Electrode assembly hot-pressing effect evaluation method

Abstract

The invention relates to an electrode assembly hot-pressing effect evaluation method which comprises the following steps: respectively taking samples with set areas S for positive plates of an electrode assembly before and after hot-pressing, calculating a weight difference value W of the positive plate samples before and after hot-pressing, and calculating the hot-pressing effect of the electrode assembly on the basis of the weight difference value W and the set areas S, and calculating the surface density rho of the glue and ceramic layer of the hot-pressed positive plate sample, and if the surface density rho of the glue and ceramic layer is greater than or equal to a design requirement value, judging that the hot-pressing shaping of the electrode assembly is qualified. The hot-pressing shaping effect of the electrode assembly under the hot-pressing parameters is reflected through visual data, the operation is simple, a test standard operation program can be formed, production line staff can also smoothly operate the test standard operation program, the test standard operation program is added into daily inspection, the reaction to the hot-pressing effect of the electrode assembly is direct, and specific parameters are compared, so that the test accuracy is improved. And the consistency of battery production is better ensured.

Description

Technical Field

[0001] The present application relates to the field of batteries, and in particular to a method for evaluating the hot pressing effect of an electrode assembly. Background Art

[0002] The battery electrode assembly is the core component of the battery. The wound electrode assembly refers to the stacking of positive electrode sheets, separators and negative electrode sheets by winding. During the winding process, it is necessary to ensure that the positive and negative electrode sheets and separators are in uniform and close contact to reduce internal resistance. At the same time, the tension control system maintains constant tension to ensure the stability and consistency of the winding process. The electrode assembly is encapsulated in the battery shell, filled with electrolyte and sealed to form a complete battery unit.

[0003] In the related art, after the wound electrode assembly is wound, it is necessary to perform hot pressing and shaping on the electrode assembly to fix the electrode assembly for normal flow of subsequent processes. However, there is no objective evaluation of the hot pressing effect, and it is usually based on the subjective experience of process engineers. This cannot form a standard operating procedure for testing and is not conducive to daily monitoring of the production line. Summary of the invention

[0004] The present application provides a method for evaluating the hot pressing effect of an electrode assembly, which can solve the technical problem that there is no objective judgment on the evaluation of the hot pressing effect in the prior art, and the judgment is usually made based on the subjective experience of process engineers, which cannot form a standard operating procedure for testing and is not conducive to daily monitoring of the production line.

[0005] The present application provides a method for evaluating the hot pressing effect of an electrode assembly, and the method for evaluating the hot pressing effect of an electrode assembly comprises the following steps:

[0006] Take samples of the positive electrode sheets of the electrode assembly before and after hot pressing with a set area S, calculate the weight difference W of the positive electrode sheet samples before and after hot pressing, and calculate the glue and ceramic layer density ρ of the positive electrode sheet samples after hot pressing based on the weight difference W and the set area S. If the glue and ceramic layer density ρ is greater than or equal to the design requirement, the hot pressing shaping of the electrode assembly is judged to be qualified.

[0007] In one embodiment, if samples with a set area of ​​S and a set number of N are taken from the positive electrode sheets of the electrode assembly before and after hot pressing, then based on the average weight difference W of the plurality of positive electrode sheet samples before and after hot pressing, 平均重量差值 , calculate the average density of the glue and ceramic layers of multiple positive electrode samples after hot pressing ρ 平均值 , if the average density of rubber and ceramic layers ρ 平均值 If it is greater than or equal to the design requirement value, the electrode assembly is judged to be qualified for hot pressing and shaping;

[0008] Among them, W 平均重量差值=W 热压后平均值 -W 热压前平均值 , ρ 平均值 =W 平均重量差值 / S.

[0009] In one embodiment, the positive electrode sheets of the electrode assembly before and after hot pressing are respectively sampled with a set area S, the weight difference W of the positive electrode sheet samples before and after hot pressing is calculated, and based on the weight difference W and the set area S, the glue and ceramic layer density of the positive electrode sheet sample after hot pressing is calculated. ρ , if the density of the rubber and ceramic layers ρ If it is greater than or equal to the design requirement value, the electrode assembly is judged to be qualified for hot pressing and shaping, including:

[0010] Samples with a set area S are taken from the outermost positive electrode sheets of the electrode assembly before and after hot pressing, and the weight difference W of the outermost positive electrode sheet samples before and after hot pressing is calculated. 最外层差值 And set area S, calculate the glue and ceramic layer density of the outermost positive electrode sample after hot pressing ρ1 ;

[0011] Samples with a set area S are taken from the positive electrode sheets of the middle layer of the electrode assembly before and after hot pressing, and the weight difference W of the positive electrode sheet samples of the middle layer before and after hot pressing is calculated. 中间层差值 And set area S, calculate the glue and ceramic layer density of the positive electrode sample in the middle layer after hot pressing ρ2 ;

[0012] Density of the glue and ceramic layers of the outermost positive electrode sample after hot pressing ρ1 Density of the glue and ceramic layers of the positive electrode samples in the middle layer after hot pressing ρ2 , calculate the average surface density of the glue and ceramic layer of the positive electrode sample after hot pressing ρ JR , if the average surface density of the rubber and ceramic layers ρ JR If it is greater than or equal to the design requirement value, the electrode assembly is judged to be qualified by hot pressing.

[0013] In one embodiment, if the positive electrode sheets of the outermost layer and the middle layer of the electrode assembly before and after hot pressing are respectively taken as samples with set areas of S and N numbers, then based on the average weight difference W of the outermost positive electrode sheet samples before and after hot pressing, 最外层平均重量差值 , the average weight difference W of multiple positive electrode samples in the middle layer before and after hot pressing 中间层平均重量差值 , calculate the average density of the glue and ceramic layers of the positive electrode sample after hot pressing ρ 平均值 , if the average density of rubber and ceramic layers ρ 平均值 If it is greater than or equal to the design requirement value, the electrode assembly is judged to be qualified for hot pressing and shaping;

[0014] Among them, W 最外层平均重量差值 =W 热压后最外层平均值 -W 热压前最外层平均值 , W 中间层平均重量差值 =W 热压后中间层平均值 -W 热压前中间层平均值 , ρ 平均值 =( ρ 最外层平均值 + ρ 中间层平均值 ) / 2, ρ 最外层平均值 =W 最外层平均重量差值 / S, ρ 中间层平均值 =W 中间层平均重量差值 / S.

