Positive electrode material and preparation method thereof, positive electrode plate and battery

Abstract

The invention provides a positive electrode material and a preparation method thereof, a positive electrode plate and a battery. The positive electrode material comprises a lithium-rich oxide, the chemical formula of the lithium-rich oxide is Li1 + xMnyNizMaBr, M is a doped metal element, B comprises an oxygen element, and according to the molar ratio, x is larger than or equal to 0.1 and smaller than or equal to 1.0, y is larger than or equal to 0 and smaller than or equal to 1.0, z is larger than or equal to 0.30 and smaller than or equal to 0.95, a is larger than or equal to 0 and smaller than or equal to 0.1, and r is larger than or equal to 2.0 and smaller than or equal to 2.7. By regulating and controlling the ratio of a lithium metal element to other metal elements in the lithium-rich oxide, material structure design and element doping, the energy barrier of the positive electrode material for de-intercalation and intercalation of lithium ions can be reduced, so that the activation voltage of the battery is low, that is, the positive electrode material can excite more gram capacity at lower voltage, and the battery performance is improved. Therefore, the battery has a wide voltage window.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a positive electrode material and a preparation method thereof, a positive electrode sheet, and a battery. Background Art

[0002] The impact of positive electrode materials on battery performance is crucial. Lithium-rich manganese-based positive electrode materials have both high energy density and cost advantages, thus attracting widespread attention from academia and industry. However, in related technologies, lithium-rich manganese-based positive electrode materials require higher voltages (such as 4.6V) to stimulate a larger gram capacity. At high voltages, the electrode materials and battery systems will experience various side reactions, which in turn lead to unstable electrode materials and low battery system efficiency. Summary of the Invention

[0003] The embodiments of the present application provide a positive electrode material and a preparation method thereof, a positive electrode plate, and a battery, which can improve the technical problem of high activation voltage of the positive electrode material.

[0004] In a first aspect, an embodiment of the present application provides a positive electrode material, comprising a lithium-rich oxide, wherein the chemical formula of the lithium-rich oxide is Li 1+x Mn y Ni z M a B r , wherein M is a doping metal element, B includes an oxygen element, and in molar ratio, 0.1≤x≤1.0, 0≤y≤1.0, 0.30≤z≤0.95, 0≤a≤0.1, and 2.0≤r≤2.7.

[0005] In one embodiment, B further includes nitrogen.

[0006] In one embodiment, based on the total mass of the positive electrode material, the doping amount of the nitrogen element is less than or equal to 1.0 wt %.

[0007] In one embodiment, a carbon coating layer is provided on the surface of the lithium-rich oxide.

[0008] In one embodiment, the carbon in the carbon coating layer comprises graphitized amorphous carbon, and the content of the graphitized amorphous carbon is less than or equal to 10 wt % based on the total mass of the carbon coating layer.

[0009] In one embodiment, based on the total mass of the positive electrode material, the content of the graphitized amorphous carbon is less than or equal to 3 wt %.

[0010] In one embodiment, the doping metal element includes at least one of Fe, Al, Mg, Ti, Nb and Zr.

[0011] In one embodiment, in terms of molar ratio, 0.1 ≤ x ≤ 0.6, 0.18 ≤ y ≤ 0.625, 0.375 ≤ z ≤ 0.74, 0 ≤ a ≤ 0.1, 2.05 ≤ r ≤ 2.35.

[0012] In one embodiment, the positive electrode material is granular, and the D50 particle size of the positive electrode material is 1.0 μm - 15.0 μm.

[0013] In one embodiment, the thickness of the carbon coating layer is 1 nm - 10 nm.

[0014] In a second aspect, an embodiment of the present application provides a method for preparing a positive electrode material for preparing the above positive electrode material, including:

[0015] Providing a first lithium-rich oxide, the chemical formula of the first lithium-rich oxide is Li 1+x Mn y Ni z M a O r , where M is a doped metal element, and in terms of molar ratio, 0.1 ≤ x ≤ 1.0, 0 ≤ y ≤ 1.0, 0.30 ≤ z ≤ 0.95, 0 ≤ a ≤ 0.1, 2.0 ≤ r ≤ 2.7;

[0016] Obtaining a positive electrode material based on the first lithium-rich oxide.

[0017] In one embodiment, the providing of the first lithium-rich oxide includes:

[0018] Adding a nickel source and a manganese source into a solvent to obtain a first mixed solution;

[0019] Adding a precipitating agent into the first mixed solution, and after filtration and drying, obtaining a precursor;

[0020] Performing a first mixing process on a lithium source and the precursor to obtain a first mixture;

[0021] Performing a first calcination process on the first mixture to obtain a first lithium-rich oxide.

[0022] In one embodiment, when preparing the first mixed solution, a doped metal source is further added into the solvent.

[0023] In one embodiment, the obtaining of the positive electrode material based on the first lithium-rich oxide includes:

[0024] Performing a second mixing process on a first coating agent and the first lithium-rich oxide to obtain a second mixture, and the first coating agent is an organic compound containing nitrogen element;

[0025] The second mixture is subjected to a second calcination treatment to obtain a second lithium-rich oxide, and the surface of the second lithium-rich oxide is coated with a carbon coating layer. The chemical formula of the second lithium-rich oxide is Li 1+x Mn y Ni z M a B r , where M is a doped metal element, B includes O and N, and in terms of molar ratio, 0.1 ≤ x ≤ 1.0, 0 ≤ y ≤ 1.0, 0.30 ≤ z ≤ 0.95, 0 ≤ a ≤ 0.1, 2.0 ≤ r ≤ 2.7.

[0026] In one embodiment, when preparing the second mixture, a second coating agent is further added to the first lithium-rich oxide, and the carbonization temperature of the second coating agent is lower than that of the first coating agent.

[0027] In one embodiment, the first coating agent includes at least one of polyaniline and melamine.

[0028] In one embodiment, the second coating agent includes at least one of glucose, polyethylene glycol, sucrose, polyaniline, and polypyrrole.

[0029] In one embodiment, in the second mixture, in terms of mass ratio, the first coating agent: the second coating agent: the first lithium-rich oxide is (0.1 - 2.0): (3.0 - 6.0): (92 - 94).

[0030] In one embodiment, the temperature of the second calcination treatment is 600°C to 800°C, and the time is 6h to 12h.

[0031] In one embodiment, the nickel source includes at least one of nickel sulfate, nickel nitrate, nickel acetate, nickel carbonate, and nickel chloride.

[0032] In one embodiment, the manganese source includes at least one of manganese sulfate, manganese nitrate, manganese carbonate, manganese acetate, manganese tetroxide, and manganese dioxide.

[0033] In one embodiment, the doped metal source includes at least one of iron salts, aluminum salts, magnesium salts, titanium salts, niobium salts, and zirconium salts.

[0034] In one embodiment, the solvent includes water.

[0035] In one embodiment, in the first mixed solution, the molar ratio of manganese element, nickel element, and doped metal element is (0 - 1.0): (0.3 - 0.95): (0 - 0.1).

[0036] In one embodiment, in the first mixed solution, the concentration of manganese element is 0.1 mol / L to 0.65 mol / L, the concentration of nickel element is 0.3 mol / L to 1.5 mol / L, and the concentration of doped metal element is 0.01 mol / L to 0.1 mol / L.

[0037] In one embodiment, the precipitating agent includes at least one of sodium hydroxide and potassium hydroxide.

[0038] In one embodiment, after adding the precipitating agent, the concentration of the precipitating agent in the first mixed solution is 0.1 mol / L to 2.0 mol / L.

[0039] In one embodiment, after adding the precipitating agent, the pH of the first mixed solution is 8 to 11.

[0040] In one embodiment, the time of the precipitation reaction is 3 h to 10 h.

[0041] In one embodiment, the lithium source includes at least one of lithium hydroxide, lithium carbonate and lithium oxide.

[0042] In one embodiment, in the first mixture, the molar ratio of lithium element in the lithium source to nickel element in the precursor is 1.2 to 4.0.

[0043] In one embodiment, the first mixing treatment is a grinding treatment.

[0044] In one embodiment, the time of the first mixing treatment is 30 min to 180 min.

[0045] In one embodiment, the temperature of the first calcination treatment is 600 °C to 800 °C, and the time is 3 to 8 h.

