Battery and electric device

Abstract

An electric device, which comprises a battery. A negative electrode sheet of the battery comprises a negative electrode active material. The negative electrode sheet satisfies: 5≤k*D3*D2*η2 / [γ*D0*D1]≤15, wherein η is the OI value of the negative electrode sheet, D0 is the highest-frequency pore diameter, with the unit thereof being nm; D1 is the Dv50 of the negative electrode active material, with the unit thereof being μm; D2 is the most probable pore size of the negative electrode sheet, with the unit thereof being nm; D3 is the average pore diameter, with the unit thereof being nm; and γ is the N / P ratio of the battery, and k=1000.

Description

Batteries and electrical equipment

[0001] Cross-references to related applications

[0002] This application claims priority to Chinese patent application filed on November 28, 2024, with application number 202411731045.6 and entitled "Batteries and Electrical Devices", the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates to the field of battery technology, and in particular to a battery and an electrical device. Background Technology

[0004] During the electrode fabrication process, the active material in the coated electrode has a high porosity. Therefore, the electrode needs to be rolled and pressed to increase the compaction density and thus improve the battery energy density. However, after the compaction density is increased, the effective diffusion of the electrolyte in the electrode is easily hindered during battery fabrication, leading to an increase in polarization resistance and thus affecting the battery's fast-charging performance.

[0005] Public content

[0006] This disclosure aims to at least address one of the technical problems existing in the prior art. Therefore, the first objective of this disclosure is to provide a battery in which the electrolyte wetting effect of the negative electrode is good and does not hinder ion diffusion, so that the negative electrode can meet the battery's fast-charging performance requirements.

[0007] The second objective of this disclosure is to provide an electrical device.

[0008] According to a battery embodiment of the first aspect of this disclosure, the battery includes a negative electrode sheet, the negative electrode sheet includes a negative electrode active material, and the negative electrode sheet satisfies: 5 ≤ k * D3 * D2 * η 2 / [γ*D0*D1]≤15; where η is the OI value of the negative electrode, D0 is the most frequent pore size of the negative electrode in nm, D1 is the Dv50 of the negative electrode active material in μm, D2 is the most probable pore size of the negative electrode in nm, D3 is the average pore diameter of the negative electrode in nm, γ is the N / P ratio of the battery, and k=1000.

[0009] Through extensive experiments, the inventors of this disclosure discovered that by controlling the parameters of the negative electrode in the battery to satisfy the above formula, the pore structure and tortuosity of the negative electrode can be fully optimized, resulting in good electrolyte wetting effect and no obstruction of ion diffusion, so that the negative electrode can meet the fast charging performance of the battery.

[0010] According to some embodiments of this disclosure, the negative electrode sheet satisfies: 9 ≤ k * D3 * D2 * η 2 / [γ*D0*D1]≤15.

[0011] According to some embodiments of this disclosure, D0 satisfies: 10nm≤D0≤150nm; and / or γ satisfies: 1.01≤γ≤1.5; and / or D1 satisfies: 5μm≤D1≤20μm; and / or D2 satisfies: 0.5nm≤D2≤5nm; and / or D3 satisfies: 15nm≤D3≤30nm; and / or η satisfies: 2≤η≤20.

[0012] According to some embodiments of this disclosure, D0 satisfies: 20nm≤D0≤35nm; and / or γ satisfies: 1.01≤γ≤1.2; and / or D1 satisfies: 10μm≤D1≤15μm; and / or D2 satisfies: 1.5nm≤D2≤2nm; and / or D3 satisfies: 20nm≤D3≤25nm; and / or η satisfies: 8≤η≤15.

[0013] According to some embodiments of this disclosure, the content of the negative electrode active material in the negative electrode sheet is 80wt% to 98wt%.

[0014] According to some embodiments of this disclosure, the negative electrode active material includes at least one of hard carbon, artificial graphite, natural graphite, silicon-based materials, tin-based materials, and lithium titanate.