[0015] In one embodiment, the positive electrode sheets of the electrode assembly before and after hot pressing are respectively sampled with a set area S, the weight difference W of the positive electrode sheet samples before and after hot pressing is calculated, and based on the weight difference W and the set area S, the glue and ceramic layer density of the positive electrode sheet sample after hot pressing is calculated. ρ , if the density of the rubber and ceramic layers ρ If it is greater than or equal to the design requirement value, the electrode assembly is judged to be qualified for hot pressing and shaping, including:

[0016] Samples with a set area S are taken from the outermost positive electrode sheets of the electrode assembly before and after hot pressing, and the weight difference W of the outermost positive electrode sheet samples before and after hot pressing is calculated. 最外层差值 And set area S, calculate the glue and ceramic layer density of the outermost positive electrode sample after hot pressing ρ1 ;

[0017] Samples of a set area S are taken from the innermost positive electrode sheet of the electrode assembly before and after hot pressing, and the weight difference W of the innermost positive electrode sheet samples before and after hot pressing is calculated. 最内层差值 And set area S, calculate the glue and ceramic layer density of the innermost positive electrode sample after hot pressing ρ3 ;

[0018] Density of the glue and ceramic layers of the outermost positive electrode sample after hot pressing ρ1 Density of the glue and ceramic layers of the innermost positive electrode sample after hot pressing ρ3 , calculate the average surface density of the glue and ceramic layer of the positive electrode sample after hot pressing ρ JR , if the average surface density of the rubber and ceramic layers ρ JR If it is greater than or equal to the design requirement value, the electrode assembly is judged to be qualified by hot pressing.

[0019] In one embodiment, if the outermost and innermost positive electrode sheets of the electrode assembly before and after hot pressing are respectively sampled with a set area of ​​S and a number of N, then based on the average weight difference W of the outermost positive electrode sheet samples before and after hot pressing, 最外层平均重量差值 , the average weight difference W of the innermost layer of multiple positive electrode samples before and after hot pressing 最内层平均重量差值 , calculate the average density of the glue and ceramic layers of the positive electrode sample after hot pressing ρ 平均值 , if the average density of rubber and ceramic layers ρ 平均值 If it is greater than or equal to the design requirement value, the electrode assembly is judged to be qualified for hot pressing and shaping;

[0020] Among them, W 最外层平均重量差值 =W 热压后最外层平均值 -W 热压前最外层平均值 , W 最内层平均重量差值 =W 热压后最内层平均值 -W 热压前最内层平均值 , ρ 平均值 =( ρ 最外层平均值 + ρ 最内层平均值 ) / 2, ρ 最外层平均值 =W 最外层平均重量差值 / S, ρ 最内层平均值 =W 最内层平均重量差值 / S.

[0021] In one embodiment, the positive electrode sheets of the electrode assembly before and after hot pressing are respectively sampled with a set area S, the weight difference W of the positive electrode sheet samples before and after hot pressing is calculated, and based on the weight difference W and the set area S, the glue and ceramic layer density of the positive electrode sheet sample after hot pressing is calculated. ρ , if the density of the rubber and ceramic layers ρ If it is greater than or equal to the design requirement value, the electrode assembly is judged to be qualified for hot pressing and shaping, including:

[0022] Samples with a set area S are taken from the outermost positive electrode sheets of the electrode assembly before and after hot pressing, and the weight difference W of the outermost positive electrode sheet samples before and after hot pressing is calculated. 最外层差值 And set area S, calculate the glue and ceramic layer density of the outermost positive electrode sample after hot pressing ρ1 ;

[0023] Samples of a set area S are taken from the positive electrode sheets of the middle layer of the electrode assembly before and after hot pressing, and the weight difference W of the positive electrode sheet samples of the middle layer before and after hot pressing is calculated. 中间层差值 And set area S, calculate the glue and ceramic layer density of the positive electrode sample in the middle layer after hot pressing ρ2 ;

[0024] Samples of a set area S are taken from the innermost positive electrode sheet of the electrode assembly before and after hot pressing, and the weight difference W of the innermost positive electrode sheet samples before and after hot pressing is calculated. 最内层差值 And set area S, calculate the glue and ceramic layer density of the innermost positive electrode sample after hot pressing ρ3 ;

[0025] Density of the glue and ceramic layers of the outermost positive electrode sample after hot pressing ρ1 , the density of the glue and ceramic layers of the positive electrode sample in the middle layer after hot pressing ρ2 Density of the glue and ceramic layers of the innermost positive electrode sample after hot pressing ρ 3. Calculate the average surface density of the glue and ceramic layer of the positive electrode sample after hot pressing ρ JR , if the average surface density of the rubber and ceramic layers ρ JR If it is greater than or equal to the design requirement value, the electrode assembly is judged to be qualified by hot pressing.

[0026] In one embodiment, if the outermost, middle and innermost positive electrode sheets of the electrode assembly before and after hot pressing are respectively sampled with a set area of ​​S and a number of N, then based on the average weight difference W of the outermost positive electrode sheet samples before and after hot pressing, 最外层平均重量差值 , the average weight difference W of multiple positive electrode samples in the middle layer before and after hot pressing 中间层平均重量差值 , the average weight difference W of the innermost layer of multiple positive electrode samples before and after hot pressing 最内层平均重量差值 , calculate the average density of the glue and ceramic layers of the positive electrode sample after hot pressing ρ 平均值 , if the average density of rubber and ceramic layers ρ 平均值 If it is greater than or equal to the design requirement value, the electrode assembly is judged to be qualified for hot pressing and shaping;

[0027] Among them, W 最外层平均重量差值 =W 热压后最外层平均值 -W 热压前最外层平均值 , W 中间层平均重量差值 =W 热压后中间层平均值 -W 热压前中间层平均值 , W 最内层平均重量差值 =W 热压后最内层平均值 -W 热压前最内层平均值 , 平均值 =( ρ 最外层平均值 + ρ 中间层平均值 + ρ 最内层平均值 ) / 3, ρ 最外层平均值 =W 最外层平均重量差值 / S, ρ 中间层平均值=W 中间层平均重量差值 / S, ρ 最内层平均值 =W 最内层平均重量差值 / S.

[0028] In one embodiment, the steps of taking samples of the positive electrode sheets of the electrode assembly before and after hot pressing, each with a set area of ​​S, comprises:

[0029] A pole piece sampler is used to take samples of a set area S from the positive pole pieces of the electrode assembly before and after hot pressing.

