Battery preparation method

Abstract

The invention relates to a battery preparation method. The battery preparation method comprises the following steps: obtaining a to-be-treated winding battery cell; carrying out hot pressing treatment on the to-be-treated winding battery cell, and detecting whether the surface hardness of the hot-pressed winding battery cell reaches a preset hardness range or not; packaging the wound battery cell with the surface hardness reaching a preset hardness range into a shell as a target battery cell; and removing the wound battery cells with the surface hardness outside the preset hardness range. According to the scheme provided by the invention, whether the surface hardness of the wound battery cell is in the preset hardness range or not can be detected after the wound battery cell is subjected to hot pressing, the wound battery cell with the surface hardness reaching the preset hardness range is sub-packaged into the shell, and the wound battery cell with the surface hardness not reaching the preset hardness range is removed; therefore, the phenomenon that the wound battery cell subjected to excessive hot pressing enters the packaging and shell-entering process is effectively reduced, the production quality of the battery is effectively improved, the yield of packaging and shell-entering of the wound battery cell is effectively improved, and the production efficiency of the battery is improved.

Description

Technical Field

[0001] The present application relates to the technical field of battery manufacturing, and in particular to a method for preparing a battery. Background Art

[0002] Soft-pack lithium-ion batteries are prone to fluffy cells during production, especially wound cells, which can easily lead to a low yield when the cells are packaged into shells. In order to improve the packaging quality of the battery, it is generally adopted to perform high-temperature hot pressing on the cells before packaging to quickly shape the cells, alleviate the fluffy problem of the cells, and thus improve the packaging yield of the cells.

[0003] In the related art, the same hot pressing process is generally used to hot press the same batch of battery cells, that is, the same hot pressing parameters are used to hot press the same batch of battery cells; the above hot pressing method is prone to excessive hot pressing of some battery cells or insufficient hot pressing of some battery cells; when the battery cells are excessively hot pressed, under the same static conditions after liquid filling, the middle part of the battery cells that are excessively hot pressed has insufficient electrolyte infiltration, which leads to the problem of lithium plating ridges in the battery products used in the battery cells after the battery cells are insufficiently infiltrated with electrolyte after capacity division, thus affecting the production quality; when the battery cells are not charged during hot pressing, the problem of bulkiness of the battery cells will still exist, affecting the subsequent packaging and shelling yield of the battery cells and affecting the production efficiency. Summary of the invention

[0004] In order to solve or partially solve the problems existing in the related art, the present application provides a battery preparation method, which can detect whether the surface hardness of the wound battery cell is within a preset hardness range after the wound battery cell is hot-pressed, and the wound battery cells whose surface hardness reaches the preset hardness range are packaged into shells, while the wound battery cells whose surface hardness does not reach the preset hardness range are discarded, thereby effectively reducing the number of wound batteries that are over-hot-pressed and entering the packaging and shelling process, effectively improving the production quality of the battery, and effectively improving the yield of the wound battery cells being packaged into shells, thereby improving the production efficiency of the battery.

[0005] The first aspect of the present application provides a battery preparation method, comprising: Obtaining a wound battery cell to be processed; Performing hot pressing on the wound battery cell to be processed, and detecting whether the surface hardness of the wound battery cell after hot pressing reaches a preset hardness range; The wound battery cell whose surface hardness reaches the preset hardness range is encapsulated into a shell as a target battery cell; The wound battery cells whose surface hardness is outside the preset hardness range are discarded.

[0006] In some embodiments, the preset hardness range is obtained by: Obtaining a plurality of test cells of the same model as the wound cell to be processed, and performing heat pressing treatments to the plurality of test cells to different degrees; Performing a hardness test on each test cell after the hot pressing treatment to obtain the surface hardness of each test cell; Package each test cell into a shell and count the shell yield of all test cells; The fully charged interface of the test cell in the disassembled formed and capacity-divided battery; The surface hardness range of the test cell corresponding to the qualified shelling yield and the fully charged interface is determined as the preset hardness range.

