A method for calculating charging time and equivalent charging rate of a lithium ion battery, an electronic device, and a medium

Abstract

This invention discloses a method for calculating the charging time and equivalent charging rate of a lithium-ion battery, as well as an electronic device and a dielectric material. The method may include: acquiring battery information and target operating condition parameters; constructing an electro-thermal coupling model based on the battery information and target operating condition parameters; simulating the target operating condition using the electro-thermal coupling model, and calculating the charging time and equivalent charging rate under the target operating condition. This invention predicts the charging process by building an electro-thermal coupling model of the battery, combined with actual heat dissipation conditions and the initial state of the battery, and outputs the charging time and equivalent charging rate.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery calculation technology, and more specifically, to a method for calculating the charging time and equivalent charging rate of a lithium-ion battery, as well as an electronic device and a medium. Background Technology

[0002] Over the past decade or so of development in the power battery industry, market demands for battery energy density and fast-charging performance have been steadily increasing. Automakers need to quickly and accurately evaluate the fast-charging performance of battery suppliers' samples; specifically, this involves obtaining the battery's charging time and equivalent charging rate under real-world conditions.

[0003] Battery charging rates typically change in real-time based on battery temperature and state of charge (SOC) / voltage, leading to several challenges in evaluating fast-charging performance. First, conventional testing equipment does not support real-time switching of charging current based on temperature and SOC / voltage, making it impossible to obtain accurate charging times and equivalent charging rates. Although battery packs can be accurately tested in conjunction with battery management systems, sample and testing costs are high, and sample preparation cycles are lengthy. Second, suppliers typically do not provide battery electrochemical parameters, preventing automakers from building electrochemical models. Finally, automakers can build equivalent circuit models of the battery to predict charging performance, but building such models requires extensive cell testing, resulting in long testing cycles. In summary, currently, there is a lack of fast, efficient, and effective methods for evaluating battery charging times and equivalent charging rates.

[0004] Semi-solid-state batteries, as a future trend in lithium-ion battery development, have attracted widespread attention from automakers and battery suppliers. These batteries typically have higher internal resistance than liquid lithium-ion batteries, resulting in greater temperature rise during charging. Therefore, a more accurate method for evaluating charging time and equivalent charge rate is needed for semi-solid-state batteries.

[0005] Currently, a method for calculating the charging time and equivalent charging rate of lithium-ion batteries still needs to be developed.

[0006] The information disclosed in the background section of this invention is intended only to enhance the understanding of the general background of this invention, and should not be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art. Summary of the Invention

[0007] This invention proposes a method for calculating the charging time and equivalent charging rate of lithium-ion batteries, as well as an electronic device and a medium. It can build an electro-thermal coupling model of the battery, predict the charging process by combining actual heat dissipation conditions and the initial state of the battery, and output the charging time and equivalent charging rate.

[0008] In a first aspect, embodiments of this disclosure provide a method for calculating the charging time and equivalent charging rate of a lithium-ion battery, including: Obtain battery information and target operating condition parameters; An electro-thermal coupling model is constructed based on battery information and target operating condition parameters; The target operating condition is simulated using an electro-thermal coupling model, and the charging time and equivalent charging rate under the target operating condition are calculated.

[0009] Preferably, the battery information includes battery specific heat capacity, battery mass, 1C current, battery capacity, battery open-circuit voltage, maximum charging rate, and battery internal resistance.

[0010] Preferably, the target operating condition parameters include battery heat dissipation area, convective heat transfer coefficient, initial SOC, initial temperature, and cutoff SOC.

[0011] Preferably, constructing an electro-thermal coupling model based on battery information and target operating condition parameters includes: Construct electrical and thermal models separately; The coupling between the electrical and thermal models is achieved through parameter transfer. The electrical model transfers current and internal resistance to the thermal model, and the thermal model transfers temperature to the electrical model.

[0012] Preferably, the electrical model is:

[0013] In the formula, U is the charging voltage, T is the battery temperature, t is the charging time, U0 is the battery open-circuit voltage, I_1C is the 1C current, C_rate is the maximum charging rate, R is the battery internal resistance, SOC0 is the initial SOC, and Capacity is the battery capacity.

[0014] Preferably, the thermal model is:

[0015] Where Cp is the specific heat capacity of the battery, m is the mass of the battery, h is the convective heat transfer coefficient, S is the heat dissipation area of ​​the battery, and T0 is the initial temperature.

