Method for optimizing terminal voltage difference of battery

Abstract

The invention relates to the technical field of battery manufacturing, in particular to an optimization method for the terminal voltage difference of a battery, and provides an optimization method for the terminal voltage difference of the battery, and the optimization method comprises the step of carrying out silicon-containing treatment on a negative electrode material to obtain optimization of a silicon-containing negative electrode material or optimization of carrying out diversified mixing treatment on a positive electrode material, by adopting any one of the optimization modes, the end voltage difference curve slope of the battery can be effectively reduced, the voltage difference between the battery cells at the discharge end is reduced, the overall performance of the battery is improved, and the service life of the battery is prolonged; and by adopting an optimization treatment method based on the original positive electrode material or negative electrode material, the matching success rate and matching inclusiveness can be increased, so that the overall performance and the service life of the battery are improved, the operation process is simple, the implementation is easy, complicated equipment and technical support are not needed, the production cost is reduced, and the production efficiency is improved. The production efficiency is improved.

Description

Technical Field

[0001] The present application belongs to the field of battery manufacturing technology, and in particular relates to a method for optimizing the terminal pressure difference of a battery. Background Art

[0002] The terminal voltage difference of a battery during charge and discharge refers to the voltage difference between the two ends of the battery (i.e., the positive electrode and the negative electrode) during the process of charging and discharging the battery. During the charging process, the positive electrode voltage of the battery will gradually increase, while the negative electrode voltage will be relatively stable or slightly decreased, which will lead to an increase in the terminal voltage difference of charge and discharge, that is, the difference between the positive electrode voltage and the negative electrode voltage of the battery will become larger. During the discharge process, the positive electrode voltage of the electrode will gradually decrease, while the negative electrode voltage will be relatively stable or slightly increased. This will lead to a decrease in the terminal voltage difference of charge and discharge, that is, the difference between the positive electrode voltage and the negative electrode voltage of the battery will become smaller. This change in the terminal voltage difference of charge and discharge is caused by the chemical reaction and current flow inside the battery. The voltage difference between the positive and negative electrodes reflects the potential difference of the battery, that is, the battery's electrical energy conversion and storage.

[0003] Since the terminal voltage difference of battery charge and discharge is very important for judging and monitoring battery performance and working status, by monitoring the terminal voltage difference of battery charge and discharge, we can understand the health status of the battery, capacity growth, battery charge and discharge efficiency and other related information, and provide guidance for battery use and management. Therefore, in the field of battery manufacturing technology, the terminal voltage difference curve of the battery is generally used as an important performance indicator to evaluate the performance of the battery.

[0004] In the graphite system, due to its large terminal slope, when the battery is packed into a module, the voltage difference between the cells at the end of discharge will increase significantly. This phenomenon will have an adverse effect on the overall performance and life of the battery. At present, in order to optimize the terminal pressure difference curve of the graphite battery system, a precise matching method is usually adopted to improve the consistency of the matching, and the consistency between modules is improved by screening the capacity, voltage, internal resistance, K value, etc.; however, due to the material system, the slope of the curve at the end SOC of the graphite system itself is large. The consistency can be optimized by matching at the front end SOC, but the slope of the curve increases at the end SOC, and the consistency difference between the cells is amplified. Therefore, it is urgent to provide a new method for optimizing the terminal pressure difference of the battery. Summary of the invention

[0005] The purpose of the present application is to provide a method for optimizing the terminal pressure difference of a battery, aiming to solve the problem in the prior art that the slope of the terminal pressure difference curve of the battery cannot be completely reduced.

[0006] In order to achieve the above application purpose, the technical solution adopted in this application is as follows:

[0007] In a first aspect, the present application provides a method for optimizing the terminal pressure difference of a battery, comprising the following steps:

[0008] Performing siliconization treatment on the negative electrode material of the battery to obtain a silicon-containing negative electrode material, preparing a plurality of first cells to be tested with the silicon-containing negative electrode material, testing the voltage change of each first cell to be tested under different discharge rate conditions and calculating the maximum voltage difference between each first cell to be tested at the end of discharge, and determining the optimized content of the silicon-containing negative electrode material according to the maximum voltage difference;

[0009] or,

[0010] The positive electrode materials of the battery are subjected to diversified mixing treatment to obtain a multi-component mixed positive electrode material, and a number of second test cells are prepared with the multi-component mixed positive electrode material. The voltage change of each second test cell under different discharge rate conditions is tested and the maximum voltage difference between each second test cell at the end of discharge is calculated, and the optimized content of the multi-component mixed positive electrode material is determined according to the maximum pressure difference.

[0011] In some embodiments, in the silicon-containing negative electrode material, the silicon material includes any one of a silicon-oxygen material, a silicon-carbon deposition material, and a metal silicon material.

[0012] In some embodiments, the step of subjecting the negative electrode material of the battery to siliconization to obtain the silicon-containing negative electrode material includes:

[0013] The silicon-containing negative electrode material is obtained by combining the silicon-containing material with the negative electrode material of the original battery by a layered addition method, or the silicon-containing material is obtained by combining the silicon-containing material with the negative electrode material of the original battery by a mixed addition method.

[0014] In some embodiments, the step of combining the silicon-containing material with the primary battery negative electrode material by a layered addition method to obtain the silicon-containing negative electrode material includes:

[0015] The silicon-containing material is 50 The particle size is divided into the first silicon-containing material and the second silicon-containing material, and the D of the first silicon-containing material 50 The particle size is larger than that of the second silicon-containing material D 50 Small particle size;

[0016] Performing a first mixing process on the first silicon-containing material and the auxiliary material in the negative electrode material to obtain a first mixture, and performing a second mixing process on the second silicon-containing material and the main material in the negative electrode material to obtain a second mixture;

[0017] The first mixture and the second mixture are blended to prepare a silicon-containing negative electrode material.

