Square battery resistance prediction method and device

Abstract

This application discloses a method and apparatus for predicting the resistance of a prismatic battery. The method includes: acquiring measured resistance data of a card-type battery at different rates and temperatures; wherein the chemical components of the card-type battery and the prismatic battery are connected in parallel; acquiring the relationship between the resistance of the card-type battery and the rate, and the relationship between resistance and temperature; based on the measured resistance data of the card-type battery, the relationship between resistance and rate, and the relationship between resistance and temperature, acquiring the target resistance of the card-type battery at a target rate and a target temperature; and based on the target resistance, the mechanical resistance of the card-type battery, the relationship between the card-type battery and the prismatic battery, and the mechanical resistance of the prismatic battery, obtaining the resistance of the prismatic battery at a target rate and a target temperature. This application aims to solve the technical problem of accurately obtaining the resistance of a prismatic battery at different temperatures and rates.

Description

Technical Field

[0001] This application relates to the field of power battery technology, and in particular to a method and apparatus for predicting the resistance of square batteries. Background Technology

[0002] Lithium-ion batteries, due to their high energy density and good cycle performance, have been applied and commercialized in handheld devices, electronic products, hybrid vehicles, and other fields. Energy storage power stations and electric vehicles exhibit drastic variable current discharge characteristics. Therefore, studying the variation of the internal resistance of lithium-ion power batteries with discharge rate is helpful in improving the accuracy and adaptability of the BMS internal resistance model and enhancing the precision of battery state estimation, which has significant meaning and market value.

[0003] In lithium-ion batteries, DC internal resistance (DCR) is a crucial parameter measuring the sum of ionic and electronic resistance within the battery. It specifically includes ohmic internal resistance, concentration polarization internal resistance, and charge transfer internal resistance. DC internal resistance is a key parameter determining battery power characteristics and also reflects battery aging and consistency between different batteries. Testing DC internal resistance is essential for battery external characteristic modeling and applications. HPPC (Hybrid Pulse Power Characterization) is a technique for evaluating battery pulse power capability and internal resistance, assessing DCR through pulsed current.

[0004] However, the current method of directly using square batteries (square hard-shell lithium-ion batteries) for testing is costly, has limited testing resources, and yields a limited amount of data, making it difficult to accurately obtain the resistance of square batteries at different temperatures and rates. Summary of the Invention

[0005] This application aims to address at least one of the technical problems existing in the prior art. To this end, this application proposes a method and apparatus for predicting the resistance of a square battery, to solve the technical problem of how to accurately obtain the resistance of a square battery under different temperatures and rates.

[0006] In a first aspect, this application provides a method for predicting the resistance of a square battery, the method comprising: Measured resistance data of card batteries at different rates and temperatures were obtained; wherein the chemical components of the card batteries and the chemical components of the square batteries are connected in parallel. Obtain the relationship between the resistance and the rate of increase of the card battery, as well as the relationship between the resistance and the temperature; Based on the measured resistance data of the card battery, the relationship between resistance and rate, and the relationship between resistance and temperature, the target resistance of the card battery at the target rate and target temperature is obtained. Based on the target resistance, the mechanical resistance of the card battery, the relationship between the card battery and the prismatic battery, and the mechanical resistance of the prismatic battery, the target rate and the resistance of the prismatic battery at the target temperature are obtained.

[0007] In at least some embodiments of this application, The process of obtaining the relationship between the resistance and the rate of the card battery includes: obtaining the relationship between the resistance and the rate of the card battery based on the electrode reaction kinetic equation.

[0008] In at least some embodiments of this application, The process of obtaining the relationship between the resistance and temperature of the card battery includes: The relationship between battery reaction rate and temperature was obtained based on the Arrhenius equation. The relationship between battery reaction rate and exchange current density was obtained based on the single-electron first-order reaction of lithium-ion battery deintercalation; Based on the relationship between battery resistance and exchange current density and the relationship between battery reaction rate and exchange current density, the relationship between battery resistance and battery reaction rate is obtained. Based on the relationship between the battery resistance and the battery reaction rate, and the relationship between the battery reaction rate and temperature, the relationship between the battery resistance and temperature is obtained.

[0009] In at least some embodiments of this application, The process of obtaining the target resistance of the card battery at the target rate and target temperature based on the measured resistance data, the relationship between resistance and rate, and the relationship between resistance and temperature includes: Based on the relationship between resistance and rate, the measured resistance data of card batteries with different rates at each temperature are fitted to obtain the fitting relationship between the resistance and rate of the card battery at the corresponding temperature. Based on the fitting relationship between the card battery resistance and the rate at the corresponding temperature and the target rate, the first resistance data of the card battery at different temperatures under the target rate are obtained, wherein the target rate includes a rate greater than that in the measured resistance data of the card battery; Based on the relationship between resistance and temperature, the first resistance data is fitted to obtain the fitting relationship between resistance and temperature of the card battery at the target rate. Based on the fitting relationship between the resistance and temperature of the card battery and the target temperature, the target resistance at the target temperature is obtained.

[0010] In at least some embodiments of this application, The process of obtaining the target resistance of the card battery at the target rate and target temperature based on the measured resistance data, the relationship between resistance and rate, and the relationship between resistance and temperature includes: Based on the relationship between resistance and temperature, the measured resistance data of card batteries at different temperatures under each rate are fitted to obtain the fitting relationship between the resistance and temperature of card batteries at the corresponding rate. Based on the fitting relationship between the card battery resistance and temperature at the corresponding rate and the target temperature, second resistance data of the card battery at different rates are obtained at the target temperature, wherein the target temperature includes temperatures that are greater than or less than the measured resistance data of the card battery. Based on the relationship between resistance and rate, the second resistance data is fitted to obtain the fitting relationship between the resistance and rate of the card battery at the target temperature. Based on the fitting relationship between the resistance and the rate of the card battery and the target rate, the target resistance at the target rate is obtained.

[0011] In at least some embodiments of this application, The process of obtaining the target rate and the resistance of the square battery at the target temperature based on the target resistance, the mechanical resistance of the card battery, the relationship between the card battery and the prismatic battery, and the mechanical resistance of the prismatic battery includes: The chemical resistance of the card battery is obtained based on the difference between the target resistance and the mechanical resistance of the card battery. The chemical resistance of the square battery is obtained based on the ratio of the chemical resistance of the card battery to the diffusion resistance of the card battery and the square battery. Based on the sum of the chemical resistance and the mechanical resistance of the square battery, the target rate and the continuous internal resistance of the square battery at the target temperature are obtained.

