A positive electrode material and a battery including the same

Abstract

The application belongs to the technical field of batteries, and particularly relates to a positive electrode material and a battery comprising the same. The positive electrode material comprises component 1 and a shell layer, the shell layer is coated on the surface of the component 1 to form a core-shell structure; the preparation raw material of the shell layer comprises a substance with a chemical formula of Ni 1+d Co 2‑d A e (OH) g (CO3) h and / or a substance with a chemical formula of Ni 1+d Co 2‑d A e O4; wherein 0<=d<=0.2, 0<=e<=0.01, 0<=g<=4, 0<=h<=2, and g and h are not 0 at the same time; A is one or more of Al, Mg, W, Nb and Mo. The positive electrode material provided by the application has good interface stability and cycle stability under a high-voltage system, and can effectively improve the high-temperature cycle performance and high-temperature storage performance of the battery under the high-voltage system after being assembled into the battery.

Description

Technical Field

[0001] This invention belongs to the field of battery technology, specifically relating to a positive electrode material and a battery including the positive electrode material. Background Technology

[0002] Electrons travel through the world carrying all sorts of information, yet batteries, which provide resting places and energy for their movement, have consistently fallen short of meeting human needs. Lithium-ion batteries, currently the mainstream solution, rely heavily on their internal components to influence core performance indicators such as energy density, safety, and lifespan, especially the cathode material. There is a constant pursuit of cathode materials with superior performance. For lithium cobalt oxide, higher capacity and energy density stem from higher voltage, allowing more active lithium to participate in the energy transfer process. However, further lithium intercalation and deintercalation significantly reduces the material's stability. The more lithium is intercalated and deintercalated, the greater the need for new technologies to improve material stability. Compared to bulk structures, surface structures must withstand higher voltages and corrosion stresses, making interfacial stability an increasingly important concern. Summary of the Invention

[0003] Studies have found that surface coating can improve the stability of cathode materials, stabilize the internal charge balance, reduce the activity of surface cobalt, or inhibit the destructive effects of highly active cobalt ions on the chemical system, especially the electrolyte. Currently, most commonly used oxides for coating lack the ability to transport lithium ions, and the fast ion conductors used in coating are prone to decomposition under high voltage, thus reducing the material's stability. Furthermore, the bonding between the fast ion conductor and the substrate material is generally a physical contact, making it difficult to form a tightly bonded solid solution interface. Conventional cobalt oxide coatings are also relatively close to the intrinsic properties of the material, and metal dissolution is difficult to suppress.

[0004] To address the aforementioned problems, the present invention provides a positive electrode material and a battery comprising the positive electrode material. The positive electrode material comprises component 1 and component 2. Component 1 is a matrix material, and component 2 is a fast ion conductor material with good stability. It can improve the surface stability of component 1 under high voltage and effectively inhibit electrolyte corrosion.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] A positive electrode material, the positive electrode material comprising component 1 and component 2;

[0007] Component 1 is a chemical formula Li x M 1-y Me y O2 substances, where M = Co 1-a-b Al a Zb Me is one or more of Ni, Ti, Y, W, La, Zr, and Nb, and Z is one or more of Mg, W, Nb, and Ti; 0.97≤x≤1.06, 0≤y≤0.1, 0.03≤a≤0.05, and 0.0005≤b≤0.01;

[0008] Component 2 is a chemical formula Li j Ni k Co l A m D n The substance of O2, wherein 0≤j≤1, 0≤k≤0.5, 0≤l≤1.5, 0≤m≤0.01, 0≤n≤0.01, and k and l are not simultaneously 0, A is one or more of Al, Mg, W, Nb, and Mo, and D is one or more of Na, Ti, Li, Al, Mg, Zr, Y, La, Mo, Ce, and Nb.

[0009] According to an embodiment of the present invention, component 2 coats the surface of component 1; exemplaryly, the coating may be partial or complete. Preferably, component 2 coats the surface of component 1 to form a coating layer with a thickness of 10 nm to 100 nm.

[0010] According to an embodiment of the present invention, the positive electrode material further includes component 3, wherein component 3 is a chemical formula Li j’ Ni k Co l A m D n O2 is a substance in which k, l, m, n, A, and D are defined as described above, j' <j。

[0011] According to an embodiment of the present invention, component 3 coats the surface of component 2; exemplaryly, the coating may be partial or complete. Preferably, component 3 coats the surface of component 2 to form a coating layer with a thickness of 2 nm to 10 nm.

[0012] According to an embodiment of the present invention, the positive electrode material further includes component 4, wherein the chemical formula of component 4 is Li x M 1-y Me y O2 is a substance in which M = Ni 1-a-b Al a Z b The definitions of Me, Z, x, y, a, and b are as described above.

[0013] According to an embodiment of the present invention, component 4 is located between component 2 and component 1.

[0014] According to an embodiment of the present invention, the Ni content in component 4 exhibits a gradient distribution. This gradient distribution means that the Ni content gradually decreases from the surface layer to the core.

[0015] According to an embodiment of the present invention, the raw materials for preparing component 2, optionally component 3, and optionally component 4 include Ni 1+d Co 2-d A e (OH) g (CO3) h The substance and / or chemical formula is Ni 1+d Co 2-d A e The substance of O4; wherein, 0≤d≤0.2, 0≤e≤0.01, 0≤g≤4, 0≤h≤2, and g and h are not both 0; A is one or more of Al, Mg, W, Nb, and Mo.

[0016] According to an embodiment of the present invention, the raw materials for preparing component 2, optionally component 3, and optionally component 4 further include chemical formula D. f O i The substance is a mixture of Na, Ti, Li, Al, Mg, Zr, Y, La, Mo, Ce, and Nb, where D is one or more of Na, Ti, Li, Al, Mg, Zr, Y, La, Mo, Ce, and Nb, and f and i satisfy the chemical valence equilibrium of element D.