[0030] In one embodiment, before taking samples of the positive electrode sheets of the electrode assemblies before and after hot pressing, each sample has a set area of ​​S, including:

[0031] A wound but not hot-pressed electrode assembly and a hot-pressed electrode assembly are prepared.

[0032] The beneficial effects brought by the technical solution provided in the embodiments of the present application include:

[0033] Take samples of the positive electrode sheets of the electrode assembly before and after hot pressing with a set area S, calculate the weight difference W of the positive electrode sheet samples before and after hot pressing, and calculate the glue and ceramic layer density of the positive electrode sheet samples after hot pressing based on the weight difference W and the set area S. ρ , if the density of the rubber and ceramic layers ρ If it is greater than or equal to the design requirement value, the hot pressing and shaping of the electrode assembly is judged to be qualified, otherwise the hot pressing and shaping of the electrode assembly is judged to be unqualified. The effect of hot pressing and shaping of the electrode assembly under the hot pressing parameters is reflected through intuitive data. The operation is simple and a standard operating procedure for testing can be formed. The production line employees can also operate it smoothly and add it to daily inspections. The response to the hot pressing effect of the electrode assembly is relatively direct, and there are specific parameters for comparison, which can better ensure the consistency of battery production. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0035] Figure 1 A schematic diagram of a process for evaluating the hot pressing effect of an electrode assembly;

[0036] Figure 2 The weight collection chart is for five samples of the outermost, middle and innermost positive electrode sheets of the electrode assembly before and after hot pressing. DETAILED DESCRIPTION

[0037] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0038] An embodiment of the present application provides a method for evaluating the hot pressing effect of an electrode assembly, which can solve the technical problem that the prior art has no objective judgment on the evaluation of the hot pressing effect, and usually makes judgments based on the subjective experience of process engineers, which cannot form a standard operating procedure for testing and is not conducive to daily monitoring of the production line.

[0039] It is important to understand that since glue and ceramic layers are set on the diaphragm, after hot pressing, the glue and ceramic layers are both adhered to the positive electrode due to the influence of temperature. Therefore, the weight difference of the positive electrode per unit of the electrode assembly before and after hot pressing is taken to calculate the weight of the glue and ceramic layer per unit area and the surface density to characterize the glue and ceramic situation of the positive electrode, and then objectively evaluate the hot pressing effect of the electrode assembly.

[0040] like Figure 1 As shown, an embodiment of the present application provides a method for evaluating the hot pressing effect of an electrode assembly, and the method for evaluating the hot pressing effect of an electrode assembly comprises the following steps:

[0041] S100: Take samples of the positive electrode sheets of the electrode assembly before and after hot pressing with a set area S, calculate the weight difference W of the positive electrode sheet samples before and after hot pressing, and calculate the glue and ceramic layer density of the positive electrode sheet samples after hot pressing based on the weight difference W and the set area S. ρ , if the density of the rubber and ceramic layers ρ If it is greater than or equal to the design requirement value, the electrode assembly is judged to be qualified for hot pressing and shaping; ρ =W / S.

[0042] In this embodiment, samples of the positive electrode sheets of the electrode assembly before and after hot pressing are taken with a set area S, and the weight difference W of the positive electrode sheet samples before and after hot pressing is calculated. Based on the weight difference W and the set area S, the density of the glue and ceramic layers of the positive electrode sheet samples after hot pressing is calculated. ρ , if the density of the rubber and ceramic layers ρ If it is greater than or equal to the design requirement value, the hot pressing and shaping of the electrode assembly is judged to be qualified, otherwise the hot pressing and shaping of the electrode assembly is judged to be unqualified. The effect of hot pressing and shaping of the electrode assembly under the hot pressing parameters is reflected through intuitive data. The operation is simple and a test standard operating procedure can be formed. The production line employees can also operate it smoothly and add it to daily inspections. The response to the hot pressing effect of the electrode assembly is relatively direct, and there are specific parameters for comparison, which can better ensure the consistency of battery cell production.

[0043] Further, in one embodiment, in S100, the following steps are included:

[0044] S100-1: If the positive electrode sheets of the electrode assembly before and after hot pressing are sampled with a set area of ​​S and a set number of N, then the weight average W of the positive electrode sheet samples before hot pressing is calculated. 热压前平均值 , the average weight of multiple positive electrode samples after hot pressing W 热压后平均值 , the average weight difference W of multiple positive electrode samples before and after hot pressing 平均重量差值 , calculate the average density of the glue and ceramic layers of multiple positive electrode samples after hot pressing ρ 平均值 , if the average density of rubber and ceramic layers ρ 平均值 If it is greater than or equal to the design requirement value, the electrode assembly is judged to be qualified for hot pressing and shaping;

[0045] Among them, W 平均重量差值 =W 热压后平均值 -W 热压前平均值 , ρ 平均值 =W 平均重量差值 / S.

[0046] In this embodiment, W 热压前平均值 =(W 热压前样品1 +W 热压前样品2 ……+W 热压前样品n ) / N,W 热压后平均值 =(W 热压后样品1 +W 热压后样品2 ……+W 热压后样品n ) / N, where W 热压前样品1 , W 热压前样品2 ...W 热压前样品n Respectively represent the weight of positive electrode samples 1, 2, ..., n before hot pressing, W 热压后样品1 , W 热压后样品2 ...W 热压后样品n The weights of positive electrode samples 1, 2, ...n after hot pressing are shown respectively. By taking the weight of multiple samples and calculating the average value, the possible error in the measurement of a single sample can be significantly reduced. This error may come from the non-uniformity of the sample, the accuracy limitation of the measuring instrument, or slight changes during the operation. The average value can more accurately reflect the overall situation and reduce the impact of the error on the final result. The weight data of a single sample may be affected by a variety of accidental factors, while the average value can better represent the general situation of the entire batch or production process. Therefore, by calculating the average value, more representative data can be obtained for evaluating the effect and quality of hot pressing. Using the average value can simplify the subsequent calculation and analysis process. For example, when calculating the average density of the glue and ceramic layers ρ 平均值When the weight difference W is used directly 平均重量差值 Divide by the area S, without calculating for each sample separately. This improves work efficiency and reduces the possibility of errors. By calculating the average value, it is easier to compare data from different batches and different process conditions. This helps to quickly find differences, judge whether the hot pressing effect meets the design requirements, and make corresponding decisions. Using the average value as an evaluation indicator can enhance the credibility and persuasiveness of the results. Because the average value is based on the data of multiple samples, it can better reflect the real situation and reduce the impact of accidental factors or individual outliers on the results.

