Method and device for determining DC internal resistance of single cell, and electronic equipment

Abstract

The invention provides a method and device for determining the direct current internal resistance of a single cell and electronic equipment, and relates to the technical field of circuits, and the method comprises the steps: carrying out the pre-charging processing of a to-be-tested single cell, and enabling the to-be-tested single cell to be in a preset stable state; according to a preset discharge duration, discharging the to-be-tested single cell to obtain discharge process data within the preset discharge duration; according to the discharge process data, obtaining a first cell temperature of the to-be-tested single cell at a preset discharge end time within a preset discharge duration and an initial DC internal resistance of the to-be-tested single cell at the preset discharge end time; and according to the first cell temperature, adopting a preset temperature correction coefficient of the same batch of single cells to correct the initial DC internal resistance, and obtaining a target DC internal resistance of the to-be-measured single cell. According to the invention, the precision of the direct-current internal resistance test and the stability of the direct-current internal resistance test result can be improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of circuit, in particular to a method and device for determining direct current resistance of single battery cell and electronic equipment. BACKGROUND

[0002] In the production process of lithium ion battery, the direct current resistance of single battery cell is an important parameter for measuring its electrochemical performance and consistency. In order to ensure that the battery cells have good consistency and reliability, the direct current resistance of the battery cells needs to be tested quickly and accurately online after the formation and capacity test of the battery cells are completed.

[0003] In the prior art, the direct current resistance of single battery cell is tested by first pre-treating the battery cell according to the requirements, making the battery cell in a stable state through specific treatment after the battery formation, and applying constant current discharge to the lithium ion battery under a specific state of charge by using constant current discharge combined with voltage sampling during the test.

[0004] However, the state of charge of the battery cell before the test is not effectively unified in the prior art, resulting in measurement deviation of the direct current resistance of different battery cells due to the difference in state of charge, and it is difficult to ensure the consistency of the test data under the condition of temperature fluctuation in the production line environment, and high-precision and stable direct current resistance test cannot be realized. SUMMARY

[0005] The present application aims to solve the above problems in the prior art, and provides a method and device for determining direct current resistance of single battery cell and electronic equipment, so as to improve the precision of direct current resistance test and the stability of direct current resistance test results.

[0006] To achieve the above purpose, the technical solutions adopted by the embodiments of the present application are as follows:

[0007] In a first aspect, an embodiment of the present application provides a method for determining direct current resistance of single battery cell, which comprises:

[0008] Pre-charging the single battery cell to be tested to make the single battery cell to be tested in a preset stable state;

[0009] Discharging the single battery cell to be tested according to a preset discharge time to obtain discharge process data within the preset discharge time;

[0010] According to the discharge process data, obtaining a first battery cell temperature of the single battery cell to be tested at a preset discharge end time within the preset discharge time, and an initial direct current resistance of the single battery cell to be tested at the preset discharge end time;

[0011] According to the first cell temperature, a preset temperature correction coefficient of the same batch of single cells is adopted to correct the initial direct current resistance, so as to obtain a target direct current resistance of the single cell to be tested.

[0012] Optionally, the pre-charging treatment of the single cell to be tested is such that the single cell to be tested is in a preset stable state, and the method comprises:

[0013] According to the first current density, the single cell to be tested is pre-charged in a constant current charging mode.

[0014] When the charging voltage of the single cell to be tested reaches a first preset voltage, the single cell to be tested is continuously charged in a preset constant voltage charging mode until the charging current of the single cell to be tested is less than a preset minimum charging current.

[0015] Optionally, before the single cell to be tested is discharged according to the preset discharge duration to obtain the discharge process data within the preset discharge duration, the method further comprises:

[0016] The charged single cell to be tested is subjected to a standing treatment to obtain self-discharge process data of the single cell to be tested.

[0017] According to the self-discharge process data, it is determined whether the single cell to be tested meets a preset direct current resistance test condition.

[0018] The single cell to be tested is discharged according to the preset discharge duration to obtain the discharge process data within the preset discharge duration, and the method comprises:

[0019] If the single cell to be tested meets the preset direct current resistance test condition, the single cell to be tested is discharged according to the preset discharge duration to obtain the discharge process data within the preset discharge duration.

[0020] Optionally, the standing treatment of the charged single cell to be tested to obtain the self-discharge process data of the single cell to be tested comprises:

[0021] The charged single cell to be tested is left to stand for a first preset duration, and a first open-circuit voltage at the end of the standing is recorded.

[0022] After the first preset duration ends, the single cell to be tested is left to stand for a second preset duration, and a plurality of second open-circuit voltages within the second preset duration are recorded; the self-discharge process data comprises the first open-circuit voltage and the plurality of second open-circuit voltages.

[0023] Optionally, the determining whether the to-be-tested single battery satisfies the preset DC resistance test condition according to the self-discharge process data comprises:

[0024] According to the self-discharge process data, a self-discharge curve of the to-be-tested single battery is obtained;

[0025] According to the self-discharge curve, a self-discharge rate of the to-be-tested single battery is determined;

[0026] It is determined whether the self-discharge rate is less than or equal to a preset self-discharge rate threshold value;

[0027] If the self-discharge rate is less than or equal to the preset self-discharge rate threshold value, it is determined that the to-be-tested single battery satisfies the preset DC resistance test condition;

[0028] If the self-discharge rate is greater than the preset self-discharge rate threshold value, it is determined that the to-be-tested single battery does not satisfy the preset DC resistance test condition.

