A method for predicting the maximum temperature of lithium-ion battery external short circuit

Abstract

The present invention discloses a method for predicting the maximum temperature of an external short circuit of a lithium-ion battery, comprising: Step S1, performing a short-circuit test on the battery at different short-circuit resistances to obtain the short-circuit current i, the short-circuit time t, the short-circuit temperature T, and the maximum short-circuit temperature T max ; Step S2, integrating i with respect to t to obtain the short-circuit discharge capacity Q, and calculating the product i*Q of i and Q; Step S3, plotting a curve graph of the correspondence between the battery T max and i*Q; Step S4, fitting the correspondence curve graph to obtain a mathematical relationship between T max and i*Q; Step S5, for the battery whose maximum short-circuit temperature is to be predicted, obtaining the maximum short-circuit temperature according to the mathematical relationship. The method for predicting the maximum temperature of an external short circuit of a lithium-ion battery disclosed by the present invention can predict the maximum temperature of a short circuit of a lithium-ion battery, has convenience and real-time performance, and improves the obtaining efficiency of the maximum short-circuit temperature.

Description

Technical Field

[0001] The invention relates to the technical field of lithium ion battery safety, and in particular to a method for predicting the maximum temperature of a lithium ion battery external short circuit. Background Art

[0002] In recent years, the application of lithium-ion batteries in electric vehicles has been rapidly developed and promoted. However, the thermal runaway problem caused by the abuse of lithium-ion batteries has become a major problem hindering the development of electric vehicles.

[0003] Short circuit is a kind of electrical abuse. There are two types of short circuits in lithium-ion batteries: internal short circuit and external short circuit. Internal short circuit is the overlap between the positive and negative electrodes inside the battery, and external short circuit is the overlap between the positive and negative output terminals outside the lithium-ion battery. Compared with internal short circuit, external short circuit is more likely to be caused by some incorrect operation or accidental accidents (for example, insulation rupture, vibration causing metal bracket to loosen, or battery wading, etc.). External short circuit will generate a large current and rapid temperature rise in a short period of time. High temperature causes exothermic chain reaction inside the lithium-ion battery (decomposition and regeneration reaction of SEI film). At the same time, the instability of the high-temperature structure of the ternary positive electrode material (such as the generation of oxygen) increases the risk of thermal runaway and the severity of thermal runaway.

[0004] Temperature is a key factor inducing thermal runaway of lithium-ion batteries. However, due to differences in capacity, short-circuit currents and short-circuit durations caused by different short-circuit resistances, and different states of charge (SOC) of the batteries, the maximum temperatures generated by lithium-ion batteries are different. If the maximum temperature under various conditions is obtained only by testing methods, test resources and test time will be consumed. Therefore, it is very necessary to establish a common method to efficiently obtain the maximum temperature of lithium-ion battery short circuits.

[0005] Regarding the calculation method of the short-circuit temperature of lithium-ion batteries, currently, the prediction of the short-circuit temperature of lithium-ion batteries is usually achieved through simulation methods. However, the characteristics of simulation are large amount of calculation, and many data parameters are required for modeling. It is mostly used for battery design and data analysis, and it is difficult to achieve high efficiency and real-time performance. Summary of the invention

[0006] The purpose of the present invention is to provide a method for predicting the maximum temperature of a lithium-ion battery external short circuit in view of the technical defects in the prior art.

[0007] To this end, the present invention provides a method for predicting the maximum temperature of an external short circuit of a lithium ion battery, which comprises the following steps:

[0008] Step S1, respectively performing short-circuit tests on the lithium-ion battery at a plurality of different short-circuit resistances, obtaining the short-circuit current i and short-circuit time t of the lithium-ion battery in real time during the short-circuit test, and collecting the short-circuit temperature T of the lithium-ion battery in real time, and then determining the short-circuit maximum temperature T of the lithium-ion battery when the short-circuit test is performed at different short-circuit resistances. max ;

[0009] Step S2, for the short-circuit current i and the short-circuit time t corresponding to the short-circuit test with different short-circuit resistances, the short-circuit time t is integrated with the short-circuit current i, and the short-circuit discharge capacity Q of the lithium-ion battery when the short-circuit test is performed with different short-circuit resistances is calculated, and the product i*Q of the short-circuit current i and the short-circuit discharge capacity Q is calculated at the same time;

