A method, device, equipment and storage medium for determining the capacity of a lithium battery

Abstract

The present invention discloses a method, device, equipment and storage medium for determining the capacity of a lithium battery. By extracting the test data of the battery capacity and voltage at the full operating temperature, establishing a database, and plotting the voltage-capacity curves at different temperatures, the influence of the dynamic temperature change is considered, making the calculation of the capacity state more accurate. At the same time, from the perspective of practical applications, the irreversible capacity loss during the charge and discharge cycle of the battery is considered, the relationship between the capacity retention rate and the number of cycles is explored, and it is combined with the relationship curves of voltage and energy at different temperatures to establish a database, so that the relationship curves of voltage and capacity at different temperatures for any number of cycles can be obtained. Due to the establishment of this curve graph and database, the capacity state is visualized, and the capacity state in any subsequent state can be quickly calculated, more conveniently, real-time and accurately predicting the capacity of the battery.

Description

Technical Field

[0001] The present invention relates to lithium battery technology, and particularly to a method, device, equipment and storage medium for determining the capacity of a lithium battery. Background Art

[0002] The advantages and disadvantages of battery technology seriously affect the development of new energy vehicles. Among them, the real-time calculation and analysis of the performance state of the batteries carried by new energy is particularly important. Battery capacity is one of the important performance indicators to measure battery performance. It represents the amount of electricity discharged by the battery under certain conditions, that is, the capacity of the battery, usually in ampere-hours (denoted as A·h, 1 A·h = 3600 C).

[0003] However, the battery capacity is greatly affected by temperature and the number of charge and discharge cycles. Therefore, it is particularly important to overcome these influencing factors to more accurately detect the capacity state of the battery. Summary of the Invention

[0004] The present invention provides a method, device, equipment and storage medium for determining the capacity of a lithium battery, so as to realize real-time and accurate prediction of the battery capacity according to the current state of the battery.

[0005] In a first aspect, the present invention provides a method for determining the capacity of a lithium battery, including:

[0006] Performing charge and discharge tests on a battery sample with a charge and discharge cycle number of 0 at multiple different temperatures to obtain the relationship between the battery capacity and voltage at different temperatures;

[0007] Performing multiple charge and discharge tests on a battery sample with a charge and discharge cycle number of 0 to obtain the relationship between the battery capacity and the number of charge and discharge cycles;

[0008] Based on the relationship between the battery capacity and voltage at different temperatures, and the relationship between the battery capacity and the number of charge and discharge cycles, determining a database of the battery capacity and voltage at each temperature and different numbers of charge and discharge cycles;

[0009] Obtaining the operating temperature, the number of cycles and the operating voltage of the battery to be tested, and looking up the corresponding battery capacity of the battery to be tested in the database.

[0010] Optionally, performing charge and discharge tests on a battery sample with a charge and discharge cycle number of 0 at multiple different temperatures to obtain the relationship between the battery capacity and voltage at different temperatures, including:

[0011] Performing constant current and constant voltage charging on a battery sample with a charge and discharge cycle number of 0 until the battery sample is fully charged;

[0012] Letting the fully charged battery sample stand at the test temperature for a preset duration;

[0013] The battery sample after standing is discharged at a constant current to the cut-off voltage, and the battery capacity and voltage during the discharge process are recorded.

[0014] Change the test temperature, and return to perform the step of charging a battery sample with 0 charge-discharge cycles at a constant current and constant voltage until the battery sample is fully charged, until the relationship between the battery capacity and voltage at multiple different temperatures is obtained.

[0015] Optionally, the preset duration is 2 - 5 hours.

[0016] Optionally, perform multiple charge-discharge tests on a battery sample with 0 charge-discharge cycles to obtain the relationship between the battery capacity and the number of charge-discharge cycles, including:

[0017] Charge a battery sample with 0 charge-discharge cycles at a constant current and constant voltage until the battery sample is fully charged;

[0018] Discharge the fully charged battery sample to the cut-off voltage and record the discharge capacity;

[0019] Return to perform the charging step, charge the discharged battery until the number of charge-discharge cycles reaches the preset number, and obtain the relationship between the battery capacity and the number of charge-discharge cycles.

[0020] Optionally, in the charge-discharge test, the condition for the battery sample to be fully charged is that the charging current is less than or equal to 0.02C.

[0021] Optionally, based on the relationship between the battery capacity and voltage at different temperatures, and the relationship between the battery capacity and the number of charge-discharge cycles, determine a database of the battery capacity and voltage at each temperature and different numbers of charge-discharge cycles, including:

[0022] Calculate the ratio of the battery capacity at each charge-discharge cycle to the initial capacity to obtain the capacity retention rate at each charge-discharge cycle;

[0023] Multiply the battery capacity in the relationship between the battery capacity and voltage at different temperatures by the capacity retention rate at each charge-discharge cycle to obtain a database of the battery capacity and voltage at each temperature and different numbers of charge-discharge cycles.