[0047] Further, in one embodiment, in S100, the following steps are included:

[0048] S100-1: Take samples of the outermost positive electrode sheet of the electrode assembly before and after hot pressing with a set area of ​​S, and calculate the weight difference W of the outermost positive electrode sheet samples before and after hot pressing. 最外层差值 , based on the weight difference W 最外层差值 And set area S, calculate the glue and ceramic layer density of the outermost positive electrode sample after hot pressing ρ 1;

[0049] S100-2: Take samples of a set area S from the positive electrode sheets in the middle layer of the electrode assembly before and after hot pressing, and calculate the weight difference W of the positive electrode sheet samples in the middle layer before and after hot pressing. 中间层差值 , based on the weight difference W 中间层差值 And set area S, calculate the glue and ceramic layer density of the positive electrode sample in the middle layer after hot pressing ρ 2;

[0050] S100-3: Based on the glue and ceramic layer density of the outermost positive electrode sample after hot pressing ρ1 Density of the glue and ceramic layers of the positive electrode samples in the middle layer after hot pressing ρ2 , calculate the average surface density of the glue and ceramic layer of the positive electrode sample after hot pressing ρ JR , if the average surface density of the rubber and ceramic layers ρ JR If it is greater than or equal to the design requirement value, the electrode assembly is judged to be qualified by hot pressing.

[0051] In this embodiment, by sampling the positive electrode sheets of the outermost layer and the middle layer of the electrode assembly and calculating the weight difference, the impact of the hot pressing process on the positive electrode sheets at different positions of the electrode assembly can be evaluated in layers. This helps to understand the distribution of the glue and ceramic layers at different positions during the hot pressing process, as well as their changing patterns. Based on the weight difference and the set area, the glue and ceramic layer densities of the positive electrode sheet samples of the outermost layer and the middle layer after hot pressing can be accurately calculated ( ρ1 andρ2 ). These surface density values ​​directly reflect the actual content of glue and ceramic layers in each layer after hot pressing, providing accurate data support for evaluating the effect of hot pressing. By calculating the average surface density of glue and ceramic layers of the positive electrode sample after hot pressing ρ JR , the overall quality of the electrode assembly can be comprehensively evaluated. This average value takes into account the influence of the outermost layer and the middle layer, so it can more comprehensively reflect the effect of hot pressing shaping. ρ JR If it is greater than or equal to the design requirement value, it means that the hot pressing shaping is qualified, otherwise it needs to be adjusted and optimized. The calculation of the average glue and ceramic surface density after hot pressing after layered evaluation helps to improve the stability of product quality. By monitoring the changes in surface density at different levels, potential quality problems can be discovered in a timely manner and corresponding measures can be taken to improve them. This helps to ensure that each batch of products can meet the quality standards required by the design. The hot pressing process can be optimized by analyzing the difference in glue and ceramic surface density of the positive electrode samples in the outermost and middle layers. For example, if it is found that the surface density of a certain layer is low, it may be necessary to increase the coating amount of the layer or adjust the hot pressing parameters to ensure that the surface density of each layer meets the design requirements. In summary, by executing the three steps of S100-1, S100-2 and S100-3, the hot pressing effect can be evaluated in layers, the surface density can be accurately calculated, the quality of the electrode assembly can be comprehensively evaluated, the stability of product quality can be improved, and the hot pressing process can be optimized. These technical effects jointly ensure the qualification of the hot pressing shaping of the electrode assembly and the stability of product quality.

[0052] Furthermore, in one embodiment, after S100-3, the following steps are included:

[0053] S100-4: If the outermost and middle layers of the positive electrode sheets of the electrode assembly before and after hot pressing are respectively sampled with a set area of ​​S and a number of N, then based on the average weight W of the outermost positive electrode sheet samples before hot pressing 热压前最外层平均值 , the average weight of multiple positive electrode samples on the outermost layer after hot pressing W 热压后最外层平均值 , the average weight of multiple positive electrode samples in the middle layer before hot pressing W 热压前中间层平均值 , the average weight of multiple positive electrode samples in the middle layer after hot pressing W 热压后中间层平均值 , the average weight difference W of multiple positive electrode samples on the outermost layer before and after hot pressing 最外层平均重量差值 , the average weight difference W of multiple positive electrode samples in the middle layer before and after hot pressing 中间层平均重量差值 , calculate the average density of the glue and ceramic layers of the positive electrode sample after hot pressing ρ 平均值 , if the average density of rubber and ceramic layers ρ 平均值 If it is greater than or equal to the design requirement value, the electrode assembly is judged to be qualified for hot pressing and shaping;

[0054] Among them, W 最外层平均重量差值 =W 热压后最外层平均值 -W 热压前最外层平均值 , W 中间层平均重量差值 =W 热压后中间层平均值 -W 热压前中间层平均值 , ρ 平均值 =( ρ 最外层平均值 + ρ 中间层平均值 ) / 2, ρ 最外层平均值 =W 最外层平均重量差值 / S, ρ 中间层平均值 =W 中间层平均重量差值 / S.

[0055] In this embodiment, by taking multiple samples and calculating the average weight difference, the error in the measurement of a single sample can be reduced, thereby improving the accuracy of the evaluation. This average value calculation can more truly reflect the change in the mass of the positive electrode sheets in the outermost and middle layers of the electrode assembly before and after hot pressing. This step not only evaluates the positive electrode sheets in the outermost and middle layers separately, but also comprehensively evaluates the overall quality of the electrode assembly by calculating the average surface density of the two. This layered and comprehensive evaluation method can provide a more comprehensive understanding of the impact of the hot pressing process on the positive electrode sheets in different positions of the electrode assembly. By introducing the concepts of average weight difference and average surface density, this step simplifies the calculation process. Only a few key average values ​​need to be calculated to obtain the average density of the glue and ceramic layers of the electrode assembly after hot pressing, which is convenient for quickly judging whether the hot pressing shaping is qualified. The calculated ρ 平均值 It can be directly compared with the design requirement value, so that quality control personnel can quickly judge whether the hot pressing and shaping of the electrode assembly is qualified. This intuitive comparison method helps to find problems in the production process in a timely manner and take corresponding improvement measures. The production process can be optimized by analyzing the difference in the average surface density of the glue and ceramic layers of the outermost and middle layers of the positive electrode sheet. For example, if it is found that the average surface density of a certain layer is low, it may be necessary to adjust the coating amount, hot pressing parameters or improve the production process to ensure that the surface density of each layer meets the design requirements. In summary, step S100-4 uses the average weight difference of multiple samples to calculate the average density of the glue and ceramic layers of the electrode assembly after hot pressing, which improves the accuracy of the evaluation, realizes a layered and comprehensive evaluation, simplifies the calculation process, facilitates quality control, and optimizes the production process. These technical effects jointly ensure the qualification of the hot pressing and shaping of the electrode assembly and the stability of product quality.