[0007] In some embodiments, the method further comprises: Determine multiple surface hardness boundary values ​​according to pre-division rules; The surface hardnesses of the test cells after the multiple hot pressing treatments respectively correspond to the surface hardness intervals formed between the multiple surface hardness boundary values; The step of determining the surface hardness range of the test cell corresponding to the qualified shelling yield and the fully charged interface as the preset hardness range includes: The surface hardness interval corresponding to the qualified shelling yield and the surface hardness of the test cell corresponding to the fully charged interface is determined as the preset hardness range.

[0008] In some embodiments, the preset hardness range is 50HD-90HD.

[0009] In some embodiments, detecting whether the surface hardness of the wound battery core reaches a preset hardness range includes: Placing the wound battery cell on a preset fixture, wherein the preset fixture is a middle suspended structure, so that the bottom of the battery cell corresponding to the surface of the wound battery cell on which the hardness value is measured is suspended; The hardness value of the surface of the wound battery cell is obtained by a hardness measuring device to determine whether the hardness value reaches a preset hardness range.

[0010] In some embodiments, the step of obtaining the hardness value of the surface of the wound battery cell by a hardness measuring device includes: The hardness value of the middle area of ​​the surface of the wound battery core is obtained by a hardness measuring device.

[0011] In some embodiments, before performing the heat pressing treatment, the method further comprises: Obtain preset heat pressing parameters in advance; The step of hot pressing the wound battery cell to be processed comprises: The wound battery cell to be processed is subjected to hot pressing treatment according to the preset hot pressing parameters.

[0012] In some implementations, the hot pressing parameters of the test cell corresponding to the qualified shelling yield and the fully charged interface are determined as the preset hot pressing parameters.

[0013] In some embodiments, the preset hot pressing parameters include temperature, pressure and time.

[0014] In some embodiments, the temperature is 25° C.-55° C., the pressure is 100 kgf-400 kgf, and the time is 1 second-3 seconds.

[0015] The technical solution provided by this application may have the following beneficial effects: The technical solution of the present application detects the surface hardness of the wound battery cell after hot pressing treatment, uses the surface hardness of the wound battery cell to characterize the degree of completion of the wound battery cell during the hot pressing process, and packs the wound battery cells whose surface hardness reaches a preset hardness range into shells, while discarding the wound battery cells whose surface hardness does not reach the preset hardness range, thereby effectively reducing the number of wound batteries that are over-hot pressed and entering the packaging and shelling process, effectively improving the production quality of the battery, and effectively improving the yield of the wound battery cell packaging and shelling, thereby improving the production efficiency of the battery.

[0016] Furthermore, the technical solution of the present application obtains preset hot pressing parameters in advance, wherein the preset hot pressing parameters correspond to wound cells with qualified shell yield and full-charge interface, and uses the above preset hot pressing parameters to perform hot pressing treatment on the wound cells to be treated, thereby effectively improving the accuracy of hot pressing treatment of the wound cells, and the surface hardness of the wound cells after hot pressing treatment can be more closely aligned with the surface hardness range of qualified shell yield and full-charge interface, thereby effectively preventing overpressure of the wound cells; and by determining the preset hardness range in advance based on the test cells with qualified shell yield and full-charge interface, the accuracy of judging the degree of hot pressing treatment of the wound cells can be further improved, thereby further improving the quality of battery production.

[0017] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The above and other objects, features and advantages of the present application will become more apparent by describing in more detail exemplary embodiments of the present application in conjunction with the accompanying drawings, wherein the same reference numerals generally represent the same components in the exemplary embodiments of the present application.

[0019] Figure 1 is a schematic flow chart of a battery preparation method shown in an embodiment of the present application; Figure 2It is another schematic flow chart of the battery preparation method shown in the embodiment of the present application. DETAILED DESCRIPTION

[0020] The embodiments of the present application will be described in more detail below with reference to the accompanying drawings. Although the embodiments of the present application are shown in the accompanying drawings, it should be understood that the present application can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to make the present application more thorough and complete, and to fully convey the scope of the present application to those skilled in the art.

[0021] The terms used in this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The singular forms of "a", "said" and "the" used in this application and the appended claims are also intended to include plural forms unless the context clearly indicates other meanings. It should also be understood that the term "and / or" used herein refers to and includes any or all possible combinations of one or more associated listed items.

