A method for measuring specific heat capacity of a battery

Abstract

The application relates to the field of specific heat capacity measurement, and provides a battery specific heat capacity measurement method, which comprises the following steps: acquiring the mass and temperature time sequence record of a battery, acquiring the temperature time sequence record, specific heat capacity and mass of a cooling liquid and a heater, acquiring the heating power and working time of a lithium battery and calculating the total input heat; inputting the temperature time sequence records of the battery, the cooling liquid and the heater into a temperature drop amplitude calculation model to respectively calculate the temperature drop amplitude caused by heat loss; and inputting the specific heat capacity, mass and input specific heat capacity of the battery, the cooling liquid and the heater into a battery specific heat capacity calculation model to obtain the battery specific heat capacity. When the battery specific heat capacity measurement method is used, the cooling curve is divided into a rapid cooling area and a slow cooling area when the temperature drop amplitude is calculated, and the temperature drop amplitude is calculated in sections, so that the method has the advantages of short test period, low cost, easy operation and the like.

Description

Technical Field

[0001] This invention relates to the field of battery specific heat capacity measurement and identification, and more specifically, to a method for measuring battery specific heat capacity. Background Technology

[0002] With the continuous increase in energy density and fast charging demand of new energy vehicles, large-size, high-capacity lithium-ion batteries have become the mainstream technology. However, as the energy density of lithium-ion batteries continues to rise, the risk of performance degradation and even thermal runaway caused by heat accumulation is becoming increasingly severe.

[0003] In response to the heat generation and heat transfer phenomena that accompany the energy storage and conversion process of power lithium-ion batteries, it is crucial to design appropriate thermal management strategies for battery modules to slow down the rate of battery capacity decay and improve safety. Specific heat capacity parameter is a key parameter in the thermal management design of lithium-ion batteries, and the accuracy of its measurement directly affects the effectiveness of the battery thermal safety model.

[0004] In previous studies, when using conventional methods to test the specific heat capacity of batteries, heat loss factors were often ignored, which increased the error.

[0005] To address this issue, we propose a method for measuring the specific heat capacity of batteries. Summary of the Invention

[0006] Technical problems to be solved

[0007] To address the problems existing in the prior art, the present invention aims to provide a method for measuring the specific heat capacity of a battery. When calculating the specific heat capacity, the concept of heat loss is incorporated and the cooling curve is divided to calculate the total cooling range, making the total cooling range more accurate and the battery specific heat capacity calculation result more accurate, which facilitates the design of subsequent battery thermal management.

[0008] Technical solution

[0009] To solve the above problems, the present invention adopts the following technical solution.

[0010] A method for measuring the specific heat capacity of a battery, the method comprising:

[0011] Acquire battery mass and temperature time-series records; acquire coolant and heater temperature time-series records, specific heat capacity, and mass; acquire lithium battery heating power and operating time; and calculate total input heat. ;

[0012] The temperature time series records corresponding to the battery, the coolant, and the heater are input into the temperature drop calculation model to calculate the temperature drop amplitude respectively. ( (This refers to the total temperature drop caused by heat loss from the battery, coolant, and heater), where the... This is due to the temperature drop caused by heat loss;

[0013] The specific heat capacity and mass of the battery, the coolant, and the heater, and the... and stated Input specific heat capacity calculation model to obtain ( (Specific heat capacity of the battery).

[0014] The heating power and operating time of the lithium battery are obtained and calculated. The steps include:

[0015] Obtain the heating power of the lithium battery, i.e. and working hours ;

[0016] Based on the heat formula

[0017]

[0018] get, .

[0019] The temperature time series records corresponding to the battery, the coolant, and the heater are input into the temperature drop calculation model for calculation. The steps include:

[0020] Based on the temperature time-series records of the battery, a battery temperature change curve is constructed, and the battery temperature change curve is divided into multiple sub-change curves.

[0021] Calculate the slope of the sub-change curve, and divide the battery temperature curve into a heating zone and a cooling zone based on the magnitude of the slope;

[0022] Set a threshold for the absolute value of the slope difference between adjacent sub-curves in the cooling zone, and divide the cooling zone into a rapid cooling zone and a slow cooling zone based on the absolute value of the slope difference.

[0023] Calculated based on the rapid cooling zone and the slow cooling zone respectively ( (rapid cooling rate) and ( (slow cooling rate), the aforementioned and the Adding them together gives ( (Total battery temperature drop)

[0024] The coolant and the heater are subjected to the above steps repeatedly to obtain respectively. ( (total coolant temperature drop) and ( (Total temperature drop of the heater).