[0016] Preferably, the target operating condition is simulated using an electro-thermal coupling model to obtain a curve showing the actual charging rate changing over time, and the maximum time in the curve is the charging time for calculating the target operating condition.

[0017] Preferably, the formula for calculating the equivalent charging rate C_equi is as follows:

[0018] Where C_equi is the equivalent charging rate, This refers to the charging time.

[0019] Secondly, embodiments of this disclosure also provide an electronic device, the electronic device comprising: Memory, which stores executable instructions; A processor that executes the executable instructions in the memory to implement the method for calculating the charging time and equivalent charging rate of the lithium-ion battery.

[0020] Thirdly, this disclosure also provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the method for calculating the charging time and equivalent charging rate of the lithium-ion battery.

[0021] Its beneficial effects are as follows: This invention considers the impact of temperature changes on charging performance during the charging process of semi-solid-state batteries, and builds a battery electro-thermal coupling model to predict the battery charging process. No additional battery testing and battery parameters are required; the fast charging performance of the battery can be quickly evaluated using only the battery information provided by the supplier.

[0022] The methods and apparatus of the present invention have other features and advantages that will be apparent from or will be set forth in detail in the accompanying drawings and following detailed description, which together serve to explain the particular principles of the invention. Attached Figure Description

[0023] The above and other objects, features and advantages of the present invention will become more apparent from the more detailed description of exemplary embodiments of the invention in conjunction with the accompanying drawings, wherein the same reference numerals generally represent the same parts.

[0024] Figure 1 A flowchart illustrating the steps of a method for calculating the charging time and equivalent charging rate of a lithium-ion battery according to an embodiment of the present invention is shown.

[0025] Figure 2 A schematic diagram of the open-circuit voltage curve of a ternary-graphite system battery according to Embodiment 1 of the present invention is shown.

[0026] Figure 3 A schematic diagram of the charging rate variation of a ternary-graphite system battery according to Embodiment 1 of the present invention is shown.

[0027] Figure 4 A schematic diagram showing the charging temperature and voltage variations of a ternary-graphite system battery according to Embodiment 1 of the present invention is shown.

[0028] Figure 5 A schematic diagram of the open-circuit voltage curve of the lithium iron phosphate-graphite system battery according to Embodiment 2 of the present invention is shown.

[0029] Figure 6 A schematic diagram of the charging rate variation of the lithium iron phosphate-graphite system battery according to Embodiment 2 of the present invention is shown.

[0030] Figure 7 A schematic diagram showing the charging temperature and voltage variations of a lithium iron phosphate-graphite battery according to Embodiment 2 of the present invention is shown. Detailed Implementation

[0031] Preferred embodiments of the invention will now be described in more detail. While preferred embodiments of the invention are described below, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein.

[0032] Figure 1 A flowchart illustrating the steps of a method for calculating the charging time and equivalent charging rate of a lithium-ion battery according to an embodiment of the present invention is shown.

[0033] like Figure 1 As shown, the calculation methods for the charging time and equivalent charging rate of this lithium-ion battery include: Step 101: Obtain battery information and target operating condition parameters; Step 102: Construct an electro-thermal coupling model based on battery information and target operating condition parameters; Step 103: Simulate the target operating condition using an electro-thermal coupling model to calculate the charging time and equivalent charging rate of the target operating condition.

[0034] In one example, battery information includes battery specific heat capacity, battery mass, 1C current, battery capacity, battery open-circuit voltage, maximum charging rate, and battery internal resistance.

[0035] In one example, the target operating condition parameters include battery heat dissipation area, convective heat transfer coefficient, initial SOC, initial temperature, and cutoff SOC.

[0036] In one example, constructing an electro-thermal coupling model based on battery information and target operating condition parameters includes: Construct electrical and thermal models separately; The coupling between the electrical and thermal models is achieved through parameter transfer. The electrical model transfers current and internal resistance to the thermal model, and the thermal model transfers temperature to the electrical model.

[0037] In one example, the electrical model is:

[0038] In the formula, U is the charging voltage, T is the battery temperature, t is the charging time, U0 is the battery open-circuit voltage, I_1C is the 1C current, C_rate is the maximum charging rate, R is the battery internal resistance, SOC0 is the initial SOC, and Capacity is the battery capacity.

[0039] In one example, the thermal model is:

[0040] Where Cp is the specific heat capacity of the battery, m is the mass of the battery, h is the convective heat transfer coefficient, S is the heat dissipation area of ​​the battery, and T0 is the initial temperature.