[0022] It should be understood that although the terms "first", "second", "third", etc. may be used in this application to describe various information, this information should not be limited to these terms. These terms are only used to distinguish the same type of information from each other. For example, without departing from the scope of this application, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0023] Soft-pack lithium-ion cells, especially rolled cells, are usually hot-pressed and shaped during the production process to alleviate the fluffy problem of the cells and improve the yield of the cells when they are packaged into shells. In the related art, the same hot-pressing process is generally used to hot-press the cells of the same batch, that is, the same hot-pressing parameters are used to hot-press the cells of the same batch; the above hot-pressing method is prone to excessive hot-pressing of some cells or insufficient hot-pressing of some cells; when the cells are over-hot-pressed, the middle part of the over-hot-pressed cells is insufficiently wetted with electrolyte after being placed under the same static conditions after injection, which leads to the problem of lithium plating convex marks in the battery products used by the cells after the cells are insufficiently wetted with electrolyte after being divided into capacities; when the cells are not charged during hot-pressing, the fluffy problem of the cells will still exist, affecting the subsequent packaging yield of the cells and affecting production efficiency.

[0024] In addition, in the related art, generally after the battery cell is hot pressed, the resting time and resting temperature of the battery cell after liquid injection are increased to promote the full infiltration of the electrolyte into the battery cell. The above method can improve the infiltration effect inside the battery cell to a certain extent, but extending the resting time prolongs the overall production cycle of the product, and increases the energy consumption caused by the resting, which increases the production cost. At the same time, long-term high-temperature resting can easily damage the electrode structure in the battery cell. For example, long-term high-temperature resting affects the chemical properties of the active layer on the electrode, that is, there is a risk of damaging the electrode structure of the battery cell, affecting the subsequent electrical performance of the battery cell in the long cycle process.

[0025] In response to the above problems, an embodiment of the present application provides a battery preparation method, which can detect whether the surface hardness of the wound battery cell is within a preset hardness range after the wound battery cell is hot-pressed, and the wound battery cells whose surface hardness reaches the preset hardness range are packaged into shells, while the wound battery cells whose surface hardness does not reach the preset hardness range are discarded, thereby effectively reducing the number of wound batteries that are over-hot-pressed and entering the packaging and shelling process, effectively improving the production quality of the battery, and effectively improving the yield of the wound battery cells being packaged into shells, thereby improving the production efficiency of the battery.

[0026] The technical solution of the embodiments of the present application is described in detail below with reference to the accompanying drawings.

[0027] Figure 1 The figure is a schematic diagram of the process of the battery preparation method shown in the embodiment of the present application. The battery preparation method of the present application is mainly used for soft-pack lithium-ion batteries prepared by winding battery cells.

[0028] See also Figure 1 , the battery preparation method of the present application comprises: S110, obtaining a wound battery cell to be processed.

[0029] In this step, a wound battery cell that has been wound is obtained.

[0030] It can be understood that the battery preparation method of the present application can be used for laminated wound cells formed by stacking pole pieces. Specifically, the battery preparation method of the present application is used to perform hot pressing before packaging the wound cells. It can be known that packaging the wound cells is to put the wound cells into an aluminum-plastic film, which is also called the wound cell shelling process.

[0031] S120, performing hot pressing on the wound battery cell to be processed, and detecting whether the surface hardness of the hot pressed wound battery cell reaches a preset hardness range.

[0032] In this step, the obtained wound battery cell is hot pressed, and after hot pressing, the surface hardness of the wound battery cell is tested to see if it reaches a preset hardness range. It can be understood that the preset hardness range corresponds to the surface hardness of the wound battery cell. The preset hardness range can be an interval value. In this application, the surface hardness can be measured by the Shore hardness method.

[0033] S130, encapsulating the wound battery cell whose surface hardness reaches a preset hardness range as the target battery cell into a shell.