[0012] In at least some embodiments of this application, The relationship between the diffusion resistance of the card battery and the square battery includes: The product of the ratio of the area of ​​the square battery electrode to the area of ​​the card battery electrode and the diffusion coefficient; wherein the diffusion coefficient includes the ratio of the porosity of the card battery electrode to the porosity of the square battery electrode, and an exponential term with respect to temperature, discharge rate and SOC.

[0013] In at least some embodiments of this application, The process of obtaining the target rate and the resistance of the square battery at the target temperature based on the target resistance, the mechanical resistance of the card battery, the relationship between the card battery and the prismatic battery, and the mechanical resistance of the prismatic battery includes: The chemical resistance of the card battery is obtained based on the difference between the target resistance and the mechanical resistance of the card battery. The chemical resistance of the square battery is obtained based on the chemical resistance of the card battery and the capacity ratio between the card battery and the square battery. Based on the sum of the chemical resistance and the mechanical resistance of the square battery, the target rate and the instantaneous internal resistance of the square battery at the target temperature are obtained.

[0014] In at least some embodiments of this application, The method further includes: Based on the decomposition test results of the mechanical components of the square battery and the relevant resistance calculation formula, the resistance of the mechanical components of the square battery is obtained; wherein, the mechanical components of the square battery include terminals, adapter plates, and tabs on several electrode plates.

[0015] In a second aspect, this application provides a square battery resistance prediction device, including a memory, one or more processors, and one or more application programs, wherein the one or more application programs are stored in the memory and are configured to, when invoked by the one or more processors, cause the one or more processors to perform the method as described in any one aspect.

[0016] The above-described one or more embodiments of this application have at least one or more of the following beneficial effects: The square battery resistance prediction method provided in this application utilizes the resistance of card batteries and the mechanical resistance of square batteries to eliminate differences in mechanical resistance between batteries, accurately deriving the resistance of square batteries at different temperatures and rates. This alleviates the problem of scarce testing resources for square batteries and reduces costs and risks. Simultaneously, by deriving the relationship between rate and resistance, this application increases the amount of data obtainable through conversion between card and square battery resistance, solving the problem that card batteries cannot directly derive the resistance of square batteries at high rates. By utilizing the relationship between temperature and resistance, and based on measured data or data obtained from rate relationships, the resistance at untested temperatures is derived, reducing the number of temperature points requiring testing, shortening testing time, and improving overall testing efficiency. The more accurate square battery resistance data obtained through this application is beneficial for guiding electrode design, power map improvement, and other related work.

[0017] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0018] The disclosure of this application will become more readily understood with reference to the accompanying drawings. It will be readily understood by those skilled in the art that these drawings are for illustrative purposes only and are not intended to limit the scope of protection of this application. Furthermore, similar numbers in the drawings are used to denote similar components, wherein: Figure 1 This is a schematic diagram of the resistance relationship between a card battery and a square battery in one embodiment of this application; Figure 2 This is a schematic diagram of the internal series and parallel connections of the square battery mechanical components in one embodiment of this application; Figure 3 This is a schematic diagram of the main steps of a square battery resistance prediction method in one embodiment of this application; Figure 4 This is a schematic diagram illustrating the implementation process of a square battery resistance prediction method in one embodiment of this application; Figure 5 This is a schematic diagram of the measured potential of a square battery mechanical component in one embodiment of this application; Figure 6 This is a schematic diagram of the fitting curves of different discharge rates and resistance in one embodiment of this application; Figure 7 This is a schematic diagram of the fitting curves of temperature and resistance under different discharge rates at a 1s discharge time in one embodiment of this application. Figure 8 This is a schematic diagram of the fitting curves of temperature and resistance under different discharge rates for a 10s discharge time in one embodiment of this application. Figure 9 This is a fitting curve between the diffusion resistance of a card battery and a square battery in one embodiment of this application. Detailed Implementation

[0019] Some embodiments of this application are described below with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of this application and are not intended to limit the scope of protection of this application.

[0020] As described in the background section, directly using square batteries for testing is costly, resource-constrained, and makes it difficult to obtain large amounts of data, such as accurately obtaining the resistance at different temperatures and rates. Therefore, this application proposes a method for accurately deriving the resistance of square batteries at different temperatures and rates using the resistance of card-type batteries.

[0021] The applicant's research revealed that converting between the resistance of card batteries and prismatic batteries requires addressing the following issues: First, when analyzing the DC internal resistance of batteries using HPPC testing, the physical impedance of card batteries accounts for a large proportion of the total resistance. This makes them prone to reaching the protection voltage before the set duration of the high-rate pulse current is completed, resulting in a lack of resistance information under high-rate pulse current. Therefore, it is impossible to directly deduce the resistance of prismatic batteries with higher discharge rates. Second, there are significant differences between the mechanical components of card batteries and prismatic batteries. If conversion is performed directly through equivalent circuit relationships, there will be significant discrepancies, making it impossible to accurately measure the resistance of prismatic batteries.

[0022] Based on the above problems, the square battery resistance prediction method proposed in this application overcomes physical differences in the process of deriving the square battery resistance from the resistance data of card batteries. It can not only realize the conversion of resistance at the same rate, but also realize the derivation of resistance at high rate from resistance at low rate; at the same time, it can realize the conversion of resistance between different temperatures, so as to accurately obtain the square battery resistance at different rates and different temperatures.

[0023] Among them, reference Figure 1 This illustrates an example circuit structure for a card-type battery and a prismatic battery. The total resistance of the battery includes the resistance of the mechanical components and the resistance of the chemical components. In a card-type battery, the mechanical components originate from the positive and negative terminals connected in series. The resistance of these mechanical components includes the external tabs and a single ultrasonically welded electrode tab (super-welded tab). In a prismatic battery, the mechanical components also originate from the positive and negative terminals connected in series, but the resistance of the positive / negative mechanical components includes the terminals, adapter plates, and multiple ultrasonically welded electrode tabs (super-welded tabs), and it has a more complex series and parallel connection relationship internally, such as... Figure 2 As shown. Therefore, in the process of solving the resistance of mechanical components, this application does not derive the resistance of the square battery from the mechanical component resistance of the card battery, but directly decomposes and tests the mechanical components of the square battery to obtain the mechanical component resistance of the square battery, and on this basis, obtains the total resistance of the square battery more accurately.