[0015] According to some embodiments of this disclosure, the silicon-based material includes at least one of elemental silicon, silicon oxide, silicon alloy, and composite silicon; and / or the tin-based material includes at least one of tin oxide and tin alloy.

[0016] According to some embodiments of this disclosure, the negative electrode further includes a conductive agent, and the content of the conductive agent in the negative electrode is 0.1 wt% to 10 wt%.

[0017] According to some embodiments of this disclosure, the conductive agent includes at least one of conductive carbon black, carbon nanotubes, graphene, conductive graphite, and carbon fiber.

[0018] An electrical device according to a second aspect of the present disclosure includes at least one battery according to any of the first aspects of the present disclosure described above.

[0019] Additional aspects and advantages of this disclosure will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this disclosure. Detailed Implementation

[0020] The following describes a battery according to an embodiment of the first aspect of this disclosure.

[0021] Specifically, the battery includes a negative electrode, which includes a negative electrode active material, and the negative electrode satisfies the following:

[0022] 5≤k*D3*D2*η 2 / [γ*D0*D1]≤15;

[0023] Where η is the OI (orientation index) value of the negative electrode; D0 is the most frequent pore size of the negative electrode, in nm; D1 is the Dv50 of the negative electrode active material, in μm; D2 is the most probable pore size of the negative electrode, in nm; D3 is the average pore diameter of the negative electrode, in nm; γ is the N / P (Negative / Positive) ratio of the battery (or "negative electrode capacity / positive electrode capacity"); k = 1000.

[0024] The above-mentioned negative electrode sheets are assembled into a battery, which can meet the needs of fast charging performance and energy density balance.

[0025] During battery discharge, the negative electrode active material undergoes an oxidation reaction, releasing electrons. These electrons generate current through an external circuit. Therefore, the choice of negative electrode active material directly affects the battery's performance, such as energy density, cycle life, safety, and cost.

[0026] Where η is the OI value of the negative electrode, which is usually used to describe the degree of orderliness of the arrangement of the negative electrode active material in the negative electrode. OI value = C004 / C110, where C004 is the peak area of ​​the 004 characteristic diffraction peak and C110 is the peak area of ​​the 110 characteristic diffraction peak. Specifically, the OI value is the ratio of the peak area of ​​the characteristic diffraction peak of the negative electrode active material (e.g., graphite) (004) surface to the peak area of ​​the characteristic diffraction peak of the negative electrode active material (110) surface, obtained by XRD (X-ray Diffraction) testing on the surface of the negative electrode. The principle of OI value testing is as follows: When the diffraction pattern of the negative electrode sample is tested, the diffraction peaks of the (004) plane and (110) plane of the negative electrode active material can be obtained respectively. The stronger the intensity of the (004) peak, the more particles of the (004) crystal plane are parallel to the current collector of the negative electrode. The OI value, which is the ratio of the intensity (or integrated area) of the diffraction peak of the (004) crystal plane to the intensity (or integrated area) of the diffraction peak of the (110) crystal plane, can be used to measure the orientation of the negative electrode active material in the negative electrode. The higher the OI value, the more negative electrode active materials in the electrode are parallel to the current collector, and the higher the degree of order of the arrangement of the negative electrode active materials in the negative electrode.

[0027] D0 is the most frequent pore size of the negative electrode. This pore size is the pore size that appears most frequently in the 5nm-200nm range in the pore size distribution of the negative electrode. The pore size of the electrode is analyzed using the BJH (Barrett-Joyner-Halenda) method to obtain the logarithmic distribution curve of the (desorption) differential integral pore volume pore size (the test principle can be found in the national standards GB-T19587-2017 and GB / T21650.2-2008). The peak value of the 5nm-200nm segment on the logarithmic distribution curve of the (desorption) differential integral pore volume pore size corresponds to the most frequent pore size.