[0034] In this step, when it is detected that the surface hardness of the wound battery cell reaches the preset hardness range, it means that the completion of the hot pressing treatment of the wound battery cell meets the requirements, and the wound battery cell with a surface hardness reaching the preset hardness range is encapsulated into a shell as the target battery cell to prepare the corresponding battery product. It can be understood that in this application, the surface hardness of the wound battery cell is used to characterize the degree of hot pressing of the wound battery cell. When the surface hardness of the wound battery cell reaches the preset hardness range, it means that the completion of the hot pressing treatment of the wound battery cell meets the requirements.

[0035] S140, removing wound battery cells with a surface hardness outside a preset hardness range.

[0036] In this step, when it is detected that the surface hardness of the wound battery cell is outside the preset hardness range, it means that the completion degree of the hot pressing treatment of the wound battery cell does not meet the requirements, that is, the wound battery cell may be defective, and the wound battery cell with a surface hardness outside the preset hardness range is discarded.

[0037] It should be understood that there is no particular order between step S130 and step S140.

[0038] In this embodiment, the battery preparation method of the present application detects the surface hardness of the wound battery cell after hot pressing treatment, uses the surface hardness of the wound battery cell to characterize the degree of completion of the wound battery cell during the hot pressing process, and packs the wound battery cells whose surface hardness reaches the preset hardness range into shells, while the wound battery cells whose surface hardness does not reach the preset hardness range are removed, thereby effectively reducing the number of wound batteries that are over-hot pressed and entering the packaging and shelling process, effectively improving the production quality of the battery, and effectively improving the yield of the wound battery cells being packaged into shells, thereby improving the production efficiency of the battery.

[0039] Figure 2 It is another schematic flow chart of the battery preparation method shown in the embodiment of the present application.

[0040] See also Figure 2 , the battery preparation method of the present application comprises: S210, obtaining a wound battery cell to be processed.

[0041] In this step, a wound battery cell that has been wound is obtained.

[0042] S220, obtaining preset hot pressing parameters in advance.

[0043] In this step, preset hot pressing parameters for hot pressing the wound battery cell to be processed are obtained in advance. The preset hot pressing parameters may correspond to the wound battery cell to be processed. For example, the preset hot pressing parameters are obtained by hot pressing multiple test batteries of the same model as the wound battery cell to be processed and then performing performance analysis.

[0044] The preset hot pressing parameters may be determined based on the hot pressing parameters of the test battery cell that meets the preset qualified conditions during the hot pressing process.

[0045] In the present application, the wound battery cells to be processed are known, so step S210 and step 220 may be performed in any order. It should be understood that the battery preparation method of the present application can pre-set different preset hot pressing parameters according to different batches of wound cores to be processed. In other words, the battery preparation method of the present application is applicable to the preparation of batteries of different batches and different specifications.

[0046] In some embodiments, the preset hot pressing parameters include temperature, pressure and time. During the hot pressing process, the wound battery cell is heated and pressurized according to the temperature, pressure and time in the preset hot pressing parameters. It can be understood that the hot pressing process can be implemented by the hot pressing equipment in the relevant technology, which will not be repeated here. Furthermore, the temperature can be 25°C-55°C, the pressure can be 100 kgf-400kgf, and the time can be 1-3S. The use of the above-mentioned preset hot pressing parameters to perform hot pressing on the wound battery cell to be treated can effectively improve the accuracy of the hot pressing process.

[0047] S230, performing hot pressing on the wound battery cell to be processed according to preset hot pressing parameters, and detecting whether the surface hardness of the wound battery cell reaches a preset hardness range.

[0048] In this step, the wound battery cell to be processed is subjected to hot pressing treatment according to the obtained preset hot pressing parameters. It can be understood that the hot pressing treatment process can be implemented by hot pressing equipment in the relevant technology, which will not be described here. After the hot pressing treatment, the surface hardness of the wound battery cell is detected to see whether it reaches the preset threshold.

[0049] The hot pressing process may be composed of a single or multiple hot pressing processes. For example, when the wound battery cell is hot pressed, it may be a single hot pressing process with a temperature of 30°C, a pressure of 200 kgf and a duration of 2 s. For another example, when the wound battery cell is hot pressed, it may be two hot pressing processes with a temperature of 30°C, a pressure of 200 kgf and a duration of 1 s.

