Battery detection method and device, battery management system and medium

Abstract

The present application relates to the technical field of battery detection, and discloses a battery detection method, a battery detection device, a battery management system and a medium, a three-electrode sample battery is obtained, and a lithium precipitation boundary of the three-electrode sample battery at different temperatures is obtained through testing; based on a target test temperature and a target state of charge, a charge-discharge test is performed on a target battery, a target impedance of the target battery at the target state of charge is obtained, and each impedance of the target battery at other temperatures and states is inferred, and the heat generated by the target battery at different charge-discharge states is further calculated; based on the heat, a target temperature value corresponding to different charge-discharge states is calculated, so as to predict the actual temperature of the target battery; in combination with the lithium precipitation boundary of the three-electrode sample battery and the actual temperature, the lithium precipitation boundary of the target battery is inferred; the lithium precipitation corresponding to the actual temperature rise of the target battery is predicted, so that the lithium precipitation misjudgment caused by temperature evaluation deviation is avoided, and the problem of inaccurate lithium precipitation boundary determination of the battery under different working conditions is solved.

Description

Technical Field

[0001] This invention relates to the field of battery testing technology, specifically to battery testing methods, devices, battery management systems, and media. Background Technology

[0002] With the rapid development of the new energy industry, new energy vehicles and energy storage systems are constantly raising the requirements for battery system energy density, fast charging performance, and thermal management design. The temperature change characteristics of batteries during charging and discharging directly affect the accurate judgment of lithium plating boundaries.

[0003] However, the lithium plating boundary analysis in related technologies relies on test data of pouch cells, and the lithium plating boundary is usually obtained under constant temperature or fixed temperature change conditions. When the actual operating temperature of the battery changes dynamically, it is difficult to effectively describe the influence mechanism of temperature change on lithium plating behavior, resulting in a serious deviation between the lithium plating boundary judgment result and the actual operating conditions, leading to inaccurate lithium plating boundary judgment under different operating conditions. Summary of the Invention

[0004] This invention provides a battery testing method, device, battery management system, and medium to solve the problem of inaccurate determination of lithium plating boundaries under different operating conditions.

[0005] In a first aspect, the present invention provides a battery detection method, the method comprising: Three-electrode sample batteries were obtained, and charge-discharge tests were performed on the three-electrode sample batteries to obtain the lithium plating boundary of the three-electrode sample batteries at each preset temperature. Based on the target test temperature and target state of charge, charge and discharge tests are performed on the target battery to obtain the target impedance of the target battery under the target state of charge, and the impedances of the target battery under other target temperatures and other charge and discharge states are deduced. Based on the preset current and the impedances corresponding to different charge and discharge states, the heat generated by the target battery in different charge and discharge states is calculated. Based on the heat generated by the target battery in different charge and discharge states, the target temperature value corresponding to the target battery in different charge and discharge states is calculated. Based on the target temperature value and the current ambient temperature, the actual temperature of the target battery is predicted. Based on the lithium plating boundary of the three-electrode sample battery and the actual temperature of the target battery, the lithium plating boundary of the target battery at the actual temperature is inferred.

[0006] This invention combines the lithium plating boundary data of a three-electrode sample battery with the actual temperature of the target battery to achieve a precise mapping of lithium plating from a static preset temperature to the actual temperature under dynamic changes. On the one hand, it can deduce impedance changes under full temperature and full charge conditions using only a small amount of measured impedance data, significantly reducing the amount of calibration experiments and testing costs. On the other hand, it predicts the actual temperature rise by coupling heat generation and environmental heat dissipation in real time, so that the reasoning of the lithium plating boundary no longer depends on a fixed ambient chamber temperature, but combines the actual thermal state of the battery. This enables the prediction of lithium plating under the actual temperature rise of the target battery, avoiding misjudgment of lithium plating caused by temperature assessment deviation, and solving the problem of inaccurate determination of lithium plating boundary under different operating conditions.

[0007] In one optional implementation, a three-electrode sample battery is obtained, and charge-discharge tests are performed on the three-electrode sample battery to obtain the lithium plating boundary of the three-electrode sample battery at each preset temperature, including: Several sample batteries are obtained where the difference between the battery capacity and the preset capacity is less than a preset capacity threshold, and the difference between the battery internal resistance and the preset internal resistance is less than a preset internal resistance threshold. Reference electrodes are configured for several sample batteries to obtain several three-electrode sample batteries. Several three-electrode sample batteries were placed in a preset temperature test chamber, and the temperature inside the preset temperature test chamber was adjusted to the target temperature. The sample batteries were then left to stand. During the resting process of several three-electrode sample cells, the open circuit potential of the reference electrode to the negative electrode of each three-electrode sample cell was monitored. After monitoring that the open circuit potential was stable, charge and discharge tests were conducted on the three-electrode sample battery at different preset temperatures and different charging rates to obtain the lithium plating boundary corresponding to different charging rates at each preset temperature.

[0008] This invention effectively eliminates individual differences between sample batteries through rigorous screening of capacity and internal resistance consistency, ensuring the representativeness and repeatability of subsequent lithium plating boundary data. By configuring reference electrodes for the samples and combining static and open-circuit potential monitoring, it ensures that the electrodes are in a stable thermodynamic equilibrium state before each test, avoiding interference from initial state fluctuations on the determination of lithium plating time, thereby significantly improving experimental accuracy. At the same time, the systematic coverage of multiple preset temperature and multiple charge rate combination tests constructs a lithium plating boundary covering all operating conditions, providing high-resolution and high-reliability benchmark data for real-time temperature inference of subsequent target batteries, and realizing the accuracy of lithium plating boundary detection.

[0009] In one optional implementation, charge-discharge tests are performed on the three-electrode sample battery at different preset temperatures and different charge rates to obtain the lithium plating boundaries of the three-electrode sample battery at each preset temperature and different charge rates, including: Extract the capacity corresponding to the negative electrode potential at different charging rates and different preset temperatures during the charging process of the three-electrode sample battery; Based on the capacity corresponding to the negative electrode potential at different charging rates and at different preset temperatures, and the initial capacity of the three-electrode battery, the state of charge at different charging rates and at different preset temperatures is determined. Construct the first relationship curve between the state of charge and the negative electrode potential at different charging rates under different temperatures; Determine the preset negative electrode lithium plating potential, and obtain the coordinates of each charge state where the preset negative electrode lithium plating potential intersects with the first relationship curve; Each state of charge coordinate is mapped to a second relationship curve between the state of charge and the charging rate of the three-electrode battery at different temperatures. Based on the second relationship curve, the critical points of the state of charge under different temperatures and charging rates are obtained, and the lithium deposition boundary of the three-electrode sample battery is determined based on each critical point of the state of charge.

[0010] This invention extracts data on the change of negative electrode potential with capacity during charging and combines it with the initial capacity to accurately calculate the state of charge (SOC). This transforms complex electrochemical signals into quantifiable engineering parameters, constructs multidimensional relationship curves between SOC, negative electrode potential, and charging rate at different temperatures, and uses a preset lithium plating potential as a unified criterion for intersection point location. This effectively eliminates the subjective error of manually judging the lithium plating moment based on experience, standardizes the determination of the lithium plating boundary, and further maps the intersection coordinates to a two-dimensional relationship curve between SOC and charging rate, directly providing the critical SOC value under various operating conditions. This improves the accuracy and efficiency of lithium plating boundary calibration and provides reliable data for quickly retrieving corresponding boundary values ​​for target batteries at different actual temperatures.

[0011] In one optional implementation, based on the target test temperature and the target state of charge, a charge-discharge test is performed on the target battery to obtain the target impedance of the target battery under the target state of charge, and the impedances of the target battery under other multiple target temperatures and other multiple charge-discharge states are inferred, including: At room temperature, adjust the current charge / discharge state of the target battery to the target state of charge corresponding to the target test temperature; The target battery is left to stand at the target test temperature for a preset time; In response to the detection that the target battery's charge / discharge state has stabilized at the target state of charge after a preset time, a heat generation model is used to perform a charge / discharge test on the target battery to obtain the voltage difference of the target battery before and after charge / discharge. The target impedance of the target battery at the target state of charge is determined based on the ratio of voltage difference to fixed current. Based on multiple preset charge and discharge states, charge and discharge tests are performed on the target battery at a first target temperature and a second target temperature, respectively, to obtain the first target impedance of the target battery at multiple charge and discharge states at the first target temperature and the second target impedance of the target battery at multiple charge and discharge states at the second target temperature. Based on the first target temperature, the second target temperature, each first target impedance, and each second target impedance, the Arrhenius equation is constructed. Based on the Arrhenius equation, the impedances of the target battery at multiple target temperatures and multiple charge / discharge states are inferred, where the target impedance is greater at higher target temperatures.

