Battery and electric device comprising same

Abstract

The invention relates to a battery and an electric device comprising the battery, and belongs to the technical field of batteries. The battery comprises a positive electrode current collector and a positive electrode material located on at least one surface of the positive electrode current collector, the positive electrode material comprises a positive electrode active material, and the positive electrode active material comprises olivine type phosphate and nickel cobalt lithium manganate. When a peak position difference a of a (131) crystal face in an XRD (X-Ray Diffraction) spectrogram of a positive plate under 80% SOC and 20% SOC of the battery, a mass content b of nickel cobalt lithium manganate in the positive electrode material and an intensity ratio c of a (003) diffraction peak to a (104) diffraction peak in the XRD spectrogram of the positive electrode material meet a (c / 1.2) * b which is more than or equal to 0.004 and less than or equal to 0.190, polarization of LMFP, lithium ion diffusion barrier of NCM and thermal stability balance of NCM can be realized; and the high-temperature performance of the battery, such as high-temperature cycle performance and high-temperature storage performance, is better.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular, to a battery and an electrical device including the battery. Background Art

[0002] Olivine-type phosphate contains Mn ions, and the material has a relatively high voltage plateau and good lithium-ion transmission performance. However, the ionic conductivity of olivine-type phosphate is poor, and it is prone to polarization during the charge and discharge cycle, resulting in serious dissolution of manganese ions, which deteriorates the performance of olivine-type phosphate batteries, especially the high-temperature performance. Summary of the Invention

[0003] An object of the present invention is to overcome the deficiencies of the above-mentioned prior art and provide a battery and an electrical device including the battery, so as to reduce the dissolution of Mn in olivine-type phosphate and enable the battery to have good high-temperature performance, such as high-temperature storage performance and high-temperature cycling performance.

[0004] To achieve the above object, in a first aspect, the present invention provides a battery, including a positive electrode sheet, the positive electrode sheet including a positive electrode current collector and a positive electrode material located on at least one surface of the positive electrode current collector, the positive electrode material including a positive electrode active material, the positive electrode active material including olivine-type phosphate and lithium nickel cobalt manganese oxide, and the battery satisfies:

[0005] 0.004 ≤ a (c / 1.2) ·b ≤ 0.190,

[0006] wherein, a = a2 - a1, a1 and a2 are the peak positions of the (131) crystal plane in the XRD patterns of the positive electrode sheet in the 20% SOC and 80% SOC states of the battery, in °;

[0007] b is the mass content of lithium nickel cobalt manganese oxide in the positive electrode material, dimensionless;

[0008] c is the intensity ratio of the (003) diffraction peak to the (104) diffraction peak in the XRD pattern of the positive electrode material, dimensionless.

[0009] In a second aspect, the present invention provides an electrical device including the battery.

[0010] Compared with the prior art, the beneficial effects of the present invention are as follows: By compounding olivine-type phosphate with a ternary cathode material and adjusting the peak position difference (a) of the (131) crystal plane in the XRD pattern of the cathode sheet at 80% SOC and 20% SOC states of the battery, the mass content (b) of lithium nickel cobalt manganate in the cathode material, and the intensity ratio (c) of the (003) diffraction peak to the (104) diffraction peak in the XRD pattern of the cathode material to satisfy a specific relational expression, the polarization of the olivine-type phosphate, the lithium ion diffusion barrier of NCM, and the thermal stability of NCM can be balanced, making the high-temperature performance of the battery, such as high-temperature cycling performance and high-temperature storage performance, better. Detailed Embodiments

[0011] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0012] In the present invention, among the technically characterized described in an open-ended manner, there are included closed technical solutions composed of the listed features, as well as open technical solutions containing the listed features.

[0013] In the present invention, regarding numerical ranges, unless otherwise specified, the above numerical ranges are considered continuous and include the minimum and maximum values of the range, as well as each value between such minimum and maximum values. Further, when the range refers to integers, it includes each integer between the minimum and maximum values of the range. In addition, when providing multiple range descriptions of features or characteristics, the ranges can be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all sub-ranges subsumed therein.

[0014] In the present invention, there is no particular limitation on the specific dispersion and stirring treatment methods.

[0015] The reagents or instruments used in the present invention that are not indicated by the manufacturer can all be conventional products obtained through commercial purchase.

[0016] Battery

[0017] The present invention provides a battery, including a cathode sheet, the cathode sheet including a cathode current collector and a cathode material located on at least one surface of the cathode current collector, the cathode material including a cathode active material, the cathode active material including olivine-type phosphate and lithium nickel cobalt manganate (NCM), and the battery satisfies:

[0018] 0.004 ≤ a (c / 1.2)·b ≤ 0.190,

[0019] wherein, a = a2 - a1, a1 and a2 are respectively the peak positions of the (131) crystal plane in the XRD patterns of the positive electrode sheet at 20% SOC and 80% SOC states of the battery, with the unit of °;

[0020] b is the mass content of lithium nickel cobalt manganese oxide in the positive electrode material, dimensionless;

[0021] c is the intensity ratio of the (003) diffraction peak to the (104) diffraction peak in the XRD pattern of the positive electrode material, dimensionless.

[0022] When NCM is doped into olivine-type phosphate, the characteristics of high ionic conductivity of NCM can be utilized to improve the overall ionic migration rate of the material, make the lithium intercalation / deintercalation of olivine-type phosphate smoother at each voltage platform, and at the same time improve the uniformity of lithium intercalation / deintercalation inside the olivine-type phosphate material, reduce the stress during lithium intercalation / deintercalation of olivine-type phosphate, inhibit the polarization of olivine-type phosphate, reduce the risk of Mn element dissolution in olivine-type phosphate, which is beneficial to improving the high-temperature performance of the battery, such as high-temperature storage and cycling performance; in addition, due to the role of Mn contained in NCM, its structural stability is good, ensuring that it can stably play an inhibitory role on the polarization of olivine-type phosphate during charge-discharge cycles.

[0023] (131) crystal plane diffraction peak is the characteristic peak of olivine-type phosphate, and the peak position represents the crystal plane spacing. The inventors found that when the structure of olivine-type phosphate is unstable, the peak position of the (131) crystal plane in the XRD patterns of the positive electrode sheet at different battery SOC states will change, especially at 80% SOC and 20% SOC states of the battery. The peak position difference (a) of the (131) crystal plane in the XRD patterns of the positive electrode sheet at 80% SOC and 20% SOC states of the battery can reflect the structural stability of olivine-type phosphate. The smaller its value, the smaller the structural change of olivine-type phosphate with charge-discharge, and the better the structural stability. However, if the structural stability of olivine-type phosphate is too strong and the crystallinity is relatively high, it is not conducive to the exertion of its capacity.

[0024] The value of the peak position difference (a) of the (131) crystal plane in the XRD patterns of the positive electrode sheet at 80% SOC and 20% SOC states of the battery can be adjusted by adjusting the type of carbon source in the carbon-coated material of olivine-type phosphate, the calcination temperature, holding time and heating rate during the carbon coating process, the type of doping elements in olivine-type phosphate, etc.