[0024] See appendix Figure 3 , Figure 3 This is a schematic flowchart illustrating the main steps of a square battery resistance prediction method according to an embodiment of this application. Figure 3 As shown, a method for predicting the resistance of a square battery in an embodiment of the present invention mainly includes the following steps S101-S104: S101: Obtain measured resistance data of card batteries at different rates and temperatures; wherein the chemical components of the card batteries are connected in parallel with those of the square batteries; S102: Obtain the relationship between the resistance and the rate of the card battery, as well as the relationship between the resistance and the temperature; S103: Based on the measured resistance data of the card battery, the relationship between resistance and rate, and the relationship between resistance and temperature, obtain the target resistance of the card battery at the target rate and target temperature; S104: Based on the target resistance, the mechanical resistance of the card battery, the relationship between the card battery and the prismatic battery, and the mechanical resistance of the prismatic battery, the target rate and the resistance of the prismatic battery at the target temperature are obtained.

[0025] The resistance of a battery comes from its mechanical and chemical components. In a prismatic battery, the mechanical resistance comes from the positive and negative electrodes connected in series. However, the resistance of the positive / negative mechanical components includes the terminals, adapters, and multiple ultrasonically welded electrode tabs, and has a relatively complex series and parallel connection. In contrast, the resistance of a card battery comes from the positive and negative electrodes connected in series. The resistance of the positive / negative mechanical components includes the external electrode tab and an ultrasonically welded electrode tab. There are significant differences between the two. Therefore, in the process of solving the mechanical resistance, we do not derive it from the mechanical resistance of the card battery. Instead, we directly decompose and test the mechanical components of the prismatic battery, breaking through the traditional thinking of "equivalent circuit derivation" and eliminating the systematic errors caused by the structural differences between the mechanical components of the card battery and the prismatic battery.

[0026] The resistance of chemical components is understandable; please refer to [reference]. Figure 1 The chemical components of a card battery include a positive electrode, a separator, and a negative electrode connected in series; while the chemical components of a prismatic battery include multiple positive electrodes, separators, and negative electrodes connected in parallel. Each positive electrode, separator, and negative electrode is the same as the chemical components of the card battery, connected in series. In other words, the chemical components of the card battery and the prismatic battery are connected in parallel, thus allowing the resistance of the prismatic battery to be predicted from the resistance of the card battery.

[0027] Based on the above settings, due to the high internal resistance of card batteries, resistance information at high rates cannot be directly obtained during card battery testing. Therefore, this application derives the relationship between rate and resistance based on measured resistance data of card batteries at different rates and temperatures, thereby increasing the amount of data obtainable through the conversion between card battery and prismatic battery resistance. Simultaneously, utilizing the relationship between temperature and resistance, the resistance at untested temperatures is derived from existing test temperatures, obtaining the resistance at the target temperature, which serves as the basis for converting to obtain the prismatic battery resistance. Using the obtained relationships between resistance and rate, and resistance and temperature, the target resistance of the card battery at the target rate and target temperature can be obtained. The target rate and target temperature are also the target rate and target temperature of the prismatic battery to be derived. The target resistance of the card battery can be understood as the total resistance of the card battery. Based on the total resistance and mechanical component resistance of the card battery, the chemical component resistance of the card battery can be obtained. Since there is a certain relationship between the chemical components of the card battery and the prismatic battery, the mechanical component resistance of the prismatic battery at the corresponding rate and temperature can be calculated from the chemical component resistance of the card battery. Based on the obtained chemical resistance of the square battery and the measured mechanical resistance, the target rate and total resistance of the square battery at the target temperature are finally obtained.

[0028] The embodiments of this application utilize the resistance of card batteries and the mechanical resistance of prismatic batteries to eliminate the differences in mechanical resistance between batteries, accurately deriving the resistance of prismatic batteries at different temperatures and rates. This alleviates the problem of scarce testing resources for prismatic batteries and reduces costs and risks. Simultaneously, by deriving the relationship between rate and resistance, this application increases the amount of data obtainable through conversion between card and prismatic battery resistance, facilitating the establishment of a data model for prismatic battery resistance and solving the problem that card batteries cannot directly derive the resistance of prismatic batteries at high rates. By utilizing the relationship between temperature and resistance, and based on measured data or data obtained from rate relationships, the resistance at untested temperatures is derived, reducing the number of temperature points requiring testing, shortening testing time, and improving overall testing efficiency. The more accurate prismatic battery resistance data obtained through this application is beneficial for guiding electrode design, power map improvement, and other related work.

[0029] In one embodiment, the relationship between the resistance and the rate of the card battery is obtained: the relationship between the resistance and the rate of the card battery is obtained based on the electrode reaction kinetic equation.

[0030] Specifically, the resistance at higher rate pulse currents is derived based on HPPC test data (at 0.1C, 0.8C, 1.0C, 1.2C, and 2.0C rate pulse currents) for card batteries. The principle is as follows: HPPC testing simulates the transient response of the battery under dynamic conditions such as start-stop, acceleration, and hill climbing by applying short-duration, high-amplitude current pulses, thereby quantifying the battery's DC internal resistance and polarization effect.

[0031] Resistance calculation formula: Internal resistance: R = ΔV / I pulse Where ΔV is the voltage drop during the pulse, and I pulse This represents the amplitude of the pulse current. Based on the Butler-Volmer equation describing electrode reaction kinetics in the field of electrochemistry, combined with actual test data, the resistance-rate relationship formula is simplified as follows: (1) in, a , b , d For coefficients, C For testing the magnification ratio.

[0032] In this way, low-rate (0.1C-2C) data can be used to predict high-rate (10C+) resistance, solving the industry pain point that card batteries cannot be tested at high rates due to their high internal resistance, realizing rate extrapolation, filling data gaps, and covering data under extreme working conditions.

[0033] In one embodiment, the coefficients in the formula can be determined through multiple experimental data, thereby determining the relationship between resistance and multiplier.

[0034] In one embodiment, obtaining the relationship between the resistance and temperature of the card battery specifically includes steps S201-S204: S201: The relationship between battery reaction rate and temperature is obtained based on the Arrhenius equation; The Arrhenius equation shows that the reaction rate constant has an exponential relationship with temperature. Increasing the temperature leads to more reactant molecules reaching or exceeding the activation energy, thus accelerating the reaction rate. The equation is shown below: (2) Where k is the reaction rate constant; A is a constant; E a It is the activation energy, kJ / mol; R It is the molar gas constant, J / (mol•K); T It is absolute temperature, K.