[0012] This invention adjusts the battery to the charge / discharge state corresponding to the target temperature at room temperature, and allows it to stand for a preset time until the target battery's charge / discharge state stabilizes at the target state of charge. Then, a pulse charge / discharge test is performed using a fixed current. The target impedance in this state is calculated based on the ratio of the voltage difference before and after the test to the fixed current. By performing pulse tests on the target battery at different temperatures, the accuracy and repeatability of impedance detection can be improved, avoiding prediction errors caused by state fluctuations or current changes, thereby improving the accuracy of battery temperature prediction results. By selecting at least two target temperatures and testing multiple charge / discharge states at the two target temperatures respectively, the corresponding first and second target impedances are obtained. Based on this, the Arrhenius equation is constructed, and the impedance at other temperatures and charge / discharge states is then calculated using this equation. The temperature and impedance are directly linearly positively correlated. This equation effectively deduces the impedance corresponding to other temperatures, reducing the amount of experimentation while reflecting the trend of impedance changes with temperature.

[0013] In one optional implementation, based on a preset current and various impedances corresponding to different charge and discharge states, the heat generated by the target battery under different charge and discharge states is calculated, including: A preset heat generation equation is determined, which is used to characterize the relationship between the heat generated by the target battery at different times and under different charge and discharge thresholds and the impedance. Based on the preset current and the impedances corresponding to different charging and discharging states, the values ​​of the preset heat generation equations corresponding to the impedances corresponding to different charging and discharging states are calculated respectively. The value of the preset heat generation equation is determined as the heat generated by the target battery under different charge and discharge states.

[0014] This invention first determines a preset heat generation equation characterizing the relationship between heat and impedance, then combines a preset current and various impedances corresponding to different charge and discharge states to calculate the values ​​of each heat generation equation, and uses these values ​​as the heat generated by the target battery under different charge and discharge states. By using a unified heat generation equation and impedance parameters, the heat generated under multiple charge and discharge states can be calculated, improving the reliability and efficiency of heat calculation, thereby predicting the temperature change trend of the target battery based on heat changes.

[0015] In one optional implementation, based on the heat generated by the target battery in different charge and discharge states, a target temperature value corresponding to the target battery in different charge and discharge states is calculated. Based on the target temperature value and the current ambient temperature, the actual temperature of the target battery is predicted, including: A preset temperature calculation formula is determined, which is used to characterize the relationship between battery heat and battery temperature corresponding to different charge and discharge states. Obtain the specific heat capacity and mass of the target battery; Based on the heat, specific heat capacity and mass of the target battery under different charge and discharge states, the temperature values ​​corresponding to the target battery under different charge and discharge states are calculated using a preset temperature calculation formula. The target temperature value is determined by summing up the various temperature values. The actual temperature of the target battery is predicted based on the sum of the target temperature and the ambient temperature.

[0016] This invention determines a preset temperature calculation formula to characterize the relationship between battery heat and temperature, and obtains the specific heat capacity and mass of the target battery. Using this formula, it calculates the corresponding temperature values ​​based on the heat generated in different charge and discharge states, specific heat capacity, and mass. Then, it sums the temperature values ​​to obtain the target temperature value. Finally, it sums the target temperature value with the current ambient temperature to predict the actual temperature of the target battery. By combining specific heat capacity, mass, and the quantitative relationship between heat and temperature, it can convert heat generation into specific temperature changes. In addition, by combining the ambient temperature, it can predict the actual operating temperature.

[0017] In one optional implementation, based on the lithium plating boundary of the three-electrode sample battery and the actual temperature of the target battery, the lithium plating boundary of the target battery at the actual temperature is inferred, including: Based on the actual temperature of the target battery, the target battery is charged at different charging rates to obtain a third relationship curve between the actual temperature of the target battery and the charging time. The third relationship curve is used to characterize the amount of heat generation change of the target battery at different charging times. Calculate the charging capacity corresponding to different charging times of the target battery, determine the state of charge of the target battery based on the ratio of charging capacity to initial capacity, and obtain the fourth relationship curve between the actual temperature of the target battery and each state of charge. The fourth relationship curve is used to characterize the amount of heat generation change of the target battery corresponding to different states of charge. The actual temperature and state of charge of the target battery at each moment are obtained based on the third and fourth relationship curves. Based on the actual temperature and state of charge at each moment, the predicted charging rate at each moment is determined from the first relationship curve, and the target state of charge critical point is determined from the second relationship curve based on the actual temperature and predicted charging rate at each moment. Based on the target state of charge critical point, the lithium plating boundary corresponding to the actual temperature of the target battery at each moment is determined.

[0018] This invention collects real-time temperature change data of the target battery during actual charging, constructs a dynamic relationship curve between actual temperature, charging time, and state of charge, integrates the actual thermal changes and electrochemical state of the target battery, and then uses the actual temperature and state of charge at each moment as an index to match and predict the charging rate from the first relationship curve constructed based on the three-electrode sample battery. Then, using the predicted rate and actual temperature as coordinates, the corresponding target state of charge critical point is accurately located from the second relationship curve, thereby realizing dynamic actual operating condition calibration. It fully considers the combined effects of heat accumulation during actual battery operation and environmental heat, and significantly improves the real-time performance of lithium plating boundary determination.

[0019] In a second aspect, the present invention provides a battery detection device, the device comprising: The acquisition module is used to acquire three-electrode sample batteries and perform charge-discharge tests on the three-electrode sample batteries to obtain the lithium plating boundary of the three-electrode sample batteries at each preset temperature. The test module is used to perform charge and discharge tests on the target battery based on the target test temperature and the target state of charge, obtain the target impedance of the target battery under the target state of charge, and deduce the impedance of the target battery under multiple other target temperatures and multiple other charge and discharge states. The calculation module is used to calculate the heat generated by the target battery in different charging and discharging states based on the preset current and the various impedances corresponding to different charging and discharging states. The prediction module is used to calculate the target temperature value of the target battery in different charge and discharge states based on the heat generated by the target battery in different charge and discharge states, and predict the actual temperature of the target battery based on the target temperature value and the current ambient temperature. The inference module is used to infer the lithium deposition boundary of the target battery at the actual temperature based on the lithium deposition boundary of the three-electrode sample battery and the actual temperature of the target battery.

[0020] Thirdly, the present invention provides a battery management system, including a controller, the controller including a memory and a processor, the memory and the processor being communicatively connected to each other, the memory storing computer instructions, and the processor executing the computer instructions to perform the method described in the first aspect or any corresponding embodiment thereof.

[0021] Fourthly, the present invention provides a computer-readable storage medium storing computer instructions for causing a computer to perform the method described in the first aspect or any corresponding embodiment thereof. Attached Figure Description

[0022] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of an application scenario according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the first process of a battery detection method according to an embodiment of the present invention; Figure 3 This is a schematic diagram of a second process for a battery detection method according to an embodiment of the present invention; Figure 4 This is a schematic diagram of a three-electrode battery according to an embodiment of the present invention; Figure 5 This is a schematic diagram showing the relationship between the state of charge, charging rate, and total electrical potential according to an embodiment of the present invention. Figure 6 This is a schematic diagram of the lithium plating boundary of a battery according to an embodiment of the present invention; Figure 7 This is a structural block diagram of a battery detection device according to an embodiment of the present invention; Figure 8 This is a schematic diagram of the controller of the battery management system according to an embodiment of the present invention. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] It is understood that before using the technical solutions disclosed in the various embodiments of the present invention, users should be informed of the types, scope of use, and usage scenarios of the personal information involved in the present invention and their authorization should be obtained in accordance with relevant laws and regulations through appropriate means.

[0026] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0027] like Figure 1 The battery management system shown includes a controller 101, which is used for charging and discharging control of the battery. The controller 101 is used to execute a battery detection method. The overall process of the controller 101 executing the battery detection method is detailed in the relevant description of the method embodiment below, and will not be repeated here.

[0028] Lithium-ion batteries face safety bottlenecks. As a core component of new energy vehicles and energy storage systems, the safety performance of lithium-ion batteries directly affects the reliability of the entire system. Lithium plating (the deposition of lithium metal on the negative electrode surface) is one of the main safety risks of lithium-ion batteries, leading to capacity decay, increased internal resistance, and even thermal runaway. Especially in prismatic batteries, the uneven temperature rise caused by the thermal conductivity of the metal casing, the non-uniformity of liquid-cooling and air-cooling distribution, and the non-uniformity of current density distribution makes localized lithium plating more likely.

[0029] In related technologies, charging capacity analysis has technical limitations. If the lithium plating boundary is only analyzed based on pouch cells, the lithium plating boundary obtained is under the condition of no temperature rise. However, in reality, the capacity, packaging structure, and thermal characteristics of prismatic batteries vary significantly. Prismatic batteries will experience temperature rise during the charging process, and directly applying data from pouch cells will lead to distortion in the judgment of safety boundaries.

[0030] With the rapid development of the new energy industry, new energy vehicles and energy storage systems are constantly raising the requirements for battery system energy density, fast charging performance, and thermal management design. Establishing an accurate lithium plating boundary model for prismatic batteries is beneficial for more accurately identifying the safety boundaries of the battery charging process and for providing a theoretical basis for the design of thermal management systems.