[0025] The present invention does not limit the detection method of the peak position difference (a) of the (131) crystal plane in the XRD pattern of the positive electrode sheet at the 80% SOC and 20% SOC states of the battery. Those skilled in the art can detect the peak position difference (a) of the (131) crystal plane in the XRD pattern of the positive electrode sheet at the 80% SOC and 20% SOC states of the battery according to conventional technical means. Exemplarily, the peak position difference (a) of the (131) crystal plane in the XRD pattern of the positive electrode sheet at the 80% SOC and 20% SOC states of the battery can be detected by the following method:

[0026] Discharge the battery at 0.33C to 2.5V, then charge the battery at 0.33C to 4.25V, discharge the battery at 0.33C to 2.5V, record the discharged capacity as C1, adjust the charge to 0.2 times of C1 state by charging at 0.33C, denoted as 20% SOC, disassemble the battery to obtain the positive electrode sheet in an inert atmosphere, perform XRD test on the obtained positive electrode sheet, and record the peak position angle corresponding to the (131) crystal plane, i.e., a1;

[0027] Discharge the battery at 0.33C to 2.5V, then charge the battery at 0.33C to 4.25V, discharge the battery at 0.33C to 2.5V, record the discharged capacity as C1, adjust the charge to 0.8 times of C1 state by charging at 0.33C, denoted as 80% SOC, disassemble the battery to obtain the positive electrode sheet in an inert atmosphere, perform XRD test on the obtained positive electrode sheet, and record the peak position angle corresponding to the (131) crystal plane, i.e., a2;

[0028] Then calculate the peak position difference (a) of the (131) crystal plane in the XRD pattern of the positive electrode sheet at the 80% SOC and 20% SOC states of the battery;

[0029] Among them, the specific test conditions for the XRD test are as follows: Cu target, the scanning voltage is 40KV, the current is 40mA, the scanning range is 5 - 80°, the scanning speed is 5° / min, the XRD is calibrated by the silicon internal standard method, and the XRD instrument used can be Ultima IV of Rigaku, Japan;

[0030] In the XRD pattern, the diffraction peak at the position where the diffraction angle 2θ is 35.5 ± 0.5° is the diffraction peak of the (131) crystal plane.

[0031] The mass content (b) of lithium nickel cobalt manganate in the positive electrode material represents the addition amount of NCM in the positive electrode material. The larger its value, the more the addition amount of NCM in the positive electrode material. When the addition amount of NCM in the positive electrode material is too small, the inhibitory effect of NCM on the polarization of olivine phosphate is not obvious; when the addition amount of NCM in the positive electrode material is too large, it will lead to a decrease in the thermal stability of the entire material system, which is instead not conducive to the high-temperature performance.

[0032] The value of the mass content (b) of lithium nickel cobalt manganese oxide in the cathode material can be adjusted by controlling the mass ratio of olivine phosphate to NCM, the proportion of the cathode active material in the cathode material, etc.

[0033] Regarding the detection method of the mass content (b) of lithium nickel cobalt manganese oxide in the cathode material, the present invention does not make any limitations. Those skilled in the art can detect the mass content (b) of lithium nickel cobalt manganese oxide in the cathode material according to conventional technical means. Exemplarily, the mass content (b) of lithium nickel cobalt manganese oxide in the cathode material can be measured by an inductively coupled plasma (ICP) detection method. For example:

[0034] Discharge the battery at 0.33C to 2.5V, disassemble the cathode plate, then soak it in dimethyl carbonate (DMC), dry it, scrape off the cathode material on the cathode plate for energy dispersive spectrometer (EDS) test. At a magnification of 15k, observe the morphology and size of the material, and test the element types and their contents (normalized atomic percentage content) of particles with different external dimensions in the field of view in the EDS point-scanning signal acquisition mode. Select at least 3 locations of similar particles for testing to obtain accurate parallel sample test results. Identify the material type based on this data, and at the same time obtain the average molar ratio of various transition metal elements to the total transition metal elements, which is the chemical composition of each component of the cathode main material in the electrode plate. Subsequently, perform ICP detection on this sample (accurately weigh 0.5g of the scraped cathode material powder, disperse it in 20mL of water, then add 10mL of nitric acid (the mass percentage content of HNO3 is 66%), disperse and heat it until the cathode material powder is completely dissolved, and make the volume up to 100mL with water to obtain the test solution to be measured; perform ICP test on the test solution to be measured, and set the working conditions of the ICP instrument as follows: gas flow rate 0.5L / min, power 1150W, and perform ICP test), confirm the concentration of the corresponding chemical composition elements of the cathode active material (that is, the specific molar ratio of chemical elements); confirm the molar ratio of various transition metals to the total metals in the electrode plate, combine the actual metal molar ratios of various materials confirmed by the above EDS, calculate the mass ratio θ of the cathode material with specific metal elements to all materials as θ = ICP molar ratio / EDS molar ratio, and the mass ratio of the remaining other types of materials is 1 - θ. Determine the mass ratio of the two cathode active materials according to the chemical composition, and at the same time confirm the mass content of each element in the single olivine phosphate and lithium nickel cobalt manganese oxide by the above means.

[0035] In the XRD pattern of the cathode material, the intensity ratio (c) of the (003) diffraction peak to the (104) diffraction peak represents the degree of disorder of the NCM crystal structure. If its value is too large, it indicates that the degree of disorder of the NCM crystal structure is too large, which will lead to poor cycling performance and thermal stability of the NCM material; if its value is too small, it means that the NCM crystal structure is too ordered, thus increasing the diffusion barrier of lithium ions and affecting the internal resistance of the material.

[0036] The value of the intensity ratio (c) of the (003) diffraction peak to the (104) diffraction peak in the XRD pattern of the cathode material can be regulated by adjusting the content of manganese element in lithium nickel cobalt manganate, the preparation process parameters of lithium nickel cobalt manganate material (such as calcination temperature, holding time, heating rate), the particle size of lithium nickel cobalt manganate, etc.