[0035] S202: The relationship between battery reaction rate and exchange current density is obtained based on the single-electron first-order reaction of lithium-ion battery deintercalation; There is a correlation between the reaction rate constant and the battery resistance for single-electron first-order reactions involving insertion and extraction in lithium-ion batteries: (3) in, It is the exchange current density; n It is the number of electrons transferred; k It is the reaction rate constant, in m / s; c It is the reactant concentration, mol / m 3 ; F It is Faraday's constant.

[0036] S203: Based on the relationship between battery resistance and exchange current density and the relationship between battery reaction rate and exchange current density, the relationship between battery resistance and battery reaction rate is obtained. The relationship between battery resistance and exchange current density: (4) in, i 0 The exchange current density is the same as in formula (3). The consistency represents the exchange current density of the card battery, A / m. 2 ; R ct It is the charge transport resistor; Using formula (3) i 0 Substituting into formula (4), we get: (5) Charge transport resistance R ct With reaction rate constant k They are inversely proportional. This means that the larger the reaction rate constant, the smaller the charge transport resistance of the battery, and the better the electrochemical performance of the battery.

[0037] S204: Based on the relationship between battery resistance and battery reaction rate, and the relationship between battery reaction rate and temperature, the relationship between battery resistance and temperature is obtained.

[0038] Specifically, according to formula (2), the reaction rate constant Substituting into formula (5), we get: Taking the natural logarithm, we get: Further simplification yields: (6) in, , is a constant.

[0039] At the extreme temperature, It becomes negligible, therefore, it can be approximated by (6): Therefore, resistance R ct With temperature T The relationship between them can be represented as: (7) Where B and C are constants, ; The constants in the formula are determined by experimental data.

[0040] In this way, resistance at low and high temperatures can be predicted using data from normal temperatures, i.e., resistance across the entire temperature range can be predicted, temperature extrapolation can be achieved, the number of temperature point tests can be reduced, and testing efficiency can be improved.

[0041] In one embodiment, one method for calculating the target resistance of a card battery at a target rate and a target temperature is: first calculate the resistance at different temperatures within the target rate, and then calculate the resistance at the target temperature. Specifically: Based on the relationship between resistance and rate, the measured resistance data of card batteries with different rates at each temperature are fitted to obtain the fitting relationship between the resistance and rate of the card battery at the corresponding temperature; that is, by substituting the measured resistance data of different rates at each temperature into formula (1) for fitting, the fitting relationship between the resistance and rate of the card battery at the corresponding temperature can be obtained. This can be understood as follows: at each temperature, in formula (1)... a , b , d Different specific values ​​result in different fitting relationships. By using multiple sets of measured data, the relationship between the resistance and the rate of the card battery at different temperatures can be obtained. Based on the fitting relationship between the card battery resistance and the rate of increase at the corresponding temperature and the target rate of increase, the first resistance data of the card battery at different temperatures under the target rate of increase is obtained. The target rate of increase includes a rate of increase greater than the measured resistance data of the card battery. This step determines the required target rate of increase. Substituting the target rate of increase into the determined fitting relationship between the card battery resistance and the rate of increase at different temperatures yields multiple sets of resistance data corresponding to the target rate of increase at different temperatures. These sets of data are used as the first resistance data. It should be understood that the target rate of increase can be greater than the rate of increase in the measured resistance data, and can be directly obtained through the determined fitting relationship between the card battery resistance and the rate of increase. Based on the relationship between resistance and temperature, the first resistance data is fitted to obtain the fitting relationship between the resistance and temperature of the card battery at the target rate: By knowing multiple different temperatures and corresponding first resistance data in the previous step, the temperature and corresponding first resistance data are substituted into formula (7) for fitting, and the constants B and C in formula (7) can be determined, thereby obtaining the fitting relationship between the resistance and temperature of the card battery. Based on the fitting relationship between the resistance and temperature of the card battery and the target temperature, the target resistance at the target temperature is obtained. That is, by substituting the target temperature into the formula (7) that determines the constant, the target resistance at the target temperature can be obtained.

[0042] In one embodiment, another method for calculating the target resistance of a card battery at a target rate and target temperature is to first calculate the resistance at the target temperature, and then calculate the resistance at the target rate. Specifically: Based on the relationship between resistance and temperature, the measured resistance data of card batteries at different temperatures under each multiplier are fitted to obtain the fitting relationship between the resistance and temperature of the card battery at the corresponding multiplier (preset value); that is, by using the relationship of formula (7), the measured resistance data of different temperatures under each multiplier are substituted into formula (7) for fitting, and the fitting relationship between the resistance and temperature of the card battery at the corresponding multiplier can be obtained. It can be understood that the specific values ​​of constants B and C in formula (7) are different under each multiplier, and the corresponding fitting relationship is also different. Through multiple sets of measured data, the relationship between the resistance and temperature of the card battery under different multipliers can be obtained. Based on the fitted relationship between the card battery resistance and temperature at the corresponding rate and the target temperature, second resistance data for different rates are obtained at the target temperature of the card battery. The target temperature includes temperatures greater than or less than the measured resistance data of the card battery. This step determines the required target temperature and substitutes it into the established fitted relationship between the card battery resistance and temperature at different rates. This yields multiple sets of resistance data corresponding to the target temperature at different rates, which are then used as the second resistance data. It should be understood that the target temperature can be greater than or less than the temperature in the measured resistance data, and can be directly obtained through the established fitted relationship between the card battery resistance and temperature. Based on the relationship between resistance and rate of performance, the second resistance data is fitted to obtain the fitting relationship between the resistance and rate of the card battery at the target temperature. Using the known second resistance data from the previous step, the rate of performance and the corresponding second resistance data are substituted into formula (1) for fitting, thus determining the constant in formula (1). a , b , d Thus, the fitting relationship between the resistance and the rate of the card battery is obtained; Based on the fitting relationship between the resistance and the rate of the card battery and the target rate, the target resistance at the target rate is obtained. That is, by substituting the target rate into the formula (1) for determining the constant, the target resistance at the target rate can be obtained.

[0043] In this way, resistance data under all operating conditions can be extrapolated through the conversion model between resistance and dimensions such as magnification and temperature, saving testing costs.

[0044] In one embodiment, based on Figure 1 and Figure 2It is known that the chemical components of card batteries and prismatic batteries are connected in parallel. The key to deriving prismatic batteries from card batteries lies in the relationship between them, namely, determining the number of parallel connections (N). Without considering diffusion, N can be obtained through capacity ratio or area ratio. However, considering the different spatial distributions of card and prismatic batteries within the battery, parallel connections based on capacity ratio or area ratio are not feasible in the liquid phase diffusion region. Therefore, further research on the parallel connection relationship is needed.