[0031] According to an embodiment of the present invention, a battery detection method embodiment is provided. It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. Furthermore, although a logical order is shown in the flowchart, in some cases, the steps shown or described may be executed in a different order than that shown here.

[0032] This embodiment provides a battery detection method, which can be used in the controller of the aforementioned battery management system. Figure 2 This is a schematic flowchart of a first method for battery detection according to an embodiment of the present invention, as shown below. Figure 2 As shown, the process includes the following steps: Step S201: Obtain a three-electrode sample battery and perform charge-discharge tests on the three-electrode sample battery to obtain the lithium plating boundary of the three-electrode sample battery at each preset temperature.

[0033] It should be noted that the three-electrode sample battery, in addition to the conventional positive and negative electrodes, incorporates a reference electrode. This reference electrode can monitor the negative electrode potential in real time, enabling precise determination of the lithium plating time. Conventional two-electrode batteries measure the overall voltage and cannot assess the negative electrode alone; therefore, a three-electrode sample battery is used in this embodiment.

[0034] Among them, charging test refers to a standardized experiment that charges and discharges the battery according to a set current, which is used to simulate the actual working state of the battery and record its performance data.

[0035] The preset temperature can be a specific temperature point set before the experiment, such as 25℃ or 45℃, to analyze the effect of temperature on the battery's charging acceptance capability and lithium plating tendency.

[0036] The lithium plating boundary refers to the critical condition at which metallic lithium begins to deposit on the surface of the negative electrode during battery charging. Exceeding this boundary will damage the battery, while falling below it will make it relatively safe.

[0037] Step S202: Based on the target test temperature and the target state of charge, perform charge and discharge tests on the target battery to obtain the target impedance of the target battery under the target state of charge, and deduce the impedance of the target battery under other target temperatures and other charge and discharge states.

[0038] It should be noted that when conducting charge and discharge tests on the target battery, the target test temperature can be multiple different temperature values, and the target state of charge can also be multiple at each temperature.

[0039] The target impedance can be the total resistance exhibited by the battery to changing current.

[0040] It should be noted that the other target temperatures inferred are different from the test temperature. This means that the impedances at these other temperatures can be inferred by testing the target battery at different temperatures. The state of charge / discharge (SOC) is used in this context.

[0041] Step S203: Based on the preset current and the impedances corresponding to different charge and discharge states, calculate the heat generated by the target battery in different charge and discharge states.

[0042] It should be noted that the current generates Joule heat when flowing through the ohmic resistor, polarization heat when flowing through the polarization resistor, and the heat generation of the battery also includes the impedance of entropy change. After testing the heat generation model, the response speed of each impedance is relatively uniform, which solves the problem of low accuracy of the calculated battery heat generation results caused by the different response of ohmic impedance, polarization impedance and entropy change impedance.

[0043] Step S204: Based on the heat generated by the target battery in different charge and discharge states, calculate the target temperature value corresponding to the target battery in different charge and discharge states, and predict the actual temperature of the target battery based on the target temperature value and the current ambient temperature.

[0044] It should be noted that the target temperature value of the target battery in different charge and discharge states is further deduced from the heat generated. Thus, the actual temperature of the target battery is predicted by different temperature values ​​and the current ambient temperature, where the current ambient temperature is the temperature of the environment in which the battery is located.

[0045] Specifically, the temperature change trend of the target battery can be determined by predicting the actual temperature of the target battery. For example, the rising temperature trend of the target battery can be predicted.

[0046] Step S205: Based on the lithium plating boundary of the three-electrode sample battery and the actual temperature of the target battery, infer the lithium plating boundary of the target battery at the actual temperature.

[0047] It should be noted that the target battery is a battery to be tested that is different from the three-electrode sample battery mentioned above. For example, the target battery can be a battery with two-electrode cells.

[0048] The battery detection method provided in this embodiment combines the lithium plating boundary data of the three-electrode sample battery with the actual temperature of the target battery to achieve accurate mapping of lithium plating from a static preset temperature to the actual temperature of dynamic changes. On the one hand, it can deduce the impedance change under full temperature and full charge state using a small amount of measured impedance data, which greatly reduces the amount of calibration experiments and testing costs. On the other hand, it predicts the actual temperature rise by coupling heat generation and environmental heat dissipation in real time, so that the reasoning of the lithium plating boundary no longer depends on the fixed ambient chamber temperature, but closely follows the actual thermal state of the battery. This enables the prediction of lithium plating corresponding to the actual temperature rise of the target battery, avoids the misjudgment of lithium plating caused by temperature assessment deviation, and solves the problem of inaccurate determination of lithium plating boundary under different operating conditions.

[0049] This embodiment provides a battery detection method, which can be used in the controller of the aforementioned battery management system. Figure 3 This is a schematic diagram of a second process for a battery detection method according to an embodiment of the present invention, as shown below. Figure 3 As shown, the process includes the following steps: Step S301: Obtain a three-electrode sample battery and perform charge-discharge tests on the three-electrode sample battery to obtain the lithium plating boundary of the three-electrode sample battery at each preset temperature.

[0050] Specifically, step S301 includes: Step S3011: Obtain several sample batteries whose battery capacity is less than the preset capacity threshold and whose battery internal resistance is less than the preset internal resistance threshold, and configure reference electrodes for several sample batteries to obtain several three-electrode sample batteries.

[0051] For example, positive electrode, negative electrode and separator are stacked to form a small soft pack battery. The number of stacked layers is less than 6. The electrode length is less than or equal to any value between 110mm and 130mm. For example, the electrode length is less than or equal to 120mm. The width is less than or equal to any value between 60mm and 80mm. For example, the width is less than or equal to 70mm.

[0052] After the battery cells are stacked, a reference potential is implanted in the middle of the cells, and a third reference electrode is drawn out. The third reference electrode requires a stable voltage. The reference electrode is activated to obtain a stable reference potential.

[0053] Specifically, the first capacity threshold can be any value between 3% and 10%, with an example first capacity threshold of 5%.

[0054] In this embodiment, the number of sample batteries is at least 3, and the corresponding number of three-electrode sample batteries is at least 3.

[0055] Step S3012: Place several three-electrode sample batteries in a preset temperature test chamber, adjust the temperature inside the preset temperature test chamber to the target temperature, and allow the several three-electrode sample batteries to stand for a period of time.

[0056] For example, the pouch cell with three electrodes that has completed initial calibration is placed in a high and low temperature test chamber, and the temperature inside the chamber is adjusted to the target test temperature T. The cell is then left to stand at this target test temperature for at least 3 hours to ensure that the internal and external temperatures of the cell are uniform and reach thermal equilibrium.

[0057] Step S3013: During the resting process of several three-electrode sample cells, monitor the open circuit potential of the reference electrode to the negative electrode of each three-electrode sample cell.

[0058] For example, an electrochemical workstation is used for monitoring. During the resting process, the open circuit potential of the reference electrode relative to the negative electrode is monitored simultaneously. Subsequent charge-discharge tests can only begin after the potential is confirmed to be stable and without drift.

[0059] In step S3014, after monitoring that the open circuit potential is stable, charge and discharge tests are performed on the three-electrode sample battery at different preset temperatures and different charging rates to obtain the lithium plating boundary corresponding to different charging rates at each preset temperature for the three-electrode sample battery.

[0060] Specifically, the battery is connected using a three-electrode configuration. Multiple charge and discharge rates are applied, with simultaneous voltage monitoring at the positive, negative, and reference electrodes to obtain the full battery voltage, positive reference voltage, and negative reference voltage. The change in negative electrode potential with capacity during charging is extracted, where capacity / initial capacity is represented by the State of Charge (SOC), resulting in a SOC-negative reference potential curve. The SOC corresponding to any value within a ±10mV range of the negative reference is then extracted for each charge rate.

[0061] In this embodiment, the SOC corresponding to a negative parameter of 0mV at each rate is extracted to obtain the SOC-rate curve, which is the lithium plating boundary curve of the pouch battery. Note that after charging at each rate at a certain temperature, it is necessary to return to room temperature for discharge.

[0062] The battery testing method provided in this embodiment effectively eliminates individual differences between sample batteries through strict screening of capacity and internal resistance consistency, ensuring the representativeness and repeatability of subsequent lithium plating boundary data. By configuring reference electrodes for the samples and combining static and open-circuit potential monitoring, it ensures that the electrodes are in a stable thermodynamic equilibrium state before each test, avoiding interference from initial state fluctuations on the determination of lithium plating time, thereby significantly improving experimental accuracy. At the same time, the systematic coverage of multiple preset temperature and multiple charging rate combination tests constructs a lithium plating boundary covering all operating conditions, providing high-resolution and high-reliability benchmark data for subsequent real-time temperature inference of target batteries, and realizing the accuracy of lithium plating boundary detection.