[0056] Further, in one embodiment, in S100, the following steps are included:

[0057] S100-1: Take samples of the outermost positive electrode sheet of the electrode assembly before and after hot pressing with a set area of ​​S, and calculate the weight difference W of the outermost positive electrode sheet samples before and after hot pressing. 最外层差值 , based on the weight difference W 最外层差值 And set area S, calculate the glue and ceramic layer density of the outermost positive electrode sample after hot pressing ρ 1;

[0058] S100-2: Take samples of a set area S from the innermost positive electrode sheet of the electrode assembly before and after hot pressing, and calculate the weight difference W of the innermost positive electrode sheet samples before and after hot pressing. 最内层差值 , based on the weight difference W 最内层差值 And set area S, calculate the glue and ceramic layer density of the innermost positive electrode sample after hot pressing ρ 3;

[0059] S100-3: Based on the glue and ceramic layer density of the outermost positive electrode sample after hot pressing ρ1 Density of the glue and ceramic layers of the innermost positive electrode sample after hot pressing ρ3 , calculate the average surface density of the glue and ceramic layer of the positive electrode sample after hot pressing ρ JR , if the average surface density of the rubber and ceramic layers ρ JR If it is greater than or equal to the design requirement value, the electrode assembly is judged to be qualified by hot pressing.

[0060] In this embodiment, the technical effect is the same as the technical effect description regarding the selection of the positive electrode sheet samples for the outermost and middle layers, except that the positive electrode sheet for the middle layer is replaced by the positive electrode sheet for the innermost layer, which will not be described in detail here.

[0061] Furthermore, in one embodiment, after S100-3, the following steps are included:

[0062] S100-4: If the outermost and innermost positive electrode sheets of the electrode assembly before and after hot pressing are respectively taken from samples with set areas of S and N in number, then based on the average weight W of the outermost positive electrode sheet samples before hot pressing, 热压前最外层平均值 , the average weight of multiple positive electrode samples on the outermost layer after hot pressing W 热压后最外层平均值 , the average weight of multiple innermost positive electrode samples before hot pressing W 热压前最内层平均值 , the average weight of multiple positive electrode samples in the innermost layer after hot pressing W 热压后最内层平均值 , the average weight difference W of multiple positive electrode samples on the outermost layer before and after hot pressing 最外层平均重量差值 , the average weight difference W of the innermost layer of multiple positive electrode samples before and after hot pressing 最内层平均重量差值 , calculate the average density of the glue and ceramic layers of the positive electrode sample after hot pressing ρ 平均值, if the average density of rubber and ceramic layers ρ 平均值 If it is greater than or equal to the design requirement value, the electrode assembly is judged to be qualified for hot pressing and shaping;

[0063] Among them, W 最外层平均重量差值 =W 热压后最外层平均值 -W 热压前最外层平均值 , W 最内层平均重量差值 =W 热压后最内层平均值 -W 热压前最内层平均值 , ρ 平均值 =( ρ 最外层平均值 + ρ 最内层平均值 ) / 2, ρ 最外层平均值 =W 最外层平均重量差值 / S, ρ 最内层平均值 =W 最内层平均重量差值 / S.

[0064] In this embodiment, the technical effect is similar to the above-mentioned description of the technical effect of the positive electrode sheet samples in the outermost layer and the middle layer due to the increase in quantity, and will not be described in detail here.

[0065] Further, in one embodiment, in S100, the following steps are included:

[0066] S100-1: Take samples of the outermost positive electrode sheet of the electrode assembly before and after hot pressing with a set area of ​​S, and calculate the weight difference W of the outermost positive electrode sheet samples before and after hot pressing. 最外层差值 , based on the weight difference W 最外层差值 And set area S, calculate the glue and ceramic layer density of the outermost positive electrode sample after hot pressing ρ1 ;

[0067] S100-2: Take samples of a set area S from the positive electrode sheets in the middle layer of the electrode assembly before and after hot pressing, and calculate the weight difference W of the positive electrode sheet samples in the middle layer before and after hot pressing. 中间层差值 , based on the weight difference W 中间层差值 And set area S, calculate the glue and ceramic layer density of the positive electrode sample in the middle layer after hot pressing ρ 2;

[0068] S100-3: Take samples of a set area S from the innermost positive electrode sheet of the electrode assembly before and after hot pressing, and calculate the weight difference W of the innermost positive electrode sheet samples before and after hot pressing. 最内层差值 , based on the weight difference W 最内层差值 And set area S, calculate the glue and ceramic layer density of the innermost positive electrode sample after hot pressing ρ 3;

[0069] S100-4: Based on the glue and ceramic layer density of the outermost positive electrode sample after hot pressing ρ1 , the density of the glue and ceramic layers of the positive electrode sample in the middle layer after hot pressing ρ2 Density of the glue and ceramic layers of the innermost positive electrode sample after hot pressing ρ 3. Calculate the average surface density of the glue and ceramic layer of the positive electrode sample after hot pressing ρ JR , if the average surface density of the rubber and ceramic layers ρ JR If it is greater than or equal to the design requirement value, the electrode assembly is judged to be qualified by hot pressing.

[0070] In this embodiment, by sampling the outermost, middle and innermost positive electrode sheets of the electrode assembly and calculating the weight difference, the impact of the hot pressing process on the positive electrode sheets at different positions of the electrode assembly can be comprehensively evaluated. This helps to understand the distribution of the glue and ceramic layers at different positions during the hot pressing process and their changing patterns, so as to more accurately judge the hot pressing effect. Based on the weight difference and the set area, the glue and ceramic layer density ( ρ1 , ρ2 and ρ3 ). These surface density values ​​directly reflect the actual content of glue and ceramic layers in each layer after hot pressing, providing accurate data support for evaluating the hot pressing effect.

