Positive plate, battery comprising positive plate and electric device

Abstract

The invention relates to a positive plate, a battery comprising the positive plate and an electric device, and belongs to the technical field of batteries. According to the invention, the element M is doped in and / or coated on the surface of the nickel cobalt lithium manganate particles, the bond energy of the element M and O is controlled to be greater than the bond energy of Ni and O, and the ratio of the Fd3m phase thickness in the nickel cobalt lithium manganate particles and the ratio of the mass ratio of M to the relative mass ratio of Ni in the positive electrode material meet a specific relationship, so that the structural stability of the nickel cobalt lithium manganate is remarkably improved; the lithium ion transmission efficiency is higher, the fast charging performance is better, and the higher capacity performance can be realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of batteries, in particular to a positive electrode sheet, a battery comprising the positive electrode sheet and a power utilization device. BACKGROUND

[0002] Ternary materials have high specific capacity, excellent cycle stability, good rate performance and other advantages, and are widely used. However, during the charge and discharge cycle process, the crystal structure of the ternary material will irreversibly degrade, causing oxygen to be released, and then triggering a series of side reactions, ultimately forming a high impedance layer on the surface of the positive electrode particles and the interface with the electrolyte, causing the battery internal resistance to increase significantly, and deteriorating the fast charging performance of the battery. SUMMARY

[0003] The present application aims to overcome the shortcomings of the prior art and provide a positive electrode sheet, a battery comprising the positive electrode sheet and a power utilization device, so that the positive electrode sheet using ternary materials has good lithium ion transmission performance, good fast charging performance and capacity.

[0004] To achieve the above-mentioned purpose, in a first aspect, the present application provides a positive electrode sheet, comprising a positive electrode current collector and a positive electrode material layer arranged on at least one side of the positive electrode current collector, the positive electrode material layer comprising a positive electrode material, the positive electrode material comprising a positive electrode active material, the positive electrode active material comprising lithium nickel cobalt manganese oxide (NCM) particles, the lithium nickel cobalt manganese oxide particles comprising an Fd3m phase, the lithium nickel cobalt manganese oxide particles further comprising an element M, the bond energy between the element M and O being greater than the bond energy between Ni and O. The positive electrode sheet satisfies 0.25≤a / b≤2700. Wherein a% is the percentage of the thickness of the Fd3m phase to the diameter of the lithium nickel cobalt manganese oxide particles after the positive electrode sheet is cycled for 200 cycles. b=b1 / b2, b1 is the mass percentage of the element M in the positive electrode material, and b2 is the mass percentage of the element Ni in the positive electrode material based on the total mass of the elements Ni, Co and Mn.

[0005] In a second aspect, the present application provides a battery comprising the positive electrode sheet.

[0006] In a third aspect, the present application provides a power utilization device comprising the battery.

[0007] Compared with the prior art, the beneficial effects of this application include: by doping and / or coating the surface of NCM particles with element M, and controlling the bond energy between element M and O to be greater than that between Ni and O, and after the cathode sheet is cycled for 200 times, the percentage of Fd3m phase thickness to the diameter of lithium nickel cobalt manganese oxide particles (a%) and the ratio of the mass percentage of M to the relative mass percentage of Ni in the cathode material (b) satisfy a specific relationship, not only is the structural stability of lithium nickel cobalt manganese oxide significantly improved, the lithium-ion transport efficiency is higher, the fast charging performance is better, and the capacity performance is also achieved. Attached Figure Description

[0008] Figure 1 This is a transmission electron microscope (TEM) image of the cathode material powder in Example 32. Detailed Implementation

[0009] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0010] In this application, the technical features described in an open-ended manner include both closed technical solutions consisting of the listed features and open technical solutions that include the listed features.

[0011] In this application, numerical ranges are referred to as continuous unless otherwise specified, and include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0012] In this application, there are no particular restrictions on the specific dispersion and mixing methods.

[0013] Unless otherwise specified, all reagents or instruments used in this application are commercially available products.

[0014] "Positive electrode material" refers to the material of the positive electrode material layer, which includes positive electrode active material, conductive agent and binder, etc.

[0015] Positive electrode film According to a first aspect of this application, a positive electrode sheet is provided, comprising a positive current collector and a positive electrode material layer disposed on at least one side of the positive current collector, the positive electrode material layer comprising a positive electrode material, the positive electrode material comprising a positive electrode active material, the positive electrode active material comprising lithium nickel cobalt manganese oxide particles, the lithium nickel cobalt manganese oxide particles comprising an Fd3m phase, the lithium nickel cobalt manganese oxide particles further comprising element M, wherein the bond energy between element M and O is greater than the bond energy between Ni and O; The positive electrode plate satisfies: 0.25≤a / b≤2700; Wherein, a% is the percentage of the Fd3m phase thickness to the diameter of the lithium nickel cobalt manganese oxide particles after the positive electrode plate has been cycled 200 times; b = b1 / b2, where b1 is the mass percentage of element M in the cathode material (denoted as "M mass percentage", which is calculated based on the mass of the cathode material), and b2 is the mass percentage of element Ni in the cathode material based on the total mass of elements Ni, Co and Mn (denoted as "Ni relative mass percentage").

[0016] During charging, lithium ions are released from the lithium nickel cobalt manganese oxide cathode material, and transition metal ions (mainly nickel ions) are oxidized to higher valence states (such as Ni). 3+ → Ni 4+ ), and has a strong oxidizing property for oxygen, which in turn leads to the formation of oxygen ions (O) in the crystal lattice. 2- The loss of electrons, the oxidation to oxygen (O2) or the escape of oxygen free radicals from the crystal lattice, can be represented as: 2 O 2- (Crystal lattice) → O2 (gas) + 4e - .

[0017] The release of oxygen disrupts the metal-oxygen chemical bonds, causing the originally stable layered structure (α-NaFeO2 type structure) to partially collapse. This results in the transformation of the lithium nickel cobalt manganese oxide material surface from a layered structure that is a good lithium-ion conductor to a more stable Fd3m phase structure that isolates lithium ions. Typically, phase transformations begin at the particle edges, and the resulting Fd3m phase structure is continuous. Transition metals, especially Ni, in the Fd3m phase occupy lithium sites, causing ion channel blockage, making delithiation difficult, and degrading fast-charging performance.

[0018] The aforementioned cathode material incorporates element M in its lithium nickel cobalt manganese oxide particles. The bond energy between metal element M and O is greater than that between Ni and O. These strong MO bonds act as reinforcing points in the crystal structure, making it more difficult for oxygen atoms to be oxidized and precipitated, thus improving the structural stability of the material. Furthermore, element M typically occupies transition metal sites and is not easily migrated. When strong bonded element M is present, cation migration requires twisting or bypassing these strong MO bonds, which significantly increases the risk of Ni oxidation. 2+The energy barrier of migration helps reduce the risk of Ni occupying lithium sites and reduce lattice distortion during the delithiation process, thereby improving the smoothness of the delithiation process and optimizing the lithium-ion transport performance. At the same time, by adjusting the percentage of Fd3m phase thickness to the diameter of lithium nickel cobalt manganese oxide particles (a%) and the ratio of M mass percentage to Ni relative mass percentage (b) after 200 cycles of the positive electrode sheet to satisfy the above specific relationship, not only is the structural stability of lithium nickel cobalt manganese oxide significantly improved, the lithium-ion transport efficiency is higher, the fast charging performance is better, but also the capacity performance is higher.

[0019] If the value of a / b is too large, the structural stability of the lithium nickel cobalt manganese oxide particles is insufficient, making delithiation difficult, resulting in low lithium-ion transport efficiency and poor fast charging performance. If the value of a / b is too small, the content of element Ni is low, leading to low capacity. Therefore, it is necessary to control the value of a / b within the above range to achieve a balance between fast charging performance and capacity.

[0020] a% = after the positive electrode plate has been circulated for 200 cycles, the average thickness of the Fd3m phase / the average diameter of the lithium nickel cobalt manganese oxide particles × 100%, where the average thickness of the Fd3m phase and the average diameter of the lithium nickel cobalt manganese oxide particles are both in μm.

[0021] This application does not limit the method for detecting the average thickness of the Fd3m phase and the average diameter of the lithium nickel cobalt manganese oxide particles after 200 cycles of the positive electrode sheet. Those skilled in the art can perform the detection using conventional techniques. For example, they can be detected using the following methods: 1) Cyclic treatment: Discharge the battery at 0.33C to the lower limit voltage of 2.5V, then charge the battery at a constant current rate of 1C to 4.25V, then charge at a constant voltage to the cutoff current of 0.05C, and then discharge at a constant current rate of 1C to the voltage of 2.5V; this is one charge-discharge cycle, and the charge-discharge cycle is 200 cycles; 2) Pretreatment: Discharge the cycled battery to the lower limit voltage of 2.5V at 0.33C. Take the positive electrode sheet in the empty state and soak it in dimethyl carbonate (DMC) solution at 25°C for 4 hours. Then take out the electrode sheet and dry it in a vacuum environment. Use a ceramic knife to scrape off the positive electrode material powder on the surface of the electrode sheet. 3) The average diameter and average thickness of the Fd3m phase in the lithium nickel cobalt manganese oxide particles in the cathode material powder were measured. The specific measurement method is as follows: Random blind scanning high-magnification (100kx-200kx, i.e., 100,000x-200,000x) transmission electron microscopy was performed on the particle edges to obtain lattice fringe images. The lattice fringe spacing at the edges was measured using MEARSURE NANO software. The distribution area with a lattice fringe spacing of 0.207±0.01nm (the lattice spacing of Fd3m in Ni-O) can be identified as the Fd3m phase. The thickness of the Fd3m phase was measured at 10 locations on the same particle to obtain the average thickness of the Fd3m phase. In addition, a lattice fringe spacing of 0.473±0.01nm indicates a layered phase. The lattice fringe spacing can be used to distinguish between the Fd3m phase and the layered phase. Furthermore, the magnification of the transmission electron microscope was adjusted to 2kx (i.e., 2,000x), and the measurement was performed using MEARSURE NANO software. The NANO software was used to collect the diameter of lithium nickel cobalt manganese oxide particles using the cross-hatching method. Five particles were counted, and the average value was calculated to obtain the average diameter of the lithium nickel cobalt manganese oxide particles.