[0017] According to an embodiment of the present invention, component 2, optionally component 3, and optionally component 4 are of the chemical formula Ni. 1+ d Co 2-d A e (OH) g (CO3) h The substance and chemical formula are D f O i The substance is prepared by sintering; or, component 2, optionally component 3 and optionally component 4 are substances with the chemical formula Ni. 1+d Co 2-d A e The substance and chemical formula of O4 is D. f O i The substance is prepared by sintering; or, component 2, optionally component 3 and optionally component 4 are substances with the chemical formula Ni. 1+d Co 2-d A e (OH) g (CO3) h The substance with the chemical formula Ni 1+d Co 2-d A e The substance and chemical formula of O4 is D. f Oi The substance is prepared by sintering.

[0018] According to an embodiment of the present invention, the sintering temperature is 500℃ to 900℃ (e.g., 500℃, 550℃, 600℃, 650℃, 700℃, 750℃, 800℃, 850℃ or 900℃), the sintering time is 6 to 10 hours (e.g., 6 hours, 7 hours, 8 hours, 9 hours or 10 hours), and the sintering atmosphere is an air atmosphere.

[0019] According to an embodiment of the present invention, the chemical formula is Ni 1+d Co 2-d A e (OH) g (CO3) h After the substance is coated on the surface of component 1, it will further shrink and recombine during sintering, undergoing various phase structure changes. Specifically, high temperature will cause Ni... 1+d Co 2-d A e (OH) g (CO3) h Remove C or H to form Ni oxide. 1+d Co 2-d A e O4, and at the same time, a large amount of residual alkali (main component lithium carbonate, secondary component lithium hydroxide) will remain on the surface of component 1. This residual alkali will form lithium oxide at high temperature, and the lithium oxide will react with the formed oxide Ni. 1+d Co 2-d A e O4, D f O i The reaction produces a product with the chemical formula Li j Ni k Co l A m D n The substance containing O2, i.e., component 2. Alternatively, the chemical formula is Ni. 1+d Co 2-d A e During the sintering process after O4 is coated on the surface of component 1, it will directly react with lithium oxide and D formed at high temperature by residual alkali. f O i The reaction produces a product with the chemical formula Li j Ni k Co l A m D n The substance containing O2 is component 2.

[0020] According to an embodiment of the present invention, since no additional lithium source is added during the preparation of the cathode material, residual alkali may exist on the surface of component 1. Under the action of the residual alkali, the chemical formula Ni 1+d Co 2-d A e (OH) g (CO3) h The substance and / or chemical formula is Ni 1+d Co 2-d A e The O4-containing material also forms a 2nm–10nm thick lithium-deficient spinel phase structure on the surface of component 1, which is component 3. Component 3 has a low Li content but exhibits high stability, reducing electrolyte corrosion. Furthermore, this spinel phase structure possesses excellent electrical conductivity, with a powder conductivity of 10⁻⁶. -2 The S / cm ratio is much higher than that of component 1 itself, and the nanostructure also has sufficient ion conduction capacity, so it will not reduce the lithium ion diffusion of the material itself.

[0021] According to an embodiment of the present invention, the chemical formula is Ni 1+d Co 2-d A e (OH) g (CO3) h The substance and / or chemical formula is Ni 1+d Co 2-d A e The Ni element in the O4 material may also diffuse uniformly to the surface of component 1, exhibiting gradient doping characteristics. This Ni diffusion can effectively suppress the H1-3 phase transition under high voltage (i.e., the high delithiation state of the material). That is, a stable solid solution interface layer, i.e., component 4, can be formed between component 2 and component 1. This solid solution interface layer is based on the Li matrix. x M 1-y Me y Gradient doped layers are formed when Co in O2 is replaced by Ni.

[0022] According to an embodiment of the present invention, d is 0, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19 or 0.2.

[0023] According to an embodiment of the present invention, e is 0, 0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.08, 0.009 or 0.01.

[0024] According to an embodiment of the present invention, g is 0, 1, 2, 3 or 4.

[0025] According to an embodiment of the present invention, h is 0, 1 or 2.

[0026] According to an embodiment of the present invention, j is 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or 1.0.

[0027] According to an embodiment of the present invention, k is 0.1, 0.2, 0.3, 0.4, or 0.5.

[0028] According to the embodiments of the present invention, l is 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5.

[0029] According to an embodiment of the present invention, m is 0, 0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.08, 0.009 or 0.01.

[0030] According to an embodiment of the present invention, n is 0, 0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.08, 0.009 or 0.01.

[0031] According to an embodiment of the present invention, x is 0.97, 0.98, 0.99, 1, 1.01, 1.02, 1.03, 1.04, 1.05, or 1.06.

[0032] According to an embodiment of the present invention, y is 0, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, or 0.1.

[0033] According to the embodiments of the present invention, a is 0.03, 0.031, 0.032, 0.033, 0.034, 0.035, 0.036, 0.037, 0.038, 0.039, 0.04, 0.041, 0.042, 0.043, 0.044, 0.045, 0.046, 0.047, 0.048, 0.049, or 0.05.

[0034] According to an embodiment of the present invention, b is 0.0005, 0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.08, 0.009, or 0.01.

[0035] According to an embodiment of the present invention, the chemical formula is Ni 1+d Co 2-d Ae (OH) g (CO3) h The substance is a secondary particle formed from the aggregation of primary particles. The chemical formula Ni is used to form this. 1+d Co 2-d A e (OH) g (CO3) h The primary particle size of the substance is 30 nm to 100 nm, for example, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, or 100 nm. The chemical formula is Ni. 1+d Co 2-d A e (OH) g (CO3) h The Dv50 of the substance is 500nm to 1000nm, for example, 500nm, 600nm, 700nm, 800nm, 900nm or 1000nm.