[0071] By calculating the average surface density of the glue and ceramic layer of the positive electrode sample after hot pressing ρ JR , the overall quality of the electrode assembly can be comprehensively evaluated. This average value takes into account the influence of the outermost layer, middle layer and innermost layer of the electrode assembly, so it can more comprehensively reflect the effect of hot pressing shaping. ρ JRIf it is greater than or equal to the design requirement value, it means that the hot pressing shaping is qualified, otherwise it needs to be adjusted and optimized. Layered evaluation and calculation of the average surface density after hot pressing help improve the stability of product quality. By monitoring the changes in surface density at different levels, potential quality problems can be discovered in time and corresponding measures can be taken to improve them. This helps to ensure that each batch of products can meet the quality standards required by the design. The hot pressing process can be optimized by analyzing the density differences of the glue and ceramic layers of the outermost, middle and innermost positive electrode samples. For example, if it is found that the surface density of a layer is low or high, it may be necessary to adjust the coating amount, hot pressing parameters or improve the production process of the layer to ensure that the density of the glue and ceramic layers of each layer can meet the design requirements and improve the qualified rate and product quality of hot pressing shaping. The evaluation method is simple and easy to understand, and is convenient for quality control personnel and production management personnel to operate and monitor. Through regular sampling and testing, problems in the production process can be discovered in time, and corresponding measures can be taken to improve them, thereby ensuring the stability of the production process and the reliability of the product. In summary, by executing the four steps S100-1, S100-2, S100-3 and S100-4, we can comprehensively evaluate the hot pressing effect, accurately calculate the density of the glue and ceramic layers, comprehensively evaluate the quality of the electrode assembly, improve the stability of product quality, optimize the hot pressing process, and facilitate quality control and production management. These technical effects together ensure the qualification of the hot pressing shaping of the electrode assembly and the stability of product quality.

[0072] Furthermore, in one embodiment, after S100-4, the following steps are included:

[0073] S100-5: If the outermost, middle and innermost positive electrode sheets of the electrode assembly before and after hot pressing are respectively taken with a set area of ​​S and a number of N samples, then based on the average weight W of the outermost positive electrode sheet samples before hot pressing 热压前最外层平均值 , the average weight of multiple positive electrode samples on the outermost layer after hot pressing W 热压后最外层平均值 , the average weight of multiple positive electrode samples in the middle layer before hot pressing W 热压前中间层平均值 , the average weight of multiple positive electrode samples in the middle layer after hot pressing W 热压后中间平均值 , the average weight of multiple innermost positive electrode samples before hot pressing W 热压前最内层平均值 , the average weight of multiple positive electrode samples in the innermost layer after hot pressing W 热压后最内层平均值 , the average weight difference W of multiple positive electrode samples on the outermost layer before and after hot pressing 最外层平均重量差值 , the average weight difference W of multiple positive electrode samples in the middle layer before and after hot pressing 中间层平均重量差值 , the average weight difference W of the innermost layer of multiple positive electrode samples before and after hot pressing 最内层平均重量差值 , calculate the average density of the glue and ceramic layers of the positive electrode sample after hot pressing ρ 平均值 , if the average density of rubber and ceramic layersρ 平均值 If it is greater than or equal to the design requirement value, the electrode assembly is judged to be qualified for hot pressing and shaping;

[0074] Among them, W 最外层平均重量差值 =W 热压后最外层平均值 -W 热压前最外层平均值 , W 中间层平均重量差值 =W 热压后中间层平均值 -W 热压前中间层平均值 , W 最内层平均重量差值 =W 热压后最内层平均值 -W 热压前最内层平均值 , 平均值 =( ρ 最外层平均值 + ρ 中间层平均值 + ρ 最内层平均值 ) / 3, ρ 最外层平均值 =W 最外层平均重量差值 / S, ρ 中间层平均值 =W 中间层平均重量差值 / S, ρ 最内层平均值 =W 最内层最内重量差值 / S.

[0075] Exemplarily, the electrode assembly is tested, such as Figure 2 As shown, 1-1 is the weight of the sample of the outermost positive electrode sheet before hot pressing; 1-2 is the weight of the sample of the middle positive electrode sheet before hot pressing; 1-3 is the weight of the sample of the innermost positive electrode sheet before hot pressing; 2-1 is the weight of the sample of the outermost positive electrode sheet after hot pressing; 2-2 is the weight of the sample of the middle positive electrode sheet after hot pressing; 2-3 is the weight of the sample of the innermost positive electrode sheet after hot pressing; before and after hot pressing, the positive electrode sheet per unit area of ​​the electrode assembly appears weight stratification, which is because after hot pressing, the positive electrode sheet is adhered to the glue and ceramic on the diaphragm, and the glue can strengthen the adhesion between the electrode sheet and the diaphragm, and reduce the wrinkles of the electrode sheet, and the thermal stability of the ceramic improves the safety and electrochemical performance of the battery. Therefore, the adhesion between the two needs to reach a certain degree; the difference in weight of the positive electrode sheet before and after hot pressing is used to calculate the surface density of the glue and ceramic layers, which intuitively reflects the degree of adhesion of the electrode sheet and evaluates the effect of hot pressing. Glue and ceramic surface density of positive electrode sheet samples ρ 平均值 Greater than the design requirement of 0.9mg / cm 2 When the hot pressing process parameters meet the process requirements, it is considered that the hot pressing process parameters meet the process requirements. Otherwise, the hot pressing parameters need to be readjusted to meet the process requirements.

[0076] In this embodiment, by taking multiple samples and calculating the average weight difference, the error and contingency in the measurement of a single sample can be significantly reduced, thereby improving the accuracy and reliability of the evaluation. This method can more truly reflect the quality changes of each layer of the positive electrode sheet before and after hot pressing. This method not only evaluates the outermost layer, middle layer and innermost layer of the positive electrode sheet separately, but also comprehensively evaluates the overall quality of the electrode assembly by calculating the average surface density of each layer. This comprehensive and layered evaluation method can provide a deeper understanding of the impact of the hot pressing process on the positive electrode sheets at different positions of the electrode assembly. By introducing the concepts of average weight difference and average surface density, this method simplifies the calculation process. Only a few key average values ​​need to be calculated to obtain the average density of the glue and ceramic layers of the electrode assembly after hot pressing, which is convenient for quickly judging whether the hot pressing shaping is qualified, thereby improving the evaluation efficiency. The calculated ρ 平均值 It can be directly compared with the design requirement value, which is convenient for quality control personnel to quickly determine whether the hot pressing shaping of the electrode assembly is qualified. At the same time, this method also makes it easier for production managers to monitor the production process, discover potential problems in time and take corresponding improvement measures. The hot pressing process can be optimized by analyzing the average surface density difference of the glue and ceramic layers of the outermost, middle and innermost positive electrode sheets of the electrode assembly. For example, adjust the coating amount, hot pressing parameters or improve the production process to ensure that the surface density of each layer meets the design requirements. This helps to improve the stability and consistency of product quality. Due to the use of a unified evaluation method and calculation formula, data from different batches and different time points are comparable and traceable. This helps companies establish a sound quality management system and achieve continuous improvement and optimization of products.