[0050] In some embodiments, the preset hardness range is obtained by: S231a, obtaining a plurality of test cells of the same type as the wound cells to be processed, and performing heat pressing treatments to different degrees on the plurality of test cells.

[0051] The test cell can be of the same model as the wound cell to be processed, that is, it can be understood that the test cell has the same model, specifications and other parameters as the wound cell to be processed. In other words, the test cell can be a product of the same batch as the wound cell to be processed. The obtained multiple test cells are subjected to different degrees of hot pressing treatment, so that the multiple test cells have different surface hardnesses after the hot pressing treatment. It can be understood that when multiple test cells are subjected to different degrees of hot pressing treatment, the temperature at which the test cells are heated, the pressure of the pressurization, and the length of time of the hot pressing treatment can be adjusted during the hot pressing process, so that the multiple test cells can be subjected to different degrees of hot pressing treatment, and the multiple test cells can have different surface hardnesses.

[0052] S232a, performing a hardness test on each test cell after the hot pressing treatment to obtain the surface hardness of the test cell.

[0053] A surface hardness test is performed on each test cell that has completed the hot pressing treatment to obtain the surface hardness of each test cell.

[0054] S233a, encapsulating each test cell into a shell, and counting the shell yield of all test cells.

[0055] Each test cell is packaged into a shell, and the shell yield of all test cells is counted. It should be understood that the shell yield corresponds to the probability that there are no defects in the packaging process of the wound cell, such as no shell damage, poor sealing, and other defects.

[0056] S234a, fully charged interface of the test cell in the battery after disassembly, formation and capacity separation.

[0057] Each test cell forms a battery after being packaged into a shell. After all the above battery formation and capacity division, the fully charged interface of the test cell is disassembled after being charged to a fully charged state.

[0058] S235a, determining the surface hardness range of the test cell corresponding to the qualified shelling yield and the fully charged interface as a preset hardness range.

[0059] The surface hardness range corresponding to the test cell with qualified shell yield and full-charge interface is determined as the preset hardness range. Among them, the test cell with qualified shell yield and full-charge interface can be a test cell with a package shell yield greater than 99% and no interface lithium deposition phenomenon.

[0060] It can be understood that the two surface hardness values ​​corresponding to the boundary values ​​in the preset hardness range are the two test cells with qualified shell yield and full-charge interface and the smallest surface hardness and the largest surface hardness.

[0061] Through the above method, the preset hardness range determined corresponds to a wound battery cell with a qualified shell yield and a fully charged interface. In this way, the preset hardness range can be used to quickly determine whether the wound battery cell after hot pressing meets the production requirements.

[0062] In some embodiments, the preset hardness range may be 50HD-90HD.

[0063] In some embodiments, multiple surface hardness boundary values ​​can also be determined according to a pre-division rule; the surface hardness of multiple test cells after hot pressing respectively corresponds to each surface hardness interval formed between the multiple surface hardness boundary values; the surface hardness interval corresponding to the surface hardness of the test cell corresponding to the qualified shell yield and the full-charge interface is determined as the preset hardness range. That is, the preset hardness range in this application is also obtained by the following method: S231b, pre-dividing rules to determine multiple surface hardness boundary values.

[0064] It can be understood that the surface hardness of the test cells after different degrees of hot pressing treatment will fall into each surface hardness interval formed by multiple surface hardness boundary values. For example, by dividing the surface hardness boundary values ​​at the same interval, the surface hardness boundary values ​​can be: 10HD, 20HD, 30HD, 40HD...90HD, 100HD, which can form a surface hardness interval of: <10HD, 10 HD -20HD...80HD-90HD, and >90HD. Of course, the surface hardness boundary values ​​can also be customized according to actual application requirements. For example, the surface hardness boundary values ​​can be: 50HD, 60HD, 70HD, 80HD, 90HD, which can form a surface hardness interval of: <50HD, 50HD to 60HD, 60 HD to 70HD, 70 HD to 80HD, 80 HD to 90HD, and >90HD.