[0029] Optionally, the discharging the to-be-tested single battery according to the preset discharge duration to obtain discharge process data in the preset discharge duration comprises:

[0030] According to the second current density and the preset discharge duration, a preset constant-current discharge mode is adopted to discharge the to-be-tested single battery, and discharge process data in the preset discharge duration is obtained.

[0031] Optionally, the discharge process data in the preset discharge duration comprises a plurality of third open-circuit voltages in the preset discharge duration and the first battery temperature;

[0032] The first battery temperature of the to-be-tested single battery at a preset discharge end time in the preset discharge duration and an initial DC resistance of the to-be-tested single battery are obtained according to the discharge process data, and the method comprises:

[0033] According to the plurality of third open-circuit voltages, a discharge curve of the preset discharge duration is obtained;

[0034] According to the discharge curve, the initial DC resistance is calculated.

[0035] Optionally, before the initial DC resistance is corrected according to the preset temperature correction coefficient of the single battery in the same batch to obtain a target DC resistance of the to-be-tested single battery, the method further comprises:

[0036] A plurality of single batteries in the same batch are placed in an oven to obtain single batteries under a plurality of temperature gradients in a preset temperature range;

[0037] respectively, to obtain the DC internal resistance under the plurality of temperature gradients;

[0038] According to the DC internal resistance under the plurality of temperature gradients, the temperature correction coefficient is obtained.

[0039] In a second aspect, another embodiment of the present application provides a DC internal resistance determination device for a single battery cell, and the device comprises:

[0040] A pre-charging module is configured to perform pre-charging processing on a single battery cell to be tested, so that the single battery cell to be tested is in a preset stable state.

[0041] A discharging module is configured to discharge the single battery cell to be tested according to a preset discharging duration, to obtain discharging process data within the preset discharging duration.

[0042] An obtaining module is configured to obtain a first battery cell temperature of the single battery cell to be tested at a preset discharging end time within the preset discharging duration, and an initial DC internal resistance of the single battery cell to be tested at the preset discharging end time, according to the discharging process data.

[0043] A correction module is configured to correct the initial DC internal resistance according to the first battery cell temperature, by using a preset temperature correction coefficient of a same batch of single battery cells, to obtain a target DC internal resistance of the single battery cell to be tested.

[0044] In a third aspect, another embodiment of the present application provides an electronic device, which comprises a processor, a memory and a bus, the memory stores machine readable instructions executable by the processor, when the electronic device is running, the processor and the memory communicate through the bus, and the processor executes the machine readable instructions to perform the steps of the single battery cell DC internal resistance determination method according to any one of the first aspect.

[0045] In a fourth aspect, another embodiment of the present application provides a storage medium, which stores a computer program, when the computer program is run by a processor, the steps of the single battery cell DC internal resistance determination method according to any one of the first aspect are performed.

[0046] The present application has the following beneficial effects:

[0047] The application provides a method and device for determining the direct current resistance of a single battery cell and an electronic device. The method comprises the following steps: pre-charging the single battery cell to be tested, so that the single battery cell to be tested is in a preset stable state, thereby maintaining the accuracy and consistency of the test data, and improving the safety of the test process and the single battery cell; discharging the single battery cell to be tested for a preset discharging time, so as to obtain discharging process data within the preset discharging time; obtaining a first battery cell temperature of the single battery cell to be tested at a preset discharging end time within the preset discharging time, and an initial direct current resistance of the single battery cell to be tested at the preset discharging end time according to the discharging process data; correcting the initial direct current resistance by using a preset temperature correction coefficient of the single battery cell in the same batch according to the first battery cell temperature, so as to obtain a target direct current resistance of the single battery cell to be tested. The initial direct current resistance is corrected based on the first battery cell temperature, so that the resistance value of the direct current resistance can be corrected under different battery cell temperatures, and the accuracy of the direct current resistance test and the stability of the direct current resistance test result can be improved. BRIEF DESCRIPTION OF DRAWINGS

[0048] In order to more clearly illustrate the technical solutions of the embodiments of the application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the application, and therefore should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor.

[0049] Figure 1 The application provides a method for determining the direct current resistance of a single battery cell.

[0050] Figure 2 The application provides a flowchart for pre-charging the single battery cell in the method for determining the direct current resistance of the single battery cell.

[0051] Figure 3 The application provides a flowchart for determining the discharging process data in the method for determining the direct current resistance of the single battery cell.

[0052] Figure 4 The application provides a flowchart for determining the self-discharging process data in the method for determining the direct current resistance of the single battery cell.

[0053] Figure 5 The application provides a flowchart for determining the self-discharging process data in the method for determining the direct current resistance of the single battery cell.

[0054] Figure 6A flowchart for determining an initial DC resistance in a method for determining a DC resistance of a single battery cell is provided in an embodiment of the present application;

[0055] Figure 7 A flowchart for determining a temperature correction coefficient in a method for determining a DC resistance of a single battery cell is provided in an embodiment of the present application;

[0056] Figure 8 A DC resistance fitting graph of a temperature correction coefficient is provided in an embodiment of the present application;

[0057] Figure 9 A structural diagram of a DC resistance determination device of a single battery cell is provided in an embodiment of the present application;

[0058] Figure 10 A structural diagram of an electronic device is provided in an embodiment of the present application. DETAILED DESCRIPTION

[0059] To make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described below in conjunction with the accompanying drawings in the embodiments of the present application. It should be understood that the accompanying drawings in the present application are only intended to illustrate and describe the present application, and are not intended to limit the scope of protection of the present application. In addition, it should be understood that the accompanying drawings are not drawn to scale. The flowcharts show the operations implemented according to some embodiments of the present application. It should be understood that the operations of the flowcharts can not be implemented in sequence, and the steps without logical context relationship can be reversed in sequence or implemented simultaneously. In addition, one or more other operations can be added to the flowcharts or one or more operations can be removed from the flowcharts under the guidance of the content of the present application.