[0045] The applicant's research found that diffusion resistance is related to the porosity of the electrode, the area of ​​the electrode, the magnitude of the applied current, temperature, and the state of charge (SOC) of the battery. The objective of this application is to determine the relationship between the diffusion resistance of card batteries and prismatic batteries; therefore, a calculation formula is proposed: (8) in, K The coefficient relating the diffusion resistance of card batteries and square batteries; A This represents the area of ​​the electrode plates in the battery; ε The porosity of the electrode sheet; C This refers to the charge / discharge rate; T For temperature.

[0046] The relationship coefficient between the diffusion resistance of card batteries and square batteries K It is derived based on the coupling relationship between electrochemical diffusion kinetics and battery geometry / material parameters. The card electrode uses the same material as the square electrode, differing only in geometry and porosity. A 方形 / A 卡片 This represents the ratio of the areas of the two types of battery electrodes, which directly affects the ion diffusion path. Ideally... A 方形 / A 卡片 It can directly reflect the coefficient between the card and the square diffusion resistor. K However, due to the different forces and internal structures of card batteries and prismatic batteries, it is necessary to... A 方形 / A 卡片 Corrections are needed. The diffusion coefficient is affected by porosity. ε The porosity is used to represent the diffusion coefficient, but in this experiment, porosity is also affected by temperature, discharge rate, and SOC. Therefore, it is necessary to... C , T SOC is introduced through an exponential term. ε Make corrections and simplify to 1.5× C ^ 0.5× T ^ (1 / 10)×e^ The form is (0.2 × SOC). Where e ^ (0.2×SOC) is used to describe E a It increases with increasing SOC, and here we assume that the effect of SOC on activation energy is a linear approximation. T ^ (1 / 10) reflects the weak dependence of the diffusion coefficient on temperature. C ^ The value 0.5 describes the phenomenon that high-rate diffusion exacerbates concentration polarization and increases diffusion resistance. This formula combines empirical models with theoretical derivations, quantifying the difference in diffusion resistance of the battery through geometric proportions and key parameters of diffusion kinetics (porosity, rate, temperature, and state of charge). The accuracy of the parameter exponents is verified experimentally.

[0047] Thus, by proposing a quaternary coupled model of porosity-ratio-temperature-SOC, a dynamic porosity correction coefficient is established. K ,in C ^ 0.5 reflects the decrease in porosity utilization caused by concentration polarization at high magnification. T ^ (1 / 10) Capturing the weak dependence of temperature on the electrolyte diffusion coefficient (ignored by traditional models), e ^ (0.2×SOC) Quantifies the nonlinear effect of SOC on activation energy. K It is a dynamic value (changing with temperature, rate, and SOC), turning the static ratio into a dynamic function. It can establish chemical component models for card batteries and prismatic batteries, and can also reverse-engineer high-rate and full-temperature ranges through low-rate and narrow-temperature ranges, achieving accurate mapping of diffusion resistance under all operating conditions.

[0048] In one possible implementation, based on the aforementioned relationship between the resistance of the card battery and the square battery, the resistance of the card battery can be used as (card battery resistance - card battery mechanical component resistance) / K By calculating the resistance of the square battery's mechanical components, we can obtain the target rate and the continuous internal resistance of the square battery at the target temperature (10s internal resistance, corresponding to continuous acceleration and thermal management calculations). The card battery resistance is based on the target resistance obtained at the target temperature and target rate in the above embodiment. (Card battery resistance - Card battery mechanical component resistance) / K This can be understood as obtaining the chemical resistance of a square battery.

[0049] In one possible implementation, based on the relationship between the resistances of the card battery and the prismatic battery described above, the target rate and the instantaneous internal resistance (1-second internal resistance, corresponding to cold start and peak power) of the prismatic battery at the target temperature can be obtained by using (card battery resistance - card battery mechanical component resistance) / N + prismatic battery mechanical component resistance. Here, N is the capacity ratio, which can be obtained from the known capacities of the card battery and the prismatic battery, and will not be elaborated here. The instantaneous internal resistance is almost a pure ohmic resistance, and its diffusion effect is not significant. Therefore, using the simpler "capacity ratio" to scale the chemical component resistance greatly simplifies the calculation and improves efficiency while ensuring accuracy. The card battery resistance is the target resistance at the target temperature and target rate obtained in the above implementation. (card battery resistance - card battery mechanical component resistance) / N can be understood as obtaining the chemical component resistance of the prismatic battery.

[0050] By separately calculating the continuous internal resistance and the instantaneous internal resistance, the transfer of ohmic resistance is achieved through the capacitance ratio. K The value is converted to achieve diffusion resistance, so as to completely decouple the ohmic information and diffusion information through time division, avoid the mixing of mechanical parts, ohms and diffusion, and greatly reduce the overall error. In one embodiment, since the continuous internal resistance comprises ohmic resistance + charge transfer resistance + diffusion resistance, with diffusion resistance accounting for the majority and a small amount of charge transfer resistance mixed in, it has been incorporated into empirical analysis. K The same correction is applied to the value without further splitting, thus balancing testing efficiency and accuracy requirements. The instantaneous internal resistance mainly includes ohmic resistance, so the diffusion resistance can be obtained by subtracting the instantaneous internal resistance from the continuous internal resistance, as shown in Table 5 below. At this point, the accuracy can be further improved by calculating the diffusion resistance. Specifically, when calculating the instantaneous internal resistance of the square battery, use (card battery resistance - card battery mechanical component resistance) / N + square battery mechanical component resistance. The card battery's internal resistance is the 1s internal resistance, i.e., the instantaneous internal resistance of the card battery. When calculating the continuous internal resistance of the square battery, first calculate the diffusion resistance of the square battery, using the card battery's internal resistance as the 10s internal resistance minus the 1s internal resistance, (card battery resistance - card battery mechanical component resistance) / K Determine the diffusion resistance of the square battery, then add the diffusion resistance to the instantaneous internal resistance of the square battery to obtain the continuous internal resistance of the square battery. This can be calculated using (cell battery resistance - cell battery mechanical component resistance) / K The instantaneous internal resistance of a square battery allows us to obtain the target rate of operation and the continuous resistance of the square battery at the target temperature. Because... K The value is only valid for diffusion resistance. Introducing the 1s internal resistance introduces a certain structural scale error, causing the ohmic resistance to be excessively reduced. The 10s calculation will be systematically underestimated, and since there is no diffusion resistance in the 1s internal resistance, using... KThe value of the value will actually amplify the error. Therefore, by treating the ohmic resistance and the diffusion resistance independently, the prediction accuracy can be further improved.