[0065] S232b, obtaining multiple test cells of the same model as the wound cells to be processed, and performing different degrees of hot pressing treatment on the multiple test cells, the surface hardness of the multiple test cells after the hot pressing treatment respectively corresponds to each surface hardness interval formed between the multiple surface hardness boundary values.

[0066] After the test cells are subjected to different degrees of hot pressing, the surface hardnesses of the multiple test cells that have undergone the hot pressing process correspond to the surface hardness intervals formed between the multiple surface hardness boundary values. It should be understood that the hot pressing process of different degrees means that the test cells are hot pressed to the extent that their surface hardnesses correspond to the surface hardness intervals.

[0067] For example, the surface hardness intervals are: <50HD, 50HD to 60HD, 60 HD to 70HD, 70 HD to 80HD, 80HD to 90HD, and >90 HD, respectively. By heating a plurality of test cells, each of the above intervals has at least 5 corresponding test cells, that is, each of the above intervals has at least 5 test cells corresponding to the surface hardness.

[0068] S233b, performing a hardness test on each test cell after the hot pressing treatment to obtain the surface hardness of the test cell.

[0069] S234b, encapsulate each test cell into a shell, and count the shell yield of all test cells.

[0070] S235b, the fully charged interface of the test cell in the battery after disassembly, formation and capacity separation.

[0071] S236b, determining the surface hardness interval corresponding to the surface hardness of the test cell corresponding to the qualified shell yield and the fully charged interface as the preset hardness range.

[0072] After determining the surface hardness interval corresponding to each test cell, the surface hardness interval corresponding to the surface hardness of the test cell corresponding to the qualified shell yield and the full-charge interface is determined as the preset hardness range. As mentioned above, the test cell corresponding to the qualified shell yield and the full-charge interface can be a test cell with a package shell yield greater than 99% and no interface lithium deposition phenomenon, and the preset hardness range can be the surface hardness interval range corresponding to the test cell that meets the above conditions.

[0073] In order to further understand the process of determining the preset hardness range in this application, the following uses the four surface hardness intervals of <50HD, 50HD-70HD, 70HD-90HD and >90HD as examples to explain the process of determining the preset hardness range in this application. Each interval corresponds to 100 pcs of test cells, and the surface hardness value of each test cell is the same or different within the corresponding interval. The results are as shown in Table 1:

[0074] Table 1 Through the data results in Table 1 above, it can be known that in the surface hardness zone of <50HD, all the test cells do not have interface lithium deposition, but the packaging into shell excellence rate is 96%, and the packaging into shell excellence rate is low; in the surface hardness zone of 50HD-70HD, all the test cells do not have interface lithium deposition, and the packaging into shell excellence rate is 99%, and the packaging into shell excellence rate is high; in the surface hardness zone of 70HD-90HD, all the test cells do not have interface lithium deposition, and the packaging into shell excellence rate is 99%, and the packaging into shell excellence rate is high; in the surface hardness zone of >90HD, all the test cells have interface lithium deposition, and the packaging into shell excellence rate is 99%, and the packaging into shell excellence rate is high.

[0075] Therefore, according to the data results in Table 1, it can be determined that 50HD-90HD is the surface hardness range that meets the preset yield conditions. Within the surface hardness range of the preset yield conditions, the wound battery cell can ensure a better packaging efficiency and no interface lithium plating occurs.

[0076] In some implementations, the hot pressing parameters of the test cell corresponding to the qualified shell yield and the fully charged interface may also be determined as the preset hot pressing parameters.

[0077] It can be understood that after determining the test cell corresponding to the qualified shell yield and the full-charge interface, the preset hot pressing parameters for hot pressing the wound cell to be processed are determined according to the hot pressing parameters of the test cell that meets the conditions of qualified shell yield and full-charge interface. It can be understood that the hot pressing parameters of the test cell corresponding to the qualified shell yield and full-charge interface when hot pressing are processed are suitable for preparing target cells that meet the preset conditions (i.e., the preset hardness range). By determining the preset hot pressing parameters in the above manner, and then using the determined preset hot pressing parameters to hot press the wound cell to be processed, the accuracy of the hot pressing of the wound cell can be effectively improved, and the surface hardness of the wound cell after hot pressing can be more closely aligned with the surface hardness interval corresponding to the preset hardness range, thereby effectively preventing the wound cell from overvoltage.