[0063] Specifically, step S3014 includes: Step a1: Extract the capacity corresponding to the negative electrode potential at different charging rates and different preset temperatures during the charging process of the three-electrode sample battery; Here, the capacity refers to the charging capacity. Different charging rates can be 0.5C, 1.0C, 1.5C, 0.8C, 1.2C, etc.; different preset temperatures can be 15℃, 25℃, 35℃, etc.

[0064] Step a2: Based on the capacity corresponding to the negative electrode potential at different charging rates and at different preset temperatures and the initial capacity of the three-electrode battery, determine the state of charge at different charging rates and at different preset temperatures. The state of charge (SOC) of the battery refers to the state of charge (COC) of the battery.

[0065] Step a3: Construct the first relationship curve between the state of charge and the negative electrode potential at different charging rates under different temperatures; The first relationship curve characterizes the variation of the negative electrode potential with the state of charge at different charging rates under a given temperature. The horizontal axis of the first relationship curve represents the state of charge, and the vertical axis represents the negative electrode potential. At the same charging rate, the negative electrode potential dynamically decreases as the state of charge increases.

[0066] Step a4: Determine the preset negative electrode lithium plating potential and obtain the coordinates of each charge state where the preset negative electrode lithium plating potential intersects with the first relationship curve; The preset negative electrode lithium plating potential is the negative parameter 0mV determined in the above steps. The negative parameter 0mV corresponds to a horizontal cutting line in the first relationship curve.

[0067] Step a5: Map each state of charge coordinate to a second relationship curve between the state of charge and the charging rate of the three-electrode battery at different temperatures; Specifically, each charge state coordinate refers to the x-coordinate of the intersection point between each rate curve and the corresponding horizontal cutting line in the first relationship curve where the negative parameter is 0mV. The second relationship curve is formed by connecting multiple intersection point x-coordinates.

[0068] The second relationship curve characterizes the direct correlation between the critical state of charge (SOC) that can be achieved at a certain temperature to avoid lithium plating and the charging rate. The horizontal axis of the second relationship curve represents the critical state of charge, and the vertical axis represents the charging rate. Different preset temperatures are represented by different individual curves. The two endpoints of this second relationship curve divide the safe charging range and the critical point of lithium plating boundary.

[0069] Step a6: Based on the second relationship curve, obtain the critical points of state of charge at different temperatures and charging rates, and determine the lithium plating boundary of the three-electrode sample battery based on each critical point of state of charge.

[0070] Specifically, using the steps described above, the critical points of the state of charge (SOC) at different temperatures and charging rates are obtained. Each SOC critical point is determined by the x-coordinate of the intersection point of the rate curve and the horizontal cutting line corresponding to the negative parameter of 0mV in the first relationship curve. This determines the lithium deposition boundaries of the three-electrode sample battery at different temperatures and charging rates.

[0071] The battery detection method provided in this embodiment extracts data on the change of negative electrode potential with capacity during charging and accurately calculates the state of charge (SOC) based on the initial capacity. This transforms complex electrochemical signals into quantifiable engineering parameters, constructs multidimensional relationship curves between SOC, negative electrode potential, and charging rate at different temperatures, and uses a preset lithium plating potential as a unified criterion for intersection point location. This effectively eliminates the subjective error of manually judging the lithium plating moment based on experience, standardizes the determination of the lithium plating boundary, and further maps the intersection coordinates to a two-dimensional relationship curve between SOC and charging rate, directly providing the critical SOC value under various operating conditions. This improves the accuracy and efficiency of lithium plating boundary calibration and provides reliable data for quickly retrieving corresponding boundary values ​​for target batteries at different actual temperatures.

[0072] Step S302: Based on the target test temperature and the target state of charge, perform charge and discharge tests on the target battery to obtain the target impedance of the target battery under the target state of charge, and deduce the impedance of the target battery under other target temperatures and other charge and discharge states.

[0073] Specifically, step S302 includes: Step b1: At room temperature, adjust the current charge / discharge state of the target battery to the target state of charge corresponding to the target test temperature; For example, adjusting the battery charge and discharge to a fixed SOC at room temperature.

[0074] For example, the target test temperature can be 25℃ and 40℃, 45℃, or other temperature points between -20℃ and 55℃.

[0075] Step b2: Place the target battery at the target test temperature for a preset time. The test involves allowing the battery to stand for a preset time until the target state of charge of the battery stabilizes within the preset error range of the target state of charge. Different test temperatures correspond to different desired states, which are the target state of charge. For example, when the target state of charge is 30%, the preset error range is ±0.5% of 30%, which is between 29.5% and 30.5%.

[0076] For example, the preset resting time can be 1 hour or 2 hours.

[0077] Step b3: In response to the detection that the charge / discharge state of the target battery has stabilized at the target state of charge after a preset time, the target battery is charged and discharged using a heat generation model to obtain the voltage difference of the target battery before and after charging and discharging. In this process, the battery is left to stand at a certain temperature for an extended period until its state stabilizes. Then, a pulse charge-discharge test is performed on the battery using a fixed current to obtain the voltage difference before and after charging.

[0078] The target test temperature includes at least a first target temperature and a second target temperature, wherein the first target temperature is lower than the second target temperature.

[0079] Specifically, step b3 includes: Step b01: At the first target temperature, perform a pulse charge-discharge test on the target battery based on a fixed current to obtain the first voltage difference of the target battery before and after charge-discharge at the first target temperature.

[0080] It should be noted that the pulse charge-discharge test involves a short period of power-on and then power-off. The voltage before the pulse charge-discharge begins and the voltage after the pulse charge-discharge ends are recorded. The first voltage difference is obtained based on the difference between the two. This first voltage difference reflects the DC internal resistance and polarization effect of the battery at the first target temperature, which is helpful for evaluating the low-temperature characteristics of the battery.

[0081] Step b02: At the second target temperature, perform a pulse charge-discharge test on the target battery based on a fixed current to obtain the second voltage difference of the target battery before and after charge-discharge at the second target temperature.

[0082] It should be noted that the voltage before the start of pulse charging and discharging and the voltage after the end of pulse charging and discharging are recorded. The difference between the two is used to obtain the second voltage difference, which reflects the DC internal resistance and polarization effect of the battery at the second target temperature. This is helpful for evaluating the high-temperature characteristics of the battery.

[0083] Specifically, the first target test impedance and the second target test impedance of the target battery at the target state of charge are determined based on the ratio of the first voltage difference to the fixed current and the ratio of the second voltage difference to the fixed current, respectively.

[0084] By comparing the voltage difference at different temperatures, the influence of temperature on battery polarization or internal resistance can be determined. This is beneficial for evaluating the differences in charge and discharge performance of batteries at low and high temperatures, and provides a basis for subsequent inference of impedance at other temperatures. Using pulse testing with a fixed current can improve the comparability of the results.

[0085] Step b4: Based on the ratio of voltage difference to fixed current, determine the target impedance corresponding to the target battery in the target state of charge. Specifically, the battery DCR (target impedance) at the target test temperature and SOC (target state of charge) is obtained by the ratio of the voltage difference to the fixed current. That is, to test the impedance at different SOCs, the battery is first adjusted to room temperature and then charged and discharged at room temperature until it is adjusted to a fixed SOC (state of charge and discharge). The target impedance at that temperature is then obtained by dividing the voltage difference by the current.

[0086] Step b5: Based on multiple preset charge and discharge states, charge and discharge tests are performed on the target battery at the first target temperature and the second target temperature respectively, to obtain the first target impedance of the target battery at the first target temperature and the second target impedance of the target battery at the second target temperature. Among them, at least a first target temperature and a second target temperature are determined, wherein the first target temperature is less than the second target temperature.

[0087] For example, the first target temperature is room temperature, such as 25°C, and the second target temperature is high temperature, such as 45°C. In optional embodiments of this example, the target temperatures can be determined to be different.

[0088] The various charge / discharge states can be 0%, 10%, 50%, 90%, and 100%. Charge / discharge refers to charging or discharging. For example, discharging at a constant current at 50% SOC is a preset charge / discharge state. Testing at different temperatures allows analysis of the effect of temperature on battery impedance.

[0089] This test establishes a three-dimensional mapping relationship between impedance and temperature, SOC, and charge / discharge state. When the battery management system needs to predict temperature rise, it can look up the corresponding impedance based on the current temperature and SOC, and then calculate the heat generation by combining it with the current, thereby predicting the temperature rise.

[0090] Step b6: Based on the first target temperature, the second target temperature, each first target impedance, and each second target impedance, construct the Arrhenius equation; For example, the impedance R was tested at different SOCs (State of Charge) of 25°C and 45°C, and the Arrhenius equation for impedance and temperature was constructed as follows:

[0091] Taking the logarithm of both sides of the equation, LnRi ~ 1 / T shows a linear correlation, yielding the slope and intercept of the linear equation. The impedance at other temperatures can then be calculated based on this linear relationship.

[0092] Step b7: Based on the Arrhenius equation, infer the impedance of the target battery at multiple target temperatures and multiple charge / discharge states, where the target impedance is greater at higher target temperatures.