[0060] In addition, the described embodiments are only some of the embodiments of the present application, not all the embodiments. The components of the embodiments of the present application described and shown in the accompanying drawings can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0061] It should be noted that the term "comprising" will be used in the embodiments of the present application to indicate the presence of the features declared thereafter, but does not exclude the addition of other features.

[0062] To clearly describe the method provided in the embodiments of the present application, the method will be described below in conjunction with multiple accompanying drawings, Figure 1A direct current resistance determination method of a single battery cell is provided for an embodiment of the present application, as shown in the method comprises: Figure 1

[0063] Step 101, pre-charge processing is performed on the single battery cell to be tested, so that the single battery cell to be tested is in a preset stable state.

[0064] The single battery cell to be tested is the smallest energy storage unit, and the pre-charge processing is to pre-charge the single battery cell to be tested before testing, which can be constant voltage charging, constant current charging, or charging in a combination of constant voltage and constant current. The preset stable state can be a voltage stable state, a temperature stable state, a current state stable state, or a state of charge parameter stable state.

[0065] Optionally, the direct current resistance determination method of the single battery cell in the present application is applied to a step after the capacity test of the single battery cell on the production line of the single battery cell. After the capacity test of the single battery cell, the pre-charge processing is performed on the single battery cell to be tested, so that the single battery cell to be tested is in a preset stable state. The direct current resistance determination method of the single battery cell in the present application can also be after other steps on the production line of the single battery cell, which is not limited in the embodiment of the present application.

[0066] Step 102, according to the preset discharge time, the single battery cell to be tested is discharged to obtain discharge process data within the preset discharge time.

[0067] The preset discharge time can be determined according to the properties, capacity or test requirements of the single battery cell. The properties of the single battery cell can be ternary lithium battery cell, lithium iron phosphate battery cell, etc. Different properties of the battery cell correspond to different preset discharge times. Different capacities of the single battery cell correspond to different preset discharge times. Different test requirements correspond to different test times, and the preset discharge time is also different. The preset discharge time can be 0.5-30 seconds.

[0068] The discharge process data within the preset discharge time can include the voltage, state of charge parameter, etc. of the single battery cell corresponding to different times, which is not limited in the embodiment of the present application.

[0069] Optionally, according to the preset discharge time, the single battery cell to be tested is discharged by using the corresponding discharge current to obtain the time, voltage, state of charge parameter, etc. of the discharge process data within the preset discharge time.

[0070] Step 103, according to the discharge process data, the first battery cell temperature of the single battery cell to be tested at the preset discharge end time within the preset discharge time is obtained, and the initial direct current resistance of the single battery cell to be tested at the preset discharge end time is obtained.

[0071] ​The first battery cell temperature can be obtained by arranging a temperature sensing device on the side or center of the battery cell to be tested. The initial DC resistance at the preset discharge end time is determined according to the discharge current and the voltage of the battery cell to be tested.

[0072] Optionally, according to the discharge process data, the first battery cell temperature of the battery cell to be tested at the preset discharge end time within the preset discharge duration and the voltage data are obtained, and the initial DC resistance at the preset discharge end time is determined according to the voltage data and the discharge current.

[0073] In step 104, according to the first battery cell temperature, the initial DC resistance is corrected by using the preset temperature correction coefficient of the battery cells in the same batch to obtain the target DC resistance of the battery cell to be tested.

[0074] The preset temperature correction is determined according to the plurality of initial DC resistances of the battery cells in the same batch at different temperatures, and is used to correct the error of the initial DC resistance of the battery cell to be tested caused by temperature.

[0075] Optionally, since the ambient temperature is not the same during the detection process of the battery cell to be tested, there will be an error caused by temperature, and therefore it is necessary to correct the initial DC resistance of the battery cell according to the preset temperature correction coefficient of the battery cell to obtain the target DC resistance of the battery cell to be tested.

[0076] Optionally, according to the first battery cell temperature T1 and the standard temperature 25℃, the initial DC resistance R0 is corrected according to the temperature correction coefficient C0 to obtain the target DC resistance R of the battery cell to be tested, that is, R=R0+C0×(T1-25).

[0077] In the embodiments of the present application, the battery cell to be tested is pre-charged to make the battery cell to be tested in a preset stable state, so as to maintain the accuracy and consistency of the test data, and at the same time, the battery cell to be tested in the preset stable state can improve the safety of the test process and the battery cell. According to the preset discharge duration, the battery cell to be tested is discharged to obtain the discharge process data within the preset discharge duration; according to the discharge process data, the first battery cell temperature of the battery cell to be tested at the preset discharge end time within the preset discharge duration and the initial DC resistance of the battery cell to be tested at the preset discharge end time are obtained; according to the first battery cell temperature, the initial DC resistance is corrected by using the preset temperature correction coefficient of the battery cells in the same batch to obtain the target DC resistance of the battery cell to be tested. The initial DC resistance is corrected based on the first battery cell temperature, so that the resistance value of the DC resistance can be corrected under different battery cell temperatures, which can significantly improve the accuracy of the DC resistance test and the stability of the DC resistance test result.

