Battery detection equipment

Abstract

The invention discloses battery detection equipment, and the equipment comprises a test module which is used for carrying out the impedance test of a to-be-detected battery, and obtaining an impedance test result of the to-be-detected battery; the signal collection module is used for calculating the impedance value of the to-be-tested battery according to the impedance test result of the to-be-tested battery obtained from the test module; the signal processing and feedback module is used for calculating the capacitance value of the to-be-measured battery according to the impedance value of the to-be-measured battery acquired from the signal collection module; and calculating the battery capacity of the to-be-measured battery according to a predetermined corresponding relation between the capacitance value and the battery capacity. The purpose of the present application is to safely and efficiently measure the capacity of a battery.

Description

Technical Field

[0001] The present application belongs to the field of battery technology, and specifically relates to a battery testing device. Background Art

[0002] With the increasing use of secondary batteries, represented by lithium-ion batteries, in areas such as electric vehicles, wearable devices, and energy storage systems, the requirements for battery performance and safety are also increasing. Battery capacity testing is a key means of ensuring battery performance and safety. For example, during the battery production process, capacity testing is required. Through capacity testing, key parameters such as battery capacity, internal resistance, and energy density can be measured to ensure that the battery's performance and quality meet standards. For example, during battery use, by testing the battery capacity, combining parameters such as battery voltage, current, and temperature, and further using intelligent algorithms to accurately analyze the battery status, it is possible to predict the battery's remaining life and assess its health status, thereby formulating more reasonable charging and discharging strategies and maintenance plans.

[0003] However, traditional testing equipment typically uses a constant current charge-discharge method, charging and discharging the battery with a constant current to measure battery capacity. However, traditional testing takes a long time to complete a complete capacity test or battery status analysis, resulting in low production and testing efficiency and increased costs. Furthermore, prolonged high-current charge and discharge can cause battery temperatures to rise, potentially leading to safety issues. Summary of the Invention

[0004] To solve the above problems, the present application provides a battery testing device, which aims to safely and efficiently measure the capacity of the battery.

[0005] The present application provides a battery testing device, comprising:

[0006] The test module is used to perform an impedance test on the battery to be tested and obtain the impedance test result of the battery to be tested;

[0007] A signal collection module is used to calculate the impedance value of the battery to be tested based on the impedance test result of the battery to be tested obtained from the test module;

[0008] The signal processing and feedback module is used to calculate the capacitance value of the battery to be tested based on the impedance value of the battery to be tested obtained from the signal collection module; and calculate the battery capacity of the battery to be tested based on the predetermined corresponding relationship between the capacitance value and the battery capacity.

[0009] The battery detection device of the embodiment of the present application can perform an impedance test on the battery to be tested through the test module to obtain the impedance test result of the battery to be tested. Through the signal collection module, the impedance value of the battery to be tested is calculated based on the impedance test result of the battery to be tested obtained from the test module. Through the signal processing and feedback module, the capacitance value of the battery to be tested is calculated based on the impedance value of the battery to be tested obtained from the signal collection module; and the battery capacity of the battery to be tested is calculated based on the predetermined correspondence between the capacitance value and the battery capacity. According to the embodiment of the present application, based on the pre-established correspondence between the capacitance value and the battery capacity, the battery detection device can complete a single capacity test of the battery to be tested in just a few seconds. In this way, not only can the time of the battery capacity test be significantly reduced and the consumption of the battery capacity test be reduced, but also the safety hazards caused by long-term high-current charging and discharging can be avoided, thereby safely and efficiently measuring the capacity of the battery. As a result, the test efficiency and safety of battery capacity classification or status analysis can be improved.

[0010] In any embodiment of the present application, the test module includes:

[0011] The swept frequency impedance test submodule is used to perform a swept frequency impedance test on the battery to be tested within a preset frequency range and obtain the swept frequency impedance test results;

[0012] The single-frequency impedance test submodule is used to perform a single-frequency impedance test on the battery to be tested in a non-charging and discharging state at a target frequency to obtain a single-frequency impedance test result. The target frequency is determined according to the swept-frequency impedance test result.

[0013] In any embodiment of the present application, the test module further includes:

[0014] The current-carrying impedance test submodule is used to perform a single-frequency impedance test on the battery under test in the charge and discharge state at the target frequency to obtain the current-carrying impedance test result.

[0015] In any embodiment of the present application, the device further includes:

[0016] The bias voltage / bias current module is used to adjust the charging current and discharging current of the battery under test.

[0017] In any embodiment of the present application, the test module further includes:

[0018] The frequency adjustment submodule is used to adjust the test frequency of the swept frequency impedance test and the single frequency impedance test.