[0028] D1 is the Dv50 of the negative electrode active material, which is the volume average particle size in μm. The negative electrode active material is tested using a Malvern particle size analyzer. The test principle refers to the national standard GB / T41949-2022. In other words, the particle size test is the particle size value that reaches 50% of the cumulative volume distribution percentage.

[0029] D2 is the most probable pore size of the negative electrode, that is, the pore size that appears most frequently in the pore size distribution. The electrode is analyzed using the BJH method to obtain the differential and integral pore volume pore size distribution curve of the electrode. The testing principle can be found in the national standards GB-T19587-2017 and GB / T21650.2-2008. The pore size corresponding to the peak value of the differential and integral pore volume pore size distribution curve is the most probable pore size value, and the unit is nm.

[0030] D3 represents the average pore diameter of the negative electrode, calculated from the cumulative total pore volume and the cumulative specific surface area within the pores using the BJH desorption method. The average pore diameter affects electrolyte wettability, ion transport efficiency, and battery cycle performance. The BJH method is used to analyze the pore size of the negative electrode; the testing principle can be found in national standards GB-T19587-2017 and GB / T21650.2-2008. The average straight pore diameter is calculated as: average straight pore diameter = 4 × cumulative pore volume / cumulative pore specific surface area, in nm.

[0031] γ represents the N / P ratio of a battery, also known as the negative-to-positive ratio or the negative electrode / positive electrode ratio. It refers to the capacity ratio of the negative electrode material to the positive electrode material in the battery. The N / P ratio is determined by calculating the capacity ratio of the positive electrode (P) to the negative electrode (N). A higher N / P ratio can prevent complete delithiation of the positive electrode material during charging, thus reducing the risk of thermal runaway. However, it can lead to a decrease in the battery's energy density because excessive negative electrode material occupies internal space, reducing the overall energy storage capacity. Conversely, a lower N / P ratio can increase energy density, but may sacrifice some safety. Therefore, by optimizing the N / P ratio, it is possible to achieve higher energy density and longer cycle life while ensuring battery safety.

[0032] In summary, a suitable pore size distribution is crucial for ensuring good electrolyte wetting, efficient lithium-ion transport, and improving battery cycle stability and energy density. Smaller pore sizes may contribute to higher energy density, while larger pore sizes may contribute to higher power density, providing better electrolyte wetting and faster ion transport. Simultaneously, a suitable N / P ratio can achieve higher energy density and longer cycle life while ensuring battery safety. This can be achieved by adjusting the ranges of η, D0, D1, D2, D3, γ, and k to achieve k*D3*D2*η. 2 The value of / [γ*D0*D1] is between 5 and 15, which can optimize the pore structure and tortuosity of the electrode, so that the electrolyte wetting effect of the negative electrode is good and does not hinder ion diffusion.

[0033] According to the battery of the present disclosure, by limiting the parameters of the negative electrode sheet, the pore structure and tortuosity of the negative electrode sheet can be optimized, the structure of the negative electrode sheet can be fully optimized, the electrolyte wetting effect of the negative electrode sheet is good and does not hinder ion diffusion, so that the negative electrode sheet can meet the needs of battery fast charging performance and energy density balance.

[0034] Preferably, 9 ≤ k * D3 * D2 * η 2 / [γ*D0*D1]≤15. This ensures that the calculated values ​​of η, D0, D1, D2, D3, γ, and k are between 9 and 15, resulting in better performance constraints for the negative electrode and further guaranteeing its electrolyte wetting effect and ion diffusion capability.

[0035] According to some embodiments of this disclosure, D0 satisfies: 10nm ≤ D0 ≤ 150nm. The most common pore size in the pore size distribution of the negative electrode is more reasonable, avoiding pore sizes that are too large or too small and cannot meet the needs of the negative electrode.

[0036] γ satisfies: 1.01≤γ≤1.5. The above N / P ratio of the battery is reasonable, which is beneficial to ensuring battery safety, and at the same time, it is beneficial to achieve higher energy density and longer cycle life.