[0078] On the basis of the above-mentioned embodiments, the application further provides a process for pre-charging the single battery cell in the direct current resistance determination method of the single battery cell, Figure 2 For the embodiment of the application, a process schematic diagram for pre-charging the single battery cell in the direct current resistance determination method of the single battery cell is shown in Figure 2 As shown in the above step 101, the pre-charging process is performed on the single battery cell to be tested, so that the single battery cell to be tested is in a preset stable state, which includes:

[0079] Step 201, pre-charge the single battery cell to be tested in a constant current charging mode according to the first current density.

[0080] The first current density can be 0.1-0.5 times of the capacity of the single battery cell, that is, the single battery cell is charged at a low rate.

[0081] Optionally, pre-charge the single battery cell to be tested in a constant current charging mode according to the first current density of 0.1-0.5 times of the capacity of the single battery cell.

[0082] Step 202, continue to charge the single battery cell to be tested in a preset constant voltage charging mode when the charging voltage of the single battery cell to be tested reaches the first preset voltage, until the charging current of the single battery cell to be tested is less than the preset minimum charging current.

[0083] The first preset voltage value can be any value between 3 volts and 3.6 volts, which is determined according to the properties of the single battery cell. The preset minimum charging current is any value between 0.01 ampere and 0.05 ampere, which is determined according to the properties of the single battery cell.

[0084] Optionally, according to the first current density, the single battery cell to be tested is charged in a constant current charging mode, and when the charging voltage of the single battery cell to be tested reaches the first preset voltage, the single battery cell to be tested is charged in a preset constant voltage charging mode according to the first preset voltage value, until the charging current of the single battery cell to be tested is less than the preset minimum charging current.

[0085] In the embodiment of the application, the single battery cell to be tested is pre-charged in a constant current charging mode according to the first current density, and when the charging voltage of the single battery cell to be tested reaches the first preset voltage, the single battery cell to be tested is charged in a preset constant voltage charging mode, until the charging current of the single battery cell to be tested is less than the preset minimum charging current. The application realizes fast and efficient charging through constant current charging, and ensures that the single battery cell to be tested is in a preset stable state through constant voltage charging.

[0086] On the basis of the above-mentioned embodiments, the application further provides a process for pre-charging the single battery cell in the direct current resistance determination method of the single battery cell, Figure 3A flowchart for determining discharge process data in a method for determining the direct current resistance of a single battery cell is provided for the embodiments of the present application, as shown in Figure 3 Before the discharge process data within the preset discharge duration is obtained in step 102 above according to the preset discharge duration, the method further includes:

[0087] Step 301: The charged single battery cell to be tested is subjected to a standing treatment, and self-discharge process data of the single battery cell to be tested is obtained.

[0088] The standing time can be 3-5 days, and the specific time is determined according to the properties of the single battery cell and the testing requirements. The self-discharge process data can include discharge time, discharge state of charge, open-circuit voltage, and other discharge-related data, which are not limited by the embodiments of the present application.

[0089] Optionally, the charged single battery cell to be tested is subjected to a standing treatment, and discharge time, discharge state of charge, open-circuit voltage, and other discharge-related parameters and related data during the standing process of the single battery cell to be tested are obtained.

[0090] Step 302: Whether the single battery cell to be tested meets the preset direct current resistance testing condition is determined according to the self-discharge process data.

[0091] The preset direct current resistance testing condition can be a capacity attenuation condition, a cycle life condition, or a safety risk condition.

[0092] Optionally, whether the single battery cell to be tested meets the preset direct current resistance testing condition, that is, whether the single battery cell to be tested meets the capacity attenuation condition, the cycle life condition, or the safety risk condition, is determined according to the self-discharge process data.

[0093] The discharge of the single battery cell to be tested according to the preset discharge duration to obtain the discharge process data within the preset discharge duration in step 102 above includes:

[0094] Step 303: If the single battery cell to be tested meets the preset direct current resistance testing condition, the discharge of the single battery cell to be tested according to the preset discharge duration is performed to obtain the discharge process data within the preset discharge duration.

[0095] Optionally, if the single battery cell to be tested meets the preset direct current resistance testing condition, it indicates that there is no abnormal problem in the testing process of the single battery cell to be tested, and the discharge of the single battery cell to be tested according to the preset discharge duration is performed to obtain the discharge process data within the preset discharge duration.

[0096] In the embodiment of the present application, the charged to-be-tested single battery is subjected to static treatment to obtain self-discharge process data of the to-be-tested single battery; whether the to-be-tested single battery meets preset DC resistance test conditions is determined according to the self-discharge process data; if the to-be-tested single battery meets the preset DC resistance test conditions, the to-be-tested single battery is discharged according to a preset discharge duration to obtain discharge process data within the preset discharge duration. The preset DC resistance test conditions are used to screen the to-be-tested resistance, which can improve the test efficiency and resource utilization rate and ensure the accuracy and effectiveness of the DC resistance test data.

[0097] On the basis of the above embodiment, the present application further provides a process for determining self-discharge process data in a method for determining DC resistance of a single battery, Figure 4 A process diagram for determining self-discharge process data in a method for determining DC resistance of a single battery is provided for the embodiment of the present application, as shown in Figure 4 In step 301, the charged to-be-tested single battery is subjected to static treatment to obtain self-discharge process data of the to-be-tested single battery, which includes:

[0098] Step 401, the charged to-be-tested single battery is subjected to static treatment for a first preset duration, and a first open circuit voltage at the end of the static treatment is recorded.

[0099] The first preset duration can be any time between 4-8 hours.