[0093] Among them, temperature and impedance are linearly positively correlated.

[0094] The battery testing method provided in this embodiment adjusts the battery to the charge / discharge state corresponding to the target temperature at room temperature, and allows it to stand for a preset time until the target battery's charge / discharge state stabilizes at the target state of charge. Then, a pulse charge / discharge test is performed using a fixed current. The target impedance under this state is calculated based on the ratio of the voltage difference before and after the test to the fixed current. By performing pulse tests on the target battery at different temperatures, the accuracy and repeatability of impedance detection can be improved, avoiding prediction errors caused by state fluctuations or current changes, thereby improving the accuracy of battery temperature prediction results. By selecting at least two target temperatures and testing multiple charge / discharge states at the two target temperatures respectively, the corresponding first target impedance and second target impedance are obtained. Based on this, the Arrhenius equation is constructed, and the impedance under other temperatures and charge / discharge states is then calculated using this equation. The temperature and impedance are directly linearly positively correlated. The impedance corresponding to other temperatures can be effectively deduced through this equation, reducing the amount of experimentation while reflecting the trend of impedance change with temperature.

[0095] Step S303: Based on the preset current and the impedances corresponding to different charge and discharge states, calculate the heat generated by the target battery under different charge and discharge states.

[0096] Specifically, step S303 includes: Step c1: Determine the preset heat generation equation. The heat generation equation is used to characterize the relationship between the heat generated by the target battery at different times and under different charge and discharge thresholds and the impedance. Specifically, the heat generation equation is pre-set as follows:

[0097] Where P represents the heat generation power; I represents the charging and discharging current; R represents the battery DCR (battery impedance); and t represents the charging and discharging time.

[0098] This formula is used to calculate the heat generation power at each moment. I can be used for both direct charging and stepped charging.

[0099] Step c2: Based on the preset current and the impedances corresponding to different charge and discharge states, calculate the values ​​of the preset heat generation equations corresponding to the impedances corresponding to different charge and discharge states. The preset current can be either a DC charging current or a stepped charging current.

[0100] Step c3: Determine the value of the preset heat generation equation as the heat generated by the target battery under different charge and discharge states.

[0101] For example, the calculated heat generation power is determined as the heat generated by the target battery under different charge and discharge states.

[0102] The battery detection method provided in this embodiment first determines a preset heat generation equation that characterizes the relationship between heat and impedance. Then, it combines a preset current and various impedances corresponding to different charge and discharge states to calculate the values ​​of each heat generation equation. These values ​​are used as the heat generated by the target battery under different charge and discharge states. By using a unified heat generation equation and impedance parameters, the heat generated under various charge and discharge states can be calculated, improving the reliability and efficiency of heat calculation. Thus, the temperature change trend of the target battery can be predicted based on the heat change.

[0103] Step S304: Based on the heat generated by the target battery in different charge and discharge states, calculate the target temperature value corresponding to the target battery in different charge and discharge states, and predict the actual temperature of the target battery based on the target temperature value and the current ambient temperature.

[0104] Specifically, step S304 includes: Step d1: Determine the preset temperature calculation formula, which is used to characterize the relationship between battery heat and battery temperature corresponding to different charge and discharge states. For example, the temperature rise can be calculated using the following formula: Temperature rise calculation: ; Where Q represents the heat generated by the battery, calculated based on the heat generation model; C represents the specific heat capacity of the battery, obtained by testing with an adiabatic calorimeter (ARC); m represents the mass of the battery; and ΔT represents the temperature rise.

[0105] Step d2: Obtain the specific heat capacity and mass of the target battery; The specific heat capacity of the battery was obtained by testing with an adiabatic calorimeter (ARC).

[0106] Step d3: Based on the heat, specific heat capacity and mass generated by the target battery in different charge and discharge states, calculate the temperature values ​​corresponding to the target battery in different charge and discharge states using a preset temperature calculation formula. Specifically, .

[0107] Step d4: Sum the various temperature values ​​to determine the target temperature value; The target temperature value is the predicted temperature value of the target battery.

[0108] Step d5: Based on the sum of the target temperature value and the ambient temperature, predict the actual temperature of the target battery.

[0109] For example, the rising trend of the battery can be understood based on the continuously predicted actual temperature.

[0110] The battery detection method provided in this embodiment determines a preset temperature calculation formula to characterize the relationship between battery heat and temperature, and obtains the specific heat capacity and mass of the target battery. Using this formula, it calculates the corresponding temperature values ​​based on the heat generated in different charge and discharge states, specific heat capacity, and mass. Then, it sums the temperature values ​​to obtain the target temperature value. Finally, it sums the target temperature value with the current ambient temperature to predict the actual temperature of the target battery. By combining specific heat capacity, mass, and the quantitative relationship between heat and temperature, it can convert the generated heat into a specific temperature change. At the same time, by combining the ambient temperature, it can predict the actual operating temperature.

[0111] Step S305: Based on the lithium plating boundary of the three-electrode sample battery and the actual temperature of the target battery, infer the lithium plating boundary of the target battery at the actual temperature.

[0112] Specifically, step S305 includes: Step S3051: Based on the actual temperature of the target battery, charge the target battery at different charging rates to obtain the third relationship curve between the actual temperature of the target battery and the charging time. The third relationship curve is used to characterize the heat generation change of the target battery at different charging times. It should be noted that the battery temperature will rise significantly during actual charging due to its own heat generation.

[0113] The lithium plating boundary of the three-electrode sample battery was obtained by testing at a preset temperature. However, the target battery will experience different degrees of Joule heating and polarization heating when charged at different rates, resulting in the actual temperature of the target battery body being much higher than the ambient temperature. Therefore, it is necessary to obtain the actual temperature of the target battery as the main factor and then obtain the trend of the actual temperature change over time in order to obtain the amount of heat generation change of the target battery at different charging times.

[0114] Step S3052: Calculate the charging capacity corresponding to different charging times of the target battery, determine the state of charge of the target battery based on the ratio of charging capacity to initial capacity, and obtain the fourth relationship curve between the actual temperature of the target battery and each state of charge. The fourth relationship curve is used to characterize the amount of heat generation change of the target battery corresponding to different states of charge. Here, charging capacity is the amount of electricity charged, initial capacity is the total full charge capacity of the battery, and state of charge (SOC) is the percentage of remaining charge.

[0115] Step S3053: Based on the third and fourth relationship curves, obtain the actual temperature and state of charge of the target battery at each moment. It should be noted that, in order to obtain the lithium plating boundary of the target battery at each moment, time is used as a common variable, and the actual temperature and state of charge are synchronized.

[0116] Step S3054: Based on the actual temperature and state of charge at each moment, determine the predicted charging rate at each moment from the first relationship curve, and determine the target state of charge critical point from the second relationship curve based on the actual temperature and predicted charging rate at each moment. It should be noted that this step uses the actual temperature and actual state of charge at the current moment to reverse-engineer the predicted charging rate in this state from the first relationship curve.

[0117] Step S3055: Based on the target state of charge critical point, determine the lithium plating boundary corresponding to the actual temperature of the target battery at each moment.

[0118] It should be noted that the target state of charge critical point is the critical SOC value corresponding to the current charging rate at that temperature, which is found from the second relationship curve. That is, the state of charge when the negative electrode potential just drops to the lithium plating critical potential. Exceeding this value may cause lithium plating.

[0119] Among them, the lithium plating boundary is the maximum state of charge limit allowed for safe charging of the battery.

[0120] The battery detection method provided in this embodiment collects temperature change data of the target battery in real time during the actual charging process, constructs a dynamic relationship curve between actual temperature, charging time, and state of charge, integrates the actual thermal changes and electrochemical state of the target battery, and then uses the actual temperature and state of charge at each moment as an index to match and predict the charging rate from the first relationship curve constructed based on the three-electrode sample battery. Then, using the predicted rate and actual temperature as coordinates, the corresponding target state of charge critical point is accurately located from the second relationship curve, thereby realizing dynamic actual working condition calibration, fully considering the combined effects of heat accumulation during actual battery operation and environmental heat, and significantly improving the real-time performance of lithium plating boundary determination.

[0121] Combination Figures 4 to 6 This document describes an application example of the battery detection method described in this embodiment.

[0122] For example, Figure 4 To illustrate the fabrication of a pouch cell with three electrodes, the fabrication process is as follows: Step 1: Take the positive electrode, negative electrode, and separator and stack them to form a small pouch cell. The number of stacked layers should be less than 6. The electrode dimensions should be ≤120mm in length and ≤70mm in width.

[0123] After the battery cells are stacked, a reference electrode is inserted in the middle of the cell, and a third reference electrode is drawn out. The third reference electrode requires stable voltage.

[0124] The reference electrode is activated to obtain a stable reference potential.

[0125] Step 2: Perform charge-discharge tests on the three electrodes of the pouch cell to obtain the lithium deposition boundary of the pouch cell at different temperatures.

