A high-nickel ternary positive electrode material, a preparation method and use thereof

Abstract

The application belongs to the technical field of batteries, and provides a high-nickel ternary positive electrode material, a preparation method and application thereof.The high-nickel ternary positive electrode material comprises a high-nickel main material and a coating layer arranged on the surface of the high-nickel main material, and the coating layer comprises lithium peroxide.The lithium peroxide coating can play a protective and isolating role of the coating layer, improve the cycle performance, and produce a lithium supplement effect without causing capacity damage to the high-nickel main material.The preparation method introduces peroxide during high-temperature calcination to form the high-nickel main material, effectively reduces the mixing degree of lithium and nickel in the high-nickel and super-high-nickel ternary main material, washes the obtained high-nickel main material in a lithium-containing aqueous solution, realizes lithium hydroxide coating while washing away lithium carbonate, suppresses the damage of water to the main material, and generates a rock salt phase protective layer on the surface of the main material, further enhancing the cycle stability of the material.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of batteries, and relates to a high-nickel ternary positive electrode material and a preparation method and application thereof. BACKGROUND

[0002] With the transformation of global energy structure and the enhancement of environmental protection awareness, the rapid development of power automobiles and energy storage technology has become an important force to promote green economy. Under this background, lithium ion batteries, as the core components of energy storage and conversion, have shown broad application prospects in electric vehicles, portable electronic devices, smart grids, aerospace and other fields due to their high energy density, long cycle life, no memory effect and environmental friendliness.

[0003] Lithium ion batteries are mainly composed of key components such as positive electrodes, negative electrodes, electrolytes and separators. The positive electrode material is the main embedding and de-embedding place of lithium ions, and its performance directly affects the overall performance of the battery. According to the different positive electrode materials, lithium ion batteries can be divided into lithium cobaltate, lithium manganate, lithium iron phosphate and ternary materials. Among them, ternary materials (i.e. nickel cobalt lithium manganate / nickel cobalt lithium aluminate) have rapidly developed in the field of power automobiles due to their excellent comprehensive performance, especially high energy density characteristics.

[0004] The energy density of ternary positive electrode materials can be significantly improved by adjusting the proportion of nickel. However, with the further increase of nickel content, the process gradually shifts to high-nickel ternary materials (Ni content of 60% to 90%) or super-high-nickel ternary materials (Ni content > 90%), which also brings some problems. For example, in the actual charging and discharging process, the repeated embedding and de-embedding of lithium ions can easily lead to the destruction of the material structure, thereby causing capacity decay and cycle performance decline. In addition, the surface of high-nickel materials has high chemical activity, which is easy to react with the electrolyte to form a solid-state electrolyte interface film (SEI). This not only consumes active lithium, but also increases the internal resistance of the battery, affecting the performance and life of the battery.

[0005] In view of the above problems existing in high-nickel ternary materials, researchers have proposed optimization methods such as high-valence element doping and dense protective layer coating. However, although high-valence element doping can enhance the structural stability of the material, excessive doping amount may introduce new defects, affecting the electrochemical performance such as capacity of the material; while the dense protective layer coating can effectively isolate the direct contact between the material and the electrolyte, but the existence of the coating layer often leads to a decrease in the proportion of the positive electrode material, thereby causing a decrease in capacity.

[0006] Therefore, how to find a solution that can effectively improve the cycle performance of super-high-nickel ternary positive electrode materials without damaging the capacity of the material is a problem to be solved in the current field. SUMMARY

[0007] In view of the problems in the prior art, the purpose of the present application is to provide a high-nickel ternary positive electrode material and a preparation method and use thereof, comprising a high-nickel main material and a coating layer arranged on the surface of the high-nickel main material, wherein the coating layer comprises lithium peroxide. The present application can not only play a protective and isolating role of the coating layer and improve the cycle performance by coating lithium peroxide, but also can produce a lithium supplement effect without causing capacity damage to the high-nickel main material.

[0008] To achieve this purpose, the present application adopts the following technical solutions:

[0009] In a first aspect, the present application provides a high-nickel ternary positive electrode material, comprising a main material, wherein the chemical formula of the main material comprises LiNi x Co y Mn z O2, wherein x≥0.6, y>0, z>0, and x+y+z=1; and a coating layer arranged on the surface of the main material, wherein the coating layer comprises lithium peroxide.

[0010] By arranging the coating layer comprising lithium peroxide on the surface of the high-nickel main material, the present application can not only play a protective and isolating role of the coating layer and improve the cycle performance by coating lithium peroxide, but also can produce a lithium supplement effect without causing capacity damage to the high-nickel main material.

[0011] The following is a preferred technical solution of the present application, but is not a limitation of the technical solutions provided by the present application. Through the following technical solution, the technical purpose and beneficial effects of the present application can be better achieved and realized.

[0012] As a preferred technical solution of the present application, the main material is an ultrahigh-nickel ternary positive electrode material, and x>0.9.

[0013] In a second aspect, the present application provides a preparation method of the high-nickel ternary positive electrode material of the first aspect, wherein the preparation method comprises:

[0014] (1) mixing a precursor Ni x Co y Mn z (OH)2, a lithium source and a peroxide, and performing calcination to obtain a main material LiNi x Co y Mn z O2, wherein x≥0.6, y>0, z>0, and x+y+z=1;

[0015] (2) coating the obtained main material LiNi x Co y Mn zO2 is mixed with a lithium-containing aqueous solution, in the main material LiNi x Co y Mn z A lithium hydroxide pre-coating layer is formed on the surface of O2 to obtain a pre-coated body;

[0016] (3) The obtained pre-coated body is heat-treated in an ozone atmosphere to transform the lithium hydroxide pre-coated layer into a lithium peroxide coating layer, thereby obtaining a high-nickel ternary cathode material.