[0022] After 200 cycles of the positive electrode, the average thickness of the Fd3m phase can be adjusted by adjusting at least one of the following process parameters: sintering temperature and time (such as the temperature and / or time of the second holding section in sintering), oxygen content in the sintering atmosphere, water content in the electrolyte, replacing LiPF6 with lithium salts such as LiFSi and adjusting its content, adding film-forming additives and adjusting their content.

[0023] After the positive electrode plate is circulated for 200 cycles, the average diameter of the lithium nickel cobalt manganese oxide particles can be adjusted by adjusting at least one of the following process parameters: pH value of the reaction solution, concentration of complexing agent and stirring speed when preparing lithium nickel cobalt manganese oxide precursor.

[0024] This application does not limit the detection method for the mass percentage of M b1 and the relative mass percentage of Ni b2; those skilled in the art can perform the detection using conventional techniques. For example, the mass percentage of M b1 and the relative mass percentage of Ni b2 can be detected using the following methods: Discharge the battery at 0.33C to the lower limit voltage of 2.5V to obtain an empty battery. Disassemble the empty battery to obtain the positive electrode. Soak the positive electrode in DMC (dimethyl carbonate) at room temperature (25℃, the same below) for 60 minutes, take it out, and dry it at room temperature with humidity ≤15%. The positive electrode material layer on the surface of the positive electrode current collector is scraped off to obtain positive electrode material powder; Accurately weigh 0.5 ± 0.0005 g of positive electrode material powder and place it in a dry, clean, and impurity-free quartz crucible. Add 5 mL of hydrochloric acid and digest at 190 °C for 15 min. Add 10 mL of ultrapure water along the wall of the crucible and digest for another 15 min. Add 1 mL of nitric acid and digest for 2 min. Remove the crucible and cool to room temperature. Transfer the solution to a 50 mL centrifuge tube and dilute to the mark with ultrapure water. Mix well to obtain the test solution. The hydrochloric acid used contains 37% HCl by mass, and the nitric acid contains 68% HNO3 by mass. ICP (Inductively Coupled Plasma) testing is performed on the solution to be tested. Based on the characteristics of the sample and the elements to be detected, appropriate ICP instrument operating conditions are set, such as: gas flow rate 0.5 L / min, power 1150 W, and the element detection wavelength is selected (depending on the element being tested, e.g., Ni wavelength 231.60 nm, Mg wavelength 279.08 nm, Al wavelength 396.15 nm, Ti wavelength 323.452 nm, Zr wavelength 336.12 nm, Nb wavelength 309.4 nm, W wavelength 239.7 nm, Y wavelength 371 nm, Co wavelength 238.892 nm, Mn wavelength 257.61 nm). The content of each element is read using the self-analysis function of the ICP testing software, and then the mass percentage of M (b1) and the relative mass percentage of Ni (b2) are calculated.

[0025] Before performing ICP testing on the test solution, a standard solution needs to be prepared. Usually, a 1000 mg / L standard solution (a solution containing the element to be tested, which is commercially available) is diluted with deionized water to different concentrations (generally 0, 1 mg / 100mL, 2 mg / 100mL and 3 mg / 100mL) to ensure that the linear correlation coefficient of the standard concentration is ≥0.999.

[0026] The value of b can be adjusted by adjusting at least one of the following process parameters: Ni content in lithium nickel cobalt manganese oxide, dopant content (if any), and coating layer ratio (if any).

[0027] For example, a / b is an interval range formed by any two values ​​of 0.25, 0.5, 1, 5, 10, 30, 50, 70, 100, 300, 500, 700, 1000, 1200, 1500, 1800, 2000, 2200, 2500, 2700 or more.

[0028] In some embodiments, the positive electrode plate satisfies: 2 ≤ a / b ≤ 530. In one embodiment, the positive electrode plate satisfies: 2 ≤ a / b ≤ 98.

[0029] By controlling the value of a / b within the range of 2 to 530 (e.g., within the range formed by any two values ​​of 2, 5, 10, 30, 50, 70, 100, 150, 200, 250, 300, 350, 400, 450, 500 or above), especially within the range of 2 to 98 (e.g., within the range formed by any two values ​​of 2, 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, 98 or above), the structure of the lithium nickel cobalt manganese oxide particles is made more stable, the lithium-ion transmission performance is better, and the fast charging performance is superior, while maintaining a high capacity.

[0030] In some implementations, the range of a% is 0.01% to 4%. For example, a% is an interval formed by any two values ​​of 0.01%, 0.03%, 0.05%, 0.07%, 1%, 1.2%, 1.5%, 1.7%, 2.0%, 2.2%, 2.5%, 2.8%, 3%, 3.2%, 3.5%, 3.8%, 4%, or more.

[0031] In one embodiment, the range of a% is 0.04% to 2%.

[0032] Controlling the percentage of a% within the range of 0.01% to 4%, especially within the range of 0.04% to 2%, can improve the lithium-ion transport performance and fast-charging performance of lithium nickel cobalt manganese oxide particles. On the other hand, it can enhance the surface stability of lithium nickel cobalt manganese oxide particles, reduce the erosion of the cathode material surface by the electrolyte, weaken the risk of oxidative decomposition of the catalytic electrolyte, and avoid the generation of acidic substances such as HF that could damage the cathode material structure, thereby increasing the battery capacity.

[0033] In some embodiments, the value of b ranges from 0.001 to 0.06. In one embodiment, the value of b ranges from 0.003 to 0.03. Controlling the value of b within the range of 0.001 to 0.06, particularly within the range of 0.003 to 0.03, allows for a more suitable ratio of element Ni to element M in the cathode material. This not only utilizes Ni to increase capacity but also better utilizes element M to improve the stability of lithium nickel cobalt manganese oxide particles, reduces the number of lithium sites occupied by Ni on the particle surface, improves lithium-ion transport, and enhances fast-charging performance. This, in turn, helps to balance the capacity and fast-charging performance of batteries using the cathode sheet. For example, b can be any two values ​​within the range of 0.001, 0.003, 0.005, 0.007, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, or more.

[0034] In some embodiments, b2 ranges from 50% to 98%, resulting in higher capacity. For example, b2 is a range formed by any two values ​​of 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 98%, or higher. In one embodiment, b2 ranges from 60% to 95%, which not only results in higher capacity but also better structural stability of lithium nickel cobalt manganese oxide, superior lithium-ion transport performance, and greater advantages for fast charging.

[0035] In some embodiments, the range of b1 is 0.05% to 4%. For example, b1 is an interval formed by any two values ​​of 0.05%, 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, or higher. In one embodiment, the range of b1 is 0.1% to 2%.

[0036] When b1 is in the range of 0.05% to 4%, especially in the range of 0.1% to 2%, it can better improve the structural stability of lithium nickel cobalt manganese oxide particles, enhance the smoothness of the delithiation process, optimize the lithium ion transport performance, and ensure that the cathode material has a higher capacity.

[0037] In some embodiments, when the mass percentage of Ni, Co, and Mn in the lithium nickel cobalt manganese oxide particles is ≥70% based on the total mass of Ni, Co, and Mn elements, the range of b1 is 0.1%~4%, such as 0.1%, 0.2%, 0.5%, 0.8%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, or any two of the above values. When the mass percentage of Ni in the lithium nickel cobalt manganese oxide particles is ≥70% based on the total mass of Ni, Co, and Mn elements, the increased nickel content leads to increased oxygen release from the crystal lattice. Controlling b1 within the range of 0.1%~4% can better improve the structural stability of the lithium nickel cobalt manganese oxide particles, increase lithium-ion transport efficiency, and enhance fast-charging performance.

[0038] In some embodiments, after 200 cycles of the positive electrode, the average thickness of the Fd3m phase ranges from 0.8 to 20 nm. For example, after 200 cycles of the positive electrode, the average thickness of the Fd3m phase is within the range of any two of the following values: 0.8 nm, 1 nm, 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, 11 nm, 12 nm, 13 nm, 14 nm, 15 nm, 16 nm, 17 nm, 18 nm, 19 nm, 20 nm. In one embodiment, after 200 cycles of the positive electrode, the average thickness of the Fd3m phase ranges from 4 to 8 nm.

[0039] When the average thickness of the Fd3m phase is in the range of 0.8~20nm, especially in the range of 4~8nm, it can, on the one hand, weaken the obstruction of lithium-ion transport by the inert Fd3m phase and improve fast charging performance. On the other hand, it can improve surface stability, weaken the erosion of the cathode material surface by the electrolyte, reduce the catalytic oxidation decomposition of the electrolyte on the cathode surface and the generation of acidic substances such as HF, thereby avoiding damage to the cathode material structure by acidic substances and ensuring the capacity stability of the battery.

[0040] In some embodiments, the average diameter of the lithium nickel cobalt manganese oxide particles ranges from 1.3 to 20 μm. When the average diameter of the lithium nickel cobalt manganese oxide particles is within this range, it provides a more suitable lithium-ion transport path, which is beneficial for improving the fast-charging performance of the battery.

[0041] For example, the average diameter of the lithium nickel cobalt manganese oxide particles is within the range formed by any two of the following values: 1.3 μm, 1.5 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 18 μm, 20 μm.

[0042] In some embodiments, after 200 cycles of the positive electrode, the difference between the maximum thickness of the Fd3m phase and its minimum thickness is ≤16 nm, such that the difference is within the range formed by any two of the following values: 16 nm, 15 nm, 14 nm, 13 nm, 12 nm, 11 nm, 10 nm, 8 nm, 6 nm, 4 nm, 2 nm, 1 nm, 0.5 nm, or more. In one embodiment, after 200 cycles of the positive electrode, the difference between the maximum thickness of the Fd3m phase and its minimum thickness is ≤15 nm.

[0043] After the positive electrode is circulated for 200 cycles, the difference between the maximum thickness of the Fd3m phase and its minimum thickness is ≤16nm, especially ≤15nm. This can reduce the difference in the delithiation rate of lithium nickel cobalt manganese oxide particles in different regions, improve the consistency of lithium ion transport rate in different regions, and make the fast charging performance better.