[0126] Initial performance benchmark calibration: Initial capacity calibration and internal resistance test. Select batteries whose capacity and internal resistance consistency meet the preset deviation threshold (deviation < 5%) as test samples. Use at least three parallel samples at each temperature point.

[0127] Temperature equilibration treatment: Place the initially calibrated pouch cell with three electrodes in a high and low temperature test chamber and adjust the chamber temperature to the first target test temperature T. Allow the cells to stand at this target temperature for at least 3 hours to ensure uniform internal and external temperatures and achieve thermal equilibrium.

[0128] Monitoring was performed using an electrochemical workstation. During the settling process, the open-circuit potential of the reference electrode relative to the negative electrode was monitored simultaneously. Subsequent charge-discharge tests could only begin after the potential was confirmed to be stable and without drift.

[0129] For example, Figure 5 The graphs show the relationship between state of charge and charging rate, and between state of charge and total electrical potential. The curve showing the relationship between state of charge and charging rate is the first relationship curve in the above method embodiment.

[0130] Lithium plating boundary curves at different temperatures were obtained by charging at different temperatures: the battery was connected in a three-electrode configuration, and the battery was charged and discharged at multiple rates while voltage monitoring was performed simultaneously on the positive, negative, and reference electrodes to obtain the full battery voltage, positive reference voltage, and negative reference voltage.

[0131] For example, Figure 6 This is a schematic diagram of the lithium plating boundary of the battery, i.e., the SOC-rate curve, which corresponds to the second relationship curve in the above method embodiment.

[0132] The change in negative electrode potential with capacity during charging is extracted, where capacity / initial capacity is represented by SOC, resulting in a SOC-negative parameter potential curve. The SOC corresponding to 0mV negative parameter at each rate is extracted, yielding an SOC-rate curve, which represents the lithium plating boundary curve for the pouch cell. Note that after charging at each rate at a certain temperature, the battery needs to be discharged at room temperature to obtain the lithium plating boundaries for the pouch cell at multiple temperatures.

[0133] Thermal simulation of prismatic batteries includes the following process: Cell impedance testing and calculation: Fabrication of prismatic batteries, in which the positive electrode is made of materials such as lithium iron phosphate and ternary lithium, and the negative electrode is made of materials such as graphite.

[0134] The battery with the square casing is subjected to a constant capacity test. After constant capacity, the State of Charge (SOC) is adjusted at room temperature based on the capacity. The impedance is then tested using an HPPC (Power-On-Cycle Test). The battery is left to stand at a certain temperature for an extended period until its state stabilizes. A pulse charge-discharge test is then performed on the battery using a fixed current to obtain the voltage difference. The ratio of the voltage difference to the fixed current yields the battery impedance at that temperature and SOC.

[0135] Impedances at different SOCs under typical high and normal temperatures were obtained. Impedances at other temperatures were derived using the Arrhenius equation. The specific derivation steps are as follows: Impedance R was measured at different SOCs at 25℃, 40℃, and 45℃. The Arrhenius equation for impedance and temperature, Ri = A*exp(-Ea / RT), was constructed. Taking the logarithm of both sides of the equation, LnRi ~ 1 / T showed a linear correlation, yielding the slope and intercept of the linear equation. Impedances at other temperatures (30℃, 35℃, 50℃) were calculated based on this linear relationship. Using existing data, the relationship between temperature and DCR was interpolated using the Arrhenius equation, and the relationship between SOC and DCR was interpolated using linear interpolation, resulting in a more detailed DCR table. Specific heat capacity test and calculation of battery cell: Specific heat capacity represents the amount of heat required to raise the temperature of a unit mass of material by 1°C. The calculation formula is C=Q / (m×ΔT), where: Q is the input heat (J), m is the mass of the battery cell (kg), and ΔT is the temperature change (°C).

[0136] The battery cell was placed in the adiabatic chamber of the accelerated calorimeter (ARC), ensuring environmental insulation to prevent heat loss. The cell mass (m) and initial temperature (Tinitial) were recorded. The cell was heated by applying a constant power (P) through an external heating system. The cell temperature was monitored in real time until the target temperature (Tfinal) was reached, and the heating time (t) was recorded. The specific heat capacity of the cell was calculated.

[0137] The external heating system uses an electric heating wire as the heat source, with a heating power selection range of 5-10W. The heat input Q is calculated as: Q = P * t. The sample heating mechanism involves arranging resistance heating wires around the sample chamber. The heating wires are heated by precisely controlling the current, and the heat is conducted to the tested battery cell through the chamber. The heating power can be adjusted in real time to maintain an adiabatic environment (the temperature difference between the sample and the environment approaches zero). Adiabatic control is achieved by the instrument dynamically adjusting the heating power through a feedback system, ensuring that the sample's own exothermic or endothermic processes are not affected by environmental heat exchange. When the battery cell reacts, the system synchronously increases the chamber temperature, achieving true "zero heat loss" conditions.

[0138] The specific heat capacity Cp of the battery cell is calculated using the formula Cp=Q / (m×△T).

[0139] Battery cell charging at different ambient temperatures, temperature simulation: During the charging and discharging process of the battery cell, the heat generated by the battery is Q = I²Rt. I is the charging and discharging current; R can be obtained from the table in step 1 based on the changes in temperature and SOC; the cumulative heat Q during the charging and discharging process can be obtained by integrating over time.

[0140] Meanwhile, Q = Cp × (m × ΔT), where Cp is the specific heat capacity of the cell and m is the mass of the cell, thus deriving the battery temperature rise. The battery temperature rise plus the ambient temperature equals the change in battery temperature during charging and discharging. Derivation of the lithium plating boundary in prismatic cells by coupling soft-pack lithium plating boundary with thermal simulation of prismatic cells: Based on the thermal simulation model, a charging strategy with a certain charging rate is input into the prismatic battery, and the temperature change of the prismatic battery over time during the charging process is derived through thermal simulation.

[0141] Using the ampere-hour integration method, the change of charging capacity over time is obtained. The ratio of charging capacity to initial capacity is taken as SOC, and the temperature change curve with SOC is obtained.

[0142] The lithium plating boundary was obtained from the soft-pack test at different temperatures. The SOC and rate capability at different temperatures are shown in Table 1 below: Table 1. Lithium Plating Boundary-SOC Table at Different Temperatures

[0143] Using a nonlinear interpolation method (such as cubic spline interpolation, Lagrange interpolation, or Newton interpolation), the lithium plating boundary under different SOCs of the pouch cell is further filled with temperature and rate interpolation to obtain an interpolation table. Utilizing a numerical model of the lithium plating boundary coupled with temperature, based on the temperature rise of the prismatic shell, the prismatic shell has a corresponding temperature and SOC at each moment. The maximum charging rate at this moment is obtained from the interpolation table, and the lithium plating boundary of the prismatic shell is derived.

[0144] The beneficial effects of the battery detection method in this embodiment are as follows: During the charging process of a prismatic battery, there is a temperature rise, and the local temperature at each point is non-uniform, making it difficult to obtain the true lithium plating boundary at each location on the prismatic battery. The lithium plating boundary obtained using a pouch battery, compared to the prismatic battery, does not experience a temperature rise, and its lithium plating boundary is more conservative. This patent proposes a method that combines the lithium plating boundary of a pouch battery with thermal simulation to derive a more realistic lithium plating boundary for prismatic batteries. This is beneficial for establishing an accurate lithium plating boundary model for prismatic batteries, providing support for thermal management in practical applications.

[0145] Currently, battery temperatures in the industry are mostly obtained through actual measurements using temperature sensing lines under various operating conditions, which is time-consuming and yields limited temperature data. This embodiment utilizes the Arrhenius equation to derive the temperature coefficient of thermal expansion (DCR) at different temperatures and states of charge (SOC), and leverages the DCR heat generation model to derive the battery temperature rise. This method is simple, fast, and can achieve temperature derivation across all temperatures and SOCs, saving time while providing more comprehensive coverage of operating conditions.

[0146] This embodiment also provides a battery detection device for implementing the above embodiments and preferred embodiments; details already described will not be repeated. As used below, the term "module" can refer to a combination of software and / or hardware that performs a predetermined function. Although the device described in the following embodiments is preferably implemented in software, hardware implementation, or a combination of software and hardware, is also possible and contemplated.

[0147] This embodiment provides a battery testing device, such as... Figure 7 As shown, it includes: The acquisition module 701 is used to acquire a three-electrode sample battery and perform charge-discharge tests on the three-electrode sample battery to obtain the lithium plating boundary of the three-electrode sample battery at each preset temperature. Test module 702 is used to perform charge and discharge tests on the target battery based on the target test temperature and the target state of charge, obtain the target impedance of the target battery under the target state of charge, and deduce the impedance of the target battery under other multiple target temperatures and other multiple charge and discharge states. The calculation module 703 is used to calculate the heat generated by the target battery in different charging and discharging states based on the preset current and the various impedances corresponding to different charging and discharging states. The prediction module 704 is used to calculate the target temperature value of the target battery in different charge and discharge states based on the heat generated by the target battery in different charge and discharge states, and predict the actual temperature of the target battery based on the target temperature value and the current ambient temperature. The inference module 705 is used to infer the lithium deposition boundary of the target battery at the actual temperature based on the lithium deposition boundary of the three-electrode sample battery and the actual temperature of the target battery.