[0046] In a third aspect, an embodiment of the present application provides a positive electrode plate, including a positive electrode current collector and a positive electrode film layer combined with the positive electrode current collector, and the positive electrode film layer includes the above positive electrode material or the positive electrode material prepared by the above positive electrode material preparation method.

[0047] In a fourth aspect, an embodiment of the present application provides a battery, including the above positive electrode plate.

[0048] Advantageous effects of the embodiments of the present application:

[0049] In the embodiments of the present application, the positive electrode material includes a lithium-rich oxide. By adjusting the ratio of lithium metal elements to other metal elements in the lithium-rich oxide, the energy barrier for lithium ion insertion and extraction in the positive electrode material can be reduced, that is, the potential of the positive electrode material is reduced. In this way, when the positive electrode material is applied to a battery, the formation activation voltage of the battery is low, that is, the positive electrode material can excite a relatively large specific capacity at a lower voltage (for example, 4.2V), thereby enabling the battery to have a wider voltage window. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application. For those skilled in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0051] Figure 1 is a scanning electron microscope image of the positive electrode material provided in Embodiment 1 of the present application;

[0052] Figure 2 is an X-ray diffraction pattern of the positive electrode material provided in Embodiment 1 of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0053] The following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, rather than all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative efforts belong to the scope of protection of the present application. In addition, it should be understood that the specific embodiments described herein are only used to illustrate and explain the present application, and are not used to limit the present application.

[0054] In the present application, unless otherwise stated, the orientation terms such as "upper" and "lower" usually refer to the upper and lower in the actual use or working state of the device, specifically the plane direction in the drawings; and "inner" and "outer" refer to the outline of the device. In addition, in the description of the present application, the term "comprising" means "including but not limited to". The terms first, second, third, etc. are only used as labels and do not impose numerical requirements or establish an order.

[0055] In the present application, "and / or" describes the association relationship of associated objects, indicating that three relationships can exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. Wherein A and B can be singular or plural.

[0056] In the present application, "at least one" means one or more, and "a plurality" means two or more. "One or several", "at least one (item) below" or similar expressions refer to any combination of these items, including any combination of single items or plural items. For example, "at least one (item) of a, b, or c", or "at least one (item) of a, b, and c" can both represent: a, b, c, a - b (i.e., a and b), a - c, b - c, or a - b - c, where a, b, and c can each be single or multiple.

[0057] Various embodiments of the present application may exist in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity and should not be construed as a rigid limitation on the scope of the present application; therefore, it should be considered that the described range description has specifically disclosed all possible sub - ranges and single values within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub - ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, which applies regardless of the range. Additionally, whenever a numerical range is indicated herein, it means including any cited number (fraction or integer) within the indicated range.

[0058] In a first aspect, an embodiment of the present application provides a positive electrode material, which includes a lithium - rich oxide. The chemical formula of the lithium - rich oxide is Li 1+x Mn y Ni z M a B r , where M is a doped metal element, B includes oxygen element, and in terms of molar ratio, 0.1 ≤ x ≤ 1.0, 0 ≤ y ≤ 1.0, 0.30 ≤ z ≤ 0.95, 0 ≤ a ≤ 0.1, 2.0 ≤ r ≤ 2.7.

[0059] It can be understood that when a = 0, that is, the lithium - rich oxide does not contain a doped metal element; when a > 0, the lithium - rich oxide contains a doped metal element. As an example, a is 0, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, or 0.1.

[0060] The positive electrode material provided by the embodiment of the present application includes a lithium - rich oxide. By regulating the ratio of lithium metal element to other metal elements in the lithium - rich oxide, the energy barrier for lithium - ion de - intercalation and intercalation of the positive electrode material can be reduced, that is, the potential of the positive electrode material is reduced. In this way, when the positive electrode material is applied to a battery, the formation activation voltage of the battery is low, that is, the positive electrode material can excite more gram - capacities at a lower voltage (for example, 4.2V), so that the battery has a wider voltage window.

[0061] In some embodiments, the lithium-rich oxide contains a doped metal element, i.e., a > 0. By doping other metals except Li, Mn, and Ni in the lithium-rich oxide, the potential of the cathode material can be further reduced, thereby reducing the formation activation voltage of the battery. Optionally, the doped metal element includes at least one of Fe, Al, Mg, Ti, Nb, and Zr. Doping the above metals in the lithium-rich oxide can effectively reduce the potential of the cathode material.

[0062] In some embodiments, in terms of molar ratio, 0.1 ≤ x ≤ 0.6, 0.18 ≤ y ≤ 0.625, 0.375 ≤ z ≤ 0.74, 0 ≤ a ≤ 0.1, 2.05 ≤ r ≤ 2.35. Within this ratio range, different metal elements can cooperate synergistically to reduce the potential of the cathode material. For example, within this ratio range, the specific capacity of the cathode material at 4.2 V can reach 160 mAh / g or more. As an example, x is 0.1, 0.2, 0.3, 0.4, 0.5, or 0.6; y is 0.18, 0.20, 0.30, 0.40, 0.50, 0.60, or 0.625; z is 0.375, 0.40, 0.50, 0.60, 0.70, or 0.74; a is 0, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, or 0.1; r is 2.05, 2.15, 2.25, or 2.35.

[0063] In some embodiments, B further includes nitrogen, that is, nitrogen is also doped in the lithium-rich oxide. Since the lithium-rich oxide will undergo lattice expansion or contraction during the process of intercalating and deintercalating lithium ions, resulting in changes and collapses in the structure of the lithium-rich oxide, and doping nitrogen in the lithium-rich oxide, nitrogen doping belongs to anion doping, which can improve the structural stability of the lithium-rich oxide during the process of intercalating and deintercalating lithium ions.

[0064] In some embodiments, based on the weight of the cathode material, the doping amount of nitrogen is less than or equal to 1.0 wt%. In other words, the mass content of nitrogen in the cathode material is less than or equal to 1.0 wt%. Generally, the doping amount of nitrogen in the cathode material should not be too large, otherwise it will affect the synthesis stability during the preparation of the cathode material, thereby increasing the preparation difficulty of the cathode material. Especially in the case of a higher doping concentration, the doping process needs to be greatly adjusted, which instead increases the production cost of the cathode material. As an example, in the cathode material, the doping amount of nitrogen is 0.1 wt%, 0.2 wt%, 0.4 wt%, 0.6 wt%, 0.8 wt%, or 1.0 wt%.

[0065] In some embodiments, a carbon coating layer is provided on the surface of the lithium-rich oxide. The interfacial reactions between the lithium-rich oxide and the electrolyte mainly include lithium-ion deintercalation and side reactions. Since the rate of lithium-ion transport in the electrolyte is greater than the rate of lithium-ion transport inside the lithium-rich oxide, lithium ions in the electrolyte are likely to accumulate on the surface of the lithium-rich oxide. By providing a carbon coating layer, the carbon coating layer is more easily wetted by the electrolyte than the lithium-rich oxide, so that the carbon coating layer forms an intermediate transition region, and then a gradient change in lithium-ion distribution from the electrolyte to the coating layer and then to the lithium-rich oxide is formed. Instead, this can assist in lithium-ion deintercalation, reduce the potential of the positive electrode material, and improve the stability and cycling performance of the positive electrode material. Optionally, when nitrogen elements are doped in the lithium-rich oxide, nitrogen elements are also doped in the carbon coating layer, so that nitrogen doping can be carried out synchronously when the carbon coating layer is coated on the surface of the lithium-rich oxide, reducing the preparation process of the positive electrode material and lowering the production cost.