[0044] This application does not limit the method for detecting the difference between the maximum thickness of the Fd3m phase and its minimum thickness after 200 cycles of the positive electrode sheet. Those skilled in the art can perform the detection using conventional techniques. For example, the difference between the maximum thickness of the Fd3m phase and its minimum thickness can be detected using the following method: 1) Cyclic treatment: Discharge the battery at 0.33C to the lower limit voltage of 2.5V, then charge the battery at a constant current rate of 1C to 4.25V, then charge at a constant voltage to the cutoff current of 0.05C, and then discharge at a constant current rate of 1C to the voltage of 2.5V; this is one charge-discharge cycle, and the charge-discharge cycle is 200 cycles; 2) Pretreatment: Discharge the cycled battery to the lower limit voltage of 2.5V at 0.33C. Take the positive electrode sheet of the battery in the empty state and soak it in dimethyl carbonate (DMC) solution at 25°C for 4 hours. Then take out the electrode sheet and dry it in a vacuum environment. Use a ceramic knife to scrape off the positive electrode material powder on the surface of the electrode sheet. 3) The average diameter and average thickness of the Fd3m phase of lithium nickel cobalt manganese oxide particles in the cathode material powder were measured. The specific measurement method is as follows: Random blind scanning high-magnification (100kx-200kx, i.e., 100,000x-200,000x) transmission imaging was performed on the edge of the particles to obtain lattice fringe images at the particle edge. The spacing of the lattice fringe at the edge was measured using MEARSURE NANO software. The distribution area with a lattice fringe spacing of 0.207±0.01nm (the lattice spacing of Fd3m in Ni-O) can be identified as the Fd3m phase. The thickness of the Fd3m phase was measured at 10 locations of the same particle. Based on the thickness of the Fd3m phase at 10 locations, the maximum thickness and minimum thickness were obtained. Five particles were counted to obtain the maximum thickness and minimum thickness respectively. The average value of the maximum thickness and the average value of the minimum thickness of the five particles were calculated. Then, the difference between the two average values ​​was calculated to obtain the difference between the maximum thickness and the minimum thickness of the Fd3m phase.

[0045] In some embodiments, the element M is selected from at least one of Zr, Ti, Si, Mo, B, Nb, Sb, Ta, Al, W, Sr, V, Y, Mg, and Ca.

[0046] In some embodiments, the surface of the lithium nickel cobalt manganese oxide particles is provided with a coating layer containing element M.

[0047] In some embodiments, a coating layer is formed on the surface of the lithium nickel cobalt manganese oxide particles. The coating layer material includes at least one selected from tungsten oxide, boron oxide, and aluminum oxide. Forming a coating layer containing the aforementioned specific materials on the surface of the lithium nickel cobalt manganese oxide particles can also protect the interface and improve cycle performance.

[0048] In some embodiments, the lithium nickel cobalt manganese oxide particles contain element M in a region from a depth of 1 / 3R to a depth of 2 / 3R from the surface, where R is the diameter of the lithium nickel cobalt manganese oxide particles.

[0049] The element M can be contained in the lithium nickel cobalt manganese oxide particles in the form of coating, doping, or both. Cobalt ions (Co...)3+ Co has a small radius (0.0545 nm) and is usually present in the +3 valence state in materials, making it very stable. 3+ Its presence can "pin" it into the transition metal layer, inhibiting the migration of nickel ions to the lithium layer, which is beneficial to maintaining the regular layered structure of the material.

[0050] In some embodiments, the total molar amount of elements Ni, Co, and Mn in the cathode material is used as a basis, and the molar percentage of Co ranges from 2% to 30%. For example, a molar percentage within the range formed by any two values ​​of 2%, 4%, 6%, 8%, 10%, 12%, 14%, 16%, 18%, 20%, 22%, 24%, 26%, 28%, 30%, or higher, can better utilize Co. 3+ It inhibits the migration of nickel ions to the lithium layer, thus better maintaining the material's regular layered structure and improving fast charging performance.

[0051] This application does not limit the method for detecting the molar percentage of Co in the cathode material based on the total molar amounts of Ni, Co, and Mn. Those skilled in the art can perform the detection using conventional techniques. For example, the molar percentage of Co in the cathode material based on the total molar amounts of Ni, Co, and Mn can be detected using the following method: Discharge the battery at 0.33C to the lower limit voltage of 2.5V to obtain an empty battery. Disassemble the empty battery to obtain the positive electrode. Soak the positive electrode in DMC (dimethyl carbonate) at room temperature (25℃, the same below) for 60 minutes, take it out, and dry it at room temperature with humidity ≤15%. The positive electrode material layer on the surface of the positive electrode current collector is scraped off to obtain positive electrode material powder; Accurately weigh 0.5 ± 0.0005 g of positive electrode material powder and place it in a dry, clean, and impurity-free quartz crucible. Add 5 mL of hydrochloric acid and digest at 190 °C for 15 min. Add 10 mL of ultrapure water along the wall of the crucible and digest for another 15 min. Add 1 mL of nitric acid and digest for 2 min. Remove the crucible and cool to room temperature. Transfer the solution to a 50 mL centrifuge tube and dilute to the mark with ultrapure water. Mix well to obtain the test solution. The hydrochloric acid used contains 37% HCl by mass, and the nitric acid contains 68% HNO3 by mass. ICP (Inductively Coupled Plasma) testing is performed on the solution to be tested. Based on the characteristics of the sample and the elements to be detected, appropriate ICP instrument operating conditions are set, such as: gas flow rate 0.5 L / min, power 1150 W, and element test wavelength selected (depending on the element being tested, such as Ni wavelength 231.60 nm, Co wavelength 100 nm, and Mn wavelength 100 nm). The content of each element is read through the self-analysis function of the ICP testing software, and then the molar percentage of Co element in the cathode material is calculated based on the total molar amount of elements Ni, Co and Mn.

[0052] Before performing ICP testing on the test solution, a standard solution needs to be prepared. Usually, a 1000 mg / L standard solution (a solution containing the element to be tested, which is commercially available) is diluted with deionized water to different concentrations (generally 0, 1 mg / 100mL, 2 mg / 100mL and 3 mg / 100mL) to ensure that the linear correlation coefficient of the standard concentration is ≥0.999.

[0053] In some embodiments, the particle size Dv90 of the cathode material ranges from 4 to 15 μm, and the Dv10 ranges from 0.8 to 3 μm. Adjusting the particle sizes Dv90 and Dv10 of the cathode material to be within these ranges can shorten the lithium-ion transport path, improve lithium-ion transport efficiency, enhance fast-charging performance, and also improve the structural stability and cycle performance of the cathode active material.

[0054] For example, the particle size Dv90 of the positive electrode material is within the range formed by any two values ​​of 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, 15μm or more; and Dv10 is within the range formed by any two values ​​of 0.8μm, 1μm, 1.2μm, 1.4μm, 1.6μm, 1.8μm, 2μm, 2.2μm, 2.4μm, 2.6μm, 2.8μm, 3μm or more.

[0055] This application does not limit the detection method for the particle sizes Dv90 and Dv10 of the positive electrode material; those skilled in the art can perform the detection using conventional techniques. For example, the particle sizes Dv90 and Dv10 of the positive electrode active material can be detected using the following method: 1) Pretreatment: Discharge the battery to the lower limit voltage of 2.5V at 0.33C. Take the positive electrode sheet of the battery in the empty state, soak it in dimethyl carbonate (DMC) solution at 25°C for 4 hours, then take out the electrode sheet and dry it in a vacuum environment. Use a ceramic knife to scrape off the positive electrode material powder on the surface of the electrode sheet. 2) Take the positive electrode material powder and use an instrument (Mastersizer 3000) to measure the particle size distribution according to the particle size distribution laser diffraction method (refer to GB / T19077-2016 for specific steps). The particle size corresponding to the cumulative particle size distribution percentage of 90% is Dv90; the particle size corresponding to the volume particle size distribution of 10% is Dv10.

[0056] In some embodiments, the thickness of the positive electrode material layer is 60~180μm. When the thickness of the positive electrode material layer is within this range, the lithium-ion transport path is shorter, the transport efficiency is higher, and the fast charging performance is better.

[0057] For example, the thickness of the positive electrode material layer is within the range formed by any two of the following values: 60μm, 70μm, 80μm, 90μm, 100μm, 110μm, 120μm, 130μm, 140μm, 150μm, 160μm, 170μm, 180μm.

[0058] This application does not limit the method for detecting the thickness of the positive electrode material layer; those skilled in the art can perform the detection using conventional techniques. For example, the thickness of the positive electrode material layer can be measured using a micrometer.

[0059] In some embodiments, the specific surface area of ​​the positive electrode material ranges from 0.2 to 1.5 m². 2 The specific surface area of ​​the cathode material is 0.2 m² / g. This can shorten the lithium-ion diffusion path and increase reaction sites to improve fast charging capability, while also reducing side reactions and increasing capacity. For example, the specific surface area of ​​the cathode material is 0.2 m² / g. 2 / g, 0.4 m 2 / g, 0.6 m 2 / g, 0.8 m 2 / g、1 m 2 / g, 1.2 m 2 / g, 1.5 m 2 / g or any two of the above values ​​forming a range.

[0060] This application does not limit the method for detecting the specific surface area of ​​the cathode material; those skilled in the art can perform the detection using conventional techniques. For example, the specific surface area of ​​the cathode material can be detected using the following method: 1) Pretreatment: Discharge the battery to the lower limit voltage of 2.5V at 0.33C. Take the positive electrode sheet of the battery in the empty state, soak it in dimethyl carbonate (DMC) solution at 25°C for 4 hours, then take out the electrode sheet and dry it in a vacuum environment. Use a ceramic knife to scrape off the positive electrode material powder on the surface of the electrode sheet. 2) Take the cathode material powder and test it at 25 °C using a nitrogen adsorption instrument according to the BET test method in the national standard GB / T 24533-2019. Specifically, in an environment with a temperature of 25 °C and a humidity of 60%, weigh the total mass of the empty test tube and the stopper. Immerse the sample in absolute ethanol for 4 h and then take it out, put it in an oven at 100 °C and dry it for 0.5 h. Use tweezers to take out the dried sample and put it into the sample tube, and then weigh the total mass of the sample, the test tube and the stopper to obtain the mass of the dried sample. Open the degassing station, put the test tube into the degassing station at 100 °C, purge it with nitrogen (pure nitrogen) for 30 min, cool it for 15 min and then put it on the machine for testing in an environment with a temperature of 25 °C and a humidity of 60%. Use the P / P0 in the range of 0.05-0.25 as the x-axis and P / V(P0-P) as the y-axis to make a curve of the BET equation and perform linear fitting to the slope and intercept of the straight line to calculate the specific surface area of the tested sample.