[0037] D1 satisfies: 5μm≤D1≤20μm. The average particle size of the negative electrode active material is relatively reasonable, which is conducive to fully leveraging the role of the negative electrode active material in improving the battery's energy density, cycle life, safety, and reducing costs.

[0038] D2 satisfies: 0.5nm ≤ D2 ≤ 5nm. The most probable pore size of the negative electrode is relatively reasonable, which is beneficial to improving the battery's power density while increasing its energy density.

[0039] D3 satisfies the condition: 15nm ≤ D3 ≤ 30nm. The limitation on the average pore diameter is reasonable, which fully improves the wettability of the electrolyte, the ion transport efficiency, and the cycle performance of the battery.

[0040] η satisfies: 2≤η≤20. The constraint on η is reasonable, which makes the arrangement of the negative electrode active material more orderly, ensuring good electronic conductivity and thermal stability of the negative electrode sheet, thereby potentially improving the performance of the battery.

[0041] The above-mentioned limits on the ranges of D0, γ, D1, D2, D3 and η are reasonable. Under the premise of ensuring the optimal performance of each parameter, D0, γ, D1, D2, D3 and η satisfy the limits of the above formula, which is beneficial to the electrolyte wetting effect of the negative electrode and does not hinder ion diffusion.

[0042] D0 can be 10nm, 20nm, 50nm, 100nm, 120nm, or 150nm, but is not limited to these.

[0043] γ can be 1.01, 1.12, 1.2, or 1.5, but is not limited to these values.

[0044] D1 can be 5μm, 10μm, 14μm, 17μm, or 20μm, but is not limited to these.

[0045] D2 can be 0.5nm, 1.8nm, 2nm, 3nm, 4.0nm, or 5nm. But it is not limited to these.

[0046] D3 can be 16nm, 20nm, 22nm, or 24nm, but it is not limited to these.

[0047] η can be 2, 5, 7, 10, 15, 17, or 20. But it is not limited to these.

[0048] Preferably, D0 satisfies: 20nm ≤ D0 ≤ 35nm; and / or γ satisfies: 1.01 ≤ γ ≤ 1.2; and / or D1 satisfies: 10μm ≤ D1 ≤ 15μm; and / or D2 satisfies: 1.5nm ≤ D2 ≤ 2nm; and / or D3 satisfies: 20nm ≤ D3 ≤ 25nm; and / or η satisfies: 8 ≤ η ≤ 15. Therefore, the defined ranges of D0, γ, D1, D2, D3, and η are more optimal, making k*D3*D2*η 2 The range of / [γ*D0*D1] meets the requirements of the negative electrode, while D 00 The parameters γ, D1, D2, D3 and η are also more superior, which helps to further ensure the quality of the negative electrode and make the battery using the above negative electrode perform better.

[0049] According to some embodiments of this disclosure, the content of negative electrode active material in the negative electrode sheet is 80wt% to 98wt%. The loading of negative electrode active material is relatively reasonable, thereby making the current distribution inside the negative electrode sheet more uniform, and thus improving the overall performance of the battery.

