the storage device is suitable for storing multiple program codes, and the program codes are suitable for being loaded and run by the processor to execute the method described in any one of the technical solutions of the above-mentioned lithium ion battery lithium plating detection method.

[0050] In a third aspect, a computer-readable storage medium is provided, wherein a plurality of program codes are stored in the computer-readable storage medium, wherein the program codes are suitable for being loaded and run by a processor to execute the method described in any one of the technical solutions of the above-mentioned lithium plating detection method for lithium-ion batteries.

[0051] In a fourth aspect, a vehicle is provided, comprising a power battery and a computer device as described in the technical solution of the above-mentioned computer device.

[0052] Solution 1. A method for detecting lithium deposition in a lithium-ion battery, characterized in that the method comprises:

[0053] Obtaining the actual terminal voltage of each cell in the lithium-ion battery after charging is terminated and the actual relaxation time when the actual terminal voltage is obtained;

[0054] Obtaining the actual health status and actual charging condition of the lithium-ion battery;

[0055] Based on the actual health state and the actual charging condition, obtaining a theoretical terminal voltage when the relaxation time after charging of each battery cell is terminated reaches the actual relaxation time without lithium plating;

[0056] Whether lithium deposition occurs in the battery cell is determined according to the actual terminal voltage and the theoretical terminal voltage.

[0057] Solution 2. The method according to Solution 1 is characterized in that obtaining the theoretical terminal voltage comprises:

[0058] Based on the actual health state and the actual charging condition, obtaining a theoretical open circuit voltage and theoretical characteristic parameters of the battery cell after charging is terminated without lithium plating;

[0059] Based on the RC equivalent circuit model of the battery cell and according to the theoretical open circuit voltage, the theoretical characteristic parameter and the actual relaxation time, obtaining the theoretical terminal voltage of the battery cell;

[0060] Wherein, the theoretical characteristic parameters include ohmic internal resistance, polarization internal resistance and polarization capacitance.

[0061] Solution 3. The method according to Solution 2, characterized in that the actual charging condition includes an actual charging temperature, and obtaining the theoretical open circuit voltage includes:

[0062] Acquire first calibration data between a preset health state, a charging temperature, and an open circuit voltage;

[0063] The theoretical open circuit voltage is obtained based on the first calibration data and according to the actual health state and the actual charging temperature.

[0064] Solution 4. The method according to Solution 3 is characterized in that the first calibration data is obtained by:

[0065] Obtain the actual open circuit voltage of the battery cell when the lithium-ion battery is fully charged under different preset health states and different preset charging temperatures;

[0066] The first calibration data is acquired according to the preset health state, the preset charging temperature and the actual open circuit voltage.

[0067] Solution 5. The method according to Solution 2 is characterized in that the actual charging condition includes an actual charging temperature and an actual charging current, and obtaining the theoretical characteristic parameter includes:

[0068] Acquire second calibration data between preset health status, charging temperature, charging current and characteristic parameters;

[0069] The theoretical characteristic parameter is obtained based on the second calibration data and in accordance with the actual health state, the actual charging temperature and the actual charging current.

[0070] Solution 6. The method according to Solution 5 is characterized in that the second calibration data is obtained by:

[0071] Respectively obtain the relaxation voltage of the lithium-ion battery after charging is cut off under different preset health states, different preset charging temperatures and different preset charging currents;

[0072] Based on the RC equivalent circuit model of the battery cell and according to the relaxation voltage, obtaining actual characteristic parameters of the battery cell;

[0073] The second calibration data is acquired according to the preset health state, the preset charging current, the preset charging temperature and the actual characteristic parameter.

[0074] Solution 7. The method according to Solution 5, characterized in that obtaining the actual charging current comprises:

[0075] If the lithium-ion battery is charged with a non-constant current, the average value of the charging current within a preset time period before the battery cell stops charging is obtained as the actual charging current.

[0076] Solution 8. The method according to any one of solutions 1 to 7, characterized in that determining whether lithium deposition occurs in the battery cell comprises:

[0077] Obtaining a voltage difference between the actual terminal voltage and the theoretical terminal voltage;

[0078] Based on the actual charging condition, obtaining a lithium deposition threshold when the relaxation time after charging of the battery cell is terminated reaches the actual relaxation time in the case of lithium deposition, wherein the lithium deposition threshold is threshold information of the voltage difference;

[0079] Whether lithium deposition occurs is determined based on a comparison result between the voltage difference and the lithium deposition threshold.

[0080] Solution 9. The method according to Solution 8, characterized in that:

[0081] Obtaining the lithium deposition threshold comprises: respectively obtaining the lithium deposition threshold when the relaxation time after the battery cell charging is terminated reaches the actual relaxation time in the case of each preset degree of lithium deposition;

[0082] The determining whether lithium deposition occurs includes: determining whether lithium deposition occurs to a corresponding degree according to a comparison result of the voltage difference with a lithium deposition threshold value when each preset degree of lithium deposition occurs.

[0083] Solution 10. The method according to Solution 8 is characterized in that the actual charging condition includes an actual charging temperature and an actual charging current, and obtaining the lithium precipitation threshold further includes:

[0084] Obtaining third calibration data between a preset charging temperature, a charging current, a relaxation time and a lithium deposition threshold;

[0085] The lithium plating threshold is obtained based on the third calibration data and according to the actual charging temperature, the actual charging current and the actual relaxation time.