[0036] According to an embodiment of the present invention, the chemical formula is Ni 1+d Co 2-d A e The Dv50 of O4 is 500nm to 1000nm, for example, 500nm, 600nm, 700nm, 800nm, 900nm or 1000nm.

[0037] According to an embodiment of the present invention, the mass of component 1 accounts for 96 wt% to 99.5 wt% of the total mass of the cathode material, for example, 96 wt%, 97 wt%, 98 wt%, 99 wt% or 99.5 wt%.

[0038] According to an embodiment of the present invention, the mass of component 2 accounts for 0.5wt% to 4wt% of the total mass of the cathode material, for example, 0.5wt%, 1wt%, 1.5wt%, 2wt%, 2.5wt%, 3wt%, 3.5wt%, or 4wt%.

[0039] According to an embodiment of the present invention, the mass of component 3 accounts for 0 wt% to 4 wt% of the total mass of the cathode material, for example, 0 wt%, 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, and 1 wt%.

[0040] According to an embodiment of the present invention, the mass of component 4 accounts for 0 wt% to 1 wt% of the total mass of the cathode material, for example, 0 wt%, 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, and 1 wt%.

[0041] According to an embodiment of the present invention, the Dv50 of the positive electrode material is 15μm to 20μm.

[0042] The present invention also provides a method for preparing the above-mentioned cathode material, the method comprising the following steps:

[0043] (1) Prepare a chemical formula Ni 1+d Co 2-d A e (OH) g (CO3) h The substance and / or chemical formula is Ni 1+d Co 2-d A e The substance of O4, wherein 0≤d≤0.2, 0≤e≤0.01, 0≤g≤4, 0≤h≤2, and g and h are not simultaneously 0; A is one or more of Al, Mg, W, Nb, and Mo;

[0044] (2) Prepare a chemical formula Li x M 1-y Me y O2 substances, where M = Co 1-a-b Al a Z b Me is one or more of Ni, Ti, Y, W, La, Zr, and Nb, and Z is one or more of Mg, W, Nb, and Ti; 0.97≤x≤1.06, 0≤y≤0.1, 0.03≤a≤0.05, and 0.0005≤b≤0.01;

[0045] (3) The chemical formula of step (1) is Ni 1+d Co 2-d A e (OH) g (CO3) h The substance and / or chemical formula is Ni 1+d Co 2- d A e The substance and chemical formula of O4 is D. f O i The chemical formula of the substance and step (2) is Li x M 1-y Me yThe positive electrode material is prepared by mixing and sintering O2 with other substances, wherein D is one or more of Na, Ti, Li, Al, Mg, Zr, Y, La, Mo, Ce, and Nb, and f and i satisfy the chemical valence equilibrium of element D.

[0046] According to an embodiment of the present invention, in step (1), the chemical formula is Ni 1+d Co 2-d A e (OH) g (CO3) h The substance is prepared by the following method:

[0047] Soluble cobalt salt, soluble nickel salt, and a soluble salt containing element A are dissolved in a solvent, and sodium hexametaphosphate is added to obtain a mixed system. Sodium hydroxide and / or sodium carbonate are added to the mixed system as precipitants to carry out a co-precipitation reaction, yielding a product with the chemical formula Ni. 1+d Co 2-d A e (OH) g (CO3) h The substance.

[0048] According to an embodiment of the present invention, the solvent is one or more of deionized water, methanol, and ethanol.

[0049] According to an embodiment of the present invention, the molar concentration of the precipitant solution is 0.1 to 3 mol / L. It should be noted that before adding the precipitant to the mixed solution, the precipitant solution can be pre-prepared. The solvent used to prepare the precipitant solution can be one or more of deionized water, methanol, and ethanol.

[0050] According to an embodiment of the present invention, the molar concentration of the complexing agent solution is 0.1–3 mol / L, and the complexing agent used for the co-precipitation reaction is one or more of ammonia, ammonium carbonate, and ammonium bicarbonate. It should be noted that before adding the complexing agent to the mixed solution, the complexing agent solution can be prepared by means of a solvent such as deionized water, methanol, and ethanol.

[0051] According to an embodiment of the present invention, the pH of the coprecipitation reaction is 6 to 8, the temperature is 25°C to 85°C, and the time is 24h to 36h.

[0052] According to an embodiment of the present invention, the molar ratio of Ni, Co and A in the soluble cobalt salt, the soluble nickel salt and the soluble salt containing element A is (1+d):(2-d):e.

[0053] According to an embodiment of the present invention, a precipitate (chemical formula Ni) is used. 1+d Co2-d A e (OH) g (CO3) h The total theoretical mass of the substance is taken as the mass fraction of the sodium hexametaphosphate, which accounts for 0.01 to 0.5 wt% of the total mass.

[0054] According to an embodiment of the present invention, sodium tungstate may also be added to the mixed system.

[0055] According to an embodiment of the present invention, a precipitate (chemical formula Ni) is used. 1+d Co 2-d A e (OH) g (CO3) h The total theoretical mass of the substance is taken as the mass fraction of the sodium tungstate, which accounts for 0 to 0.5 wt% of the total mass.

[0056] According to an embodiment of the present invention, in step (1), the chemical formula is Ni 1+d Co 2-d A e The substance containing O4 is prepared by the following method:

[0057] The chemical formula Ni 1+d Co 2-d A e (OH) g (CO3) h The substance was sintered in air at 500–700°C for 8–16 hours to prepare the substance with the chemical formula Ni. 1+d Co 2-d A e O4 is a substance.