[0066] In some embodiments, the carbon in the carbon coating layer includes graphitized amorphous carbon. Based on the total mass of carbon in the carbon coating layer, the content of graphitized amorphous carbon is less than or equal to 10 wt%. Usually, the carbon in the carbon coating layer is mainly amorphous carbon. Amorphous carbon has characteristics such as a large interlayer spacing and a disordered microcrystalline structure. By graphitizing part of the amorphous carbon, this part of the amorphous carbon changes from a disordered amorphous state to an ordered graphite structure, which can promote lithium-ion deintercalation, reduce the potential drop of the positive electrode material, thereby reducing the formation activation voltage of the battery and reducing polarization. Usually, the graphitized amorphous carbon can be obtained by gradually transforming the amorphous carbon from a disordered structure to a more ordered graphite structure through high-temperature treatment. If the content of graphitized amorphous carbon in the carbon coating layer is too high, it will lead to an increase in the production cost of the positive electrode material. By controlling the content of graphitized amorphous carbon in the carbon coating layer to be less than or equal to 10 wt%, the cost of the positive electrode material can be controlled under the condition of ensuring effective lithium-ion deintercalation. As an example, based on the total mass of carbon in the carbon coating layer, the content of graphitized amorphous carbon is 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt% or 10 wt%.

[0067] In some embodiments, based on the total mass of the positive electrode material, the content of graphitized amorphous carbon is less than or equal to 3 wt%. As an example, based on the total mass of the positive electrode material, the content of graphitized amorphous carbon is 0.5 wt%, 1 wt%, 1.5 wt%, 2 wt%, 2.5 wt% or 3 wt%.

[0068] In some embodiments, the thickness of the carbon coating layer is 1 nm - 10 nm. The carbon coating layer can make it easier for lithium ions to be deintercalated and intercalated, thereby reducing the potential of the cathode material. However, the carbon coating layer should not be too thick, otherwise it will cause energy loss and reduce the battery performance. As an example, the thickness of the carbon coating layer is 1 nm, 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm or 10 nm.

[0069] In some embodiments, the cathode material is granular, and the D50 particle size of the cathode material is 1.0 μm - 15.0 μm. It can be understood that the larger the particle size of the cathode material, the greater the difficulty for lithium ions to be deintercalated and intercalated on the cathode material, and the higher the formation activation voltage of the battery; by reducing the particle size of the cathode material, the energy barrier for lithium ion deintercalation in the cathode material can be reduced, thereby reducing the potential of the cathode material; however, the particle size of the cathode material cannot be too small, otherwise the side reactions on the surface of the cathode material will be aggravated, which will instead affect the battery performance. As an example, the D50 particle size of the cathode material is 1.0 μm, 2.0 μm, 3.0 μm, 4.0 μm, 5.0 μm, 6.0 μm, 7.0 μm, 8.0 μm, 9.0 μm, 10.0 μm, 11.0 μm, 12.0 μm, 13.0 μm, 14.0 μm or 15.0 μm.

[0070] In a second aspect, an embodiment of the present application provides a method for preparing a cathode material for preparing the above-mentioned cathode material. The method for preparing the cathode material includes:

[0071] S10. Provide a first lithium-rich oxide, and the chemical formula of the first lithium-rich oxide is Li 1+x Mn y Ni z M a O r , where M is a doped metal element. In terms of molar ratio, 0.1 ≤ x ≤ 1.0, 0 ≤ y ≤ 1.0, 0.30 ≤ z ≤ 0.95, 0 ≤ a ≤ 0.1, 2.0 ≤ r ≤ 2.7;

[0072] S20. Obtain the cathode material based on the first lithium-rich oxide.

[0073] The method for preparing the cathode material provided by the embodiment of the present application is simple and easy to operate.

[0074] In some embodiments, obtaining the cathode material based on the first lithium-rich oxide means directly using the first lithium-rich oxide as the cathode material. It can be understood that the lithium-rich oxide includes the first lithium-rich oxide. The first lithium-rich oxide is the case where X in the lithium-rich oxide only includes oxygen.

[0075] In some embodiments, step S10: providing the first lithium-rich oxide includes:

[0076] S11. Add a nickel source and a manganese source to a solvent to obtain a first mixed solution;

[0077] S12. Add a precipitating agent to the first mixed solution, and after filtration and drying treatments, obtain a precursor;

[0078] S13. Perform a first mixing treatment on a lithium source and the precursor to obtain a first mixture;

[0079] S14. Perform a first calcination treatment on the first mixture to obtain a first lithium-rich oxide.

[0080] In some embodiments, when preparing the first mixed solution, a doping metal source is further added to the solvent. That is, step S11 is: add a nickel source, a manganese source, and a doping metal source to the solvent to obtain a first mixed solution. It can be understood that in this case, the first mixed solution prepared contains a nickel source, a manganese source, and a doping metal source, and thus the first lithium-rich oxide prepared contains a doping metal element, that is, a > 0. Of course, in other embodiments, the doping metal source may not be added to the solvent, so that the first mixed solution prepared contains a nickel source and a manganese source, and thus the first lithium-rich oxide prepared does not contain a doping metal element, that is, a = 0.

[0081] The following takes the first mixed solution containing a nickel source, a manganese source, and a doping metal source as an example for illustration.

[0082] In some embodiments, in step S11: the nickel source may include at least one of nickel sulfate, nickel nitrate, nickel acetate, nickel carbonate, and nickel chloride; the manganese source may include at least one of manganese sulfate, manganese nitrate, manganese carbonate, manganese acetate, manganese tetroxide, and manganese dioxide; the doping metal source may include at least one of iron salts, aluminum salts, magnesium salts, titanium salts, niobium salts, and zirconium salts.

[0083] In some embodiments, in step S11: the solvent includes water. In this case, the nickel source, the manganese source, and the doping metal source can generally be selected as nickel salts, manganese salts, and doping metal salts that are easily soluble in water. Dissolving the nickel salts, manganese salts, and doping metal salts in water can obtain the first mixed solution. In the first mixed solution, nickel elements, manganese elements, and doping metal elements are respectively distributed in water in the form of manganese ions, nickel ions, and doping metal ions.

[0084] In some embodiments, in step S11: in the case where at least one of the nickel source, the manganese source, and the doping metal source contains a metal oxide that is insoluble in water, the solvent may further contain an acid that is soluble in water, and the acid reacts with the metal oxide so that the metal elements can be distributed in water in ionic form.

[0085] In some embodiments, in step S11: In the first mixed solution, the molar ratio of manganese element, nickel element and doped metal element is (0-1.0):(0.3-0.95):(0-0.1). Generally, in the first mixed solution, the molar ratio of manganese element, nickel element and doped metal element will affect the composition of the lithium-rich oxide in the prepared cathode material. By controlling the molar ratio of manganese element, nickel element and doped metal element in the first mixed solution, the potential of the cathode material can be adjusted. As an example, the molar ratio of manganese element, nickel element and doped metal element is 0.5:0.5:0, 0.4:0.5:0.08, 0.3:0.7:0.07 or 0.2:0.7:0.09.

[0086] In some embodiments, in step S11: In the first mixed solution, the concentration of manganese element is 0.1 mol / L to 0.65 mol / L, the concentration of nickel element is 0.3 mol / L to 1.5 mol / L, and the concentration of doped metal element is 0.01 mol / L to 0.1 mol / L. By appropriately increasing the concentration of nickel element in the first mixed solution, the content of nickel element in the lithium-rich oxide can be increased. The increase in the content of nickel element is beneficial to reducing the potential of the cathode material, thereby reducing the activation voltage of the battery. As an example, in the first mixed solution, the concentration of manganese element is 0.1 mol / L, 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, 0.6 mol / L or 0.65 mol / L, the concentration of nickel element is 0.3 mol / L, 0.5 mol / L, 0.7 mol / L, 0.9 mol / L, 1.1 mol / L, 1.3 mol / L or 1.5 mol / L, and the concentration of doped metal element is 0.01 mol / L, 0.02 mol / L, 0.04 mol / L, 0.06 mol / L, 0.08 mol / L or 0.1 mol / .

[0087] In some embodiments, in step S12: The precipitating agent includes at least one of sodium hydroxide and potassium hydroxide. The above-mentioned precipitating agents all contain hydroxide ions. After adding the precipitating agent to the first mixed solution, metal ions (such as nickel ions, manganese ions, and doped metal ions, etc.) in the first mixed solution can react with the hydroxide ions to form precipitates. By filtering and drying the precipitates, the precursor can be obtained. Optionally, after adding the precipitating agent, the concentration of the precipitating agent in the first mixed solution is 0.1 mol / L to 2.0 mol / L. Here, the concentration of the precipitating agent refers to the designed concentration of the precipitating agent in the first mixed solution, that is, the theoretical concentration of the precipitating agent in the first mixed solution before the precipitation reaction occurs. As an example, the concentration of the precipitating agent is 0.1 mol / L, 0.2 mol / L, 0.4 mol / L, 0.6 mol / L, 0.8 mol / L, 1.0 mol / L, 1.2 mol / L, 1.4 mol / L, 1.6 mol / L, 1.8 mol / L or 2.0 mol / L.