[0086] Solution 11. The method according to Solution 10 is characterized in that the third calibration data is obtained by:

[0087] Obtaining a first voltage curve of a first relaxation voltage in a relaxation process after charging of a lithium-ion battery is terminated without lithium deposition and at different preset charging temperatures and different preset charging currents;

[0088] Obtaining a second voltage curve of a second relaxation voltage in a relaxation process after charging of the lithium-ion battery is terminated when lithium deposition occurs and at different preset charging temperatures and different preset charging currents;

[0089] Based on the first voltage curve and the second voltage curve, respectively obtaining a relaxation voltage difference between the first relaxation voltage and the second relaxation voltage at different preset relaxation times as a lithium deposition threshold;

[0090] The third calibration data is acquired according to the preset charging temperature, the preset charging current, the preset relaxation time and the lithium plating threshold.

[0091] Scheme 12. The method according to Scheme 10 is characterized in that the lithium plating threshold in the third calibration data includes the lithium plating threshold when the relaxation time after the battery cell charging is terminated reaches the actual relaxation time when each preset degree of lithium plating occurs.

[0092] Scheme 13. The method according to Scheme 1, characterized in that:

[0093] The determining whether lithium deposition occurs in the battery cell further includes:

[0094] After determining that lithium deposition occurs according to the actual terminal voltage and the theoretical terminal voltage in a current judgment cycle, obtaining judgment results of a plurality of previous continuous historical judgment cycles;

[0095] If at least a preset number of judgment results in the judgment results of multiple consecutive historical judgment cycles indicate that lithium deposition has occurred, it is determined that lithium deposition has occurred in the battery cell; otherwise, it is determined that lithium deposition has not occurred in the battery cell;

[0096] and / or,

[0097] The determining whether lithium deposition occurs in the battery cell further includes: after determining that lithium deposition occurs in the battery cell, outputting alarm information.

[0098] Scheme 14. A computer device comprising a processor and a storage device, wherein the storage device is suitable for storing multiple program codes, and is characterized in that the program codes are suitable for being loaded and run by the processor to execute the lithium plating detection method for lithium-ion batteries described in any one of Schemes 1 to 13.

[0099] Solution 15. A computer-readable storage medium storing a plurality of program codes, characterized in that the program codes are suitable for being loaded and run by a processor to execute the lithium plating detection method for a lithium-ion battery described in any one of Solutions 1 to 13.

[0100] Solution 16. A vehicle, characterized in that the vehicle includes a power battery and the computer device described in Solution 14.

[0101] The above one or more technical solutions of the present invention have at least one or more of the following beneficial effects:

[0102] In the technical solution of the lithium ion battery lithium deposition detection method provided by the present invention, the actual terminal voltage and theoretical terminal voltage of the lithium ion battery cell at the same relaxation time can be obtained, wherein the theoretical terminal voltage is based on the actual health state and actual charging conditions of the lithium ion battery, and is obtained when lithium deposition does not occur, and it can indicate the state of the battery cell when lithium deposition does not occur. By comparing the actual terminal voltage with the theoretical terminal voltage, it is possible to determine whether lithium deposition occurs in each battery cell in the lithium ion battery. Through the above method, whether it is a mild degree of lithium deposition or a severe degree of lithium deposition, it is possible to accurately determine whether lithium deposition occurs; at the same time, the above method does not require structural modification of the lithium ion battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0103] The disclosure of the present invention will become more easily understood with reference to the accompanying drawings. It is easy for those skilled in the art to understand that these drawings are only for illustrative purposes and are not intended to limit the scope of protection of the present invention. Among them:

[0104] Figure 1 This is a schematic flow chart of the main steps of a lithium deposition detection method for a lithium ion battery according to an embodiment of the present invention;

[0105] Figure 2 is a schematic flow chart of main steps of a method for obtaining a theoretical terminal voltage value according to an embodiment of the present invention;

[0106] Figure 3 It is a schematic diagram of the first-order RC equivalent circuit model;

[0107] Figure 4 It is a schematic diagram of the second-order RC equivalent circuit model;

[0108] Figure 5 1 is a flow chart of main steps of a method for judging whether lithium deposition occurs by comparing actual terminal voltage with theoretical terminal voltage according to an embodiment of the present invention;

[0109] Figure 6 This is a flow chart of main steps of a method for determining whether lithium deposition occurs by using a historical determination cycle according to an embodiment of the present invention;

[0110] Figure 7 is a schematic diagram of RC link voltage when lithium deposition occurs and when lithium deposition does not occur in a battery cell according to an embodiment of the present invention;

[0111] Figure 8 It is a main structural diagram of a computer device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0112] Some embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the protection scope of the present invention.

[0113] In the description of the present invention, "processor" may include hardware, software or a combination of the two. The processor may be a central processing unit, a microprocessor, an image processor, a digital signal processor or any other suitable processor. The processor has data and / or signal processing functions. The processor may be implemented in software, hardware or a combination of the two. Computer-readable storage media include any suitable medium that can store program codes, such as a magnetic disk, a hard disk, an optical disk, a flash memory, a read-only memory, a random access memory, etc. The term "A and / or B" means all possible combinations of A and B, such as only A, only B or A and B.

[0114] The relevant user personal information that may be involved in the various embodiments of this application is strictly in accordance with the requirements of laws and regulations, following the principles of legality, legitimacy and necessity, based on the reasonable purposes of business scenarios, to process the personal information that users actively provide during the use of products / services or generated due to the use of products / services, as well as the personal information obtained with the user's authorization.