[0018] In some embodiments, the auxiliary material includes at least one of a conductive agent and a binder.

[0019] In some embodiments, the host material includes graphite.

[0020] In some embodiments, D of the first silicon-containing material 50 The particle size is larger than that of the second silicon-containing material D 50 The particle size is as small as 5 to 10 μm.

[0021] In some embodiments, in the step of combining the silicon-containing material with the original battery negative electrode material by a mixed addition method to obtain the silicon-containing negative electrode material, a physical mixing method or a chemical deposition method is used to deposit silicon on the surface and inside of the original battery negative electrode material in a desired proportion to obtain a mixed material.

[0022] In some embodiments, the optimized content of the silicon-containing negative electrode material is 2 wt % to 15 wt %.

[0023] In some embodiments, the step of performing diversified mixing treatment on the positive electrode material of the battery to obtain a multi-component mixed positive electrode material includes: providing multiple lithium-containing positive electrode materials, mixing the lithium-containing positive electrode materials with different platform curve voltage values ​​to obtain a multi-component mixed positive electrode material; wherein the voltage values ​​of the platform curves of different lithium-containing positive electrode materials subjected to the mixing treatment differ by ≥0.4V.

[0024] In some embodiments, the multi-component mixed positive electrode material is a mixture of at least one of lithium cobalt oxide, lithium manganese oxide, lithium nickel cobalt manganese oxide, and lithium nickel cobalt aluminum oxide and lithium iron phosphate.

[0025] The first aspect of the present application provides a method for optimizing the terminal pressure difference of a battery, which includes optimizing the negative electrode material by silicon-containing treatment to obtain a silicon-containing negative electrode material or optimizing the positive electrode material by diversified mixed treatment. Any of the above optimization methods can be used to more effectively reduce the slope of the terminal pressure difference curve of the battery, reduce the pressure difference between the cells at the end of discharge, and improve the overall performance and life of the battery; and the optimization method based on the original positive electrode material or negative electrode material can increase the combination success rate and combination inclusiveness, thereby improving the overall performance and life of the battery, and the operation process is simple and easy to implement, without the need for complex equipment and technical support, which is conducive to reducing production costs and improving production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art 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 paying any creative work.

[0027] Figure 1This is a comparison chart of discharge curves of the pure graphite scheme for the negative electrode and the graphite doped with 5% silicon material provided in the embodiment of the present application;

[0028] Figure 2 This is a comparison chart of discharge curves of the negative electrode pure graphite material solution and the graphite doped with 12% silicon material provided in the embodiment of the present application;

[0029] Figure 3 This is a discharge curve comparison diagram of the negative electrode graphite doped with 5% silicon material and the graphite doped with 12% silicon material provided in the embodiment of the present application;

[0030] Figure 4 It is a discharge curve comparison diagram of the negative electrode pure graphite, the negative electrode graphite doped with 5% silicon material, and the graphite doped with 12% silicon material provided in the embodiment of the present application;

[0031] Figure 5 This is a discharge curve comparison diagram of the positive electrode pure ternary material solution and the ternary 5% lithium iron phosphate doped material provided in the embodiment of the present application. DETAILED DESCRIPTION

[0032] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly understood, the present application is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0033] In this application, the term "and / or" describes the association relationship of associated objects, indicating that there may be three relationships. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. A and B can be singular or plural. The character " / " generally indicates that the associated objects are in an "or" relationship.

[0034] In this application, "at least one" means one or more, and "plurality" means two or more. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single items or plural items. For example, "at least one of a, b, or c", or "at least one of a, b, and c" can all mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, c can be single or multiple, respectively.

[0035] It should be understood that in the various embodiments of the present application, the size of the serial numbers of the above-mentioned processes does not mean the order of execution, some or all of the steps can be executed in parallel or sequentially, and the execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0036] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a", "an" and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.

[0037] The weight of the relevant components mentioned in the embodiment description of the present application can not only refer to the specific content of each component, but also represent the proportional relationship between the weights of the components. Therefore, as long as the content of the relevant components is proportionally enlarged or reduced according to the embodiment description of the present application, it is within the scope disclosed in the embodiment description of the present application. Specifically, the mass in the embodiment description of the present application can be μg, mg, g, kg and other mass units known in the chemical industry.

[0038] The terms "first" and "second" are used only for descriptive purposes to distinguish objects such as substances from each other, and should not be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. For example, without departing from the scope of the embodiments of the present application, the first XX may also be referred to as the second XX, and similarly, the second XX may also be referred to as the first XX. Thus, features defined as "first" and "second" may explicitly or implicitly include one or more of the features.

[0039] A first aspect of an embodiment of the present application provides a method for optimizing the terminal pressure difference of a battery, comprising the following steps:

[0040] Performing siliconization treatment on the negative electrode material of the battery to obtain a silicon-containing negative electrode material, preparing a plurality of first cells to be tested with the silicon-containing negative electrode material, testing the voltage change of each first cell to be tested under different discharge rate conditions and calculating the maximum voltage difference between each first cell to be tested at the end of discharge, and determining the optimized content of the silicon-containing negative electrode material according to the maximum voltage difference;

[0041] or,

[0042] The positive electrode materials of the battery are subjected to diversified mixing treatment to obtain a multi-component mixed positive electrode material, and a number of second test cells are prepared with the multi-component mixed positive electrode material. The voltage change of each second test cell under different discharge rate conditions is tested and the maximum voltage difference between each second test cell at the end of discharge is calculated, and the optimized content of the multi-component mixed positive electrode material is determined according to the maximum pressure difference.