[0077] Further, in one embodiment, in S100, the following steps are included:

[0078] S100-1: Use a pole piece sampler to take samples of a set area S from the positive pole pieces of the electrode assembly before and after hot pressing.

[0079] In this embodiment, the electrode sampler is a device used to accurately sample from the positive electrode. The specific product types are diverse, including but not limited to the MSK-50 electrode sampler, which is designed for continuous coating machine sampling. It has the characteristics of being small and convenient, and having a sheet-type blade rotary cutting. It is suitable for sampling the coating process of positive and negative electrodes of secondary batteries.

[0080] Furthermore, in one embodiment, before S100, the following steps are included:

[0081] S000: preparing a wound but not hot-pressed electrode assembly and a hot-pressed electrode assembly.

[0082] In this embodiment, preparation work is done in advance for the method for evaluating the hot pressing effect of an electrode assembly.

[0083] In the description of the present application, it should be noted that the terms "upper", "lower", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. Unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be a connection between the two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to the specific circumstances.

[0084] It should be noted that, in this application, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0085] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features applied for herein.

Claims

1. A method for evaluating the hot pressing effect of an electrode assembly, characterized in that: The electrode assembly hot pressing effect evaluation method comprises the following steps: Take samples of the positive electrode sheets of the electrode assembly before and after hot pressing with a set area S, calculate the weight difference W of the positive electrode sheet samples before and after hot pressing, and calculate the glue and ceramic layer density of the positive electrode sheet samples after hot pressing based on the weight difference W and the set area S. ρ , if the density of the rubber and ceramic layers ρ If it is greater than or equal to the design requirement value, the electrode assembly is judged to be qualified by hot pressing.

2. The method for evaluating the hot pressing effect of an electrode assembly according to claim 1, wherein: If the positive electrode sheets of the electrode assembly before and after hot pressing are respectively sampled with a set area of ​​S and a number of N, then based on the average weight difference W of the positive electrode sheet samples before and after hot pressing, 平均重量差值 , calculate the average density of the glue and ceramic layers of multiple positive electrode samples after hot pressing ρ 平均值 , if the average density of rubber and ceramic layers ρ 平均值 If it is greater than or equal to the design requirement value, the electrode assembly is judged to be qualified for hot pressing and shaping; where, W 平均重量差值 = W 热压后平均值 - W 热压前平均值 , ρ 平均值 = W 平均重量差值 / S.

3. The method for evaluating the hot pressing effect of an electrode assembly according to claim 1, wherein: The positive electrode sheets of the electrode assembly before and after hot pressing are respectively sampled with a set area S, and the weight difference W of the positive electrode sheet samples before and after hot pressing is calculated, and based on the weight difference W and the set area S, the density of the glue and ceramic layers of the positive electrode sheet samples after hot pressing is calculated. ρ , if the density of the rubber and ceramic layers ρ If it is greater than or equal to the design requirement value, the electrode assembly is judged to be qualified for hot pressing and shaping, including: Samples with a set area S are taken from the outermost positive electrode sheets of the electrode assembly before and after hot pressing, and the weight difference W of the outermost positive electrode sheet samples before and after hot pressing is calculated. 最外层差值 And set area S, calculate the glue and ceramic layer density of the outermost positive electrode sample after hot pressing ρ1 ; Samples with a set area S are taken from the positive electrode sheets of the middle layer of the electrode assembly before and after hot pressing, and the weight difference W of the positive electrode sheet samples of the middle layer before and after hot pressing is calculated. 中间层差值 And set area S, calculate the glue and ceramic layer density of the positive electrode sample in the middle layer after hot pressing ρ2 ; Density of the glue and ceramic layers of the outermost positive electrode sample after hot pressing ρ1 Density of the glue and ceramic layers of the positive electrode samples in the middle layer after hot pressing ρ2 , calculate the average surface density of the glue and ceramic layer of the positive electrode sample after hot pressing ρ JR , if the average surface density of the rubber and ceramic layers ρ JR If it is greater than or equal to the design requirement value, the electrode assembly is judged to be qualified by hot pressing.

4. The method for evaluating the hot pressing effect of an electrode assembly according to claim 3, wherein: If the outermost and middle layers of the positive electrode sheets of the electrode assembly before and after hot pressing are respectively sampled with a set area of ​​S and a number of N, then based on the average weight difference W of the outermost positive electrode sheet samples before and after hot pressing, 最外层平均重量差值 , the average weight difference W of multiple positive electrode samples in the middle layer before and after hot pressing 中间层平均重量差值 , calculate the average density of the glue and ceramic layers of the positive electrode sample after hot pressing ρ 平均值 , if the average density of rubber and ceramic layers ρ 平均值 If it is greater than or equal to the design requirement value, the electrode assembly is judged to be qualified for hot pressing and shaping; Among them, W 最外层平均重量差值 = W 热压后最外层平均值 - W 热压前最外层平均值 , W 中间层平均重量差值 = W 热压后中间层平均值 - W 热压前中间层平均值 , ρ 平均值 = ( ρ 最外层平均值 + ρ 中间层平均值 ) / 2, ρ 最外层平均值 = W 最外层平均重量差值 / S, ρ 中间层平均值 = W 中间层平均重量差值 / S.