[0024] In a second aspect, the present invention also provides a lithium battery capacity determination device, including:

[0025] A first relationship determination module, configured to perform charge-discharge tests on a battery sample with 0 charge-discharge cycles at multiple different temperatures to obtain the relationship between the battery capacity and voltage at different temperatures;

[0026] A second relationship determination module, configured to perform multiple charge-discharge tests on a battery sample with 0 charge-discharge cycles to obtain the relationship between the battery capacity and the number of charge-discharge cycles;

[0027] A database determination module, configured to determine a database of battery capacity and voltage at different charge and discharge cycle numbers for each temperature based on the relationship between battery capacity and voltage at different temperatures and the relationship between battery capacity and the number of charge and discharge cycles.

[0028] A battery capacity determination module, configured to obtain the operating temperature, the number of cycles, and the operating voltage of the battery to be measured, and look up the corresponding battery capacity of the battery to be measured in the database.

[0029] In a third aspect, the present invention further provides an electronic device, including:

[0030] One or more processors;

[0031] A memory, configured to store one or more programs;

[0032] When the one or more programs are executed by the one or more processors, the one or more processors implement the lithium battery capacity determination method provided in the first aspect of the present invention.

[0033] In a fourth aspect, the present invention further provides a computer-readable storage medium, in which computer-executable instructions are stored, and when the computer-executable instructions are executed by a processor, they are used to implement the lithium battery capacity determination method provided in the first aspect of the present invention.

[0034] In a fifth aspect, the present invention further provides a computer program product, characterized in that it includes a computer program, and when the computer program is executed by a processor, it implements the lithium battery capacity determination method provided in the first aspect of the present invention.

[0035] The method for determining the capacity of a lithium battery provided by the present invention includes: performing charge and discharge tests on battery samples with 0 charge-discharge cycles at multiple different temperatures to obtain the relationship between battery capacity and voltage at different temperatures; performing multiple charge and discharge tests on battery samples with 0 charge-discharge cycles to obtain the relationship between battery capacity and charge-discharge cycle times; based on the relationship between battery capacity and voltage at different temperatures and the relationship between battery capacity and charge-discharge cycle times, determining a database of battery capacity and voltage at each temperature and different charge-discharge cycle times; obtaining the operating temperature, cycle times, and operating voltage of the battery to be tested, and looking up the corresponding battery capacity of the battery to be tested in the database; by extracting the test data of battery capacity and voltage at the full operating temperature range, establishing a database, and plotting voltage-capacity curves at different temperatures. Considering the influence of dynamic temperature changes makes the calculation of the capacity state more accurate. At the same time, starting from practical applications, considering the irreversible capacity loss during the charge and discharge cycle of the battery, exploring the relationship between the capacity retention rate and the number of cycles, and combining it with the relationship curves of voltage and energy at different temperatures to establish a database, so that the relationship curves of voltage and capacity at different temperatures for any number of cycles can be obtained. Due to the establishment of this curve graph and database, the capacity state is visualized, enabling the rapid calculation of the capacity state in any subsequent state, and more conveniently, real-time, and accurately predicting the capacity of the battery.

[0036] It should be understood that the content described in this part is not intended to identify the key or important features of the embodiments of the present invention, nor is it used to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. Brief Description of the Drawings

[0037] To more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0038] Figure 1 It is a flowchart of a method for determining the capacity of a lithium battery provided by an embodiment of the present invention;

[0039] Figure 2 It is a relationship diagram of battery capacity and voltage of a battery with 0 charge-discharge cycles at different temperatures provided by an embodiment of the present invention;

[0040] Figure 3 It is a relationship diagram of capacity retention rate and charge-discharge cycle times provided by an embodiment of the present invention;

[0041] Figure 4 It is a relationship diagram of battery capacity and voltage at different temperatures after 1000 cycles;

[0042] Figure 5 It is a curve graph showing the relationship between the battery capacity and voltage at a working temperature of T1 °C and a cycle number of N1 times;

[0043] Figure 6 It is a curve graph showing the relationship between the battery capacity and voltage at a working temperature of T2 °C and a cycle number of N2 times;

[0044] Figure 7 It is a schematic structural diagram of a lithium battery capacity determination device provided by an embodiment of the present invention;

[0045] Figure 8 It is a schematic structural diagram of an electronic device provided by an embodiment of the present invention.

[0046] Through the above-mentioned drawings, the clear embodiments of the present application have been shown, and there will be more detailed descriptions hereinafter. These drawings and textual descriptions are not intended to limit the scope of the concept of the present application in any way, but to illustrate the concept of the present application to those skilled in the art by referring to specific embodiments. Detailed Embodiments

[0047] In order to enable the personnel in the technical field to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present invention.

[0048] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and do not necessarily need to describe a specific order or sequence. It should be understood that such used data can be interchanged under appropriate circumstances so that the embodiments of the present invention described here can be implemented in an order other than those illustrated or described here. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device including a series of steps or units does not necessarily have to be limited to those clearly listed steps or units, but may include other steps or units not clearly listed or inherent to these process, method, product or device.