[0017] In the preparation method described in this invention, peroxide is introduced during the high-temperature calcination process in step (1), which reduces the Ni content in the material. 2+ The ratio of lithium to nickel is reduced, thereby effectively reducing the mixing degree of lithium and nickel in high-nickel and ultra-high-nickel ternary main materials, and further enhancing the cycling performance of the materials; in step (2), mixing in a lithium-containing aqueous solution has the effect of water washing. While washing away the lithium carbonate on the surface of the main material, it can also achieve the coating of lithium hydroxide through lithium-containing compounds, inhibit the damage of water to the main material, and generate a rock salt phase protective layer on the surface of the main material, further enhancing the cycling stability of the material; the heat treatment in step (3) is low-temperature sintering, and an ozone-containing atmosphere is used to convert the lithium hydroxide on the surface into a lithium peroxide coating layer. The reaction principle includes: 2LiOH+O3→Li2O2+H2O+O2, which can both play the role of coating layer and replenish lithium in the material. That is, the lithium replenishment principle in the charging process includes: Li2O2→2Li + +O2+2e - This improves the capacity of the resulting high-nickel ternary cathode material.

[0018] It should be noted that, since the residual lithium in the low-nickel ternary material (x < 0.6) is very low, washing it with water in the lithium-containing aqueous solution in step (2) of the preparation method described in this invention will actually affect the material performance.

[0019] As a preferred technical solution of the present invention, in step (1), the precursor Ni x Co y Mn z The molar ratio of (OH)2 to the molar ratio of lithium in the lithium source is 1:(1~1.2).

[0020] As a preferred technical solution of the present invention, in step (1), the lithium source includes any one of lithium oxalate, lithium carbonate, lithium hydroxide monohydrate, lithium acetate, or lithium citrate.

[0021] As a preferred technical solution of the present invention, in step (1), the precursor Ni x Co y Mn z The molar ratio of (OH)2 to the molar ratio of the peroxide is 1:(0.001 to 0.01).

[0022] As a preferred technical solution of the present application, in step (1), the peroxide includes any one of lithium peroxide, sodium peroxide, nickel peroxide, strontium peroxide, or barium peroxide.

[0023] As a preferred technical solution of the present application, in step (1), the temperature of the calcination is 700-1100℃, and the time is 10-20h.

[0024] As a preferred technical solution of the present application, in step (2), the concentration of lithium element in the lithium-containing aqueous solution is 0.5-5mol / L.

[0025] As a preferred technical solution of the present application, the mass ratio of the lithium-containing aqueous solution to the main material LiNi x Co y Mn z O2 is (0.1-1):1.

[0026] As a preferred technical solution of the present application, the method for preparing the lithium-containing aqueous solution in step (2) includes adding a lithium-containing compound into water with a temperature of 0-40℃, and stirring at 100-300rpm for 2-20min.

[0027] As a preferred technical solution of the present application, the lithium-containing compound includes at least one of lithium oxalate, lithium oxide, lithium hydroxide monohydrate, lithium acetate, or lithium citrate.

[0028] As a preferred technical solution of the present application, in step (2), the main material LiNi x Co y Mn z O2 is mixed with the lithium-containing aqueous solution for 10-60min.

[0029] As a preferred technical solution of the present application, in step (2), the main material LiNi x Co y Mn z O2 is mixed with the lithium-containing aqueous solution, and then the mixed solution is centrifuged at 40-60Hz for 0.5-1.5h to obtain a centrifugate; the centrifugate is vacuum dried at 100-180℃ for 2-20h, and then sieved through a 280-320mesh sieve to obtain undersize; the obtained undersize is used as the pre-coated body in step (3).

[0030] As a preferred technical solution of the present application, in step (3), in the atmosphere containing ozone, the volume of ozone accounts for 1%-10%.

[0031] As a preferred technical solution of the present application, the temperature of the heat treatment is 200-400℃, and the time is 5-10h.

[0032] In a third aspect, the present application provides a positive electrode sheet, which contains the high-nickel ternary positive electrode material of the first aspect.

[0033] In a fourth aspect, the present application provides a battery, which contains the positive electrode sheet of the third aspect.

[0034] Compared with the prior art, the present application has at least the following beneficial effects:

[0035] By arranging the coating layer including lithium peroxide on the surface of the high-nickel main material, the coating with lithium peroxide can not only play a protective and isolating role of the coating layer to improve the cycle performance, but also produce a lithium supplement effect, which will not cause capacity damage to the high-nickel main material, and can also improve the capacity performance of the obtained high-nickel ternary positive electrode material.

[0036] In the preparation method, by introducing peroxide in the high-temperature calcination process, the mixing degree of lithium and nickel in the high-nickel and super-high-nickel ternary main material is effectively reduced, and the cycle performance of the material is further enhanced; by mixing in the lithium-containing aqueous solution, the effect of water washing is achieved, the lithium carbonate on the surface of the main material is washed away, and at the same time, lithium hydroxide can be coated by the lithium-containing compound to inhibit the damage of water to the main material, and a rock salt phase protective layer is generated on the surface of the main material, further enhancing the cycle stability of the material. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 is the SEM test graph of the high-nickel ternary material obtained in Example 1;

[0038] Figure 2 is the XRD test graph of the high-nickel ternary material obtained in Example 1;

[0039] Figure 3 is the cycle performance test graph of the ternary material obtained in Example 1, Example 5, Example 7 and Comparative Example 2. DETAILED DESCRIPTION

[0040] The technical solutions of the present application will be further described below through specific embodiments. Those skilled in the art should understand that the embodiments and examples are only to help understand the present application, and should not be regarded as specific limitations on the present application.