[0058] According to an embodiment of the present invention, in step (2), the chemical formula is Li x M 1-y Me y O2 is prepared by the following method:

[0059] Lithium carbonate, (Co) 1-a Al a )3O4 and Z-containing oxides were sintered in air at a temperature of 900–1100 °C for 8–16 h.

[0060] According to an embodiment of the present invention, lithium carbonate, (Co) 1-a Al a The molar ratio of Li:Co:Z in 3O4 and Z-containing oxides is 1:(1-ab):b.

[0061] According to an embodiment of the present invention, in step (3), the mixing is, for example, ball milling, with a ball milling speed of 150 r / min to 300 r / min.

[0062] According to an embodiment of the present invention, in step (3), the mixing time is 2 to 4 hours.

[0063] According to an embodiment of the present invention, in step (3), the chemical formula of step (1) is Ni. 1+d Co 2-d A e (OH) g (CO3) h The substance and / or chemical formula is Ni 1+d Co 2-d A e The substance and chemical formula of O4 is D. f O i The sum of the masses of the substances and the chemical formula of step (2) is Li x M 1-y Me y The mass ratio of O2 to other substances is 0.5–5:95–99.5.

[0064] According to an embodiment of the present invention, in step (3), the sintering temperature is 500℃~900℃ (e.g., 500℃, 550℃, 600℃, 650℃, 700℃, 750℃, 800℃, 850℃ or 900℃), the sintering time is 6~10 hours (e.g. 6 hours, 7 hours, 8 hours, 9 hours or 10 hours), and the sintering atmosphere is an air atmosphere.

[0065] The present invention also provides a positive electrode sheet, wherein the positive electrode sheet comprises the above-described positive electrode material.

[0066] According to an embodiment of the present invention, the positive electrode sheet includes a positive current collector and a positive active material layer coated on one or both surfaces of the positive current collector, wherein the positive active material layer includes a positive electrode material, a conductive agent, and a binder.

[0067] According to an embodiment of the present invention, the mass percentage of each component in the positive electrode active material layer is: 80-99.8 wt% of positive electrode material, 0.1-10 wt% of conductive agent, and 0.1-10 wt% of binder.

[0068] Preferably, the mass percentage of each component in the positive electrode active material layer is: 90-99.6 wt% positive electrode material, 0.2-5 wt% conductive agent, and 0.2-5 wt% binder.

[0069] According to an embodiment of the present invention, the conductive agent is selected from at least one of conductive carbon black, acetylene black, Ketjen black, conductive graphite, conductive carbon fiber, carbon nanotubes, metal powder, and carbon fiber.

[0070] According to an embodiment of the present invention, the adhesive is selected from at least one of sodium carboxymethyl cellulose, styrene-butadiene latex, polytetrafluoroethylene, and polyethylene oxide.

[0071] According to an embodiment of the present invention, the compaction density of the positive electrode sheet is 4.2 g / cm³. 3 ~4.35g / cm 3 .

[0072] The present invention also provides a battery comprising the above-described positive electrode material, or the battery comprising the above-described positive electrode sheet.

[0073] According to an embodiment of the present invention, the battery further includes a negative electrode, a separator, and an electrolyte.

[0074] According to an embodiment of the present invention, the electrolyte comprises an organic solvent, a conductive lithium salt, and additives.

[0075] According to an embodiment of the present invention, the organic solvent is selected from at least one of cyclic carbonates and at least one of linear carbonates and linear carboxylic acid esters.

[0076] According to an embodiment of the present invention, the conductive lithium salt is selected from at least one of lithium hexafluorophosphate, lithium bis(fluorosulfonyl)imide, and lithium bis(trifluoromethanesulfonyl)imide.

[0077] According to an embodiment of the present invention, the additive is selected from at least one of nitrile compounds, vinylene carbonate, and 1,3-propenesulfonate lactone.

[0078] According to an embodiment of the present invention, the negative electrode active material in the negative electrode sheet is selected from at least one of artificial graphite, natural graphite, hard carbon, mesophase carbon microspheres, lithium titanate, silicon carbide, and silicon suboxide.

[0079] According to an embodiment of the present invention, the diaphragm is selected from polypropylene substrate diaphragms, such as adhesive-coated polypropylene diaphragms coated with ceramics on one or both sides of a polypropylene substrate.

[0080] Beneficial effects:

[0081] This invention provides a positive electrode material and a battery comprising the positive electrode material. Specifically, this invention uses a material with the chemical formula Ni. 1+d Co 2-d A e (OH) g (CO3) h The substance and / or chemical formula is Ni 1+dCo 2-d A e O4 is used as a raw material for preparing the shell layer. After sintering, this raw material can form component 2, and optionally components 3 and 4, on the surface of component 1. The cathode material provided by this invention exhibits good interfacial stability and cycle stability under high voltage systems. When assembled into a battery, it can effectively improve the high-temperature cycle performance and high-temperature storage performance of the battery under high voltage systems. Attached Figure Description

[0082] Figure 1 Nickel-cobalt oxide NiCo2W in Example 1 0.0005 SEM image of O4.

[0083] Figure 2 Scanning SEM image of the cathode material in Example 1.

[0084] Figure 3 XRD pattern of nickel-cobalt oxide NiCo2O4 in Example 2.

[0085] Figure 4 CP cross-sectional view of the cathode material in Example 1.

[0086] Figure 5 Cross-sectional Ni energy spectrum of the cathode material in Example 1. Detailed Implementation

[0087] The present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are merely illustrative and explanatory of the present invention and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are covered within the scope of protection intended by the present invention.