[0019] In any embodiment of the present application, the test frequency adjustment range of the adjustment submodule is 100 kHz to 1 Hz, and the adjustment step is 0.1 Hz.

[0020] In any embodiment of the present application, the signal processing and feedback module is further configured to analyze the status information of the battery to be tested according to the battery capacity of the battery to be tested.

[0021] In any embodiment of the present application, the battery to be tested includes a lithium-ion battery;

[0022] A signal collection module, configured to calculate an impedance value sequence of the battery under test during the preset period based on the current-carrying impedance test results of the battery under test during the preset period obtained from the test module;

[0023] A signal processing and feedback module is used to calculate the capacitance value sequence of the battery to be tested in the preset time period based on the impedance value sequence in the preset time period obtained from the signal collection module;

[0024] The signal processing and feedback module is further used to determine the lithium plating status information of the battery to be tested based on the capacitance value sequence of the battery to be tested in a preset time period.

[0025] In any embodiment of the present application, the device further includes a bias voltage / bias current module for stopping charging and discharging the battery to be tested in response to target lithium deposition status information sent by the signal processing and feedback module, wherein the target lithium deposition status information is used to characterize the occurrence of lithium deposition in the battery to be tested.

[0026] In any embodiment of the present application, the device further includes:

[0027] The electromagnetic shielding module is used to shield the influence of electromagnetic induction on the test module.

[0028] In any embodiment of the present application, the testing module is further configured to perform impedance testing on a plurality of calibration batteries to obtain impedance test results of each calibration battery;

[0029] The signal collection module is further used to calculate the impedance value of each calibration battery according to the impedance test results of each calibration battery obtained from the test module;

[0030] The signal processing and feedback module is also used to calculate the capacitance value of each calibration battery based on the impedance value of each calibration battery obtained from the signal collection module; and determine the corresponding relationship between the capacitance value and the battery capacity based on the predetermined battery capacity of each calibration battery and the capacitance value of each calibration battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A schematic diagram of the structure of a battery testing device provided in one embodiment of the present application;

[0032] Figure 2 A schematic diagram of changes in battery capacitance values collected by a battery testing device provided in one embodiment of the present application during lithium deposition testing of the battery of Example 1;

[0033] Figure 3 This is an in-situ SEM image of the battery of Example 1 of the present application after being charged to 0.6 Ah;

[0034] Figure 4 Schematic diagram of the fitting results of the battery capacitance and capacity of Example 2 of the present application. DETAILED DESCRIPTION

[0035] In order to make the application purpose, technical solution and beneficial technical effects of this application clearer, the application is further described in detail below with reference to the embodiments. It should be understood that the embodiments described in this specification are only for explaining this application and are not intended to limit this application.

[0036] For simplicity, this application only explicitly discloses certain numerical ranges. However, any lower limit may be combined with any upper limit to form an unspecified range; and any lower limit may be combined with other lower limits to form an unspecified range, and similarly, any upper limit may be combined with any other upper limit to form an unspecified range. In addition, although not explicitly stated, each point or individual value between the endpoints of a range is included in the range. Thus, each point or individual value may serve as its own lower limit or upper limit and be combined with any other point or individual value, or with other lower limits or upper limits, to form an unspecified range.

[0037] In the description of this application, it should be noted that, unless otherwise specified, “above” and “below” are inclusive of the number, and “a variety” in “one or more” means two or more.

[0038] The above disclosure of the present application is not intended to describe every disclosed embodiment or every implementation in the present application. The following description more specifically illustrates exemplary embodiments. In many places throughout the application, guidance is provided through a series of examples, which can be used in various combinations. In each example, the enumeration is intended only as a representative group and should not be construed as exhaustive.

[0039] As described in the background, traditional testing equipment typically uses a constant current charge-discharge method, charging and discharging the battery with a constant current to measure the battery's capacity. However, traditional testing requires a long time to complete a complete capacity test or battery status analysis, resulting in low production and testing efficiency and increased costs. Furthermore, prolonged high-current charge and discharge can cause the battery to heat up and even pose safety risks.

[0040] In view of this, the inventors have provided a battery testing device after in-depth research and extensive experiments.

[0041] The following describes the battery testing device provided in the embodiments of the present application through specific embodiments and their application scenarios, in conjunction with the accompanying drawings. The battery testing device provided in the embodiments of the present application can be used independently for battery testing, or it can be integrated into a battery management system (BMS) and combined with other functions of the BMS to implement battery testing.

[0042] The present application provides a battery testing device. Figure 1 FIG. 1 shows a schematic diagram of the structure of a battery detection device provided by an embodiment of the present application. Figure 1 As shown, the battery testing device 100 may include a testing module 101 , a signal collecting module 102 , and a signal processing and feedback module 103 .