[0041]

High-nickel ternary positive electrode material

[0042] In some specific embodiments, the present application provides a high-nickel ternary positive electrode material, which includes a main material, and the chemical formula of the main material includes LiNi x Co y Mn zO2, wherein x≥0.6, y>0, z>0, x+y+z=1; the surface of the main material is provided with a cladding layer, and the cladding layer comprises lithium peroxide.

[0043] In one embodiment, the chemical formula of the main material is LiNi x Co y Mn z O2, wherein x≥0.6, for example, x can be 0.6, 0.63, 0.65, 0.68, 0.7, 0.73, 0.75, 0.78, 0.8, 0.82, 0.85, 0.88, 0.9, 0.92, 0.94 or 0.96, etc., preferably >0.9 (ultra-high nickel ternary positive electrode material); y>0, for example, y can be 0.01, 0.05, 0.08, 0.1, 0.13, 0.15, 0.18, 0.2, 0.22, 0.25, 0.28, 0.3, 0.32, 0.35 or 0.39, etc.; z>0, for example, z can be 0.01, 0.05, 0.08, 0.1, 0.13, 0.15, 0.18, 0.2, 0.22, 0.25, 0.28, 0.3, 0.32, 0.35 or 0.39, etc.

[0044] Preparation method of high-nickel ternary positive electrode material

[0045] In some specific embodiments, the present application provides a preparation method of the high-nickel ternary positive electrode material described in the above embodiments, and the preparation method comprises:

[0046] (1) mixing a precursor Ni x Co y Mn z (OH)2, a lithium source and a peroxide, and performing calcination to obtain a main material LiNi x Co y Mn z O2, wherein x≥0.6, y>0, z>0, x+y+z=1;

[0047] (2) mixing the obtained main material LiNi x Co y Mn z O2 with a lithium-containing aqueous solution to form a lithium hydroxide pre-cladding layer on the surface of the main material LiNi x Co y Mn z O2, to obtain a pre-cladding body;

[0048] (3) performing heat treatment on the obtained pre-cladding body in an atmosphere containing ozone, so that the lithium hydroxide pre-cladding layer is converted into a lithium peroxide cladding layer, to obtain a high-nickel ternary positive electrode material.

[0049] In one embodiment, in step (1), the precursor Ni x Co y Mn z The ratio of the molar amount of the precursor Ni

[0050] In one embodiment, in step (1), the lithium source comprises any one of lithium oxalate, lithium carbonate, lithium hydroxide monohydrate, lithium acetate, or lithium citrate.

[0051] In one embodiment, in step (1), the precursor Ni x Co y Mn z The ratio of the molar amount of the precursor Ni

[0052] In one embodiment, in step (1), the peroxide comprises any one of lithium peroxide, sodium peroxide, nickel peroxide, strontium peroxide, or barium peroxide.

[0053] In one embodiment, in step (1), the temperature of the calcination is 700-1100 °C, such as 700 °C, 730 °C, 750 °C, 780 °C, 800 °C, 820 °C, 850 °C, 880 °C, 900 °C, 930 °C, 950 °C, 980 °C, 1000 °C, 1030 °C, 1050 °C, 1080 °C, or 1100 °C, etc., and the time is 10-20 h, such as 10 h, 11 h, 12 h, 13 h, 14 h, 15 h, 16 h, 17 h, 18 h, 19 h, or 20 h, etc.

[0054] In one embodiment, in step (2), the concentration of lithium element in the lithium-containing aqueous solution is 0.5-5 mol / L, such as 0.5 mol / L, 0.8 mol / L, 1 mol / L, 1.3 mol / L, 1.5 mol / L, 1.8 mol / L, 2 mol / L, 2.3 mol / L, 2.5 mol / L, 2.8 mol / L, 3 mol / L, 3.3 mol / L, 3.5 mol / L, 3.8 mol / L, 4 mol / L, 4.2 mol / L, 4.5 mol / L, 4.8 mol / L, or 5 mol / L, etc.

[0055] In one embodiment, in step (2), the lithium-containing aqueous solution is mixed with the host material LiNi x Co y Mn z O2in a mass ratio of (0.1-1): 1, for example 0.1:1, 0.2:1, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, or 1:1, etc., but not limited to the listed values, other values within the above range are also applicable.

[0056] In one embodiment, the method of preparing the lithium-containing aqueous solution in step (2) comprises adding a lithium-containing compound to water at a temperature of 0-40°C, for example 0°C, 5°C, 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, or 40°C, etc., preferably 0-20°C, and stirring at 100-300 rpm, for example 100 rpm, 130 rpm, 150 rpm, 180 rpm, 200 rpm, 230 rpm, 250 rpm, 280 rpm, or 300 rpm, etc., for 2-20 min, for example 2 min, 5 min, 8 min, 10 min, 12 min, 14 min, 16 min, 18 min, or 20 min, etc.

[0057] In one embodiment, the lithium-containing compound comprises at least one of lithium oxalate, lithium oxide, lithium hydroxide monohydrate, lithium acetate, or lithium citrate.