[0061] In some embodiments, the chemical formula of the lithium nickel cobalt manganese oxide particles is Li q Ni x Co y Mn z O2, where the range of q is 0.9-1.1; 0 < x < 1; 0 < y < 1; 0 < z < 1; x + y + z = 1. Among them, the element M can be selected from at least one of Zr, Ti, Si, Mo, B, Nb, Ta, Al, W, Sr, V, Y, Mg, Ca.

[0062] Exemplarily, x is 0.5, 0.6, 0.7, 0.8, 0.9, 0.95, 0.98 or the range formed by any two of the above numerical values; y is 0.02, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.12, 0.14, 0.16, 0.18, 0.2, 0.22, 0.24, 0.26, 0.28, 0.3 or the range formed by any two of the above numerical values.

[0063] In some embodiments, the element M is also doped in the lithium nickel cobalt manganese oxide particles. In some embodiments, other element R is doped in the lithium nickel cobalt manganese oxide particles, and the bond energy between element R and O is less than or equal to the bond energy between Ni and O. For example, element R is selected from at least one of Ca, F. The doping amount of element R in the lithium nickel cobalt manganese oxide particles can be selected within the range of 300-2000 ppm (mass ratio).

[0064] The preparation method of the lithium nickel cobalt manganese oxide particles is not limited in this application. Those skilled in the art can prepare the lithium nickel cobalt manganese oxide particles according to conventional technical means. Exemplarily, the preparation method of the lithium nickel cobalt manganese oxide particles includes the following steps: The lithium nickel cobalt manganese oxide precursor, lithium source, element M source (if any) and element R source (if any) are mixed and dispersed and then sintered to obtain lithium nickel cobalt manganese oxide particles.

[0065] The lithium nickel cobalt manganese oxide precursor contains Ni, Co and Mn in a target stoichiometric ratio. The lithium nickel cobalt manganese oxide precursor is one or more of Ni, Co and Mn hydroxides, oxides and carbonates, for example, a lithium nickel cobalt manganese oxide precursor is a Ni, Co and Mn hydroxide.

[0066] The lithium nickel cobalt manganese oxide precursor can be obtained by methods known in the art, such as gelation, co-precipitation, or solid-state methods. For example, the preparation method of the lithium nickel cobalt manganese oxide precursor includes the following steps: A soluble salt mixed solution was prepared by dispersing Ni salt, Co salt, and Mn salt in a solvent. The resulting mixed solution, strong alkali solution, and complexing agent solution were simultaneously pumped into a reactor equipped with a stirrer. The pH of the reaction solution was controlled at 11-12, the concentration of the complexing agent was 5-9 g / L, the temperature inside the reactor was 40-60℃, the stirring speed was 300-360 rpm, and the reaction was carried out under an inert atmosphere. After 12-24 hours of reaction, a crystal nucleus slurry was obtained. The solid and liquid were separated, and the obtained solid was washed and dried to obtain the lithium nickel cobalt manganese oxide precursor.

[0067] The Ni salt used includes, but is not limited to, at least one of nickel sulfate, nickel nitrate, nickel chloride, nickel oxalate, and nickel acetate.

[0068] The Co salts used include, but are not limited to, at least one of cobalt sulfate, cobalt nitrate, cobalt chloride, cobalt oxalate, and cobalt acetate; The Mn salts used include, but are not limited to, at least one of manganese sulfate, manganese nitrate, manganese chloride, manganese oxalate, and manganese acetate.

[0069] When dispersing Ni salts, Co salts, and Mn salts in a solvent, the solvent used may include, but is not limited to, water.

[0070] The strong alkaline solution used includes, but is not limited to, at least one of sodium hydroxide and potassium hydroxide.

[0071] The complexing agent solution used includes, but is not limited to, ammonia.

[0072] In the process of preparing the lithium nickel cobalt manganese oxide precursor, the amounts of Ni salt, Co salt and Mn salt used can be selected to satisfy the following: molar amount of element Ni: molar amount of element Co: molar amount of element Mn = (50-98: (0.02-30): (0.08-20).

[0073] In the process of preparing the lithium nickel cobalt manganese oxide particles, the lithium source used includes, but is not limited to, at least one of lithium oxide (Li2O), lithium phosphate (Li3PO4), lithium dihydrogen phosphate (LiH2PO4), lithium acetate (CH3COOLi), lithium hydroxide (LiOH), lithium carbonate (Li2CO3), and lithium nitrate (LiNO3).

[0074] In the process of preparing the lithium nickel cobalt manganese oxide particles, the amount of lithium source used satisfies the following: the molar amount of Li element in the lithium source : the sum of the molar amounts of Ni salt, Co salt, Mn salt, element M source (if any) and element R source (if any) of Ni, Co, Mn, M and R elements = (1.00-1.07):1.

[0075] During the preparation of the lithium nickel cobalt manganese oxide particles, the sintering atmosphere is an oxygen-containing atmosphere, such as an air atmosphere or an oxygen atmosphere.

[0076] In some embodiments, the sintering process for preparing the lithium nickel cobalt manganese oxide particles is as follows: The temperature is raised to T1, and the first heat-holding sintering is carried out at this temperature. The temperature is raised to T2, and sintering is carried out in the second heat preservation stage at this temperature; Cool down to room temperature.

[0077] Among them, T1 is in the range of 450-550℃, and the sintering time of the first heat preservation section is 2-6h; For T2, the sintering time of the second heat preservation section is 10-20 hours within the range of 700-1000℃. The heating rates mentioned above are each independently selected from 2 to 10 °C / min.

[0078] When mixing and dispersing the lithium nickel cobalt manganese oxide precursor, lithium source, element M source (if any), and element R source (if any), a ball mill or high-speed mixer can be used. Element M source can be an oxide and / or salt of element M; element R source can be an oxide and / or salt of element R.

[0079] In addition, lithium nickel cobalt manganese oxide particles can be coated. Specifically, a dry coating method (high-temperature solid-state method) is used to coat the surface of the lithium nickel cobalt manganese oxide particles with a coating material, so that the surface of the lithium nickel cobalt manganese oxide particles is partially or completely covered with a coating layer formed by the coating material. In one embodiment, the coating material includes at least one of tungsten oxide, boron oxide, and aluminum oxide.

[0080] In some embodiments, the mass percentage of lithium nickel cobalt manganese oxide particles in the cathode material is 60% to 98.5%, such as a range formed by any two values ​​of 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 98.5% or higher.

[0081] In some embodiments, the positive electrode active material further includes at least one of lithium iron phosphate and lithium manganese iron phosphate to improve the overall stability of the positive electrode sheet. In one embodiment, the lithium iron phosphate content in the positive electrode material layer accounts for 5% to 15% of the total mass of the positive electrode material, such as within the range formed by any two values ​​of 5%, 8%, 10%, 12%, 15%, or higher. In one embodiment, the lithium manganese iron phosphate content in the total mass of the positive electrode material accounts for 5% to 40%, such as within the range formed by any two values ​​of 5%, 10%, 20%, 30%, 35%, 40%, or higher.

[0082] In addition to the aforementioned positive electrode active material, the positive electrode material also includes a conductive agent and a binder.

[0083] The conductive agent in the cathode material is used to provide conductivity. Any conductive agent can be used without particular limitation, as long as it has suitable electronic conductivity and does not significantly cause adverse chemical changes in the battery. For example, the conductive agent in the cathode material includes, but is not limited to, at least one of carbon nanotubes, carbon black, graphite, activated carbon, carbon fibers, mesoporous carbon, and fullerenes. Carbon fibers include, for example, carbon nanofibers; carbon black includes, for example, acetylene black, SP (Super P), and Ketjen black.

[0084] In some embodiments, the mass percentage of the conductive agent in the positive electrode material is 0.5% to 2.0%, such as 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2.0%, or any range formed by any two of the above values.

[0085] The binder in the cathode material is used to improve the adhesion between cathode active material particles and the adhesion between the cathode active material and the cathode current collector. Any binder can be used without particular limitation, as long as it has suitable adhesive properties and does not significantly cause adverse chemical changes in the battery. For example, binders in the cathode material include, but are not limited to, fluorinated polyolefin binders, including but not limited to polyvinylidene fluoride (PVDF), PVDF copolymers, or their modified derivatives (e.g., modified with carboxylic acids, acrylic acid, acrylonitrile, etc.).

[0086] In some embodiments, the mass percentage of binder in the cathode material is 1% to 4%, such as 1%, 1.2%, 1.5%, 1.8%, 2%, 2.2%, 2.5%, 2.7%, 3%, 3.2%, 3.5%, 3.8%, 4%, or any range formed by any two of the above values.

[0087] The positive electrode material layer can be disposed on one side of the positive electrode current collector or on both sides of the positive electrode current collector.

[0088] This application does not impose any particular restrictions on the positive electrode current collector, as long as it is conductive and will not cause adverse chemical changes in the battery. For example, it may use at least one of the following materials: aluminum, nickel, titanium, stainless steel, sintered carbon; or aluminum or stainless steel that has been surface treated with at least one of carbon, nickel, titanium, silver, etc.

[0089] In some embodiments, the areal density of the positive electrode is 3.2-3.8 g / m³. 2 For example, 3.2 g / m 2 3.3 g / m 2 3.4 g / m 2 3.5 g / m 2 3.6 g / m 2 3.7 g / m 2 3.8 g / m 2 Or the range formed by any two of the above values.

[0090] In some embodiments, the compaction density of the positive electrode sheet is 180-700 g / m³. 3 For example, 180 g / m 3 200 g / m 3 300 g / m 3 400 g / m 3 500 g / m 3 600 g / m 3 700 g / m 3 Or the range formed by any two of the above values.

[0091] In some embodiments, the porosity of the positive electrode is 15% to 40%, such as 15%, 20%, 25%, 30%, 35%, 40%, or any range formed by two of the above values.