[0043] The testing module 101 is used to perform an impedance test on the battery to be tested and obtain an impedance test result of the battery to be tested.

[0044] In the present application, the battery to be tested may include but is not limited to lithium-ion batteries, sodium-ion batteries, and other batteries that realize charging and discharging by embedding and extracting active ions (such as lithium ions or sodium ions) between the positive and negative electrodes. The battery to be tested may be a battery at any stage in the battery life cycle, for example, it may be a battery before formation or a battery after formation, it may be a battery after storage for a period of time, or it may be a battery after circulation for a certain period of time. The battery to be tested may be a battery of any model and specification, for example, it may include a soft-pack battery or a hard-shell battery; it may include a battery with a winding structure or a battery with a laminated structure; it may include a cylindrical battery or a square-shell battery, and so on. Accordingly, the battery testing equipment may include a battery tray for carrying the battery to be tested. In one example, the battery tray is an adjustable tray, so that the configuration of the battery tray can be adaptively changed for different types of batteries.

[0045] The signal collection module 102 is configured to calculate the impedance value of the battery to be tested based on the impedance test result of the battery to be tested obtained from the testing module 101 .

[0046] Specifically, the testing module 101 performs an impedance test on the battery to be tested and can obtain voltage and current data during the impedance test. The signal collection module 102 can determine the impedance value of the battery to be tested by analyzing the voltage and current data during the impedance test.

[0047] The signal processing and feedback module 103 is used to calculate the capacitance value of the battery under test according to the impedance value of the battery under test obtained from the signal collection module 102; and calculate the battery capacity of the battery under test according to the predetermined corresponding relationship between the capacitance value and the battery capacity.

[0048] The predetermined correspondence between the capacitance value and the battery capacity may be pre-stored in the signal processing and feedback module 103. As an example, the correspondence may be a correspondence fitted and stored by the signal processing and feedback module 103 based on the capacitance values of multiple batteries with known capacity information. As another example, the correspondence may be a correspondence input by the user to the signal processing and feedback module 103.

[0049] The corresponding relationship between the above-mentioned capacitance value and the battery capacity can be a linear relationship, or it can be the corresponding relationship between the capacitance value and the battery capacity fitted by a machine learning algorithm. As an example, the above-mentioned corresponding relationship is a linear relationship, and the signal processing and feedback module 103 can substitute the capacitance value of the battery to be tested into the linear relationship equation to calculate the battery capacity corresponding to the capacitance value of the battery to be tested. As another example, the above-mentioned corresponding relationship is the corresponding relationship between the capacitance value and the battery capacity fitted by a machine learning algorithm, and the signal processing and feedback module 103 can input the capacitance value of the battery to be tested into the trained battery capacity analysis model, and by the battery capacity analysis model, according to the corresponding relationship between the capacitance value and the battery capacity fitted in advance, calculate and output the battery capacity corresponding to the capacitance value of the battery to be tested.

[0050] Without intending to be bound by any theory or explanation, the inventors of the present application have discovered that the capacitance value of the above-mentioned type of battery is related to the degree of embedding of active ions in the negative electrode. For example, in a lithium-ion battery, as lithium ions are embedded, the surface area of the graphite negative electrode and other factors will change, thereby causing a change in the battery capacitance value. The change in battery capacity is directly related to the degree of lithium embedding in the negative electrode. It can be seen that there is a specific corresponding relationship between the capacitance value of the battery and the capacity of the battery. After further research, the inventors found that there is a linear correlation between the capacitance value of the above-mentioned type of battery and the battery capacity.

[0051] The battery detection device 100 of the embodiment of the present application can perform an impedance test on the battery to be tested through the test module 101 to obtain the impedance test result of the battery to be tested. Through the signal collection module 102, the impedance value of the battery to be tested is calculated based on the impedance test result of the battery to be tested obtained from the test module 101. Through the signal processing and feedback module 103, the capacitance value of the battery to be tested is calculated based on the impedance value of the battery to be tested obtained from the signal collection module 102; and the battery capacity of the battery to be tested is calculated based on the predetermined correspondence between the capacitance value and the battery capacity. According to the embodiment of the present application, based on the pre-established correspondence between the capacitance value and the battery capacity, the battery detection device can complete a single capacity test of the battery to be tested in just a few seconds. In this way, not only can the time of the battery capacity test be significantly reduced and the consumption of the battery capacity test be reduced, but also the safety hazards caused by long-term high-current charging and discharging can be avoided, thereby safely and efficiently measuring the capacity of the battery. As a result, the test efficiency and safety of battery capacity classification or status analysis can be improved.