[0088] Unless otherwise specified, the experimental methods used in the following examples are conventional methods; unless otherwise specified, the reagents and materials used in the following examples are commercially available.

[0089] Example 1:

[0090] (1) Preparation of nickel-cobalt oxide: Cobalt sulfate and nickel sulfate were prepared in a molar ratio of Co:Ni = 2:1, and a 2 mol / L sodium hydroxide solution was prepared. Precipitation was carried out in a base solution (deionized water) at 50℃ and pH = 8. 0.02 wt% sodium hexametaphosphate and 0.05 wt% sodium tungstate were added by weight percentage. The feed rate was kept constant at 50 ml / h. After the feed was completed, the reaction continued for 10 h. The precipitate was washed with water, removed, and dried in a 120℃ oven. It was then crushed using a ball mill at 250 rpm to obtain a nickel-cobalt metal salt (chemical formula NiCo2O4W) with a Dv50 of 600 nm. 0.0005(OH)4) It is then placed in a muffle furnace under air atmosphere and sintered at 600℃ for 8 hours to obtain nickel-cobalt oxide NiCo2W. 0.0005 O4, its appearance is as follows Figure 1 As shown;

[0091] (2) Preparation of Li x M 1-y Me y O2: Li2CO3, (Co) 0.97 Al 0.03 Li3O4 and La2O3 were weighed and mixed uniformly according to a molar ratio of Li:Co:La of 1.05:1:0.0005. The mixture was placed in a muffle furnace under air atmosphere and sintered at 1050℃ for 12 hours. After natural cooling, the mixture was crushed, ground, and sieved to obtain doped lithium cobalt oxide (Li3O4). 1.02 Co 0.97 Al 0.03 La 0.0005 O2;

[0092] (3) Preparation of the final cathode material: Subsequently, the above-mentioned nickel-cobalt oxide NiCo2W 0.0005 O4, doped lithium cobalt oxide Li from step (2) 1.02 Co 0.97 Al 0.03 La 0.0005 O2, aluminum oxide, magnesium oxide, and titanium oxide were mixed using a high-performance mixer at a speed of 2000 rpm. 1000g of the mixture contained 20g of nickel-cobalt oxide, 5g of aluminum oxide, 3g of titanium oxide, and 3g of magnesium oxide. The mixture was then sintered at 800℃ for 8 hours in an air atmosphere. After natural cooling, the mixture was crushed, ground, and sieved to obtain the cathode material, the morphology of which is shown below. Figure 2 As shown, the cathode material was fabricated into a battery and relevant tests were conducted.

[0093] Example 2:

[0094] (1) Preparation of nickel-cobalt oxide: Cobalt sulfate and nickel sulfate were prepared in a molar ratio of Co:Ni = 2:1, and a 2 mol / L sodium hydroxide solution was prepared. Precipitation was carried out in a base solution (deionized water) at 50℃ and pH = 8. 0.02 wt% sodium hexametaphosphate was added at a constant feed rate of 50 ml / h. After the feed was completed, the reaction continued for 10 h. The precipitate was washed with water, removed, and dried in a 120℃ forced-air oven. It was then crushed using a ball mill at 250 rpm to obtain a nickel-cobalt metal salt (chemical formula NiCo2O4(OH)4) with a Dv50 of 600 nm. This was then sintered in a muffle furnace under air atmosphere at 600℃ for 8 h to obtain nickel-cobalt oxide NiCo2O4. Its XRD pattern is shown below. Figure 3 As shown;

[0095] (2) Same as Example 1;

[0096] (3) Preparation of the final cathode material: Subsequently, the above-mentioned nickel-cobalt oxide NiCo2O4 and the doped lithium cobalt oxide Li from step (2) are combined. 1.02 Co 0.97 Al 0.03 La 0.0005 O2, aluminum oxide, magnesium oxide, and titanium oxide are mixed using a high-performance mixer at a speed of 2000 r / min. 1000g of the mixture contains 20g of nickel-cobalt oxide, 5g of aluminum oxide, 3g of titanium oxide, and 3g of magnesium oxide. The mixture is then sintered at 800℃ for 8 hours in an air atmosphere. After natural cooling, the mixture is crushed, ground, and sieved to obtain the cathode material. This cathode material is then used to prepare a battery and subjected to relevant tests.

[0097] Example 3:

[0098] (1) Prepare solutions of cobalt sulfate and nickel sulfate at a molar ratio of Co:Ni = 2:1, and prepare a sodium hydroxide solution with a molar concentration of 2 mol / L. The precipitation reaction is carried out in a base solution (deionized water) at 50℃ and pH = 8. Add 0.02 wt% sodium hexametaphosphate and 0.05 wt% sodium tungstate by weight percentage. After the feed rate is kept constant at 50 ml / h, continue the reaction for 10 h. Wash the precipitate with water, remove it, and dry it in a forced-air oven at 120℃. Then, crush it using a ball mill at a speed of 250 rpm to obtain a nickel-cobalt metal salt (chemical formula NiCo2O4W) with a Dv50 of 600 nm. 0.0005 (OH)4);

[0099] (2) Same as Example 1;

[0100] (3) Preparation of the final cathode material: The nickel-cobalt metal salt, the doped lithium cobalt oxide from step (2), aluminum oxide, magnesium oxide and titanium oxide are then mixed using an ultra-high-power mixer at a speed of 2000 r / min. 1000 g of the mixture includes 20 g of nickel-cobalt metal salt, 5 g of aluminum oxide, 3 g of titanium oxide and 3 g of magnesium oxide. The mixture is then sintered at a temperature of 800 °C for 8 hours in an air atmosphere. After natural cooling, the cathode material is obtained by crushing, grinding and sieving. The cathode material is then used to prepare a battery and is subjected to relevant tests.