[0010] Step S3, taking the product of short-circuit current and short-circuit discharge capacity i*Q as the horizontal coordinate, and taking the maximum short-circuit temperature T of the lithium-ion battery when short-circuiting at different short-circuit resistances is used as the horizontal coordinate. max As the ordinate, a corresponding relationship curve diagram between the maximum short-circuit temperature of the lithium-ion battery and the product i*Q of the short-circuit current and the discharge capacity is drawn in a figure;

[0011] Step S4, fitting the corresponding relationship curve to obtain the short-circuit maximum temperature T max The mathematical relationship between the product of short-circuit current and short-circuit discharge capacity i*Q;

[0012] Step S5, for any lithium-ion battery whose maximum short-circuit temperature is to be predicted, the maximum short-circuit temperature of the lithium-ion battery is calculated according to the mathematical relationship obtained in step S4, and the short-circuit current and short-circuit time of the lithium-ion battery during an actual short-circuit process;

[0013] Among them, for the lithium-ion battery whose short-circuit maximum temperature is to be predicted, the short-circuit discharge capacity of the lithium-ion battery is obtained by integrating the short-circuit current i acquired during the actual short-circuit process with the short-circuit time t;

[0014] Among them, the short-circuit current i is the current size of the circuit of the lithium-ion battery during the short-circuit test; the short-circuit time t is the duration of the short-circuit process; the short-circuit temperature T is the temperature of the lithium-ion battery surface collected by the thermocouple during the short-circuit test.

[0015] Preferably, in step S1, the charge state of the lithium-ion battery before the short-circuit test is a fully charged state.

[0016] Preferably, in step S1, a short-circuit test is performed on the lithium-ion battery at a plurality of different short-circuit resistances using an existing short-circuit tester.

[0017] Preferably, in step S4, the mathematical relationship is as follows:

[0018] y=a+bx-cx 2 ;

[0019] Where y represents the maximum short-circuit temperature T max ;

[0020] x represents the product of short-circuit current and short-circuit discharge capacity i*Q;

[0021] a, b and c are constants.

[0022] Preferably, the lithium-ion battery whose maximum short-circuit temperature is to be predicted in step S5 is consistent with the specifications and model of the lithium-ion battery in step S1.

[0023] It can be seen from the technical solution provided by the present invention that, compared with the prior art, the method for predicting the maximum temperature of the external short circuit of a lithium-ion battery provided by the present invention is scientifically designed, and the maximum short-circuit temperature of the lithium-ion battery can be predicted by obtaining the current and time during the lithium-ion short-circuit process. It is convenient and real-time, improves the efficiency of obtaining the maximum short-circuit temperature, and has great practical significance.

[0024] The present invention provides a real-time and convenient method for obtaining the maximum temperature of a lithium-ion battery based on the empirical summary of experimental data. Based on the current and short-circuit time parameters of the short-circuit process, by integrating these parameters, the mathematical relationship between the maximum short-circuit temperature of the lithium-ion battery and the product value of the short-circuit current and the short-circuit capacity is finally derived.

[0025] The method of the present invention is not limited to lithium-ion batteries of a specific capacity, but can be extended to predict the maximum short-circuit temperature of lithium-ion batteries under other conditions (different models, different capacities, different short-circuit resistances, and different SOCs), thus providing guidance for the safety management of electric vehicles. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 A flow chart of a method for predicting the maximum temperature of an external short circuit of a lithium-ion battery provided by the present invention;

[0027] Figure 2 In one embodiment of a method for predicting the maximum temperature of an external short circuit of a lithium-ion battery provided by the present invention, a corresponding relationship curve diagram between the maximum short circuit temperature of the lithium-ion battery and the product i*Q of the short circuit current and the discharge capacity is provided, which shows the mathematical relationship between the capacity and the current product (capacity*current) as the independent variable x and the maximum short circuit temperature as the dependent variable y. DETAILED DESCRIPTION

[0028] In order to enable those skilled in the art to better understand the scheme of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and implementation modes.

