Cathode foil, lithium-ion battery and power-consuming device

Abstract

Cathode foil, characterized in that it comprises a cathode collector and a cathode material applied to the cathode collector, wherein the cathode material comprises an active cathode material, the active cathode material comprising a lithium manganese iron phosphate agglomerate and a ternary material, wherein the cathode foil fulfills the following: 0.004 ≤ a × b × c < 0.230, where a is a dimensionless peak area ratio of diffraction peaks of a (211) crystal plane to a (131) crystal plane in an XRD spectrum of the active cathode material; where b is a dimensionless mass fraction of Ni element in the active cathode material; and where c is a dimensionless mass ratio of the lithium-manganese-iron-phosphate agglomerate to the ternary material; wherein a chemical formula of the lithium manganese iron phosphate agglomerate LiMn x Fe 1-xPO4 where 0 < x < 1.

Description

Technical field

[0001] The present invention relates to the technical field of batteries, in particular a cathode foil, a lithium-ion battery and a power-consuming device. Technical background

[0002] Lithium manganese iron phosphate (LMFP) is an improved lithium iron phosphate material characterized by a high operating voltage range, large theoretical specific capacity, good thermal and chemical stability, broad availability, and low cost, making it one of the most important active cathode materials in research. LMFP agglomerates are secondary particles aggregated from a set of two or more primary particles and exhibiting an agglomerated state. Compared to non-agglomerated LMFP primary particles, the use of LMFP agglomerates can improve the solid-state transfer capacity of a cathode system, reduce battery impedance, and enhance kinetic performance.However, manganese dissolves in the LMFP agglomerates during charging and discharging, especially when the manganese content in the active cathode material is high. This leads to an increase in defects in the cathode material and oxidation of the electrolyte solution. This, in turn, makes the battery susceptible to gas production, which impairs its performance and safety. Therefore, it is necessary to develop a technology that reduces gas production from the LMFP agglomerate system. Content of the invention

[0003] The purpose of the present invention is to provide a cathode foil, a lithium-ion battery and a power-consuming device by overcoming the above shortcomings in the prior art, so that a battery comprising the cathode foil has both low gas production and high safety performance.

[0004] To achieve the above purpose, the present invention, according to a first aspect, provides a cathode foil comprising a cathode collector and a cathode material applied to the cathode collector, wherein the cathode material comprises an active cathode material, the active cathode material comprising a lithium manganese iron phosphate agglomerate and a ternary material, wherein the cathode foil fulfills the following: 0.004≤a×b×c<0.230, where a is a dimensionless peak area ratio of the diffraction peaks of a (211) crystal plane to a (131) crystal plane in an XRD spectrum of the active cathode material; where b is a dimensionless mass fraction of Ni element in the active cathode material; where c is a dimensionless mass ratio of the lithium-manganese-iron-phosphate agglomerate to the ternary material.

[0005] According to a second aspect, the present invention provides a lithium-ion battery comprising a cathode foil as described above.

[0006] According to a third aspect, the present invention provides a power-consuming device comprising a lithium-ion battery as described above.

[0007] In comparison to the prior art, the present invention has the following effects: In the present invention, the LMFP agglomerate is mixed with the ternary material and the peak area ratio of the diffraction peaks of the (211) crystal plane to the (131) crystal plane in the XRD spectrum of the active cathode material, the mass fraction of the Ni element in the active cathode material and the mass ratio of the lithium manganese iron phosphate agglomerate to the ternary material are controlled such that they satisfy a certain relationship, so that the cathode foil can significantly reduce gas production after application in a battery, and at the same time ensures that the battery has a high safety performance. Description of embodiments

[0008] The technical solution in the embodiments of the present invention is explained clearly and completely below, so that the purpose, the technical solutions, and the advantages of the embodiments of the present invention become clearer. Obviously, the described embodiments do not represent all embodiments, but only a subset of the embodiments of the present invention. All other embodiments that a person skilled in the art in this field could obtain from the embodiments in the present invention without any creative work should be considered to be covered by the scope of protection of the present invention.

[0009] The present invention includes, among the technical features described in an open manner, a closed technical solution with the listed features, and also an open technical solution with the listed features.

[0010] Within the scope of the present invention, a numerical interval is considered continuous within said numerical interval unless otherwise specified, and includes a minimum and a maximum value of the range, as well as each value between these minimum and maximum values. If the range refers to an integer, every integer between the minimum and maximum values ​​of the range is included. If several ranges are specified to describe a feature or property, the ranges may also be combined. In other words, unless otherwise specified, all ranges disclosed herein are to be understood as encompassing all subranges contained therein.

[0011] The specific dispersion and mixing treatments are not specifically limited within the scope of the present invention.

[0012] The reagents or instruments used without manufacturer information are all commercially available products on the market.

[0013] In the present invention, the terms “first”, “second”, and similar expressions are not used to limit the number of times. cathode foil

[0014] The present invention provides a cathode foil comprising a cathode collector and a cathode material applied to the cathode collector, wherein the cathode material comprises an active cathode material, the active cathode material comprising a lithium manganese iron phosphate agglomerate and a ternary material, wherein the cathode foil fulfills the following: 0.004≤a×b×c<0.230, where a is a dimensionless peak area ratio of the diffraction peaks of a (211) crystal plane to a (131) crystal plane in an XRD spectrum of the active cathode material; where b is a dimensionless mass fraction of Ni element in the active cathode material; where c is a dimensionless mass ratio of the lithium-manganese-iron-phosphate agglomerate to the ternary material.

[0015] Both the (211) and (131) crystal planes are characteristic crystal planes of LMFP agglomerates, with the (211) crystal plane representing the manganese-poor phase. The (131) crystal plane typically corresponds to a major phase of LMFP, closely resembling the crystal structure of standard LiMnPO4, and features one of the typical characteristic peaks of the olivine structure. The relative content of the manganese-poor phase can be semi-quantitatively assessed by the peak area ratio of the diffraction peaks of the (211) and (131) crystal planes. A decreasing ratio indicates a decreasing relative content of the manganese-poor phase, an increasing relative content of the manganese-rich phase, and a closer resemblance of the LMFP structure to LiMnPO4, leading to an increased risk of manganese precipitation and, consequently, increased gas production.

[0016] After the addition of ternary materials, Ni ions are introduced into the active cathode material. Ni ions have a stronger catalytic oxidation activity than Mn ions in the LMFP agglomerates, which favors the oxidation of proton hydrogen, alters the gas production pathway, generates absorbable gases such as CO and CO2, and reduces the generation of non-absorbable gases such as H2, thus decreasing gas production after the cathode foil is used in the battery. However, the mass fraction (b) of the Ni element in the active cathode material is too high to increase heat production and raise the safety risk. The mass ratio of the lithium manganese iron phosphate agglomerate to the ternary material (c) also affects gas production as well as heat production.As the ratio decreases, the relative content of ternary material increases, which improves gas production. However, an excessively high ratio increases heat production and safety risks. Therefore, it is crucial to maintain a balance between a, b, and c. If a×b×c is too small, the battery produces too much gas, and if a×b×c is too large, the battery produces too much heat, reducing its safety performance.

[0017] Determination of lithium manganese iron phosphate (LMFP) agglomerates: The agglomerate state of the primary particles can be observed using scanning electron microscope (SEM) images.

[0018] The value of the peak area ratio (a) of the diffraction peaks of the (211) crystal plane and the (131) crystal plane in the XRD spectrum of the active cathode material can be adjusted by adjusting the ratio of the LMFP agglomerates to the ternary material and the proportion of elements such as Fe and Mn in the structural formula of the LMFP agglomerates.