[0058] In one embodiment, in step (2), the lithium-containing aqueous solution is mixed with the host material LiNi x Co y Mn z O2in a mass ratio of (0.1-1): 1, for example 0.1:1, 0.2:1, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, or 1:1, etc., but not limited to the listed values, other values within the above range are also applicable.

[0059] In one embodiment, in step (2), the lithium-containing aqueous solution is mixed with the host material LiNi x Co y Mn zO2 is mixed with the lithium-containing aqueous solution, and the mixed solution is centrifuged at 40-60 Hz, for example, 40 Hz, 45 Hz, 50 Hz, 55 Hz, or 60 Hz, etc., for 0.5-1.5 h, for example, 0.5 h, 0.8 h, 1 h, 1.2 h, or 1.5 h, etc., to obtain a centrifugate; the centrifugate is vacuum dried at 100-180℃, for example, 100℃, 120℃, 140℃, 160℃, or 180℃, etc., for 2-20 h, for example, 2 h, 4 h, 6 h, 8 h, 10 h, 12 h, 14 h, 16 h, 18 h, or 20 h, etc., and then sieved through a 280-320 mesh sieve, for example, 280 mesh, 290 mesh, 300 mesh, 310 mesh, or 320 mesh, etc., to obtain undersize; the obtained undersize is used as the pre-coated body in step (3).

[0060] In one embodiment, in step (3), the volume of ozone in the ozone-containing atmosphere is 1%-10%, for example, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, or 10%, etc.

[0061] In one embodiment, the ozone-containing atmosphere is a mixed atmosphere of ozone and oxygen.

[0062] In one embodiment, the temperature of the heat treatment is 200-400℃, for example, 200℃, 220℃, 240℃, 260℃, 280℃, 300℃, 320℃, 340℃, 360℃, 380℃, or 400℃, etc., and the time is 5-10 h, for example, 5 h, 5.5 h, 6 h, 6.5 h, 7 h, 7.5 h, 8 h, 8.5 h, 9 h, 9.5 h, or 10 h, etc.

[0063] It should be noted that, due to the limitation of the length and in order to avoid redundancy, the present application does not list all the point values in the above numerical range, but also is not limited to the listed values, other unlisted values in the above numerical range are also applicable.

[0064] [Positive electrode tab]

[0065] In some specific embodiments, the present application provides a positive electrode tab, which contains the high-nickel ternary positive electrode material in the above embodiments.

[0066] In one embodiment, the positive electrode tab comprises a positive electrode current collector and a positive electrode active layer disposed on the positive electrode current collector, the positive electrode active layer comprises a positive electrode active material, the positive electrode active material comprises the high-nickel ternary positive electrode material, and further comprises a positive electrode conductive agent and a positive electrode binder.

[0067] [Positive electrode current collector]

[0068] The specific selection of the positive electrode current collector is not specifically limited in the present application, and a person skilled in the art can reasonably select and adjust according to actual needs, for example:

[0069] In one embodiment, the positive electrode current collector comprises a first metal foil or a first composite current collector.

[0070] In one embodiment, the first metal foil comprises an aluminum foil or a carbon-coated aluminum foil.

[0071] In one embodiment, the first composite current collector comprises a first polymer material base layer and a first metal layer formed on the first polymer material base layer.

[0072] In one embodiment, the metal material of the first metal layer comprises aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver or silver alloy, etc.

[0073] In one embodiment, the material of the first polymer material base layer comprises polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene or polyethylene, etc.

[0074] [Positive electrode conductive agent and positive electrode binder]

[0075] The present application does not specifically limit the type and proportion of the positive electrode conductive agent and the positive electrode binder in the active layer, and a person skilled in the art can reasonably select and adjust according to actual needs, for example:

[0076] In one embodiment, the positive electrode conductive agent comprises at least one of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene or carbon nanofibers.

[0077] In one embodiment, the positive electrode binder comprises at least one of polyvinylidene fluoride, styrene-butadiene rubber, polyacrylic acid, sodium polyacrylate, polyacrylamide, polyvinyl alcohol, sodium alginate, polymethacrylic acid or carboxymethyl chitosan.

[0078] [Manufacturing method of positive electrode sheet]

[0079] The present application does not specifically limit the manufacturing method of the positive electrode sheet, and a person skilled in the art can reasonably select and adjust according to actual needs, for example:

[0080] In one embodiment, the manufacturing method of the positive electrode sheet comprises mixing a positive electrode active material, a positive electrode conductive agent, a positive electrode binder and a positive electrode solvent to prepare a positive electrode slurry; coating the positive electrode slurry on a positive electrode current collector, and drying to obtain a positive electrode sheet.

[0081] In one embodiment, the positive electrode solvent comprises N-methylpyrrolidone.

[0082]

Battery

[0083] In some embodiments, the present application provides a battery comprising the positive electrode plate as described in the above embodiments.

[0084] In one embodiment, the battery comprises the positive electrode plate, and a negative electrode plate, a separator, and an electrolyte.

[0085] [Negative electrode plate]

[0086] The present application does not make specific limitations on the specific selection of the negative electrode plate and the method for making the same, and the person skilled in the art can make reasonable selection and adjustment according to the actual needs. Exemplarily:

[0087] In one embodiment, the negative electrode plate comprises a negative current collector and a negative active layer disposed on the negative current collector, wherein the negative active layer comprises a negative active material, a negative conductive agent, and a negative binder.

[0088] In one embodiment, the negative current collector comprises a second metal foil or a second composite current collector.

[0089] In one embodiment, the second metal foil comprises a copper foil.

[0090] In one embodiment, the second composite current collector comprises a second polymer material base layer and a second metal layer formed on the second polymer material base layer.