[0088] In some embodiments, in step S12: After adding the precipitating agent, since the precipitating agent contains hydroxide ions, the first mixed solution is alkaline. Optionally, the pH of the first mixed solution is 8 to 11. As an example, the pH of the first mixed solution is 8, 8.5, 9, 9.5, 10, 10.5 or 11.

[0089] In some embodiments, in step S12: The precipitation reaction time is 3 h to 10 h. Here, the precipitation reaction time refers to the duration from when the precipitating agent is added to the first mixed solution until the precipitates formed by the reaction are filtered. By controlling the precipitation reaction time within the above range, the metal ions in the first mixed solution can react fully with the precipitating agent while ensuring production efficiency.

[0090] In some embodiments, in step S13: The lithium source includes at least one of lithium hydroxide, lithium carbonate, and lithium oxide. In step S13, the first mixing process of the lithium source and the precursor specifically refers to grinding the lithium source and the precursor. During the grinding process, the lithium source and the precursor are fully mixed to obtain the first mixture. Optionally, the time for the first mixing process is 30 min to 180 min, such as 30 min, 60 min, 90 min, 120 min, 150 min or 180 min.

[0091] In some embodiments, in step S13: in the first mixture, the molar ratio of lithium element in the lithium source to nickel element in the precursor is 1.2 to 4.0. By controlling the molar ratio of lithium element to nickel element during the preparation process, the obtained cathode material not only has a low potential but also a large lithium deintercalation amount, thereby improving the energy density of the battery. As an example, the molar ratio of lithium element in the lithium source to nickel element in the precursor is 1.2, 1.4, 1.5, 1.6, 1.7, 1.8, 2.0, 2.2, 2.4, 2.6, 2.8, 3.0, 3.2, 3.4, 3.6, 3.8 or 4.0.

[0092] In some embodiments, in step S14: the temperature of the first calcination treatment is 600 °C to 800 °C, and the time is 3 h to 8 h. During the first calcination treatment, the lithium source reacts with the precursor to obtain the first lithium-rich oxide. As an example, the temperature of the first calcination treatment is 600 °C, 650 °C, 700 °C, 750 °C or 800 °C; the time of the first calcination treatment is 3 h, 4 h, 5 h, 6 h, 7 h or 8 h. Optionally, the calcination atmosphere of the first calcination treatment is an air atmosphere.

[0093] In some embodiments, in step S14: after the first calcination treatment, the first lithium-rich oxide is obtained, and the chemical formula of the lithium-rich oxide is Li 1+x Mn y Ni z M a O r , where M is a doped metal element, and in terms of molar ratio, 0.1 ≤ x ≤ 1.0, 0 ≤ y ≤ 1.0, 0.30 ≤ z ≤ 0.95, 0 ≤ a ≤ 0.1, 2.0 ≤ r ≤ 2.7.

[0094] In some embodiments, step S20: obtaining the cathode material based on the first lithium-rich oxide includes:

[0095] S21. Performing a second mixing treatment on the first coating agent and the first lithium-rich oxide to obtain a second mixture, and the first coating agent is an organic compound containing nitrogen element;

[0096] S22. Performing a second calcination treatment on the second mixture to obtain a second lithium-rich oxide, and a carbon coating layer is coated on the surface of the second lithium-rich oxide. The chemical formula of the second lithium-rich oxide is Li 1+x Mn y Ni z M a B r , where M is a doped metal element, B includes O and N, and in terms of molar ratio, 0.1 ≤ x ≤ 1.0, 0 ≤ y ≤ 1.0, 0.30 ≤ z ≤ 0.95, 0 ≤ a ≤ 0.1, 2.0 ≤ r ≤ 2.7.

[0097] By mixing an organic compound containing nitrogen with a first lithium-rich oxide and performing high-temperature calcination, during this process, the organic compound containing nitrogen undergoes thermal decomposition, and the nitrogen element penetrates into the first lithium-rich oxide under the action of high temperature, thereby realizing doping of the first lithium-rich oxide and obtaining a second lithium-rich oxide, and the carbon element remains and forms a carbon coating layer covering the surface of the second lithium-rich oxide.

[0098] It can be understood that the lithium-rich oxide includes the second lithium-rich oxide. The second lithium-rich oxide is the case where the lithium-rich oxide includes B, O, and N.

[0099] In some embodiments, in step S21: the first coating agent includes at least one of polyaniline and melamine.

[0100] In some embodiments, in step S21: when preparing the second mixture, a second coating agent is further added to the first lithium-rich oxide, wherein the carbonization temperature of the second coating agent is lower than that of the first coating agent. That is to say, step S21 is: performing a second mixing process on the first coating agent, the second coating agent, and the first lithium-rich oxide to obtain a second mixture. The carbonization temperature of the second coating agent is lower than that of the first coating agent, that is to say, the heat resistance of the second coating agent is lower than that of the first coating agent. In this way, after the second mixture undergoes the second calcination process, the first coating agent is more likely to form residual groups, while the second coating agent is more likely to be carbonized to obtain graphitized amorphous carbon, and the cooperation of the first coating agent and the second coating agent can also make the prepared carbon coating layer have a three-dimensional structure, further improving the insertion and extraction of lithium ions.

[0101] Here, the second coating agent can be a nitrogen-containing organic compound or a non-nitrogen-containing organic compound. In some embodiments, in step S21: the second coating agent includes at least one of glucose, polyethylene glycol (PEG), sucrose, polyaniline, and polypyrrole.

[0102] In some embodiments, in step S21: in the second mixture, by mass ratio, the first coating agent: the second coating agent: the first lithium-rich oxide is (0.1 - 2.0):(3.0 - 6.0):(92 - 94). At this ratio, the potential of the prepared cathode material can be made lower.

[0103] In some embodiments, in step S22: the temperature of the second calcination process is 600°C to 800°C, and the time is 6h to 12h. As an example, the temperature of the second calcination process is 600°C, 650°C, 700°C, 750°C, or 800°C; the time of the second calcination process is 6h, 7h, 8h, 9h, 10h, 11h, or 12h. Optionally, the calcination atmosphere of the second calcination process is an inert atmosphere.

[0104] In a third aspect, an embodiment of the present application provides a positive electrode sheet, which includes a positive electrode current collector and a positive electrode film layer combined with the positive electrode current collector. The positive electrode film layer includes the above-mentioned positive electrode material or the positive electrode material prepared by the above-mentioned preparation method of the positive electrode material.

[0105] In some embodiments, the positive electrode current collector is aluminum foil. As an example, the positive electrode film layer is provided on one side surface or both side surfaces of the aluminum foil.

[0106] In some embodiments, the positive electrode film layer further includes a conductive agent and a binder. As an example, the conductive agent includes at least one of conductive carbon black (SP), carbon nanotubes (CNT), and vapor-grown carbon fibers (VGCF). As an example, the binder includes at least one of polyacrylic acid (PAA), polyvinylidene fluoride (PVDF), and polyvinyl alcohol (PVA).

[0107] In some embodiments, the positive electrode film layer includes 95wt% - 97wt%, the conductive agent is 1wt% - 2wt%, and the binder is 1wt% - 3wt%.

[0108] In a fourth aspect, an embodiment of the present application provides a battery, which includes the above-mentioned positive electrode sheet.

[0109] In some embodiments, the battery further includes a negative electrode sheet and a separator. The positive electrode sheet, the negative electrode sheet, and the separator are stacked, and the separator is located between the positive electrode sheet and the negative electrode sheet.

[0110] In some embodiments, the battery may also include a negative electrode sheet and a solid electrolyte membrane. The positive electrode sheet, the negative electrode sheet, and the solid electrolyte membrane are stacked, and the solid electrolyte membrane is located between the positive electrode sheet and the negative electrode sheet.

[0111] In some embodiments, the negative electrode sheet includes a negative electrode current collector and a negative electrode film layer combined with the negative electrode current collector. The negative electrode film layer includes at least one of graphite, silicon, silicon oxide, and silicon carbon.