[0101] Example 4:

[0102] (1) Same as Example 3;

[0103] (2) Same as Example 1;

[0104] (3) Preparation of the final cathode material: The nickel-cobalt metal salt, the doped lithium cobalt oxide from step (2), aluminum oxide, magnesium oxide, yttrium oxide and titanium oxide are then mixed using an ultra-high-power mixer at a speed of 2000 r / min. 1000 g of the mixture includes 20 g of nickel-cobalt metal salt, 5 g of aluminum oxide, 3 g of titanium oxide, 3 g of yttrium oxide and 3 g of magnesium oxide. The mixture is then sintered at a temperature of 800 °C for 8 hours in an air atmosphere. After natural cooling, the cathode material is obtained by crushing, grinding and sieving. The cathode material is then used to prepare a battery and is subjected to relevant tests.

[0105] Example 5:

[0106] (1) Same as Example 3;

[0107] (2) Same as Example 1;

[0108] (3) Preparation of the final cathode material: The above nickel-cobalt metal salt, the doped lithium cobalt oxide, aluminum oxide, magnesium oxide, niobium oxide and titanium oxide from step (2) are then mixed using an ultra-high-power mixer at a speed of 2000 r / min. 1000 g of the mixture includes 20 g of nickel-cobalt metal salt, 5 g of aluminum oxide, 3 g of titanium oxide, 3 g of niobium oxide and 3 g of magnesium oxide. The mixture is then sintered at a temperature of 800 °C for 8 hours in an air atmosphere. After natural cooling, the cathode material is obtained by crushing, grinding and sieving. The cathode material is then used to prepare a battery and is subjected to relevant tests.

[0109] Example 6:

[0110] (1) Same as Example 3;

[0111] (2) Same as Example 1;

[0112] (3) Preparation of the final cathode material: The nickel-cobalt metal salt, the doped lithium cobalt oxide, aluminum oxide, magnesium oxide, niobium oxide and titanium oxide from step (2) are then mixed using an ultra-high-power mixer at a speed of 2000 r / min. 1000 g of the mixture includes 10 g of nickel-cobalt metal salt, 5 g of aluminum oxide, 3 g of titanium oxide, 3 g of niobium oxide and 3 g of magnesium oxide. The mixture is then sintered at a temperature of 800 °C for 8 hours in an air atmosphere. After natural cooling, the cathode material is obtained by crushing, grinding and sieving. The cathode material is then used to prepare a battery and is subjected to relevant tests.

[0113] Example 7:

[0114] (1) Same as Example 3;

[0115] (2) Same as Example 1;

[0116] (3) Preparation of the final cathode material: The above nickel-cobalt metal salt, the doped lithium cobalt oxide, aluminum oxide, magnesium oxide, niobium oxide and titanium oxide from step (2) are then mixed using an ultra-high-power mixer at a speed of 2000 r / min. 1000 g of the mixture includes 30 g of nickel-cobalt metal salt, 5 g of aluminum oxide, 3 g of titanium oxide, 3 g of niobium oxide and 3 g of magnesium oxide. The mixture is then sintered at a temperature of 800 °C for 8 hours in an air atmosphere. After natural cooling, the cathode material is obtained by crushing, grinding and sieving. The cathode material is then used to prepare a battery and is subjected to relevant tests.

[0117] Example 8:

[0118] (1) Same as Example 3;

[0119] (2) Same as Example 1;

[0120] (3) Preparation of the final cathode material: The above nickel-cobalt metal salt, the doped lithium cobalt oxide, aluminum oxide, magnesium oxide, niobium oxide, titanium oxide and yttrium oxide from step (2) are then mixed using an ultra-high-power mixer at a speed of 2000 r / min. 1000 g of the mixture includes 20 g of nickel-cobalt metal salt, 3 g of aluminum oxide, 3 g of magnesium oxide, 2 g of niobium oxide, 2 g of titanium oxide and 2 g of yttrium oxide. The mixture is then sintered at a temperature of 800 °C for 8 hours in an air atmosphere. After natural cooling, the cathode material is obtained by crushing, grinding and sieving. The cathode material is then used to prepare a battery and is subjected to relevant tests.

[0121] Example 9:

[0122] The lithium cobalt oxide cathode material was prepared using the same method as in Example 1, except that in step (1), the sodium hydroxide used for precipitation was replaced with sodium carbonate, and the resulting metal salt was a carbonate.

[0123] Example 10:

[0124] The lithium cobalt oxide cathode material was prepared using the same method as in Example 3, except that in step (1), the sodium hydroxide used for precipitation was replaced with sodium carbonate, and the resulting metal salt was a carbonate.

[0125] Example 11:

[0126] (1) Same as Example 10;

[0127] (2) Same as Example 1;

[0128] (3) Preparation of the final cathode material: The above nickel cobalt metal salt, the doped lithium cobalt oxide from step (2), aluminum oxide, magnesium oxide, yttrium oxide and titanium oxide are then mixed using an ultra-high-power mixer at a speed of 2000 r / min. 1000 g of the mixture includes 20 g of nickel cobalt metal salt, 5 g of aluminum oxide, 3 g of titanium oxide, 10 g of yttrium oxide and 3 g of magnesium oxide. The mixture is then sintered at a temperature of 800 °C for 8 hours in an air atmosphere. After natural cooling, the cathode material is obtained by crushing, grinding and sieving. The cathode material is then used to prepare a battery and is subjected to relevant tests.