[0115] The user personal information processed by the applicant will vary depending on the specific product / service scenario, and shall be based on the specific scenario in which the user uses the product / service, which may involve the user's account information, device information, driving information, vehicle information or other related information. The applicant will treat the user's personal information and its processing with a high degree of diligence.

[0116] The Applicant attaches great importance to the security of user personal information and has adopted reasonable and feasible security protection measures that comply with industry standards to protect user information and prevent personal information from being accessed, disclosed, used, modified, damaged or lost without authorization.

[0117] An embodiment of a method for detecting lithium deposition in a lithium-ion battery is described below.

[0118] See attached Figure 1 , Figure 1 FIG. 1 is a schematic flow chart of the main steps of a lithium deposition detection method for a lithium ion battery according to an embodiment of the present invention. Figure 1 As shown, the lithium plating detection method of a lithium-ion battery in the embodiment of the present invention mainly includes the following steps S101 to S104.

[0119] Step S101: obtaining the actual terminal voltage of each cell in the lithium-ion battery after charging is terminated and the actual relaxation time when the actual terminal voltage is obtained.

[0120] The voltage of a lithium-ion battery will gradually return to a balanced state after charging is terminated. The process from charging termination to recovery to a balanced state is called a relaxation process, and the actual relaxation time is a certain time during the relaxation process.

[0121] Step S102: Acquire the actual health status and actual charging condition of the lithium-ion battery.

[0122] The state of health (SOH) is information describing the health life or aging status of a lithium-ion battery. When the health status is 100%, it indicates that the health life of the lithium-ion battery is the best. The charging conditions are information such as the charging current and charging temperature used when charging a lithium-ion battery.

[0123] Step S103: Based on the actual health status and the actual charging conditions, obtain the theoretical terminal voltage when the relaxation time after charging of each battery cell reaches the actual relaxation time without lithium plating, wherein the actual relaxation time is the actual relaxation time obtained in step S101.

[0124] The theoretical terminal voltage is obtained when the lithium-ion battery is charged under the same charging conditions and in the same health state without lithium deposition, and then the terminal voltage at the same time as the actual relaxation time obtained in step S101 is obtained during the relaxation process after charging is terminated.

[0125] For example, the actual health status of the lithium-ion battery is 80%, the actual charging conditions include the actual charging temperature and the temperature is 25°C, and the actual terminal voltage U is obtained. 实际 The actual relaxation time is 10 seconds after the charging is cut off. Therefore, the theoretical terminal voltage U can be determined 理论 It is the terminal voltage at 10 seconds after charging a lithium-ion battery with a health status of 80% at 25°C and charging is cut off. No lithium deposition occurs in the lithium-ion battery during this process.

[0126] Step S104: Determine whether lithium deposition occurs in the battery cell based on the actual terminal voltage and the theoretical terminal voltage. Since the theoretical terminal voltage is obtained when lithium deposition does not occur in the lithium-ion battery, it can indicate the terminal voltage state when lithium deposition does not occur in the battery cell. If the actual terminal voltage is the same as or close to the theoretical terminal voltage, it indicates that lithium deposition does not occur in the battery cell; if the actual terminal voltage differs greatly from the theoretical terminal voltage, it indicates that lithium deposition occurs in the battery cell. In addition, the degree of difference between the actual terminal voltage and the theoretical terminal voltage can also indicate the degree of lithium deposition; if the degree of difference is relatively large, the degree of lithium deposition is relatively large, otherwise the degree of lithium deposition is relatively low. Therefore, based on the degree of difference between the actual terminal voltage and the theoretical terminal voltage, the degree of lithium deposition can also be accurately analyzed.

[0127] After determining that lithium deposition has occurred, an alarm message can be output to remind the user to promptly inspect the lithium-ion battery. For example, for the power battery on a vehicle, after detecting that lithium deposition has occurred, an alarm message can be sent to the vehicle manufacturer so that the manufacturer can recall the power battery or perform on-site maintenance to ensure vehicle safety.

[0128] Based on the method described in steps S101 to S104, it is possible to accurately analyze whether lithium deposition occurs in the lithium-ion battery, and even the degree of lithium deposition, using the theoretical terminal voltage obtained when no lithium deposition occurs in the lithium-ion battery. At the same time, based on the above method, only the terminal voltage, relaxation time, health status, charging conditions and other information of the lithium-ion battery need to be detected, without modifying the structure of the lithium-ion battery, thereby realizing non-destructive and high-precision lithium deposition detection of the lithium-ion battery.

[0129] The above step S103 and step S104 are described below respectively.

[0130] 1. Explain the above step S103.

[0131] In some implementations of the above step S103, an RC equivalent circuit model of the battery cell may be constructed, and the RC equivalent circuit model may be used to generate the battery cell. Figure 2 The following steps S1031 to S1032 are shown to obtain the theoretical terminal voltage.

[0132] Step S1031: Based on the actual health status and the actual charging conditions, obtain the theoretical open circuit voltage and theoretical characteristic parameters of the battery cell after charging is terminated without lithium plating.

[0133] The theoretical open circuit voltage and theoretical characteristic parameters are obtained by charging lithium-ion batteries in the same health state under the same charging conditions without lithium plating. The theoretical characteristic parameters may include ohmic internal resistance, polarization internal resistance and polarization capacitance.