5. The method for evaluating the hot pressing effect of an electrode assembly according to claim 1, wherein: The positive electrode sheets of the electrode assembly before and after hot pressing are respectively sampled with a set area S, and the weight difference W of the positive electrode sheet samples before and after hot pressing is calculated, and based on the weight difference W and the set area S, the density of the glue and ceramic layers of the positive electrode sheet samples after hot pressing is calculated. ρ , if the density of the rubber and ceramic layers ρ If it is greater than or equal to the design requirement value, the electrode assembly is judged to be qualified for hot pressing and shaping, including: Samples with a set area S are taken from the outermost positive electrode sheets of the electrode assembly before and after hot pressing, and the weight difference W of the outermost positive electrode sheet samples before and after hot pressing is calculated. 最外层差值 And set area S, calculate the glue and ceramic layer density of the outermost positive electrode sample after hot pressing ρ1 ; Samples of a set area S are taken from the innermost positive electrode sheet of the electrode assembly before and after hot pressing, and the weight difference W of the innermost positive electrode sheet samples before and after hot pressing is calculated. 最内层差值 And set area S, calculate the glue and ceramic layer density of the innermost positive electrode sample after hot pressing ρ3 ; Density of the glue and ceramic layers of the outermost positive electrode sample after hot pressing ρ1 Density of the glue and ceramic layers of the innermost positive electrode sample after hot pressing ρ3 , calculate the average surface density of the glue and ceramic layer of the positive electrode sample after hot pressing ρ JR , if the average surface density of the rubber and ceramic layers ρ JR If it is greater than or equal to the design requirement value, the electrode assembly is judged to be qualified by hot pressing.

6. The method for evaluating the hot pressing effect of an electrode assembly according to claim 5, wherein: If the outermost and innermost positive electrode sheets of the electrode assembly before and after hot pressing are respectively taken as samples with set areas of S and N numbers, then based on the average weight difference W of the outermost positive electrode sheet samples before and after hot pressing, 最外层平均重量差值 , the average weight difference W of the innermost layer of multiple positive electrode samples before and after hot pressing 最内层平均重量差值 , calculate the average density of the glue and ceramic layers of the positive electrode sample after hot pressing ρ 平均值 , if the average density of rubber and ceramic layers ρ 平均值 If it is greater than or equal to the design requirement value, the electrode assembly is judged to be qualified for hot pressing and shaping; Among them, W 最外层平均重量差值 = W 热压后最外层平均值 - W 热压前最外层平均值 、W 最内层平均重量差值 = W 热压后最内层平均值 - W 热压前最内层平均值 、 ρ 平均值 = ( ρ 最外层平均值 + ρ 最内层平均值 ) / 2, ρ 最外层平均值 = W 最外层平均重量差值 / S, ρ 最内层平均值 = W 最内层平均重量差值 / S。 7. The method for evaluating the hot pressing effect of an electrode assembly according to claim 1, wherein: The positive electrode sheets of the electrode assembly before and after hot pressing are respectively sampled with a set area S, and the weight difference W of the positive electrode sheet samples before and after hot pressing is calculated, and based on the weight difference W and the set area S, the density of the glue and ceramic layers of the positive electrode sheet samples after hot pressing is calculated. ρ , if the density of the rubber and ceramic layers ρ If it is greater than or equal to the design requirement value, the electrode assembly is judged to be qualified for hot pressing and shaping, including: Samples with a set area S are taken from the outermost positive electrode sheets of the electrode assembly before and after hot pressing, and the weight difference W of the outermost positive electrode sheet samples before and after hot pressing is calculated. 最外层差值 And set area S, calculate the glue and ceramic layer density of the outermost positive electrode sample after hot pressing ρ1 ; Samples of a set area S are taken from the positive electrode sheets of the middle layer of the electrode assembly before and after hot pressing, and the weight difference W of the positive electrode sheet samples of the middle layer before and after hot pressing is calculated. 中间层差值 And set area S, calculate the glue and ceramic layer density of the positive electrode sample in the middle layer after hot pressing ρ2 ; Samples of a set area S are taken from the innermost positive electrode sheet of the electrode assembly before and after hot pressing, and the weight difference W of the innermost positive electrode sheet samples before and after hot pressing is calculated. 最内层差值 And set area S, calculate the glue and ceramic layer density of the innermost positive electrode sample after hot pressing ρ3 ; Density of the glue and ceramic layers of the outermost positive electrode sample after hot pressing ρ1 , the density of the glue and ceramic layers of the positive electrode sample in the middle layer after hot pressing ρ2 Density of the glue and ceramic layers of the innermost positive electrode sample after hot pressing ρ 3. Calculate the average surface density of the glue and ceramic layer of the positive electrode sample after hot pressing ρ JR , if the average surface density of the rubber and ceramic layers ρ JR If it is greater than or equal to the design requirement value, the electrode assembly is judged to be qualified by hot pressing and shaping.

8. The method for evaluating the hot pressing effect of an electrode assembly according to claim 7, wherein: If the outermost, middle and innermost positive electrode sheets of the electrode assembly before and after hot pressing are respectively taken with a set area of ​​S and a number of N samples, then based on the average weight difference W of the outermost positive electrode sheet samples before and after hot pressing, 最外层平均重量差值 , the average weight difference W of multiple positive electrode samples in the middle layer before and after hot pressing 中间层平均重量差值 , the average weight difference W of the innermost layer of multiple positive electrode samples before and after hot pressing 最内层平均重量差值 , calculate the average density of the glue and ceramic layers of the positive electrode sample after hot pressing ρ 平均值 , if the average density of rubber and ceramic layers ρ 平均值 If it is greater than or equal to the design requirement value, the electrode assembly is judged to be qualified for hot pressing and shaping; Among them, W 最外层平均重量差值 = W 热压后最外层平均值 - W 热压前最外层平均值 、W 中间层平均重量差值 = W 热压后中间层平均值 - W 热压前中间层平均值 、W 最内层平均重量差值 = W 热压后最内层平均值 - W 热压前最内层平均值 、ρ 平均值 = ( ρ 最外层平均值 + ρ 中间层平均值 + ρ 最内层平均值 ) / 3, ρ 最外层平均值 = W 最外层平均重量差值 / S, ρ 中间层平均值 = W 中间层平均重量差值 / S, ρ 最内层平均值 = W 最内层平均重量差值 / S。 9. The method for evaluating the hot pressing effect of an electrode assembly according to claim 1, wherein: The method of taking samples of the positive electrode sheets of the electrode assembly before and after hot pressing, each with a set area of ​​S, comprises: A pole piece sampler is used to take samples of a set area S from the positive pole pieces of the electrode assembly before and after hot pressing.

10. The method for evaluating the hot pressing effect of an electrode assembly according to claim 1, wherein: Before taking samples of the positive electrode sheets of the electrode assemblies before and after hot pressing, each sample has a set area of ​​S, including: A wound but not hot-pressed electrode assembly and a hot-pressed electrode assembly are prepared.

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