[0129] Example 12:

[0130] (1) Same as Example 10;

[0131] (2) Same as Example 1;

[0132] (3) Preparation of the final cathode material: The above nickel-cobalt metal salt, the doped lithium cobalt oxide, aluminum oxide, magnesium oxide, niobium oxide and titanium oxide from step (2) are then mixed using an ultra-high-power mixer at a speed of 2000 r / min. 1000 g of the mixture includes 20 g of nickel-cobalt metal salt, 5 g of aluminum oxide, 3 g of titanium oxide, 2 g of niobium oxide and 3 g of magnesium oxide. The mixture is then sintered at a temperature of 800 °C for 8 hours in an air atmosphere. After natural cooling, the cathode material is obtained by crushing, grinding and sieving. The cathode material is then used to prepare a battery and is subjected to relevant tests.

[0133] Example 13:

[0134] (1) Same as Example 10;

[0135] (2) Same as Example 1;

[0136] (3) Preparation of the final cathode material: The nickel-cobalt metal salt, the doped lithium cobalt oxide from step (2), aluminum oxide, magnesium oxide and titanium oxide are then mixed using an ultra-high-power mixer at a speed of 2000 r / min. 1000 g of the mixture contains 10 g of nickel-cobalt metal salt, 5 g of aluminum oxide, 3 g of titanium oxide and 3 g of magnesium oxide. The mixture is then sintered at a temperature of 800 °C for 8 hours in an air atmosphere. After natural cooling, the cathode material is obtained by crushing, grinding and sieving. The cathode material is then used to prepare a battery and is subjected to relevant tests.

[0137] Example 14:

[0138] (1) Same as Example 10;

[0139] (2) Same as Example 1;

[0140] (3) Preparation of the final cathode material: The above nickel cobalt metal salt, the doped lithium cobalt oxide from step (2), aluminum oxide, magnesium oxide and titanium oxide are then mixed using an ultra-high-power mixer at a speed of 2000 r / min. 1000 g of the mixture includes 30 g of nickel cobalt metal salt, 5 g of aluminum oxide, 3 g of titanium oxide and 3 g of magnesium oxide. The mixture is then sintered at a temperature of 800 °C for 8 hours in an air atmosphere. After natural cooling, the cathode material is obtained by crushing, grinding and sieving. The cathode material is then used to prepare a battery and is subjected to relevant tests.

[0141] Example 15:

[0142] (1) Same as Example 10;

[0143] (2) Same as Example 1;

[0144] (3) Preparation of the final cathode material: The nickel-cobalt metal salt, the doped lithium cobalt oxide, aluminum oxide, magnesium oxide, yttrium oxide, niobium oxide and titanium oxide from step (2) are then mixed using an ultra-high-power mixer at a speed of 2000 r / min. 1000 g of the mixture contains 20 g of nickel-cobalt metal salt, 3 g of aluminum oxide, 2 g of titanium oxide, 2 g of niobium oxide, 3 g of magnesium oxide and 2 g of yttrium oxide. The mixture is then sintered at a temperature of 800 °C for 8 hours in an air atmosphere. After natural cooling, the cathode material is obtained by crushing, grinding and sieving. The cathode material is then used to prepare a battery and is subjected to relevant tests.

[0145] The variations in the embodiments mainly revolve around the synergistic effect of the modified coating with other oxides, and its effect as a base coating. Examples 1-8 use metal salts precipitated with sodium hydroxide, while Examples 9-15 use metal salts precipitated with carbonates. The difference lies in the fact that carbonates can have more pores when forming the coating layer, while hydroxides provide a denser coating.

[0146] Comparative Example 1:

[0147] Li2CO3, (Co) 0.97 Al 0.03 Li3O4 and La2O3 were weighed and mixed uniformly according to a molar ratio of Li:Co:La of 1.05:1:0.0005. The mixture was placed in a muffle furnace under air atmosphere and sintered at 1050℃ for 12 hours. After natural cooling, the mixture was crushed, ground, and sieved to obtain doped lithium cobalt oxide (Li3O4). 1.02 Co 0.97 Al 0.03 La 0.0005 O2.

[0148] Comparative Example 2:

[0149] Li2CO3, (Co) 0.97 Al 0.03 Li3O4 and La2O3 were weighed and mixed uniformly according to a molar ratio of Li:Co:La of 1.05:1:0.0005. The mixture was placed in a muffle furnace under air atmosphere and sintered at 1050℃ for 12 hours. After natural cooling, the mixture was crushed, ground, and sieved to obtain doped lithium cobalt oxide (Li3O4). 1.02 Co 0.97 Al 0.03 La 0.0005 O2

[0150] Subsequently, doped lithium cobalt oxide, alumina, tungsten oxide, yttrium oxide, and titanium oxide were mixed using a high-performance mixer at a speed of 2000 r / min. 1000 g of the mixture contained 10 g of alumina, 5 g of titanium oxide, 5 g of tungsten oxide, and 5 g of yttrium oxide. The mixture was then sintered at 800 °C for 8 hours in an air atmosphere. After natural cooling, the cathode material was obtained by crushing, grinding, and sieving. The cathode material was then used to prepare a battery and subjected to relevant tests.

[0151] Comparative Example 3:

[0152] Li2CO3, (Co) 0.97 Al 0.03Li3O4 and La2O3 were weighed and mixed uniformly according to a molar ratio of Li:Co:La of 1.05:1:0.0005. The mixture was placed in a muffle furnace under air atmosphere and sintered at 1050℃ for 12 hours. After natural cooling, the mixture was crushed, ground, and sieved to obtain doped lithium cobalt oxide (Li3O4). 1.02 Co 0.97 Al 0.03 La 0.0005 O2

[0153] Subsequently, doped lithium cobalt oxide, cobalt hydroxide, aluminum oxide, tungsten oxide, yttrium oxide, and titanium oxide were mixed using a high-performance mixer at a speed of 2000 r / min. 1000g of the mixture contained 20g of cobalt hydroxide, 10g of aluminum oxide, 5g of titanium oxide, 5g of tungsten oxide, and 5g of yttrium oxide. The mixture was then sintered at 800℃ for 8 hours in an air atmosphere. After natural cooling, the mixture was crushed, ground, and sieved to obtain the cathode material. This cathode material was then used to prepare a battery and subjected to relevant tests.