[0049] The battery capacity is closely related to the surrounding temperature, showing an inverse function relationship. The capacity indicated on the battery is calculated based on the standard temperature (air temperature) of 25°C. When the temperature drops by 1°C, the relative capacity decreases by approximately 0.8%. This explains why the capacity of electric vehicle batteries becomes smaller in winter. Understanding the relationship between capacity and temperature is of great significance for judging the repair results during battery repair. For example, when the repaired battery discharges at 5A for 100 minutes at an air temperature or surrounding temperature of 0°C, without considering the environmental temperature factor, the calculated capacity is about 8AH. However, since the environmental temperature is 25°C lower than the standard temperature, the capacity of the battery itself has decreased by about 20%. Considering this factor, after calculation, this battery should reach the standard battery capacity of 10AH.

[0050] When the battery temperature decreases, its capacity will also decrease significantly for the following reasons: 1. The viscosity of the electrolyte increases and it is not easy to diffuse, the conductivity decreases, and the chemical reaction rate of the positive and negative active substances slows down. 2. The impedance of the electrolyte / electrode interface film and the charge transfer impedance increase; the migration rate of lithium ions decreases.

[0051] The capacity of the battery is also closely related to the number of its charge and discharge cycles. It is an inevitable phenomenon that capacity attenuation and loss occur during the battery cycling process. The main reasons for the cyclic capacity attenuation are as follows.

[0052] 1. The chemical structure of the substances inside the battery deteriorates: The normal attenuation of the chemical raw materials inside the battery will lead to the deterioration of the chemical structure of the substances, which is the main reason for the battery capacity attenuation.

[0053] 2. The number of active lithium ions decreases: During the charge and discharge cycle of the lithium battery, some lithium ions are embedded in the negative electrode carbon and cannot be deintercalated, resulting in fewer freely moving lithium ions, a decrease in the discharge ability, which is manifested as a decrease in capacity.

[0054] 3. The internal resistance increases: As the lithium battery undergoes charge and discharge, oxidation attenuation of the raw materials occurs, which also leads to an increase in the internal resistance of the entire battery. With the increase in internal resistance, more power is consumed during the discharge process, and the amount of electricity that can be discharged becomes less, which is manifested as a decrease in capacity.

[0055] 4. Lithium plating: As the lithium battery is used and undergoes charge and discharge, lithium plating occurs inside the battery, which reduces the number of active lithium ions and the ability to store electricity, resulting in a decrease in capacity.

[0056] 5. The electrolyte decreases: As the battery is used, the electrolyte inside the battery undergoes complex chemical reactions and is gradually consumed. The more the electrolyte is consumed, the more the conductive ions, conductivity, and electricity storage ability decrease, thus also leading to a decrease in the battery capacity.

[0057] Combined with the actual application of new energy vehicles, their batteries are greatly affected by temperature and the number of charge-discharge cycles. For example, when the vehicle starts, the ambient temperature of its battery is -10°C, but as the vehicle is continuously used, the battery temperature rises to 10°C. After the vehicle battery has been charged and discharged 300 cycles after being used for a period of time, the battery capacity has decreased compared to the beginning. This phenomenon is more prominent in large-capacity batteries. Therefore, it is necessary to explore the influence of temperature and the number of cycles on the capacity state of new energy vehicle batteries.

[0058] Figure 1 The flowchart of a method for determining the capacity of a lithium battery provided by an embodiment of the present invention. This embodiment is applicable to determining the capacity of a lithium battery according to the real-time state of the battery to improve the accuracy of the capacity. This method can be executed by the lithium battery capacity determination device provided by the embodiment of the present invention. The device can be implemented in software and / or hardware and is usually configured in a computer device, such as Figure 1 As shown, the method for determining the capacity of a lithium battery specifically includes the following steps:

[0059] S101. Perform charge-discharge tests on battery samples with a charge cycle number of 0 at multiple different temperatures to obtain the relationship between battery capacity and voltage at different temperatures.

[0060] In the embodiment of the present invention, in order to explore the relationship between battery capacity and voltage at different temperatures, the method of controlling variables is adopted. Each time a charge-discharge test is performed, the charge cycle number of the battery sample used for testing is controlled to be 0, so as to avoid the influence of the charge cycle number. By performing charge-discharge tests on battery samples with a charge cycle number of 0 at multiple different temperatures, specifically, at different temperatures, discharge the battery samples with a charge cycle number of 0 and fully charged. During the battery discharge process, record the battery capacity and voltage, and fit the battery capacity and voltage data at the same temperature to obtain the relationship between battery capacity and voltage at each temperature.

[0061] In some embodiments of the present invention, the specific implementation process of the above step S101 is:

[0062] 1. Perform constant current and constant voltage charging on a battery sample with a charge cycle number of 0 until the battery sample is fully charged.

[0063] In an embodiment of the present invention, a fresh battery sample with 0 charge cycles is taken for constant current and constant voltage charging until the battery sample is fully charged. In some embodiments of the present invention, the condition for the battery sample to be fully charged is that the charging current is less than or equal to the cut-off current of 0.02C. Here, C is the maximum current output by the charger. During the charging process of the battery sample, usually a small current of 0.1C is first used for pre-charging. After the battery voltage exceeds the first threshold value V1, the battery sample can withstand fast charging with a large current, and constant current 1C charging is used to quickly supplement the power. When the voltage of the battery sample approaches the second threshold value V2, the acceptable current of the battery sample decreases. If constant current charging is used again, the heat generation is very large, and constant voltage charging should be used instead. During constant voltage charging, the current continuously decreases. When the current decreases to 0.02C, the charger stops charging. It should be noted that the above condition for the battery sample to be fully charged is an exemplary illustration of the present invention. In other embodiments of the present invention, the condition for the battery sample to be fully charged can also be other conditions, and the embodiments of the present invention do not limit this here.