[0051] Based on the above implementation methods, refer to Figure 4 One possible implementation of a square battery resistance prediction method according to an embodiment of this application is as follows: Obtain the measured resistance data R0 of the card battery at different rates and temperatures; The relationship between the resistance of the card battery and the multiplier is obtained, and the relationship formula (1) is obtained. The resistance R1 at the target multiplier is obtained through the relationship formula (1). The relationship between the resistance of the card battery and temperature is obtained, and the relationship formula (7) is obtained. The resistance R1 is substituted into the formula (7) to obtain the resistance R2 at the target temperature. Let resistor R2 be the target resistance of the card battery, based on ((card battery resistance - card battery mechanical component resistance) / ... K +resistance of the mechanical components of the square battery), to obtain the resistance R of the square battery at the target temperature and target rate. e .

[0052] Alternatively, resistor R2 can be obtained first through formula (7), and then R1 can be obtained by substituting resistor R2 into formula (1).

[0053] The following example will illustrate a method for predicting the resistance of a square battery.

[0054] 1) Resistance test of mechanical components of square batteries: For the solder joints and adapter pieces, a resistance meter was used for testing. One end of the meter was in contact with the top cover terminal, and the other end was used to measure the resistance of each part of the top cover. Figure 5 As shown, the specific measured data of each mechanical component on electrode 600 are shown in Table 1. The electrode post 100 and electrode tab 200 utilize... calculate; L , A Obtained through design parameters. ρ The resistivity of the corresponding material.

[0055] Table 1: Table 2 below shows the resistance values ​​of each part obtained from the disassembly of the mechanical components of the square battery. Specifically, the resistance value of laser-welded stamp 300 is obtained by subtracting the calculated value of terminal 100 from the measured value at point 1; the resistance value of adapter 400 is obtained by subtracting the measured value at point 1 from the measured value at point 2; and the resistance value of ultrasonic-welded stamp 500 is obtained by subtracting the measured value at point 2 from the measured value at point 3.

[0056] Table 2: 2) Predicting the resistance of a square battery using a card-type battery: To predict the resistance of a prismatic battery using the resistance of a card battery, the card battery resistance must first be converted to the resistance of a prismatic battery at the same temperature and discharge rate (based on the relationship between resistance and discharge rate, and the conversion process between resistance and temperature in the prediction method described above). The resistance corresponding to a 1-second discharge time is assumed to have no diffusion resistance; this part of the resistance conversion uses the capacity ratio as the parallel connection number. Simultaneously, the internal resistance of the 1-second discharge also corresponds to cold start and peak power. The derivation of the prismatic battery resistance in 1 second is calculated using the following formula: (Card battery resistance - Card battery mechanical component resistance) / Capacity ratio + Prismatic battery mechanical component resistance = Prismatic battery resistance (1 second). The capacity of the prismatic battery is 70.6 Ah, and the capacity ratio in this formula is 1765.

[0057] The resistance corresponding to a 10-second discharge time includes diffusion resistance, and the internal resistance during the 10-second discharge also corresponds to continuous acceleration and thermal management calculations. To investigate the relationship of diffusion resistance, a relationship between the diffusion resistance of card batteries and prismatic batteries is established, using the formula (card battery resistance - card battery mechanical component resistance) / K + Resistance of mechanical parts of square battery = Resistance of square battery (10s) Calculate the resistance of square battery. K The calculations are performed according to the above formula (8), as shown in Table 3, which shows the coefficients of the diffusion resistance of the card and the square battery at different temperatures. K .

[0058] Table 3: Table 4 shows the resistance of the square battery after discharging for 1 second and 10 seconds at different discharge rates and temperatures.

[0059] Table 4: Table 5 shows the resistance after subtracting 1 second from the discharge time at different 1C discharge rates. The resistance of the battery at 40℃ and -20℃ is calculated using the resistance-temperature relationship (Formula (7)).

[0060] Table 5: The calculation results for deriving the resistance of a square battery from the resistance of a card-type battery are shown in Table 6. The calculation errors are shown in Table 7. As can be seen from Table 7, the proposed solution accurately derives the resistance of a square battery from the resistance of a card-type battery. This alleviates the shortage of testing resources for square batteries on the one hand, and reduces testing costs by using card-type batteries instead of square batteries on the other.

[0061] Table 6: Table 7: 3) Calculation of the resistance of the card battery at different ratios: (1) At room temperature, a standard capacity 40mAh card battery with a state of charge (SOC) of 50% was subjected to HPPC testing at discharge rates of 0.1C, 0.8C, 1.0C, 1.2C, and 2.0C for 30 seconds. The battery was charged at a 0.1C rate to restore its SOC to 50% before each discharge. After each charge / discharge, the battery was allowed to rest for 20 minutes to allow it to return to equilibrium. Figure 6 As shown.

[0062] (2) Calculate the card resistance at discharge rates of 0.1C, 0.8C, 1.0C, and 1.2C based on the voltage difference observed when the card battery discharges for 10 seconds. ,like Figure 6 As shown in Table 8. Table 8 shows the voltage difference and resistance values ​​at different magnification rates. Using... That is, the formula (1) fits the resistance at discharge rates of 0.1C, 0.8C, 1.0C, and 1.2C. The fitting results are as follows Figure 7 As shown, the fitting formula is obtained. .

[0063] Table 8: (3) Calculate the resistance at a 2.0C rate (preset as the target rate) and substitute it into the above fitting formula. The calculated resistance was 2.3269Ω. Compared with the measured resistance value at a discharge rate of 2.0C, the error of the calculated value was 2.09% (error = (calculated value - measured value) / measured value), and the specific values ​​are shown in Table 9.

[0064] Table 9: It should be understood that through the above steps (1) and (2), the fitting formula of the multiplier and resistance at the preset test temperature can be obtained. Based on the obtained formula, the resistance corresponding to any multiplier at the same temperature can be obtained, that is, the resistance R1 in the above implementation process.

[0065] 4) Calculation of the resistance of the card battery at different temperatures: The resistance of the card battery was obtained by HPPC testing at -10℃, 0℃, 25℃, and 45℃. Specific data are shown in Table 10. A graph of the logarithm of the resistance versus the reciprocal of the temperature is shown below. Figure 8 and Figure 9 As shown.