[0154] Comparative Example 4:

[0155] Li2CO3, (Co) 0.97 Al 0.03 Li3O4 and La2O3 were weighed and mixed uniformly according to a molar ratio of Li:Co:La of 1.05:1:0.0005. The mixture was placed in a muffle furnace under air atmosphere and sintered at 1050℃ for 12 hours. After natural cooling, the mixture was crushed, ground, and sieved to obtain doped lithium cobalt oxide (Li3O4). 1.02 Co 0.97 Al 0.03 La 0.0005 O2

[0156] Subsequently, doped lithium cobalt oxide, alumina, magnesium oxide, and titanium oxide were mixed using a super mixer at a speed of 2000 r / min. 1000g of the mixture contained 5g of alumina, 3g of titanium oxide, and 3g of magnesium oxide. The mixture was then sintered at 800℃ for 8 hours in an air atmosphere. After natural cooling, the cathode material was obtained by crushing, grinding, and sieving. The cathode material was then used to prepare a battery and subjected to relevant tests.

[0157] The cathode materials of the examples and comparative examples were prepared into cathode sheets and assembled into lithium-ion batteries. Their 0.1C capacity at 4.6V (Vs Li) and 1C cycle performance at the same voltage were tested.

[0158] Preparation of the positive electrode sheet: The positive electrode material, conductive agent acetylene black, and binder PVDF (polyvinylidene fluoride) were thoroughly mixed in an N-methylpyrrolidone solvent system at a mass ratio of 97:1.5:1.5. The mixture was then coated onto aluminum foil, dried, and cold-pressed to form the corresponding positive electrode sheets. The positive electrode sheets, separator, and negative electrode sheets were assembled into the corresponding lithium-ion batteries. The resulting batteries were subjected to the following tests.

[0159] The positive electrode material exhibits the following characteristics under a voltage system of 3.0–4.6V and a high temperature of 45°C: capacity under 0.1C charge / discharge and cycle retention rate under 1C current rate for 50 cycles.

[0160] Table 1. Composition and performance test results of the cathode materials in the examples and comparative examples.

[0161]

[0162]

[0163] A comparison of the data from the examples and comparative examples shows that the more coating material there is, the more slight the impact on the capacity of the cathode material. The reduction in active material results in a slight decrease in capacity. However, compared to the uncoated comparative example, the examples all show a significant improvement in cycle life.

[0164] The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiments. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A positive electrode material, characterized in that, The positive electrode material includes component 1, component 2, component 3 and component 4; Component 1 is a chemical formula Li x M 1-y Me y O2 is a substance in which M=Co 1-a-b Al a Z b Me is one or more of Ni, Ti, Y, W, La, Zr, and Nb, and Z is one or more of Mg, W, Nb, and Ti; 0.97≤x≤1.06, 0≤y≤0.1, 0.03≤a≤0.05, and 0.0005≤b≤0.01; Component 2 is a chemical formula Li j Ni k Co l A m D n The substance of O2, wherein 0≤j≤1, 0≤k≤0.5, 0≤l≤1.5, 0≤m≤0.01, 0≤n≤0.01, and k and l are not simultaneously 0, A is one or more of Al, Mg, W, Nb, and Mo, and D is one or more of Na, Ti, Li, Al, Mg, Zr, Y, La, Mo, Ce, and Nb; Component 3 is a chemical formula Li j’ Ni k Co l A m D n O2 is a substance in which k, l, m, n, A, and D are defined as described above, j' <j; The chemical formula of component 4 is Li x M 1-y Me y O2 substances, where M= Ni 1-a-b Al a Z b The definitions of Me, Z, x, y, a, and b are as described above; Component 2 is a coating layer with a thickness of 10nm-100nm; component 3 is coated on the surface of component 2; component 4 is located between component 2 and component 1; The Dv50 of the positive electrode material is 15μm-20μm; The mass of component 1 accounts for 96wt% to 99.5wt% of the total mass of the cathode material, the mass of component 2 accounts for 0.5wt% to 4wt% of the total mass of the cathode material, the mass of component 3 accounts for 0 to 1wt% of the total mass of the cathode material, and the mass of component 4 accounts for 0 to 1wt% of the total mass of the cathode material.

2. The cathode material according to claim 1, characterized in that, The raw materials for preparing components 2, 3, and 4 include Ni 1+d Co 2-d A e (OH) g (CO3) h The substance and / or chemical formula is Ni 1+d Co 2-d A e The substance of O4; wherein, 0≤d≤0.2, 0≤e≤0.01, 0≤g≤4, 0≤h≤2, and g and h are not both 0; A is one or more of Al, Mg, W, Nb, and Mo.

3. The cathode material according to claim 2, characterized in that, The raw materials for preparing components 2, 3, and 4 also include those with the chemical formula D. f O i The substance is a mixture of Na, Ti, Li, Al, Mg, Zr, Y, La, Mo, Ce, and Nb, where D is one or more of Na, Ti, Li, Al, Mg, Zr, Y, La, Mo, Ce, and Nb, and f and i satisfy the chemical valence equilibrium of element D.

4. A positive electrode sheet, said positive electrode sheet comprising the positive electrode material according to any one of claims 1-3.

5. A battery comprising the positive electrode material according to any one of claims 1-3, or the battery comprising the positive electrode sheet according to claim 4.

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