[0091] In one embodiment, the metal material of the second metal layer comprises copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, or silver alloy, etc.

[0092] In one embodiment, the material of the second polymer material base layer comprises polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, or polyethylene, etc.

[0093] In one embodiment, the negative active material comprises artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based material, tin-based material, and lithium titanate, etc.

[0094] In one embodiment, the silicon-based material comprises at least one of elemental silicon, silicon oxide compound, silicon-carbon composite, silicon-nitrogen composite, or silicon alloy.

[0095] In one embodiment, the tin-based material comprises at least one of elemental tin, tin oxide compound, or tin alloy.

[0096] In an embodiment, the negative electrode conductive agent includes at least one of super P, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, or carbon nanofibers.

[0097] In an embodiment, the negative electrode binder includes at least one of styrene butadiene rubber, polyacrylic acid, sodium polyacrylate, polyacrylamide, polyvinyl alcohol, sodium alginate, polymethacrylic acid, and carboxymethyl chitosan.

[0098] In an embodiment, the method for manufacturing the negative electrode tab includes mixing the negative electrode active material, the negative electrode conductive agent, the negative electrode binder, and the negative electrode solvent to form a negative electrode slurry; and coating the negative electrode slurry on a negative electrode current collector to obtain the negative electrode tab after drying, cold pressing, and the like.

[0099] In an embodiment, the negative electrode solvent includes N-methylpyrrolidone.

[0100] [Separator]

[0101] The present application does not have a particular limitation on the type and selection of the separator, and any known porous structure separator having good chemical stability and mechanical stability can be selected, exemplarily including:

[0102] In an embodiment, the material of the separator includes at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, or polyvinylidene fluoride.

[0103] In an embodiment, the separator is a single-layer film or a multi-layer composite film.

[0104] In an embodiment, the separator is a multi-layer composite film, and the materials of the layers are the same or different.

[0105] [Electrolyte]

[0106] The present application does not have a particular limitation on the type and selection of the electrolyte, and the electrolyte can be selected according to the requirements, exemplarily including:

[0107] In an embodiment, the electrolyte is a solid-state electrolyte or a liquid-state electrolyte (i.e., electrolyte solution).

[0108] In an embodiment, the electrolyte is an electrolyte solution, and the electrolyte solution includes an electrolyte salt and a dissolving solvent.

[0109] In an embodiment, the electrolyte salt includes at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bisfluorosulfonylimide, lithium bis-trifluoromethanesulfonylimide, lithium trifluoromethanesulfonate, lithium difluoro oxalate borate, lithium difluoro oxalate borate, lithium difluorophosphate, lithium difluoro di-oxalate phosphate, or lithium tetrafluoro oxalate phosphate.

[0110] In one embodiment, the solubilizing solvent includes at least one of ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, butane sulfone, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone.

[0111] In one embodiment, the electrolyte further includes an additive; the additive includes a negative electrode film-forming additive and / or a positive electrode film-forming additive, and can further include an additive capable of improving certain performance of the battery, such as an additive capable of improving overcharge performance of the battery, an additive capable of improving high-temperature performance of the battery, and an additive capable of improving low-temperature performance of the battery, etc.

[0112] Example 1

[0113] The present embodiment provides a high-nickel ternary material, including a main material, a chemical formula of the main material including LiNi 0.93 Co 0.03 Mn 0.04 O2, a surface of the main material being provided with a coating layer, the coating layer being lithium peroxide;

[0114] A preparation method of the high-nickel ternary material includes:

[0115] (1) 20 kg of nickel-cobalt-manganese hydroxide precursor Ni 0.93 Co 0.03 Mn 0.04 (OH)2is mechanically mixed with 9.24 kg of lithium source lithium monohydrate and 19.8 g of peroxide lithium peroxide using a plow mixer at a speed of 50 Hz for 30 min, and then the mixture is calcined at 800°C for 15 h in an oxygen atmosphere to obtain a main material LiNi 0.93 Co 0.03 Mn 0.04 O2;

[0116] (2) 12 L of deionized water is taken, the water temperature is 0.5°C, 1006.58 g of lithium-containing compound lithium monohydrate is added to the water, and after stirring for 10 min using a mechanical stirrer at 200 rpm, 20 kg of the obtained main material LiNi 0.93 Co 0.03 Mn 0.04 O2is stirred for 10 min to coat the main material LiNi 0.93 Co 0.03 Mn 0.04The surface of O2 is formed with a lithium hydroxide pre-coating layer, placed in a centrifuge, centrifuged at 50 Hz for 1 h to obtain a centrifugate, and then the centrifugate is placed in a vacuum drying box and dried at 120°C for 10 h. After the material is dried, it is sieved through a 200-mesh sieve to obtain a pre-coated body;

[0117] (3) 15 kg of the pre-coated body is heat treated at 240°C for 8 h in a mixed gas atmosphere with a volume ratio of oxygen to ozone of 90:10. The lithium hydroxide pre-coating layer is converted into a lithium peroxide coating layer to obtain a high-nickel ternary positive electrode material.

[0118] Example 2

[0119] The present embodiment provides a high-nickel ternary material, which comprises a main material, the chemical formula of the main material comprising LiNi 0.93 Co 0.03 Mn 0.04 O2, and a coating layer is arranged on the surface of the main material, and the coating layer is lithium peroxide.

[0120] In step (1) of the preparation method of the high-nickel ternary material, the mass of the peroxide lithium peroxide is adjusted from 19.8 g to 10 g, and other conditions are the same as in Example 1.