[0019] Regarding the test method for the peak area ratio (a) of the diffraction peaks of the (211) crystal plane to the (131) crystal plane in the XRD spectrum of the active cathode material, the present invention is not limited, and a person skilled in the art can test the ratio (a) of the diffraction peaks of the (211) crystal plane to the (131) crystal plane in the XRD spectrum of the active cathode material using conventional technical means. The peak area ratio (a) of the diffraction peaks of the (211) crystal plane to the (131) crystal plane in the XRD spectrum of the active cathode material can, for example, be tested by the following method:

[0020] Disassembly of an empty lithium-ion battery to obtain the cathode foil, immersion of the cathode foil in DMC (dimethyl carbonate) at room temperature (25°C, see below) for 60 minutes to remove the remaining electrolyte solution and by-products from the surface of the cathode foil, removal and drying at room temperature and a relative humidity of ≤15%;

[0021] Scraping off the anode material from the surface of the collector and calcining at 450°C for 6 hours to remove the binder and conductive agent and obtain the active cathode material;

[0022] Taking the obtained active cathode material and grinding, sieving and taking a powder sample with 320 mesh (about 40 microns) and placing it in a high-resolution X-ray diffractometer (e.g. Ultima IV from Rigaku), the sample amount being no less than 5 mg to ensure signal intensity;

[0023] The test conditions were defined as follows: copper target, scanner voltage of 40 KV, current of 40 mA, scan range of 5° to 80°, scan speed of 4° / min and XRD calibration using the internal silicon standard procedure;

[0024] Starting the X-ray source and recording the diffraction data, identifying and calculating the ratio of S(211) to S(131) to obtain a, where S(121) and S(131) are the peak areas of the diffraction peaks of the (211) crystal plane and the (131) crystal plane respectively in the XRD spectrum of the active cathode material;

[0025] In the XRD spectrum, the diffraction peak at a position where the diffraction angle 2θ is 36.1±0.1° is the diffraction peak of the (121) crystal plane, and the diffraction peak at a position where the diffraction angle 2θ is 35.3±0.1° is the diffraction peak of the (131) crystal plane.

[0026] The mass fraction of the Ni element (b) in the active cathode material increases. Since Ni ions have a stronger catalytic oxidation activity than Mn ions in the LMFP agglomerates, which favors the oxidation of protons of hydrogen, alters the gas production pathway, generating absorbable gases such as CO and CO2 and reducing the generation of non-absorbable gases such as H2, gas production decreases after the cathode foil is used in the battery. However, doping with Ni also introduces the problem of battery safety performance. At a high Ni content, heat is generated more readily, increasing the risk of thermal runaway of the battery.

[0027] The mass fraction (b) of the Ni element in the active cathode material can be adjusted by adjusting the proportion of the Ni element, the Mn element and / or the Co element in the structural formula of the ternary material and the ratio of the LMFP agglomerates to the ternary material.

[0028] The present invention does not restrict the test method for the mass fraction (b) of the Ni element in the active cathode material, and engineers in the field can determine the mass fraction (b) of the Ni element in the active cathode material using conventional technical means. For example, the mass fraction (b) of the Ni element in the active cathode material can be tested by inductively coupled plasma mass spectrometry (ICP-MS):

[0029] Disassembly of an empty lithium-ion battery to obtain the cathode foil, immersion of the cathode foil in DMC (dimethyl carbonate) at room temperature (25°C, see below) for 60 minutes to remove the remaining electrolyte solution and by-products from the surface of the cathode foil, removal and drying at room temperature and a relative humidity of ≤15%;

[0030] Scraping off the anode material from the surface of the collector and calcining at 450°C for 6 hours to remove the binder and conductive agent and obtain the active cathode material;

[0031] Take an appropriate amount (approximately 0.1 g) of the obtained active cathode material and dissolve it in aqua regia (i.e., a mixture of concentrated nitric acid and concentrated hydrochloric acid in a volume ratio of 3:1, with a percentage by mass of HNO3 in concentrated nitric acid of 65% to 68% and a percentage by mass of HCl in concentrated hydrochloric acid of 36% to 38%). Heat until completely dissolved and fix the volume to 50 mL to obtain a sample solution. Analyze the sample solution using an ICP-MS instrument (e.g., iCAP PRO X from Thermo Fisher Scientific) set to a radio frequency power of 1200 W and a carrier gas flow rate of 0.9 L / min, with the Ni isotope with characteristic mass number 60 as the test object. The Ni content in the sample solution is calculated by comparing a reaction value of the standard solution with that of the sample solution.The mass fraction of the Ni element in the active cathode material is then calculated accordingly.

[0032] In the present invention, the test method for the mass ratio (c) of the lithium manganese iron phosphate agglomerate to the ternary material is not limited, and on-site technicians can test the mass ratio (c) of the lithium manganese iron phosphate agglomerate to the ternary material using conventional technical means. For example, the mass ratio (c) of the lithium manganese iron phosphate agglomerate to the ternary material can be tested by energy scattering spectroscopy (EDS):

[0033] Disassembly of an empty lithium-ion battery to obtain the cathode foil, immersion of the cathode foil in DMC (dimethyl carbonate) at room temperature (25°C, see below) for 60 minutes to remove the remaining electrolyte solution and by-products from the surface of the cathode foil, removal and drying at room temperature and a relative humidity of ≤15%;

[0034] Scraping the cathode material from the surface of the collector to determine the mass fraction of P, Mn, Fe, Ni, Co, Al (if present) in the cathode material using EDS;

[0035] Calculating the mass fraction of LMFP in the cathode material: The chemical formula of LMFP is typically LiMnxFe1-xPO4, where x represents the molar fraction of Mn, calculated based on the total molar amounts of Mn and Fe in lithium manganese iron phosphate. Since the mass fraction is determined using EDS, an approximate Mn / Fe molar ratio must be assumed (e.g., x = 0.5, i.e., equal molar amounts of Mn and Fe, as an initial calculated value; the actual value may need to be adjusted depending on the specific material). Based on the chemical formula and the mass fraction, the total mass fraction of the elements P, Mn, and Fe in the LMFP is calculated.For this purpose, the mass fraction of each element is multiplied by its relative atomic mass ratio in the chemical formula of the LMFP (taking into account the number of atoms) and then added.

[0036] Calculating the mass fraction of the ternary material in the cathode material: The chemical formula of the ternary material is usually LiNi. y Co z M (1-y-z) O2, where M is at least one of Mn and Al. Based on the mass fractions of Ni, Co, and Mn obtained by EDS (the Mn contribution from the LMFP must be subtracted) and the chemical formula of the ternary material, the total mass fraction of the elements Ni, Co, and Mn in the ternary material is calculated. This is done by multiplying the mass fraction of each element by its relative atomic mass ratio in the chemical formula of the ternary material (taking into account the number of atoms) and then adding the results.

[0037] Finally, the total mass fraction of the LMFP is divided by the total mass fraction of the ternary material to obtain the mass ratio of the lithium manganese iron phosphate agglomerate to the ternary cathode material.

[0038] The peak area ratio of the diffraction peaks of the (211) crystal plane to the (131) crystal plane in the XRD spectrum of the active cathode material (a), the mass fraction of the Ni element in the active cathode material (b), and the mass ratio of the lithium-manganese-iron(II) phosphate agglomerate to the ternary material (c) affect the gas production and heat production of the batteries using the above cathode foil to varying degrees, and they also influence each other to some extent. Therefore, it is difficult to achieve a battery with low gas production and low heat production by controlling only a single variable.In the present invention, the peak area ratio (a) of the diffraction peaks of the (211) crystal plane to the (131) crystal plane in the XRD spectrum of the active cathode material, the mass fraction (b) of the Ni element in the active cathode material and the mass ratio (c) of the lithium manganese iron phosphate agglomerate to the ternary material are controlled such that they satisfy the above determined relationship, so that the gas production of the battery with the cathode foil can be significantly reduced, and at the same time ensuring that the battery has a high safety performance.

[0039] For example, the value of a×b×c can be 0.004, 0.006, 0.008, 0.010, 0.025, 0.030, 0.045, 0.050, 0.065, 0.070, 0.085, 0.090, 0.105, 0.110, 0.125, 0.130, 0.145, 0.150, 0.165, 0.170, 0.185, 0.190, 0.205, 0.210, 0.225 or any value in a range between any two of these values.