[0037] Regarding the detection method of the intensity ratio (c) of the (003) diffraction peak to the (104) diffraction peak in the XRD pattern of the cathode material, the present invention does not make any limitation, and those skilled in the art can detect the intensity ratio (c) of the (003) diffraction peak to the (104) diffraction peak in the XRD pattern of the cathode material according to conventional technical means. Exemplarily, the intensity ratio (c) of the (003) diffraction peak to the (104) diffraction peak in the XRD pattern of the cathode material can be detected by the following method:

[0038] Discharge the battery to 2.5V at 0.33C, disassemble the cathode plate, soak the cathode plate in DMC at room temperature for 60 min, take it out, dry it, scrape off the cathode material on the surface of the current collector, perform XRD test on the obtained cathode material, record the intensities of the diffraction peaks corresponding to the (003) crystal plane and the (104) crystal plane, namely I(003) and I(104), and then calculate the intensity ratio (c) of the (003) diffraction peak to the (104) diffraction peak in the XRD pattern of the cathode material;

[0039] Among them, the specific test conditions for the XRD test are: Cu target, the scanning voltage is 40KV, the current is 40mA, the scanning range is 5 - 80°, the scanning speed is 2° / min, the XRD is calibrated by the silicon internal standard method, and the XRD instrument used can be Ultima IV of Rigaku, Japan;

[0040] In the XRD pattern, the diffraction peak at the position where the diffraction angle 2θ is 18.5 ± 0.3° is the diffraction peak of the (003) crystal plane, and the diffraction peak at the position where the diffraction angle 2θ is 44.5 ± 0.3° is the diffraction peak of the (104) crystal plane.

[0041] In the XRD spectra of the positive electrode sheet at 80% SOC and 20% SOC of the battery, the peak position difference (a) of the (131) crystal plane, the mass content (b) of lithium nickel cobalt manganate in the positive electrode material, and the intensity ratio (c) of the (003) diffraction peak to the (104) diffraction peak in the XRD spectrum of the positive electrode material all affect the high-temperature performance of the battery to varying degrees, such as high-temperature cycling performance and high-temperature storage performance. It is difficult to achieve good high-temperature performance of the battery by controlling a single variable, such as having both good high-temperature cycling performance and high-temperature storage performance. In the present invention, by compounding olivine-type phosphate with NCM and adjusting the peak position difference (a) of the (131) crystal plane in the XRD spectra of the positive electrode sheet at 80% SOC and 20% SOC of the battery, the mass content (b) of lithium nickel cobalt manganate in the positive electrode material, and the intensity ratio (c) of the (003) diffraction peak to the (104) diffraction peak in the XRD spectrum of the positive electrode material to satisfy the above specific relationship, the polarization and capacity utilization of the olivine-type phosphate, the lithium-ion diffusion barrier of NCM, and the thermal stability of NCM are balanced, making the high-temperature performance of the battery, such as high-temperature cycling performance and high-temperature storage performance, better. The (c / 1.2) power of a is involved in the above relationship, and this power relationship indicates a non-linear coupling relationship between a and c, reflecting the adjustment effect of the NCM crystal structure characteristics on the change of the lattice parameters of the olivine-type phosphate, and further illustrating the comprehensive influence of the interaction between the crystal structure characteristics and the change of the lattice parameters on the high-temperature performance of the battery.

[0042] Exemplarily, the value of a (c / 1.2) ·b can be selected as 0.004, 0.006, 0.008, 0.010, 0.015, 0.020, 0.025, 0.030, 0.035, 0.040, 0.045, 0.050, 0.055, 0.060, 0.065, 0.070, 0.075, 0.080, 0.085, 0.090, 0.095, 0.100, 0.110, 0.120, 0.130, 0.140, 0.150, 0.160, 0.170, 0.180, 0.190, or the range formed by any two of the above values.

[0043] In one preferred embodiment, the battery satisfies: 0.008 ≤ a (c / 1.2) ·b ≤ 0.036. By controlling the value of a (c / 1.2) ·b within this specific range, the polarization and capacity utilization of the olivine-type phosphate, the lithium-ion diffusion barrier of NCM, and the thermal stability of NCM can be better balanced, further improving the high-temperature performance of the battery, such as high-temperature cycling performance and high-temperature storage performance.

[0044] In some of these embodiments, the range of the peak position difference (a) of the (131) crystal plane in the XRD pattern of the positive electrode sheet at the 80% SOC and 20% SOC states of the battery is 0.05° to 0.20°, such as 0.05°, 0.07°, 0.10°, 0.12°, 0.15°, 0.18°, 0.20°, or the range formed by any two of the above values.

[0045] In one preferred embodiment, the range of the peak position difference (a) of the (131) crystal plane in the XRD pattern of the positive electrode sheet at the 80% SOC and 20% SOC states of the battery is 0.10° to 0.15°.

[0046] When the peak position difference (a) of the (131) crystal plane in the XRD pattern of the positive electrode sheet at the 80% SOC and 20% SOC states of the battery is in the range of 0.05° to 0.20°, especially in the range of 0.10° to 0.15°, the stability of the olivine-type phosphate is more suitable, and the performance of the battery such as high-temperature storage and cycling is better.

[0047] In some of these embodiments, the range of the mass content (b) of the lithium nickel cobalt manganese oxide in the positive electrode material is 0.01 to 0.5, such as 0.01, 0.03, 0.05, 0.07, 0.09, 0.10, 0.20, 0.30, 0.40, 0.50, or the range formed by any two of the above values.

[0048] In one preferred embodiment, the range of the mass content (b) of the lithium nickel cobalt manganese oxide in the positive electrode material is 0.05 to 0.20.

[0049] When the mass content (b) of the lithium nickel cobalt manganese oxide in the positive electrode material is in the range of 0.01 to 0.50, especially in the range of 0.05 to 0.20, it is more beneficial to balance the polarization of the olivine-type phosphate and the thermal stability of the positive electrode material, and the high-temperature performance of the battery such as high-temperature cycling performance and high-temperature storage performance is better.

[0050] In some of these embodiments, the range of the intensity ratio (c) of the (003) diffraction peak to the (104) diffraction peak in the XRD pattern of the positive electrode material is 0.5 to 1.8, such as 0.5, 0.7, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, or the range formed by any two of the above values.

[0051] In one preferred embodiment, the range of the intensity ratio (c) of the (003) diffraction peak to the (104) diffraction peak in the XRD pattern of the positive electrode material is 1.0 to 1.5.

[0052] When the intensity ratio (c) of the (003) diffraction peak to the (104) diffraction peak in the XRD pattern of the positive electrode material is in the range of 0.5 to 1.8, especially in the range of 1.0 to 1.5, the degree of disorder of NCM is more suitable, the cycling and thermal stability performance is good, the diffusion barrier of lithium ions is lower, and the high-temperature performance of the battery such as high-temperature cycling performance and high-temperature storage performance is better.

[0053] In some of these embodiments, the range of a1 is 35.0 to 35.9, such as 35.0, 35.1, 35.2, 35.3, 35.4, 35.5, 35.6, 35.7, 35.8, 35.9 or the range formed by any two of the above values. The magnitude of the a1 value reflects the content of Mn in the olivine-type phosphate. Controlling the value of a1 within the above suitable range not only benefits the improvement of the energy density of the battery, but also makes Mn more stable in the lithium manganese iron phosphate structure.

[0054] In some of these embodiments, the range of a2 is 35.2 to 36.0, such as 35.2, 35.3, 35.4, 35.5, 35.6, 35.7, 35.8, 35.9, 36.0 or the range formed by any two of the above values, so as to reduce the risk of Mn dissolution in the olivine-type phosphate.