[0064] 2. Place the fully charged battery sample at the test temperature for a preset duration.

[0065] In an embodiment of the present invention, the fully charged battery sample is placed at a certain test temperature for a preset duration to make it fully stable at this test temperature. Exemplarily, in some embodiments of the present invention, the fully charged battery sample can be placed in an incubator for a preset duration, and the incubator can adjust the temperature.

[0066] In some embodiments of the present invention, the preset duration can be 2 - 5 hours. Preferably, in a specific embodiment of the present invention, the preset duration is 3 hours.

[0067] 3. Discharge the battery sample after standing at a constant current until the cut-off voltage, and record the battery capacity and voltage during the discharge process.

[0068] The battery sample after standing is discharged at a constant current until the voltage of the battery sample reaches the cut-off voltage. Exemplarily, a constant current discharge with a discharge current of 1C is used for the battery sample after standing until the discharge is cut off. During the discharge process, the battery capacity corresponding to each voltage at this test temperature is recorded.

[0069] 4. Change the test temperature, and return to execute the step of performing constant current and constant voltage charging on a battery sample with 0 charge cycles until the battery sample is fully charged until the relationship between the battery capacity and voltage at multiple different temperatures is obtained.

[0070] Change the test temperature and repeat the foregoing steps to obtain the battery capacity corresponding to each voltage at another test temperature. Repeat this process until the relationships between the battery capacity and voltage at multiple different temperatures are obtained. In some embodiments of the present invention, the battery sample is discharged at -30°C, -20°C, -10°C, 0°C, 25°C, and 60°C respectively, and the battery capacity and voltage at these temperatures are recorded. In other embodiments of the present invention, in order to improve the data accuracy, the step temperature when changing the test temperature can be set as needed. For example, charge and discharge tests are performed every 1°C, 2°C, or 5°C. The embodiments of the present invention do not make limitations here.

[0071] In the embodiments of the present invention, in order to avoid the influence of the number of charge and discharge cycles on the capacity, the voltage and battery capacity at each temperature are obtained by discharging a fresh battery (the number of charge cycles is 0), that is, after changing the test temperature, a new battery sample with a charge cycle number of 0 is taken instead of the previous battery sample. In this way, the accuracy of the test data can be improved, and thus the accuracy of the final battery capacity can be improved.

[0072] For the battery capacity and voltage obtained at each test temperature, taking the voltage as the independent variable, the functional relationship between the battery capacity and the voltage is fitted. In this way, the relationships between the battery capacity and voltage at multiple different temperatures are obtained. Figure 2 This is the relationship diagram between the battery capacity and voltage of a battery with 0 charge cycles at different temperatures provided by the embodiments of the present invention. As Figure 2 shown, taking the battery voltage of 4.2V as an example, at 25°C and 60°C, the battery capacity is not greatly affected and both reach 20Ah. Under the conditions of -30°C, -20°C, -10°C, and 0°C, the battery capacity is significantly reduced compared to the 25°C condition, and the lower the temperature, the greater the reduction in capacity.

[0073] S102: Perform multiple charge and discharge tests on a battery sample with 0 charge cycles to obtain the relationship between the battery capacity and the number of charge and discharge cycles.

[0074] In the embodiments of the present invention, multiple charge and discharge tests are performed on a battery sample with 0 charge cycles, the battery capacity and the number of charge and discharge cycles are recorded, and the number of multiple charge and discharge cycles and the corresponding battery capacity are fitted to obtain the relationship between the battery capacity and the number of charge and discharge cycles.

[0075] Exemplarily, in some embodiments of the present invention, the specific implementation process of the above step S102 is as follows:

[0076] 1. Perform constant current and constant voltage charging on a battery sample with 0 charge cycles until the battery sample is fully charged.

[0077] In an embodiment of the present invention, a fresh battery sample with 0 charge-discharge cycles is taken for constant current and constant voltage charging until the battery sample is fully charged. In some embodiments of the present invention, the condition for the battery sample to be fully charged is that the charging current is less than or equal to the cut-off current of 0.02C. Here, C is the maximum current output by the charger.

[0078] 2. Discharge the fully charged battery sample to the cut-off voltage and record the discharge capacity.

[0079] In an embodiment of the present invention, the fully charged battery sample is left standing for a preset duration to make it fully stable. In some embodiments of the present invention, the preset duration can be 2 - 5 hours. Preferably, in a specific embodiment of the present invention, the preset duration is 3 hours. The standing battery sample is subjected to constant current discharge until the voltage of the battery sample reaches the cut-off voltage. Exemplarily, a discharge current of 1C is used to perform constant current discharge on the standing battery sample until discharge is terminated. At the end of the discharge, record its discharge capacity.

[0080] 3. Return to execute the charging step, charge the emptied battery sample to the fully charged state until the charge-discharge cycle count reaches the preset number of times, and obtain the relationship between the battery capacity and the charge-discharge cycle count.