[0040] In a preferred embodiment, the cathode foil satisfies the following: 0.044 ≤ a×b×c < 0.110. The value of a×b×c is controlled to lie within this specific range in order to better balance gas production and the safety performance of the battery.

[0041] In some of these embodiments, the peak area ratio (a) of the diffraction peaks of the (211) crystal plane to the (131) crystal plane in the XRD spectrum of the active cathode material is in the range of 0.04 to 0.99, for example 0.04, 0.08, 0.10, 0.20, 0.35, 0.40, 0.55, 0.60, 0.75, 0.80, 0.95, 0.99 or any value in a range between two of these values.

[0042] In a preferred embodiment, the peak area ratio (a) of the diffraction peaks of the (211) crystal plane to the (131) crystal plane in the XRD spectrum of the active cathode material is in the range of 0.32 to 0.99.

[0043] If the ratio (a) of the diffraction peaks of the (211) crystal plane to the (131) crystal plane in the XRD spectrum of the active cathode material is in the range of 0.04 to 0.99, and in particular in the range of 0.32 to 0.99, it is possible to ensure a high energy density while enabling lower gas production.

[0044] In some embodiments, the mass fraction (b) of the Ni element in the active cathode material is in the range of 0.004 to 0.440, for example 0.004, 0.006, 0.008, 0.010, 0.035, 0.050, 0.075, 0.100, 0.125, 0.140, 0.165, 0.180, 0.205, 0.220, 0.245, 0.260, 0.285, 0.300, 0.325, 0.340, 0.365, 0.380, 0.405, 0.420, 0.440 or any value in a range between two of these values.

[0045] In a preferred embodiment, the mass fraction (b) of the Ni element in the active cathode material is in the range of 0.015 to 0.350.

[0046] If the mass fraction (b) of the Ni element in the active cathode material is in the range of 0.004 to 0.440, particularly in the range of 0.015 to 0.350, not only can gas production be reduced more effectively, but better battery safety can also be ensured.

[0047] In some embodiments, the mass ratio (c) of the lithium manganese iron phosphate agglomerate to the ternary material is 0.010 to 99,000, for example 0.100, 0.500, 1.000, 5.000, 10.000, 20.000, 30.000, 40.000, 50.000, 60.000, 70.000, 80.000, 90.000, 99.000 or any value in a range between any two of these values.

[0048] In a preferred embodiment, the mass ratio (c) of the lithium manganese iron phosphate agglomerate to the ternary material is 0.428 to 32,000.

[0049] If the mass ratio (c) of the lithium manganese iron phosphate agglomerate to the ternary material is in the range of 0.010 to 99,000, particularly in the range of 0.428 to 32,000, it is more favorable for a balanced gas and heat production.

[0050] In some embodiments, the lithium manganese iron phosphate agglomerate has a chemical formula of LiMnxFe1-xPO4, where 0 < x < 1. x can be 0.25, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 0.95, 0.99, or any value in a range between any two of these values. The lithium manganese iron phosphate agglomerate can be either free of dopants or contain dopants, and the present invention has no restrictions regarding the type of dopants in the lithium manganese iron phosphate agglomerate; for example, the dopants 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 element in the lithium manganese iron phosphate agglomerate; for example, the percentage mass content of the doping element in the lithium manganese iron phosphate agglomerate is 0 to 1%.The lithium manganese iron phosphate agglomerate can be either free of a coating material or coated with the coating material on part or all of its surface, and the present invention does not limit the type of coating material in the lithium manganese iron phosphate agglomerate. The coating material comprises, for example, at least one of carbon (e.g., hard carbon and / or graphene, etc.), silicides (iron silicide (FeSi₂), manganese silicide (MnSi₂)), and metal oxides (aluminum oxide (Al₂O₃), titanium oxide (TiO₂), and zinc oxide (ZnO)). At the same time, the present invention does not limit the content of the coating material in the lithium manganese iron phosphate agglomerate; for example, the percentage by mass of the coating material in the lithium manganese iron phosphate agglomerate may be 0 to 1%.

[0051] In some embodiments, the particle size Dv50 of the lithium manganese iron phosphate agglomerate is 3 to 15 µm, for example 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 or any value in a range between two of these values.

[0052] The present invention does not limit the test method for the particle size Dv50 of the LMFP agglomerate, and the person skilled in the art can test the particle size Dv50 of the LMFP agglomerate using conventional technical means. For example, the particle size Dv50 of the LMFP agglomerate is tested as follows:

[0053] Take and disassemble an empty battery to obtain the cathode foil, dry the cathode foil and collect 0.1 g to 0.2 g of cathode material powder with a spatula and take images of the obtained cathode material powder with a scanning electron microscope (SEM, EV015, Zeiss tungsten thread electron microscope); measure the size of the LMFP agglomerate in the cathode material powder on the SEM images using MEARSURE NANO software and collect the particle size of the LMFP agglomerate using the diagonal scribble method; count the particle size distribution after collecting 100 or more samples and calculate the particle size-related parameter of the LMFP agglomerate as Dv50.

[0054] In the present invention, the manufacturing process for the lithium manganese iron phosphate agglomerate is not limited, and a person skilled in the art can produce and obtain the lithium manganese iron phosphate agglomerate using conventional technical means. For example, the manufacturing process for the lithium manganese iron phosphate agglomerate comprises the following steps:

[0055] Mixing an iron-manganese phosphate precursor and a lithium source, grinding to powder, performing an initial sintering and subsequent grinding, spraying and drying to obtain a lithium-manganese iron phosphate intermediate;

[0056] Perform a second sintering and coating with the obtained lithium manganese iron phosphate intermediate to obtain a lithium manganese iron phosphate agglomerate.

[0057] The iron-manganese phosphate precursor contains Mn, Fe, and P in the desired stoichiometric ratio (i.e., the ratio of these three elements in the iron-manganese phosphate precursor is the same as the ratio of these three elements in the obtained lithium-manganese-iron-phosphate agglomerate, and other similar expressions are the same). The iron-manganese phosphate precursor can be obtained by industrially known processes, such as solid-state or co-precipitation processes or spray drying processes. For example, the preparation process of the iron-manganese phosphate precursor includes the following steps:

[0058] Dissolve a manganese source, an iron source, and a phosphorus source in deionized water in a stoichiometric ratio. Add a suitable complexing agent and a precipitating agent while stirring. Adjust the pH to 6.0 to 6.5 and allow the reaction to produce a precursor of Mn₂Fe₁₁PO₄. The manganese source includes, among others, manganese sulfate and manganese acetate; the iron source includes, among others, ferrous sulfate and ferric chloride; the phosphorus source includes, among others, phosphoric acid and ammonium phosphate; the complexing agent includes, among others, oxalic acid; and the precipitating agent includes, among others, ammonia.

[0059] In the manufacturing process for the lithium manganese iron phosphate agglomerate, the lithium source used includes, for example, at least one of lithium hydroxide, lithium dihydrogen phosphate, lithium phosphate, lithium carbonate, lithium nitrate, lithium oxalate, lithium citrate and lithium acetate, but is not limited to these.

[0060] In one embodiment, in the manufacturing process of the lithium ferromanganese phosphate agglomerate, the molar amount of the Li element in the lithium source used, based on the total molar amount of the Mn element and the Fe element in the iron-manganese phosphate precursor, can be 1.02 to 1.08, for example 1.02, 1.03, 1.04, 1.05, 1.06, 1.07, 1.08 or any value in a range between two of these values.

[0061] In one embodiment of the lithium manganese iron phosphate agglomerate manufacturing process, the temperature of the first sintering can be set to 500°C to 650°C, the time of the first sintering to 8 hours to 15 hours, and the sintering atmosphere of the first sintering to nitrogen. For example, the temperature of the first sintering is 500°C, 550°C, 600°C, 650°C, or any value in a range between two of these values; and the time of the first sintering is 8 hours, 10 hours, 12 hours, 15 hours, or any value in a range between two of these values.