[0092] The positive electrode sheet of this application can be prepared according to conventional methods in the art. For example, the positive electrode active material, conductive agent and binder are dispersed in a solvent to obtain a positive electrode slurry, and then the positive electrode slurry is coated on at least one side of the positive electrode current collector. After drying, cold pressing, slitting and other processes, the positive electrode sheet is obtained. The solvent in the positive electrode slurry includes, but is not limited to, at least one of N-methylpyrrolidone (NMP) and deionized water.

[0093] Battery This application also provides a battery including the aforementioned positive electrode. The battery includes a cell and a casing. The cell includes a positive electrode, a negative electrode, an electrolyte (if present, it can also be a solid electrolyte), and a separator (if present, solid-state batteries do not have a separator). The casing is a component used to provide a space to house the cell and other components. The casing generally includes a body with an opening at at least one end and a receiving cavity. The opening of the casing can be closed by a cover plate to seal and isolate the internal environment of the cell from the external environment.

[0094] Shell material / composition: The materials of the casing include, but are not limited to, copper, iron, aluminum, stainless steel, aluminum alloy, plastic, and aluminum-plastic film.

[0095] In some embodiments, the battery further includes an electrolyte with a viscosity of 1–10 mPa·s at 25°C, such as 1 mPa·s, 2 mPa·s, 3 mPa·s, 4 mPa·s, 5 mPa·s, 6 mPa·s, 7 mPa·s, 8 mPa·s, 9 mPa·s, 10 mPa·s, or any range formed by two of the above values. In one embodiment, the viscosity of the electrolyte at 25°C is 2–5 mPa·s.

[0096] Controlling the viscosity of the electrolyte at 25°C within the range of 1~10 mPa·s, especially within the range of 2~5 mPa·s, is more conducive to wetting the cathode material and promoting lithium ion extraction.

[0097] This application does not limit the method for detecting the viscosity of the electrolyte; those skilled in the art can perform the detection using conventional techniques. For example, the viscosity of the electrolyte can be detected using the following method: 1) Electrolyte Collection: The battery under test is discharged using a battery charge / discharge device. Discharge conditions: current 0.3C, discharge to the lower limit voltage 2.5V. The battery is disassembled and the electrolyte collected in a glove box (H2O≤0.1ppm, O2≤0.1ppm). There are three methods for collecting the electrolyte: After removing the battery cover, ① if there is free electrolyte, collect it into a 5mL sample tube using a pipette and seal it with sealing tape to prevent leakage. ② if there is no free electrolyte, a hydraulic press (Beijing Heng'ao Technology Co., Ltd.'s FY-30 hydraulic press) can be used to continuously pressurize until free electrolyte appears. Collect the electrolyte into a sample tube and seal it. ③ Add an appropriate amount of dichloromethane extractant to the battery and record the dichloromethane content. After adding dichloromethane, put the battery into an aluminum-plastic bag and seal it with a heat sealer. Transfer it to an ultrasonic oscillator and oscillate for 12 hours to allow the electrolyte in the electrode to mix thoroughly with the dichloromethane. Then, use a pipette to draw the mixture of dichloromethane and electrolyte into a 5mL sample tube and seal the sample tube with sealing glue. 2) Remove the electrolyte and test it using a Cambridge viscometer. The Cambridge viscometer is designed based on electromagnetic oscillation viscosity detection technology and uses a magnetically levitated probe for viscosity measurement. Specifically, place the electrolyte in a beaker and control the sample temperature at 25°C for testing. Read the value after the display value stabilizes.

[0098] In some embodiments, the electrolyte further comprises a solvent, which includes linear esters and cyclic esters; based on the total mass of the electrolyte, the mass percentage of linear ester solvent is 15% to 50%, and the mass percentage of cyclic ester solvent is 25% to 35%. Linear ester solvents can reduce the viscosity of the electrolyte, which is beneficial for ion migration and improves lithium-ion transport efficiency; cyclic ester solvents have strong polarity and can dissociate Li from the lithium salt. + It reacts with anions to form free lithium ions, thereby improving the ionic conductivity of the electrolyte. A mixture of linear and cyclic esters is used to achieve the optimal balance between "high degree of dissociation" and "low viscosity," resulting in high ionic conductivity and improved battery fast-charging performance.

[0099] In some embodiments, the linear esters include linear carbonates. In some embodiments, the linear esters include at least one selected from dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl acetate (EA), methyl methyl carbonate (EMC), methyl propionate (MP), and methyl formate (MA).

[0100] In some embodiments, the cyclic esters include cyclic carbonates. In some embodiments, the cyclic ester solvent includes at least one of ethylene carbonate (EC), propylene carbonate (PC), and fluoroethylene carbonate (FEC).

[0101] The electrolyte further includes an electrolyte. In one embodiment, the electrolyte includes a lithium salt. Exemplarily, the lithium salt includes, but is not limited to, at least one of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium difluorooxalate borate (LiDFOB), lithium dioxalate borate (LiBOB), lithium difluorodioxalate phosphate (LiDFOP), lithium tetrafluorooxalate phosphate (LiTFOP), lithium hexafluoroarsenate (LiAsF6), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), and lithium difluorophosphate (LiPO2F2). The concentration of the electrolyte in the electrolyte can be selected as 0.5~5 mol / L.

[0102] In some embodiments, the electrolyte contains additives. Exemplary examples include, but are not limited to, at least one of unsaturated ester additives (such as at least one of VC, FEC, VEC, CC, AEC, VA, etc.), sulfur-containing additives (such as at least one of PS, ES, DES, PES, DMS, VES, DTD, TMS, FPS, SPA, etc.), lithium salt additives (such as at least one of LiBOB, LiODFB, LiTFOP, LiPO2F2, LiTFSI, LiFSI, LiBODFP, etc.), inorganic compound additives (such as at least one of CO2, SO2, Na2CO3, Na2SO3, K2CO3, etc.), and other additives (silane additives, GBL and its derivatives, ionic liquids, acid anhydride additives, and nitrogen-containing additives).

[0103] In some embodiments, the electrolyte comprises at least one of vinylene carbonate (VC), fluorovinylene carbonate (FEC), and propylene sulfite (PS). In some embodiments, the battery further comprises a separator. In one embodiment, the permeability of the separator is in the range of 50-350 s / 100 mL. When the permeability of the separator is within this range, the lithium-ion transport rate can be improved, thus enhancing fast-charging performance. For example, the air permeability of the diaphragm is 50 s / 100 mL, 70 s / 100 mL, 100 s / 100 mL, 120 s / 100 mL, 140 s / 100 mL, 160 s / 100 mL, 180 s / 100 mL, 220 s / 100 mL, 240 s / 100 mL, 260 s / 100 mL, 280 s / 100 mL, 300 s / 100 mL, 320 s / 100 mL, 350 s / 100 mL, or any range formed by two of the above values.

[0104] This application does not limit the method for testing the air permeability of the diaphragm; those skilled in the art can perform the test using conventional techniques. For example, the air permeability of the diaphragm can be tested using the following method: The battery was discharged at 0.33C to the lower limit voltage of 2.5V. Then the empty battery was disassembled, the separator was removed, and the separator was soaked in dimethyl carbonate (DMC) solution for 2 hours. The separator was then removed and dried. According to the requirements of GB / T36363-2018, the air permeability test requirements are: at a test temperature of 25℃ and a normal pressure (1.01325×10⁻⁶), the air permeability test is performed at a pressure of 1.01325×10⁻⁶. 5 In an environment of 1.21 kPa, the time required for 100 mL of air to pass through a 6.45 square centimeter membrane under a pressure of 1.21 kPa applied by the BTY-G3 battery separator permeability tester.

[0105] The separator can be any of the battery-compatible separator materials available in the art. Exemplarily, the separator includes, but is not limited to, at least one of glass fiber, nonwoven fabric, polyethylene (PE), and polypropylene (PP). A coating may also be provided on the separator surface. This coating can be an inorganic coating and / or an organic coating, wherein the inorganic coating material includes at least one of alumina, silicon oxide, titanium oxide, magnesium oxide, zirconium oxide, and boehmite; and the organic coating includes at least one of aramid coating and polyvinylidene fluoride (PVDF) coating.

[0106] In some embodiments, the battery also includes a negative electrode.

[0107] In some embodiments, the areal density of the negative electrode sheet is 60~300 g / m³. 2 For example, the areal density of the negative electrode is 60 g / m³. 2 80 g / m 2 100 g / m 2 120 g / m 2 140g / m 2 160 g / m 2 180 g / m 2 200 g / m 2 220g / m 2 240 g / m 2 260 g / m 2 280 g / m 2 300 g / m 2 Or the range formed by any two of the above values.

[0108] In some embodiments, the compaction density of the negative electrode sheet is 1.0~1.7 g / m³. 3 For example, the compaction density of the negative electrode sheet is 1.0 g / m³.3 1.1 g / m 3 1.2 g / m 3 1.3 g / m 3 1.4 g / m 3 1.5 g / m 3 1.6 g / m 3 1.7 g / m 3 Or the range formed by any two of the above values.

[0109] In some embodiments, the porosity of the negative electrode is 10% to 50%. For example, the porosity of the negative electrode is 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, or any range formed by any two of the above values.

[0110] This application does not limit the methods for detecting the areal density and compaction density of the positive and negative electrode sheets; those skilled in the art can perform the detection using conventional techniques. For example, the areal density and compaction density of the positive and negative electrode sheets can be detected using the following methods: 1) Pretreatment: Discharge the battery at 0.33C to the lower limit voltage of 2.5V, take out the empty battery, disassemble the electrode, soak the electrode in dimethyl carbonate (DMC) solution at 25℃ for 4 hours, take it out and air dry; 2) Use a punching machine to punch the dried electrode sheet into circular pieces of a fixed area, denoted as S0. Take three circular pieces as parallel samples and weigh them using an electronic balance. Take the average value and record it as M1. Use a micrometer to measure the thickness of the active material layer in each of the three circular pieces (i.e., the total thickness minus the current collector), and take the average value and record it as H. Then, add an appropriate amount of deionized water to each of the three circular pieces, gently wipe off the coating on the circular pieces with lint-free paper to expose the current collector, and let them stand at room temperature (or dry) for 10 minutes. After the current collector is dry, weigh the current collectors of the three pieces and take the average value and record it as M0. Calculate the compaction density of the electrode sheet A = (M1 - M0) / (H × S0) according to the following formulas: surface density = (M1 - M0) / S0.