[0043] A first aspect of an embodiment of the present application provides a method for optimizing the terminal pressure difference of a battery, the optimization method comprising optimizing the negative electrode material by silicon-containing treatment to obtain a silicon-containing negative electrode material or optimizing the positive electrode material by diversified mixed treatment. Any of the above optimization methods can be used to more effectively reduce the slope of the terminal pressure difference curve of the battery, reduce the pressure difference between the battery cells at the end of discharge, and improve the overall performance and life of the battery; and the optimization method based on the original positive electrode material or negative electrode material can increase the combination success rate and combination inclusiveness, thereby improving the overall performance and life of the battery, and the operation process is simple and easy to implement, without the need for complex equipment and technical support, which is conducive to reducing production costs and improving production efficiency.

[0044] The optimization method provided in the embodiment of the present application is mainly to optimize the negative electrode material or the positive electrode material respectively. You can choose to optimize the negative electrode material or optimize the positive electrode material.

[0045] In some specific implementation aspects, the negative electrode material is optimized. The details are as follows:

[0046] S01. The negative electrode material of the battery is subjected to siliconization treatment to obtain a silicon-containing negative electrode material, and a plurality of first test cells are prepared with the silicon-containing negative electrode material.

[0047] S02. Testing the voltage change of each first cell to be tested under different discharge rate conditions and calculating the maximum voltage difference between each first cell to be tested at the end of discharge,

[0048] S03. Determine the optimized content of the silicon-containing negative electrode material based on the maximum pressure difference.

[0049] The negative electrode material is treated with silicon. Since the charging and discharging platform of silicon is higher than that of graphite, and the platform of silicon is a changing slope, the voltage platform of the whole battery at the end of the discharge curve changes after adding silicon. The more silicon is added, the smaller the slope at the end of the full electric curve, and the smaller the pressure difference after assembly, thus achieving an optimization effect.

[0050] In step S01, a negative electrode material of a battery is subjected to a siliconization treatment to obtain a silicon-containing negative electrode material, and a plurality of first battery cells to be tested are prepared using the silicon-containing negative electrode material.

[0051] In some embodiments, in the silicon-containing negative electrode material, the silicon material includes any one of ground silicon-carbon material, silicon-oxygen material, pre-treated silicon-oxygen material, deposited silicon-carbon material, metallic silicon material, and silicon monoxide. The silicon material is provided for mixing with the original negative electrode material of the battery.

[0052] In some embodiments, the step of subjecting the negative electrode material of the battery to siliconization to obtain the silicon-containing negative electrode material includes:

[0053] The silicon-containing negative electrode material is obtained by combining the silicon-containing material with the negative electrode material of the original battery by a layered addition method, or the silicon-containing material is obtained by combining the silicon-containing material with the negative electrode material of the original battery by a mixed addition method.

[0054] In some specific embodiments, the step of combining the silicon-containing material with the primary battery negative electrode material to obtain the silicon-containing negative electrode material by a layered addition method includes:

[0055] G01. Silicon-containing materials according to D 50 The particle size is divided into the first silicon-containing material and the second silicon-containing material, and the D of the first silicon-containing material 50 The particle size is larger than that of the second silicon-containing material D 50 Small particle size;

[0056] G02. The first silicon-containing material and the auxiliary material in the negative electrode material are mixed by a first process to obtain a first mixture, and the second silicon-containing material and the main material in the negative electrode material are mixed by a second process to obtain a second mixture;

[0057] G03. Blend the first mixture and the second mixture to prepare a silicon-containing negative electrode material.

[0058] In step G01, the silicon-containing material is 50 The particle size is divided into the first silicon-containing material and the second silicon-containing material, and the D of the first silicon-containing material 50 The particle size is larger than that of the second silicon-containing material D 50 Small particle size. 50 Using particle size as a standard, the silicon-containing material is divided into two types of particles with different particle sizes, mainly to mix with large particles or small particles in the original components of the negative electrode material, to ensure that large-particle silicon-containing materials and large-particle original component materials are mixed evenly, and small-particle silicon-containing materials and small-particle original component materials are mixed evenly.

[0059] In some embodiments, D of the first silicon-containing material 50 The particle size is larger than that of the second silicon-containing material D 50 The particle size is as small as 5 to 10 μm.

[0060] In step G02, the first silicon-containing material and the auxiliary material in the negative electrode material are subjected to a first mixing process to obtain a first mixture, and the second silicon-containing material and the main material in the negative electrode material are subjected to a second mixing process to obtain a second mixture.

[0061] In some embodiments, the auxiliary material includes at least one of a conductive agent and a binder. The auxiliary material is a conductive agent or a binder, and the particle size is relatively small, so the auxiliary material is first mixed with the first silicon-containing material with a relatively small particle size, and the components in the obtained first mixture are uniformly mixed. The method of the first mixing treatment includes but is not limited to stirring, and the purpose is to obtain a uniformly mixed first mixture.

[0062] In some embodiments, the main material includes graphite. The particle size of graphite is larger than that of the conductive agent / binder, so the second mixing process is first performed with the second silicon-containing material having a larger particle size, and the components in the obtained second mixture are uniformly mixed. The method of the second mixing process includes but is not limited to stirring, in order to obtain a uniformly mixed second mixture.