[0062] In one embodiment of the lithium manganese iron phosphate agglomerate manufacturing process, the temperature of the second sintering can be set to 600°C to 1000°C, the time of the second sintering to 12 hours to 24 hours, and the sintering atmosphere of the second sintering to nitrogen. For example, the temperature of the second sintering is 600°C, 750°C, 900°C, 1000°C, or any value in a range between two of these values; and the time of the second sintering is 12 hours, 15 hours, 18 hours, 20 hours, 24 hours, or any value in a range between two of these values.

[0063] The present invention does not limit the type of milling used in the production of the lithium manganese iron phosphate agglomerate using the iron manganese phosphate precursor, and conventional milling methods, such as ball milling or sand milling, may be selected.

[0064] The present invention does not limit the spraying apparatus and spraying method used in the production of the lithium manganese iron phosphate agglomerate using the iron manganese phosphate precursor, and a conventional spraying method may be chosen. In some embodiments, the spraying method meets the following conditions: a spray pressure of 0.3 to 0.8 MPa and a solids content of the slurry of 20% to 50% (mass ratio).

[0065] In some embodiments, the lithium manganese iron phosphate agglomerate obtained is also washed, dried and crushed after the second sintering.

[0066] In the production of the lithium manganese iron phosphate agglomerate, a certain amount of dopant source (if available) can also be added when mixing the iron manganese phosphate precursor and the lithium source, as required, and the dopant source can be selected from at least one titanium source (e.g. titanium oxide), one magnesium source (e.g. magnesium carbonate), one vanadium source (e.g. vanadium pentoxide), one tungsten source (e.g. ammonium metatungstate), and the like, to obtain the LMFP agglomerate containing a certain amount of the dopant.

[0067] In the production of the lithium manganese iron phosphate agglomerate, the lithium manganese iron phosphate intermediate can be doped with the source of the coating material, and the source of the coating material can be selected from at least one of glucose, sucrose, polyethylene glycol, polyvinyl alcohol, and the like, to obtain the LMFP agglomerate on part or all of the surface with a coating layer. However, the coating can also be omitted.

[0068] In some embodiments, the ternary material is selected from at least one of lithium nickel cobalt manganese oxide or lithium nickel cobalt aluminum oxide.

[0069] In some embodiments, the ternary material has a chemical formula of LiNi. y Co z M (1-y-z )O2. M is at least one of Mn, Al; y is 0.2 to 0.95, for example 0.2, 0.3, 0.5, 0.8, 0.95 or any value in a range between any two of these values; z is 0.01 to 0.25, for example 0.01, 0.03, 0.05, 0.08, 0.1, 0.15, 0.2, 0.25 or any value in a range between any two of these values.

[0070] The ternary material can either be free of dopants or contain dopants, and the present invention does not restrict the type of dopants in the ternary material; for example, it can be selected from at least one of the metallic elements titanium, tin, tantalum, niobium, and lanthanides. At the same time, the present invention does not restrict the content of the dopant in the ternary material, and, for example, the percentage by mass of the dopant in the ternary material is 0 to 1%.

[0071] The ternary material can either be free of a coating material or coated with a coating material on part or all of its surface, the present invention imposing no restriction as to the type of coating material in the ternary material. For example, the coating material can be selected from at least one of the following elements: aluminum (Al), titanium (Ti), tungsten (W), boron (B), phosphorus (P), cobalt (Co), yttrium (Y), silicon (Si). At the same time, the present invention does not limit the content of the coating material in the ternary material, and, for example, the percentage by mass of the coating material in the ternary material is 0 to 1%.

[0072] The ternary material can consist of either primary particles, secondary particles (consisting of more than two primary particles), or a mixture of primary and secondary particles.

[0073] In some embodiments, the particle size Dv50 of the ternary material is 1 to 20 µm, for example 1 µm, 3 µm, 6 µm, 9 µm, 12 µm, 15 µm, 17 µm, 20 µm or any value in a range between two of these values.

[0074] The present invention does not restrict the test method for the particle size Dv50 of the ternary material, and the person skilled in the art can test the particle size Dv50 of the ternary material using conventional technical means. For example, the particle size Dv50 of the ternary material is tested as follows:

[0075] Taking and disassembling an empty battery to obtain the cathode foil, drying the cathode foil and collecting 0.1 g to 0.2 g of cathode material powder with a spatula and taking images of the obtained cathode material powder with a scanning electron microscope (SEM); measuring the size of the ternary material in the cathode material powder on the SEM images using MEARSURE NANO software and collecting the particle size of the ternary material using the diagonal scribble method; counting the particle size distribution after collecting 100 or more samples and calculating the particle size-related parameter of the ternary material as Dv50.

[0076] In the present invention, the manufacturing process for the ternary material is not limited, and a person skilled in the art can produce and obtain the ternary material using conventional technical means. For example, the manufacturing process of the ternary material comprises the following steps:

[0077] Mixing and sintering a precursor of the ternary material and the lithium source to obtain a ternary material.

[0078] The precursor of the ternary material contains Ni, Co, and M in a desired stoichiometric ratio (i.e., the ratio of these three elements in the precursor of the ternary material is the same as the ratio of these three elements in the resulting ternary material, and other similar expressions are the same). The precursor of the ternary material is at least one oxide, one hydroxide, and one carbonate of Ni, Co, and M. For example, the precursor of the ternary material is a hydroxide of Ni, Co, and M.

[0079] The precursor of the ternary material can be obtained using established techniques, such as co-precipitation, gel or solid-phase synthesis. For example, the synthesis process for the ternary material precursor comprises the following steps:

[0080] Dispersing the Ni source, the Co source, and the M source in a solvent to obtain a mixed solution;

[0081] Pump the mixed solution, a strong alkali solution, and a solution of the complexing agent simultaneously into a reaction vessel while stirring, adjusting the pH of the reaction solution to 10 to 13, maintaining a temperature of 25°C to 90°C in the reaction vessel, and protecting the reaction process by passing through an inert atmosphere (e.g., at least one of nitrogen and an inert gas); After completion of the reaction, the precursor of the ternary material is obtained by aging, filtration, washing, and vacuum drying to yield a hydroxide containing Ni, Co, and M.

[0082] In the manufacturing process of the precursor of the ternary material, the Ni source used includes, but is not limited to, at least one of nickel sulfate, nickel nitrate, nickel chloride, nickel oxalate, or nickel acetate.

[0083] And / or the cobalt source used includes at least one of cobalt sulfate, cobalt nitrate, cobalt chloride, cobalt oxalate, cobalt acetate, but is not limited to these.

[0084] And / or the M source used includes at least one Mn source, one Al source, for example the Mn source includes at least one of manganese sulfate, manganese nitrate, manganese chloride, manganese oxalate, manganese acetate; the Al source includes at least one of aluminum nitrate, aluminum sulfate, aluminum chloride, but is not limited to these.

[0085] And / or, if the Ni source, the Co source and the M source are dispersed in a solvent, the solvent used includes, but is not limited to, water;

[0086] And / or the alkali in the strong alkaline solution used includes at least one of sodium hydroxide, potassium hydroxide, but is not limited to these;

[0087] And / or the solution used contains ammonia, but is not limited to it.

[0088] In the preparation of the precursor to the ternary material, the amounts of the Ni source, Co source, and M source used can optionally fulfill the following: molar amount of Ni element : molar amount of Co element : molar amount of M element = (92 to 10) : (5 to 35) : (3 to 85). By adjusting the ratio of the molar amount of Ni element in the Ni source to the total molar amounts of Ni element, Co element, and M element contained in the Ni source, Co source, and M source, the molar ratio of nickel element in the structural formula of the ternary material can be regulated.