[0111] This application does not limit the method for detecting the porosity of the positive and negative electrode sheets; those skilled in the art can perform the detection using conventional techniques. For example, the porosity of the positive and negative electrode sheets can be detected using the following methods: 1) Pretreatment: Discharge the battery at 0.33C to the lower limit voltage of 2.5V, take out the empty battery, disassemble the electrode, soak the electrode in dimethyl carbonate (DMC) solution at 25℃ for 2 hours, take it out and air dry; 2) Use a punching machine to cut the dried electrode sheet into round pieces with a diameter of 12mm. Simultaneously, use a thickness gauge to measure the thickness of the electrode sheet and the current collector, respectively, as h1 and h2. Weigh the material using a balance with an accuracy of 0.00001g, and record the mass as m1. According to the formula v=πr 2 Calculate the volume v of the cut electrode by multiplying (h1-h2); Immerse the electrode in a sealed container with a certain volume of hexadecane for 1 hour (the volume of hexadecane in the sealed solution is not required, but the amount must be sufficient to completely submerge the electrode); after 1 hour, remove the electrode with tweezers and place it on filter paper to absorb dry until constant weight (generally, 1 hour is sufficient to absorb dry to constant weight). Weigh it using a balance and record the mass as m2. Calculate the porosity using the following formula: Porosity = X / v × 100%, where X = (m2-m1) / ρ, and ρ is the density of hexadecane, 0.7734 g / cm³. 3 .

[0112] In some embodiments, the negative electrode sheet includes a negative electrode material, the negative electrode material includes a negative electrode active material, and the negative electrode active material includes at least one of graphite and silicon-based materials.

[0113] In some embodiments, the particle size Dv50 of the negative electrode material is 4~25μm, such as 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, 18μm, 20μm, 22μm, 25μm, or any range formed by two of the above values. In one embodiment, the particle size Dv50 of the negative electrode material is 5~10μm.

[0114] Controlling the particle size Dv50 of the negative electrode material within the range of 4~25μm, especially within the range of 5~10μm, is beneficial for ion migration and can improve the fast charging performance of the battery.

[0115] This application does not limit the method for detecting the particle size Dv50 of the negative electrode material; those skilled in the art can perform the detection using conventional techniques. For example, the particle size Dv50 of the negative electrode material can be detected using the following method: 1) Pretreatment: Discharge the battery to the lower limit voltage of 2.5V at 0.33C. Take the negative electrode sheet of the battery in the empty state, soak it in dimethyl carbonate (DMC) solution at 25°C for 4 hours, then take out the electrode sheet and dry it in a vacuum environment. Use a ceramic knife to scrape off the negative electrode material powder on the surface of the electrode sheet. 2) Take the negative electrode material powder and use an instrument (Mastersizer 3000) to measure the particle size distribution according to the particle size distribution laser diffraction method (specific steps refer to GB / T19077-2016). The particle size corresponding to the cumulative particle size distribution percentage reaching 50% is Dv50.

[0116] In some embodiments, the mass percentage of the negative electrode active material in the negative electrode material is 90% to 98%, such as 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or any range formed by any two of the above values.

[0117] The negative electrode material may also contain conductive agents, and / or binders, and / or dispersants.

[0118] The conductive agent in the negative electrode material is used to provide conductivity. Any conductive agent can be used without particular limitation, as long as it has suitable electronic conductivity and does not significantly cause adverse chemical changes in the battery. For example, the conductive agent in the negative electrode material includes, but is not limited to, at least one of carbon nanotubes, carbon black, graphite, carbon fibers, activated carbon, mesoporous carbon, and fullerenes, wherein carbon fibers are, for example, carbon nanofibers; and carbon black is, for example, SP, acetylene black, Ketjen black, etc.

[0119] In some embodiments, the mass percentage of the conductive agent in the negative electrode material is 0 to 5%, such as 0, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, or any range formed by any two of the above values.

[0120] The binder in the negative electrode material is used to improve the adhesion between the negative electrode active material particles and the adhesion between the negative electrode active material and the negative electrode current collector. Any binder can be used without particular limitation, as long as it has suitable adhesive properties and does not significantly cause adverse chemical changes in the battery. For example, the binder in the negative electrode material includes, but is not limited to, at least one of carboxymethyl cellulose (CMC), styrene-butadiene rubber (SBR), polyacrylic acid (PAA), polyvinylidene fluoride, polytetrafluoroethylene, polyvinyl butyral, and aqueous acrylic resin.

[0121] In some embodiments, the mass percentage of binder in the negative electrode material is 1.5% to 5%, such as 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, or any range formed by any two of the above values.

[0122] The dispersant in the negative electrode material is used to improve the dispersibility of the negative electrode active material. Any dispersant can be used without particular limitation, as long as it has suitable dispersibility and does not significantly cause adverse chemical changes in the battery. For example, the dispersant in the negative electrode active material layer includes, but is not limited to, at least one of carboxymethyl cellulose (CMC), styrene-butadiene rubber (SBR), and hydrogenated styrene-butadiene rubber (H-SBR).

[0123] In some embodiments, the mass percentage of dispersant in the negative electrode material is 0.3% to 1.5%, such as 0.3%, 0.5%, 0.8%, 1%, 1.2%, 1.5%, or any range formed by any two of the above values.

[0124] The negative electrode material can be composited on one side of the negative electrode current collector or on both sides of the negative electrode current collector.

[0125] This application does not impose any particular restrictions on the negative electrode current collector, as long as it is conductive and will not cause adverse chemical changes in the battery. For example, it may use at least one of the following materials: copper, stainless steel, aluminum, nickel, titanium, sintered carbon, aluminum-cadmium alloy; or copper or stainless steel that has been surface-treated with at least one of carbon, nickel, titanium, silver, etc.

[0126] In some embodiments, the battery includes a casing and a cell, wherein the casing is cylindrical or quadrangular prism-shaped. When the casing is cylindrical, its outer shape is cylindrical with an internal cylindrical cavity, and the material can be aluminum, aluminum alloy, or composite metal materials, etc.; when the casing is quadrangular prism-shaped, its outer shape is a quadrangular prism-like cuboid with an internal rectangular cavity, and the material can be aluminum, aluminum alloy, or composite metal materials, etc.

[0127] In some embodiments, the housing is cylindrical, with a diameter ranging from 15 to 50 mm and a height ranging from 50 to 250 mm. For example, the housing diameter is 15 mm, 20 mm, 25 mm, 30 mm, 35 mm, 40 mm, 45 mm, 50 mm, or any two of the above values; the height is 50 mm, 80 mm, 100 mm, 120 mm, 150 mm, 180 mm, 200 mm, 220 mm, 250 mm, or any two of the above values.

[0128] In some embodiments, the casing is cylindrical, the ratio of the cell diameter to the casing diameter is ≥0.9, and the Fd3m phase thickness of the positive electrode after 200 cycles is 0.8~15nm. When the ratio of the cell diameter to the casing diameter is ≥0.9 (e.g., 0.9, 0.95, 1, or any two of the above values ​​within a range), the remaining space inside the battery is small, and the casing can store less electrolyte, resulting in a decrease in the ability to transport lithium ions. By controlling the Fd3m phase thickness of the positive electrode after 200 cycles within the above range, the transport of lithium ions can be improved.

[0129] This application does not limit the method for detecting the Fd3m phase thickness after the positive electrode sheet has undergone 200 cycles; those skilled in the art can perform the detection using conventional techniques. For example, the aforementioned method can be used for detection.

[0130] The tab is located on one side of the positive / negative current collector and is separately or integrally formed with the current collector. It is electrically connected to the current collector to conduct the current on the corresponding current collector. The tab is made of a metal material with good conductivity (such as copper, aluminum, or nickel).

[0131] In some embodiments, the casing is cylindrical, and the battery includes tabs and cells. The tabs include positive and negative tabs, both extending from opposite ends of the cell. These two ends are located along the thickness or length of the cell. The value of b ranges from 0.002 to 0.06. When the positive and negative tabs are extended from opposite ends of the cell, the current path is long, resulting in high current transmission resistance. By controlling b within this range, lithium-ion transmission efficiency can be improved, enhancing fast-charging performance.

[0132] In some embodiments, the casing is cylindrical, and the battery includes tabs and a cell. The tabs include a positive tab and a negative tab, both of which are led out from the same end of the cell.

[0133] In some embodiments, the battery cell is a wound cell, which includes a winding radius (R-angle), and the value of b ranges from 0.002 to 0.06. Wound cells are typically manufactured by winding continuous positive and negative electrode sheets and a separator, with the separator located between adjacent positive and negative electrode sheets. The R-angle specifically refers to the arc-shaped portion formed at both ends of the cell's length direction after the positive, negative, and separator sheets are wound and then hot-pressed. When a wound cell has a winding R-angle, electrolyte wetting is difficult, and the winding is compact. By controlling b within this range, lithium-ion transport efficiency can be improved, and fast-charging performance can be enhanced.

[0134] In some embodiments, the radius of the winding R-angle is in the range of 0.5-5 mm. For example, the radius of the winding R-angle is 0.5 mm, 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, or any range formed by any two of the above values.

[0135] In some embodiments, the battery cell in the battery is a laminated cell. A laminated cell refers to a cell manufactured by laminating positive electrode plates, negative electrode plates, and a separator using a lamination process. The positive and negative electrode plates are separated by a separator, and adjacent positive and / or negative electrode plates within the cell have a discontinuous structure. The lamination process includes methods such as layering or Z-shaped folding.

[0136] In some embodiments, the battery is a solid-state battery, and the range of b is 0.0015~0.06. A solid-state battery refers to a battery system that uses an all-solid-state electrolyte or a gel electrolyte. Because the conventional liquid electrolyte is eliminated, the wetting effect of the electrolyte on the positive electrode is worse. The contact between the solid-state battery electrode and the electrolyte is a solid-solid interface, which increases the lithium-ion transport impedance and reduces the lithium-ion transport capability. By controlling b within this range, the lithium-ion transport efficiency can be improved, and fast-charging performance can be enhanced.

[0137] In some embodiments, the solid-state battery includes an electrolyte, which includes a sulfide solid-state electrolyte.

[0138] In one embodiment, the sulfide solid electrolyte is selected from one or more of lithium phosphorus sulfide chloride, lithium germanium phosphorus sulfide, lithium phosphorus sulfide derivatives, and lithium germanium phosphorus sulfide derivatives.