[0081] After the discharge is completed, recharge the battery sample to the fully charged state again. Repeat the above charge-discharge process until the charge-discharge cycle count reaches the preset number of times. Here, one charge + discharge is one cycle. Obtain the discharge capacity (i.e., the battery capacity) after each cycle, and fit the multiple charge-discharge cycle counts and the corresponding battery capacities to obtain the relationship between the battery capacity and the charge-discharge cycle count.

[0082] S103. Based on the relationship between the battery capacity and voltage at different temperatures, and the relationship between the battery capacity and the charge-discharge cycle count, determine the database of the battery capacity and voltage at different charge-discharge cycle counts for each temperature.

[0083] After obtaining the relationship between the battery capacity and voltage at different temperatures, and the relationship between the battery capacity and the charge-discharge cycle count, based on the relationship between the battery capacity and voltage at different temperatures, and the relationship between the battery capacity and the charge-discharge cycle count, the database of the battery capacity and voltage at different charge-discharge cycle counts for each temperature can be determined.

[0084] Exemplarily, the above step S103 includes the following sub-steps:

[0085] 1. Calculate the ratio of the battery capacity to the initial capacity at each charge-discharge cycle count to obtain the capacity retention rate at each charge-discharge cycle count.

[0086] After obtaining the relationship between the battery capacity and the number of charge-discharge cycles, calculate the ratio of the battery capacity at each charge-discharge cycle to the initial capacity to obtain the capacity retention rate at each charge-discharge cycle. Figure 3 The graph showing the relationship between the capacity retention rate and the number of charge-discharge cycles provided by the embodiment of the present invention is as Figure 3 shown. The more the number of charge-discharge cycles, the smaller the capacity retention rate of the battery sample.

[0087] 2. Multiply the battery capacity in the relationship between the battery capacity and voltage at different temperatures by the capacity retention rate at each charge-discharge cycle to obtain a database of the battery capacity and voltage at each temperature and different charge-discharge cycles.

[0088] Since the capacity-voltage relationship curves at different temperatures are the same for each cycle number, in actual applications, the relationship graph of voltage-capacity at different temperatures when the fresh battery is cycled 0 times can be used as a reference. Combining with the capacity retention rate curve, calculate the capacity retention rate, and multiply the capacity retention rate by the original data when cycling 0 times, then the capacity-voltage relationship curve graph at the current cycle number can be obtained. Figure 1 Exemplarily, by querying the graph of the capacity retention rate and the number of cycles, it can be known that the capacity retention rate of a certain battery sample is 85% after 1000 cycles. Multiply 85% by the battery capacity in the relationship between the battery capacity and voltage at different temperatures when cycling 0 times, then the relationship between the battery capacity and voltage at different temperatures after 1000 cycles can be obtained.

[0089] For the graph showing the relationship between the battery capacity and voltage at different temperatures after 1000 cycles, as Figure 4 shown, Figure 4 the ordinate data of the curve in Figure 4 is generally multiplied by 85% on the basis of Figure 2 .

[0090] S104. Obtain the working temperature, number of cycles, and working voltage of the battery to be tested, and find the corresponding battery capacity of the battery to be tested from the database.

[0091] In actual applications, obtain the working temperature, number of cycles, and working voltage of the currently tested battery, and find the corresponding battery capacity of the battery to be tested from the database based on the working temperature, number of cycles, and working voltage. Figure 5 For the graph showing the relationship between the battery capacity and voltage at a working temperature of T1 °C and a number of cycles of N1 times. Exemplarily, if the battery to be tested is at T1 °C, the number of cycles is N1 times, and the current voltage is V1, first find the relationship between the battery capacity and voltage at different temperatures with the number of cycles of N1 times from the database, then determine the relationship curve of the battery capacity and voltage corresponding to the test temperature of T1 °C, as Figure 5 shown, and then find the corresponding battery capacity C1 when the voltage is V1.Figure 6 It is a relationship curve graph of battery capacity and voltage at a working temperature of T2 °C and a cycle number of N2 times. Exemplarily, if the battery under test is at T2 °C, the cycle number is N2 times, and the current voltage is V2, then first find the relationship between battery capacity and voltage at different temperatures with a cycle number of N2 times from the database, and then determine the relationship curve of battery capacity and voltage corresponding to the test temperature of T2 °C, as Figure 6 shown, and then find the corresponding battery capacity C2 when the voltage is V2.

[0092] The lithium battery capacity determination method provided by the embodiments of the present invention includes: performing charge and discharge tests on battery samples with a charge cycle number of 0 at multiple different temperatures to obtain the relationship between battery capacity and voltage at different temperatures, performing multiple charge and discharge tests on battery samples with a charge cycle number of 0 to obtain the relationship between battery capacity and charge and discharge cycle number, based on the relationship between battery capacity and voltage at different temperatures, and the relationship between battery capacity and charge and discharge cycle number, determining the database of battery capacity and voltage at each temperature and different charge and discharge cycle numbers, obtaining the working temperature, cycle number, and working voltage of the battery under test, and looking up the corresponding battery capacity of the battery under test from the database. By extracting the test data of battery capacity and voltage at the full working temperature, establishing a database, and drawing voltage-capacity curves at different temperatures, the influence of temperature dynamic changes is considered, making the calculation of the capacity state more accurate. At the same time, from the actual application, the irreversible capacity loss during the charge and discharge cycle of the battery is considered, the relationship between the capacity retention rate and the number of cycles is explored, and it is combined with the relationship curves of voltage and energy at different temperatures to establish a database, so that the relationship curves of voltage and capacity at different temperatures for any number of cycles can be obtained. Due to the establishment of this curve graph and database, the capacity state is visualized, and the capacity state in any subsequent state can be quickly calculated, more conveniently, real-time, and accurately predicting the battery capacity.