[0112] In some embodiments, the battery further includes a housing, and an electrolyte is loaded in the housing. The positive electrode sheet and the negative electrode sheet are also located in the housing, and the electrolyte wets the positive electrode sheet and the negative electrode sheet.

[0113] In some embodiments, the battery is a lithium-ion battery.

[0114] The following is described in conjunction with specific embodiments.

[0115] Example 1

[0116] 1.1. Preparation of the positive electrode material:

[0117] S1. Dissolve soluble Ni salt nickel sulfate and Mn salt manganese sulfate in water to obtain a first mixed solution. In the first mixed solution, the concentration of Ni element is 0.475 mol / L, and the concentration of Mn element is 0.525 mol / L;

[0118] S2. Add precipitant sodium hydroxide to the first mixed solution, filter and dry after a precipitation reaction for 5 h to obtain a precursor;

[0119] S3. Grind and mix lithium salt lithium hydroxide and the precursor according to the molar ratio of lithium element to Ni element = 1.15:0.475, and dry to obtain a first mixed material;

[0120] S4. Perform low-temperature roasting (i.e., the first roasting treatment) on the first mixed material. The roasting temperature is 700 °C and the time is 5 h to obtain a first lithium-rich oxide;

[0121] S5. Wet-mix the first lithium-rich oxide, the first coating agent polyaniline, and the second coating agent glucose according to the mass ratio of 93:0.5:4 to obtain a second mixed material;

[0122] S6. Perform drying and roasting (i.e., the second roasting treatment) on the second mixed material. The roasting temperature is 700 °C and the time is 8 h to obtain a cathode material.

[0123] 1.2. Prepare a cathode plate: Premix the above cathode material, conductive agent SP, and binder PVDF according to a mass ratio of 96:2.5:1.5, then stir in a stirring tank for uniform mixing, add solvent N-methylpyrrolidone (NMP) to prepare a cathode slurry, control the discharge viscosity and solid content of the cathode slurry, and then evenly coat the cathode slurry on aluminum foil, dry, cold press, and die-cut and slit to prepare a cathode plate.

[0124] 1.3. Prepare a battery: Assemble the above cathode plate with an anode plate (the anode slurry formula is: graphite:SP:CMC:SBR = 96.7:0.6:1.2:1.5 (mass ratio), and the current collector is copper foil), a separator (PE separator), and an electrolyte (the electrolyte is 1 M LiPF6 (EC:DEC:DMC = 1:1:1, volume ratio)) into a battery.

[0125] Example 2

[0126] The difference from Example 1 is:

[0127] 1.1. Prepare a cathode material:

[0128] S1. Dissolve soluble Ni salt nickel sulfate and Mn salt manganese sulfate in water to obtain a first mixed solution. In the first mixed solution, the concentration of Ni element is 0.5 mol / L, and the concentration of Mn element is 0.5 mol / L;

[0129] S2. Add the precipitant sodium hydroxide to the first mixed solution. After a precipitation reaction for 5 h, filter and dry to obtain the precursor.

[0130] S3. Grind and mix lithium hydroxide (lithium salt) and the precursor in a molar ratio of lithium element to Ni element = 1.10:0.5, and then dry to obtain the first mixture.

[0131] S4. Perform low-temperature calcination (i.e., the first calcination treatment) on the first mixture. The calcination temperature is 700 °C and the time is 5 h to obtain the first lithium-rich oxide.

[0132] S5. Wet-mix the first lithium-rich oxide, the first coating agent polyaniline, and the second coating agent glucose in a mass ratio of 93:0.5:4 to obtain the second mixture.

[0133] S6. Perform drying and calcination (i.e., the second calcination treatment) on the second mixture. The calcination temperature is 700 °C and the time is 8 h to obtain the cathode material.

[0134] Others are the same as in Example 1.

[0135] Example 3

[0136] The difference from Example 1 is as follows:

[0137] 1.1. Preparation of the cathode material:

[0138] S1. Dissolve soluble nickel salt nickel sulfate and manganese salt manganese sulfate in water to obtain the first mixed solution. In the first mixed solution, the concentration of Ni element is 0.45 mol / L and the concentration of Mn element is 0.55 mol / L.

[0139] S2. Add the precipitant sodium hydroxide to the first mixed solution. After a precipitation reaction for 5 h, filter and dry to obtain the precursor.

[0140] S3. Grind and mix lithium hydroxide (lithium salt) and the precursor in a molar ratio of lithium element to Ni element = 1.20:0.45, and then dry to obtain the first mixture.

[0141] S4. Perform low-temperature calcination (i.e., the first calcination treatment) on the first mixture. The calcination temperature is 700 °C and the time is 5 h to obtain the first lithium-rich oxide.

[0142] S5. Wet-mix the first lithium-rich oxide, the first coating agent polyaniline, and the second coating agent glucose in a mass ratio of 93:0.5:4 to obtain the second mixture.

[0143] S6. Dry roast the second mixture (i.e., the second roasting treatment) at a temperature of 700 °C for 8 h to obtain the cathode material.

[0144] Others are the same as in Example 1.

[0145] Example 4

[0146] The difference from Example 1 is as follows:

[0147] 1.1. Prepare the cathode material:

[0148] S1. Dissolve the soluble Ni salt nickel sulfate and Mn salt manganese sulfate in water to obtain a first mixed solution. In the first mixed solution, the concentration of Ni element is 0.375 mol / L, and the concentration of Mn element is 0.625 mol / L.

[0149] S2. Add the precipitant sodium hydroxide to the first mixed solution, filter and dry after a precipitation reaction for 5 h to obtain the precursor.

[0150] S3. Grind and mix the lithium salt lithium hydroxide and the precursor in a molar ratio of lithium element to Ni element = 1.45:0.375, and dry to obtain the first mixture.

[0151] S4. Perform low-temperature roasting (i.e., the first roasting treatment) on the first mixture at a temperature of 700 °C for 5 h to obtain the first lithium-rich oxide.

[0152] S5. Wet-mix the first lithium-rich oxide, the first coating agent polyaniline, and the second coating agent glucose in a mass ratio of 93:0.5:4 to obtain the second mixture.

[0153] S6. Dry roast the second mixture (i.e., the second roasting treatment) at a temperature of 700 °C for 8 h to obtain the cathode material.

[0154] Others are the same as in Example 1.

[0155] Example 5

[0156] The difference from Example 1 is as follows:

[0157] 1.1. Prepare the cathode material:

[0158] S1. Dissolve the soluble Ni salt nickel sulfate, Mn salt manganese sulfate, and doped metal salt aluminum sulfate in water to obtain a first mixed solution. In the first mixed solution, the concentration of Ni element is 0.54 mol / L, the concentration of Mn element is 0.38 mol / L, and the concentration of Al element is 0.08 mol / L.

[0159] S2. Add precipitant sodium hydroxide to the first mixed solution, filter and dry after a precipitation reaction for 5 h to obtain a precursor;

[0160] S3. Grind and mix lithium hydroxide as the lithium salt and the precursor in a molar ratio of lithium element to Ni element = 1.60:0.54, and dry to obtain a first mixture;

[0161] S4. Perform low-temperature calcination (i.e., the first calcination treatment) on the first mixture at a calcination temperature of 700 °C for 5 h to obtain a first lithium-rich oxide;

[0162] S5. Wet and mix the first lithium-rich oxide, the first coating agent polyaniline, and the second coating agent glucose in a mass ratio of 93:0.5:4 to obtain a second mixture;

[0163] S6. Perform drying and calcination (i.e., the second calcination treatment) on the second mixture at a calcination temperature of 700 °C for 8 h to obtain a cathode material.

[0164] Others are the same as in Example 1.