[0134] See attached Figure 3 and attached Figure 4 , Figure 3 The first-order RC equivalent circuit model is shown as an example. Figure 4 A second-order RC equivalent circuit model is exemplarily shown. Figure 3 OCV in it represents the open circuit voltage of the lithium-ion battery, R0 represents the ohmic internal resistance, R1 represents the polarization internal resistance, C1 represents the polarization capacitance, and U(t) represents the terminal voltage of the lithium-ion battery. Figure 4 R2 also represents the polarization internal resistance, C2 also represents the polarization capacitance, and other parameters are similar to Figure 3 similar.

[0135] It should be noted that those skilled in the art can flexibly set the order of the RC equivalent circuit model according to actual needs, and the embodiments of the present invention do not specifically limit it. In some preferred implementations, a second-order RC equivalent circuit model is used.

[0136] Step S1032: based on the RC equivalent circuit model of the battery cell and according to the theoretical open circuit voltage, theoretical characteristic parameters and actual relaxation time, the theoretical terminal voltage of the battery cell is obtained.

[0137] The calculation formula of the terminal voltage is shown in the following formula (1).

[0138]

[0139] The meanings of the parameters in formula (1) are:

[0140] n represents the order of the RC equivalent circuit model.

[0141] I is the charging current before charging is cut off. If the lithium-ion battery adopts non-constant current charging, the average value of the charging current within the preset time before the battery cell is cut off from charging is obtained as the charging current. Those skilled in the art can flexibly set the specific value of the preset time according to actual needs, and the embodiment of the present invention is not specifically limited. For example, the time length for performing 10 current samplings can be used.

[0142] Ui represents the voltage of the i-th RC link, R i and C i They represent the polarization internal resistance and polarization capacitance in the i-th RC link, respectively. When the lithium-ion battery is fully charged or nearly fully charged and lithium deposition is detected, Ui≈I*R i .

[0143] t is the time after charging is cut off. The actual relaxation time is substituted into time t when calculating the theoretical terminal voltage.

[0144] Based on formula (1), the calculation formulas for the terminal voltage of the first-order and second-order RC equivalent circuit models can be obtained as shown in the following formulas (2) and (3), respectively.

[0145]

[0146]

[0147] Based on the above steps S1031 to S1032, the theoretical terminal voltage of the lithium-ion battery can be obtained conveniently and accurately using the RC equivalent circuit model.

[0148] The method for obtaining the theoretical open circuit voltage and the theoretical characteristic parameters in the above step S1031 is further described below.

[0149] 1. Method for obtaining theoretical open circuit voltage

[0150] In some implementations of the above step S1031, the actual charging condition of the lithium-ion battery may include the actual charging temperature. In this case, the theoretical open circuit voltage may be obtained by performing the following steps 11 to 12.

[0151] Step 11: Obtaining the first calibration data between the preset health status, charging temperature and open circuit voltage. The first calibration data records the corresponding relationship between different health status, different charging temperature and different open circuit voltage, and the corresponding relationship can be recorded in a table.

[0152] In this embodiment, the first calibration data can be pre-constructed, and when the theoretical open circuit voltage needs to be obtained, the first calibration data can be directly called. In this embodiment, the first calibration data can be constructed or obtained through the following steps 111 to 112.

[0153] Step 111: Obtaining the actual open circuit voltage of the battery cell when the lithium-ion battery is fully charged at different preset health states and different preset charging temperatures.

[0154] The preset health status includes but is not limited to 100%, 95%, 90%, 85%, 80%, and the preset charging temperature includes but is not limited to -20℃, 0℃, 15℃, 25℃, 35℃.

[0155] Taking the 100% healthy state as an example, the lithium-ion battery with a 100% healthy state is charged at -20℃, 0℃, 15℃, 25℃, and 35℃ respectively, and the actual open circuit voltage OCV of the battery cell when fully charged is obtained. -20℃ 、OCV 0℃ 、OCV 15℃ 、OCV 25℃ 、OCV 35℃ Based on these data, the charging temperature of -20℃, 0℃, 15℃, 25℃, and 35℃ respectively correlates with the actual open circuit voltage OCV when the health status is 100%. -20℃ 、OCV 0℃ 、OCV 15℃ 、OCV 25℃ 、OCV 35℃ The corresponding relationship.

[0156] Step 112: Obtain first calibration data according to a preset health state, a preset charging temperature, and an actual open circuit voltage.

[0157] A correspondence is established between each preset charging temperature and each actual open circuit voltage under different health states, and the first calibration data can be formed based on these correspondences.

[0158] Based on the method described in step 111 to step 112, the first calibration data reflecting the corresponding relationship between different health states, different charging temperatures and different open circuit voltages can be accurately obtained through experiments.

[0159] Step 12: Based on the first calibration data and according to the actual health state and the actual charging temperature, obtain the theoretical open circuit voltage.

[0160] An open circuit voltage corresponding to both the actual health state and the actual charging temperature is queried from the first calibration data as a theoretical open circuit voltage.

[0161] Based on the method described in step 11 to step 12 above, the theoretical open circuit voltage of the lithium-ion battery can be quickly obtained using the first calibration data.

[0162] 2. Method for obtaining theoretical characteristic parameters

[0163] In some implementations of the above step S1031, the actual charging conditions of the lithium-ion battery may include an actual charging temperature and an actual charging current. In this case, the theoretical characteristic parameters may be obtained through the following steps 21 to 22.