[0093] The embodiments of the present invention also provide a lithium battery capacity determination device, Figure 7 which is a structural schematic diagram of a lithium battery capacity determination device provided by the embodiments of the present invention, as Figure 7 shown. The lithium battery capacity determination device includes:

[0094] The first relationship determination module 201 is used to perform charge and discharge tests on battery samples with a charge cycle number of 0 at multiple different temperatures to obtain the relationship between battery capacity and voltage at different temperatures;

[0095] The second relationship determination module 202 is used to perform multiple charge and discharge tests on battery samples with a charge cycle number of 0 to obtain the relationship between battery capacity and charge and discharge cycle number;

[0096] A database determination module 203, configured to determine a database of battery capacity and voltage at different charge and discharge cycle numbers for each temperature based on the relationship between battery capacity and voltage at different temperatures and the relationship between battery capacity and charge and discharge cycle numbers.

[0097] A battery capacity determination module 204, configured to obtain the operating temperature, cycle number, and operating voltage of a battery to be measured, and look up the corresponding battery capacity of the battery to be measured from the database.

[0098] In some embodiments of the present invention, the first relationship determination module 201 includes:

[0099] A first charging unit, configured to perform constant current and constant voltage charging on a battery sample with a charge and discharge cycle number of 0 until the battery sample is fully charged.

[0100] A standing unit, configured to let the fully charged battery sample stand at the test temperature for a preset duration.

[0101] A first discharging unit, configured to discharge the standing battery sample at a constant current to the cut-off voltage, and record the battery capacity and voltage during the discharging process.

[0102] A first cycling unit, configured to change the test temperature, and return to execute the step of performing constant current and constant voltage charging on a battery sample with a charge and discharge cycle number of 0 until the battery sample is fully charged, until the relationships between battery capacity and voltage at multiple different temperatures are obtained.

[0103] In some embodiments of the present invention, the preset duration is 2 - 5 hours.

[0104] In some embodiments of the present invention, the second relationship determination module 202 includes:

[0105] A second charging unit, configured to perform constant current and constant voltage charging on a battery sample with a charge and discharge cycle number of 0 until the battery sample is fully charged.

[0106] A second discharging unit, configured to discharge the fully charged battery sample to the cut-off voltage, and record the discharge capacity.

[0107] A second cycling unit, configured to return to execute the charging step, charge the discharged battery sample until the charge and discharge cycle number reaches a preset number, and obtain the relationship between battery capacity and charge and discharge cycle number.

[0108] In some embodiments of the present invention, in the charge and discharge test, the condition for the battery sample to be fully charged is that the charging current is less than or equal to 0.02C.

[0109] In some embodiments of the present invention, the database determination module 203 includes:

[0110] A capacity retention rate calculation unit for calculating the ratio of the battery capacity at each charge-discharge cycle number to the initial capacity, so as to obtain the capacity retention rate at each charge-discharge cycle number;

[0111] A database determination unit for multiplying the battery capacity in the relationship between the battery capacity and voltage at different temperatures by the capacity retention rate at each charge-discharge cycle number to obtain a database of the battery capacity and voltage at each temperature and different charge-discharge cycle numbers.

[0112] The above lithium battery capacity determination device can execute the lithium battery capacity determination method provided by any embodiment of the present application, and has corresponding functional modules and beneficial effects for executing the lithium battery capacity determination method.

[0113] Figure 8 A structural schematic diagram of an electronic device provided by an embodiment of the present invention. The electronic device is intended to represent various forms of digital computers, such as, a laptop computer, a desktop computer, a workbench, a personal digital assistant, a server, a blade server, a mainframe computer, and other suitable computers. The electronic device can also represent various forms of mobile devices, such as, a personal digital processor, a cellular phone, a smart phone, a wearable device (such as a helmet, glasses, a watch, etc.) and other similar computing devices. The components shown herein, their connections and relationships, and their functions are only examples and are not intended to limit the implementation of the present invention described and / or claimed herein.

[0114] As Figure 8 shown, the electronic device 10 includes at least one processor 11, and a memory communicatively connected to at least one processor 11, such as a read-only memory (ROM) 12, a random access memory (RAM) 13, etc. Among them, the memory stores a computer program executable by at least one processor. The processor 11 can execute various appropriate actions and processes according to the computer program stored in the read-only memory (ROM) 12 or the computer program loaded from the storage unit 18 into the random access memory (RAM) 13. In the RAM 13, various programs and data required for the operation of the electronic device 10 can also be stored. The processor 11, the ROM 12, and the RAM 13 are connected to each other through a bus 14. The input / output (I / O) interface 15 is also connected to the bus 14.