[0041] In one example, the target operating condition is simulated using an electro-thermal coupling model to obtain a curve showing the actual charging rate changing over time. The maximum time in the curve is the charging time for calculating the target operating condition.

[0042] In one example, the formula for calculating the equivalent charge rate C_equi is as follows:

[0043] Where C_equi is the equivalent charging rate, This refers to the charging time.

[0044] Specifically, battery information and target operating condition parameters are collected. The necessary parameters for modeling are selected and organized from the battery information provided by the battery supplier. The parameters, units, and descriptions are shown in Table 1.

[0045] Table 1 Battery Parameter Table

[0046] In addition to the battery parameters mentioned above, the normal operation of the model also requires relevant parameters for the target operating conditions. The parameters, units, and descriptions are shown in Table 2.

[0047] Table 2 Target Operating Condition Parameters

[0048] A battery electro-thermal coupling model is constructed. Because the charging ammeter may need to determine the current value based on the voltage, an electrical model is required to predict the charging voltage. The governing equations of the electrical model are as follows:

[0049] In the formula, U is the charging voltage, T is the battery temperature, and t is the charging time.

[0050] The governing equations of the thermal model are as follows:

[0051] The coupling between the electrical and thermal models arises from parameter transfer. The electrical model transfers current and internal resistance to the thermal model, while the thermal model transfers temperature to the electrical model. For parameters that vary, such as charging current, internal resistance, and open-circuit voltage, linear interpolation is used to calculate values ​​at each time step.

[0052] The target operating condition was simulated using an electro-thermal coupling model, yielding the curve of the actual charging rate changing over time. The maximum time t... max That is, charging time. The formula for calculating the equivalent charging rate C_equi is:

[0053] The present invention also provides an electronic device, comprising: a memory storing executable instructions; and a processor executing the executable instructions in the memory to implement the above-described method for calculating the charging time and equivalent charging rate of a lithium-ion battery.

[0054] The present invention also provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the above-described method for calculating the charging time and equivalent charging rate of a lithium-ion battery.

[0055] To facilitate understanding of the solutions and effects of the embodiments of the present invention, five specific application examples are given below. Those skilled in the art should understand that these examples are merely for the purpose of understanding the present invention, and any specific details therein are not intended to limit the present invention in any way.

[0056] Example 1

[0057] Figure 2 A schematic diagram of the open-circuit voltage curve of a ternary-graphite system battery according to Embodiment 1 of the present invention is shown.

[0058] Step 1: Collect battery information and target operating parameters. Information was collected for a specific ternary-graphite semi-solid-state lithium-ion battery. Battery parameters are shown in Tables 3 and 4. Figure 2 As shown.

[0059] Table 3. Parameters of a certain ternary-graphite system battery

[0060] Table 4 Maximum charging rate of a certain ternary-graphite system battery

[0061] In addition to the battery parameters mentioned above, the normal operation of the model also requires relevant parameters for the target operating conditions, as detailed in Table 5.

[0062] Table 5 Target operating parameters of a certain ternary-graphite system battery

[0063] Step 2: Construct the battery electro-thermal coupling model. Since the charging current of a ternary-graphite battery is determined by the voltage, and the battery's internal resistance is constant, the governing equations of the electrical model are as follows:

[0064] In the formula, U is the charging voltage, T is the battery temperature, and t is the charging time.

[0065] The governing equations of the thermal model are as follows:

[0066] The coupling between the electrical and thermal models arises from parameter transfer. The electrical model transfers current and internal resistance to the thermal model, while the thermal model transfers temperature to the electrical model. For variable parameters such as charging current and open-circuit voltage, linear interpolation is used to calculate the values ​​at each time step.

[0067] Step 3: Calculate the charging time and equivalent charging rate under the target operating condition. Simulate the target operating condition using the model built in Step 2 to obtain the curve of the actual charging rate changing with time. The maximum time tmax is the charging time. The formula for calculating the equivalent charging rate C_equi is as follows:

[0068] Figure 3 A schematic diagram of the charging rate variation of a ternary-graphite system battery according to Embodiment 1 of the present invention is shown.

[0069] Figure 4 A schematic diagram showing the charging temperature and voltage variations of a ternary-graphite system battery according to Embodiment 1 of the present invention is shown.

[0070] The calculated charging rate-time curve is as follows: Figure 3 As shown. According to the above definition, the charging time in the 25℃, 10%-80% SOC range is 988s, with an equivalent charging rate of 2.55C. Figure 4 It can be seen that the temperature rise of the battery during charging is close to 25°C, and the relationship between temperature and maximum charging rate is not monotonic. Combined with the influence of SOC on charging current, the final charging rate exhibits a complex variation pattern.