[0055] In some of these embodiments, the general structural formula of the lithium nickel cobalt manganese oxide is: LiNi x Co y Mn z M (1-x-y-z) O2, where 0 < x < 1, 0 < y < 1, 0 < z < 1, 0 ≤ 1 - x - y - z < 1, and the range of x / y is 4.5 to 7; M is a doping element selected from at least one of Al, W, Mg, Sr, and Zr. Among them, x can be selected from 0.55, 0.60, 0.65, 0.70, 0.75, 0.80, 0.85, 0.87 or the range formed by any two of the above values; y can be selected from 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.12, 0.14, 0.15 or the range formed by any two of the above values; z can be selected from 0.10, 0.15, 0.20, 0.25, 0.30, 0.35, 0.40 or the range formed by any two of the above values. In one embodiment, the range of x / y is 4.5 to 7, such as 4.5, 5, 5.5, 6, 6.5, 7 or the range formed by any two of the above values, which not only enables the lithium nickel cobalt manganese oxide to maintain a good layered structure, but also reduces the degree of disorder of the lithium nickel cobalt manganese oxide.

[0056] The lithium nickel cobalt manganese oxide may or may not contain a coating material. When a coating material is present, it may cover part or all of the surface of the lithium nickel cobalt manganese oxide. The present invention does not limit the type of the coating material in the lithium nickel cobalt manganese oxide. For example, the coating material contains at least one element selected from the following: aluminum (Al), titanium (Ti), tungsten (W), boron (B), phosphorus (P), cobalt (Co), yttrium (Y), and silicon (Si). Meanwhile, the present invention also does not limit the content of the coating material in the lithium nickel cobalt manganese oxide. Exemplarily, the content of the coating material in the lithium nickel cobalt manganese oxide is 500 - 5000 ppm, such as 500 ppm, 1000 ppm, 1500 ppm, 2000 ppm, 2500 ppm, 3000 ppm, 4000 ppm, 4500 ppm, 5000 ppm, or an interval range formed by any two of the above values.

[0057] In some embodiments, the Dv50 particle size of the lithium nickel cobalt manganese oxide is 2.5 - 4.5 μm, such as 2.5 μm, 3.0 μm, 3.5 μm, 4.0 μm, 4.5 μm, or an interval range formed by any two of the above values.

[0058] The present invention does not limit the method for detecting the Dv50 particle size of the lithium nickel cobalt manganese oxide. Those skilled in the art can detect the Dv50 particle size of the lithium nickel cobalt manganese oxide according to conventional technical means. Exemplarily, the method for testing the Dv50 particle size of the lithium nickel cobalt manganese oxide is as follows:

[0059] Take a discharged battery, disassemble it to obtain the positive electrode sheet, dry the positive electrode sheet, collect 0.1 - 0.2 g of the positive electrode material powder with a scraper, take a photograph of the positive electrode material powder in the SEM image of the obtained positive electrode material powder with a scanning electron microscope (SEM), measure the size of the lithium nickel cobalt manganese oxide in the positive electrode material powder in the SEM image by using the MEARSURE NANO software, collect the particle size of the lithium nickel cobalt manganese oxide by using the diagonal line scribing method. After the sample size reaches more than 100, count the particle size distribution and calculate the particle size - related parameter of the lithium nickel cobalt manganese oxide: Dv50.

[0060] In the present invention, the preparation method of the lithium nickel cobalt manganese oxide is not limited. Those skilled in the art can prepare the lithium nickel cobalt manganese oxide according to conventional technical means. Exemplarily, the preparation method of the lithium nickel cobalt manganese oxide includes the following steps:

[0061] Mix the lithium nickel cobalt manganese oxide precursor and the lithium source and then sinter them to obtain the lithium nickel cobalt manganese oxide.

[0062] The lithium nickel cobalt manganese oxide precursor contains Ni, Co, and Mn in a target stoichiometric ratio (i.e., the ratio of these three elements in the lithium nickel cobalt manganese oxide precursor is the same as the ratio of these three elements in the obtained lithium nickel cobalt manganese oxide, and the same applies to other similar expressions). The lithium nickel cobalt manganese oxide precursor is one or more of oxides, hydroxides, and carbonates of Ni, Co, and Mn. For example, the lithium nickel cobalt manganese oxide precursor is a hydroxide of Ni, Co, and Mn.

[0063] The lithium nickel cobalt manganese oxide precursor can be obtained by methods known in the art, such as by coprecipitation, gel method, or solid-phase method. As an example, the preparation method of the lithium nickel cobalt manganese oxide precursor includes the following steps:

[0064] Disperse the Ni source, Co source, and Mn source in a solvent to obtain a mixed solution;

[0065] Pump the obtained mixed solution, strong base solution, and complexing agent solution into a stirred reaction kettle at the same time, control the pH value of the reaction solution to be 10-13, and the temperature in the reaction kettle to be 25°C-90°C. During the reaction process, protect with an inert atmosphere gas (such as at least one of nitrogen and inert gas); after the reaction is completed, aging, filtration, washing, and vacuum drying are carried out to obtain a hydroxide containing Ni, Co, and Mn, that is, the lithium nickel cobalt manganese oxide precursor is obtained.

[0066] During the preparation of the lithium nickel cobalt manganese oxide precursor, the Ni source used includes but is not limited to at least one of nickel sulfate, nickel nitrate, nickel chloride, nickel oxalate, and nickel acetate;

[0067] and / or, the Co source used includes but is not limited to at least one of cobalt sulfate, cobalt nitrate, cobalt chloride, cobalt oxalate, and cobalt acetate;

[0068] and / or, the Mn source used includes but is not limited to at least one of manganese sulfate, manganese nitrate, manganese chloride, manganese oxalate, and manganese acetate;

[0069] and / or, the base in the strong base solution used includes but is not limited to at least one of sodium hydroxide and potassium hydroxide;

[0070] and / or, the complexing agent solution used includes but is not limited to ammonia water.

[0071] During the preparation of the lithium nickel cobalt manganese oxide precursor, the amounts of the Ni source, Co source, and Mn source used can be selected to satisfy: molar amount of Ni element: molar amount of Co element: molar amount of Mn element = (0.55-0.95):(0.03-0.15):(0.1-0.4).

[0072] In the process of preparing the lithium nickel cobalt manganese oxide, the Li 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).

[0073] In the process of preparing the lithium nickel cobalt manganese oxide, the dosage ratio of the lithium source used to the ternary material precursor used satisfies: molar amount of Li element: sum of molar amounts of Ni, Co, and Mn elements = (1 - 1.05):1.

[0074] When mixing the lithium nickel cobalt manganese oxide precursor and the lithium source, mixing can be carried out in a ball mill or a high-speed mixer.

[0075] In the process of preparing the lithium nickel cobalt manganese oxide from the lithium nickel cobalt manganese oxide precursor, the sintering atmosphere is an inert atmosphere, such as a nitrogen atmosphere, a helium atmosphere, or an argon atmosphere.