[0121] Example 3

[0122] The present embodiment provides a high-nickel ternary material, which comprises a main material, the chemical formula of the main material comprising LiNi 0.93 Co 0.03 Mn 0.04 O2, and a coating layer is arranged on the surface of the main material, and the coating layer is lithium peroxide.

[0123] In step (1) of the preparation method of the high-nickel ternary material, the mass of the peroxide lithium peroxide is adjusted from 19.8 g to 39.7 g, and other conditions are the same as in Example 1.

[0124] Example 4

[0125] The present embodiment provides a high-nickel ternary material, which comprises a main material, the chemical formula of the main material comprising LiNi 0.93 Co 0.03 Mn 0.04 O2, and a coating layer is arranged on the surface of the main material, and the coating layer is lithium peroxide.

[0126] In step (1) of the preparation method of the high-nickel ternary material, the mass of the peroxide lithium peroxide is adjusted from 19.8 g to 100 g, and other conditions are the same as in Example 1.

[0127] Example 5

[0128] The embodiment provides a high-nickel ternary material, which comprises a main material, a chemical formula of the main material comprises LiNi 0.93 Co 0.03 Mn 0.04 O2, a surface of the main material is provided with a coating layer, and the coating layer is lithium peroxide.

[0129] In step (2) of the preparation method of the high-nickel ternary material, the mass of the lithium-containing compound lithium hydroxide monohydrate is adjusted to 251.65g, and other conditions are completely same as those in embodiment 1.

[0130] Embodiment 6

[0131] The embodiment provides a high-nickel ternary material, which comprises a main material, a chemical formula of the main material comprises LiNi 0.93 Co 0.03 Mn 0.04 O2, a surface of the main material is provided with a coating layer, and the coating layer is lithium peroxide.

[0132] In step (2) of the preparation method of the high-nickel ternary material, the mass of the lithium-containing compound lithium hydroxide monohydrate is adjusted to 2516.46g, and other conditions are completely same as those in embodiment 1.

[0133] Embodiment 7

[0134] The embodiment provides a high-nickel ternary material, which comprises a main material, a chemical formula of the main material comprises LiNi 0.93 Co 0.03 Mn 0.04 O2, a surface of the main material is provided with a coating layer, and the coating layer is lithium peroxide.

[0135] In step (3) of the preparation method of the high-nickel ternary material, the volume ratio of oxygen and ozone is adjusted to 94:6, and other conditions are completely same as those in embodiment 1.

[0136] Embodiment 8

[0137] The embodiment provides a high-nickel ternary material, which comprises a main material, a chemical formula of the main material comprises LiNi 0.93 Co 0.03 Mn 0.04 O2, a surface of the main material is provided with a coating layer, and the coating layer is lithium peroxide.

[0138] In step (3) of the preparation method of the high-nickel ternary material, the volume ratio of oxygen and ozone is adjusted to 98:2, and other conditions are completely same as those in embodiment 1.

[0139] Embodiment 9

[0140] The embodiment provides a high-nickel ternary material, which comprises a main material, a chemical formula of the main material comprising LiNi 0.93 Co 0.03 Mn 0.04 O2, and a cladding layer arranged on a surface of the main material, wherein the cladding layer is lithium peroxide.

[0141] In step (3) of the preparation method of the high-nickel ternary material, the volume ratio of oxygen and ozone is adjusted from 90:10 to 99:1, and other conditions are completely same as those in the embodiment 1.

[0142] Embodiment 10

[0143] The embodiment provides a high-nickel ternary material, which comprises a main material, a chemical formula of the main material comprising LiNi 0.93 Co 0.03 Mn 0.04 O2, and a cladding layer arranged on a surface of the main material, wherein the cladding layer is lithium peroxide.

[0144] In step (1) of the preparation method of the high-nickel ternary material, the peroxide is adjusted from lithium peroxide to sodium peroxide, and the mass of the peroxide is adjusted from 19.8 g to 33.6 g, and other conditions are completely same as those in the embodiment 1.

[0145] Comparative example 1

[0146] The embodiment provides a high-nickel ternary material, which comprises a main material, a chemical formula of the main material comprising LiNi 0.93 Co 0.03 Mn 0.04 O2.

[0147] The preparation method of the high-nickel ternary material does not perform step (2), directly performs step (3) on the main material LiNi 0.93 Co 0.03 Mn 0.04 O2 obtained in step (1), and other conditions are completely same as those in the embodiment 1.

[0148] Comparative example 2

[0149] The embodiment provides a high-nickel ternary material, which comprises a main material, a chemical formula of the main material comprising LiNi 0.93 Co 0.03 Mn 0.04 O2.

[0150] The preparation method of the high-nickel ternary material does not perform step (2) and step (3), and only uses the main material LiNi 0.93 Co 0.03 Mn0.04 O2, except for the above, the other conditions are exactly the same as in Example 1.

[0151] Comparative Example 3

[0152] This embodiment provides a high-nickel ternary material, including a main material, the chemical formula of which includes LiNi. 0.93 Co 0.03 Mn 0.04 O2;

[0153] In step (3) of the preparation method of the high-nickel ternary material, pure water is used instead of the lithium-containing aqueous solution. Except for the above, the other conditions are exactly the same as those in Example 1.

[0154] Comparative Example 4

[0155] This embodiment provides a high-nickel ternary material, including a main material, the chemical formula of which includes LiNi. 0.93 Co 0.03 Mn 0.04 O2;

[0156] The preparation method of the high-nickel ternary material does not perform steps (2) and (3), but only step (1), and no peroxide is used in step (1). Except for the above, the other conditions are exactly the same as those in Example 1.