[0066] Table 10: Fitting is performed according to formula (7). Under the same discharge rate, the constant of formula (7) is determined to obtain the temperature and resistance curve at a certain discharge rate. Thus, the temperature and resistance relationship curves at different discharge rates are obtained. The resistance values ​​at -20℃ and 40℃ under different discharge rates can be solved by the curves, as shown in Table 11.

[0067] Table 11: It's important to understand that by calculating the resistance of the card battery at different temperatures as described above, a fitting formula or curve for temperature and resistance at a preset rate can be obtained. Based on this formula or curve, the resistance at any temperature under the same rate can be calculated, which is the resistance R2 in the above implementation process. This method comprehensively considers the influence of temperature on reaction rate, ion diffusion, and other factors, and is applicable to prediction over a wide temperature range.

[0068] Furthermore, the processes 3) and 4) above can be used alternately, that is, R2 can be solved through R1, or R1 can be solved through R2.

[0069] Specifically, R1 is solved by R2: for each multiplier, a formula (7) with a definite constant is fitted, and the resistance value R2 at different temperatures under the same multiplier can be determined (a temperature-resistance relationship curve can be obtained for each row in Table 10). Thus, the resistance R2 corresponding to different multipliers at unknown temperatures can be obtained through the data of each row. Then, based on the resistance corresponding to different multipliers at unknown temperatures, the definite relationship between the multiplier and resistance at the unknown temperature can be obtained by fitting, that is, the formula (1) with a definite constant can be obtained. Thus, the resistance R1 corresponding to any multiplier at the unknown temperature can be obtained.

[0070] For example, referring to Table 10, each row of the 0.1C, 0.8C, 1.0C, and 1.2C multipliers corresponds to a formula (7) for a definite constant. Based on the different formulas (7) for each row, the resistance values ​​corresponding to 0.1C, 0.8C, 1.0C, and 1.2C at -20℃ and 40℃ temperatures can be obtained in Table 11. Based on the resistance values ​​corresponding to 0.1C, 0.8C, 1.0C, and 1.2C at -20℃ or 40℃ temperatures, a formula (1) for a definite constant can be fitted. Substituting this formula (1) into the target multiplier 2C, the resistance corresponding to 2C at -20℃ or 40℃ temperatures can be obtained (the last row in Table 11).

[0071] Specifically, R2 is solved by R1: using multiple formulas (1) at different temperatures, the relationship between the constant and the resistance at the corresponding temperature can be obtained (a certain fitting relationship between the constant and the resistance can be obtained for each column in Table 10), so that multiple resistance values ​​R1 corresponding to the target multiple at different temperatures can be obtained, and the constant of formula (7) under the target multiple can be solved. Then, by substituting the unknown different temperatures, the resistance R2 at different temperatures can be obtained.

[0072] For example, referring to Table 10, each column of temperatures -10℃, 0℃, 25℃, and 45℃ corresponds to the resistance corresponding to different multipliers of 0.1C, 0.8C, 1.0C, and 1.2C. Therefore, for each column, the multiplier and resistance relationship with a fixed constant at the corresponding temperature can be obtained. For example, the resistances corresponding to 0.1C, 0.8C, 1.0C, and 1.2C at -10℃ can be determined by fitting the formula (1) to obtain the constant of formula (1) and the multiplier and resistance relationship corresponding to -10℃. Based on this relationship, 2C can be substituted to obtain the resistance corresponding to the 2C multiplier. Similarly, the resistances corresponding to the 2C multiplier at 0℃, 25℃, and 45℃ can be calculated in turn (the last row in Table 10). Then, substitute the resistance values ​​corresponding to different temperatures at the 2C rate into formula (7) to fit and obtain formula (7) with a definite constant, thereby obtaining the temperature and resistance relationship corresponding to the 2C rate. Finally, substitute the target temperature of -20℃ or 40℃ into the obtained temperature and resistance relationship to obtain the resistance corresponding to -20℃ or 40℃ at the 2C rate (last row in Table 11).

[0073] It should be noted that although the steps in the above embodiments are described in a specific order, those skilled in the art will understand that in order to achieve the effects of the present invention, different steps do not necessarily have to be executed in such an order. They can be executed simultaneously (in parallel) or in other orders, and these variations are all within the scope of protection of the present invention.

[0074] Furthermore, the present invention also provides a square battery resistance prediction device, including a memory, one or more processors, and one or more application programs, wherein the one or more application programs are stored in the memory, and the one or more application programs are configured to, when invoked by the one or more processors, cause the one or more processors to perform the method described in any of the preceding technical solutions.

[0075] The apparatus in this embodiment of the invention mainly includes a memory and a processor. The memory can be configured to store a program for executing the methods of the above-described method embodiments, and the processor can be configured to execute the program in the memory. This program includes, but is not limited to, a program for executing the methods of the above-described method embodiments. For ease of explanation, only the parts related to the embodiments of the invention are shown; for specific technical details not disclosed, please refer to the method section of the embodiments of the invention.

[0076] In embodiments of the present invention, the apparatus may be a control device comprising various electronic components. In some possible implementations, the electronic device may include multiple storage devices and multiple processors. The program executing the methods of the above method embodiments may be divided into multiple subroutines, each subroutine being loaded and run by a processor to perform different steps of the methods of the above method embodiments. Specifically, each subroutine may be stored in a different memory, and each processor may be configured to execute programs in one or more memories to jointly implement the methods of the above method embodiments; that is, each processor executes different steps of the methods of the above method embodiments to jointly implement the methods of the above method embodiments.

[0077] The above-mentioned device is used for performing Figure 3 The method embodiments shown are similar in technical principle, technical problem solved and technical effect produced. Those skilled in the art can clearly understand that, for the sake of convenience and brevity, the specific working process of the electronic device and related descriptions can be referred to the content described in the method embodiments, and will not be repeated here.

[0078] Those skilled in the art will understand that all or part of the processes in the method of the above embodiment of the present invention can also be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable file, or some intermediate form. The computer-readable storage medium can include any entity or device capable of carrying the computer program code, a medium, a USB flash drive, a portable hard drive, a magnetic disk, an optical disk, a computer memory, a read-only memory, a random access memory, an electrical carrier signal, a telecommunication signal, and a software distribution medium, etc. It should be noted that the content included in the computer-readable storage medium can be appropriately added or removed according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, the computer-readable storage medium does not include electrical carrier signals and telecommunication signals.