[0100] Optionally, the charged to-be-tested single battery is subjected to static treatment for a first preset duration to realize depolarization treatment of the to-be-tested single battery, and a first open circuit voltage at the end of the static treatment is recorded.

[0101] Step 402, after the end of the first preset duration, the to-be-tested single battery is subjected to static treatment for a second preset duration, and a plurality of second open circuit voltages within the second preset duration are recorded.

[0102] The self-discharge process data includes the first open circuit voltage and the plurality of second open circuit voltages. The second preset duration can be 3-5 days, and the specific time is determined according to the properties of the single battery and test requirements.

[0103] Optionally, after the end of the first preset duration, the to-be-tested single battery is subjected to static treatment for a second preset duration, and a plurality of second open circuit voltages within the second preset duration are recorded, wherein each second open circuit voltage corresponds to a different discharge time.

[0104] In the embodiment of the present application, the charged single battery cell to be tested is placed for a first preset time length, and a first open circuit voltage at the end of the placement is recorded. After the first preset time length, the single battery cell to be tested is placed for a second preset time length, and a plurality of second open circuit voltages in the second preset time length are recorded. The present application can achieve a balance between rapid screening and accurate evaluation, obtain more abundant voltage variation trends, and improve the reliability and robustness of the test results.

[0105] On the basis of the above-mentioned embodiment, the present application further provides a flow of determining the preset DC internal resistance test condition in the method for determining the DC internal resistance of the single battery cell, Figure 5 For the flow of determining the preset DC internal resistance test condition in the method for determining the DC internal resistance of the single battery cell, a flowchart is provided as shown in the figure, Figure 5 In step 302, whether the single battery cell to be tested meets the preset DC internal resistance test condition is determined according to the self-discharge process data, which includes:

[0106] Step 501: obtaining a self-discharge curve of the single battery cell to be tested according to the self-discharge process data.

[0107] Optionally, the self-discharge curve of the single battery cell to be tested is obtained according to the first open circuit voltage and the plurality of second open circuit voltages in the self-discharge process data, and the time corresponding to the first open circuit voltage and the plurality of second open circuit voltages.

[0108] Step 502: determining a self-discharge rate of the single battery cell to be tested according to the self-discharge curve.

[0109] Optionally, the self-discharge rate of the single battery cell to be tested is determined according to the first open circuit voltage OCV1 and any one of the second open circuit voltages OCV2 in the self-discharge curve, and the time difference T1 of the first open circuit voltage OCV1 and any one of the second open circuit voltages OCV2, that is, k=(OCV1-OCV2) / T1.

[0110] Step 503: determining whether the self-discharge rate is less than or equal to a preset self-discharge rate threshold.

[0111] The preset self-discharge rate threshold is any one value in the range of 0.05-0.10 mV / h.

[0112] Optionally, the self-discharge rate is compared with the preset self-discharge rate threshold to determine whether the self-discharge rate is less than or equal to the preset self-discharge rate threshold.

[0113] Step 504: if the self-discharge rate is less than or equal to the preset self-discharge rate threshold, it is determined that the single battery cell to be tested meets the preset DC internal resistance test condition.

[0114] Optionally, if the self-discharge rate is less than or equal to the preset self-discharge rate threshold, it indicates that the health and stability of the to-be-tested single battery meet the detection condition, and it is determined that the to-be-tested single battery meets the preset DC resistance test condition.

[0115] In step 504, if the self-discharge rate is greater than the preset self-discharge rate threshold, it is determined that the to-be-tested single battery does not meet the preset DC resistance test condition.

[0116] Optionally, if the self-discharge rate is greater than the preset self-discharge rate threshold, it indicates that the health and stability of the to-be-tested single battery do not meet the detection condition, and it is determined that the to-be-tested single battery does not meet the preset DC resistance test condition.

[0117] In the embodiments of the present application, the self-discharge curve of the to-be-tested single battery is obtained according to the self-discharge process data, the self-discharge rate of the to-be-tested single battery is determined according to the self-discharge curve, it is determined whether the self-discharge rate is less than or equal to the preset self-discharge rate threshold, if the self-discharge rate is less than or equal to the preset self-discharge rate threshold, it is determined that the to-be-tested single battery meets the preset DC resistance test condition, and if the self-discharge rate is greater than the preset self-discharge rate threshold, it is determined that the to-be-tested single battery does not meet the preset DC resistance test condition. By setting the DC resistance test condition, the test time is significantly shortened, the production rhythm is improved, and the problem of long test time and influence on production rhythm in the traditional test method is solved.

[0118] On the basis of the above-mentioned embodiments, the present application further provides a process for determining the discharge process data in a method for determining the DC resistance of a single battery, and in step 102, the to-be-tested single battery is discharged for a preset discharge time to obtain the discharge process data within the preset discharge time, which comprises:

[0119] According to the second current density and the preset discharge time, the to-be-tested single battery is discharged by using a preset constant current discharge mode to obtain the discharge process data within the preset discharge time.

[0120] The second current density is 1-10 times the capacity of the to-be-tested single battery, and the specific current density is determined according to the test parameters. The preset discharge time is 0.5-30 seconds, and the specific discharge time is determined according to the test parameters.

[0121] Optionally, according to the second current density and the preset discharge time, the to-be-tested single battery is discharged by using a preset constant current discharge mode, which can stimulate a significant voltage signal to avoid large changes in the to-be-tested single battery, and the discharge process data within the preset discharge time is obtained.

[0122] In the embodiment of the present application, according to the second current density and the preset discharge duration, the preset constant-current discharge mode is adopted to discharge the single battery to be tested, and discharge process data in the preset discharge duration is obtained. The present application can ensure the consistency of the discharge data through the constant-current discharge, thereby improving the accuracy of the obtained discharge process data.