[0052] In some embodiments, when the battery testing device 100 is used for rapid battery capacity sizing, the battery to be tested may include a battery that has been prepared but has not yet been formed or subjected to charge and discharge cycles. According to the battery testing device 100 of the present application, the capacity of the battery to be tested can be determined simply by measuring the capacitance of the battery to be tested in an uncharged or undischarged state, or in the presence of a microcurrent disturbance, without requiring charging or discharging. Therefore, capacity sizing can be performed before the battery to be tested is formed, thereby improving the efficiency of battery capacity sizing.

[0053] In some embodiments, the testing module 101 may specifically include:

[0054] The swept frequency impedance test submodule is used to perform a swept frequency impedance test on the battery to be tested within a preset frequency range to obtain the swept frequency impedance test results.

[0055] The single-frequency impedance test submodule is used to perform a single-frequency impedance test on the battery to be tested in a non-charging and discharging state at a target frequency to obtain a single-frequency impedance test result. The target frequency is determined according to the swept-frequency impedance test result.

[0056] In the above embodiment, the preset frequency range may include a frequency range input by a user to the battery testing device 100 , or may include a frequency range determined according to the type information of the battery to be tested based on a pre-stored correspondence between battery type information and frequency ranges.

[0057] The target frequency can be the characteristic frequency of the battery under test, specifically the frequency value corresponding to the maximum absolute value of the imaginary part of the impedance in the swept-frequency impedance test results. The target frequency can be a frequency determined and input by the user based on the swept-frequency impedance test results, or it can be a frequency determined by the battery testing device 100 based on the swept-frequency impedance test results. For example, the signal collection module 102 can obtain the swept-frequency impedance test results of the battery under test, and the signal processing and feedback module 103 can determine the target frequency of the battery under test based on the swept-frequency impedance test results obtained from the signal collection module 102, and feed it back to the testing module 101.

[0058] According to the above embodiment, the testing module 101 can first perform a swept-frequency impedance test on the battery under test, and then perform a single-frequency impedance test on the battery under test at a target frequency determined based on the swept-frequency impedance test results. In this way, performing a single-frequency impedance test at the characteristic frequency of the battery under test can improve the accuracy of the single-frequency impedance test results, thereby improving the accuracy of the battery capacity measurement.

[0059] In some embodiments, the testing module 101 may further include:

[0060] The current-carrying impedance test submodule is used to perform a single-frequency impedance test on the battery under test in the charge and discharge state at the target frequency to obtain the current-carrying impedance test result.

[0061] In the above embodiment, the charge and discharge state may include a charge and discharge cycle state, or a state in which a short current flows. In one example, the battery testing device 100 may include a power supply for providing a DC charge / discharge current to the battery under test. In another example, the battery testing device 100 may be integrated into a battery management system (BMS) and provide a DC charge / discharge current to the battery under test by invoking the BMS's power module.

[0062] According to the above embodiment, the testing module 101 can perform a single-frequency impedance test on the battery under test in the charge and discharge state, obtain the current-carrying impedance test result, and then obtain the battery capacity of the battery under test in the charge and discharge state. In this way, the capacitance value and capacity of the battery under test can be monitored and analyzed in real time during the operation of the battery under test, which is conducive to preventing battery failure and improving battery safety.

[0063] In combination with the technical solutions of the battery testing device 100 performing impedance testing in the above embodiments, after the signal processing and feedback module 103 obtains the impedance value of the battery to be tested from the signal collection module 102, the capacitance value of the battery to be tested can be calculated by Formula 1.

[0064]

[0065] In Equation 1, C represents the capacitance of the battery; f represents the characteristic frequency value corresponding to the battery (i.e., the target frequency); and Z' represents the imaginary part of the impedance of the calibrated battery.

[0066] In some embodiments, the battery testing device 100 may further include:

[0067] The bias voltage / bias current module is used to adjust the charging current and discharging current of the battery under test.

[0068] The bias voltage / bias current module can achieve the above functions by controlling the power supply in the battery testing device 100 that provides DC charge / discharge current to the battery under test. Alternatively, the bias voltage / bias current module can achieve the above functions by invoking the power supply module of the BMS. This facilitates flexible adjustment of the charge and discharge state of the battery under test, balancing normal operation and capacity testing of the battery under test.

[0069] In some embodiments, the testing module 101 may further include:

[0070] The frequency adjustment submodule is used to adjust the test frequency of the swept frequency impedance test and the single frequency impedance test.

[0071] Specifically, the frequency adjustment submodule can adjust the preset frequency range in the swept-frequency impedance test based on a frequency range input by the user, or based on a pre-stored correspondence between battery type information and frequency range, and according to the frequency range determined by the type information of the battery to be tested. The frequency adjustment submodule can also adjust the test frequency of the single-frequency impedance test to the target frequency. The process of determining the target frequency has been described in detail above and will not be repeated here.