[0148] In some alternative implementations, the acquisition module 701 includes: The acquisition unit is used to acquire a number of sample batteries whose battery capacity is less than a first capacity threshold and whose battery internal resistance is less than a second internal resistance threshold, and to configure a reference electrode for the number of sample batteries to obtain a number of three-electrode sample batteries.

[0149] The adjustment unit is used to place several three-electrode sample batteries in a preset temperature test chamber, adjust the temperature inside the preset temperature test chamber to the target temperature, and perform a static treatment on the several three-electrode sample batteries.

[0150] The monitoring unit is used to monitor the open-circuit potential of the reference electrode to the negative electrode of each three-electrode sample cell during the resting process.

[0151] The test unit is used to perform charge and discharge tests on the three-electrode sample battery at different preset temperatures and different charging rates after the open circuit potential is detected to be stable, so as to obtain the lithium plating boundary of the three-electrode sample battery at each preset temperature and different charging rates.

[0152] In some alternative implementations, the monitoring unit includes: The extraction subunit is used to extract the capacity corresponding to the negative electrode potential at different charging rates and different preset temperatures during the charging process of the three-electrode sample battery; The sub-unit is determined to determine the state of charge at different charging rates and preset temperatures based on the capacity corresponding to the negative electrode potential at different charging rates and at different preset temperatures and the initial capacity of the three-electrode battery. Construct sub-units to build the first relationship curves between the state of charge and different charging rates of the negative electrode potential at different temperatures; The coordinate determination sub-unit is used to determine the preset negative electrode lithium plating potential and obtain the coordinates of each charge state that intersects the preset negative electrode lithium plating potential and the first relationship curve. The first curve determines the sub-unit, which is used to map each state of charge coordinate to a second relationship curve between the state of charge and the charging rate of the three-electrode battery at different temperatures. The second curve determines the sub-unit, which is used to obtain the critical points of the state of charge at different temperatures and charging rates based on the second relationship curve, and to determine the lithium deposition boundary of the three-electrode sample battery based on each critical point of the state of charge.

[0153] In some alternative implementations, test module 702 includes: The room temperature test unit is used to adjust the current charge / discharge state of the target battery to the target state of charge corresponding to the target test temperature at room temperature. The settling unit is used to set the target battery at the target test temperature for a preset time. The heat generation test unit is used to respond to the detection that the charge / discharge state of the target battery has stabilized at the target state of charge after a preset time. It uses the heat generation model to perform charge / discharge tests on the target battery to obtain the voltage difference of the target battery before and after charge / discharge. Based on the ratio of the voltage difference to the fixed current, the target impedance corresponding to the target battery at the target state of charge is determined. Impedance calculation unit is used to perform charge and discharge tests on the target battery at a first target temperature and a second target temperature based on multiple preset charge and discharge states, respectively, to obtain the first target impedance of the target battery at multiple charge and discharge states at the first target temperature, and the second target impedance of the target battery at multiple charge and discharge states at the second target temperature. Construct equation units to build the Arrhenius equation based on the first target temperature, the second target temperature, each first target impedance, and each second target impedance; The inference impedance unit is used to infer the impedance of the target battery at multiple target temperatures and multiple charge / discharge states based on the Arrhenius equation, wherein the target impedance is greater at higher target temperatures.

[0154] In some alternative implementations, the computing module 703 includes: The heat prediction unit is used to determine the preset heat generation equation, which is used to characterize the relationship between the heat generated by the target battery at different times and under different charge and discharge thresholds and the impedance. The heat generation calculation unit is used to calculate the value of the preset heat generation equation corresponding to each impedance corresponding to different charging and discharging states, based on the preset current and each impedance corresponding to different charging and discharging states. The heat calculation unit is used to determine the value of the preset heat generation equation as the heat generated by the target battery under different charge and discharge states.

[0155] In some alternative implementations, the prediction module 704 includes: A temperature calculation unit is used to determine a preset temperature calculation formula, wherein the temperature calculation formula is used to characterize the relationship between battery heat and battery temperature corresponding to different charge and discharge states. A mass acquisition unit is used to acquire the specific heat capacity and mass of the target battery. The temperature calculation unit is used to calculate the temperature values ​​corresponding to the target battery in different charge and discharge states based on the heat, specific heat capacity and mass generated by the target battery in different charge and discharge states, using a preset temperature calculation formula. The target temperature calculation unit is used to accumulate various temperature values ​​to determine the target temperature value; The actual temperature prediction unit is used to predict the actual temperature of the target battery based on the sum of the target temperature value and the ambient temperature.

[0156] In some alternative implementations, the inference module 705 includes: The third curve determination unit is used to charge the target battery at different charging rates based on the actual temperature of the target battery, and obtain the third relationship curve between the actual temperature of the target battery and the charging time. The third relationship curve is used to characterize the amount of heat generation change of the target battery at different charging times. The fourth curve determination unit is used to calculate the charging capacity corresponding to different charging times of the target battery, determine the state of charge of the target battery based on the ratio of charging capacity to initial capacity, and obtain the fourth relationship curve between the actual temperature of the target battery and each state of charge. The fourth relationship curve is used to characterize the amount of heat generation change of the target battery corresponding to different states of charge. The temperature and state of charge determination unit is used to obtain the actual temperature and state of charge of the target battery at each moment based on the third relationship curve and the fourth relationship curve. The critical point determination unit is used to determine the predicted charging rate corresponding to each moment from the first relationship curve based on the actual temperature and state of charge at each moment, and to determine the target state of charge critical point from the second relationship curve based on the actual temperature and predicted charging rate at each moment. The lithium plating prediction unit is used to determine the lithium plating boundary corresponding to the actual temperature of the target battery at each moment, based on the target state of charge critical point.

[0157] The battery testing device provided in this embodiment of the invention can execute the battery testing method provided in any embodiment of the invention, and has the corresponding functional modules and beneficial effects for executing the method. Further functional descriptions of the various modules and units described above are the same as in the corresponding embodiments described above, and will not be repeated here.

[0158] Figure 8 This is a schematic diagram of the structure of a controller provided in an embodiment of the present invention.

[0159] The following is a detailed reference. Figure 8 The diagram illustrates a structural schematic suitable for implementing a controller in an embodiment of the present invention. The controller may include a processor (e.g., a central processing unit, graphics processing unit, etc.) 801, which can perform various appropriate actions and processes according to a program stored in read-only memory (ROM) 802 or a program loaded from memory 808 into random access memory (RAM) 803. RAM 803 also stores various programs and data required for controller operation. The processor 801, ROM 802, and RAM 803 are interconnected via bus 804. Input / output (I / O) interface 805 is also connected to bus 804.

[0160] Typically, the following devices can be connected to I / O interface 805: input devices 806 including, for example, a touchscreen, touchpad, keyboard, mouse, camera, microphone, accelerometer, gyroscope, etc.; output devices 807 including, for example, a liquid crystal display (LCD), speaker, vibrator, etc.; memory 808 including, for example, magnetic tape, hard disk, etc.; and communication devices 809. Communication device 809 allows the controller to communicate wirelessly or wiredly with other devices to exchange data. Although Figure 8A controller with various devices is shown, but it should be understood that it is not required to implement or have all of the devices shown, and may alternatively implement or have more or fewer devices.

[0161] In particular, according to embodiments of the present invention, the processes described above with reference to the flowcharts can be implemented as computer software programs. For example, embodiments of the present invention include a computer program product comprising a computer program carried on a non-transitory computer-readable medium, the computer program containing program code for performing the methods shown in the flowcharts. In such embodiments, the computer program can be downloaded and installed from a network via a communication device 809, or installed from a memory 808, or installed from a ROM 802. When the computer program is executed by the processor 801, it performs the functions defined in the battery detection method of the embodiments of the present invention.

[0162] Figure 8 The controller shown is merely an example and should not be construed as limiting the functionality and scope of use of the embodiments of the present invention.

[0163] This invention also provides a computer-readable storage medium. The methods described above according to embodiments of the invention can be implemented in hardware or firmware, or implemented as computer code that can be recorded on a storage medium, or implemented as computer code downloaded via a network and originally stored on a remote storage medium or a non-transitory machine-readable storage medium and then stored on a local storage medium. Thus, the methods described herein can be processed by software stored on a storage medium using a general-purpose computer, a dedicated processor, or programmable or dedicated hardware. The storage medium can be a magnetic disk, optical disk, read-only memory, random access memory, flash memory, hard disk, or solid-state drive, etc.; further, the storage medium can also include combinations of the above types of memory. It is understood that computers, processors, microprocessor controllers, or programmable hardware include storage components capable of storing or receiving software or computer code. When the software or computer code is accessed and executed by the computer, processor, or hardware, the battery detection method shown in the above embodiments is implemented.