[0076] In the process of preparing the lithium nickel cobalt manganese oxide from the lithium nickel cobalt manganese oxide precursor, the sintering temperature can be selected as 700 - 1000 °C, and the sintering time can be selected as 6 - 9 h.

[0077] In addition, when preparing the lithium nickel cobalt manganese oxide precursor, a certain amount of doping element source (if any) can also be dispersed in a solvent together with the Ni source, Co source, and Mn source as needed to prepare the lithium nickel cobalt manganese oxide precursor. The doping element source is selected from at least one of an Al source, a W source, an Mg source, an Sr source, a Zr source, etc., to obtain a lithium nickel cobalt manganese oxide containing a certain amount of doping elements.

[0078] When preparing the lithium nickel cobalt manganese oxide, coating treatment can also be carried out on the lithium nickel cobalt manganese oxide as needed. Specifically, the coating material is coated on the surface of the lithium nickel cobalt manganese oxide by dry coating (high-temperature solid-phase method), and the surface of the lithium nickel cobalt manganese oxide is partially or completely coated with a coating layer formed by the coating material. Exemplarily, the coating layer contains at least one element selected from the following (hereinafter referred to as "coating element"): aluminum (Al), phosphorus (P), silicon (Si), titanium (Ti), tungsten (W), boron (B), cobalt (Co), or yttrium (Y).

[0079] In some embodiments, the olivine-type phosphate includes at least one of lithium iron manganese phosphate and doped lithium iron manganese phosphate.

[0080] In some embodiments, the molar content of manganese element in the olivine-type phosphate accounts for 60% - 85% of the total transition metal elements, such as 60%, 65%, 70%, 75%, 80%, 85%, or the range formed by any two of the above values.

[0081] In some of these embodiments, the average primary particle size of the olivine-type phosphate ranges from 80 to 200 nm, such as 80 nm, 100 nm, 120 nm, 140 nm, 160 nm, 180 nm, 200 nm, or the range formed by any two of the above values.

[0082] It should be noted that the average primary particle size of the olivine-type phosphate in the positive electrode active material of the present application can be confirmed by the following method: disassemble the positive electrode plate from the battery, then soak it in dimethyl carbonate (DMC), dry it, scrape off the positive electrode material on the positive electrode plate for EDS energy spectrum test, identify the olivine-type phosphate and layered lithium nickel cobalt manganate particles by point scanning in a magnified view, obtain the particle morphology of the olivine-type phosphate in three regions under a scanning electron microscope with a magnification of 30k, measure the diagonal length of the primary particles of the olivine-type phosphate through nanomeasurer software, test 80 samples, and count the results of the three regions, which is the average primary particle size of the olivine-type phosphate.

[0083] In some of these embodiments, the chemical formula of lithium manganese iron phosphate is LiMn d Fe 1-d PO4, where 0 < d < 1. d can be selected as 0.5, 0.6, 0.7, 0.8, 0.9, 0.95, 0.99, or the range formed by any two of the above values. The lithium manganese iron phosphate can either contain no doping elements or contain doping elements. The present invention does not limit the type of doping elements in the lithium manganese iron phosphate. For example, the doping elements include but are not limited to at least one of V, W, Ti, and Mg; at the same time, the present invention does not limit the content of the doping elements in the lithium manganese iron phosphate. Exemplarily, the content of the doping elements in the lithium manganese iron phosphate is 500 - 2000 ppm. The lithium manganese iron phosphate can either contain no coating material or be coated with a coating material on some or all of its surfaces. The present invention does not limit the type of the coating material in the lithium manganese iron phosphate. For example, the coating material includes at least one of graphene and carbon nanotubes; at the same time, the present invention does not limit the content of the coating material in the lithium manganese iron phosphate. Exemplarily, the content of the coating material in the lithium manganese iron phosphate is 1.5 - 2.5 wt%, such as 1.5 wt%, 1.8 wt%, 2 wt%, 2.2 wt%, 2.5 wt%, or the range formed by any two of the above values.

[0084] In the present invention, the preparation method of the olivine-type phosphate is not limited, and those skilled in the art can prepare the olivine-type phosphate according to conventional technical means. Exemplarily, the preparation method of the olivine-type phosphate includes the following steps:

[0085] Mix a manganese source, an iron source, a phosphorus source, a lithium source and a solvent, and react at 140 - 160 °C for 8 - 12 h to obtain an olivine-type phosphate precursor;

[0086] Disperse the obtained olivine-type phosphate precursor and a carbon source in a solvent. After spray-drying the obtained mixture, perform a calcination treatment under a protective atmosphere to obtain an olivine-type phosphate.

[0087] Exemplarily, in the process of preparing the olivine-type phosphate, the manganese source used includes but is not limited to at least one of manganese tetroxide, manganese nitrate, manganese carbonate, manganese oxalate, manganese sulfate, manganese chloride, and manganese acetate.

[0088] Exemplarily, the iron source used includes but is not limited to at least one of ferrous sulfate, iron phosphate, ferrous phosphate, iron hydroxide, ferrous hydroxide, iron carbonate, ferrous carbonate, iron acetate, ferrous acetate, iron(III) oxide, manganese tetroxide, ferrous oxalate, and iron oxalate.

[0089] Exemplarily, the phosphorus source used includes but is not limited to at least one of phosphoric acid, lithium dihydrogen phosphate, lithium phosphate, diammonium hydrogen phosphate, and ammonium phosphate.

[0090] Exemplarily, the lithium source used includes but is not limited to at least one of lithium hydroxide, lithium dihydrogen phosphate, lithium phosphate, lithium carbonate, lithium nitrate, lithium oxalate, lithium citrate, and lithium acetate.

[0091] Exemplarily, the solvent used includes but is not limited to water.

[0092] Exemplarily, the carbon source used includes but is not limited to at least one of glucose (GLC), sucrose, polyethylene glycol (PEG), and polyvinyl alcohol. Exemplarily, in the process of preparing the lithium iron manganese phosphate precursor, the molar ratio of the manganese source, the iron source, and the phosphorus source used is (0.6 - 0.85):(0.15 - 0.4):(1.02 - 1.05).

[0093] Exemplarily, the protective atmosphere is an inert atmosphere, such as a nitrogen atmosphere.

[0094] Exemplarily, the calcination temperature can be selected as 550 - 680 °C, such as 550 °C, 600 °C, 650 °C, 680 °C, or the range formed by any two of the above values.

[0095] Exemplarily, the calcination time is 4 - 10 h, such as 6 h, or the range formed by any two of the above values.

[0096] In the process of preparing the olivine-type phosphate, a doping element raw material can also be used. For example, when the olivine-type phosphate precursor and a carbon source are dispersed in a solvent, a doping element raw material can also be added and dispersed together, and then spray-dried and calcined under a protective atmosphere to obtain the olivine-type phosphate. Exemplarily, the doping element raw material includes but is not limited to at least one of a V source, a W source, a Ti source, and a Mg source.