[0072] In some embodiments, the test frequency adjustment range of the adjustment submodule can be 100 kHz to 1 Hz, and the adjustment step can be 0.1 Hz.

[0073] In some embodiments, the signal processing and feedback module 103 may also be configured to analyze the status information of the battery under test according to the battery capacity of the battery under test.

[0074] The above-mentioned status information may include the remaining capacity of the battery, such as SOC, SOH, etc. In some examples, in addition to the battery capacity, the battery voltage, current, temperature and other parameters can also be monitored in real time, and the battery status can be accurately analyzed in combination with intelligent algorithms to predict the remaining life of the battery, evaluate the health status of the battery, and then formulate a more reasonable charging and discharging strategy and maintenance plan. The above-mentioned voltage, current, temperature and other parameters can be obtained by the battery detection device 100 based on preset sensors and voltage / current signal monitoring modules through the signal collection module 102, or they can be directly obtained by the battery detection device 100 from external devices such as BMS through the signal collection module 102, which is not limited here.

[0075] In some embodiments, the battery under test comprises a lithium-ion battery.

[0076] The signal collection module 102 may be specifically configured to calculate an impedance value sequence of the battery under test during the preset period according to the current-carrying impedance test result of the battery under test during the preset period obtained from the test module.

[0077] The signal processing and feedback module 103 may be specifically configured to calculate a capacitance value sequence of the battery to be tested in a preset period of time based on the impedance value sequence in the preset period of time obtained from the signal collection module.

[0078] The signal processing and feedback module 103 may also be used to determine the lithium deposition status information of the battery under test according to the capacitance value sequence of the battery under test in a preset time period.

[0079] In the above embodiment, the preset time period can be set according to the need for battery performance monitoring, for example, it can be the past month, the past week, the past three days, the current day, the five hours closest to the current time, etc. The preset time period can also be set according to the number of battery cycles, for example, it can be nearly 100 cycles, 200 cycles, 500 cycles, 1000 cycles, etc. The impedance value sequence can include multiple impedance values arranged in time sequence and containing time information. The capacitance value sequence can include multiple capacitance values arranged in time sequence and containing time information.

[0080] Lithium deposition is a common safety hazard in lithium-ion batteries during use. When lithium deposition occurs within a battery, lithium metal deposits on the negative electrode surface. This not only reduces the battery's energy density and cycle life, but can also cause serious problems such as internal short circuits and thermal runaway. Therefore, real-time monitoring and analysis of lithium deposition in lithium-ion batteries is crucial for preventing battery failure and improving battery safety. Traditional testing equipment is often limited to single tests or analyses, such as capacity testing or status analysis, which cannot meet the needs of comprehensive battery performance evaluation.

[0081] Without intending to be bound by any theory or explanation, the inventors have discovered that when lithium deposition occurs in the negative electrode of a lithium-ion battery, such as a graphite negative electrode, the electrode surface area rapidly increases, causing the electrode capacitance to increase significantly, thereby causing the battery capacitance to increase significantly. Therefore, the lithium deposition of the battery can be determined by monitoring the capacitance value of the battery. According to the above embodiment, the capacitance value of the battery to be tested can be monitored during the charge and discharge cycle. Thus, the lithium deposition of the battery can be accurately determined based on the sudden change in the capacitance value of the battery to be tested, thereby reducing the safety risk of battery operation.

[0082] In addition, the battery testing device 100 according to the above embodiment can complete multiple tests such as lithium deposition, capacity separation, and status analysis at one time, which greatly shortens the test cycle and improves the test efficiency.

[0083] In some embodiments, the bias voltage / bias current module can also be used to stop charging and discharging the battery under test in response to the target lithium deposition state information sent by the signal processing and feedback module 103. The target lithium deposition state information is used to indicate that lithium deposition occurs in the battery under test.

[0084] In the above embodiment, the bias voltage / bias current module can control the power supply to be disconnected or stop calling the power module of the BMS, thereby stopping the charging and discharging of the battery under test. In this way, the circuit can be disconnected in time when lithium deposition occurs in the battery, thereby preventing problems such as internal short circuits and thermal runaway of the battery and reducing safety risks.

[0085] In some embodiments, the battery testing device 100 may further include:

[0086] The electromagnetic shielding module is used to shield the influence of electromagnetic induction on the test module.

[0087] In this way, the accuracy of the impedance test result can be improved.

[0088] In some embodiments, the testing module 101 is further configured to perform impedance testing on a plurality of calibration batteries to obtain impedance test results of each calibration battery.