[0115] Multiple components in the electronic device 10 are connected to the I / O interface 15, including: an input unit 16, such as a keyboard, a mouse, etc.; an output unit 17, such as various types of displays, speakers, etc.; a storage unit 18, such as a disk, an optical disc, etc.; and a communication unit 19, such as a network card, a modem, a wireless communication transceiver, etc. The communication unit 19 allows the electronic device 10 to exchange information / data with other devices through a computer network such as the Internet and / or various telecommunication networks.

[0116] The processor 11 can be various general-purpose and / or special-purpose processing components with processing and computing capabilities. Some examples of the processor 11 include, but are not limited to, a central processing unit (CPU), a graphics processing unit (GPU), various dedicated artificial intelligence (AI) computing chips, various processors running machine learning model algorithms, a digital signal processor (DSP), and any suitable processor, controller, microcontroller, etc. The processor 11 executes the various methods and processes described above, such as the lithium battery capacity determination method.

[0117] In some embodiments, the lithium battery capacity determination method can be implemented as a computer program, which is tangibly included in a computer-readable storage medium, such as the storage unit 18. In some embodiments, part or all of the computer program can be loaded and / or installed onto the electronic device 10 via the ROM 12 and / or the communication unit 19. When the computer program is loaded into the RAM 13 and executed by the processor 11, one or more steps of the lithium battery capacity determination method described above can be executed. Alternatively, in other embodiments, the processor 11 can be configured to execute the lithium battery capacity determination method by any other suitable means (e.g., by means of firmware).

[0118] Various embodiments of the systems and techniques described above herein can be implemented in digital electronic circuit systems, integrated circuit systems, field-programmable gate arrays (FPGAs), application-specific integrated circuits (ASICs), application-specific standard products (ASSPs), systems-on-a-chip (SOCs), complex programmable logic devices (CPLDs), computer hardware, firmware, software, and / or combinations thereof. These various embodiments can include: implemented in one or more computer programs that can be executed and / or interpreted on a programmable system including at least one programmable processor, which can be a special-purpose or general-purpose programmable processor that can receive data and instructions from a storage system, at least one input device, and at least one output device, and transmit the data and instructions to the storage system, the at least one input device, and the at least one output device.

[0119] The computer program for implementing the method of the present invention can be written in any combination of one or more programming languages. These computer programs can be provided to the processor of a general-purpose computer, a special-purpose computer, or other programmable data processing device, such that when the computer program is executed by the processor, the functions / operations specified in the flowchart and / or block diagram are implemented. The computer program can be executed entirely on the machine, partially on the machine, executed partially on the machine and partially on a remote machine as an independent software package, or executed entirely on a remote machine or server.

[0120] In the context of the present invention, a computer-readable storage medium can be a tangible medium that can contain or store a computer program for use by or in connection with an instruction execution system, apparatus, or device. The computer-readable storage medium can include, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatus, or devices, or any suitable combination of the foregoing. Alternatively, the computer-readable storage medium can be a machine-readable signal medium. More specific examples of the machine-readable storage medium would include an electrical connection based on one or more wires, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0121] To provide for interaction with a user, the systems and techniques described herein can be implemented on an electronic device having: a display device (e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor) for displaying information to the user; and a keyboard and a pointing device (e.g., a mouse or a trackball) by which the user can provide input to the electronic device. Other kinds of devices can also be used to provide for interaction with the user; for example, feedback provided to the user can be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback); and input from the user can be received in any form (including acoustic input, speech input, or tactile input).

[0122] The systems and techniques described herein can be implemented in a computing system that includes backend components (e.g., as a data server), or a computing system that includes middleware components (e.g., an application server), or a computing system that includes frontend components (e.g., a user computer having a graphical user interface or a web browser through which the user can interact with an implementation of the systems and techniques described herein), or a computing system that includes any combination of such backend components, middleware components, or frontend components. The components of the system can be interconnected by any form or medium of digital data communication (e.g., a communication network). Examples of communication networks include: a local area network (LAN), a wide area network (WAN), a blockchain network, and the Internet.

[0123] A computing system may include a client and a server. The client and the server are generally far from each other and usually interact via a communication network. The relationship between the client and the server is generated by computer programs running on respective computers and having a client-server relationship with each other. The server may be a cloud server, also known as a cloud computing server or a cloud host, which is a host product in the cloud computing service system, solving the defects of large management difficulty and weak business scalability existing in traditional physical hosts and VPS services.

[0124] An embodiment of the present invention also provides a computer program product, including a computer program which, when executed by a processor, implements the lithium battery capacity determination method provided in any embodiment of the present application.

[0125] In the process of implementing the computer program product, computer program code for performing the operations of the present invention can be written in one or more programming languages or combinations thereof. The programming languages include object-oriented programming languages such as Java, Smalltalk, C++, and also include conventional procedural programming languages such as the "C" language or similar programming languages. The program code can be executed entirely on the user's computer, partially on the user's computer, executed as an independent software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In the case of a remote computer, the remote computer can be connected to the user's computer through any type of network - including a local area network (LAN) or a wide area network (WAN) - or can be connected to an external computer (for example, by using an Internet service provider to connect through the Internet).