[0063] In step G03, the first mixture and the second mixture are blended to prepare a silicon-containing negative electrode material, wherein blending includes but is not limited to stirring, and it only needs to be mixed evenly.

[0064] In some specific embodiments,

[0065] In some embodiments, the step of combining the silicon-containing material with the original battery negative electrode material by a mixed addition method to obtain a silicon-containing negative electrode material includes: using a physical mixing method or a chemical deposition method to deposit silicon on the surface and inside of the original battery negative electrode material in a desired proportion to obtain a mixed material, which is also a composite material.

[0066] In step S02, the voltage variation of each first battery cell to be tested under different discharge rate conditions is tested and the maximum voltage difference between each first battery cell to be tested at the end of discharge is calculated.

[0067] The specific experimental method includes: grouping the battery cells of different schemes with the same scheme (capacity 20mAh, voltage 3mv, internal resistance 3mΩ), and then combining the modules into a battery pack with 10S1P in the same arrangement order, and then discharging the battery packs of each scheme at different rates, collecting the voltage changes of each battery cell, and sorting out the dynamic voltage data of each module. The voltage values ​​of different battery cells in the module under the same lower limit voltage are intercepted, and the difference between the maximum and minimum values ​​is the voltage difference of the module.

[0068] In step S03, the optimized content of the silicon-containing negative electrode material is determined according to the maximum pressure difference.

[0069] Through the data, we found that the more silicon content reference, the smaller the terminal voltage difference between the battery cells in the module. We also need to comprehensively consider the changes in the electrical performance of the battery cells after adding different silicon, and comprehensively select the optimal silicon addition content, because the more silicon content, the worse the cycle performance.

[0070] In some embodiments, the optimized content of silicon-containing negative electrode material is 2wt% to 15wt%. Since the charge and discharge platform of silicon is higher than that of graphite, the voltage platform at the end of the discharge curve of the whole battery changes after adding silicon. The more silicon is added, the smaller the slope at the end of the full electric curve, and the smaller the pressure difference after assembly. If the addition amount is less than 2%, the effect on the slope of the discharge curve is small. If the addition amount is greater than 15%, the effect on the battery cell cycle is large, and it is not suitable to add more because of the large expansion of silicon. In some specific embodiments, the optimized content of silicon-containing negative electrode material includes but is not limited to 2wt%, 2.5wt%, 3wt%, 3.5wt%, 4wt%, 4.5wt%, 5wt%, 5.5wt%, 6wt%, 6.5wt%, 7wt%, 7.5wt%, 8wt%, 8.5wt%, 9wt%, 9.5wt%, 10wt%, 10.5wt%, 11wt%, 11.5wt%, 12wt%, 12.5wt%, 13wt%, 13.5wt%, 14wt%, 14.5wt%, 15wt%.

[0071] In other specific implementations, the positive electrode material is optimized. The details are as follows:

[0072] H01. Perform diversified mixing on the positive electrode material of the battery to obtain a multi-component mixed positive electrode material, and prepare a plurality of second test cells with the multi-component mixed positive electrode material.

[0073] H02. Test the voltage change of each second cell under different discharge rate conditions and calculate the maximum voltage difference between each second cell at the end of discharge.

[0074] H03. Determine the optimal content of multi-component mixed positive electrode materials based on the maximum pressure difference.

[0075] The optimization treatment of positive electrode materials mainly refers to doping with lithium materials with platform curves that are quite different in order to improve the slope at the end of the curve.

[0076] In step H01, a plurality of mixed positive electrode materials are processed to obtain a plurality of mixed positive electrode materials, and a plurality of second cells to be tested are prepared with the plurality of mixed positive electrode materials.

[0077] In some embodiments, the step of performing diversified mixing treatment on the positive electrode material of the battery to obtain a multi-component mixed positive electrode material includes: providing multiple lithium-containing positive electrode materials, mixing the lithium-containing positive electrode materials with different platform curve voltage values ​​to obtain a multi-component mixed positive electrode material; wherein the voltage values ​​of the platform curves of different lithium-containing positive electrode materials subjected to the mixing treatment differ by ≥0.4V.

[0078] In some embodiments, the multi-component mixed positive electrode material is a mixture of at least one of lithium cobalt oxide, lithium manganese oxide, lithium nickel cobalt manganese oxide, and lithium nickel cobalt aluminum oxide and lithium iron phosphate.

[0079] In some specific embodiments, the multi-component mixed positive electrode material includes but is not limited to a mixture of lithium cobalt oxide and lithium iron phosphate, a mixture of lithium manganate and lithium iron phosphate, a mixture of nickel cobalt lithium manganate and lithium iron phosphate, a mixture of nickel cobalt aluminum oxide and lithium iron phosphate, a mixture of lithium cobalt oxide and lithium manganate and lithium iron phosphate, a mixture of lithium cobalt oxide and nickel cobalt lithium manganate and lithium iron phosphate, a mixture of lithium cobalt oxide and nickel cobalt aluminum oxide and lithium iron phosphate, a mixture of lithium manganate and nickel cobalt lithium manganate and lithium iron phosphate, a mixture of lithium manganate and nickel cobalt lithium manganate and lithium iron phosphate, a mixture of lithium manganate and nickel cobalt lithium aluminum oxide and lithium iron phosphate, and a mixture of nickel cobalt lithium manganate and nickel cobalt lithium aluminum oxide and lithium iron phosphate.

[0080] In step H02, the voltage change of each second battery cell to be tested under different discharge rate conditions is tested and the maximum voltage difference between each second battery cell to be tested at the end of discharge is calculated.