[0089] The signal collection module 102 is further configured to calculate the impedance value of each calibrated battery according to the impedance test result of each calibrated battery obtained from the testing module 101 .

[0090] The signal processing and feedback module 103 is further used to calculate the capacitance value of each calibration battery based on the impedance value of each calibration battery obtained from the signal collection module 102; and determine the corresponding relationship between the capacitance value and the battery capacity based on the predetermined battery capacity of each calibration battery and the capacitance value of each calibration battery.

[0091] In the above embodiment, the calibration battery can be a battery of known capacity. The capacity of the calibration battery can be measured by a constant current charge and discharge method. Specifically, the calibration battery can be charged to a charge cut-off voltage at a constant current of 0.1C to 1C (for example, a constant current of 0.2C), and then discharged to a discharge cut-off voltage at a constant current. The battery capacity of the calibration battery is determined based on the charge and discharge curve. It is understandable that the battery capacity of the above-mentioned calibration battery can be input into the battery testing device 100 by the user based on the test results of the constant current charge and discharge method, or can be determined by the battery testing device 100 by performing constant current charge and discharge on the calibration battery.

[0092] In some examples, the calibration battery can be a battery that uses the same types of battery materials and has the same structure as the battery under test. The same types of battery materials used in the calibration battery as in the battery under test can mean that the types of positive active materials, negative active materials, and electrolyte systems used in the calibration battery are the same as those in the battery under test. For example, the positive active materials are all lithium iron phosphate, the negative active materials are all carbon materials, and the electrolytes are all carbonate electrolytes, etc. The same structure in the calibration battery as in the battery under test can mean that both the calibration battery and the battery under test are laminated batteries or wound batteries. When both are laminated batteries, the number and arrangement of positive and negative electrode plates are the same; when both are wound batteries, the number of windings is the same. In some examples, the calibration battery can be a battery with the same specifications as the battery under test. The same specifications in the calibration battery as in the battery under test can mean that the types of battery materials used in the calibration battery and their proportions are the same as those in the battery under test, and the structure of the calibration battery is also the same as that of the battery under test. In this way, the calibration battery and the battery under test are similar batteries, and both have basically the same capacitance value and battery capacity correspondence. Based on the capacitance values and battery capacities of multiple calibration batteries, the capacitance value and battery capacity correspondence is determined, and when used in the test of the battery under test, it helps to improve the accuracy of the test results.

[0093] In the above embodiment, the implementation of the impedance test of the calibration battery may be the same as the impedance test of the battery to be tested. The various implementations of the impedance test of the battery to be tested have been described above and will not be repeated here.

[0094] Example

[0095] The following examples more particularly describe the present disclosure, and these examples are intended to be illustrative only, as various modifications and variations within the scope of the present disclosure will be apparent to those skilled in the art. Unless otherwise indicated, all parts, percentages, and ratios reported in the following examples are by weight, and all reagents used in the examples are commercially available or synthesized according to conventional methods and used directly without further processing, and all instruments used in the examples are commercially available.

[0096] Example 1

[0097] Lithium iron phosphate (LiFePO4, LFP)-graphite full battery lithium plating detection

[0098] (1) Assembly of LFP-graphite full battery: The graphite negative electrode uses mesophase carbon microbeads (MCMB), and the MCMB: conductive carbon black (Supper P): polyvinylidene fluoride (PVDF) mass ratio is 8:1:1 and mixed with an appropriate amount of N-methylpyrrolidone (NMP) to obtain a negative electrode slurry. After the negative electrode slurry is coated on the copper foil, it is dried in a blast dryer for 24 hours to obtain a negative electrode sheet. LFP is selected as the positive electrode material, and the LFP: conductive carbon black: PVDF mass ratio is 9:0.5:0.5 and mixed with an appropriate amount of NMP to obtain a positive electrode slurry. The positive electrode slurry is coated on the surface of the aluminum foil and dried in a blast drying oven for 24 hours to obtain a surface capacity of 2mA h cm -2 The positive electrode is made of PE. The separator is made of PE. The electrolyte is 1 mol / L lithium hexafluorophosphate (LiPF6) and the electrolyte solvent is a mixed solvent of ethylene carbonate / ethyl methyl carbonate (EC / EMC, volume ratio of 1:2).

[0099] (2) Battery formation and capacity test: The assembled battery is given a formation current of 0.05 to stimulate the active materials in the positive and negative electrodes of the battery, giving the battery discharge capability. A constant current charge and discharge test of 0.05C is then performed to obtain the battery capacity information.

[0100] (3) Battery capacitance test: Perform a sweep frequency impedance test with the battery detection equipment to obtain the characteristic frequency, and then perform a characteristic frequency fixed frequency current impedance test to obtain the battery impedance information. Calculate the battery capacitance value based on the impedance data, such as Figure 2 shown.