[0126] It should be understood that various forms of the processes shown above can be used, steps can be reordered, added or deleted. For example, the steps described in the present invention can be executed in parallel, sequentially, or in a different order, as long as the desired results of the technical solution of the present invention can be achieved, and no limitation is made herein.

[0127] The above specific embodiments do not constitute a limitation on the protection scope of the present invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for determining the capacity of a lithium battery, characterized in that, Comprising: Performing charge and discharge tests on battery samples with 0 charge-discharge cycles at multiple different temperatures to obtain the relationship between battery capacity and voltage at different temperatures; Performing multiple charge and discharge tests on battery samples with 0 charge-discharge cycles to obtain the relationship between battery capacity and charge-discharge cycle times; Based on the relationship between battery capacity and voltage at different temperatures and the relationship between battery capacity and charge-discharge cycle times, determining a database of battery capacity and voltage at each temperature and different charge-discharge cycle times; Obtaining the working temperature, cycle times, and working voltage of the battery to be tested, and looking up the corresponding battery capacity of the battery to be tested in the said database; Based on the relationship between battery capacity and voltage at different temperatures and the relationship between battery capacity and charge-discharge cycle times, determining a database of battery capacity and voltage at each temperature and different charge-discharge cycle times, including: Calculating the ratio of the battery capacity at each charge-discharge cycle time to the initial capacity to obtain the capacity retention rate at each charge-discharge cycle time; Multiplying the battery capacity in the relationship between battery capacity and voltage at different temperatures by the capacity retention rate at each charge-discharge cycle time to obtain a database of battery capacity and voltage at each temperature and different charge-discharge cycle times.

2. The method for determining the capacity of a lithium battery according to claim 1, wherein Performing charge and discharge tests on battery samples with 0 charge-discharge cycles at multiple different temperatures to obtain the relationship between battery capacity and voltage at different temperatures, including: Performing constant current and constant voltage charging on a battery sample with 0 charge-discharge cycles until the battery sample is fully charged; Letting the fully charged battery sample stand at the test temperature for a preset duration; Discharging the standing battery sample at a constant current to the cut-off voltage, and recording the battery capacity and voltage during the discharging process; Changing the test temperature, and returning to perform the step of performing constant current and constant voltage charging on a battery sample with 0 charge-discharge cycles until the battery sample is fully charged until the relationship between battery capacity and voltage at multiple different temperatures is obtained.

3. The method for determining the capacity of a lithium battery according to claim 2, wherein The preset duration is 2 - 5 hours.

4. The method for determining the capacity of a lithium battery according to any one of claims 1-3, characterized in that, Performing multiple charge and discharge tests on battery samples with 0 charge-discharge cycles to obtain the relationship between battery capacity and charge-discharge cycle times, including: Performing constant current and constant voltage charging on a battery sample with 0 charge-discharge cycles until the battery sample is fully charged; Discharging the fully charged battery sample to the cut-off voltage, and recording the discharge capacity; Returning to perform the charging step, charging the emptied battery sample until the charge-discharge cycle times reach the preset times to obtain the relationship between battery capacity and charge-discharge cycle times.

5. The method for determining the capacity of a lithium battery according to claim 4, wherein In the charge and discharge test, the condition for the battery sample to be fully charged is that the charging current is less than or equal to 0.02C.

6. A lithium battery capacity determination device, characterized in that, Comprising: A first relationship determination module, configured to perform charge and discharge tests on battery samples with 0 charge-discharge cycles at multiple different temperatures to obtain the relationship between battery capacity and voltage at different temperatures; A second relationship determination module, configured to perform multiple charge and discharge tests on battery samples with 0 charge-discharge cycles to obtain the relationship between battery capacity and charge-discharge cycle times; A database determination module, configured to determine a database of battery capacity and voltage at each temperature and different charge-discharge cycle numbers based on the relationship between battery capacity and voltage at different temperatures and the relationship between battery capacity and charge-discharge cycle numbers; A battery capacity determination module, configured to obtain the operating temperature, cycle number, and operating voltage of a battery to be measured, and look up the corresponding battery capacity of the battery to be measured in the database; The database determination module includes: A capacity retention rate calculation unit, configured to calculate the ratio of the battery capacity at each charge-discharge cycle number to the initial capacity to obtain the capacity retention rate at each charge-discharge cycle number; A database determination unit, configured to multiply the battery capacity in the relationship between battery capacity and voltage at different temperatures by the capacity retention rate at each charge-discharge cycle number to obtain a database of battery capacity and voltage at each temperature and different charge-discharge cycle numbers.

7. An electronic device, characterized in that, Including: One or more processors; A memory, configured to store one or more programs; When the one or more programs are executed by the one or more processors, the one or more processors implement the lithium battery capacity determination method according to any one of claims 1-5.

8. A computer-readable storage medium, characterized in that, Computer-executable instructions are stored in the computer-readable storage medium, and when the computer-executable instructions are executed by a processor, they are used to implement the lithium battery capacity determination method according to any one of claims 1-5.

9. A computer program product, characterized in that, Including a computer program, which when executed by a processor implements the lithium battery capacity determination method according to any one of claims 1-5.

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