[0029] See also Figure 1 The present invention provides a method for predicting the maximum temperature of an external short circuit of a lithium-ion battery, comprising the following steps:

[0030] Step S1, respectively performing short-circuit tests on the lithium-ion battery at a plurality of different short-circuit resistances, obtaining the short-circuit current i and short-circuit time t of the lithium-ion battery in real time during the short-circuit test, and collecting the short-circuit temperature T of the lithium-ion battery in real time, and then determining the short-circuit maximum temperature T of the lithium-ion battery when the short-circuit test is performed at different short-circuit resistances. max ;

[0031] In step S1, in specific implementation, the lithium-ion battery is short-circuited under multiple different short-circuit resistances by using an existing short-circuit tester. For example, the short-circuit test equipment (short-circuit tester) can be a BE-1000A short-circuit tester produced by Guangdong Bell Test Equipment Co., Ltd., which can realize the short-circuit test of lithium-ion batteries with adjustable external short-circuit resistance (1-100mΩ).

[0032] It should be noted that due to the different external short-circuit resistances of lithium-ion batteries caused by different scenarios, the resulting short-circuit behaviors will also be different. Therefore, short-circuit tests with different resistances are performed by adjusting the existing short-circuit tester (resistance range: 1-100mΩ).

[0033] It should be noted that there are two types of short circuits in lithium-ion batteries: internal short circuit and external short circuit. Internal short circuit is the overlap between the positive and negative electrodes inside the battery, and external short circuit is the overlap between the positive and negative electrodes outside the lithium-ion battery. Compared with internal short circuit, external short circuit is more likely to be caused by some incorrect operation or accidents (such as insulation rupture, vibration causing the metal bracket to loosen, or the battery wading, etc.).

[0034] Since temperature is an important factor inducing thermal runaway of lithium-ion batteries, understanding the maximum temperature of external short circuit of lithium-ion batteries plays an important role in predicting the risk of lithium-ion short circuit.

[0035] In step S1, in specific implementation, the lithium-ion battery is pre-connected to the test terminal of the short-circuit tester. On the existing short-circuit tester, the short-circuit resistance value in the test loop can be pre-set and adjusted when performing a short-circuit test.

[0036] It should be noted that the short-circuit current i is the current size of the circuit of the lithium-ion battery during the short-circuit test; the short-circuit time t is the duration of the short-circuit process; the short-circuit temperature T is the temperature of the lithium-ion battery surface collected by the thermocouple during the short-circuit test.

[0037] It should be noted that the maximum short-circuit temperature T max , which is the highest value of multiple short-circuit temperatures T obtained by continuous measurement during the short-circuit test of the lithium-ion battery.

[0038] In step S1 , in a specific implementation, the charge state of the lithium-ion battery before the short-circuit test is a fully charged state, that is, 100% SOC.

[0039] In step S1, in specific implementation, an existing temperature measuring instrument can measure the surface temperature of the lithium-ion battery during the short-circuit test, specifically by directly contacting the temperature measuring element (such as a thermocouple) of the temperature measuring instrument with the outer surface of the four side walls of the battery, so as to directly collect the temperature.

[0040] Step S2, for the short-circuit current i and the short-circuit time t corresponding to the short-circuit test with different short-circuit resistances, the short-circuit time t is integrated with the short-circuit current i, and the short-circuit discharge capacity Q (that is, there are multiple Qs) of the lithium-ion battery when the short-circuit test is performed with different short-circuit resistances is calculated, and the product i*Q of the short-circuit current i and the short-circuit discharge capacity Q is calculated at the same time.

[0041] It should be noted that the short-circuit discharge capacity Q is the amount of electricity released by the lithium-ion battery during the short-circuit test.

[0042] In step S2, in specific implementation, the short-circuit discharge capacity of the lithium-ion battery

[0043] In step S2, in specific implementation, the product of the short-circuit current i and the short-circuit discharge capacity Q is

[0044] Step S3, taking the product of short-circuit current and short-circuit discharge capacity i*Q as the horizontal coordinate, and taking the maximum short-circuit temperature T of the lithium-ion battery when short-circuiting at different short-circuit resistances is used as the horizontal coordinate. max As the ordinate, a corresponding relationship curve diagram (a scatter plot) between the maximum short-circuit temperature of the lithium-ion battery and the product i*Q of the short-circuit current and the discharge capacity is drawn in a figure;

[0045] Step S4, fitting the corresponding relationship curve diagram, specifically, using a polynomial fitting, 2order formula in the existing origin fitting to obtain the short-circuit maximum temperature Tmax The mathematical relationship (i.e. mathematical equation) between the short-circuit current and the product of the short-circuit discharge capacity i*Q;