[0089] In the production of the ternary material, the Li source used includes at least one of lithium oxide (Li2O), lithium phosphate (Li3PO4), lithium dihydrogen phosphate (LiH2PO4), lithium acetate (CH3COOLi), lithium hydroxide (LiOH), lithium carbonate (Li2CO3), lithium nitrate (LiNO3), but is not limited to these.

[0090] In the production of the ternary material, the ratio of the lithium source used to the precursor of the ternary material is as follows: the molar amount of the Li element : the sum of the molar amounts of the elements Ni, Co and M = (1.05-1.2):1.

[0091] When mixing the precursor of the ternary material and the lithium source, a ball mill or a high-speed mixer can be used for mixing.

[0092] In the production of the ternary material using the precursor for the ternary material, the sintering atmosphere is an inert atmosphere, such as a nitrogen atmosphere, a helium atmosphere, or an argon atmosphere.

[0093] When producing the ternary material using the ternary material precursor, the sintering temperature can be chosen between 750°C and 1000°C and the sintering time between 8 hours and 20 hours.

[0094] In the production of the ternary material, a specific amount of a dopant source (if available) can also be added as required when the precursor of the ternary material and the lithium source are mixed, and the dopant source can be selected from at least a titanium source, a tin source, a niobium source, a tantalum source, a lanthanum metal source, and the like, to obtain the ternary material containing a specific amount of a dopant.

[0095] During the production of the ternary material, the ternary material can also be coated as required. In particular, the coating material is applied to the surface of the ternary material by dry coating (high-temperature solid-state process), and the ternary material is coated with the coating layer formed by the coating material on part or all of its surface. For example, the coating layer comprises at least one element (hereinafter referred to as the "coating element") selected from the following: aluminum (Al), phosphorus (P), silicon (Si), titanium (Ti), tungsten (W), boron (B), cobalt (Co), or yttrium (Y).

[0096] In some embodiments, the percentage by mass of the active cathode material in the cathode material is 80% to 98%, for example 98%, 96%, 94%, 92%, 90%, 88%, 86%, 84%, 82%, 80% or any value in a range between two of these values.

[0097] In addition to the above active cathode material, the cathode material contains a conductive agent and a binder.

[0098] The conductive material in the cathode is used to ensure electrical conductivity, and any conductive material may be used without particular restriction, provided it has suitable electronic conductivity and does not cause any obviously adverse chemical changes in the battery. For example, the conductive material in the cathode comprises at least one of carbon nanotubes, carbon black, graphite, carbon fibers, activated carbon, mesoporous carbon, or fullerenes, wherein the carbon fibers are, for example, carbon nanofibers and the like; and the carbon black is, for example, SP (Super P, hereinafter referred to as "SP"), acetylene black, cotinine black, and the like.

[0099] In some embodiments, the percentage by mass of the conductive medium in the cathode material is 0.1% to 5%, for example 0.1%, 0.5%, 1.0%, 2.0%, 3.0%, 4.0%, 5.0% or any value in a range between two of these values.

[0100] The binder in the cathode material is used to improve the bonding between the particles of the active cathode material and the bonding between the active cathode material and the cathode collector. Any binder may be used without particular restriction, provided it has suitable binder properties and does not cause obviously adverse chemical changes in the battery. For example, the binder in the cathode material layer includes a fluoropolyolefin-based binder, and the fluoropolyolefin-based binder includes, but is not limited to, polyvinylidene fluoride (PVDF), copolymers of vinylidene fluoride, or modified derivatives thereof (e.g., carboxylic acid, acrylic acid, acrylonitrile, and other modifications thereof).

[0101] In some embodiments, the percentage by mass of the binder in the cathode material is 0.1% to 5%, for example 0.1%, 0.5%, 1.0%, 2.0%, 3.0%, 4.0%, 5.0% or any value in a range between two of these values.

[0102] The cathode material can be applied either to one side of the cathode collector or to both sides of the cathode collector.

[0103] The present invention does not impose any special restrictions on the cathode collector, as long as it is electrically conductive, without causing harmful chemical changes in the battery, and can be made of, for example: aluminum, nickel, titanium, stainless steel, burnt carbon; or aluminum or stainless steel that has been surface-treated with carbon, nickel, titanium, silver and the like.

[0104] In the present invention, the cathode foil can be produced using conventional methods. For example, the active cathode material, the conductive agent, and the binder are dispersed in a solvent to obtain a cathode slurry, and the cathode slurry is applied to at least one side of the cathode collector. The cathode foil is obtained after drying, roller pressing, cutting, and other processes. The solvent used to produce the cathode slurry includes, but is not limited to, at least one of N-methylpyrrolidone (NMP) and deionized water. battery

[0105] The present invention further provides a battery comprising a cathode foil, an anode foil and an electrolyte solution;

[0106] The anode foil in the present invention comprises an anode collector and an anode material applied to at least one surface of the anode collector, wherein the anode material comprises an active anode material.

[0107] The present invention has no particular limitations regarding the active anode material. For example, the active anode material comprises at least one of natural graphite, synthetic graphite, microcarbon spheres in the middle phase (MCMB), hard carbon, soft carbon, silicon, SiO₂. e (0 <e<2, z. B. e=1), Silizium-Kohlenstoff-Komplex und Li4Ti5O12, aber nicht darauf beschränkt ist.

[0108] In some embodiments, the percentage by mass of the active anode material is 80% to 99%, for example 99%, 96%, 94%, 92%, 90%, 88%, 86%, 84%, 82%, 80% or any value in a range between two of these values.

[0109] The anode material may also include a conductive agent and / or a binder.

[0110] The conductive material in the anode material is used to ensure electrical conductivity, and any conductive material may be used without particular restriction, provided it has suitable electronic conductivity and does not cause any obviously adverse chemical changes in the battery. For example, the conductive material in the anode material comprises at least one of carbon nanotubes, carbon black, graphite, carbon fibers, activated carbon, mesoporous carbon, or fullerenes, wherein the carbon fibers are, for example, carbon nanofibers and the like; and the carbon black is, for example, SP, acetylene black, cotinine black, and the like.

[0111] In some embodiments, the percentage by mass of the conductive medium in the anode material is 0.1% to 5%, for example 0.1%, 0.5%, 1.0%, 2.0%, 4.0%, 5.0% or any percentage formed in a range between two of these values.

[0112] The binder in the anode material is used to improve the bonding between the particles of the active anode material and the bonding between the active anode material and the anode collector. Any binder may be used without particular restriction, provided it has suitable binder properties and does not cause obviously adverse chemical changes in the battery. For example, the binder in the anode material includes, but is not limited to, at least one of carboxymethylcellulose (CMC), styrene-butadiene rubber (SBR), polyacrylic acid (PAA), polyvinylidene fluoride, polytetrafluoroethylene, polyvinyl butyral, and aqueous acrylic resin.

[0113] In some embodiments, the percentage by mass of the binder in the anode material is 0.1% to 5%, for example 0.1%, 0.5%, 1.0%, 2.0%, 3.0%, 4.0%, 5.0% or any value in a range between two of these values.

[0114] The anode material can be applied either to one side of the anode collector or to both sides of the anode collector.

[0115] The present invention does not impose any special restrictions on the anode collector, as long as it is electrically conductive without causing harmful chemical changes in the battery and can be used, for example: copper, stainless steel, aluminum, nickel, titanium, burnt carbon, or copper or stainless steel, or aluminum-cadmium alloy surface-treated with at least one of carbon, nickel, titanium, silver and the like.

[0116] The electrolyte solution of the present invention can be a variety of electrolyte solutions suitable for batteries. The electrolyte solution comprises an electrolyte and a solvent, wherein the electrolyte typically contains a lithium salt.

[0117] For example, the lithium salt may include, but is not limited to, at least one of the following lithium salts: 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 borate dioxylic acid (LiBOB), lithium difluorophosphate (LiPO2F2), lithium difluorodioxylic acid phosphate (LiDFOP), and / or lithium tetrafluorooxalate phosphate (LiTFOP). The electrolyte concentration in the electrolyte solution can range from 0.5 to 2 mol / L.