[0101] (4) Determination of lithium plating: During normal battery charging, the battery capacitance increases slowly; when lithium plating occurs, the battery capacitance increases rapidly. Based on this principle, the battery detection equipment can determine Figure 2 The battery shown in the figure undergoes lithium deposition after being charged to 0.6Ah. The in-situ SEM test of the negative electrode surface of the battery shows the following Figure 3 The in-situ SEM image of the battery after charging to 0.6Ah is shown. Figure 3 It can be seen that lithium plating has occurred on the surface of the negative electrode of the battery. It can be seen that the battery detection equipment can accurately identify the lithium plating phenomenon of the battery based on the change of the battery capacitance value.

[0102] Example 2

[0103] Ternary materials (LiNi 0.8 Co 0.1 Mn 0.1 O2, NCM811)-graphite full battery capacity

[0104] (1) Assembly of NCM811-graphite full battery: The graphite negative electrode uses mesophase carbon microbeads (MCMB), which are mixed evenly with an appropriate amount of N-methylpyrrolidone (NNMP) in a mass ratio of 8:1:1 of MCMB: conductive carbon black (Supper P): polyvinylidene fluoride (PVDF) to obtain a negative electrode slurry. After the negative electrode slurry is coated on copper foil, it is dried in a blast dryer for 24 hours to obtain a negative electrode sheet. The ternary material NCM811 is selected as the positive electrode material, and the positive electrode slurry is mixed evenly with an appropriate amount of NMP in a mass ratio of 9:0.5:0.5 of NCM811: conductive carbon black: PVDF to obtain a positive electrode slurry. The positive electrode slurry is coated on the surface of aluminum foil and dried in a blast drying oven for 24 hours to obtain a surface capacity of 2 mA h cm -2 The positive electrode is made of PE. The diaphragm is made of PE. The electrolyte is 1 mol / L LiPF6, and the electrolyte solvent is a mixed solvent of ethylene carbonate and ethyl methyl carbonate (EC / EMC, volume ratio of 1:2).

[0105] (2) Battery formation and capacity test: The assembled battery is given a formation current of 0.05C to stimulate the active materials in the positive and negative electrodes of the battery, giving the battery discharge capability. A charge and discharge test of 0.05C is then performed to obtain the battery capacity information.

[0106] (3) Battery capacitance test: After the battery has been tested for capacity, a swept frequency impedance test is performed using battery testing equipment to obtain the characteristic frequency, and then a characteristic frequency fixed frequency impedance test is performed to obtain the battery impedance information. The corresponding capacitance value is calculated based on the impedance imaginary part data.

[0107] (4) Capacity division results: There is a linear correlation between battery capacitance and battery capacity. Figure 4 As shown, the battery detection equipment can calculate the battery capacity value according to the battery capacitance test results, thereby realizing battery capacity classification.

[0108] Example 3

[0109] LFP-graphite full battery status assessment

[0110] (1) Assembly of LFP-graphite full battery: The graphite negative electrode uses mesophase carbon microbeads (MCMB), and the MCMB: conductive carbon black (Supper P): polyvinylidene fluoride (PVDF) mass ratio is 8:1:1 and mixed with an appropriate amount of N-methylpyrrolidone (NNMP) to obtain a negative electrode slurry. After the negative electrode slurry is coated on the copper foil, it is dried in a blast dryer for 24 hours to obtain a negative electrode sheet. LFP is selected as the positive electrode material, and the LFP: conductive carbon black: PVDF mass ratio is 9:0.7:0.3 and mixed with an appropriate amount of NMP to obtain a positive electrode slurry. The positive electrode slurry is coated on the surface of the aluminum foil and dried in a blast drying oven for 24 hours to obtain a surface capacity of 2mA h cm -2 The positive electrode is made of PE. The separator is made of PE. The electrolyte is 1 mol / L lithium hexafluorophosphate (LiPF6) and the electrolyte solvent is a mixed solvent of ethylene carbonate / ethyl methyl carbonate (EC / EMC, volume ratio of 1:2).

[0111] (2) Battery formation and capacity test: The assembled battery is given a formation current of 0.05C to stimulate the active materials in the positive and negative electrodes of the battery, giving the battery discharge capability. A charge and discharge test of 0.05C is then performed to obtain the battery capacity information.

[0112] (3) Battery cycle and capacitance test: After the battery has been tested for capacity, it is cycled at 1C. After every ten cycles, a sweep frequency impedance test is performed using the battery testing equipment to obtain the characteristic frequency, and then a characteristic frequency fixed frequency current impedance test is performed to obtain the battery impedance information. The battery capacitance is calculated based on the impedance data. At the same time, after every ten cycles, a 0.05C charge and discharge test is performed to obtain the battery capacity information.