[0081] The specific experimental method includes: grouping the battery cells of different schemes with the same scheme (capacity 20mAh, voltage 3mv, internal resistance 3mΩ), and then combining the modules into a battery pack with 10S1P in the same arrangement order, and then discharging the battery packs of each scheme at different rates, collecting the voltage changes of each battery cell, and sorting out the dynamic voltage data of each module. The voltage values ​​of different battery cells in the module under the same lower limit voltage are intercepted, and the difference between the maximum and minimum values ​​is the voltage difference of the module.

[0082] In step H03, the optimized content of the multi-component mixed positive electrode material is determined according to the maximum pressure difference.

[0083] Through the data, we found that the more silicon content reference, the smaller the terminal voltage difference between the battery cells in the module. We also need to comprehensively consider the changes in the electrical performance of the battery cells after adding different silicon, and comprehensively select the optimal silicon addition content, because the more silicon content, the worse the cycle performance.

[0084] The following describes the invention in conjunction with specific embodiments.

[0085] Example 1

[0086] A method for optimizing the terminal pressure difference of a battery comprises the following steps:

[0087] Provide grinding silicon carbon material, and convert silicon-containing material into 50 The particle size is divided into the first silicon-containing material and the second silicon-containing material, and the D of the first silicon-containing material 50 The particle size is larger than that of the second silicon-containing material D 50The particle size is small; the first silicon-containing material is mixed with the conductive agent and the binder in the negative electrode material to obtain a first mixture, and the second silicon-containing material is mixed with the graphite in the negative electrode material to obtain a second mixture; the first mixture and the second mixture are blended to prepare a silicon-containing negative electrode material, wherein the total mass of the silicon negative electrode material is 100% and the mass percentage of silicon is 5%;

[0088] A number of first test cells are prepared with silicon-containing negative electrode materials. The specific preparation method is as follows: the synthesized silicon negative electrode material is mixed and stirred evenly with a binder, a conductive agent, and a solvent to form a slurry, which is then coated on a copper foil, rolled and slit into sheets, and then wound and assembled with the prepared positive electrode sheet, and then dried and injected with electrolyte, and then formed into a battery through processes such as formation, activation, and capacity division;

[0089] The battery cells of different schemes are grouped with the same scheme (capacity 20mAh, voltage 3mv, internal resistance 3mΩ), and then combined into a battery pack with 10S1P modules in the same arrangement order. Then, the battery packs of each scheme are discharged at different rates, and the voltage changes of each battery cell are collected. By sorting out the dynamic voltage data of each module, the voltage values ​​of different battery cells in the module under the same lower limit voltage are intercepted, and the difference between the maximum and minimum values ​​is the voltage difference of the module.

[0090] Example 2

[0091] A method for optimizing the terminal pressure difference of a battery comprises the following steps:

[0092] Provide grinding silicon carbon material, and convert silicon-containing material into 50 The particle size is divided into the first silicon-containing material and the second silicon-containing material, and the D of the first silicon-containing material 50 The particle size is larger than that of the second silicon-containing material D 50 The particle size is small; the first silicon-containing material is mixed with the conductive agent and the binder in the negative electrode material to obtain a first mixture, and the second silicon-containing material is mixed with the graphite in the negative electrode material to obtain a second mixture; the first mixture and the second mixture are blended to prepare a silicon-containing negative electrode material, wherein the total mass of the silicon negative electrode material is 100% and the mass percentage of silicon is 10%;

[0093] A number of first test cells are prepared with silicon-containing negative electrode materials. The specific preparation method is as follows: the synthesized silicon negative electrode material is mixed and stirred evenly with a binder, a conductive agent, and a solvent to form a slurry, which is then coated on a copper foil, rolled and slit into sheets, and then wound and assembled with the prepared positive electrode sheet, and then dried and injected with electrolyte, and then formed into a battery through processes such as formation, activation, and capacity division;

[0094] The battery cells of different schemes are grouped with the same scheme (capacity 20mAh, voltage 3mv, internal resistance 3mΩ), and then combined into a battery pack with 10S1P modules in the same arrangement order. Then, the battery packs of each scheme are discharged at different rates, and the voltage changes of each battery cell are collected. By sorting out the dynamic voltage data of each module, the voltage values ​​of different battery cells in the module under the same lower limit voltage are intercepted, and the difference between the maximum and minimum values ​​is the voltage difference of the module.

[0095] Example 3

[0096] A method for optimizing the terminal pressure difference of a battery comprises the following steps:

[0097] Provide grinding silicon carbon material, and convert silicon-containing material into 50 The particle size is divided into the first silicon-containing material and the second silicon-containing material, and the D of the first silicon-containing material 50 The particle size is larger than that of the second silicon-containing material D 50 The particle size is small; the first silicon-containing material is mixed with the conductive agent and the binder in the negative electrode material to obtain a first mixture, and the second silicon-containing material is mixed with the graphite in the negative electrode material to obtain a second mixture; the first mixture and the second mixture are blended to prepare a silicon-containing negative electrode material, wherein the total mass of the silicon negative electrode material is 100% and the mass percentage of silicon is 12%;

[0098] A number of first test cells are prepared with silicon-containing negative electrode materials. The specific preparation method is as follows: the synthesized silicon negative electrode material is mixed and stirred evenly with a binder, a conductive agent, and a solvent to form a slurry, which is then coated on a copper foil, rolled and slit into sheets, and then wound and assembled with the prepared positive electrode sheet, and then dried and injected with electrolyte, and then formed into a battery through processes such as formation, activation, and capacity division;

[0099] The battery cells of different schemes are grouped with the same scheme (capacity 20mAh, voltage 3mv, internal resistance 3mΩ), and then combined into a battery pack with 10S1P modules in the same arrangement order. Then, the battery packs of each scheme are discharged at different rates, and the voltage changes of each battery cell are collected. By sorting out the dynamic voltage data of each module, the voltage values ​​of different battery cells in the module under the same lower limit voltage are intercepted, and the difference between the maximum and minimum values ​​is the voltage difference of the module.