[0050] Furthermore, the negative electrode active material includes at least one of the following: hard carbon, artificial graphite, natural graphite, silicon-based materials, tin-based materials, and lithium titanate. Hard carbon, in particular, possesses high mechanical strength and exhibits excellent electrochemical performance at low temperatures, making it suitable for batteries used in cold environments. This contributes to extending battery life in low-temperature conditions and enriching battery operating conditions. Artificial graphite can store a large number of lithium ions, thus providing high energy density. Furthermore, artificial graphite maintains stable electrochemical performance under high-speed charge-discharge conditions, meeting the demands of rapid battery charging. Natural graphite, as an excellent electrical conductor, can effectively transport electrons, contributing to improved battery electrochemical performance. Compared to artificial graphite, the production process of natural graphite is relatively simple, eliminating the need for high-temperature graphitization, resulting in lower costs. Silicon-based materials have high theoretical capacity and energy density, enabling batteries to store more energy. Tin-based materials possess high theoretical capacity and a moderate lithium intercalation potential, exhibiting relatively stable lithium-ion insertion and extraction during charge and discharge, reducing the risk of lithium dendrite formation and improving battery safety. Lithium titanate exhibits almost no volume change during lithium-ion insertion and extraction, a characteristic known as "zero strain." This stability contributes to improved battery cycle performance and overall lifespan. The high lithium titanate potential makes it less prone to lithium metal dendrite formation at the negative electrode, thus avoiding the risk of short circuits and enhancing battery safety. Furthermore, lithium titanate possesses a high lithium-ion diffusion coefficient, allowing for high-rate charge and discharge, making it ideal for applications requiring rapid charging. Therefore, using at least one of hard carbon, artificial graphite, natural graphite, silicon-based materials, tin-based materials, and lithium titanate as the negative electrode active material facilitates a rapid ion diffusion path, improves electrochemical kinetics performance, and enhances cycle stability and initial coulombic efficiency.

[0051] When the battery is a sodium-ion battery, the negative electrode active material can be hard carbon.

[0052] Furthermore, silicon-based materials include at least one of elemental silicon, silicon oxide, silicon alloys, and composite silicon; and / or tin-based materials include at least one of tin oxide and tin alloys. Elemental silicon has a high theoretical capacity, which is beneficial for improving the energy density of batteries. Simultaneously, elemental silicon is widely available, which helps reduce the cost of negative electrode active materials. Silicon oxide combines the characteristics of silicon and silicon oxide, maintaining a high theoretical capacity while reducing volume expansion and improving the cycle stability of the battery. Silicon alloys refer to alloys formed by silicon with other metals or elements. These alloys can improve cycle stability and mechanical properties while maintaining high capacity. Composite silicon has good stability and long cycle life. During charging, lithium ions intercalate and react with the oxide to generate metallic tin and lithium oxide; during discharging, this process reverses, releasing lithium ions and restoring the original oxide state. Tin alloys include alloys formed by tin (Sn) with lithium (Li) or sodium (Na). During charging, lithium or sodium ions react with Sn to form metallic alloys LixSn or NaxSn, where x represents the number of intercalated lithium or sodium atoms. During discharge, this process proceeds in reverse, with the alloy decomposing and releasing lithium or sodium ions back into the electrolyte. Therefore, using at least one of elemental silicon, silicon oxide, silicon alloy, composite silicon, tin oxide, and tin alloy as the negative electrode active material in silicon-based materials is beneficial for improving the cycle stability of the battery.

[0053] According to some embodiments of this disclosure, the negative electrode also includes a conductive agent. The conductive agent can build a more complete conductive structure in the negative electrode, forming more conductive channels and improving the short-range and long-range conductivity of the negative electrode. Therefore, the negative electrode has good conductivity, meaning that the conductive agent in the negative electrode can form a more complete conductive structure with the negative electrode active material, thereby improving the short-range and long-range conductivity of the negative electrode.

[0054] The conductive agent content in the negative electrode is 0.1wt% to 10wt%. This content is reasonable, allowing the conductive agent to fully function, improving the conductivity of the negative electrode while avoiding waste and reducing its cost, thus enhancing its market competitiveness.

[0055] Furthermore, the conductive agent includes at least one of conductive carbon black, carbon nanotubes, graphene, conductive graphite, and carbon fiber. Conductive carbon black, through its high specific surface area, network structure, and conductive pathways between particles, can impart excellent conductivity to the positive electrode conductive agent at low addition levels. Carbon nanotubes have very high conductivity, which is beneficial for reducing the internal resistance of the battery and improving its high-rate performance and cycle performance. Carbon nanotubes have low specific gravity and high strength, providing strong mechanical support and a conductive network. Graphene has good conductivity and extremely low resistance and high carrier mobility. Conductive graphite has a unique crystal structure and electronic properties, resulting in good conductivity. Carbon fiber is composed of tiny fibers made of carbon atoms arranged in a hexagonal lattice similar to graphite. When these fibers are stretched into long fibers, the carbon atoms tend to align along the fiber axis, resulting in high conductivity in the fiber axis direction. Therefore, using at least one of conductive carbon black, carbon nanotubes, graphene, conductive graphite, and carbon fiber in conductive agents can improve the conductivity of the conductive agents and reduce their cost.