[0046] In step S5, in specific implementation, the mathematical relationship is as follows:

[0047] y=a+bx-cx 2 ;

[0048] Where y represents the maximum short-circuit temperature T max ;

[0049] x represents the product of short-circuit current and short-circuit discharge capacity i*Q;

[0050] a, b and c are constants;

[0051] a is the intersection of the fitting equation connecting multiple scattered points in the scatter plot (the corresponding relationship curve diagram) and the y-axis, that is, the intercept of the y-axis;

[0052] b is the constant factor of the first-order variable in the formula fitted by the origin polynomial quadratic;

[0053] c is the constant factor of the quadratic variable in the formula fitted by the origin polynomial squared;

[0054] It should be noted that in the scatter plot of the corresponding relationship between the maximum short-circuit temperature of the lithium-ion battery and the product of the short-circuit current and the short-circuit discharge capacity (i.e., the corresponding relationship curve), a polynomial fitting square formula is used for fitting in the origin fitting, a is the intercept of the y-axis, b and c are respectively the constant factors of the linear variable and the quadratic variable in the formula fitted by the origin polynomial square;

[0055] It should be noted that in step S3 and step S4, the product of the short-circuit current and the short-circuit discharge capacity i*Q is used as the independent variable (i.e., as the horizontal coordinate), and the short-circuit maximum temperature T under different short-circuit resistances is max As the dependent variable (i.e. as the ordinate), a graph is drawn, and then by using the origin drawing software produced by the existing origin software OriginLab, a polynomial fitting square formula is used for fitting, and a mathematical relationship between the maximum short-circuit temperature and the product of the short-circuit current and the short-circuit discharge capacity (i*Q) is obtained, so that a mathematical equation for establishing the maximum short-circuit temperature, the short-circuit current, and the short-circuit discharge capacity can be formed. In the present invention, since fitting the curve graph by the origin software is a prior art, it is not described in detail here.

[0056] Step S5, for any lithium-ion battery whose maximum short-circuit temperature is to be predicted, the maximum short-circuit temperature of the lithium-ion battery is calculated according to the mathematical relationship obtained in step S4, and the short-circuit current and short-circuit time (i.e., the duration of the short-circuit state) of the lithium-ion battery during an actual short-circuit process;

[0057] For a lithium-ion battery whose maximum short-circuit temperature is to be predicted, the short-circuit current i acquired during the actual short-circuit process is integrated with the short-circuit time t to obtain the short-circuit discharge capacity of the lithium-ion battery.

[0058] It should be noted that the lithium-ion battery whose maximum short-circuit temperature is to be predicted in step S5 is consistent with the specifications and model of the lithium-ion battery in step S1, that is, they are lithium-ion batteries of the same specifications and the same model.

[0059] It should be noted that, for the lithium-ion battery whose maximum short-circuit temperature is to be predicted, the short-circuit current i and short-circuit time t during the short-circuit process can be acquired in real time by an existing battery management system (BMS) or other existing testing equipment.

[0060] In the present invention, it should be noted that the method for predicting the maximum temperature of the external short circuit of a lithium-ion battery provided by the present invention is based on an empirical formula to establish a mathematical relationship between the maximum short circuit temperature and the short circuit current and the short circuit discharge capacity. The operation is convenient and the amount of data calculation is small. For any lithium-ion battery, the maximum short circuit temperature can be obtained (i.e., predicted) based on the known parameter values ​​of the short circuit current and the short circuit time of the battery.

[0061] In order to more clearly understand the technical solution of the present invention, the technical solution of the present invention is described below through specific embodiments.

[0062] Example 1.

[0063] The present invention will be described in detail below by taking a square aluminum shell lithium ion battery as an example in conjunction with the accompanying drawings to further illustrate the essential features and significant progress of the present invention.

[0064] The method for predicting the maximum temperature of a lithium-ion battery external short circuit provided by the present invention comprises the following steps:

[0065] Step S1, using a short-circuit tester of model BE-1000A (resistance adjustable range; 1-100 mΩ) produced by Guangdong Bell Test Equipment Co., Ltd., to perform short-circuit tests on the lithium-ion battery at multiple different short-circuit resistances, and to obtain the short-circuit current i and short-circuit time t of the lithium-ion battery in real time during the short-circuit test, and to collect the short-circuit temperature T of the lithium-ion battery in real time, and then determine the maximum short-circuit temperature T respectively when the short-circuit test is performed with different short-circuit resistances. max ;

[0066] In Example 1, in step S1, the lithium-ion battery is a square aluminum shell lithium-ion battery, and the battery size is 26.5 mm*148 mm*97.5 mm (width*length*height).