[0165] Example 6

[0166] The difference from Example 1 is as follows:

[0167] 1.1. Preparation of cathode material:

[0168] S1. Dissolve nickel sulfate as the soluble Ni salt, manganese sulfate as the Mn salt, and aluminum sulfate as the doped metal salt in water to obtain a first mixed solution. In the first mixed solution, the concentration of Ni element is 0.54 mol / L, the concentration of Mn element is 0.36 mol / L, and the concentration of Al element is 0.1 mol / L;

[0169] S2. Add precipitant sodium hydroxide to the first mixed solution, filter and dry after a precipitation reaction for 5 h to obtain a precursor;

[0170] S3. Grind and mix lithium hydroxide as the lithium salt and the precursor in a molar ratio of lithium element to Ni element = 1.35:0.54, and dry to obtain a first mixture;

[0171] S4. Perform low-temperature calcination (i.e., the first calcination treatment) on the first mixture at a calcination temperature of 700 °C for 5 h to obtain a first lithium-rich oxide;

[0172] S5. Wet and mix the first lithium-rich oxide, the first coating agent polyaniline, and the second coating agent glucose in a mass ratio of 93:0.5:4 to obtain a second mixture;

[0173] S6. Dry roast the second mixture (i.e., the second roasting treatment) at a temperature of 700 °C for 8 h to obtain the cathode material.

[0174] Others are the same as in Example 1.

[0175] Example 7

[0176] The difference from Example 1 is as follows:

[0177] 1.1. Prepare the cathode material:

[0178] S1. Dissolve soluble nickel salt nickel sulfate, manganese salt manganese sulfate, and doping metal salt aluminum sulfate in water to obtain a first mixed solution. In the first mixed solution, the concentration of Ni element is 0.73 mol / L, the concentration of Mn element is 0.185 mol / L, and the concentration of Al element is 0.085 mol / L.

[0179] S2. Add precipitant sodium hydroxide to the first mixed solution, filter and dry after a precipitation reaction for 5 h to obtain the precursor.

[0180] S3. Grind and mix lithium salt lithium hydroxide and the precursor in a molar ratio of lithium element to Ni element = 1.15:0.73, and dry to obtain the first mixture.

[0181] S4. Perform low-temperature roasting on the first mixture (i.e., the first roasting treatment) at a temperature of 700 °C for 5 h to obtain the first lithium-rich oxide.

[0182] S5. Wet-mix the first lithium-rich oxide, the first coating agent polyaniline, and the second coating agent glucose in a mass ratio of 93:0.5:4 to obtain the second mixture.

[0183] S6. Dry roast the second mixture (i.e., the second roasting treatment) at a temperature of 700 °C for 8 h to obtain the cathode material.

[0184] Others are the same as in Example 1.

[0185] Example 8

[0186] The difference from Example 1 is as follows:

[0187] 1.1. Prepare the cathode material:

[0188] S1. Dissolve soluble nickel salt nickel sulfate, manganese salt manganese sulfate, and doping metal salt zirconium sulfate in water to obtain a first mixed solution. In the first mixed solution, the concentration of Ni element is 0.74 mol / L, the concentration of Mn element is 0.18 mol / L, and the concentration of Zr element is 0.08 mol / L.

[0189] S2. Add the precipitant sodium hydroxide to the first mixed solution. After a precipitation reaction for 5 h, filter and dry to obtain a precursor.

[0190] S3. Grind and mix lithium hydroxide (lithium salt) and the precursor in a molar ratio of lithium element to Ni element = 1.20:0.74, and then dry to obtain a first mixture.

[0191] S4. Perform low-temperature roasting (i.e., the first roasting treatment) on the first mixture at a roasting temperature of 700 °C for 5 h to obtain a first lithium-rich oxide.

[0192] S5. Wet-mix the first lithium-rich oxide, the first coating agent polyaniline, and the second coating agent glucose in a mass ratio of 93:0.5:4 to obtain a second mixture.

[0193] S6. Perform drying and roasting (i.e., the second roasting treatment) on the second mixture at a roasting temperature of 700 °C for 8 h to obtain a cathode material.

[0194] Others are the same as in Example 1.

[0195] Example 9

[0196] The difference from Example 1 is as follows:

[0197] 1.1. Preparation of cathode material:

[0198] S1. Dissolve soluble nickel salt nickel sulfate, manganese salt manganese sulfate, and doped metal salt magnesium sulfate magnesium sulfate in water to obtain a first mixed solution. In the first mixed solution, the concentration of Ni element is 0.67 mol / L, the concentration of Mn element is 0.265 mol / L, and the concentration of Mg element is 0.065 mol / L.

[0199] S2. Add the precipitant sodium hydroxide to the first mixed solution. After a precipitation reaction for 5 h, filter and dry to obtain a precursor.

[0200] S3. Grind and mix lithium hydroxide (lithium salt) and the precursor in a molar ratio of lithium element to Ni element = 1.35:0.67, and then dry to obtain a first mixture.

[0201] S4. Perform low-temperature roasting (i.e., the first roasting treatment) on the first mixture at a roasting temperature of 700 °C for 5 h to obtain a first lithium-rich oxide.

[0202] S5. Wet-mix the first lithium-rich oxide, the first coating agent polyaniline, and the second coating agent glucose in a mass ratio of 93:0.5:4 to obtain a second mixture.

[0203] S6. Dry roast the second mixture (i.e., the second roasting treatment) at a temperature of 700 °C for 8 h to obtain the cathode material.

[0204] Others are the same as in Example 1.

[0205] Example 10

[0206] The difference from Example 1 is as follows:

[0207] 1.1. Prepare the cathode material:

[0208] S1. Dissolve soluble nickel salt nickel sulfate and manganese salt manganese sulfate in water to obtain a first mixed solution. In the first mixed solution, the concentration of Ni element is 0.475 mol / L, and the concentration of Mn element is 0.525 mol / L.

[0209] S2. Add precipitant sodium hydroxide to the first mixed solution, filter and dry after a precipitation reaction for 5 h to obtain the precursor.

[0210] S3. Grind and mix lithium salt lithium hydroxide and the precursor in a molar ratio of lithium element to Ni element = 1.15:0.475, and dry to obtain a first mixture.

[0211] S4. Perform low-temperature roasting (i.e., the first roasting treatment) on the first mixture at a temperature of 700 °C for 5 h to obtain a first lithium-rich oxide, and the first lithium-rich oxide is the cathode material.

[0212] Others are the same as in Example 1.

[0213] Example 11

[0214] The difference from Example 1 is as follows:

[0215] 1.1. Prepare the cathode material:

[0216] S1. Dissolve soluble nickel salt nickel sulfate and manganese salt manganese sulfate in water to obtain a first mixed solution. In the first mixed solution, the concentration of Ni element is 0.475 mol / L, and the concentration of Mn element is 0.525 mol / L.

[0217] S2. Add precipitant sodium hydroxide to the first mixed solution, filter and dry after a precipitation reaction for 5 h to obtain the precursor.

[0218] S3. Grind and mix lithium salt lithium hydroxide and the precursor in a molar ratio of lithium element to Ni element = 1.15:0.475, and dry to obtain a first mixture.

[0219] S4. Carry out low-temperature roasting (i.e., the first roasting treatment) on the first mixture. The roasting temperature is 700 °C and the time is 5 h to obtain the first lithium-rich oxide;

[0220] S5. Wet-mix the first lithium-rich oxide and the second coated glucose in a mass ratio of 93:4.5 to obtain the second mixture;

[0221] S6. Carry out drying roasting (i.e., the second roasting treatment) on the second mixture. The roasting temperature is 700 °C and the time is 8 h to obtain the cathode material.

[0222] Others are the same as in Example 1.

[0223] Comparative Example 1

[0224] The difference from Example 1 lies in:

[0225] 1.1. Prepare the cathode material:

[0226] S1. Dissolve the soluble Ni salt nickel sulfate and the Mn salt manganese sulfate in water to obtain the first mixed solution. In the first mixed solution, the concentration of Ni element is 0.28 mol / L and the concentration of Mn element is 0.602 mol / L;

[0227] S2. Add the precipitant sodium hydroxide to the first mixed solution. After a precipitation reaction for 5 h, filter and dry to obtain the precursor;

[0228] S3. Grind and mix the lithium salt lithium hydroxide and the precursor in a molar ratio of lithium element to Ni element = 1.03:0.28, and dry to obtain the first mixture;

[0229] S4. Carry out low-temperature roasting (i.e., the first roasting treatment) on the first mixture. The roasting temperature is 700 °C and the time is 5 h to obtain the first lithium-rich oxide;

[0230] S5. Wet-mix the first lithium-rich oxide, the first coating agent polyaniline, and the second coating agent glucose in a mass ratio of 93:0.5:4 to obtain the second mixture;

[0231] S6. Carry out drying roasting (i.e., the second roasting treatment) on the second mixture. The roasting temperature is 700 °C and the time is 8 h to obtain the cathode material.