[0056] According to some embodiments of this disclosure, the negative electrode sheet further includes a binder, which can be a conventional bonding material in the art. For example, the binder includes one or more of carboxymethyl cellulose (CMC), styrene-butadiene rubber (SBR), polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide-containing polymers, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamide-imide, polyvinyl alcohol, and sodium polyacrylate. The mass fraction of the binder in the negative electrode sheet can be from 0.5% to 15%, for example, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 8%, 10%, 13%, 15%, or any combination thereof.

[0057] The method for preparing a negative electrode sheet according to some embodiments of this disclosure includes the following steps: mixing a negative electrode active material, a conductive agent, a binder and a solvent to form a slurry, and coating the slurry onto a current collector to obtain a negative electrode sheet.

[0058] According to the method for preparing the negative electrode sheet according to the embodiments of this disclosure, the above preparation method is relatively simple and improves the preparation efficiency of the negative electrode sheet.

[0059] According to some embodiments of this disclosure, the slurry is coated using a dry process, a wet process, a double-layer coating, laser scribing, or magnetic induction.

[0060] According to some embodiments of this disclosure, the solvent can be deionized water, N-methylpyrrolidone, or other conventional solvents in the art, which will not be elaborated here.

[0061] The electrical device according to a second aspect of the present disclosure includes at least one battery according to the first aspect of the present disclosure described above.

[0062] According to the embodiments of this disclosure, the electrical equipment operates stably, which can improve the user experience and thus enhance the market competitiveness of the electrical equipment.

[0063] Specifically, the aforementioned electrical equipment can include, but is not limited to, electric vehicles, electric cars, mobile phones, tablets, laptops, electric toys, ships, and spacecraft. Among them, electric toys can include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, while spacecraft can include airplanes, rockets, and space shuttles.

[0064] The embodiments of this disclosure are described in detail below. It should be noted that the embodiments described below are exemplary and are only used to explain this disclosure, and should not be construed as limiting this disclosure. In addition, unless otherwise specified, all reagents used in the following embodiments are commercially available or can be synthesized according to the methods described herein or known to others. For reaction conditions not listed, they are also readily available to those skilled in the art.

[0065] Example 1:

[0066] The positive electrode active material lithium iron phosphate (LiFePO4), conductive agent (conductive carbon black SP), and binder PVDF (polyvinylidene fluoride) are mixed in a ratio of 97:1:2. The powder and NMP (N-methyl-2-pyrrolidone) are stirred into a positive electrode slurry using a homogenizer and then uniformly coated onto aluminum foil to form a positive electrode sheet.

[0067] The negative electrode active material graphite, high-performance conductive carbon black, thickener CMC (carboxymethyl cellulose), and binder SBR (styrene-butadiene rubber) are mixed in a ratio of 96:1:1:2. The powder and deionized water are then stirred using a homogenizer to form a negative electrode slurry, which is then uniformly coated onto copper foil to produce a negative electrode sheet. The negative electrode sheet satisfies the following condition: k*D3*D2*η 2 / [γ*D0*D1]=11.02.

[0068] Ethylene carbonate (EC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC) were mixed in a volume ratio of 1:1:1 to prepare an electrolyte containing 1M LiPF6.

[0069] Polypropylene separators were used to prepare stacked batteries, and their fast-charging capacity retention rate was tested.

[0070] Example 2:

[0071] The positive electrode active material lithium iron phosphate (LiFePO4), conductive agent (conductive carbon black SP), and binder PVDF are mixed in a ratio of 97:1:2. The powder and NMP are stirred into a positive electrode slurry using a homogenizer and then uniformly coated onto aluminum foil.