[0118] In particular, the solvent may be at least one of, but is not limited to, ethylidene carbonate (EC), methyl ethyl carbonate (EMC), diethyl carbonate (DEC), propylidene carbonate (PC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methylenepropylene carbonate (MPC), ethylenepropylene carbonate (EPC), butylidene carbonate (BC), fluorinated ethylene 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), 4-butyrolactone (GBL), cyclobutane sulfone (SF), dimethyl sulfone (MSM), methyl ethyl sulfone (EMS), and diethyl sulfone (ESE). The percentage by mass of the solvent in the electrolyte solution may be 75% to 85%.

[0119] Furthermore, the electrolyte solution may optionally contain an additive. For example, the additives may include a film-forming anode additive, a film-forming cathode additive, and additives to improve specific battery performance, e.g., additives such as triphenyl phosphate (TPP), dimethyl 2,5-dioxane hexahydroxycarboxylate (DMOHC), and the like to improve the battery's high-temperature performance; and additives such as para-phenylene nitrile (PTMN) to improve the battery's overcharge performance; additives such as dimethyl sulfite (DMS), and the like to improve the battery's low-temperature performance. The percentage by mass of the additives in the electrolyte solution may range from 0.1% to 2%.

[0120] The battery may further include a separator. The separator is located between the cathode foil and the anode foil to keep the cathode foil and the anode foil apart and to prevent them from short-circuiting. The separator may be made of various materials suitable for use as insulating films for batteries according to the prior art. For example, the separator may include at least one of the following materials: polypropylene, polyethylene, Power-consuming device

[0121] The present invention further provides a power-consuming device comprising a battery as described above. The battery serves as an energy source for the power-consuming device.

[0122] A power-consuming device is any device that can utilize electrical energy and convert it into one or more other formative energies such as mechanical energy, thermal energy, light energy, etc., such as an electric motor, an electric heater, an electric light source, and the like. Specifically, it can be a mobile device, an electric vehicle, an electric train, a ship, a satellite, an energy storage system, etc. A mobile device can be a mobile phone, a laptop, a drone, a robotic sweeper, an electronic cigarette, etc. An electric vehicle can be a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck, etc.

[0123] The present invention will be explained in more detail below with reference to specific embodiments. It should be noted that, unless otherwise specified, the subsequent sintering process takes place in an air atmosphere. Example 1

[0124] One embodiment provides a lithium-ion battery which is manufactured as follows: (1) Production of the cathode foil (1.1) Production of the ternary material

[0125] Admitting Ni y Co z M (1-y-z) (OH)2 and lithium hydroxide are placed in a ball mill and the balls are ground into a powder, based on the sum of the molar amounts of the elements Ni, Co and Mn in Ni y Co z M (1-y-z) (OH)2 the molar amount of the Li element in lithium hydroxide is 1.1. Sintering at 800°C for 13 hours in a nitrogen atmosphere to produce LiNi y Co z M (1-y-z)to obtain O2, the ternary target material, where the values ​​of y and z and the types of M elements are listed in Table 1. (1.2) Production of the LMFP agglomerate

[0126] Add the iron-manganese phosphate precursor MnxFe1-xPO4 and lithium hydroxide to a ball mill and grind the balls to a powder, where, based on the total molar amounts of Mn and Fe in the iron-manganese phosphate precursor, the molar amount of Li in the lithium source used is 1.03. Perform the first sintering at 600°C for 10 hours. Mill, spray, and dry the sintered product. Subsequently, perform the second sintering at 700°C for 12 hours, wash, dry, and grind the product to obtain the target agglomerate LiMnxFe1-xPO4, where the values ​​of x are listed in Table 1. (1.3) Production of the cathode foil

[0127] Using the above LMFP agglomerate and ternary material as the active cathode material (the mass ratio of LMFP agglomerate and ternary material is listed in Table 1), mixing the active cathode material, the conductive agent acetylene black and the binder PVDF in a mass ratio of 96:2:2, adding the solvent NMP, stirring and dispersing using a vacuum stirrer to obtain the cathode slurry;

[0128] The cathode slurry was applied to both surfaces of the aluminum foil of the cathode collector, dried at room temperature, then placed in an oven for further drying, and subsequently the cathode foil is produced by cold pressing and cutting. (2) Production of the anode foil

[0129] Mixing the graphite, the conductive agent acetylene black, the binder SBR and the binder PAA in a mass ratio of 96:1:2:1, adding the solvent deionized water, stirring and dispersing using a vacuum stirrer to obtain an anode slurry;

[0130] The anode slurry is applied to both surfaces of the copper foil of the anode collector, dried at room temperature and further dried in an oven, and then cold pressed and cut to obtain the anode foil. (3) Preparation of the electrolyte solution

[0131] Mix ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) in a volume ratio of 3:5:2 to obtain a mixed organic solvent. Dissolve the dried lithium salt LiPF6 in the mixed organic solvent and add dimethyl 2,5-dioxanehexahydroxycarboxylate (DMOHC) to prepare an electrolyte solution containing LiPF6 at a concentration of 1 mol / L and DMOHC at a mass fraction of 8.5%. (4) Production of the separator

[0132] A polyethylene (PE) separator is used. (5) Production of the lithium-ion battery

[0133] The above cathode foil, separator, and anode foil are stacked sequentially, with the separator positioned between the cathode foil and the anode foil to act as insulation, and then wound to form the bare electrical core. The bare electrical core is placed in the outer packaging, dried, and injected with the electrolyte solution. Following vacuum encapsulation, settling, forming, shaping, and other processes, the lithium-ion batteries are obtained, with the forming process carried out as follows:

[0134] Pre-charging the battery to 20% SOC with a constant current of 0.02C;

[0135] Charging the battery to 80% SOC with a constant current of 0.33C;

[0136] Charging the battery to 90% SOC with a constant current of 0.1C;

[0137] Charging the battery to 4.25 V with a constant current of 0.2 C, switching to charging with a constant voltage, with a cut-off current of 0.05 C. Exemplary embodiments 2 to 26 and comparative examples 1 to 2

[0138] The embodiments and the comparative examples all provide a lithium-ion battery, and the manufacturing process is similar to that of embodiment 1, with the following difference: (a) In step (1.1) the values ​​of y and z and the types of M elements are listed in Table 1; (b) In step (1.2) the values ​​of x are listed in Table 1; (c) In step (1.3) the mass ratio of the LMFP agglomerate to the ternary material is shown in Table 1. Table 1 x Type of M element y z Mass ratio of the lithium-manganese-iron-phosphate agglomerate to the ternary material Example 1 0,75 Mn 0,7 0,2 3:7 Example 2 0,63 Mn 0,7 0,2 3:7 Example 3 0,68 Mn 0,5 0,15 7:3 Example 4 0,78 Mn 0,68 0,2 8:2 Example 5 0,66 Mn 0,5 0,15 7:3 Example 6 0,81 Al 0,8 0,1 6:4 Example 7 0,79 Mn 0,5 0,15 4:6 Example 8 0,81 Mn 0,7 0,2 2,5:7,5 Example 9 0,71 Mn 0,7 0,05 7,5:2,5 Example 10 0,61 Mn 0,65 0,2 8:2 Example 11 0,71 Mn 0,68 0,1 1,5:8,5 Example 12 0,67 Mn 0,7 0,2 5:5 Example 13 0,75 Mn 0,75 0,1 3,5:6,5 Example 14 0,52 Mn 0,61 0,1 5:5 Example 15 0,64 Mn 0,71 0,1 9:1 Example 16 0,78 Mn 0,5 0,2 3:7 Example 17 0,68 Mn 0,67 0,15 2,9:7,1 Example 18 0,78 Mn 0,2 0,2 1:9 Example 19 0,77 Mn 0,3 0,1 1:9 Example 20 0,71 Mn 0,7 0,2 0,1:9,9 Example 21 0,6 Mn 0,4 0,12 2,5:7,5 Example 22 0,6 Mn 0,6 0,1 9:1 Example 23 0,85 Mn 0,6 0,1 3:7 Example 24 0,25 Mn 0,7 0,1 9,9:0,1 Example 25 0,68 Mn 0,85 0,1 9,7:0,3 Example 26 0,25 Mn 0,85 0,1 9,9:0,1 Comparative example 1 0,84 Mn 0,85 0,1 7:3 Comparative example 2 0,3 Mn 0,8 0,1 1:9