[0139] In some embodiments, the battery includes a casing, which includes at least one of an aluminum-plastic film and a metal casing.

[0140] Aluminum-plastic film is a multi-layer packaging material made of aluminum foil and plastic. From the inside out, aluminum-plastic film typically includes a heat-sealing layer, a barrier layer, and a substrate / protective layer stacked in sequence.

[0141] Among them, the heat-sealing layer material is cast polypropylene (PP) or modified PP film; Function: Heat sealing, which means that under heat and pressure, the layer melts and firmly bonds itself or other PP materials to form a tight seal, ensuring the integrity of the packaging.

[0142] Barrier layer material: aluminum foil; Function: Barrier properties: Isolates moisture and oxygen, preventing external vapors and oxygen from entering the packaging, while also preventing internal substances (such as electrolyte) from evaporating, thus ensuring battery life and safety; Electromagnetic interference protection: It can shield electromagnetic waves; Light-blocking properties: Blocks light and protects photosensitive materials.

[0143] Substrate / protective layer material: usually nylon film or polyester film.

[0144] A metal casing is a rigid outer shell made of metal materials (such as aluminum, steel, nickel alloys, etc.) used to encapsulate battery cells and electrolytes (liquid, gel, or solid). Its core functions are to fix the cell structure, isolate external air and moisture, prevent electrolyte leakage, and also provide mechanical protection and heat dissipation. It is a key encapsulation component of the battery.

[0145] In some embodiments, the metal shell is selected from at least one of aluminum shell, steel shell, titanium shell, etc., wherein the material of the aluminum shell can be aluminum metal or aluminum alloy, the material of the steel shell can be at least one of stainless steel, nickel-plated steel, carbon steel, etc., and the material of the titanium shell can be titanium metal or titanium alloy.

[0146] Electrical appliances This application also provides an electrical device, including a battery device comprising the battery. The battery device can serve as the operating power source for the electrical device, or as the driving power source, replacing or partially replacing fuel oil or natural gas to provide driving power for the device. The electrical device encompasses numerous technical fields, including energy storage devices, electric ships, aircraft, laptops, power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, and aerospace.

[0147] An electrical appliance may meet at least one of the following conditions: (1) The electrical device includes a battery pack. There are multiple battery packs. Multiple battery packs can be connected in series, in parallel, or in a mixed manner. A mixed manner means that multiple battery packs are connected in both series and parallel.

[0148] (2) The battery device is a cluster-level battery structure formed by multiple battery packs connected in series, wherein the number of battery packs in each cluster is strictly configured according to the voltage and capacity requirements. Specifically, the battery unit of the battery device includes multiple batteries, some of which are connected in series to form a cluster that meets the preset power supply voltage requirements, and at least one spare battery among the multiple batteries is bypassed.

[0149] (3) The battery device may include: battery cells and switching control unit.

[0150] The present application is further illustrated below with specific embodiments: Example 1 This embodiment provides a lithium-ion battery, and the specific preparation method is as follows: (1) Preparation of lithium nickel cobalt manganese oxide particles Ni salt (NiSO4), Co salt (CoSO4), and Mn salt (MnSO4) were dissolved in water to prepare a soluble salt mixed solution. The resulting mixed solution, sodium hydroxide solution, and ammonia water were simultaneously pumped into a first reaction vessel equipped with a stirrer. The pH value of the reaction solution was controlled at 11.5 and the ammonia concentration at 7.7 g / L. The temperature inside the reaction vessel was 45℃, and the stirring pump speed was 325 r / min. The reaction process was carried out under an inert atmosphere of nitrogen protection. After 12 hours of reaction, a crystal nucleus slurry was obtained. After filtration, the obtained solid was washed and dried to obtain the lithium nickel cobalt manganese oxide precursor. The lithium nickel cobalt manganese oxide precursor, lithium hydroxide (lithium source), and zirconium oxide (doping element source) were mixed and dispersed and then sintered in a muffle furnace. The temperature was increased to 550°C at a rate of 5°C / min, and the first holding period was carried out at this temperature for 4 hours. The temperature was then increased to 900°C at a rate of 5°C / min, and the second holding period was carried out at this temperature for 19 hours. The mixture was then allowed to cool naturally to obtain lithium nickel cobalt manganese oxide particles. Using an ALD atomic deposition instrument, alumina powder was used as the coating material to deposit alumina on the obtained lithium nickel cobalt manganese oxide particles, resulting in lithium nickel cobalt manganese oxide particles with alumina coating on the surface, which is the positive electrode active material.

[0151] The above-mentioned Ni salts, Co salts, and Mn salts are classified according to LiNi x Co y Mn z The molar ratios of Ni, Co, and Mn elements in the chemical formula of O2 (see Table 1 for specific chemical formula) are weighed. Based on the sum of the molar amounts of Ni, Co, Mn salts and dopant elements (Zr in this example) from the sources of Ni, Co, Mn salts and dopant elements, the molar amount of Li in the lithium source is 1.05 times. Table 1 shows the types of element M, the forms in which each element exists, the mass ratio of each element, and the mass percentage of element M in lithium nickel cobalt manganese oxide particles.

[0152] (2) Preparation of positive electrode sheet The obtained positive electrode active material was mixed with conductive agent acetylene black and binder PVDF at a mass ratio of 97:1.5:1.5, and solvent NMP was added. The mixture was stirred in a vacuum mixer to obtain positive electrode slurry. The positive electrode slurry is coated on both sides of the positive electrode current collector aluminum foil, dried, cold-pressed, and cut to obtain the positive electrode sheet; the mass percentage of element M in the positive electrode material layer (i.e. the sum of the mass percentages of each element M) is shown in Table 1.

[0153] (3) Preparation of negative electrode sheet The negative electrode active material artificial graphite, conductive agent acetylene black, dispersant CMC and binder SBR are mixed in a mass ratio of 96:2:1:1, deionized water is added, and the mixture is stirred in a vacuum mixer to obtain a negative electrode slurry. The negative electrode slurry is coated on both sides of the negative electrode current collector copper foil, and then cold-pressed and slit to obtain a negative electrode sheet.

[0154] (4) Preparation of electrolyte Ethylene carbonate (EC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC) were mixed in a volume ratio of 1:1:1 to obtain an organic solvent. The dried lithium salt LiPF6 was dissolved in the obtained organic solvent to prepare an electrolyte with a LiPF6 concentration of 1 mol / L.

[0155] (5) Preparation of lithium-ion batteries The positive electrode, separator (PE), and negative electrode are stacked in sequence, with the separator acting as an isolation between the positive and negative electrode sheets, and then wound to obtain a bare cell. The bare battery cell is placed in an outer packaging shell (aluminum-plastic film, shell shape shown in Table 1), with the positive and negative tabs led out from the same end of the cell. After drying, electrolyte is injected, and the battery undergoes vacuum sealing, settling, formation, and shaping processes to obtain a lithium-ion battery. The formation process is as follows: After standing at 25℃ for 24 hours, the glass is placed in a glass clamp with a clamping pressure of 0.4~0.6MPa; at 25℃, Let stand for 10 minutes, then charge at a rate of 0.025C, with a cutoff voltage of 3V; Let stand for 10 minutes, then charge at a rate of 0.05C, with a cutoff voltage of 3.2V; Let stand for 10 minutes, then charge at a rate of 0.25C, with a cutoff voltage of 3.6V; Let stand for 10 minutes, then charge at a rate of 0.33C, with a cutoff voltage of 3.75V; Let stand for 10 minutes, then charge at a 0.1C rate until the cutoff voltage reaches 3.95V. Finish.

[0156] Examples 2-32 and Comparative Examples 1-5 These examples and comparative examples all provide a lithium-ion battery, and the preparation method is similar to that of Example 1, except that: In step (1), the chemical formula of lithium nickel cobalt manganese oxide particles, the ammonia concentration, pH value and stirring speed of the reaction solution, the type of element M, the form of each M, the mass ratio of each M and the mass percentage of element M in lithium nickel cobalt manganese oxide particles, the sintering temperature and time of the second heat preservation section, and the oxygen content in the sintering atmosphere are shown in Table 1. In step (4), the form of the electrolyte is shown in Table 1. If it is a sulfide solid electrolyte, then it is specifically lithium phosphorus sulfur chloride with the structural formula Li6PS5Cl. In step (5), the casing shape is shown in Table 1. In addition, if it is a solid-state battery, then this step is as follows: The negative electrode and solid electrolyte are combined, and the combined negative electrode, solid electrolyte and positive electrode are stacked and hot-pressed to form a single electrode unit. Multiple electrode units are stacked in sequence to form a cell, hot-pressed, bagged and vacuum-sealed; isostatic pressing is performed at an isostatic pressure of 600MPa, then the cell is removed from the bag, the aluminum-plastic film is punched, the tabs are welded, the opening of the aluminum-plastic film is welded, vacuum is applied, and the cell is left to stand and be calibrated to obtain a solid-state battery.