[0071] For comparison, the tested charging time was 970 seconds, with an equivalent charging rate of 2.60C. The calculation error for the charging rate was approximately 2%, and the calculation time was 3 seconds. Therefore, the electro-thermal coupling model can quickly and accurately evaluate the fast-charging performance of batteries.

[0072] Example 2

[0073] Figure 5 A schematic diagram of the open-circuit voltage curve of the lithium iron phosphate-graphite system battery according to Embodiment 2 of the present invention is shown.

[0074] Step 1: Collect battery information and target operating condition parameters. Information was collected for a specific lithium iron phosphate-graphite semi-solid-state lithium-ion battery. Battery parameters are shown in Tables 6-8. Figure 5 As shown.

[0075] Table 6. Parameters of a certain lithium iron phosphate-graphite system battery

[0076] Table 7 Maximum charging rate of a certain lithium iron phosphate-graphite system battery

[0077] Table 8 Internal Resistance of a Certain Lithium Iron Phosphate-Graphite System Battery

[0078] In addition to the battery parameters mentioned above, the normal operation of the model also requires relevant parameters for the target operating conditions, as detailed in Table 9.

[0079] Table 9 Target operating parameters of a certain lithium iron phosphate-graphite system battery

[0080] Step 2: Construct the battery electro-thermal coupling model. Because the charging current of the lithium iron phosphate-graphite system battery is determined by the state of charge (SOC), and the battery's internal resistance is not constant, the governing equations of the electrical model are as follows:

[0081] In the formula, U is the charging voltage, T is the battery temperature, and t is the charging time.

[0082] The governing equations of the thermal model are as follows:

[0083] The coupling between the electrical and thermal models arises from parameter transfer. The electrical model transfers current and internal resistance to the thermal model, while the thermal model transfers temperature to the electrical model. For variable parameters such as charging current, open-circuit voltage, and internal resistance, linear interpolation is used to calculate the values ​​at each time step.

[0084] Step 3: Calculate the charging time and equivalent charging rate under the target operating condition. Simulate the target operating condition using the model built in Step 2 to obtain the curve of the actual charging rate changing with time. The maximum time tmax is the charging time. The formula for calculating the equivalent charging rate C_equi is as follows:

[0085] Figure 6 A schematic diagram of the charging rate variation of the lithium iron phosphate-graphite system battery according to Embodiment 2 of the present invention is shown.

[0086] Figure 7 A schematic diagram showing the charging temperature and voltage variations of a lithium iron phosphate-graphite battery according to Embodiment 2 of the present invention is shown.

[0087] The calculated charging rate-time curve is as follows: Figure 6 As shown. According to the above definition, the charging time in the 10%-80% SOC range at -10℃ is 1612s, with an equivalent charging rate of 1.56C. Figure 7 It can be seen that the battery temperature rise during charging is close to 50°C, which causes the rate of charge to increase with the increase of temperature in the early stage, and decrease with the increase of SOC in the later stage.

[0088] For comparison, the tested charging time was 1546 seconds, with an equivalent charging rate of 1.63C. The calculation error for the charging rate was approximately 5%, and the calculation time was 4 seconds. Therefore, the electro-thermal coupling model can quickly and accurately evaluate the fast-charging performance of batteries.

[0089] Comparative Example 1

[0090] Taking the battery from Example 2 as the analysis object, ignoring temperature changes, the charging time and equivalent charging rate were calculated based on the charging rate corresponding to -10℃ in Table 7. The charging time was 10700s, and the equivalent charging rate was 0.24C. ​​The error in the charging rate was as high as 85%. Therefore, using an electro-thermal coupling model to evaluate the battery's fast-charging performance is more accurate.

[0091] Example 3

[0092] This disclosure provides an electronic device, which includes: a memory storing executable instructions; and a processor that executes the executable instructions in the memory to implement the above-described method for calculating the charging time and equivalent charging rate of a lithium-ion battery.

[0093] An electronic device according to an embodiment of the present disclosure includes a memory and a processor.

[0094] This memory is used to store non-transitory computer-readable instructions. Specifically, the memory may include one or more computer program products, which may include various forms of computer-readable storage media, such as volatile memory and / or non-volatile memory. The volatile memory may, for example, include random access memory (RAM) and / or cache memory. The non-volatile memory may, for example, include read-only memory (ROM), hard disk, flash memory, etc.