[0157] The ternary materials obtained in the examples and comparative examples were tested:

[0158] Ⅰ. For example Figure 1 As shown, Example 1 is a polycrystalline lithium nickel cobalt manganese oxide with no other impurities on the surface. Because the water-washed lithium hydroxide coating is very uniform, its morphology did not change significantly after sintering in ozone. Figure 2 As shown, after water washing and ozone sintering treatment, the material is still lithium nickel cobalt manganese oxide with an α-NaFeO2 type layered structure, and the crystal structure has not changed significantly.

[0159] II. The mass content of LiOH, Li2CO3, and residual lithium was determined;

[0160] Specifically, 50g of ternary material was dispersed in 200mL of deionized water, stirred for 15min and then filtered. The filtrate was titrated with 0.1M hydrochloric acid solution in a potentiometric titrator. The mass content of LiOH, Li2CO3 and residual lithium was calculated based on the position of the abrupt peak.

[0161] III. Testing the degree of lithium-nickel mixing in ternary materials;

[0162] Specifically, HighScore was used to refine the XRD data of ternary materials to obtain lithium-nickel mixed data.

[0163] IV. Discharge capacity test and cycle performance test of the battery prepared from the ternary material;

[0164] Specifically, the prepared high-nickel ternary positive electrode material was used as an active material, acetylene black was used as a conductive agent, and polyvinylidene fluoride (PVDF) was used as a binder, and the mass ratio was 90:5:5, and an electrode sheet was prepared. The electrode sheet was used as a positive electrode, and a lithium sheet was used as a negative electrode, and a CR2430 type button cell was assembled in a glove box filled with high-purity argon.

[0165] The battery was tested by using a Wuhan Blue Test Instrument (CT2001A) to test the electrical performance: the first cycle capacity and the first cycle efficiency test conditions were 2.8-4.25V, 0.1C (1C=180mA / g) cycle 1; the discharge cycle test conditions were 2.8-4.25V, 0.1C cycle 2, and then 2.8-4.25V, 0.5C cycle 80.

[0166] The results are shown in Table 1.

[0167] Table 1

[0168]

[0169] In Table 1, " / " represents not tested.

[0170] As can be seen from Table 1:

[0171] The peroxide content used in Example 1 is suitable to reduce the lithium-nickel mixing degree of the material, the water washing capacity concentration is moderate, and the ozone concentration is high enough, so that the material has high capacity and good cycle performance, as shown in Table 1. Figure 3

[0172] Comparing Example 1 with Examples 2-4, it is found that the higher the amount of peroxide added, the lower the lithium-nickel mixing value of the material.

[0173] Comparing Example 1 with Examples 5-6, it is found that after the lithium hydroxide concentration is reduced in Example 5, the LiOH content is significantly reduced, the discharge capacity is also significantly reduced, and the cycle performance is also poor. After the lithium hydroxide concentration is increased in Example 6, the LiOH content is significantly increased, and the residual lithium content is also high, resulting in a low discharge capacity.

[0174] Comparing Example 1 with Examples 7-9, it is found that the discharge capacity is reduced after the ozone content is reduced, because the generated lithium peroxide on the surface of the material is reduced.

[0175] Comparing Example 1 with Example 10, it is found that in Example 10, the lithium peroxide in high-temperature sintering is replaced with sodium peroxide, because the sodium element will be washed away during the water washing process, resulting in excessive washing of the residual lithium on the surface of the material, thereby affecting the capacity development. ​

[0176] Comparing Example 1 with Comparative Examples 1-4, it is found that Comparative Example 1 has too much residual lithium due to the lack of water washing process, which affects the capacity. Comparative Example 2 has poor capacity and cycle performance due to the lack of any modification.

[0177] As can be seen from the above, by introducing peroxide in the high-temperature calcination process, the material lithium-nickel mixing degree can be effectively reduced, the water washing process can coat lithium-containing compounds on the surface of the material, and lithium peroxide can be further generated in the ozone-containing environment sintering to form a coating layer, thereby optimizing the material capacity and cycle performance. The high-nickel ternary positive electrode material prepared by the method of the present application has high capacity and good cycle performance, and is suitable for application in the field of lithium-ion batteries.

[0178] The above describes the preferred embodiments of the present application, but the present application is not limited to the specific details in the above-described embodiments, and various simple modifications can be made to the technical solutions of the present application within the technical concept of the present application, and these simple modifications all belong to the protection scope of the present application.

[0179] In addition, it should be noted that each specific technical feature described in the above specific embodiments can be combined in any appropriate manner without contradiction, and in order to avoid unnecessary repetition, the present application will not further describe various possible combinations.

[0180] In addition, various different embodiments of the present application can also be combined in any manner, as long as it does not deviate from the idea of the present application, and it should also be considered as disclosed by the present application.