[0100] Example 4

[0101] A method for optimizing the terminal pressure difference of a battery comprises the following steps:

[0102] Providing a mixture of lithium cobalt oxide and lithium iron phosphate, and mixing lithium-containing positive electrode materials having voltage values ​​of different platform curves to obtain a multi-component mixed positive electrode material;

[0103] The positive electrode material of the battery is subjected to a diversified mixing process to obtain a multi-component mixed positive electrode material, and a plurality of second test cells are prepared with the multi-component mixed positive electrode material. The specific preparation method is as follows: the synthesized multi-component mixed positive electrode material is mixed and stirred evenly with a binder, a conductive agent, and a solvent to form a slurry, which is then coated on an aluminum foil, rolled and slit into sheets, and then wound and assembled with the prepared negative electrode sheet, and then dried and injected with an electrolyte, and then subjected to formation, activation, capacity division, and other processes to form a battery;

[0104] The voltage change of each second cell to be tested under different discharge rate conditions is tested and the maximum voltage difference between each second cell to be tested at the end of discharge is calculated. The cells of different schemes are grouped with the same scheme (capacity 20mAh, voltage 3mv, internal resistance 3mΩ), and then the modules are combined into a battery pack with 10S1P in the same arrangement order. Then, the battery packs of each scheme are discharged at different rates, and the voltage change of each cell is collected. By sorting out the dynamic voltage data of each module, the voltage values ​​of different cells in the module under the same lower limit voltage are intercepted, and the difference between the maximum and minimum values ​​is the voltage difference of the module.

[0105] According to the maximum voltage difference and the influence on the electrical performance, the optimal range of the content of lithium cobalt oxide and lithium iron phosphate is determined to be 5% of the optimal lithium iron doping amount.

[0106] Example 5

[0107] A method for optimizing the terminal pressure difference of a battery comprises the following steps:

[0108] Providing a mixture of lithium manganate and lithium iron phosphate, and mixing lithium-containing positive electrode materials having voltage values ​​of different platform curves to obtain a multi-component mixed positive electrode material;

[0109] The positive electrode material of the battery is subjected to a diversified mixing process to obtain a multi-component mixed positive electrode material, and a plurality of second test cells are prepared with the multi-component mixed positive electrode material. The specific preparation method is as follows: the synthesized multi-component mixed positive electrode material is mixed and stirred evenly with a binder, a conductive agent, and a solvent to form a slurry, which is then coated on an aluminum foil, rolled and slit into sheets, and then wound and assembled with the prepared negative electrode sheet, and then dried and injected with an electrolyte, and then subjected to formation, activation, capacity division, and other processes to form a battery;

[0110] Test the voltage change of each second cell to be tested under different discharge rates and calculate the maximum voltage difference between each second cell to be tested at the end of discharge. Test the voltage change of each second cell to be tested under different discharge rates and calculate the maximum voltage difference between each second cell to be tested at the end of discharge. Group the cells of different schemes with the same scheme (capacity 20mAh, voltage 3mv, internal resistance 3mΩ), and then combine the modules of 10S1P into a battery pack with the same arrangement order. Then discharge the battery packs of each scheme at different rates, collect the voltage change of each cell, sort out the dynamic voltage data of each module, intercept the voltage values ​​of different cells in the module under the same lower limit voltage, and take the difference between the maximum and minimum values ​​as the voltage difference of the module.

[0111] According to the maximum pressure difference, the content of lithium manganese oxide and lithium iron phosphate is determined to be the optimal lithium iron doping amount of 4%.

[0112] Example 6

[0113] A method for optimizing the terminal pressure difference of a battery comprises the following steps:

[0114] Providing a mixture of lithium cobalt oxide, lithium manganese oxide and lithium iron phosphate, and mixing lithium-containing positive electrode materials with voltage values ​​of different platform curves to obtain a multi-component mixed positive electrode material;

[0115] The positive electrode material of the battery is subjected to a diversified mixing process to obtain a multi-component mixed positive electrode material, and a plurality of second test cells are prepared with the multi-component mixed positive electrode material. The specific preparation method is as follows: the synthesized multi-component mixed positive electrode material is mixed and stirred evenly with a binder, a conductive agent, and a solvent to form a slurry, which is then coated on an aluminum foil, rolled and slit into sheets, and then wound and assembled with the prepared negative electrode sheet, and then dried and injected with an electrolyte, and then subjected to formation, activation, capacity division, and other processes to form a battery;

[0116] Test the voltage change of each second cell to be tested under different discharge rates and calculate the maximum voltage difference between each second cell to be tested at the end of discharge, test the voltage change of each second cell to be tested under different discharge rates and calculate the maximum voltage difference between each second cell to be tested at the end of discharge, test the voltage change of each second cell to be tested under different discharge rates and calculate the maximum voltage difference between each second cell to be tested at the end of discharge, group the cells of different schemes with the same scheme (capacity 20mAh, voltage 3mv, internal resistance 3mΩ), and then combine the modules of 10S1P into a battery pack with the same arrangement order, and then discharge the battery packs of each scheme at different rates, collect the voltage change of each cell, sort out the dynamic voltage data of each module, intercept the voltage values ​​of different cells in the module under the same lower limit voltage, and take the difference between the maximum and minimum values ​​as the voltage difference of the module.