[0232] Others are the same as in Example 1.

[0233] I. Characterize the cathode material provided in Example 1 as follows:

[0234] 1. Morphology characterization: Use a scanning electron microscope to characterize the morphology of the cathode material, and the results are as Figure 1 shown.

[0235] 2. X-ray diffraction (XRD) characterization: The cathode material was characterized by X-ray diffraction, and the results are as follows: Figure 2 as shown.

[0236] II. The following tests were conducted on the batteries provided in each example and each comparative example:

[0237] 1. Specific capacity test process:

[0238] 1.1. Place the battery on the test cabinet for testing. The test steps are as follows: Charge at a constant current of 0.1C to 4.2V, then charge at a constant voltage of 4.2V until the current drops to 0.05C to cut off; let it stand for 10 minutes, discharge at a constant current of 0.1C to 2.0V to cut off, record the discharge capacity q, then the discharge specific capacity of the cathode material = q / m, where m is the mass of the cathode material in the cathode plate; the results are recorded in Table 1;

[0239] 1.2. Place the battery on the test cabinet for testing. The test steps are as follows: Charge at a constant current of 0.1C to 4.5V, then charge at a constant voltage of 4.5V until the current drops to 0.05C to cut off; let it stand for 10 minutes, discharge at a constant current of 0.1C to 2.0V to cut off, record the discharge capacity q, then the discharge specific capacity of the cathode material = q / m, where m is the mass of the cathode material in the cathode plate; the results are recorded in Table 1;

[0240] 1.3. Place the battery on the test cabinet for testing. The test steps are as follows: Charge at a constant current of 0.1C to 4.7V, then charge at a constant voltage of 4.7V until the current drops to 0.05C to cut off; let it stand for 10 minutes, discharge at a constant current of 0.1C to 2.0V to cut off, record the discharge capacity q, then the discharge specific capacity of the cathode material = q / m, where m is the mass of the cathode material in the cathode plate; the results are recorded in Table 1.

[0241] Table 1

[0242]

[0243] 2. Cycle performance test process:

[0244] 2.1. At 25°C, with the voltage range set to 2.5V - 4.2V, charge and discharge the prepared battery at a rate of 1C; during the charging process, charge at a constant current of 1C to 4.2V, then charge at a constant voltage of 4.2V until the current drops to 0.05C to cut off; during the discharging process, discharge at a constant current of 1C to 2.5V to cut off; record the number of cycles when the cycle capacity retention rate is 100%, and the results are recorded in Table 2;

[0245] 2.2. At 25 °C with the voltage range set to 2.5 V - 4.5 V, charge and discharge the prepared battery at a rate of 1C; during the charging process, charge at a constant current of 1C to 4.5 V, and then charge at a constant voltage of 4.5 V until the current drops to 0.05C for cutoff; during the discharging process, discharge at a constant current of 1C until cutoff at 2.5 V; record the number of cycles when the cycle capacity retention rate is 100%, and the results are recorded in Table 2;

[0246] 2.3. At 25 °C with the voltage range set to 2.5 V - 4.7 V, charge and discharge the prepared battery at a rate of 1C; during the charging process, charge at a constant current of 1C to 4.7 V, and then charge at a constant voltage of 4.7 V until the current drops to 0.05C for cutoff; during the discharging process, discharge at a constant current of 1C until cutoff at 2.5 V; record the number of cycles when the cycle capacity retention rate is 100%, and the results are recorded in Table 2.

[0247] Table 2

[0248] Group Chemical formula of the first lithium-rich oxide 4.2V-1C cycle 4.5V-1C cycle 4.7V-1C cycle Example 1 <![CDATA[Li 1.15 Ni 0.475 Mn 0.525 O 2.1 > 4000@100％ 1000@100％ 500@100％ Example 2 <![CDATA[Li 1.10 Ni 0.5 Mn 0.50 O 2.05 > 3500@100％ 700@100％ 400@100％ Example 3 <![CDATA[Li 1.20 Ni 0.45 Mn 0.55 O 2.15 > 4500@100％ 1300@100％ 600@100％ Example 4 <![CDATA[Li 1.45 Ni 0.375 Mn 0.625 O 2.35 > 1000@100％ 600@100％ 500@100％ Example 5 <![CDATA[Li 1.60 Ni 0.54 Mn 0.38 Al 0.08 O 2.3 > 6000@100％ 2000@100％ 800@100％ Example 6 <![CDATA[Li 1.35 Ni 0.54 Mn 0.36 Al 0.1 O 2.2 > 2000@100％ 800 @ 100% 500 @ 100% Example 7 <![CDATA[Li 1.15 Ni 0.73 Mn 0.185 Al 0.085 O 2.1 > 3800 @ 100% 1000 @ 100% 500@100％ Example 8 <![CDATA[Li 1.20 Ni 0.74 Mn 0.18 Zr 0.08 O 2.10 > 4800 @ 100% 1200 @ 100% 800@100％ Example 9 <![CDATA[Li 1.35 Ni 0.67 Mn 0.265 Mg 0.065 O 2.2 > 5000@100％ 1500@100％ 600@100％ Example 10 <![CDATA[Li 1.15 Ni 0.475 Mn 0.525 O 2.1 > 3600 @ 100% 850@100％ 470@100％ Example 11 <![CDATA[Li 1.15 Ni 0.475 Mn 0.525 O 2.1 > 3900@100％ 920@100％ 500@100％ Comparative Example 1 <![CDATA[Li 1.03 Ni 0.28 Mn 0.602 O2]]> 900@100％ 500@100％ 400@100％

[0249] III. Result Analysis

[0250] 3.1. From the test results in Table 1 and Table 2, it can be seen that when comparing Examples 1 to 11 with Comparative Example 1, whether under low voltage (4.2 V) or high voltage (4.7 V), the specific capacity per gram of the positive electrode material in the battery and the cycle performance of the battery in Examples 1 to 11 are better than those in Comparative Example 1. This is because, compared with the positive electrode material provided in Comparative Example 1, the positive electrode materials provided in Examples 1 to 11 have a higher lithium and nickel content and a lower manganese content. By increasing the lithium content, the energy density of the positive electrode material can be improved. Combining the increase in nickel content and the decrease in manganese content can lower the activation energy barrier of the positive electrode material, so that the positive electrode material can exhibit a higher specific capacity per gram at a lower activation voltage, broaden the voltage window of the positive electrode material, and improve the cycle performance of the battery.

[0251] 3.2. From the test results in Table 1 and Table 2, it can be seen that when comparing Examples 1 - 4, 10 - 11 with Examples 5 - 9, the positive electrode materials provided in Examples 5 - 9 are also doped with other metals in addition to Li, Ni, and Mn. By comparing the 4.2V / 4.7V specific capacity ratio (i.e., the ratio of the specific capacity at 4.2 V to the specific capacity at 4.7 V), it can be seen that the 4.2V / 4.7V specific capacity ratio of Examples 5 - 9 is slightly higher than that of Examples 1 - 4 and 10 - 11, indicating that doping with other metals can also further reduce the activation energy barrier of the positive electrode material to a certain extent.

[0252] 3.3. As can be seen from the test results in Table 1 and Table 2, compared with Example 11, in Example 1, the first lithium-rich oxide in the cathode material provided is also mixed with the first coating agent polyaniline and the second coating agent glucose and then calcined during the preparation process. As a result, a carbon coating layer can be formed on the first lithium-rich oxide, and the thermal decomposition of polyaniline during calcination can also enable nitrogen elements to dope the first lithium-rich oxide. In the preparation process of the cathode material of Example 11, the first lithium-rich oxide is mixed with the second coating agent glucose and then calcined, so that a carbon coating layer can be formed on the first lithium-rich oxide. Since it is not mixed with the second coating agent polyaniline, the first lithium-rich oxide is not nitrogen-doped. From the electrochemical test results, it can be seen that their specific capacities at different voltages are close, but the cycling performance of Example 1 at different voltages is better than that of Example 11. This is because after the first lithium-rich oxide is doped with nitrogen elements, the structure of the first lithium-rich oxide becomes more stable during the lithium-ion insertion and extraction process, reducing the risk of lattice expansion or contraction of the first lithium-rich oxide, and thus improving the cycling performance of the battery.