[0097] In some embodiments, the mass content of the olivine-type phosphate in the cathode material ranges from 0.46 to 0.95, such as 0.46, 0.50, 0.55, 0.60, 0.65, 0.70, 0.75, 0.80, 0.85, 0.90, 0.95, or the range formed by any two of the above values.

[0098] In some embodiments, the mass content of the cathode active material in the cathode material is 0.95 to 0.985, such as 0.950, 0.965, 0.970, 0.980, 0.985, or the range formed by any two of the above values.

[0099] In addition to the above cathode active material, the cathode material further includes a cathode conductive agent and a cathode binder.

[0100] The cathode conductive agent is used to provide conductivity, and any conductive agent can be used without particular limitation as long as it has suitable electron conductivity and does not significantly cause adverse chemical changes in the battery. Exemplarily, the cathode conductive agent includes but is not limited to at least one of carbon nanotubes, carbon black, graphite, carbon fiber, activated carbon, mesoporous carbon, fullerenes, etc., where the carbon fiber is, for example, carbon nanofiber, etc.; the carbon black is, for example, SP (Super P, the same below), acetylene black, Ketjen black, etc.

[0101] In some embodiments, the mass content of the cathode conductive agent in the cathode material is 0.01 to 0.04, such as 0.010, 0.015, 0.020, 0.025, 0.030, 0.035, 0.040, or the range formed by any two of the above values.

[0102] The cathode binder is used to improve the adhesion between the cathode active material particles and the adhesion between the cathode active material and the cathode current collector, and any binder can be used without particular limitation as long as it has suitable binder properties and does not significantly cause adverse chemical changes in the battery. Exemplarily, the cathode binder includes but is not limited to fluorinated polyolefin-based binders, and the fluorinated polyolefin-based binders include but are not limited to polyvinylidene fluoride (PVDF), vinylidene fluoride copolymers, or their modified (e.g., modified with carboxylic acid, acrylic acid, acrylonitrile, etc.) derivatives, etc.

[0103] In some of these embodiments, the mass content of the positive electrode binder in the positive electrode material is 0.01 to 0.04, such as 0.010, 0.015, 0.020, 0.025, 0.030, 0.035, 0.040, or the range formed by any two of the above values.

[0104] The positive electrode material can be located on one side of the positive electrode current collector or on both sides of the positive electrode current collector.

[0105] The present invention places no particular limitation on the positive electrode current collector, as long as it has conductivity and will not cause adverse chemical changes in the battery, and for example, aluminum, nickel, titanium, stainless steel, fired carbon can be used; or aluminum or stainless steel surface-treated with one of carbon, nickel, titanium, silver, etc.

[0106] The positive electrode sheet of the present invention can be prepared according to conventional methods in the art. For example, the positive electrode active material, the positive electrode conductive agent, and the positive electrode 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 processes such as drying, rolling, and slitting, a positive electrode sheet is obtained. Among them, the solvents used for preparing the positive electrode slurry include but are not limited to at least one of N-methylpyrrolidone (NMP) and deionized water.

[0107] Battery

[0108] The present invention also provides a battery, including the positive electrode sheet, the negative electrode sheet, and the electrolyte.

[0109] The negative electrode sheet of the present invention includes a negative electrode current collector and a positive electrode material located on at least one surface of the negative electrode current collector, and the negative electrode material contains a negative electrode active material.

[0110] The present invention places no particular limitation on the negative electrode active material. Exemplarily, the negative electrode active material includes but is not limited to natural graphite, artificial graphite, mesophase microbeads (MCMB), hard carbon, soft carbon, silicon, SiO f (0 < f < 2, such as f = 1), silicon carbide, Li4Ti5O 12 and at least one of them.

[0111] In some of these embodiments, the negative electrode active material includes graphite, and the average particle diameter of the graphite is 8 to 13 μm, such as 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, or the range formed by any two of the above values.

[0112] The present invention places no limitation on the detection method of the average particle diameter of the graphite. Those skilled in the art can detect the average particle diameter of the graphite according to conventional technical means. Exemplarily, the test method for the average particle diameter of the graphite is as follows:

[0113] The secondary battery in an empty state is disassembled, and after scraping the powder from the obtained negative electrode sheet, it is tested with reference to the D50 test method in GB / T 24533-2019.

[0114] In some embodiments, the mass content of the negative electrode active material in the negative electrode material is 0.93 to 0.98, such as 0.93, 0.95, 0.97, 0.98 or the range formed by any two of the above values.

[0115] The negative electrode active material layer may further include a negative electrode conductive agent and / or a negative electrode binder.

[0116] The negative electrode conductive agent is used to provide conductivity, and any conductive agent can be used without particular limitation as long as it has suitable electron conductivity and does not significantly cause adverse chemical changes in the battery. Exemplarily, the negative electrode conductive agent includes but is not limited to at least one of carbon nanotubes, carbon black, graphite, carbon fiber, activated carbon, mesoporous carbon, fullerenes, etc., where carbon fiber such as carbon nanofiber, etc.; carbon black such as SP, acetylene black, Ketjen black, etc.

[0117] In some embodiments, the mass content of the negative electrode conductive agent in the negative electrode material is 0.01 to 0.05, such as 0.010, 0.015, 0.020, 0.025, 0.030, 0.035, 0.040, 0.045, 0.050 or the range formed by any two of the above values.

[0118] The negative electrode binder is used to improve the adhesion between 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 binder properties and does not significantly cause adverse chemical changes in the battery. Exemplarily, the negative electrode binder includes but is not limited to fluorinated polyolefin binders, and fluorinated polyolefin binders include but are not limited to polyvinylidene fluoride (PVDF), vinylidene fluoride copolymers or their modified (e.g., carboxylic acid, acrylic acid, acrylonitrile, etc. modified) derivatives, etc.

[0119] In some embodiments, the mass content of the negative electrode binder in the negative electrode material is 0.01 to 0.05, such as 0.010, 0.015, 0.020, 0.025, 0.030, 0.035, 0.040, 0.045, 0.050 or the range formed by any two of the above values.

[0120] The negative electrode material can be located on one side of the positive electrode current collector or on both sides of the negative electrode current collector.

[0121] The present invention imposes no particular limitation on the negative electrode current collector, as long as it has electrical conductivity and does not cause adverse chemical changes in the battery, and for example, copper, stainless steel, aluminum, nickel, titanium, fired carbon, copper or stainless steel surface-treated with at least one of carbon, nickel, titanium, silver, etc., or an aluminum-cadmium alloy can be used.

[0122] The electrolyte of the present invention can select various electrolytes applicable to batteries in the art. The electrolyte includes an electrolyte and a solvent, and the electrolyte usually includes a lithium salt.