[0117] According to the maximum pressure difference, the content of lithium cobalt oxide, lithium manganese oxide and lithium iron phosphate is determined to be the optimal lithium iron content of 2%, and the proportion of lithium cobalt oxide and lithium manganese oxide can be matched arbitrarily.

[0118] Comparative Example 1

[0119] A method for optimizing the terminal pressure difference of a battery comprises the following steps:

[0120] Pure graphite is used as the negative electrode material, and a plurality of first test cells are prepared with the pure graphite negative electrode material. The specific preparation method is as follows: the pure graphite negative electrode material is mixed and stirred evenly with a binder, a conductive agent, and a solvent to form a slurry, which is then coated on a copper foil, rolled and slit into sheets, and then wound and assembled with the prepared positive electrode sheet, and then dried and then injected with electrolyte, and then formed into a battery through processes such as formation, activation, and capacity division;

[0121] The battery cells of different schemes are grouped with the same scheme (capacity 20mAh, voltage 3mv, internal resistance 3mΩ), and then combined into a battery pack with 10S1P modules in the same arrangement order. Then, the battery packs of each scheme are discharged at different rates, and the voltage changes of each battery cell are collected. By sorting out the dynamic voltage data of each module, the voltage values ​​of different battery cells in the module under the same lower limit voltage are intercepted, and the difference between the maximum and minimum values ​​is the voltage difference of the module.

[0122] Comparative Example 2

[0123] A method for optimizing the terminal pressure difference of a battery comprises the following steps:

[0124] A plurality of second cells to be tested are prepared using the pure ternary material as the positive electrode material. The specific preparation method is as follows: the positive electrode material of the pure ternary material is mixed and stirred evenly with a binder, a conductive agent, and a solvent to form a slurry, which is then coated on an aluminum foil, rolled and slit into sheets, and then wound and assembled with the prepared negative electrode sheet, and then dried and injected with electrolyte, and then formed into a battery through processes such as formation, activation, and capacity division.

[0125] Test the voltage change of each second cell to be tested under different discharge rates and calculate the maximum voltage difference between each second cell to be tested at the end of discharge. Test the voltage change of each second cell to be tested under different discharge rates and calculate the maximum voltage difference between each second cell to be tested at the end of discharge. Group the cells of different schemes with the same scheme (capacity 20mAh, voltage 3mv, internal resistance 3mΩ), and then combine the modules of 10S1P into a battery pack with the same arrangement order. Then discharge the battery packs of each scheme at different rates, collect the voltage change of each cell, sort out the dynamic voltage data of each module, intercept the voltage values ​​of different cells in the module under the same lower limit voltage, and take the difference between the maximum and minimum values ​​as the voltage difference of the module.

[0126] Property Test

[0127] (1) The 10S1P battery was used as a control group, and the maximum voltage, minimum voltage, and voltage difference of the batteries of Example 1, Example 2, and Example 4 were measured respectively.

[0128] (2) Further analyze the discharge curves of the batteries of Example 1 and Comparative Example 1 at room temperature 1C, the discharge curves of the batteries of Example 3 and Comparative Example 1 at room temperature 1C, the discharge curves of the batteries of Example 1 and Example 3 at room temperature 1C, the discharge curves of the batteries of Example 1, Example 3 and Comparative Example 1 at room temperature 1C, and the discharge curves of the batteries of Example 4 and Comparative Example 2 at room temperature 1C.

[0129] Results Analysis

[0130] (1) The 10S1P battery was used as a control group, and the maximum voltage, minimum voltage and voltage difference of the batteries of Example 1, Example 2 and Example 4 were measured respectively. As shown in Table 1, the maximum voltage and minimum voltage were measured under the conditions of discharge current of 0.5C, 1C, 3C and 5C, and the voltage difference was calculated. It can be obtained that under the condition of 0.5C, the voltage difference of the control group, Example 1, Example 2 and Example 4 was 642.3, 300.1, 263.2 and 198.9 respectively; Under 1C conditions, the voltage differences of the control group, Example 1, Example 2, and Example 4 are 558.7, 192.2, 156.6, and 183.3, respectively; under 3C conditions, the voltage differences of the control group, Example 1, Example 2, and Example 4 are 390.6, 141.6, 122.4, and 179.2, respectively; under 5C conditions, the voltage differences of the control group, Example 1, Example 2, and Example 4 are 178.9, 43.2, 42.83, and 103.9, respectively. It can be seen that under different discharge current conditions, the voltage difference of the battery provided by each embodiment is smaller than that of the battery provided by the control group, which can improve the overall performance of the battery.

[0131] Table 1

[0132]

[0133]

[0134] (2) Further analyze the performance of each battery.

[0135] The discharge curves of the batteries of Example 1 and Comparative Example 1 at room temperature and 1C are as follows: Figure 1 As shown, it can be seen that the curve of the battery in Example 1 is slowly decreasing, the voltage change is relatively stable, and the voltage difference is small.

[0136] The discharge curves of the batteries of Example 3 and Comparative Example 1 at room temperature and 1C are as follows: Figure 2 As shown, it can be seen that the curve of the battery in Example 3 is slowly decreasing, the voltage change is relatively stable, and the voltage difference is small.

[0137] The discharge curves of the batteries of Example 1 and Example 3 at room temperature 1C are as follows: Figure 3 As shown, it can be seen that the curves of the batteries of Example 1 and Example 3 both show a slow decline, the voltage change is relatively stable, and the voltage difference is small.