[0253] 3.4. As can be seen from the test results in Table 1 and Table 2, compared with Example 1 and Example 10, the cathode material provided by Example 11 only contains the first lithium-rich oxide, and there is neither a carbon coating layer on the surface of the first lithium-rich oxide nor nitrogen doping in the first lithium-rich oxide. Example 11 has the worst cycling performance among the three. This is because the carbon coating layer on the surface of the first lithium-rich oxide is relatively easy to be infiltrated by the electrolyte, so that the carbon coating layer forms an intermediate transition region, and then a gradient change in the lithium-ion distribution from the electrolyte to the coating layer and then to the first lithium-rich oxide is formed. This can assist the lithium-ion deintercalation and improve the cycling performance of the battery.

[0254] The embodiments of the present application have been introduced in detail above. Specific examples are used in this article to elaborate on the principle and implementation manner of the present application. The description of the above embodiments is only used to help understand the method and its core idea of the present application; at the same time, for those skilled in the art, according to the idea of the present application, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present application.

Claims

1. A cathode material, characterized in that, including a lithium-rich oxide, the chemical formula of the lithium-rich oxide being Li 1+ x Mn y Ni z M a B r , where M is a doped metal element, B includes oxygen element, and in terms of molar ratio, 0.1 ≤ x ≤ 1.0, 0 ≤ y ≤ 1.0, 0.30 ≤ z ≤ 0.95, 0 ≤ a ≤ 0.1, 2.0 ≤ r ≤ 2.

7.

2. The cathode material according to claim 1, characterized in that, B further includes nitrogen element.

3. The cathode material according to claim 2, characterized in that, Based on the total mass of the positive electrode material, the doping amount of the nitrogen element is less than or equal to 1.0 wt%.

4. The cathode material according to claim 1, characterized in that, The surface of the lithium-rich oxide is provided with a carbon coating layer.

5. The cathode material according to claim 4, characterized in that, The carbon in the carbon coating layer includes graphitized amorphous carbon. Based on the total mass of the carbon coating layer, the content of the graphitized amorphous carbon is less than or equal to 10 wt%; and / or, the thickness of the carbon coating layer is 1 nm - 10 nm.

6. The cathode material according to claim 5, characterized in that, Based on the total mass of the positive electrode material, the content of the graphitized amorphous carbon is less than or equal to 3 wt%.

7. The cathode material according to any one of claims 1 to 6, characterized in that, The doped metal element includes at least one of Fe, Al, Mg, Ti, Nb, and Zr.

8. The cathode material according to any one of claims 1 to 6, characterized in that, In terms of molar ratio, 0.1 ≤ x ≤ 0.6, 0.18 ≤ y ≤ 0.625, 0.375 ≤ z ≤ 0.74, 0 ≤ a ≤ 0.1, 2.05 ≤ r ≤ 2.

35.

9. The cathode material according to any one of claims 1 to 6, characterized in that, The positive electrode material is granular, and the D50 particle size of the positive electrode material is 1.0 μm - 15.0 μm.

10. A method for preparing a cathode material, which is used to prepare the cathode material according to any one of claims 1 to 9, characterized in that, Including: Provide a first lithium-rich oxide, the chemical formula of the first lithium-rich oxide being Li 1+x Mn y Ni z M a O r , where M is a doped metal element, and in terms of molar ratio, 0.1 ≤ x ≤ 1.0, 0 ≤ y ≤ 1.0, 0.30 ≤ z ≤ 0.95, 0 ≤ a ≤ 0.1, 2.0 ≤ r ≤ 2.7; Obtaining the positive electrode material based on the first lithium-rich oxide.

11. The method for preparing the cathode material according to claim 10, wherein, The providing of the first lithium-rich oxide includes: Adding a nickel source and a manganese source into a solvent to obtain a first mixed solution; Adding a precipitating agent into the first mixed solution, and after filtration and drying treatment, obtaining a precursor; Performing a first mixing treatment on the lithium source and the precursor to obtain a first mixture; Performing a first calcination treatment on the first mixture to obtain a first lithium-rich oxide.

12. The method for preparing a cathode material according to claim 11, wherein, When preparing the first mixed solution, a doped metal source is further added into the solvent.

13. The method for preparing the cathode material according to claim 11, wherein, The obtaining of the positive electrode material based on the first lithium-rich oxide includes: Performing a second mixing treatment on the first coating agent and the first lithium-rich oxide to obtain a second mixture. The first coating agent is an organic compound containing nitrogen element; The second mixture is subjected to a second roasting treatment to obtain a second lithium-rich oxide, and the surface of the second lithium-rich oxide is coated with a carbon coating layer. The chemical formula of the second lithium-rich oxide is Li 1+x Mn y Ni z M a B r , where M is a doped metal element, B includes O and N, and in terms of molar ratio, 0.1 ≤ x ≤ 1.0, 0 ≤ y ≤ 1.0, 0.30 ≤ z ≤ 0.95, 0 ≤ a ≤ 0.1, 2.0 ≤ r ≤ 2.

7.

14. The preparation method of the positive electrode material according to claim 13, characterized in that, When preparing the second mixture, a second coating agent is further added into the first lithium-rich oxide. The carbonization temperature of the second coating agent is lower than that of the first coating agent.

15. According to the method for preparing a positive electrode material as claimed in claim 14, wherein The first coating agent includes at least one of polyaniline and melamine; and / or, The second coating agent includes at least one of glucose, polyethylene glycol, sucrose, polyaniline, and polypyrrole; and / or, In the second mixture, by mass ratio, the first coating agent: the second coating agent: the first lithium-rich oxide is (0.1 - 2.0): (3.0 - 6.0): (92 - 94); and / or, The temperature of the second calcination treatment is 600 °C - 800 °C, and the time is 6 h - 12 h.

16. According to the method for preparing a positive electrode material as claimed in claim 12, wherein The nickel source includes at least one of nickel sulfate, nickel nitrate, nickel acetate, nickel carbonate, and nickel chloride; and / or, The manganese source includes at least one of manganese sulfate, manganese nitrate, manganese carbonate, manganese acetate, manganese tetraoxide, and manganese dioxide; and / or, The doped metal source includes at least one of iron salts, aluminum salts, magnesium salts, titanium salts, niobium salts, and zirconium salts; and / or, The solvent includes water; and / or, In the first mixed solution, the molar ratio of manganese element, nickel element and doped metal element is (0 to 1.0):(0.3 to 0.95):(0 to 0.1); and / or, In the first mixed solution, the concentration of manganese element is 0.1 mol / L to 0.65 mol / L, the concentration of nickel element is 0.3 mol / L to 1.5 mol / L, and the concentration of doped metal element is 0.01 mol / L to 0.1 mol / L.

17. The method for preparing the positive electrode material according to claim 11, wherein The precipitating agent includes at least one of sodium hydroxide and potassium hydroxide; and / or, After adding the precipitating agent, the concentration of the precipitating agent in the first mixed solution is 0.1 mol / L to 2.0 mol / L; and / or, After adding the precipitating agent, the pH of the first mixed solution is 8 to 11; and / or, The time of the precipitation reaction is 3 h to 10 h.

18. The method for preparing the positive electrode material according to claim 11, wherein The lithium source includes at least one of lithium hydroxide, lithium carbonate and lithium oxide; and / or, In the first mixture, the molar ratio of lithium element in the lithium source to nickel element in the precursor is 1.2 to 4.0; and / or, The first mixing treatment is a grinding treatment; and / or, The time of the first mixing treatment is 30 min to 180 min; and / or, The temperature of the first calcination treatment is 600 °C to 800 °C, and the time is 3 to 8 h.

19. A positive electrode sheet, characterized in that, It includes a positive electrode current collector and a positive electrode film layer combined with the positive electrode current collector, and the positive electrode film layer includes the positive electrode material according to any one of claims 1 to 9 or the positive electrode material prepared by the method for preparing the positive electrode material according to any one of claims 10 to 18.

20. A battery, characterized in that, It includes the positive electrode plate according to claim 19.

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