[0139] The peak area ratios (i.e. a) of the diffraction peaks of the (211) crystal plane to the (131) crystal plane in the XRD spectrum of the active cathode material, the mass fraction (i.e. b) of the Ni element in the active cathode material and the mass ratio (i.e. c) of the lithium manganese iron phosphate agglomerate to the ternary material in the embodiments and the comparative examples are tested by the following procedure, the test results are listed in Table 2:

[0140] (2) Test of the peak area ratio of the diffraction peaks of a (211) crystal plane to a (131) crystal plane in an XRD spectrum of the active cathode material:

[0141] Disassembly of an empty lithium-ion battery to obtain the cathode foil, immersion of the cathode foil in DMC (dimethyl carbonate) at room temperature (25°C, see below) for 60 minutes to remove the remaining electrolyte solution and by-products from the surface of the cathode foil, removal and drying at room temperature and a relative humidity of ≤15%;

[0142] Scraping off the anode material from the surface of the collector and calcining at 450°C for 6 hours to remove the binder and conductive agent and obtain the active cathode material;

[0143] The resulting active cathode material was milled, sieved, and an 8 mg powder sample with a 320 mesh (approximately 40 microns) was taken and placed in a high-resolution X-ray diffractometer (Ultima IV from Rigaku). The test conditions were set as follows: copper target, scanner voltage of 40 kV, current of 40 mA, scan range of 5° to 80°, scan speed of 4° / min, and XRD calibration using the internal silicon standard procedure.

[0144] Starting the X-ray source and recording the diffraction data, identifying and calculating the ratio of S(211) to S(131) to obtain a, where S(121) and S(131) are the peak areas of the diffraction peaks of the (211) crystal plane and the (131) crystal plane respectively in the XRD spectrum of the active cathode material;

[0145] In the XRD spectrum, the diffraction peak at a position where the diffraction angle 2θ is 36.1±0.1° is the diffraction peak of the (121) crystal plane, and the diffraction peak at a position where the diffraction angle 2θ is 35.3±0.1° is the diffraction peak of the (131) crystal plane. (2) Mass fraction of Ni element in the active cathode material:

[0146] Disassembly of an empty lithium-ion battery to obtain the cathode foil, immersion of the cathode foil in DMC (dimethyl carbonate) at room temperature (25°C, see below) for 60 minutes to remove the remaining electrolyte solution and by-products from the surface of the cathode foil, removal and drying at room temperature and a relative humidity of ≤15%;

[0147] Scraping off the anode material from the surface of the collector and calcining at 450°C for 6 hours to remove the binder and conductive agent and obtain the active cathode material;

[0148] Take an appropriate amount (approximately 0.1 g) of the resulting active cathode material and dissolve it in aqua regia (i.e., a mixture of concentrated nitric acid and concentrated hydrochloric acid in a volume ratio of 3:1, with a percentage by mass of HNO₃ in concentrated nitric acid of 67% and a percentage by mass of HCl in concentrated hydrochloric acid of 37%). Heat until completely dissolved and fix the volume to 50 mL. Analyze the sample using an ICP-MS instrument (iCAP PRO X from Thermo Fisher Scientific) set to a radio frequency power of 1200 W and a carrier gas flow rate of 0.9 L / min, with the Ni isotope with characteristic mass number 60 as the test object. The Ni content is calculated by comparing a reaction value of the standard solution with that of the sample solution. Subsequently, the mass fraction of the Ni element in the active cathode material is calculated accordingly. (3) Mass ratio of the lithium-manganese-iron-phosphate agglomerate to the ternary material

[0149] Disassembly of an empty lithium-ion battery to obtain the cathode foil, immersion of the cathode foil in DMC (dimethyl carbonate) at room temperature (25°C, see below) for 60 minutes to remove the remaining electrolyte solution and by-products from the surface of the cathode foil, removal and drying at room temperature and a relative humidity of ≤15%;

[0150] Scraping the cathode material from the surface of the collector to determine the mass fraction of P, Mn, Fe, Ni, Co, Al (if present) in the cathode material using EDS;

[0151] Calculating the mass fraction of LMFP in the cathode material: The chemical formula of LMFP is typically LiMnxFe1-xPO4, where x represents the molar fraction of Mn, calculated based on the total molar amounts of the elements Mn and Fe in lithium manganese iron phosphate; The chemical formula of LMFP is typically LiMn x Fe 1-xPO4, where x represents the molar fraction of Mn, calculated based on the total molar amounts of the elements Mn and Fe in lithium manganese iron phosphate; since the mass fraction is determined using EDS, an approximate Mn / Fe molar ratio must be assumed (e.g., x = 0.5, i.e., equal molar amounts of Mn and Fe, as an initial calculated value; the actual value may need to be adjusted depending on the specific material). Based on the chemical formula and the mass fraction, the total mass fraction of the elements P, Mn, and Fe in the LMFP is calculated. This is done by multiplying the mass fraction of each element by its relative atomic mass ratio in the chemical formula of the LMFP (taking into account the number of atoms) and then adding the results.

[0152] Calculating the mass fraction of the ternary material in the cathode material: The chemical formula of the ternary material is usually LiNi. y Coz M (1-y-z) O2, where M is at least one of Mn and Al. Based on the mass fractions of Ni, Co, and Mn obtained by EDS (the Mn contribution from the LMFP must be subtracted) and the chemical formula of the ternary material, the total mass fraction of the elements Ni, Co, and Mn in the ternary material is calculated. This is done by multiplying the mass fraction of each element by its relative atomic mass ratio in the chemical formula of the ternary material (taking into account the number of atoms) and then adding the results.

[0153] Finally, the total mass fraction of the LMFP is divided by the total mass fraction of the ternary material to obtain the mass ratio of the lithium manganese iron phosphate agglomerate to the ternary cathode material.

[0154] The performance test of the lithium-ion battery obtained from each embodiment and each comparison example is performed. The test results are listed in Table 2, and the specific test procedures are as follows:

[0155] Peak temperature test: DSC (Differential Scanning Calorimetry). The cathode foil is placed in an aluminum or platinum crucible, and a tight seal is ensured to prevent the escape of volatile substances. Temperature calibration is performed using standard substances (e.g., indium, tin, zinc) with known melting points. The starting temperature is set to 5°C and the final temperature to 600°C. The temperature increase rate is typically 5°C / min. An inert gas (e.g., nitrogen) is used as the test atmosphere. Test instrument: Germany NETZSCH, Model: DSC214;