[0072] The negative electrode active material graphite, high-performance conductive carbon black, thickener (CMC), and binder (SBR) are mixed in a ratio of 96:1:1:2. The powder and deionized water are then stirred using a homogenizer to form a negative electrode slurry, which is then uniformly coated onto copper foil. The negative electrode sheet satisfies k*D3*D2*η. 2 / [γ*D0*D1]=9.46.

[0073] Ethylene carbonate (EC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC) were mixed in a volume ratio of 1:1:1 to prepare an electrolyte containing 1 M LiPF6.

[0074] Polypropylene separators were used to prepare stacked batteries, and their fast-charging capacity retention rate was tested.

[0075] Example 3:

[0076] The positive electrode active material lithium iron phosphate (LiFePO4), conductive agent (conductive carbon black SP), and binder PVDF are mixed in a ratio of 97:1:2. The powder and NMP are stirred into a positive electrode slurry using a homogenizer and then uniformly coated onto aluminum foil.

[0077] The negative electrode active material graphite, high-performance conductive carbon black, thickener (CMC), and binder (SBR) are mixed in a ratio of 96:1:1:2. The powder and deionized water are then stirred using a homogenizer to form a negative electrode slurry, which is then uniformly coated onto copper foil. The negative electrode sheet satisfies k*D3*D2*η. 2 / [γ*D0*D1]=9.36.

[0078] Ethylene carbonate (EC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC) were mixed in a volume ratio of 1:1:1 to prepare an electrolyte containing 1 M LiPF6.

[0079] Polypropylene separators were used to prepare stacked batteries, and their fast-charging capacity retention rate was tested.

[0080] Example 4:

[0081] Example 4 is basically the same as Example 2, except that the negative electrode sheet satisfies: k*D3*D2*η2 / [γ*D0*D1]=9.

[0082] Example 5:

[0083] Example 5 is basically the same as Example 2, except that the negative electrode sheet satisfies: k*D3*D2*η 2 / [γ*D0*D1]=15.

[0084] Example 6:

[0085] Example 6 is basically the same as Example 2, except that the negative electrode sheet satisfies k*D3*D2*η. 2 / [γ*D0*D1]=6.43.

[0086] Example 7:

[0087] Example 7 is basically the same as Example 2, except that the negative electrode sheet satisfies k*D3*D2*η. 2 / [γ*D0*D1]=5.68.

[0088] Comparative Example 1:

[0089] The positive electrode active material lithium iron phosphate (LiFePO4), conductive agent (conductive carbon black SP), and binder PVDF are mixed in a ratio of 97:1:2. The powder and NMP are stirred into a positive electrode slurry using a homogenizer and then uniformly coated onto aluminum foil.

[0090] The negative electrode active material graphite, high-performance conductive carbon black, thickener (CMC), and binder (SBR) are mixed in a ratio of 96:1:1:2. The powder and deionized water are then stirred using a homogenizer to form a negative electrode slurry, which is then uniformly coated onto copper foil. The negative electrode sheet satisfies k*D3*D2*η. 2 / [γ*D0*D1]=3.31.

[0091] Ethylene carbonate (EC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC) were mixed in a volume ratio of 1:1:1 to prepare an electrolyte containing 1 M LiPF6.

[0092] Polypropylene separators were used to prepare stacked batteries, and their fast-charging capacity retention rate was tested.

[0093] Comparative Example 2:

[0094] Comparative Example 2 is basically the same as Comparative Example 1, except that the negative electrode sheet satisfies k*D3*D2*η. 2 / [γ*D0*D1]=16.34.