[0164] Step 21: Obtain the second calibration data between the preset health state, charging temperature, charging current and characteristic parameters. The second calibration data records the corresponding relationship between different health states, different charging temperatures, different charging currents and different characteristic parameters, and the corresponding relationship can be recorded in a table.

[0165] In this embodiment, the second calibration data can be pre-constructed, and when the theoretical characteristic parameters need to be obtained, the second calibration data can be directly called. In this embodiment, the second calibration data can be constructed or obtained through the following steps 211 to 213.

[0166] Step 211: respectively obtaining the relaxation voltage of the lithium-ion battery after charging is terminated under different preset health states, different preset charging temperatures, and different preset charging currents. The relaxation voltage may be the relaxation voltage at the end of the relaxation process.

[0167] The preset health status includes but is not limited to 100%, 95%, 90%, 85%, 80%, and the preset charging temperature includes but is not limited to -20℃, 0℃, 15℃, 25℃, 35℃.

[0168] Taking the healthy state of 100% as an example, the lithium-ion battery with a healthy state of 100% is charged at -20℃, 0℃, 15℃, 25℃, and 35℃ respectively, and the relaxation voltage V after charging is cut off is obtained. -20℃ 、V 0℃ 、V 15℃ 、V 25℃ 、V35℃ .

[0169] Step 212: Based on the RC equivalent circuit model of the battery cell and according to the relaxation voltage, actual characteristic parameters of the battery cell are obtained.

[0170] The relaxation voltage is actually also the terminal voltage of the lithium-ion battery. Based on multiple sets of relaxation voltage and charging current data, the actual characteristic parameters can be calculated using the RC equivalent circuit model. It should be noted that the use of the RC equivalent circuit model and the terminal voltage to calculate characteristic parameters such as ohmic internal resistance, polarization internal resistance and polarization capacitance is a conventional method in the field of battery technology, and the embodiment of the present invention does not elaborate on the specific process of calculating the above characteristic parameters.

[0171] Step 213: Obtain second calibration data according to the preset health state, the preset charging current, the preset charging temperature and the actual characteristic parameters.

[0172] A correspondence is established between each preset charging current, each preset charging temperature and each actual characteristic parameter under different health conditions, and the second calibration data can be formed based on these correspondences.

[0173] Based on the method described in steps 211 to 213, the second calibration data reflecting the corresponding relationship between different health states, different charging currents, different charging temperatures and different characteristic parameters can be accurately obtained through experiments.

[0174] Step 22: Based on the second calibration data and in accordance with the actual health state, the actual charging temperature and the actual charging current, obtain theoretical characteristic parameters.

[0175] Characteristic parameters corresponding to the actual health state, the actual charging current and the actual charging temperature are queried from the second calibration data as theoretical characteristic parameters.

[0176] In some cases, the second calibration data may only record a few discrete preset health states and their corresponding data (charging current, charging temperature and characteristic parameters). When querying according to the actual health state, the preset health state with the same value as the actual health state cannot be obtained. In this case, two preset health states adjacent to the actual health state can be obtained, and then the data corresponding to the two preset health states can be interpolated to obtain the charging current, charging temperature and characteristic parameters corresponding to the actual health state. For example, if the actual health state is 92%, the actual health state of 90% and 95% can be obtained and the data of the two can be interpolated.

[0177] Based on the method described in steps 21 to 22 above, the theoretical characteristic parameters of the lithium-ion battery can be quickly obtained using the second calibration data.

[0178] 2. Explain the above step S104.

[0179] In some implementations of the above step S104, Figure 5 The following steps S1041 to S1043 are used to determine whether lithium deposition occurs in the battery cell.

[0180] Step S1041: obtaining a voltage difference between the actual terminal voltage and the theoretical terminal voltage.

[0181] That is: voltage difference ΔU=U 实际 -U 理论 .

[0182] Step S1042: Based on the actual charging condition, a lithium deposition threshold value is obtained when the relaxation time after the cell charging is terminated reaches the actual relaxation time in the case of lithium deposition.

[0183] The lithium deposition threshold is a threshold value obtained by using charging data when the lithium-ion battery is charged under the same charging conditions and in the same health state without lithium deposition. The lithium deposition threshold is the threshold information of the voltage difference, that is, the lithium deposition threshold is the voltage difference threshold.

[0184] Step S1043: Determine whether lithium deposition occurs based on the comparison result between the voltage difference and the lithium deposition threshold. If the voltage difference is less than the lithium deposition threshold, it indicates that the voltage difference is relatively small, and the actual terminal voltage is the same as or relatively close to the theoretical terminal voltage. In this case, lithium deposition does not occur. Otherwise, lithium deposition occurs. In addition, the degree of difference between the voltage difference and the lithium deposition threshold can also indicate the degree of lithium deposition; if the degree of difference is relatively large, the degree of lithium deposition is relatively large, otherwise the degree of lithium deposition is relatively low. Therefore, based on the voltage difference and the lithium deposition threshold, the degree of lithium deposition can also be accurately analyzed.

[0185] Based on the method described in steps S1041 to S1043 above, the voltage difference between the actual terminal voltage and the theoretical terminal voltage can be used to accurately determine whether lithium deposition occurs in the lithium-ion battery and the extent of the deposition.

[0186] The method for obtaining the lithium deposition threshold in the above step S1042 is further described below.

[0187] In some embodiments of the above step S1042, the lithium deposition threshold when the relaxation time after the battery cell charging is terminated reaches the actual relaxation time can also be obtained respectively when each preset degree of lithium deposition occurs, instead of only obtaining one threshold for distinguishing whether lithium deposition occurs.