[0078] In some embodiments, the process of detecting the surface hardness of the wound battery cell can be performed simultaneously with the hot pressing of the wound battery cell, that is, the wound battery cell is hot pressed and the surface hardness of the wound battery cell is obtained at the same time. In other embodiments, the process of detecting the surface hardness of the wound battery cell can be performed separately from the hot pressing of the wound battery cell. For example, after hot pressing the wound battery cell for a period of time, the hot pressing is stopped, and the surface hardness of the wound battery cell is detected again, and the entire hot pressing process of the wound battery cell is repeated. In other words, the hot pressing treatment of the wound battery cell can be composed of multiple hot pressing processes of the same time. For example, the duration of each hot pressing process of the wound battery cell can be 1 second. After each hot pressing process, the wound battery cell performs a process of detecting whether the surface hardness of the wound battery cell reaches a preset threshold.

[0079] In some embodiments, detecting whether the surface hardness of the wound battery cell reaches a preset threshold may include: S231c, placing the wound battery cell on a preset fixture, which may be a structure with a middle portion suspended, so that the bottom of the battery cell corresponding to the surface of the wound battery cell where the hardness value is measured is suspended.

[0080] The preset fixture is adapted to the wound battery cell, and the wound battery cell that has been subjected to a preset time of hot pressing treatment is placed in the preset fixture. During the process of measuring the hardness value of the wound battery cell surface, there is no support at the bottom of the wound battery cell, thereby reducing the influence of the force generated by the support on the hardness value measurement process, and the middle suspended structure of the preset fixture can achieve a faster cooling effect on the wound battery cell, thereby reducing the influence of the residual high temperature on the hardness value measurement process when the surface of the wound battery cell is subjected to hot pressing treatment.

[0081] S232c, obtaining the hardness value of the surface of the wound battery cell through a hardness measuring device, and determining whether the hardness value reaches a preset hardness range.

[0082] The hardness value of the surface of the wound battery cell is obtained by a hardness measuring device to determine whether the hardness value reaches the preset hardness range obtained in advance. It can be understood that when the hardness value reaches the preset hardness range, it can be considered that the hot pressing treatment of the current wound battery cell meets the requirements. The hardness measuring device can be a Shore hardness tester, which is not limited here.

[0083] In some embodiments, the hardness value of the middle area of ​​the surface of the wound battery cell can be obtained by a hardness measuring device. That is, in the process of measuring the hardness value of the surface of the wound battery cell, by measuring the hardness value of the middle area of ​​the surface of the wound battery cell, the influence of the force of the preset clamp on the support of the wound battery cell on the measurement process can be further reduced, and the accuracy of the measurement of the hardness value of the surface of the wound battery cell can be further improved.

[0084] S240, encapsulating the wound battery cell whose surface hardness reaches a preset hardness range as the target battery cell into a shell.

[0085] In this step, when it is detected that the surface hardness of the wound battery cell reaches the preset hardness range, it means that the completion of the hot pressing treatment of the wound battery cell meets the requirements, and the wound battery cell with a surface hardness reaching the preset hardness range is encapsulated into a shell as the target battery cell to prepare the corresponding battery product. It can be understood that in this application, the surface hardness of the wound battery cell is used to characterize the degree of hot pressing of the wound battery cell. When the surface hardness of the wound battery cell reaches the preset hardness range, it means that the completion of the hot pressing treatment of the wound battery cell meets the requirements.

[0086] S250, removing the wound battery cells whose surface hardness is outside the preset hardness range.

[0087] In this step, when it is detected that the surface hardness of the wound battery cell is outside the preset hardness range, it means that the completion degree of the hot pressing treatment of the wound battery cell does not meet the requirements, that is, the wound battery cell may be defective, and the wound battery cell with a surface hardness outside the preset hardness range is discarded.

[0088] It should be understood that there is no particular order between step S250 and step S260.