[0123] Exemplarily, the lithium salt includes but is not limited to at least one of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorooxalate borate (LiDFOB), lithium bis(oxalato)borate (LiBOB), lithium difluorophosphate (LiPO2F2), lithium difluoro bis(oxalato)phosphate (LiDFOP), lithium tetrafluorooxalate phosphate (LiTFOP). The concentration of the electrolyte in the electrolyte can be selected to be 0.9 - 2.0 mol / L.

[0124] Exemplarily, the solvent includes but is not limited to at least one of ethylene carbonate (EC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), propylene carbonate (PC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate (BC), fluoroethylene carbonate (FEC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), ethyl methyl sulfone (EMS), diethyl sulfone (ESE). The mass content of the solvent in the electrolyte can be selected to be 0.55 - 0.92.

[0125] In addition, the electrolyte can also contain additives. Exemplarily, the additives can include negative electrode film-forming additives, can also include positive electrode film-forming additives, and can also include additives that can improve certain battery performances, such as additives for improving the high-temperature performance of the battery, additives for improving the overcharge performance of the battery, additives for improving the low-temperature performance of the battery, etc.

[0126] The battery may further include a separator located between the positive electrode sheet and the negative electrode sheet for separating the positive electrode sheet and the negative electrode sheet to prevent them from contacting and short - circuiting. The separator may be various separator materials suitable for batteries in the art. Exemplarily, the separator includes but is not limited to at least one of polypropylene and polyethylene.

[0127] Power - consuming device

[0128] The present invention further provides a power - consuming device including the battery. The battery serves as the power supply of the power - consuming device.

[0129] The power - consuming device refers to any device that can utilize electrical energy and convert it into other forms of energy such as mechanical energy, thermal energy, and light energy, such as electric motors, thermal engines, and electric light sources. Specifically, it may include but is not limited to mobile devices, electric vehicles, electric trains, ships, satellites, energy storage systems, etc. Mobile devices can be mobile phones, laptops, drones, floor - cleaning robots, electronic cigarettes, etc.; electric vehicles can be pure electric vehicles, hybrid electric vehicles, plug - in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.

[0130] The present invention will be further elaborated with specific embodiments below. It should be noted that unless otherwise specified, the following sintering is carried out in an air atmosphere:

[0131] Example 1

[0132] This example provides a lithium - ion battery, and the specific preparation method is as follows:

[0133] (1) Preparation of the positive electrode sheet

[0134] Preparation of olivine - type phosphate lithium iron manganese phosphate: Mix MnSO4, FeSO4, and H3PO4 in a molar ratio of 6:4:10, add water and mix to prepare a mixed solution with a transition metal element concentration of 1M. Then add ascorbic acid and LiOH, where the addition amount of ascorbic acid is 0.2% of the total molar amount of MnSO4, FeSO4, and H3PO4, and the addition amount of LiOH is 3 times the molar amount of H3PO4. After the obtained mixture is stirred at 70 °C for 6 h, it is pressurized and heated to 150 °C for reaction for 10 h, the solid is separated and dried. Then the obtained powder is dispersed in water, a carbon source with a mass of 21 wt% of the powder is added, spray - dried, and finally calcined at 800 °C for t h in a nitrogen atmosphere to obtain carbon - coated lithium iron manganese phosphate;

[0135] The value of t and the selection of the carbon source are shown in Table 1.

[0136] Preparation of lithium-containing nickel cobalt manganese oxide: Nickel acetate, cobalt acetate, manganese acetate and sodium hydroxide were mixed and dissolved uniformly in water according to a molar ratio of 6:1:3:10, reacted at 80 °C for 24 h, and the solid was separated. The obtained precursor with an average particle size of 3.5 μm was mixed uniformly with lithium hydroxide according to the stoichiometric ratio, and then calcined in an air atmosphere at n °C for 8 h to obtain nickel cobalt manganese oxide;

[0137] Among them, the value of n is shown in Table 1.

[0138] Preparation of the positive electrode sheet: The obtained olivine-type phosphate and NCM were mixed according to the ratio in Table 1 and used as the positive electrode active material. The positive electrode active material, binder PVDF, and conductive agent SP were mixed according to a mass ratio of 97:2:1, dispersed in NMP to obtain a positive electrode slurry. The positive electrode slurry was coated on both sides of the aluminum foil, and then roll-pressed and cut to obtain the positive electrode sheet.

[0139] (2) Preparation of the negative electrode sheet

[0140] Artificial graphite with a particle size of 12 μm of the negative electrode active material, conductive agent SP, and binder CMC were mixed according to a mass ratio of 96.4:1:2.6, dispersed in deionized water to obtain a negative electrode slurry. The negative electrode slurry was coated on both sides of the copper foil, dried, roll-pressed and cut to obtain the negative electrode sheet.

[0141] (3) Preparation of the electrolyte

[0142] Ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) were mixed according to a volume ratio of 1:1:1 to obtain a mixed organic solvent. Then, dry lithium salt LiPF6 was dissolved in the above mixed organic solvent to prepare an electrolyte with a LiPF6 concentration of 1 mol / L.

[0143] (4) Preparation of the separator

[0144] A polyethylene (PE) separator was used.

[0145] (5) Assembly and formation

[0146] The above positive electrode sheet, separator, and negative electrode sheet were stacked in sequence, and the separator was placed between the positive and negative electrode sheets to play a role in isolation, and then wound to obtain a bare battery cell; the bare battery cell was placed in an outer packaging shell, dried, injected with electrolyte, and obtained a lithium-ion battery through processes such as vacuum packaging, standing, formation, and shaping.

[0147] Examples 2 to 27 and Comparative Examples 1 to 2

[0148] These examples and comparative examples all provide a lithium-ion battery, and the preparation method is similar to that of Example 1. The differences are as follows:

[0149] When preparing lithium iron manganese phosphate of olivine type phosphate, adjust the molar ratio of MnSO4, FeSO4 and H3PO4 according to the chemical structural formula of lithium iron manganese phosphate. The chemical structural formula of lithium iron manganese phosphate, the value of t and the selection of carbon source are shown in Table 1;

[0150] When preparing lithium nickel cobalt manganese oxide of lithium-containing oxide, fix the ratio of the sum of the molar amounts of nickel acetate, cobalt acetate and manganese acetate to the molar amount of sodium hydroxide, and adjust the molar ratio of nickel acetate, cobalt acetate and manganese acetate according to the chemical structural formula of lithium nickel cobalt manganese oxide. The chemical structural formula of lithium nickel cobalt manganese oxide and the value of n are shown in Table 1;

[0151] When preparing the positive electrode sheet, the mass ratios of the positive electrode active material (i.e., the main positive electrode material), the binder and the conductive agent are shown in Table 1.

[0152] Table 1

[0153]

[0154]

[0155]

[0156] Using the above method to detect the peak position difference (a) of the (131) crystal plane, the mass content (b) of lithium nickel cobalt manganese oxide in the positive electrode material, and the intensity ratio (c) of the (003) diffraction peak to the (104) diffraction peak in the XRD pattern of the positive electrode material in the XRD patterns of the positive electrode sheets in each example and comparative example at 80% SOC and 20% SOC states of the battery. The test results are shown in Table 2.