[0138] The discharge curves of the batteries of Example 1, Example 3 and Comparative Example 1 at room temperature and 1C are as follows: Figure 4 As shown, it can be seen that the curves of the batteries of Example 1 and Example 3 both show a slow decline, the voltage change is relatively stable, and the voltage difference is small.

[0139] Discharge curves of the batteries of Example 4 and Comparative Example 2 at room temperature 1C Figure 5 As shown, it can be seen that the final capacity retention rate of the battery of Example 4 is relatively high, approximately 97%, while the final capacity retention rate of the battery of Comparative Example 2 is relatively low, at 93%.

[0140] In summary, an embodiment of the present application provides a method for optimizing the terminal pressure difference of a battery, which includes optimizing the negative electrode material by silicon-containing treatment to obtain a silicon-containing negative electrode material or optimizing the positive electrode material by diversified mixed treatment. Any of the above optimization methods can be used to more effectively reduce the slope of the terminal pressure difference curve of the battery, reduce the pressure difference between the battery cells at the end of discharge, and improve the overall performance and life of the battery; and the optimization method based on the original positive electrode material or negative electrode material can increase the combination success rate and combination inclusiveness, thereby improving the overall performance and life of the battery, and the operation process is simple and easy to implement, without the need for complex equipment and technical support, which is conducive to reducing production costs and improving production efficiency.

[0141] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A method for optimizing the terminal pressure difference of a battery, characterized in that: The steps include: Performing siliconization treatment on the negative electrode material of the battery to obtain a silicon-containing negative electrode material, preparing a plurality of first cells to be tested with the silicon-containing negative electrode material, testing the voltage change of each of the first cells to be tested under different discharge rate conditions and calculating the maximum voltage difference between each of the first cells to be tested at the end of discharge, and determining the optimized content of the silicon-containing negative electrode material according to the maximum voltage difference; or, The positive electrode material of the battery is subjected to a diversified mixing process to obtain a multi-component mixed positive electrode material, and a plurality of second test cells are prepared with the multi-component mixed positive electrode material. The voltage change of each second test cell under different discharge rate conditions is tested, and the maximum voltage difference between each second test cell at the end of discharge is calculated. According to the maximum pressure difference, the optimized content of the multi-component mixed positive electrode material is determined.

2. The method for optimizing the terminal pressure difference of a battery according to claim 1, characterized in that: In the silicon-containing negative electrode material, the silicon material includes any one of ground silicon-carbon material, silicon-oxygen material, pre-treated silicon-oxygen material, deposited silicon-carbon material, metallic silicon material, and silicon monoxide.

3. The method for optimizing the terminal pressure difference of a battery according to claim 1, characterized in that: The step of subjecting the negative electrode material of the battery to siliconization to obtain the silicon-containing negative electrode material comprises: The silicon-containing negative electrode material is obtained by combining the silicon-containing material with the negative electrode material of the original battery by a layered addition method, or the silicon-containing material is obtained by combining the silicon-containing material with the negative electrode material of the original battery by a mixed addition method.

4. The method for optimizing the terminal pressure difference of a battery according to claim 3, characterized in that: The step of combining the silicon-containing material with the negative electrode material of the primary battery by a layered addition method to obtain the silicon-containing negative electrode material comprises: The silicon-containing material is 50 The particle size is divided into a first silicon-containing material and a second silicon-containing material, and the D of the first silicon-containing material 50 The particle size is greater than that of the second silicon-containing material D 50 Small particle size; The first silicon-containing material is mixed with the auxiliary material in the negative electrode material to obtain a first mixture, and the second silicon-containing material is mixed with the main material in the negative electrode material to obtain a second mixture; The first mixture and the second mixture are blended to prepare a silicon-containing negative electrode material.

5. The method for optimizing the terminal pressure difference of a battery according to claim 4, characterized in that: The auxiliary material includes at least one of a conductive agent and a binder; and / or, The main material includes graphite.

6. The method for optimizing the terminal pressure difference of a battery according to claim 4, characterized in that: The D of the first silicon-containing material 50 The particle size is greater than that of the second silicon-containing material D 50 The particle size is as small as 5 to 10 μm.

7. The method for optimizing the terminal pressure difference of a battery according to claim 3, characterized in that: In the step of combining the silicon-containing material with the primary battery negative electrode material by a mixed addition method to obtain the silicon-containing negative electrode material, a physical mixing method or a chemical deposition method is used to deposit silicon on the surface and inside of the primary battery negative electrode material in a desired proportion to obtain a mixed material.

8. The method for optimizing the terminal pressure difference of a battery according to claim 1, characterized in that: The optimized content of the silicon-containing negative electrode material is 2 wt % to 15 wt %.

9. The method for optimizing the terminal pressure difference of a battery according to claim 1, characterized in that: The step of performing diversified mixing treatment on the positive electrode materials of the battery to obtain a multi-component mixed positive electrode material includes: providing multiple lithium-containing positive electrode materials, mixing the lithium-containing positive electrode materials with voltage values ​​of different platform curves to obtain a multi-component mixed positive electrode material; wherein the voltage values ​​of the platform curves of different lithium-containing positive electrode materials subjected to the mixing treatment differ by ≥0.4V.

10. The method for optimizing the terminal pressure difference of a battery according to claim 9, characterized in that: The multi-component mixed positive electrode material is a mixture of at least one of lithium cobalt oxide, lithium manganese oxide, lithium nickel cobalt manganese oxide, and lithium nickel cobalt aluminum oxide and lithium iron phosphate.

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