[0188] In this case, when executing step S1043 to determine whether lithium deposition occurs, it can be determined whether lithium deposition occurs to a corresponding degree based on the comparison result between the voltage difference and the lithium deposition threshold value when each preset degree of lithium deposition occurs.

[0189] In some embodiments, lithium plating thresholds Threshold1, Threshold2, and Threshold3 representing three degrees of mild, moderate, and severe can be obtained. If the voltage difference ΔU < Threshold1, it indicates that no lithium plating has occurred; if Threshold1 ≤ ΔU < Threshold2, it indicates that mild lithium plating has occurred; if Threshold2 ≤ ΔU < Threshold3, it indicates that moderate lithium plating has occurred; if ΔU ≥ Threshold3, it indicates that severe lithium plating has occurred.

[0190] It should be noted that those skilled in the art can flexibly set various different degrees of lithium plating according to actual needs, and the embodiments of the present invention do not make specific limitations.

[0191] In some embodiments of the above step S1042, the actual charging conditions of the lithium-ion battery may include the actual charging temperature and the actual charging current. At this time, the lithium plating threshold can be obtained through the following steps 31 to step 32.

[0192] Step 31: Obtain the third calibration data between the preset charging temperature, charging current, relaxation time, and lithium plating threshold. The third calibration data records the corresponding relationship between different charging temperatures, different charging currents, different relaxation times, and different lithium plating thresholds, and this corresponding relationship can be recorded in the form of a table.

[0193] In this embodiment, the third calibration data can be pre-constructed, and when the lithium plating threshold needs to be obtained, the third calibration data can be directly called. In this embodiment, the third calibration data can be constructed or obtained through the following steps 311 to step 314.

[0194] Step 311: Obtain the first voltage curve of the first relaxation voltage during the relaxation process after the lithium-ion battery is charged to cut-off under different preset charging temperatures and different preset charging currents without lithium plating.

[0195] The preset charging temperatures include but are not limited to -20°C, 0°C, 15°C, 25°C, 35°C, and the preset charging currents include but are not limited to 0.5C, 1C, 1.5C, 2C.

[0196] Taking the charging temperature of -20°C as an example, in the case where no lithium plating occurs in the lithium-ion battery, the lithium-ion battery is charged with a charging current of 0.5C, and then the dynamic change curve of the first relaxation voltage during the relaxation process after charging to cut-off is obtained, that is, the first voltage curve. Similarly, in the case where no lithium plating occurs in the lithium-ion battery, the lithium-ion battery is charged with 1C, 1.5C, and 2C respectively, and the corresponding first voltage curves are obtained.

[0197] Step 312: Obtain a second voltage curve of a second relaxation voltage in the relaxation process after charging of the lithium-ion battery is terminated when lithium plating occurs and at different preset charging temperatures and different preset charging currents. This step is similar to the implementation process of step 311, the only difference being that this step is performed when lithium plating occurs. Further, when it is necessary to obtain the lithium plating threshold when multiple different preset degrees of lithium plating occur, the second voltage curve can be obtained when a preset degree of lithium plating occurs and at different preset charging temperatures and different preset charging currents. Based on this, the lithium plating threshold in the third calibration data can include the lithium plating threshold when the relaxation time after charging of the battery cell is terminated reaches the actual relaxation time when each preset degree of lithium plating occurs.

[0198] Step 313: Based on the first voltage curve and the second voltage curve, respectively obtain relaxation voltage differences between the first relaxation voltage and the second relaxation voltage at different preset relaxation times as lithium deposition thresholds.

[0199] The preset relaxation time includes but is not limited to 1000s, 2000s, 3000s, ..., 1400s, and 15000s. Taking the relaxation time of 1000s as an example, the first relaxation voltage corresponding to 1000s in the first voltage curve is obtained, the second relaxation voltage corresponding to 1000s in the second voltage curve is obtained, and then the voltage difference between the first and second relaxation voltages is obtained, and this voltage difference is used as the lithium precipitation threshold corresponding to the relaxation time of 1000s.

[0200] Step 314: Obtain third calibration data according to the preset charging temperature, the preset charging current, the preset relaxation time and the lithium deposition threshold.

[0201] A corresponding relationship is established between each preset charging temperature, each preset charging current, each preset relaxation time and each lithium precipitation threshold value, and the third calibration data can be formed based on these corresponding relationships.

[0202] Based on the method described in steps 311 to 314, the third calibration data reflecting the corresponding relationship between different charging temperatures, different charging currents, different relaxation times and different lithium precipitation thresholds can be accurately obtained by experiment.

[0203] Step 32: Based on the third calibration data and in accordance with the actual charging temperature, the actual charging current and the actual relaxation time, a lithium deposition threshold is obtained.

[0204] A lithium deposition threshold value corresponding to the actual charging temperature, the actual charging current and the actual relaxation time is queried from the third calibration data as the lithium deposition threshold value to be obtained.

[0205] Based on the method described in steps 31 to 32 above, the lithium plating threshold of the lithium-ion battery can be quickly obtained using the third calibration data.

[0206] In some implementations of the above step S104, Figure 6 The following steps S201 to S204 are shown to determine whether lithium deposition occurs in the battery cell.

[0207] Step S201: after determining that lithium deposition has occurred according to the actual terminal voltage and the theoretical terminal voltage in the current judgment cycle, obtaining judgment results of a plurality of previous continuous historical judgment cycles.