Claims

1. A high-nickel ternary cathode material, characterized in that, comprising a main material, the main material comprising LiNi x Co y Mn z O2, wherein x≥0.6, y>0, z>0, x+y+z=1; a surface of the main material is provided with a coating layer, the coating layer comprising lithium peroxide; The preparation method of the high-nickel ternary positive electrode material comprises: (1) mixing a precursor Ni x Co y Mn z (OH)2, a lithium source and a peroxide, calcining to obtain a main material LiNi x Co y Mn z O2, wherein x≥0.6, y>0, z>0, and x+y+z=1. (2) mixing the obtained main material LiNi x Co y Mn z O2 with a lithium-containing aqueous solution to form a lithium hydroxide pre-coating layer on the surface of the main material LiNi x Co y Mn z O2, to obtain a pre-coated body; (3) performing heat treatment on the obtained pre-coated body in an ozone-containing atmosphere to convert the lithium hydroxide pre-coated layer into a lithium peroxide coated layer, thereby obtaining the high-nickel ternary positive electrode material; The ozone-containing atmosphere is a mixed atmosphere of ozone and oxygen. 2.The high-nickel ternary cathode material of claim 1, characterized in that, The main material is an ultrahigh-nickel ternary positive electrode material, and x>0.

9.

3. The method for preparing the high-nickel ternary cathode material of claim 1, characterized in that, The preparation method comprises: (1) mixing a precursor Ni x Co y Mn z (OH)2, a lithium source and a peroxide, and performing calcination to obtain a main material LiNi x Co y Mn z O2, wherein x≥0.6, y>0, z>0, and x+y+z=1. (2) mixing the obtained main material LiNi x Co y Mn z O2 with a lithium-containing aqueous solution to form a lithium hydroxide pre-coating layer on the surface of the main material LiNi x Co y Mn z O2, to obtain a pre-coated body; (3) performing heat treatment on the obtained pre-coated body in an ozone-containing atmosphere to convert the lithium hydroxide pre-coated layer into a lithium peroxide coated layer, thereby obtaining the high-nickel ternary positive electrode material.

4. The method for preparing the high-nickel ternary cathode material according to claim 3, characterized in that, In step (1), the precursor Ni x Co y Mn z The ratio of the molar amount of the precursor Ni(OH)2 to the molar amount of lithium element in the lithium source is 1:(1~1.2). 5.The method of claim 3, wherein the high-nickel ternary cathode material is prepared by the steps of: preparing a precursor by mixing a lithium source, a nickel source, a cobalt source, and an aluminum source; and performing a heat treatment on the precursor. In step (1), the lithium source comprises any one of lithium oxalate, lithium carbonate, lithium hydroxide monohydrate, lithium acetate or lithium citrate.

6. The method for preparing the high-nickel ternary cathode material according to claim 3, characterized in that, In step (1), the precursor Ni x Co y Mn z The ratio of the molar amount of the precursor Ni(OH)2to the molar amount of the peroxide is 1:(0.001-0.01). 7.The method of claim 3, wherein the high-nickel ternary cathode material is prepared by the steps of: preparing a precursor by mixing a lithium source, a nickel source, a cobalt source, and an aluminum source; and performing a heat treatment on the precursor. In step (1), the peroxide comprises any one of lithium peroxide, sodium peroxide, nickel peroxide, strontium peroxide or barium peroxide. 8.The method of claim 3, wherein the high-nickel ternary cathode material is prepared by the steps of: preparing a precursor by mixing a lithium source, a nickel source, a cobalt source, and an aluminum source; and performing a heat treatment on the precursor. In step (1), the temperature of the calcination is 700-1100°C, and the time is 10-20h. 9.The method of claim 3, wherein the high-nickel ternary cathode material is prepared by the steps of: preparing a precursor by mixing a lithium source, a nickel source, a cobalt source, and an aluminum source; and performing a heat treatment on the precursor. In step (2), the concentration of lithium in the lithium-containing aqueous solution is 0.5-5mol / L.

10. The method for preparing the high-nickel ternary cathode material according to claim 3, characterized in that, The lithium-containing aqueous solution and the main material LiNi x Co y Mn z The mass ratio of Li2CO3 to LiNi0.8Co0.15Al0.05O2 is (0.1-1):

1.

11. The method for preparing the high-nickel ternary cathode material according to claim 3, characterized in that, The method for preparing the lithium-containing aqueous solution in step (2) comprises adding a lithium-containing compound into water with a temperature of 0-40°C, and stirring at 100-300rpm for 2-20min.

12. The method for preparing the high-nickel ternary cathode material according to claim 11, characterized in that, The lithium-containing compound comprises at least one of lithium oxalate, lithium oxide, lithium hydroxide monohydrate, lithium acetate or lithium citrate. 13.The method of claim 3, wherein the high-nickel ternary cathode material is prepared by the steps of: preparing a precursor by mixing a lithium source, a nickel source, a cobalt source, and an aluminum source; and performing a heat treatment on the precursor. In step (2), the main material LiNi x Co y Mn z The mixing time of O2 and the lithium-containing aqueous solution is 10-60 min.

14. The method for preparing the high-nickel ternary cathode material according to claim 3, characterized in that, In step (2), the main material LiNi x Co y Mn z After mixing the Li2O2 with the lithium-containing aqueous solution, the mixed solution is centrifuged at 40-60 Hz for 0.5-1.5 h to obtain a centrifugate; the centrifugate is vacuum dried at 100-180 °C for 2-20 h, and then sieved through a 280-320 mesh screen to obtain undersize; the obtained undersize is used as the pre-coated body in step (3).

15. The method for preparing the high-nickel ternary cathode material according to claim 3, characterized in that, In step (3), the ozone-containing atmosphere contains ozone with a volume fraction of 1%-10%.

16. The method for preparing the high-nickel ternary cathode material according to claim 3, characterized in that, The temperature of the heat treatment is 200-400°C, and the time is 5-10h.

17. A positive electrode sheet characterized by comprising: The high-nickel ternary positive electrode material of claim 1 or 2.

18. A battery, characterized by The positive electrode sheet of claim 17.

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