[0095] Table 1. Parameters of Examples 1-7 and Comparative Examples 1-2

[0096] Battery performance test

[0097] DC internal resistance (DCIR) test, the test method is as follows:

[0098] A. 25℃, 0.2C charge / discharge, calibrate battery capacity;

[0099] B. Charge at 0.2C to 50% SOC (State of Charge);

[0100] C. Set up 2C and 4C charging respectively, record the termination voltage and termination current for each process, and calculate DCIR (Direct Current Internal Resistance). DCIR = (V1 - V2) / I, and the results are summarized in Table 1. V1 is the voltage after 30 seconds of charging, V2 is the voltage after the battery is adjusted to the target SOC and left to stand for 30 minutes, and I is the charging current.

[0101] Table 2 Battery performance data for Examples 1-7 and Comparative Examples 1-2

[0102] DC internal resistance is one of the important indicators for evaluating battery performance. Lower internal resistance means that the battery can transfer current more efficiently under high current operation, reducing heat generation and thus improving battery efficiency and lifespan. Compared with Comparative Examples 1-2, the DC internal resistance values ​​of Examples 1-7 are all reduced, meaning that the batteries corresponding to Examples 1-7 have lower resistance. This means that under the same current conditions, the voltage drop generated by the battery is smaller, so the battery can transfer current more efficiently, which helps to reduce internal energy loss, improve fast charging efficiency, and extend battery life.

[0103] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this disclosure. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example.

[0104] Although embodiments of this disclosure have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of this disclosure, the scope of which is defined by the claims and their equivalents.

Claims

1. A battery, characterized in that, The battery includes a negative electrode plate, and the negative electrode plate includes a negative electrode active material. The negative electrode plate satisfies: 5 ≤ k * D3 * D2 * η 2 / [γ*D0*D1]≤15; where η is the OI value of the negative electrode, D0 is the most frequent pore size of the negative electrode in nm, D1 is the Dv50 of the negative electrode active material in μm, D2 is the most probable pore size of the negative electrode in nm, D3 is the average pore diameter of the negative electrode in nm, γ is the N / P ratio of the battery, and k=1000.

2. The battery according to claim 1, characterized in that, The negative electrode plate satisfies: 9 ≤ k * D3 * D2 * η 2 / [γ*D0*D1]≤15.

3. The battery according to claim 1 or 2, characterized in that, The D0 satisfies: 10nm ≤ D0 ≤ 150nm; and / or The γ satisfies: 1.01 ≤ γ ≤ 1.5; and / or The D1 satisfies: 5μm≤D1≤20μm; and / or The D2 satisfies: 0.5nm ≤ D2 ≤ 5nm; and / or The D3 satisfies: 15nm ≤ D3 ≤ 30nm; and / or The condition η satisfies: 2≤η≤20.

4. The battery according to any one of claims 1-3, characterized in that, The D0 satisfies: 20nm ≤ D0 ≤ 35nm; and / or The γ satisfies: 1.01 ≤ γ ≤ 1.2; and / or The D1 satisfies: 10μm≤D1≤15μm; and / or The D2 satisfies: 1.5nm ≤ D2 ≤ 2nm; and / or The D3 satisfies: 20nm ≤ D3 ≤ 25nm; and / or The condition η satisfies: 8≤η≤15.

5. The battery according to any one of claims 1-4, characterized in that, The content of the negative electrode active material in the negative electrode sheet is 80wt% to 98wt%.

6. The battery according to any one of claims 1-5, characterized in that, The negative electrode active material includes at least one of hard carbon, artificial graphite, natural graphite, silicon-based materials, tin-based materials, and lithium titanate.

7. The battery according to claim 6, characterized in that, The silicon-based material includes at least one of elemental silicon, silicon oxide, silicon alloy, and composite silicon; and / or The tin-based material includes at least one of tin oxide and tin alloy.

8. The battery of any one of claims 1-7, wherein, The negative electrode also includes a conductive agent, and the content of the conductive agent in the negative electrode is 0.1wt% to 10wt%.

9. The battery of claim 8, wherein, The conductive agent includes at least one of conductive carbon black, carbon nanotubes, graphene, conductive graphite, and carbon fiber.

10. An electric device, characterized by It includes at least one battery according to any one of claims 1-9.

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