[0025] The specific heat capacity, mass, and other parameters of the battery, coolant, and heater are described. and Input specific heat capacity calculation model to obtain ( The steps for determining the specific heat capacity of the battery include:

[0026] The Substitute into the formula to calculate The specific formula is as follows:

[0027]

[0028] Repeat the above steps to calculate respectively. as well as ;

[0029] Based on the above The above and the Adding them together yields the results. The specific formula is as follows:

[0030]

[0031] The calculation based on heat loss The specific formula is as follows:

[0032] .

[0033] The step of setting a threshold for the absolute value of the slope difference between adjacent sub-curves in the cooling zone, and dividing the cooling zone into a rapid cooling zone and a slow cooling zone based on the threshold for the absolute value of the slope difference, includes:

[0034] Confirm the threshold value of the absolute value of the slope difference between adjacent sub-curves in the cooling zone;

[0035] It was confirmed that the two adjacent sets of sub-change curves in the cooling zone were the first sub-change curve and the second sub-change curve, respectively.

[0036] Calculate the slopes of the first sub-curve and the second sub-curve respectively, and subtract the two sets of slopes to obtain the absolute value of the slope difference;

[0037] The absolute value of the slope difference is compared with a threshold value for the absolute value of the slope difference. If the absolute value of the slope difference is less than the threshold value for the absolute value of the slope difference:

[0038] Then, multiple sets of time and corresponding battery temperatures are taken after the first sub-curve of the battery temperature change curve.

[0039] Calculate the Pearson correlation coefficient. If the Pearson correlation coefficient is less than -0.3 or greater than 0.3, then the curve after the first sub-curve of the battery temperature change curve is taken as the slow cooling curve.

[0040] The end point of the heating zone of the battery temperature change curve and the starting point of the slow cooling curve are taken as the rapid cooling curve.

[0041] The calculations based on the rapid cooling zone and the slow cooling zone are respectively... as well as The steps include:

[0042] Based on the characteristic that the rapid cooling zone is a non-linear curve, the maximum temperature drop rate is calculated, and the calculation is based on the maximum temperature drop rate. ;

[0043] Based on the characteristic that the slow temperature drop region is close to a linear curve, the average temperature drop rate is calculated, and the calculation is based on the average temperature drop rate. .

[0044] Based on the characteristic that the rapid cooling zone is a non-linear curve, the maximum temperature drop rate is calculated, and the calculation is based on the maximum temperature drop rate. The steps include:

[0045] Calculate the slope of the sub-variation curve. The value with the largest absolute slope is identified as... Moment ;

[0046] The result of the subsequent integration is:

[0047] .

[0048] Based on the characteristic that the slow temperature drop region is close to a linear curve, the average temperature drop rate is calculated, and the calculation is based on the average temperature drop rate. The steps include:

[0049] Based on the characteristics of the slow temperature drop, calculate ;

[0050] Then, based on the formula, we obtain: .

[0051] The formula for calculating the Pearson correlation coefficient includes:

[0052] ;

[0053] in, , ( Let be the independent variable of the temperature change curve. (The dependent variable in the temperature change curve).

[0054] Multiple sets of data were obtained based on the temperature change curve. and the corresponding Substituting into the above formula yields the Pearson correlation coefficient.

[0055] The specific heat capacity calculation formula includes:

[0056] based on and Adding them together gives The formula for calculating specific heat capacity is transformed into

[0057] .

[0058] Beneficial effects: Compared with the prior art, the advantages of this invention are:

[0059] This invention uses a temperature drop analysis method to calculate the temperature drop caused by heat loss in lithium batteries. This allows for the calibration of the heat dissipated by each component in the lithium battery, leading to a more accurate calculation of the battery's heat dissipation. When calculating the temperature drop, the cooling curve is divided into a rapid cooling zone and a slow cooling zone for segmented calculation, resulting in a more accurate overall temperature drop result. This leads to a more precise specific heat capacity parameter for the battery, providing a foundation for the design of lithium-ion battery thermal management. This allows for more reasonable battery thermal management settings, reducing the probability of battery damage due to slow heat dissipation. It also offers advantages such as short testing cycles, low cost, and ease of operation. Attached Figure Description

[0060] Figure 1 This is a flowchart of the specific heat capacity measurement method of the present invention;

[0061] Figure 2 This is a flowchart of the total input heat calculation for this invention;

[0062] Figure 3 This is a flowchart illustrating the execution of the temperature drop calculation model of the present invention;

[0063] Figure 4 This is a flowchart illustrating the specific heat capacity calculation model of the present invention.