[0208] Step S202: determining that at least a preset number of the judgment results of a plurality of consecutive historical judgment cycles indicate that lithium deposition has occurred;

[0209] If so, it indicates that the possibility of misjudgment is low, and it can be determined that lithium deposition has indeed occurred in the battery cell, so it can be transferred to step S203; if not, it indicates that a misjudgment may have occurred. For example, if a data jump occurs when collecting current, voltage and other data, it may lead to a misjudgment, so it can be transferred to step S204.

[0210] Step S203: Determine whether lithium deposition occurs in the battery cell.

[0211] Step S204: determining that no lithium deposition occurs in the battery cell.

[0212] Based on the method described in steps S201 to S204 above, the judgment result of the historical judgment cycle can be used to correct the judgment result of the current judgment cycle to ensure the accuracy of lithium plating detection.

[0213] The following is combined with Figure 4 and attached Figure 7 , the technical effect of the lithium plating detection method for lithium-ion batteries provided by the present invention is explained.

[0214] like Figure 7 As shown in the figure, if lithium plating does not occur during the charging process of the lithium-ion battery, after the charging is terminated Figure 4 The voltage of the two RC links in the RC equivalent circuit model will decrease according to the preset exponential curve ( Figure 7 (shown by the solid line in FIG), at this time, the theoretical terminal voltage U(t) calculated based on formula (3) is basically the same as the actual terminal voltage.

[0215] If lithium ions are deposited during the charging process of a lithium-ion battery, the metal deposited on the negative electrode of the lithium-ion battery will dissolve and embed into the interlayer of the negative electrode under the induction of concentration difference after the charging is terminated. This process will have the opposite effect of depolarization, causing the voltage of the entire battery to rise. The actual value of the voltage of the RC link ( Figure 7 The dotted line in the figure will deviate Figure 7 The voltage is shown by the solid line.

[0216] However, in practical applications, only when serious lithium deposition occurs can the deviation of the dotted line from the solid line be used to detect whether lithium deposition occurs. If serious lithium deposition does not occur, such as when only slight lithium deposition occurs, the deviation between the dotted line and the solid line is very small, and it is difficult to distinguish with the naked eye, so it is very likely to cause misjudgment. The lithium deposition detection method provided by the present invention can overcome the above problem, and even slight lithium deposition can be accurately detected.

[0217] It should be pointed out that although the various steps in the above embodiments are described in a specific order, those skilled in the art can understand that in order to achieve the effect of the present invention, different steps do not have to be executed in such an order, they can be executed simultaneously (in parallel) or in other orders. These adjusted schemes are equivalent to the technical schemes described in the present invention, and therefore will also fall within the scope of protection of the present invention.

[0218] It is understood by those skilled in the art that the present invention implements all or part of the processes in the method of the above embodiment, and can also be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a computer-readable storage medium, and the computer program can implement the steps of the above-mentioned various method embodiments when executed by the processor. Among them, the computer program includes computer program code, and the computer program code can be in source code form, object code form, executable file or some intermediate form. The computer-readable storage medium may include: any entity or device, medium, U disk, mobile hard disk, disk, optical disk, computer memory, read-only memory, random access memory, electric carrier signal, telecommunication signal and software distribution medium that can carry the computer program code. It should be noted that the content contained in the computer-readable storage medium can be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, computer-readable storage media do not include electric carrier signals and telecommunication signals.

[0219] Furthermore, the present invention also provides a computer device.

[0220] See attached Figure 8 , Figure 8 1 is a schematic diagram of the main structure of a computer device embodiment according to the present invention. Figure 8As shown, the computer device in the embodiment of the present invention mainly includes a storage device and a processor. The storage device can be configured to store a program for executing the lithium deposition detection method of the lithium-ion battery of the above method embodiment, and the processor can be configured to execute the program in the storage device, which includes but is not limited to the program for executing the lithium deposition detection method of the lithium-ion battery of the above method embodiment. For ease of explanation, only the part related to the embodiment of the present invention is shown. For specific technical details not disclosed, please refer to the method part of the embodiment of the present invention.

[0221] In an embodiment of the present invention, the computer device may be a control device device formed by various electronic devices. In some possible implementations, the computer device may include multiple storage devices and multiple processors. The program for executing the lithium deposition detection method of the lithium-ion battery of the above method embodiment can be divided into multiple subprograms, and each subprogram can be loaded and run by the processor to execute different steps of the lithium deposition detection method of the lithium-ion battery of the above method embodiment. Specifically, each subprogram can be stored in different storage devices, and each processor can be configured to execute the program in one or more storage devices to jointly implement the lithium deposition detection method of the lithium-ion battery of the above method embodiment, that is, each processor executes different steps of the lithium deposition detection method of the lithium-ion battery of the above method embodiment to jointly implement the lithium deposition detection method of the lithium-ion battery of the above method embodiment.

[0222] The above-mentioned multiple processors may be processors deployed on the same device. For example, the above-mentioned computer device may be a high-performance device composed of multiple processors, and the above-mentioned multiple processors may be processors configured on the high-performance device. In addition, the above-mentioned multiple processors may also be processors deployed on different devices. For example, the above-mentioned computer device may be a server cluster, and the above-mentioned multiple processors may be processors on different servers in the server cluster.

[0223] Furthermore, the present invention also provides a computer-readable storage medium.