[0095] The processor may be a central processing unit (CPU) or other form of processing unit with data processing capabilities and / or instruction execution capabilities, and may control other components in the electronic device to perform desired functions. In one embodiment of this disclosure, the processor is used to execute computer-readable instructions stored in the memory.

[0096] Those skilled in the art will understand that, in order to solve the technical problem of how to achieve a good user experience, this embodiment may also include well-known structures such as communication buses and interfaces, and these well-known structures should also be included within the protection scope of this disclosure.

[0097] For a detailed description of this embodiment, please refer to the corresponding descriptions in the foregoing embodiments, which will not be repeated here.

[0098] Example 4

[0099] This disclosure provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the method for calculating the charging time and equivalent charging rate of a lithium-ion battery.

[0100] A computer-readable storage medium according to embodiments of the present disclosure stores non-transitory computer-readable instructions. When these non-transitory computer-readable instructions are executed by a processor, all or part of the steps of the methods described in the foregoing embodiments of the present disclosure are performed.

[0101] The aforementioned computer-readable storage media include, but are not limited to: optical storage media (e.g., CD-ROM and DVD), magneto-optical storage media (e.g., MO), magnetic storage media (e.g., magnetic tape or portable hard drive), media with built-in rewritable non-volatile memory (e.g., memory card), and media with built-in ROM (e.g., ROM cartridge).

[0102] Those skilled in the art should understand that the above description of the embodiments of the present invention is only intended to illustrate the beneficial effects of the embodiments of the present invention, and is not intended to limit the embodiments of the present invention to any of the examples given.

[0103] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A method for calculating the charging time and equivalent charging rate of a lithium-ion battery, characterized in that, include: Obtain battery information and target operating condition parameters; An electro-thermal coupling model is constructed based on battery information and target operating condition parameters; The target operating condition is simulated using an electro-thermal coupling model, and the charging time and equivalent charging rate under the target operating condition are calculated.

2. The method for calculating the charging time and equivalent charging rate of a lithium-ion battery according to claim 1, wherein, Battery information includes battery specific heat capacity, battery mass, 1C current, battery capacity, battery open circuit voltage, maximum charging rate, and battery internal resistance.

3. The method for calculating the charging time and equivalent charging rate of a lithium-ion battery according to claim 1, wherein, The target operating parameters include battery heat dissipation area, convective heat transfer coefficient, initial SOC, initial temperature, and cutoff SOC.

4. The method for calculating the charging time and equivalent charging rate of a lithium-ion battery according to claim 1, wherein, The electro-thermal coupling model constructed based on battery information and target operating condition parameters includes: Construct electrical and thermal models separately; The coupling between the electrical and thermal models is achieved through parameter transfer. The electrical model transfers current and internal resistance to the thermal model, and the thermal model transfers temperature to the electrical model.

5. The method for calculating the charging time and equivalent charging rate of a lithium-ion battery according to claim 4, wherein, The electric model is: In the formula, U is the charging voltage, T is the battery temperature, t is the charging time, U0 is the battery open-circuit voltage, I_1C is the 1C current, C_rate is the maximum charging rate, R is the battery internal resistance, SOC0 is the initial SOC, and Capacity is the battery capacity.

6. The method for calculating the charging time and equivalent charging rate of a lithium-ion battery according to claim 5, wherein, The thermal model is as follows: Where Cp is the specific heat capacity of the battery, m is the mass of the battery, h is the convective heat transfer coefficient, S is the heat dissipation area of ​​the battery, and T0 is the initial temperature.

7. The method for calculating the charging time and equivalent charging rate of a lithium-ion battery according to claim 1, wherein, The target operating condition is simulated using an electro-thermal coupling model, and the curve of the actual charging rate changing with time is obtained. The maximum time in the curve is the charging time for the calculated target operating condition.

8. The method for calculating the charging time and equivalent charging rate of a lithium-ion battery according to claim 7, wherein, The formula for calculating the equivalent charging rate C_equi is as follows: Where C_equi is the equivalent charging rate, This refers to the charging time.

9. An electronic device, characterized in that, The electronic device includes: Memory, which stores executable instructions; A processor that executes the executable instructions in the memory to implement the method for calculating the charging time and equivalent charging rate of a lithium-ion battery as described in any one of claims 1-8.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by a processor, implements the method for calculating the charging time and equivalent charging rate of the lithium-ion battery as described in any one of claims 1-8.

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