[0064] Figure 5 This is a flowchart of the specific heat capacity calculation for the present invention;

[0065] Figure 6 This is a schematic diagram illustrating the comparison of experimental data for the present invention; Detailed Implementation

[0066] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0067] Please see Figure 1 A flowchart of a method for measuring the specific heat capacity of a battery, comprising:

[0068] S1. Obtain the battery's mass and temperature time-series records. Temperature time-series records refer to the instantaneous temperature slope at a specific moment, recorded in chronological order. Obtain the temperature time-series records, specific heat capacity, and mass of the coolant and heater. The coolant and heater require materials with known specific heat capacities. Obtain the lithium battery's heating power and operating time, and calculate the total input heat. , The voltage can be supplied by connecting an electric heater to a regulated power supply, so a stable power supply must be ensured when conducting this experiment.

[0069] S2. Record the temperature time sequence of the battery, coolant and heater and plot the temperature change curve. When plotting the curve, the combination of matplotlib (plotting) and scipy.curve_fit (curve fitting) can realize the complete process from data fitting to curve visualization.

[0070] Input the temperature change curve into the temperature drop calculation model and calculate accordingly. ,in, This is due to the temperature drop caused by heat loss;

[0071] S3, The specific heat capacity, mass, and other parameters of the battery, coolant, and heater are... The specific heat capacity of the battery is obtained by calculating the specific heat capacity of the total input heat input specific heat capacity model. The specific heat capacity and mass of the coolant and heater are used to calculate the corresponding heat dissipation. Based on the heat dissipation, the heat dissipation of the battery is calculated. Finally, the specific heat capacity of the battery is obtained and used in the battery thermal management design.

[0072] Please see Figure 2 A flowchart of an image processing model for measuring the specific heat capacity of a battery, including:

[0073] S11. Obtain the battery's mass and temperature time-series records, and obtain the coolant and heater's temperature time-series records, specific heat capacity, and mass.

[0074] S12, Obtain the heating power of the lithium battery. and working hours ;

[0075] Based on the heat formula:

[0076]

[0077] get, During the measurement process, a stable power supply needs to be selected to prevent external unstable factors from affecting the accuracy of the overall results.

[0078] Please see Figure 3 A flowchart of the temperature drop calculation model for a battery specific heat capacity measurement method, including:

[0079] S21. Construct a battery temperature change curve based on the battery's temperature time-series records. Divide the battery temperature change curve into multiple sub-change curves. When dividing the sub-change curves, the time units are small, making the sub-change curves tend to be linear. Therefore, the sub-change curves can be expressed by the formula... calculate.

[0080] S22. Calculate the slope of the sub-change curve. Based on the magnitude of the slope, divide the battery temperature curve into a heating zone and a cooling zone. The heating zone is mainly the process of the battery gradually heating up during operation, while the cooling zone is the process of the battery cooling down autonomously after it stops working.

[0081] S23. Set a threshold for the absolute value of the slope difference between adjacent sub-curves. Based on the threshold for the absolute value of the slope difference, the cooling zone is divided into a fast cooling zone and a slow cooling zone. During cooling, the temperature drops faster in the early stage because the temperature difference between the ambient temperature and the lithium battery is large. However, the cooling rate gradually decreases in the later stage. During slow cooling, the temperature drop is lower. However, if the slow cooling zone is also included in the fast cooling zone, the overall temperature drop value will be lower, which will result in a higher battery specific heat capacity result.

[0082] S24. Calculate the rapid temperature drop amplitude and the slow temperature drop amplitude for the rapid cooling zone and the slow temperature drop zone respectively, and add the rapid temperature drop amplitude and the slow temperature drop amplitude together to obtain... ;

[0083] + ;

[0084] Therefore, in calculation The rapid temperature drop amplitude needs to be calculated separately. and the magnitude of slow temperature drop .

[0085] S25. Repeat the above steps with the coolant and the heater to obtain the following results: ;as well as ;

[0086] Because the specific heat capacity, mass, and installation location of the battery, coolant, and heater are different, the temperature drop ranges between them are different. Therefore, when calculating the temperature drop range, it is necessary to calculate them separately multiple times.