[0113] (4) Battery status assessment results: The battery testing equipment can calculate the battery capacity based on the battery capacitance. As shown in Table 1, the relative error between the calculated capacity and the actual battery capacity is less than 1%. Therefore, the battery testing equipment can accurately determine the remaining capacity of the battery after a certain number of cycles, thereby assessing the battery status.

[0114] Table 1

[0115] Number of cycles Actual capacity (Ah) Test capacitance (F) Calculated capacity (Ah) Relative error (%) 0 1.061 11.985 1.062 0.077 10 1.054 12.050 1.053 0.046 20 1.046 12.093 1.047 0.125 30 1.038 12.172 1.036 0.162 40 1.027 12.227 1.028 0.159 50 1.020 12.283 1.020 0.049 60 1.010 12.365 1.009 0.136_ 70 1.004 12.385 1.006 0.243_ 80 0.996 12.439 0.999 0.235 90 0.987 12.535 0.985 0.225 100 0.981 12.553 0.983 0.176

[0116] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present application, and such modifications or substitutions are intended to be included within the scope of protection of the present application. Therefore, the scope of protection of the present application shall be subject to the scope of protection of the claims.

Claims

1. A battery testing device, characterized in that: include: A testing module, configured to perform an impedance test on a battery to be tested and obtain an impedance test result of the battery to be tested; a signal collection module, configured to calculate the impedance value of the battery to be tested based on the impedance test result of the battery to be tested obtained from the test module; The signal processing and feedback module is used to calculate the capacitance value of the battery to be tested based on the impedance value of the battery to be tested obtained from the signal collection module; and calculate the battery capacity of the battery to be tested based on a predetermined correspondence between the capacitance value and the battery capacity.

2. The device according to claim 1, characterized in that The test module includes: A swept frequency impedance test submodule, configured to perform a swept frequency impedance test on the battery to be tested within a preset frequency range to obtain a swept frequency impedance test result; The single-frequency impedance test submodule is used to perform a single-frequency impedance test on the battery to be tested in a non-charging and discharging state at a target frequency to obtain a single-frequency impedance test result, wherein the target frequency is determined according to the swept-frequency impedance test result.

3. The device according to claim 2, characterized in that The test module also includes: The current-carrying impedance test submodule is used to perform a single-frequency impedance test on the battery to be tested in the charge and discharge state at the target frequency to obtain a current-carrying impedance test result.

4. The device according to claim 3, characterized in that The device further comprises: The bias voltage / bias current module is used to adjust the charging current and discharging current of the battery to be tested.

5. The device according to any one of claims 2 to 4, characterized in that The test module also includes: The frequency adjustment submodule is used to adjust the test frequency of the swept frequency impedance test and the single frequency impedance test.

6. The device according to claim 5, characterized in that The test frequency adjustment range of the adjustment submodule is 100kHz to 1Hz, and the adjustment step is 0.1Hz.

7. The device according to claim 1, characterized in that The signal processing and feedback module is further configured to analyze the status information of the battery to be tested according to the battery capacity of the battery to be tested.

8. The device according to claim 3, characterized in that The battery to be tested includes a lithium-ion battery; The signal collection module is configured to calculate an impedance value sequence of the battery under test during a preset period of time based on the current-carrying impedance test result of the battery under test during a preset period of time obtained from the testing module; a signal processing and feedback module, configured to calculate a capacitance value sequence of the battery to be tested in a preset time period based on the impedance value sequence in the preset time period obtained from the signal collection module; The signal processing and feedback module is further configured to determine lithium deposition status information of the battery to be tested based on a capacitance value sequence of the battery to be tested in a preset time period.

9. The device according to claim 8, characterized in that The device further includes a bias voltage / bias current module for stopping charging and discharging the battery under test in response to target lithium deposition state information sent by the signal processing and feedback module, wherein the target lithium deposition state information is used to indicate that lithium deposition occurs in the battery under test.

10. The device according to claim 1, characterized in that The device further comprises: The electromagnetic shielding module is used to shield the influence of electromagnetic induction on the test module.

11. The device according to claim 1, characterized in that The test module is further used to perform impedance testing on multiple calibration batteries to obtain impedance test results of each calibration battery; The signal collection module is further configured to calculate the impedance value of each calibration battery according to the impedance test result of each calibration battery obtained from the test module; The signal processing and feedback module is also used to calculate the capacitance value of each calibration battery based on the impedance value of each calibration battery obtained from the signal collection module; and determine the corresponding relationship between the capacitance value and the battery capacity based on the predetermined battery capacity of each calibration battery and the capacitance value of each calibration battery.

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