[0089] In this embodiment, the battery preparation method of the present application obtains preset hot pressing parameters in advance, wherein the preset hot pressing parameters correspond to wound cells with qualified shell yield and full-charge interface, and uses the above preset hot pressing parameters to perform hot pressing treatment on the wound cells to be treated, thereby effectively improving the accuracy of hot pressing treatment of the wound cells, and the surface hardness of the wound cells after hot pressing treatment can be more closely aligned with the surface hardness range of qualified shell yield and full-charge interface, thereby effectively preventing overpressure of the wound cells; and the preset hardness range is determined in advance based on the test cells with qualified shell yield and full-charge interface, which can further improve the accuracy of judging the degree of hot pressing treatment of the wound cells, thereby further improving the quality of battery production.

[0090] The embodiments of the present application have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The selection of terms used herein is intended to best explain the principles of the embodiments, practical applications, or improvements to the technology in the market, or to enable other persons of ordinary skill in the art to understand the embodiments disclosed herein.

Claims

1. A method for preparing a battery, characterized in that: include: Obtaining a wound battery cell to be processed; Performing hot pressing on the wound battery cell to be processed, and detecting whether the surface hardness of the wound battery cell after hot pressing reaches a preset hardness range; The wound battery cell whose surface hardness reaches the preset hardness range is encapsulated into a shell as a target battery cell; The wound battery cells whose surface hardness is outside the preset hardness range are discarded.

2. The preparation method according to claim 1, characterized in that: The preset hardness range is obtained by: Obtaining a plurality of test cells of the same model as the wound cell to be processed, and performing heat pressing treatments to different degrees on the plurality of test cells; Performing a hardness test on each test cell after the hot pressing treatment to obtain the surface hardness of each test cell; Package each test cell into a shell and count the shell yield of all test cells; The fully charged interface of the test cell in the disassembled formed and capacity-divided battery; The surface hardness range of the test cell corresponding to the qualified shelling yield and the fully charged interface is determined as the preset hardness range.

3. The preparation method according to claim 2, characterized in that: The method further includes: Determine multiple surface hardness boundary values ​​according to pre-division rules; The surface hardnesses of the test cells after the heat pressing treatment respectively correspond to the surface hardness intervals formed between the surface hardness boundary values; The step of determining the surface hardness range of the test cell corresponding to the qualified shelling yield and the fully charged interface as the preset hardness range includes: The surface hardness interval corresponding to the qualified shelling yield and the surface hardness of the test cell corresponding to the fully charged interface is determined as the preset hardness range.

4. The preparation method according to claim 1, characterized in that: The preset hardness range is 50HD-90HD.

5. The preparation method according to claim 1, characterized in that: The detecting whether the surface hardness of the wound battery core reaches a preset hardness range includes: Placing the wound battery cell on a preset fixture, wherein the preset fixture is a middle suspended structure, so that the bottom of the battery cell corresponding to the surface of the wound battery cell on which the hardness value is measured is suspended; The hardness value of the surface of the wound battery cell is obtained by a hardness measuring device to determine whether the hardness value reaches a preset hardness range.

6. The preparation method according to claim 1, characterized in that: The step of obtaining the hardness value of the surface of the wound battery cell by a hardness measuring device comprises: The hardness value of the middle area of ​​the surface of the wound battery core is obtained by a hardness measuring device.

7. The preparation method according to claim 2, characterized in that: Before the hot pressing treatment, the method further comprises: Obtain preset heat pressing parameters in advance; The step of hot pressing the wound battery cell to be processed comprises: The wound battery cell to be processed is subjected to hot pressing treatment according to the preset hot pressing parameters.

8. The preparation method according to claim 7, characterized in that: The hot pressing parameters of the test cell corresponding to the qualified shelling yield and the fully charged interface are determined as the preset hot pressing parameters.

9. The preparation method according to claim 7, characterized in that: The preset hot pressing parameters include temperature, pressure and time.

10. The preparation method according to claim 9, characterized in that: The temperature is 25° C.-55° C., the pressure is 100 kgf-400 kgf, and the time is 1S-3S.

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