[0087] Please see Figure 4 A flowchart of the specific heat capacity calculation model execution for a battery specific heat capacity measurement method, including:

[0088] S31, will Substitute into the formula to calculate The specific formula is as follows:

[0089] ;

[0090] The heat absorbed by the heated object, the coolant, and the heater itself can all be calculated using the energy conservation formula Q = cmΔT, where c and m are the specific heat capacity and mass, respectively.

[0091] Repeat the above steps to calculate respectively. as well as During actual testing, the temperatures of the battery, coolant, and heater all increased, creating a temperature difference with the surrounding environment and resulting in energy loss. However, due to the different characteristics and installation locations of the battery, coolant, and heater, their temperature drop needs to be calculated separately. Here, b represents the battery, f represents the coolant, and h represents the heater. This is the total heat generated by the battery. Total heat of coolant This represents the total heat capacity of the heater.

[0092] S32, based on , as well as Adding them together gives The specific formula is as follows:

[0093] ;

[0094] S33, Calculate the battery specific heat capacity based on heat loss. The specific formula is as follows:

[0095] .

[0096] Please see Figure 5 A flowchart for calculating the specific heat capacity of a battery specific heat capacity measurement method, including:

[0097] S231. Confirm the threshold value of the absolute value of the slope difference between adjacent sub-curves in the cooling zone. Confirm that the two sets of adjacent sub-curves in the cooling zone are the first sub-curve and the second sub-curve, respectively. Calculate the slope of the first sub-curve and the second sub-curve, respectively, and obtain the absolute value of the slope difference based on the two sets of slopes.

[0098] S232. Compare the absolute value of the slope difference between the first sub-curve and the second sub-curve with the absolute value threshold of the slope difference. If the absolute value of the slope difference is less than the absolute value threshold of the slope difference.

[0099] S233: Then, after the first sub-curve of the battery temperature change curve, take multiple sets of time values ​​and corresponding battery temperatures.

[0100] S234. Calculate the Pearson correlation coefficient. If the Pearson correlation coefficient is less than -0.3 or greater than 0.3, the curve after the first sub-curve of the battery temperature change curve is taken as the slow cooling curve. If the Pearson correlation coefficient is greater than -0.3 and less than 0.3, traverse the next set of first and second sub-curves until a set of sub-curves with a Pearson correlation coefficient less than -0.3 or greater than 0.3 and an absolute value of the slope difference less than the absolute value of the slope difference is found.

[0101] The formula for calculating the Pearson correlation coefficient includes:

[0102] ;

[0103] n: Sample size, i.e., the total number of pairs of observations (X,Y);

[0104] X, Y: Two continuous variables to be analyzed;

[0105] The sum of all values ​​that variable X can take;

[0106] The sum of all values ​​that variable Y can take;

[0107] The sum of the products of corresponding values ​​of X and Y (calculate X×Y for each group first, then sum them);

[0108] The sum of the squares of all values ​​of variable X (calculate X² for each group first, then sum them);

[0109] The sum of the squares of all values ​​of variable Y;

[0110] Based on the documentation, when calculating the Pearson correlation coefficient, Y = X=t;

[0111] The closer the absolute value of the Pearson correlation coefficient is to 1, the stronger the linear trend; the closer it is to 0, the weaker the linear trend. The sign indicates the direction of the correlation, i.e., whether it is positive or negative.

[0112] S235. The end point of the heating zone of the battery temperature change curve and the starting point of the slow cooling curve are taken as the rapid cooling curve.

[0113] The temperature change curve is divided into three regions based on the slope and Pearson coefficient: the heating process, the rapid cooling region, and the slow cooling region.

[0114] In the rapid cooling zone, calculation The specific steps are as follows:

[0115] Calculate the slope of the sub-variation curve The value with the largest absolute slope is identified as... Peak instantaneous temperature drop rate at time 1 That is, the maximum temperature drop rate;

[0116] It is the total decrease in temperature over a period of time, while the rate of temperature drop is... It is the rate of change of temperature over time at a certain moment; the two are related as "rate of change" and "total change". Therefore... The temperature drop rate can be integrated over time, as shown below:

[0117] ;

[0118] In the slow temperature drop region, calculation The steps include:

[0119] Based on the characteristic of slow temperature drop, calculation ( (Average temperature drop rate in the slow temperature drop zone);