[0156] Testing of storage gas production: Using a LAND system to charge the battery to 4.25 V at a constant current (0.2C), and using a dehydration method to test the battery's volume after full charge. Wipe the battery and place it in an oven at 60°C for 42 days. Afterward, charge the battery to 4.25 V using the LAND system at a constant current (0.2C). Measure the volume using the dehydration method. Gas production = (volume after storage - initial volume) / battery capacity, gas production in mL / Ah. Table 2 a b c a×b×c Gas production mL / Ah Peak temperature °C Example 1 0,7390 0,3041 0,4379 0,0984 2,54 233,6 Example 2 0,5651 0,3082 0,4298 0,0749 2,53 232,2 Example 3 0,3201 0,0931 2,3342 0,0696 2,43 230,4 Example 4 0,3269 0,0813 4,1232 0,1096 2,51 231,4 Example 5 0,3203 0,0925 2,3322 0,0691 2,42 230,1 Example 6 0,3633 0,1999 1,5123 0,1098 2,41 233,0 Example 7 0,3348 0,2012 0,6653 0,0448 2,41 232,2 Example 8 0,7843 0,3212 0,3298 0,0831 4,33 233,7 Example 9 0,2976 0,1091 3,0123 0,0978 4,32 236,1 Example 10 0,2557 0,0812 4,0156 0,0834 4,34 236,4 Example 11 0,7831 0,3576 0,1798 0,0503 4,35 240,2 Example 12 0,8848 0,2122 1,0216 0,1918 5,32 239,1 Example 13 0,7444 0,2975 0,5479 0,1213 5,37 238,1 Example 14 0,7096 0,1832 1,0215 0,1328 5,23 242,3 Example 15 0,5760 0,0435 8,9132 0,2233 5,19 231,5 Example 16 0,3345 0,2085 0,4308 0,0300 5,23 243,6 Example 17 0,3450 0,2801 0,4131 0,0399 5,68 247,8 Example 18 0,8808 0,1201 0,1099 0,0116 5,78 243,1 Example 19 0,8493 0,1698 0,1121 0,0162 5,81 243,2 Example 20 0,8875 0,4381 0,0121 0,0047 5,67 253,1 Example 21 0,4597 0,1924 0,3292 0,0291 5,71 241,2 Example 22 0,0882 0,0325 9,0121 0,0258 5,83 242,1 Example 23 0,3075 0,2456 0,4221 0,0319 5,78 245,1 Example 24 0,0404 0,0041 98,9972 0,0164 5,64 244,5 Example 25 0,2850 0,0147 32,2312 0,1350 7,98 241,2 Example 26 0,0371 0,0046 98,9972 0,0169 8,52 257,1 Comparative example 1 0,9700 0,1483 2,3233 0,3342 8,12 290,0 Comparative example 2 0,0494 0,4323 0,1103 0,0024 22,00 223,1

[0157] For the batteries produced in each embodiment of the present invention, the gas production after 42 days of storage at 60°C is ≤ 8.6 ml / Ah, and the peak temperature of the cathode foil is ≤ 258°C. It can be seen that the batteries containing the cathode foil of the present invention exhibit low gas production and good safety performance.

[0158] As can be seen from embodiments 1 to 7, which are compared with embodiments 8 to 11, and embodiments 12 to 16, which are compared with embodiments 17 to 25, it is more advantageous for balancing gas production and heat production if the peak area ratio of the diffraction peaks of the (211) crystal plane to the (131) crystal plane in the XRD spectrum of the active cathode material, the mass fraction of the Ni element in the active cathode material and the mass ratio of the lithium manganese iron phosphate agglomerate to the ternary material meet the preferred ranges described in the present invention.

[0159] As can be seen from embodiments 1 to 7, which are compared with embodiments 12 to 16, and from embodiments 8 to 11, which are compared with embodiments 17 to 25, the gas and heat production of the battery is better balanced when the cathode foil meets 0.044 ≤ a×b×c < 0.110.

[0160] As can be seen from comparative examples 1 and 2, the peak area ratio of the diffraction peaks of the (211) crystal plane to the (131) crystal plane in the XRD spectrum of the active cathode material, the mass fraction of the Ni element in the active cathode material, and the mass ratio of the lithium manganese iron phosphate agglomerate to the ternary material are all within the correct range. However, if the value of a×b×c exceeds the range of 0.004 ≤ a×b×c < 0.230, the gas or heat production of the battery is relatively high, and the balance between gas production and safety performance cannot be achieved.

[0161] Finally, it should be noted that the above-mentioned embodiments are used only to illustrate the technical solutions of the present invention and not to limit the scope of protection of the present invention. Although the present invention is described in detail with reference to the preferred embodiments, a person with ordinary technical knowledge in the field should understand that the technical solutions of the present invention can be modified or replaced with equivalent solutions without departing from the substance and scope of the technical solutions of the present invention.

[0162] The present invention relates to a cathode foil, a battery, and a power-consuming device comprising the cathode foil, and relates to the technical field of batteries. The cathode foil in the present invention comprises a cathode collector and a cathode material applied to the cathode collector, wherein the cathode material comprises an active cathode material, the active cathode material comprising a lithium manganese iron phosphate agglomerate and a ternary material.A peak area ratio a of diffraction peaks of a (211) crystal plane to a (131) crystal plane in an XRD spectrum of the active cathode material, a mass fraction b of Ni element in the active cathode material and a mass ratio c of the lithium manganese iron phosphate agglomerate to the ternary material are controlled such that they satisfy 0.004 ≤ a×b×c < 0.230, whereby the battery with the cathode foil can exhibit both low gas production and high safety performance.

Claims

Cathode foil, characterized in that it comprises a cathode collector and a cathode material applied to the cathode collector, wherein the cathode material comprises an active cathode material, the active cathode material comprising a lithium manganese iron phosphate agglomerate and a ternary material, wherein the cathode foil satisfies the following: 0.004 ≤ a × b × c < 0.230, where a is a dimensionless peak area ratio of diffraction peaks of a (211) crystal plane to a (131) crystal plane in an XRD spectrum of the active cathode material; where b is a dimensionless mass fraction of Ni element in the active cathode material; and where c is a dimensionless mass ratio of the lithium-manganese-iron-phosphate agglomerate to the ternary material; wherein a chemical formula of the lithium manganese iron phosphate agglomerate LiMn x Fe 1-x PO 4 where 0 < x < 1. Cathode foil according to claim 1, characterized in that the cathode foil fulfills the following: 0.044 ≤ a×b×c < 0.

110. Cathode foil according to claim 1, characterized in that a lies in a range from 0.04 to 0.

99. Cathode foil according to claim 3, characterized in that a lies in a range of 0.32 to 0.

99. Cathode foil according to claim 1, characterized in that b lies in a range from 0.004 to 0.

440. Cathode foil according to claim 5, characterized in that b lies in a range of 0.015 to 0.

350. Cathode foil according to claim 1, characterized in that c lies in a range from 0.010 to 99,000. Cathode foil according to claim 7, characterized in that c lies in a range from 0.428 to 32,000. Cathode foil according to claim 1, characterized in that the ternary material is selected from at least one of lithium nickel cobalt manganese oxide and lithium nickel cobalt aluminum oxide. Cathode foil according to claim 1, characterized in that the lithium manganese iron phosphate agglomerate comprises a coating material, wherein the coating material comprises at least one of carbon, silicide and metal oxide. Cathode foil according to claim 10, characterized in that the percentage mass content of the coating material in the lithium manganese iron phosphate agglomerate is 0 to 1%. Cathode foil according to claim 1, characterized in that a particle size Dv50 of the lithium manganese iron phosphate agglomerate is 3 to 15 µm. Cathode foil according to claim 1, characterized in that the chemical formula of the ternary material is LiNiyCozM(1-yz)O2, wherein M is at least one of Mn, Al, wherein y is 0.2 to 0.95, and z is 0.01 to 0.

25. Cathode foil according to claim 1, characterized in that the ternary material comprises a coating material, wherein the coating material comprises at least one element of aluminium, titanium, tungsten, boron, phosphorus, cobalt, yttrium and silicon. Cathode foil according to claim 14, characterized in that the percentage mass content of the coating material in the ternary material is 0 to 1%. Cathode foil according to claim 1, characterized in that a particle size Dv50 of the ternary material is 1 to 20 µm. Cathode foil according to claim 1, characterized in that the percentage mass content of the active cathode material in the cathode material is 80% to 98%. Cathode foil according to claim 1, characterized in that the cathode material comprises a conductive agent and a binder, wherein the percentage by mass of the conductive agent in the cathode material is 0.1 to 5%, and wherein the percentage by mass of the binder in the cathode material is 0.1 to 5%. Lithium-ion battery, characterized in that it comprises a cathode foil according to one of claims 1 to 18. Power-consuming device, characterized in that it comprises a lithium-ion battery according to claim 19.