[0067] In Example 1, in step S1, the lithium-ion battery is charged to 4.2V at a constant current of 1C rate (51A) before the short-circuit test, and then switched to constant voltage charging to 0.05C (2.55A). The charge state of the lithium-ion power battery is defined as fully charged, i.e., 100% SOC.

[0068] In Example 1, in step S1, a short-circuit test is performed at multiple different short-circuit resistances by connecting a battery at 100% SOC to a short-circuit tester. The multiple different short-circuit resistances include 4.8mΩ, 5.3mΩ, 7.2mΩ, 7.8mΩ and 10.0mΩ. During the test, a splint is used throughout the test for the lithium-ion battery, and a thermocouple on an existing temperature measuring instrument is attached to the side surface of the battery (i.e., the side with a size of 26.5mm*97.5mm) to collect the temperature.

[0069] Step S2, for the short-circuit current i and the short-circuit time t corresponding to the short-circuit test with different short-circuit resistances, the short-circuit time t is integrated with the short-circuit current i, and the short-circuit discharge capacity Q (that is, there are multiple Qs) of the lithium-ion battery when the short-circuit test is performed with different short-circuit resistances is calculated, and the product i*Q of the short-circuit current i and the short-circuit discharge capacity Q is calculated at the same time.

[0070] In Example 1, in step S2, the short-circuit discharge capacity during the short-circuit process is obtained according to the integral of the short-circuit current and the short-circuit time under the short-circuit conditions of different short-circuit resistances. ), further calculate the product of the short-circuit current i and the discharge capacity Q during the short-circuit process

[0071] Step S3, taking the product of short-circuit current and short-circuit discharge capacity i*Q as the horizontal coordinate, and taking the maximum short-circuit temperature T of the lithium-ion battery when short-circuiting at different short-circuit resistances is used as the horizontal coordinate. max As the ordinate, a corresponding relationship curve diagram (a scatter diagram) between the maximum short-circuit temperature of the lithium-ion battery and the product i*Q of the short-circuit current and the discharge capacity is drawn in a figure;

[0072] Step S4, in Example 1, a mathematical relationship for predicting the maximum short-circuit temperature is established, that is, the product of current and short-circuit capacity i*Q is respectively the independent variable x, the short-circuit maximum temperature T max Make a graph for the dependent variable (y), and then obtain the mathematical relationship through fitting using origin software.

[0073] The mathematical relationship obtained in this embodiment 1 is y=19.21+37.33x-3.66x 2 ;

[0074] In the formula, y represents the maximum short-circuit temperature T max , x represents the product of current and short-circuit capacity i*Q, such as Figure 2 shown.

[0075] Step S5, for a lithium-ion battery, the maximum short-circuit temperature of the lithium-ion battery is calculated based on a mathematical relationship, and the short-circuit current and short-circuit time of the lithium-ion battery during an actual short-circuit process.

[0076] Table 1 below shows a comparison between the measured values ​​and the predicted values, with an error within 3°C. The same idea and method for obtaining the maximum short-circuit temperature in other examples (cells with different capacities and different short-circuit resistances) are used, but they must be completely consistent with the mathematical relationship in this embodiment.

[0077] Table 1: Comparison of short-circuit maximum temperature and predicted maximum temperature in short circuit

[0078]

[0079] Compared with the prior art, the present invention has the following beneficial technical effects:

[0080] The present invention establishes a prediction method for the maximum temperature of the external short circuit of a lithium-ion battery based on the experience summarized in the test process, which has the characteristics of convenient operation and real-time performance, that is, the maximum temperature of the short circuit can be predicted by the short circuit current and short circuit time of the lithium-ion battery. At the same time, the method is not limited to a specific model of battery, and can be extended to the prediction of the maximum temperature of the short circuit of lithium-ion batteries under different capacities, different SOC states, and different short circuit resistance conditions.