[0157] Perform performance tests on the lithium-ion batteries of each example and comparative example. The test results are shown in Table 2. The specific test methods are as follows:

[0158] High-temperature cycle performance test: After standing the lithium-ion battery at 45 °C for 120 min, perform charge and discharge according to the following procedure: constant current and constant voltage full charge at 1C, cut-off voltage 4.25V, cut-off current 0.33C, stand for 20 min, and then constant current discharge at 1C to 2.5V; take the above charge and discharge as one cycle, perform cycle charge and discharge, take the discharge capacity of the first cycle at 1C as the initial first-cycle discharge capacity, and the ratio of the discharge capacity after 100 cycles of 1C charge and discharge to the initial first-cycle discharge capacity as the capacity retention rate of the battery after 100 cycles at high temperature;

[0159] High-temperature storage performance test: Constant current and constant voltage full charge at 0.33C under the condition of 25°C, cut-off voltage 4.25V, cut-off current 0.33C, stand for 20 min, then discharge at 0.33C constant current to 2.5V. The above is one cycle, repeat for two cycles, take the capacity e of the second cycle. Constant current and constant voltage full charge at 0.33C under the condition of 25°C, cut-off voltage 4.25V, cut-off current 0.33C. The battery is transferred to an incubator at 60°C and left for 7 days, then transferred to an incubator at 25°C and stand for 4 h, discharge at 0.33C constant current to 2.5V at 25°C, take the capacity f, then constant current and constant voltage full charge at 0.33C, cut-off voltage 4.25V, cut-off current 0.33C, stand for 20 min, then discharge at 0.33C constant current to 2.5V, take the capacity g. f / e is the capacity retention rate after storage, and g / e is the capacity recovery rate after storage.

[0160] Table 2

[0161]

[0162]

[0163] For the batteries prepared in each embodiment of the present invention, the capacity retention rate after 100 cycles at 1C at 45°C is ≥90%, the capacity retention rate after storage at 60°C for 7 days is ≥83%, and the capacity recovery rate after storage at 60°C for 7 days is ≥80%. It can be seen that the batteries containing the positive electrode sheet of the present invention have excellent high-temperature cycle and storage performance.

[0164] From the comparison between Examples 1-7 and Comparative Examples 8-13, and the comparison between Examples 14-15 and Comparative Examples 16-21, it can be seen that when the peak position difference (a) of the (131) crystal plane in the XRD pattern of the positive electrode sheet, the mass content (b) of lithium nickel cobalt manganate in the positive electrode material, and the intensity ratio (c) of the (003) diffraction peak to the (104) diffraction peak in the XRD pattern of the positive electrode material satisfy the preferred ranges described in the present invention in the 80% SOC and 20% SOC states of the battery, the high-temperature cycle and storage performance of the battery are relatively better.

[0165] From the comparison between Examples 1-7 and Examples 14-15, and the comparison between Examples 8-13 and Comparative Examples 16-21, it can be seen that when the battery satisfies 0.008 ≤ a (c / 1.2) ·b ≤ 0.036, the high-temperature cycle and storage performance of the battery are relatively better.

[0166] According to Comparative Examples 1-2, even when the peak position difference (a) of the (131) crystal plane in the XRD pattern of the positive electrode sheet, the mass content (b) of lithium nickel cobalt manganate in the positive electrode material, and the intensity ratio (c) of the (003) diffraction peak to the (104) diffraction peak in the XRD pattern of the positive electrode material are respectively in the appropriate ranges in the 80% SOC and 20% SOC states of the battery, but when a (c / 1.2)·When the value of b exceeds the range of 0.004 to 0.190, both the high-temperature cycling and storage performance of the battery are relatively poor.

[0167] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this article rather than limiting the protection scope of this article. Although the present application has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of this article can be modified or equivalently replaced, but they do not depart from the essence and scope of the technical solutions of this article.

Claims

1. A battery, characterized in that, including a positive electrode sheet, the positive electrode sheet including a positive electrode current collector and a positive electrode material located on at least one surface of the positive electrode current collector, the positive electrode material including a positive electrode active material, the positive electrode active material including olivine-type phosphate and lithium nickel cobalt manganese oxide, the battery satisfying: 0.004 ≤ a (c / 1.2) ·b ≤ 0.190, wherein, a = a2 - a1, a1 and a2 are respectively the peak positions of the (131) crystal plane in the XRD patterns of the positive electrode sheet at the 20% SOC and 80% SOC states of the battery, with the unit of °; b is the mass content of lithium nickel cobalt manganese oxide in the positive electrode material, dimensionless; c is the intensity ratio of the (003) diffraction peak to the (104) diffraction peak in the XRD pattern of the positive electrode material, dimensionless.

2. The battery according to claim 1, wherein, The battery satisfies: 0.008 ≤ a (c / 1.2) ·b ≤ 0.

036.

3. The battery according to claim 1, characterized in that, The range of a is 0.05° to 0.20°.

4. The battery according to claim 3, characterized in that, The range of a is 0.10° to 0.15°.

5. The battery according to claim 1, characterized in that, The range of b is 0.01 to 0.

50.

6. The battery according to claim 5, characterized in that, The range of b is 0.05 to 0.

20.

7. The battery according to claim 1, characterized in that, The range of c is 0.5 to 1.

8.

8. The battery according to claim 7, wherein The range of c is 1.0 to 1.

5.

9. The battery according to claim 1, characterized in that, satisfying at least one of the following conditions: S1. The range of a1 is 35.0 to 35.9; S2. The range of a2 is 35.2 to 36.0; S3. The general structural formula of the lithium nickel cobalt manganese oxide is: LiNi x Co y Mn z M (1-x-y-z) O2, where 0 < x < 1, 0 < y < 1, 0 < z < 1, 0 ≤ 1 - x - y - z < 1, and the range of x / y is 4.5 to 7; M is a doping element selected from at least one of Al, W, Mg, Sr, and Zr; S4. The olivine-type phosphate includes at least one of lithium iron manganese phosphate and doped lithium iron manganese phosphate; S5. The molar content of manganese element in the olivine-type phosphate in the total transition metal elements is 60% to 85%; S6. The average primary particle size range of the olivine-type phosphate is 80 to 200 nm; S7. The Dv50 particle size range of the lithium nickel cobalt manganese oxide is 2.5 to 4.5 μm; S8. The mass content range of the olivine-type phosphate in the positive electrode material is 0.46 to 0.95; S9. The battery further includes a negative electrode sheet, the negative electrode sheet including a negative electrode active material; the negative electrode active material includes graphite, and the average particle diameter of the graphite is 8 to 13 μm.

10. An electrical device, characterized in that, comprising the battery according to any one of claims 1 to 9.

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