[0079] Furthermore, the present invention also provides a computer-readable storage medium. In one embodiment of the computer-readable storage medium according to the present invention, the computer-readable storage medium can be configured to store a program that performs the above-described method embodiments, the program of which can be loaded and run by a processor to implement the above-described methods. For ease of explanation, only the parts related to the embodiments of the present invention are shown; for specific technical details not disclosed, please refer to the method section of the embodiments of the present invention. The computer-readable storage medium can be a storage device comprising various electronic devices. Optionally, in the embodiments of the present invention, the computer-readable storage medium is a non-transitory computer-readable storage medium.

[0080] Furthermore, it should be understood that the various modules are merely illustrative of the functional modules of the device of the present invention. The physical devices corresponding to these modules may be the processor itself, or a part of the processor's software, hardware, or a combination of software and hardware. Therefore, the number of modules shown in the figures is merely schematic. Those skilled in the art will understand that the various modules in the system can be adaptively split or merged. Such splitting or merging of specific modules will not cause the technical solution to deviate from the principles of the present invention; therefore, the technical solutions after splitting or merging will fall within the protection scope of the present invention.

[0081] It should be understood that various parts of the present invention can be implemented in hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented in software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0082] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0083] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

[0084] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A method for predicting the resistance of a square battery, characterized in that, The method includes: Measured resistance data of card batteries at different rates and temperatures were obtained; wherein the chemical components of the card batteries and the chemical components of the square batteries are connected in parallel. Obtain the relationship between the resistance and the rate of increase of the card battery, as well as the relationship between the resistance and the temperature; Based on the measured resistance data of the card battery, the relationship between resistance and rate, and the relationship between resistance and temperature, the target resistance of the card battery at the target rate and target temperature is obtained. Based on the target resistance, the mechanical resistance of the card battery, the relationship between the card battery and the prismatic battery, and the mechanical resistance of the prismatic battery, the target rate and the resistance of the prismatic battery at the target temperature are obtained, including: The chemical resistance of the card battery is obtained based on the difference between the target resistance and the mechanical resistance of the card battery. The chemical resistance of the square battery is obtained based on the ratio of the chemical resistance of the card battery to the diffusion resistance of the card battery and the square battery. Based on the sum of the chemical resistance and the mechanical resistance of the square battery, the target rate and the continuous internal resistance of the square battery at the target temperature are obtained. The chemical resistance of the square battery is obtained based on the chemical resistance of the card battery and the capacity ratio between the card battery and the square battery. Based on the sum of the chemical resistance and the mechanical resistance of the square battery, the target rate and the instantaneous internal resistance of the square battery at the target temperature are obtained.

2. The method for predicting the resistance of a square battery according to claim 1, characterized in that, The process of obtaining the relationship between the resistance and the rate of the card battery includes: obtaining the relationship between the resistance and the rate of the card battery based on the electrode reaction kinetic equation.

3. The method for predicting the resistance of a square battery according to claim 1, characterized in that, The process of obtaining the relationship between the resistance and temperature of the card battery includes: The relationship between battery reaction rate and temperature was obtained based on the Arrhenius equation. The relationship between battery reaction rate and exchange current density was obtained based on the single-electron first-order reaction of lithium-ion battery deintercalation; Based on the relationship between battery resistance and exchange current density and the relationship between battery reaction rate and exchange current density, the relationship between battery resistance and battery reaction rate is obtained. Based on the relationship between the battery resistance and the battery reaction rate, and the relationship between the battery reaction rate and temperature, the relationship between the battery resistance and temperature is obtained.

4. The method for predicting the resistance of a square battery according to claim 1, characterized in that, The process of obtaining the target resistance of the card battery at the target rate and target temperature based on the measured resistance data, the relationship between resistance and rate, and the relationship between resistance and temperature includes: Based on the relationship between resistance and rate, the measured resistance data of card batteries with different rates at each temperature are fitted to obtain the fitting relationship between the resistance and rate of the card battery at the corresponding temperature. Based on the fitting relationship between the card battery resistance and the rate at the corresponding temperature and the target rate, the first resistance data of the card battery at different temperatures under the target rate are obtained, wherein the target rate includes a rate greater than that in the measured resistance data of the card battery; Based on the relationship between resistance and temperature, the first resistance data is fitted to obtain the fitting relationship between resistance and temperature of the card battery at the target rate. Based on the fitting relationship between the resistance and temperature of the card battery and the target temperature, the target resistance at the target temperature is obtained.

5. The method for predicting the resistance of a square battery according to claim 1, characterized in that, The process of obtaining the target resistance of the card battery at the target rate and target temperature based on the measured resistance data, the relationship between resistance and rate, and the relationship between resistance and temperature includes: Based on the relationship between resistance and temperature, the measured resistance data of card batteries at different temperatures under each rate are fitted to obtain the fitting relationship between the resistance and temperature of card batteries at the corresponding rate. Based on the fitting relationship between the resistance and temperature of the card battery at the corresponding rate and the target temperature, second resistance data of the card battery at different rates at the target temperature are obtained, wherein the target temperature includes temperatures that are greater than or less than the measured resistance data of the card battery. Based on the relationship between resistance and rate, the second resistance data is fitted to obtain the fitting relationship between the resistance and rate of the card battery at the target temperature. Based on the fitting relationship between the resistance and the rate of the card battery and the target rate, the target resistance at the target rate is obtained.

6. The method for predicting the resistance of a square battery according to claim 1, characterized in that, The relationship between the diffusion resistance of the card battery and the square battery includes: The product of the ratio of the area of ​​the square battery electrode to the area of ​​the card battery electrode and the diffusion coefficient; wherein the diffusion coefficient includes the ratio of the porosity of the card battery electrode to the porosity of the square battery electrode, and an exponential term with respect to temperature, discharge rate and SOC.

7. The method for predicting the resistance of a square battery according to claim 1, characterized in that, The method further includes: Based on the decomposition test results of the mechanical components of the square battery and the relevant resistance calculation formula, the resistance of the mechanical components of the square battery is obtained; wherein, the mechanical components of the square battery include terminals, adapter plates, and tabs on several electrode plates.

8. A square battery resistance prediction device, characterized in that, It includes a memory, one or more processors, and one or more applications, wherein the one or more applications are stored in the memory and are configured to, when invoked by the one or more processors, cause the one or more processors to perform the method as described in any one of claims 1-7.

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