[0081] In summary, compared with the prior art, the method for predicting the maximum temperature of the external short circuit of a lithium-ion battery provided by the present invention is scientifically designed. By obtaining the current and time during the lithium-ion short circuit process, the maximum short circuit temperature of the lithium-ion battery can be predicted. It is convenient and real-time, improves the efficiency of obtaining the maximum short circuit temperature, and has great practical significance.

[0082] The present invention provides a real-time and convenient method for obtaining the maximum temperature of a lithium-ion battery based on the empirical summary of experimental data. Based on the current and short-circuit time parameters of the short-circuit process, by integrating these parameters, the mathematical relationship between the maximum short-circuit temperature of the lithium-ion battery and the product value of the short-circuit current and the short-circuit capacity is finally derived.

[0083] The method of the present invention is not limited to lithium-ion batteries of a specific capacity, but can be extended to predict the maximum short-circuit temperature of lithium-ion batteries under other conditions (different models, different capacities, different short-circuit resistances, and different SOCs), thus providing guidance for the safety management of electric vehicles.

[0084] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for predicting the maximum temperature of a lithium-ion battery external short circuit, characterized in that: The following steps are involved: Step S1, respectively performing short-circuit tests on the lithium-ion battery at a plurality of different short-circuit resistances, obtaining the short-circuit current i and short-circuit time t of the lithium-ion battery in real time during the short-circuit test, and collecting the short-circuit temperature T of the lithium-ion battery in real time, and then determining the short-circuit maximum temperature T of the lithium-ion battery when the short-circuit test is performed at different short-circuit resistances. max ; Step S2, for the short-circuit current i and the short-circuit time t corresponding to the short-circuit test with different short-circuit resistances, the short-circuit time t is integrated with the short-circuit current i, and the short-circuit discharge capacity Q of the lithium-ion battery when the short-circuit test is performed with different short-circuit resistances is calculated, and the product i*Q of the short-circuit current i and the short-circuit discharge capacity Q is calculated at the same time; Step S3, taking the product of short-circuit current and short-circuit discharge capacity i*Q as the horizontal coordinate, and taking the maximum short-circuit temperature T of the lithium-ion battery when short-circuiting at different short-circuit resistances is used as the horizontal coordinate. max As the ordinate, a corresponding relationship curve diagram between the maximum short-circuit temperature of the lithium-ion battery and the product i*Q of the short-circuit current and the discharge capacity is drawn in a figure; Step S4, fitting the corresponding relationship curve to obtain the short-circuit maximum temperature T max The mathematical relationship between the product of short-circuit current and short-circuit discharge capacity i*Q; Step S5, for any lithium-ion battery whose maximum short-circuit temperature is to be predicted, the maximum short-circuit temperature of the lithium-ion battery is calculated according to the mathematical relationship obtained in step S4, and the short-circuit current and short-circuit time of the lithium-ion battery during an actual short-circuit process; Among them, for the lithium-ion battery whose short-circuit maximum temperature is to be predicted, the short-circuit discharge capacity of the lithium-ion battery is obtained by integrating the short-circuit current i acquired during the actual short-circuit process with the short-circuit time t; Among them, the short-circuit current i is the current size of the circuit of the lithium-ion battery during the short-circuit test; the short-circuit time t is the duration of the short-circuit process; the short-circuit temperature T is the temperature of the lithium-ion battery surface collected by the thermocouple during the short-circuit test.

2. The method for predicting the maximum temperature of the external short circuit of a lithium-ion battery according to claim 1, characterized in that: In step S1 , the charge state of the lithium-ion battery before the short-circuit test is a fully charged state.

3. The method for predicting the maximum temperature of the external short circuit of a lithium-ion battery according to claim 1, characterized in that: In step S1, a short-circuit test is performed on a lithium-ion battery at a plurality of different short-circuit resistances using an existing short-circuit tester.

4. The method for predicting the maximum temperature of the external short circuit of a lithium-ion battery according to claim 1, characterized in that: In step S4, the mathematical relationship is as follows: y=a+bx-cx 2 ; Where y represents the maximum short-circuit temperature T max ; x represents the product of short-circuit current and short-circuit discharge capacity i*Q; a, b and c are constants.

5. The method for predicting the maximum temperature of an external short circuit of a lithium-ion battery according to any one of claims 1 to 4, characterized in that: The lithium-ion battery whose maximum short-circuit temperature is to be predicted in step S5 is consistent with the specifications and model of the lithium-ion battery in step S1.

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