[0123] On the basis of the above-mentioned embodiment, the discharge process data in the preset discharge duration includes a plurality of third open circuit voltages and the first battery temperature in the preset discharge duration. For this purpose, the present application also provides a process for determining the initial DC resistance in the method for determining the DC resistance of the single battery, Figure 6 For the embodiment of the present application, a process schematic diagram for determining the initial DC resistance in the method for determining the DC resistance of the single battery is provided, as shown in Figure 6 In the step 103, the first battery temperature of the single battery to be tested at the preset discharge end time in the preset discharge duration and the initial DC resistance of the single battery to be tested are obtained according to the discharge process data.

[0124] In step 601, a discharge curve in the preset discharge duration is obtained according to the plurality of third open circuit voltages.

[0125] Optionally, according to the plurality of third open circuit voltages and the time corresponding to the open circuit voltage, a discharge curve in the preset discharge duration is obtained, with the horizontal axis being time and the vertical axis being open circuit voltage.

[0126] In step 602, the initial DC resistance is calculated according to the discharge curve.

[0127] Optionally, a target third open circuit voltage OCV3 is determined from the discharge curve, and the initial DC resistance R0=(OCV2-OCV3) / I2 is calculated according to the second open circuit voltage OCV2, the third open circuit voltage OCV3 and the second current density I2.

[0128] In the embodiment of the present application, a discharge curve in the preset discharge duration is obtained according to the plurality of third open circuit voltages, and the initial DC resistance is calculated according to the discharge curve. The present application greatly improves the accuracy, stability and information richness of the DC resistance calculation through the discharge region.

[0129] On the basis of the above-mentioned embodiment, the present application also provides a process for determining the temperature correction coefficient in the method for determining the DC resistance of the single battery, Figure 7 For the embodiment of the present application, a process schematic diagram for determining the temperature correction coefficient in the method for determining the DC resistance of the single battery is provided, as shown in Figure 7 Before the step 104, the method further includes the following steps:

[0130] Step 701, place a plurality of single cells of the same batch in an oven to obtain a plurality of single cells under a plurality of temperature gradients in a preset temperature range.

[0131] The preset temperature range can be 20-27℃. The single cells of the same batch mean that the single cells have the same properties.

[0132] Optionally, the plurality of single cells of the same batch are placed in the oven to ensure that the ambient temperatures of the plurality of single cells are consistent, and the temperature data stability is ensured by the oven, so as to obtain the plurality of single cells under the plurality of temperature gradients in the preset temperature range.

[0133] Step 702, respectively test the direct current internal resistance of the plurality of single cells under the plurality of temperature gradients to obtain the direct current internal resistance under the plurality of temperature gradients.

[0134] Optionally, the specific single cell is tested by the same direct current internal resistance test method as the above direct current internal resistance determination method, so as to obtain the direct current internal resistance under the plurality of temperature gradients, that is, the initial direct current internal resistance of the plurality of single cells of the same batch under the plurality of temperatures.

[0135] Step 703, obtain a temperature correction coefficient according to the direct current internal resistance under the plurality of temperature gradients.

[0136] Optionally, the direct current internal resistance under the plurality of temperature gradients is fitted to obtain a fitting straight line of the relationship between the temperature and the direct current internal resistance, and the slope of the fitting straight line of the relationship between the temperature and the direct current internal resistance is taken as the temperature correction coefficient.

[0137] Optionally, Figure 8 A direct current internal resistance fitting diagram of a temperature correction coefficient provided by the embodiment of the application is shown in FIG. 1. Figure 8 As shown in FIG. 1, the horizontal axis is the temperature, and the vertical axis is the direct current internal resistance value. The plurality of direct current internal resistance values under different temperatures are fitted to obtain a fitting straight line of the relationship between the temperature and the direct current internal resistance. The slope of the fitting straight line of the relationship between the temperature and the direct current internal resistance is taken as the temperature correction coefficient.

[0138] In the embodiment of the application, the plurality of single cells of the same batch are placed in the oven to obtain the plurality of single cells under the plurality of temperature gradients in the preset temperature range. The direct current internal resistance of the plurality of single cells under the plurality of temperature gradients is tested to obtain the direct current internal resistance under the plurality of temperature gradients. The temperature correction coefficient is obtained according to the direct current internal resistance under the plurality of temperature gradients. The application realizes the correction of the initial direct current internal resistance by calculating the temperature correction coefficient, improves the accuracy of the direct current internal resistance measurement, and avoids the measurement error caused by the temperature.

[0139] Based on the same inventive concept, the application also provides a single battery cell direct current resistance determination device corresponding to the single battery cell direct current resistance determination method. Since the device solves problems in the same principle as the single battery cell direct current resistance determination method, the implementation of the device can be referred to the implementation of the method, and the repeated parts will not be described here.

[0140] Figure 9 A structural schematic diagram of a single battery cell direct current resistance determination device provided by the application is shown in FIG. 1. Figure 9 As shown in the figure, the device comprises a pre-charging module 901, a discharging module 902, an acquisition module 903, and a correction module 904. The pre-charging module 901 is used to pre-charge the single battery cell to be tested, so that the single battery cell to be tested is in a preset stable state.

[0141] The discharging module 902 is used to discharge the single battery cell to be tested according to a preset discharging time, and obtain the discharging process data within the preset discharging time.