[0164] A portion of this invention can be applied as a computer program product, such as computer program instructions, which, when executed by a computer, can invoke or provide the methods and / or technical solutions according to the invention through the operation of the computer. Those skilled in the art will understand that the forms in which computer program instructions exist in a computer-readable medium include, but are not limited to, source files, executable files, installation package files, etc. Correspondingly, the ways in which computer program instructions are executed by a computer include, but are not limited to: the computer directly executing the instructions, or the computer compiling the instructions and then executing the corresponding compiled program, or the computer reading and executing the instructions, or the computer reading and installing the instructions and then executing the corresponding installed program. Here, the computer-readable medium can be any available computer-readable storage medium or communication medium accessible to a computer.

[0165] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A battery testing method, characterized in that, The method includes: A three-electrode sample battery was obtained, and the three-electrode sample battery was charged and discharged to obtain the lithium plating boundary of the three-electrode sample battery at each preset temperature. Based on the target test temperature and the target state of charge, the target battery is charged and discharged to obtain the target impedance of the target battery under the target state of charge, and the impedance of the target battery under other target temperatures and other charge and discharge states is deduced. Based on the preset current and the various impedances corresponding to different charge and discharge states, the heat generated by the target battery in different charge and discharge states is calculated. Based on the heat generated by the target battery under different charge and discharge states, the target temperature value corresponding to the target battery under different charge and discharge states is calculated, and based on the target temperature value and the current ambient temperature, the actual temperature of the target battery is predicted. Based on the lithium plating boundary of the three-electrode sample battery and the actual temperature of the target battery, the lithium plating boundary of the target battery at the actual temperature is inferred.

2. The method according to claim 1, characterized in that, The process of obtaining a three-electrode sample battery and performing charge-discharge tests on the three-electrode sample battery to obtain the lithium plating boundary of the three-electrode sample battery at each preset temperature includes: Several sample batteries are obtained whose battery capacity is less than a preset capacity threshold and whose battery internal resistance is less than a preset internal resistance threshold. Reference electrodes are configured for the several sample batteries to obtain several three-electrode sample batteries. Several three-electrode sample batteries are placed in a preset temperature test chamber, the temperature inside the preset temperature test chamber is adjusted to the target temperature, and the several three-electrode sample batteries are left to stand. During the resting process of several three-electrode sample cells, the open-circuit potential of the reference electrode to the negative electrode of each three-electrode sample cell is monitored. After monitoring that the open circuit potential is stable, the three-electrode sample battery is charged and discharged at different preset temperatures and different charging rates to obtain the lithium plating boundary corresponding to different charging rates at each preset temperature.

3. The method according to claim 2, characterized in that, The process of conducting charge-discharge tests on the three-electrode sample battery at different preset temperatures and different charging rates to obtain the lithium plating boundaries of the three-electrode sample battery at each preset temperature and different charging rates includes: Extract the capacity corresponding to the negative electrode potential at different charging rates and different preset temperatures during the charging process of the three-electrode sample battery; Based on the capacity corresponding to the negative electrode potential at different charging rates and at different preset temperatures, and the initial capacity of the three-electrode battery, the state of charge at different charging rates and at different preset temperatures is determined. Construct the first relationship curve between the state of charge and the negative electrode potential at different charging rates under different temperatures; Determine the preset negative electrode lithium plating potential, and obtain the coordinates of each charge state that intersects the preset negative electrode lithium plating potential with the first relationship curve; The coordinates of each state of charge are mapped to a second relationship curve between the state of charge and the charging rate of the three-electrode battery at different temperatures. Based on the second relationship curve, the critical points of the state of charge under different temperatures and charging rates are obtained, and the lithium plating boundary of the three-electrode sample battery is determined based on each critical point of the state of charge.

4. The method according to claim 3, characterized in that, The process involves performing charge-discharge tests on the target battery based on the target test temperature and target state of charge to obtain the target impedance of the target battery under the target state of charge, and then inferring the impedances of the target battery under multiple other target temperatures and multiple other charge-discharge states, including: At room temperature, the current charge / discharge state of the target battery is adjusted to the target state of charge corresponding to the target test temperature; The target battery is left to stand at the target test temperature for a preset time; In response to the detection that the charge / discharge state of the target battery has stabilized at the target state of charge after the preset time, the target battery is charged and discharged using the heat generation model to obtain the voltage difference of the target battery before and after charging and discharging; based on the ratio of the voltage difference to the fixed current, the target impedance of the target battery corresponding to the target state of charge is determined. Based on multiple preset charge and discharge states, the target battery is subjected to charge and discharge tests at a first target temperature and a second target temperature, respectively, to obtain the first target impedance of the target battery at the first target temperature for multiple charge and discharge states and the second target impedance of the target battery at the second target temperature for multiple charge and discharge states, wherein the first target temperature is lower than the second target temperature. Based on the first target temperature, the second target temperature, the first target impedance, and the second target impedance, the Arrhenius equation is constructed. Based on the Arrhenius equation, the impedances of the target battery under various other target temperatures and various other charge and discharge states are inferred, wherein the target impedance is greater when the target temperature is higher.

5. The method according to claim 4, characterized in that, The calculation of the heat generated by the target battery under different charge and discharge states based on the preset current and the various impedances corresponding to different charge and discharge states includes: A preset heat generation equation is determined, which is used to characterize the relationship between the heat generated by the target battery at different times and under different charge and discharge thresholds and the impedance. Based on the preset current and the impedances corresponding to the different charging and discharging states, the values ​​of the preset heat generation equations corresponding to the impedances corresponding to the different charging and discharging states are calculated respectively. The value of the preset heat generation equation is determined as the heat generated by the target battery under different charge and discharge states.

6. The method according to claim 5, characterized in that, The step of calculating the target temperature value corresponding to the target battery in different charge and discharge states based on the heat generated by the target battery in different charge and discharge states, and predicting the actual temperature of the target battery based on the target temperature value and the current ambient temperature, includes: A preset temperature calculation formula is determined, wherein the temperature calculation formula is used to characterize the relationship between battery heat and battery temperature corresponding to different charge and discharge states; Obtain the specific heat capacity and mass of the target battery; Based on the heat generated by the target battery under different charge and discharge states, the specific heat capacity and the mass, the temperature values ​​corresponding to the target battery under different charge and discharge states are calculated using a preset temperature calculation formula. The target temperature value is determined by summing up the individual temperature values. The actual temperature of the target battery is predicted based on the sum of the target temperature value and the ambient temperature.

7. The method according to claim 1 or 6, characterized in that, The step of inferring the lithium plating boundary of the target battery at the actual temperature based on the lithium plating boundary of the three-electrode sample battery and the actual temperature of the target battery includes: Based on the actual temperature of the target battery, the target battery is charged at different charging rates to obtain a third relationship curve between the actual temperature of the target battery and the charging time. The third relationship curve is used to characterize the amount of heat generation change of the target battery at different charging times. Calculate the charging capacity corresponding to different charging times of the target battery, determine the state of charge of the target battery based on the ratio of charging capacity to initial capacity, and obtain a fourth relationship curve between the actual temperature of the target battery and each state of charge. The fourth relationship curve is used to characterize the amount of heat generation change of the target battery corresponding to different states of charge. Based on the third and fourth relationship curves, the actual temperature and state of charge of the target battery at each moment are obtained; Based on the actual temperature and state of charge at each moment, the predicted charging rate at each moment is determined from the first relationship curve, and the target state of charge critical point is determined from the second relationship curve based on the actual temperature and predicted charging rate at each moment. Based on the target state of charge critical point, the lithium plating boundary corresponding to the actual temperature of the target battery at each moment is determined.

8. A battery testing device, characterized in that, The device includes: The acquisition module is used to acquire a three-electrode sample battery and perform charge-discharge tests on the three-electrode sample battery to obtain the lithium plating boundary of the three-electrode sample battery at each preset temperature. The test module is used to perform charge and discharge tests on the target battery based on the target test temperature and the target state of charge, obtain the target impedance of the target battery under the target state of charge, and deduce the impedance of the target battery under other multiple target temperatures and other multiple charge and discharge states. The calculation module is used to calculate the heat generated by the target battery in different charging and discharging states based on the preset current and the various impedances corresponding to different charging and discharging states. The prediction module is used to calculate the target temperature value of the target battery in different charge and discharge states based on the heat generated by the target battery in different charge and discharge states, and to predict the actual temperature of the target battery based on the target temperature value and the current ambient temperature. The inference module is used to infer the lithium plating boundary of the target battery at the actual temperature based on the lithium plating boundary of the three-electrode sample battery and the actual temperature of the target battery.

9. A battery management system, characterized in that, Includes a controller, the controller comprising: A memory and a processor, the memory and the processor being communicatively connected to each other, the memory storing computer instructions, the processor executing the computer instructions to perform the method of any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer instructions for causing the computer to perform the method of any one of claims 1 to 7.

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