[0224] In an embodiment of a computer-readable storage medium according to the present invention, the computer-readable storage medium may be configured to store a program for executing the lithium deposition detection method of a lithium-ion battery of the above-mentioned method embodiment, and the program may be loaded and run by a processor to implement the above-mentioned lithium deposition detection method of a lithium-ion battery. For ease of explanation, only the parts related to the embodiment of the present invention are shown. For specific technical details not disclosed, please refer to the method part of the embodiment of the present invention. The computer-readable storage medium may be a storage device formed by various electronic devices. Optionally, the computer-readable storage medium in the embodiment of the present invention is a non-temporary computer-readable storage medium.

[0225] Furthermore, the present invention also provides a vehicle.

[0226] In an embodiment of a vehicle according to the present invention, the vehicle may include the computer device described in the above-mentioned computer device embodiment. In this embodiment, the vehicle may be an autonomous driving vehicle, an unmanned vehicle, or the like. In addition, according to the type of power source, in this embodiment, the vehicle may be an electric vehicle, a hybrid vehicle that mixes electric energy with fuel, or a hybrid vehicle that mixes electric energy with other energy sources.

[0227] So far, the technical solution of the present invention has been described in conjunction with an embodiment shown in the accompanying drawings, but it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

Claims

1. A lithium ion battery lithium deposition detection method, characterized in that: The method comprises: Obtaining the actual terminal voltage of each cell in the lithium-ion battery after charging is terminated and the actual relaxation time when the actual terminal voltage is obtained; Obtaining the actual health status and actual charging condition of the lithium-ion battery; Based on the actual health state and the actual charging condition, obtaining a theoretical terminal voltage when the relaxation time after charging of each battery cell is terminated reaches the actual relaxation time without lithium plating; Whether lithium deposition occurs in the battery cell is determined according to the actual terminal voltage and the theoretical terminal voltage.

2. The method according to claim 1, characterized in that Obtaining the theoretical terminal voltage includes: Based on the actual health state and the actual charging condition, obtaining a theoretical open circuit voltage and theoretical characteristic parameters of the battery cell after charging is terminated without lithium plating; Based on the RC equivalent circuit model of the battery cell and according to the theoretical open circuit voltage, the theoretical characteristic parameter and the actual relaxation time, obtaining the theoretical terminal voltage of the battery cell; Wherein, the theoretical characteristic parameters include ohmic internal resistance, polarization internal resistance and polarization capacitance.

3. The method according to claim 2, characterized in that The actual charging condition includes an actual charging temperature, and obtaining the theoretical open circuit voltage includes: Acquire first calibration data between a preset health state, a charging temperature, and an open circuit voltage; The theoretical open circuit voltage is obtained based on the first calibration data and according to the actual health state and the actual charging temperature.

4. The method according to claim 3, characterized in that The first calibration data is obtained by: Obtain the actual open circuit voltage of the battery cell when the lithium-ion battery is fully charged under different preset health states and different preset charging temperatures; The first calibration data is acquired according to the preset health state, the preset charging temperature and the actual open circuit voltage.

5. The method according to claim 2, characterized in that: The actual charging condition includes an actual charging temperature and an actual charging current, and obtaining the theoretical characteristic parameter includes: Acquire second calibration data between preset health status, charging temperature, charging current and characteristic parameters; The theoretical characteristic parameter is obtained based on the second calibration data and in accordance with the actual health state, the actual charging temperature and the actual charging current.

6. The method according to claim 5, characterized in that The second calibration data is obtained by: Respectively obtain the relaxation voltage of the lithium-ion battery after charging is cut off under different preset health states, different preset charging temperatures and different preset charging currents; Based on the RC equivalent circuit model of the battery cell and according to the relaxation voltage, obtaining actual characteristic parameters of the battery cell; The second calibration data is acquired according to the preset health state, the preset charging current, the preset charging temperature and the actual characteristic parameter.

7. The method according to claim 5, characterized in that Obtaining the actual charging current includes: If the lithium-ion battery is charged with a non-constant current, the average value of the charging current within a preset time period before the battery cell stops charging is obtained as the actual charging current.

8. The method according to any one of claims 1 to 7, characterized in that The determining whether lithium deposition occurs in the battery cell comprises: Obtaining a voltage difference between the actual terminal voltage and the theoretical terminal voltage; Based on the actual charging condition, obtaining a lithium deposition threshold when the relaxation time after charging of the battery cell is terminated reaches the actual relaxation time in the case of lithium deposition, wherein the lithium deposition threshold is threshold information of the voltage difference; Whether lithium deposition occurs is determined based on a comparison result between the voltage difference and the lithium deposition threshold.

9. The method according to claim 8, characterized in that Obtaining the lithium deposition threshold comprises: respectively obtaining the lithium deposition threshold when the relaxation time after the battery cell charging is terminated reaches the actual relaxation time in the case of each preset degree of lithium deposition; The determining whether lithium deposition occurs includes: determining whether lithium deposition occurs to a corresponding degree according to a comparison result of the voltage difference with a lithium deposition threshold value when each preset degree of lithium deposition occurs.

10. The method according to claim 8, characterized in that The actual charging condition includes an actual charging temperature and an actual charging current, and obtaining the lithium deposition threshold further includes: Obtaining third calibration data between a preset charging temperature, a charging current, a relaxation time and a lithium deposition threshold; The lithium plating threshold is obtained based on the third calibration data and according to the actual charging temperature, the actual charging current and the actual relaxation time.

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