[0142] The acquisition module 903 is used to acquire the first battery cell temperature of the single battery cell to be tested at a preset discharging end time within the preset discharging time, and the initial direct current resistance of the single battery cell to be tested at the preset discharging end time according to the discharging process data.

[0143] The correction module 904 is used to correct the initial direct current resistance according to the first battery cell temperature, using a preset temperature correction coefficient of the same batch of single battery cells, to obtain the target direct current resistance of the single battery cell to be tested.

[0144] In a possible implementation, the pre-charging module 901 is specifically used to pre-charge the single battery cell to be tested in a constant current charging mode according to a first current density.

[0145] When the charging voltage of the single battery cell to be tested reaches a first preset voltage, the single battery cell to be tested is charged in a preset constant voltage charging mode until the charging current of the single battery cell to be tested is less than a preset minimum charging current.

[0146] In a possible implementation, the discharging module 902 is further used to: place the charged single battery cell to be tested for a standing treatment, and acquire self-discharging process data of the single battery cell to be tested.

[0147] According to the self-discharging process data, it is determined whether the single battery cell to be tested meets a preset direct current resistance test condition.

[0148] In a possible implementation, the discharging module 902 is specifically configured to: if the to-be-tested single battery cell satisfies the preset DC resistance test condition, discharge the to-be-tested single battery cell according to the preset discharging duration, and obtain discharging process data in the preset discharging duration.

[0149] In a possible implementation, the discharging module 902 is specifically configured to: let the to-be-tested single battery cell stand for a first preset duration after being charged, and record a first open-circuit voltage at the end of the first preset duration.

[0150] After the end of the first preset duration, let the to-be-tested single battery cell stand for a second preset duration, and record a plurality of second open-circuit voltages in the second preset duration; the self-discharging process data includes the first open-circuit voltage and the plurality of second open-circuit voltages.

[0151] In a possible implementation, the discharging module 902 is specifically configured to: obtain a self-discharging curve of the to-be-tested single battery cell according to the self-discharging process data.

[0152] Determine a self-discharging rate of the to-be-tested single battery cell according to the self-discharging curve.

[0153] Determine whether the self-discharging rate is less than or equal to a preset self-discharging rate threshold.

[0154] If the self-discharging rate is less than or equal to the preset self-discharging rate threshold, it is determined that the to-be-tested single battery cell satisfies the preset DC resistance test condition.

[0155] If the self-discharging rate is greater than the preset self-discharging rate threshold, it is determined that the to-be-tested single battery cell does not satisfy the preset DC resistance test condition.

[0156] In a possible implementation, the discharging module 902 is specifically configured to: discharge the to-be-tested single battery cell by using a preset constant-current discharging mode according to the second current density and the preset discharging duration, and obtain discharging process data in the preset discharging duration.

[0157] In a possible implementation, the discharging process data in the preset discharging duration includes a plurality of third open-circuit voltages in the preset discharging duration and the first battery cell temperature; and the discharging module 902 is specifically configured to: obtain a discharging curve of the preset discharging duration according to the plurality of third open-circuit voltages.

[0158] Calculate the initial DC resistance according to the discharging curve.

[0159] In one possible implementation, the correction module 904 is further configured to: place multiple single cells from the same batch in an oven to obtain single cells under multiple temperature gradients within a preset temperature range.

[0160] The DC internal resistance of each individual cell under the multiple temperature gradients was tested to obtain the DC internal resistance under the multiple temperature gradients.

[0161] The temperature correction coefficient is obtained based on the DC internal resistance under the multiple temperature gradients.

[0162] The processing flow of each module in the device and the interaction flow between each module can be referred to the relevant descriptions in the above method embodiments, and will not be detailed here.

[0163] This application also provides an electronic device. Figure 10 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this application, such as... Figure 10 As shown, the electronic device includes a processor 1001 and a memory 1002, and optionally, a bus 1003. The memory 1002 stores machine-readable instructions executable by the processor 1001. When the electronic device is running, the processor 1001 and the memory 1002 communicate via the bus 1003. When the machine-readable instructions are executed by the processor 1001, the steps of the method for determining the DC internal resistance of a single battery cell described above are performed.

[0164] This application also provides a computer-readable storage medium storing a computer program, which, when executed by a processor, performs the steps of the method for determining the DC internal resistance of a single battery cell.

[0165] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems and devices described above can be referred to the corresponding processes in the method embodiments, and will not be repeated here. In the several embodiments provided in this application, it should be understood that the disclosed systems, devices, and methods can be implemented in other ways. The device embodiments described above are merely illustrative. For example, the division of modules is only a logical functional division, and in actual implementation, there may be other division methods. Furthermore, multiple modules or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed mutual coupling or direct coupling or communication connection can be through some communication interfaces; the indirect coupling or communication connection of devices or modules can be electrical, mechanical, or other forms.

[0166] In addition, each function unit in each embodiment of the present application can be integrated in one processing unit, or each unit can exist physically separately, or two or more units can be integrated in one unit. When the functions are realized in the form of software function units and sold or used as an independent product, they can be stored in a computer readable storage medium. Based on this understanding, the technical solutions of the present application or the parts that essentially contribute to the prior art or the parts of the technical solutions can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes a plurality of instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: a U disk, a mobile hard disk, a read-only memory (ROM, Read-Only Memory), a random access memory (RAM, Random Access Memory), a magnetic disk or an optical disk, and various media that can store program codes.

[0167] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art can easily think of changes or replacements within the technical scope disclosed in the present application, which should be covered within the protection scope of the present application.