[0120] During slow cooling, the curve becomes flat, so there is no significant change in slope in this region. Therefore, based on the formula, we can obtain:

[0121] ;

[0122] The total temperature drop was then calculated, as shown below:

[0123] + ;

[0124] Then calculate sequentially. as well as ;

[0125] Will , as well as Substitute them into the following formulas respectively;

[0126]

[0127] The specific heat capacity of the battery is obtained, where, The specific heat capacity of the coolant. Coolant quality Coolant temperature change measurement The specific heat capacity of the heater. Heater quality, The heater measures temperature changes. The specific heat capacity of the heater. Heater quality, The heater measures temperature changes;

[0128] When calculating specific heat capacity, instruments are usually used to measure the temperature changes between various components. However, in actual experiments, there is a temperature difference between the external environment temperature and the temperature of the object being measured. The greater the temperature difference, the more heat flows from the object to the external environment. Therefore, the actual measured temperature is lower than the ideal temperature. That is, the ideal temperature equals the actual measured temperature plus the heat loss temperature. At the same time, there are many factors that cause heat loss during the heating process, and the variables are not singular, which increases the overall measurement difficulty. Therefore, this application uses the temperature drop analysis method to calculate heat loss separately, which greatly reduces the calculation difficulty and makes the heat loss calculation results more accurate.

[0129] Please see Figure 6 The figure shows the battery specific heat capacity test results considering heat loss three times. Based on this, the battery specific heat capacity without considering heat loss is calculated as follows: the first calculation result is 1562.78 J / (kg·℃), the second calculation result is 1759.49 J / (kg·℃), and the third calculation result is 1546.08 J / (kg·℃).

[0130] At the same time, the results considering heat loss and not considering heat loss will be compared. Figure 6 It can be seen that there is a significant difference between the calculation results considering heat loss and those not considering heat loss. If heat loss is ignored, the calculated specific heat capacity is as high as 1622.78 J / (kg·℃), which is 58.57% higher than the measured average value of 1023.41 J / (kg·℃) after considering heat loss.

[0131] The data above shows that heat loss has a significant impact on the calculated specific heat capacity of the battery, and in Figure 6 In this study, the specific heat capacity of batteries without considering heat loss differs significantly from that of batteries with considering heat loss, which has a substantial impact on the overall thermal management design of batteries.

[0132] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for measuring the specific heat capacity of a battery, characterized in that, The method includes: Acquire the battery's mass and temperature time-series records, acquire the coolant and heater's temperature time-series records, specific heat capacity, and mass, acquire the lithium battery's heating power and operating time, and calculate the total input heat Q. total ; The temperature time series records corresponding to the battery, the coolant, and the heater are input into the temperature drop calculation model to calculate ΔT respectively. x-drop , where ΔT x-drop This is due to the temperature drop caused by heat loss; The specific heat capacity, mass, and ΔT of the battery, the coolant, and the heater are used to determine the specific heat capacity, mass, and ΔT of the battery, the coolant, and the heater. x-drop and the Q total The specific heat capacity c of the battery is obtained by inputting the specific heat capacity calculation model. b ; Specifically, the temperature time series records corresponding to the battery, the coolant, and the heater are input into the temperature drop amplitude calculation model to calculate ΔT respectively. x-drop The steps include: Based on the temperature time-series records of the battery, a battery temperature change curve is constructed. The battery temperature change curve is divided into multiple sub-change curves according to smaller time units, so that each sub-change curve tends to be linear. Calculate the slope of the sub-change curve, and divide the battery temperature curve into a heating zone and a cooling zone based on the magnitude of the slope; Set an absolute value threshold for the slope difference between adjacent sub-curves in the cooling zone, and divide the cooling zone into a rapid cooling zone and a slow cooling zone based on the absolute value threshold of the slope difference. ΔT is calculated based on the rapid cooling zone and the slow cooling zone respectively. b-1 and ΔT b-2 , to the ΔT b-1 and the ΔT b-2 Adding them together gives ΔT b-drop ; The coolant and the heater are subjected to the same steps described above to obtain ΔT respectively. f-drop and ΔT h-drop .

2. The battery specific heat capacity measurement method as described in claim 1, characterized in that, The heating power and operating time of the lithium battery are obtained and Q is calculated. total The steps include: Obtain the heating power P of the lithium battery. in And working time, i.e., t; Based on the heat formula Q=Pt, Q is obtained. total =P in t.