[0157] Table 1 The following methods were used to test the batteries of each embodiment and comparative example: (1) Testing of fast charging performance Obtain a three-electrode soft-pack battery. Preparation of the three-electrode copper wire: Wrap the copper wire around the fixed copper foil surface, evenly adhering both ends of the wire to the foil. With the end of the foil (the neatly cut end of the double-sided tape) facing down, roll it into a semi-circle and place it in a 500mL beaker. Add sulfuric acid (a 1:1 volume ratio of pure water and 98% concentrated sulfuric acid) to immerse the wire, ensuring the immersion depth exceeds the top of the double-sided tape by 12mm. Immerse in the sulfuric acid for 4 hours, then remove. Clean the bottom immersed area with anhydrous ethanol, let it stand for 5 minutes, and then proceed with subsequent processing. Prepare 1.2mol / L dilute hydrochloric acid (37wt% concentrated hydrochloric acid diluted 10 times with deionized water). Immerse the copper foil with the attached copper wire in the dilute hydrochloric acid and acid wash for 15 minutes. Remove the acid-washed copper wire and place it in anhydrous ethanol, then clean it in an ultrasonic cleaner for 10-15 minutes. Transfer the copper wire to a room with humidity less than 1.2% for later use. Assembly and Formation: Prepare the required positive and negative electrode sheets and copper wires. Stack the electrode sheets in the following order: negative electrode sheet, separator, copper wire, separator, positive electrode sheet, separator, negative electrode sheet. The positive electrode sheet should be placed in the center of the negative electrode sheet, and the negative electrode sheets should be completely aligned. After stacking, peel off the outermost negative electrode sheet. Position the end of the copper wire (processed end) 32±5mm from the top edge of the cell and 40.5±5mm to the left and right. Add another 81×81mm² separator, then place the negative electrode sheet on top. After arranging the copper wire, the copper wire should be 11.5mm from each side of the electrode tab. After the separator automatically winds up one and a half times, roll it up and apply adhesive to fix the separator in place. The outermost separator should be tightly wrapped without any obvious looseness, and at least 110mm of copper wire should be exposed. The copper wire is transferred using a soldering iron (soldering temperature 300℃, time 5-10s). During ultrasonic welding, the battery cell is handled gently to prevent the copper wire from breaking during transport, resulting in a bare battery cell. The bare battery cell is then placed in an outer packaging shell, dried, and injected with electrolyte. After vacuum sealing, settling, and formation, the formation process follows the steps given above. Then, the following steps are performed: the battery is charged at a constant current of 0.33C to 4.25V, charged at a constant voltage until the current is less than or equal to 0.05C, and discharged at 0.33C to the lower limit voltage of 2.5V. These steps are repeated 3 times, and the capacity discharged in the third cycle is used as the basis for the calculation. Let C be the battery discharge capacity; let it rest for 10 minutes, discharge at 1C to 2.5V, let it rest for 10 minutes, charge at 0.33C to 10% SOC; then perform a 0.4C down-charging step, and charge at rates of 4C, 3.6C, 3.2C, 2.8C, 2.4C, 2.0C, 1.6C, 1.2C, 0.8C, and 0.4C in sequence. The cutoff condition for each charge is to charge to the upper limit voltage of 4.25V or the auxiliary voltage of 0mV; record the charging time within the state of charge range of 10% SOC (10%×C) to 80% SOC (80%×C), which is the fast charging time.

[0158] (2) Capacity testing At 25℃, the formed battery is charged at a constant current of 0.33C to the upper limit voltage of 4.25V, then charged at a constant voltage to the cutoff current of 0.05C, and then discharged at 0.33C to the lower limit voltage of 2.5V. This is one cycle, and the charge and discharge cycle is repeated 3 times. The discharge capacity Q of the battery is taken as the discharge capacity Q of the third cycle, in mAh.

[0159] The test results are shown in Table 2.

[0160] Table 2 The charging time of the batteries prepared in the various embodiments of this application is less than 19 minutes and the capacity is more than 190mAh. It can be seen that the batteries containing this application have both excellent fast charging performance and high capacity.

[0161] By comparing Examples 1-6, 8, 12, and 28 with Examples 7, 13-15, Example 9 with Examples 11 and 18, and Example 19 with Examples 20-22 and 32, it can be seen that when the values ​​of a and b meet the preferred range described in this application, it is more conducive to the balance between the fast charging performance and high capacity of the battery.

[0162] By comparing Examples 1-6, 8, 12, 28, Example 9 and Example 19, and Examples 7, 8, 13-15, Example 11, 18 and Examples 20-22, 32, it can be seen that when the battery satisfies 2≤a / b≤530, especially when it satisfies 2≤a / b≤98, it is more conducive to the balance between fast charging performance and capacity.

[0163] As shown in Comparative Examples 1-5, even if the values ​​of a and b are within appropriate ranges, when the value of a / b exceeds the range of 0.25 to 2700, the fast charging performance and / or capacity are poor, and a balance between fast charging performance and capacity cannot be achieved.

[0164] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this article and are not intended to limit the scope of protection of this article. Although this application has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of this article without departing from the essence and scope of the technical solutions of this article.

Claims

1. A positive electrode plate, characterized in that, The device includes a positive current collector and a positive electrode material layer disposed on at least one side of the positive current collector. The positive electrode material layer contains a positive electrode material, which includes a positive electrode active material. The positive electrode active material includes lithium nickel cobalt manganese oxide particles, which include an Fd3m phase. The lithium nickel cobalt manganese oxide particles also contain element M, and the bond energy between element M and O is greater than the bond energy between Ni and O. The positive electrode plate satisfies: 0.25≤a / b≤2700; Wherein, a% is the percentage of the Fd3m phase thickness to the diameter of the lithium nickel cobalt manganese oxide particles after the positive electrode plate has been cycled 200 times; b = b1 / b2, where b1 is the mass percentage of element M in the cathode material, and b2 is the mass percentage of element Ni in the cathode material based on the total mass of elements Ni, Co, and Mn.

2. The positive electrode sheet as described in claim 1, characterized in that, The positive electrode plate satisfies: 2≤a / b≤530.

3. The positive electrode sheet as described in claim 1, characterized in that, The range of a% is 0.01% to 4%; And / or, the range of b is 0.001 to 0.

06.

4. The positive electrode sheet as described in claim 3, characterized in that, The range of a% is 0.04% to 2%; And / or, the range of b is 0.003~0.03; And / or, the positive electrode plate satisfies: 2≤a / b≤98.

5. The positive electrode sheet as described in claim 1, characterized in that, The range of b2 is 50%~98%; And / or, the range of b1 is 0.05% to 4%.

6. The positive electrode sheet as described in claim 5, characterized in that, The range of b2 is 60%~95%; And / or, the range of b1 is 0.1% to 2%.

7. The positive electrode sheet as described in claim 1, characterized in that, In the lithium nickel cobalt manganese oxide particles, when the mass percentage of element Ni is ≥70% based on the total mass of Ni, Co and Mn elements, the range of b1 is 0.1%~4%.

8. The positive electrode sheet as described in claim 1, characterized in that, After the positive electrode is circulated for 200 cycles, the difference between the maximum thickness and the minimum thickness of the Fd3m phase is ≤16nm.

9. The positive electrode sheet as described in claim 1, characterized in that, The element M is selected from at least one of Zr, Ti, Si, Mo, B, Nb, Sb, Ta, Al, W, Sr, V, Y, Mg, and Ca.

10. The positive electrode sheet as described in claim 1, characterized in that, The surface of the lithium nickel cobalt manganese oxide particles is coated with a coating layer, and the coating layer material includes at least one of tungsten oxide, boron oxide, and aluminum oxide.

11. The positive electrode sheet as described in claim 1, characterized in that, The lithium nickel cobalt manganese oxide particles contain element M in the region from a depth of 1 / 3R to a depth of 2 / 3R from the surface, where R is the diameter of the lithium nickel cobalt manganese oxide particles.

12. The positive electrode sheet as described in claim 1, characterized in that, The cathode material is based on the total molar amount of elements Ni, Co and Mn, with the molar percentage of element Co ranging from 2% to 30%.

13. The positive electrode sheet as described in claim 1, characterized in that, The particle size Dv90 of the cathode material ranges from 4 to 15 μm, and the Dv10 ranges from 0.8 to 3 μm.

14. The positive electrode sheet as described in claim 1, characterized in that, The thickness of the positive electrode material layer is 60~180μm.

15. The positive electrode sheet as described in claim 1, characterized in that, The specific surface area of ​​the cathode material ranges from 0.2 to 1.5 m². 2 / g.

16. The positive electrode sheet as described in claim 1, characterized in that, The positive electrode active material also includes at least one of lithium iron phosphate and lithium manganese iron phosphate.

17. A battery, characterized in that, Includes the positive electrode sheet as described in any one of claims 1 to 16.

18. The battery as claimed in claim 17, characterized in that, It also includes an electrolyte, the viscosity of which is 1~10 mPa·s at 25°C.

19. The battery as claimed in claim 18, characterized in that, The electrolyte also contains solvents, including linear ester solvents and cyclic ester solvents; based on the total mass of the electrolyte, the mass percentage of linear ester solvents is 15% to 50%, and the mass percentage of cyclic ester solvents is 25% to 35%.

20. The battery as claimed in claim 17, characterized in that, The battery also includes a separator, the air permeability of which is in the range of 50~350s / 100mL.

21. The battery as claimed in claim 17, characterized in that, The battery also includes a negative electrode sheet; the areal density of the negative electrode sheet is 60~300 g / m³. 2 , And / or, the compaction density of the negative electrode sheet is 1.0~1.7 g / m³. 3 , And / or, the porosity of the negative electrode sheet is 10%~50%.

22. The battery as claimed in claim 21, characterized in that, The negative electrode sheet includes a negative electrode material, which includes a negative electrode active material, and the negative electrode active material includes at least one of graphite and silicon-based materials.

23. The battery as claimed in claim 22, characterized in that, The particle size Dv50 of the negative electrode material is 4~25μm.

24. The battery as claimed in claim 17, characterized in that, The battery includes a casing and a cell, and the casing is cylindrical or quadrangular prism-shaped.

25. The battery as claimed in claim 24, characterized in that, The casing is cylindrical, the ratio of the cell diameter to the casing diameter is ≥0.9, and the Fd3m phase thickness of the positive electrode sheet is 0.8~15nm after 200 cycles.

26. The battery as claimed in claim 24, characterized in that, The casing is cylindrical, and the battery includes tabs and a cell. The tabs include a positive tab and a negative tab, which are both led out from opposite ends along the axial direction of the cell. The range of b is 0.002~0.

06.

27. The battery as claimed in claim 24, characterized in that, The casing is cylindrical, and the battery includes tabs and a cell. The tabs include a positive tab and a negative tab, and both the positive tab and the negative tab are led out from the same end along the axial direction of the cell.

28. The battery as claimed in claim 24, characterized in that, The battery cell is a wound cell, and the wound cell includes a winding radius (R), where b ranges from 0.002 to 0.

06.

29. The battery as claimed in claim 17, characterized in that, The battery is a solid-state battery, and the value of b ranges from 0.0015 to 0.

06.

30. The battery as claimed in claim 29, characterized in that, The solid-state battery includes an electrolyte, which includes a sulfide solid-state electrolyte.

31. The battery as claimed in claim 17, characterized in that, The battery includes a casing, which includes at least one of an aluminum-plastic film and a metal casing.

32. An electrical appliance, characterized in that, Includes the battery as described in any one of claims 17 to 31.

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