Claims

1. A method of determining a direct current internal resistance of a single cell, characterized by, The method comprises: a pre-charging process is performed on a to-be-tested single battery cell, so that the to-be-tested single battery cell is in a preset stable state; the to-be-tested single battery cell is discharged according to a preset discharge duration, and discharge process data within the preset discharge duration is obtained; a first battery cell temperature of the to-be-tested single battery cell at a preset discharge end time within the preset discharge duration is obtained according to the discharge process data, and an initial direct current internal resistance of the to-be-tested single battery cell at the preset discharge end time is obtained; the initial direct current internal resistance is corrected according to the first battery cell temperature and a preset temperature correction coefficient of the same batch of single battery cells, and a target direct current internal resistance of the to-be-tested single battery cell is obtained.

2. The method of claim 1, wherein, The pre-charging process performed on the to-be-tested single battery cell, so that the to-be-tested single battery cell is in a preset stable state, comprises: a pre-charging process is performed on the to-be-tested single battery cell according to a first current density by using a constant current charging mode; when a charging voltage of the to-be-tested single battery cell reaches a first preset voltage, a preset constant voltage charging mode is used to continue charging the to-be-tested single battery cell until a charging current of the to-be-tested single battery cell is less than a preset minimum charging current.

3. The method of claim 1, wherein, Before the to-be-tested single battery cell is discharged according to a preset discharge duration, the method further comprises: the to-be-tested single battery cell after charging is subjected to a standing process, and self-discharge process data of the to-be-tested single battery cell is obtained; whether the to-be-tested single battery cell satisfies a preset direct current internal resistance test condition is determined according to the self-discharge process data; the to-be-tested single battery cell is discharged according to the preset discharge duration, and discharge process data within the preset discharge duration is obtained. If the to-be-tested single battery cell satisfies the preset direct current internal resistance test condition, the to-be-tested single battery cell is discharged according to the preset discharge duration, and discharge process data within the preset discharge duration is obtained.

4. The method of claim 3, wherein, The to-be-tested single battery cell after charging is subjected to a standing process, and self-discharge process data of the to-be-tested single battery cell is obtained, comprising: the to-be-tested single battery cell after charging is subjected to a standing process for a first preset duration, and a first open circuit voltage at the end of the standing process is recorded; after the first preset duration ends, the to-be-tested single battery cell is subjected to a standing process for a second preset duration, and a plurality of second open circuit voltages within the second preset duration are recorded; the self-discharge process data comprises the first open circuit voltage and the plurality of second open circuit voltages.

5. The method of claim 3, wherein, whether the to-be-tested single battery cell satisfies a preset direct current internal resistance test condition is determined according to the self-discharge process data, comprising: a self-discharge curve of the to-be-tested single battery cell is obtained according to the self-discharge process data; a self-discharge rate of the to-be-tested single battery cell is determined according to the self-discharge curve; whether the self-discharge rate is less than or equal to a preset self-discharge rate threshold is determined; if the self-discharge rate is less than or equal to the preset self-discharge rate threshold, it is determined that the to-be-tested single battery cell satisfies the preset direct current internal resistance test condition; If the self-discharge rate is greater than the preset self-discharge rate threshold, then the single cell under test is determined not to meet the preset DC internal resistance test conditions.

6. The method of claim 1, wherein, The step of discharging the single cell under test according to a preset discharge duration to obtain discharge process data within the preset discharge duration includes: Based on the second current density and the preset discharge duration, the single cell to be tested is discharged using a preset constant current discharge method to obtain discharge process data within the preset discharge duration.

7. The method of claim 6, wherein, The discharge process data within the preset discharge duration includes: multiple third open-circuit voltages and the temperature of the first cell within the preset discharge duration; The step of obtaining the first cell temperature of the single cell under test at the preset discharge end time within the preset discharge duration, and the initial DC internal resistance of the single cell under test based on the discharge process data includes: Based on the plurality of third open-circuit voltages, the discharge curve of the preset discharge duration is obtained; Calculate the initial DC internal resistance based on the discharge curve.

8. The method of claim 1, wherein, Before correcting the initial DC internal resistance based on the temperature of the first cell using a preset temperature correction coefficient for individual cells from the same batch, and obtaining the target DC internal resistance of the individual cell to be tested, the method further includes: Multiple individual battery cells from the same batch are placed in an oven to obtain individual battery cells under multiple temperature gradients within a preset temperature range. The DC internal resistance of each individual cell under the multiple temperature gradients was tested to obtain the DC internal resistance under the multiple temperature gradients. The temperature correction coefficient is obtained based on the DC internal resistance under the multiple temperature gradients.

9. A device for determining the DC internal resistance of a single battery cell, characterized in that, The device includes: The pre-charge module is used to pre-charge the single cell under test, so that the single cell under test is in a preset stable state. The discharge module is used to discharge the single cell under test according to a preset discharge duration to obtain discharge process data within the preset discharge duration. The acquisition module is used to acquire, based on the discharge process data, the first cell temperature of the cell under test at the preset discharge end time within the preset discharge duration, and the initial DC internal resistance of the cell under test at the preset discharge end time. The correction module is used to correct the initial DC internal resistance based on the temperature of the first cell and a preset temperature correction coefficient for individual cells in the same batch, so as to obtain the target DC internal resistance of the individual cell to be tested.

10. An electronic device, comprising: include: The device includes a processor and a memory, the memory storing machine-readable instructions executable by the processor, which, when the electronic device is in operation, are executed by the processor to perform the steps of the method for determining the DC internal resistance of a single battery cell as described in any one of claims 1 to 8.

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