3. The battery specific heat capacity measurement method as described in claim 1, characterized in that, The specific heat capacity, mass, and ΔT of the battery, coolant, and heater are described. x-drop and Q total Input specific heat capacity calculation model to obtain c b The steps include: The ΔT b-drop Substitute into the formula to calculate Q b The specific formula is as follows: Q b =c b m b (ΔT b +ΔT b-drop ); Repeat the above steps to calculate Q. f And Q h ; Based on the Q b The Q f and the Q h Adding them together gives Q. total The specific formula is as follows: Q total =Q b +Q f +Q h ; The c is calculated based on the heat loss. b The specific formula is as follows: c b =[P in t-c f m f (ΔT f +ΔT f-drop )-c h m h (ΔT h +ΔT h-drop )] / [m b (ΔT b +ΔT b-drop )]。 4. The battery specific heat capacity measurement method as described in claim 1, characterized in that, The step of setting an absolute value threshold for the slope difference between adjacent sub-curves of the cooling zone, and dividing the cooling zone into a rapid cooling zone and a slow cooling zone based on the absolute value threshold of the slope difference, includes: Confirm the threshold value of the absolute value of the slope difference between adjacent sub-curves in the cooling zone; It was confirmed that the two adjacent sets of sub-change curves in the cooling zone were the first sub-change curve and the second sub-change curve, respectively. Calculate the slopes of the first sub-curve and the second sub-curve respectively, and subtract the two sets of slopes to obtain the absolute value of the slope difference; The absolute value of the slope difference is compared with a threshold value for the absolute value of the slope difference. If the absolute value of the slope difference is less than the threshold value for the absolute value of the slope difference: Then, multiple sets of time and corresponding battery temperatures are taken after the first sub-curve of the battery temperature change curve. Calculate the Pearson correlation coefficient. If the Pearson correlation coefficient is not less than 0.3 and is greater than -0.3, then the curve after the first sub-curve of the battery temperature change curve is taken as the slow cooling curve. The end point of the heating zone of the battery temperature change curve and the starting point of the slow cooling curve are taken as the rapid cooling curve.

5. The battery specific heat capacity measurement method as described in claim 4, characterized in that, The ΔT is calculated based on the rapid cooling zone and the slow cooling zone respectively. b-1 and ΔT b-2 The steps include: Based on the characteristic that the rapid cooling zone is a nonlinear curve, the maximum temperature drop rate is calculated, and ΔT is calculated based on the maximum temperature drop rate. b-1 ; Based on the near-linear curve characteristic of the slow temperature drop region, the average temperature drop rate is calculated, and ΔT is calculated based on the average temperature drop rate. b-2 .

6. The battery specific heat capacity measurement method as described in claim 4, characterized in that, Based on the characteristic that the rapid cooling zone is a nonlinear curve, the maximum temperature drop rate is calculated, and ΔT is calculated based on the maximum temperature drop rate. b-1 The steps include: Calculate the slope k of the sub-variation curve. b-i =(T bi+1 -T bi ) / (t i+1 -t i The value with the largest absolute slope is identified as k at time t1. b-max ; Then, by integration, we obtain: ΔT b-1 =∫|k b-1 |dt=(1 / 2)k b-max t1 2 The lower limit of integration is t1-t0, and the upper limit of integration is t1.

7. The battery specific heat capacity measurement method as described in claim 4, characterized in that, Based on the characteristic that the slow temperature drop region is close to a linear curve, the average temperature drop rate is calculated, and ΔT is calculated based on the average temperature drop rate. b-2 The steps include: Based on the characteristics of the slow temperature drop, calculate k̄ b-slow =ΔT b-slow / Δt slow ; Then, based on the formula, we obtain: ΔT b-2 =k̄ b-slow ×t1.

8. The battery specific heat capacity measurement method as described in claim 4, characterized in that, The formula for calculating the Pearson correlation coefficient includes: r=[nΣXY-ΣXΣY] / √[(nΣX 2 -(SX) 2 )(nΣY 2 -(SY) 2 )]; Where X=t, Y=T b ; Multiple sets of t and their corresponding T are obtained based on the temperature change curve. b Substituting into the above formula yields the Pearson correlation coefficient.

9. The method for measuring the specific heat capacity of a battery as described in claim 3, characterized in that, The specific heat capacity calculation formula includes: Based on ΔT x-1 With ΔT x-2 Adding them together gives ΔT x-drop The formula for calculating specific heat capacity is transformed into .

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