Multi-element positive electrode material and manufacturing method thereof, lithium ion battery

Abstract

This application relates to the technical field of lithium-ion batteries, and discloses a multi-component cathode material, a method for manufacturing the same, and a lithium-ion battery. The surface of the multi-component cathode material includes dot-shaped coating and / or island-shaped coating, and the particle cumulative distribution of the multi-component cathode material is 1% particle size D 1 ≧0.7 μm, and the arithmetic mean roughness Ra of the coating measured by a three-dimensional scanning electron microscope of the multi-component cathode material satisfies 20 nm ≦ Ra ≦ 200 nm. The coverage rate Q of the dot-shaped coating and / or island-shaped coating of the multi-component cathode material satisfies 3% ≦ Q ≦ 30%. The surface of the multi-component cathode material includes dot-shaped coating and / or island-shaped coating, and the coating has a specific arithmetic mean roughness and coverage rate. In addition, the multi-component cathode material has a large particle size distribution D 1 to reduce the fine powder content in the multi-component cathode material and enable the lithium-ion battery including the cathode material to have excellent capacity and cycle performance.

Description

[Technical Field]

[0001] The present application relates to the technical field of lithium ion batteries, and in particular to a multi-component positive electrode material and its manufacturing method, and a lithium ion battery. [Background technology]

[0002] In recent years, lithium-ion batteries have been widely used in portable electronic devices, electric vehicles, energy storage systems, and the like due to their high energy density. Although lithium-ion batteries are widely used, electric vehicles currently do not meet the needs of the majority of consumers compared to fuel-powered vehicles, mainly due to issues such as short driving range, poor performance in low temperatures, and safety. The cathode material is the main limitation on the performance of lithium-ion batteries. While the energy density of graphite anodes can reach 360mAh / g, the energy density of cathode materials is only 180mAh / g for ternary 622 materials. Furthermore, the cathode material is the most expensive and heaviest major component of lithium-ion batteries. Therefore, improving the energy density and cycling stability of cathode materials can effectively reduce the weight and price of electric vehicles. Summary of the Invention [Problem to be solved by the invention]

[0003] The purpose of this application is to overcome the problem that the capacity and cycle performance of existing positive electrode materials for lithium ion batteries in the prior art cannot meet actual needs, and to provide a multi-component positive electrode material, a manufacturing method thereof, and a lithium ion battery, wherein the surface of the multi-component positive electrode material comprises a dot-shaped coating and / or an island-shaped coating, and the coating has a specific arithmetic mean roughness and coverage rate. The multi-component positive electrode material also has a large particle size distribution D1, thereby reducing the fine powder content in the multi-component positive electrode material and ensuring that lithium ion batteries containing the positive electrode material have excellent capacity and cycle performance. [Means for solving the problem]

[0004] In order to achieve the above object, in a first aspect of the present application, there is provided a multi-component positive electrode material, the multi-component positive electrode material having a surface including a dot-shaped coating and / or an island-shaped coating, The particle cumulative distribution of the multi-component positive electrode material is 1% particle size D1≧0.7 μm; the arithmetic mean roughness Ra of the coating of the multi-component positive electrode material measured by a three-dimensional scanning electron microscope satisfies 20 nm≦Ra≦200 nm; The coverage Q of the dot-shaped coating and / or island-shaped coating of the multi-component positive electrode material satisfies 3%≦Q≦30%.

[0005] In a second aspect of the present application, there is provided a method for producing a multi-element positive electrode material, said method comprising: (1) mixing a multi-component cathode material precursor, a first lithium source, and an optional dopant, and sintering at a first elevated temperature to obtain a multi-component cathode material process product 1; (2) The multi-component positive electrode material process product 1 is coarsely crushed, and then washed with an acid solution, washed with water, and dried to obtain a multi-component positive electrode material process product 2; (3) Mixing the multi-component positive electrode material process 2, an optional second lithium source and a coating agent, and then sieving the mixed material through a second high-temperature sintering process to obtain the multi-component positive electrode material; The conditions for the acid solution washing are that the concentration of the acid solution is 0.01 to 0.05 g / mL, the washing time is 1 to 120 s, and the sintering temperature T2 of the second high-temperature sintering is 200 to 1000 ° C. The amount of the coating agent added is added according to the stoichiometric ratio 0<[n(J)] / [n(Ni)+n(Co)+n(Mn)]≦0.03.

[0006] In a third aspect of the present application, there is provided a multi-element positive electrode material produced by the above method.

[0007] In a fourth aspect of the present application, there is provided a lithium ion battery, the lithium ion battery comprising the multi-component positive electrode material.

[0008] According to the above technical solutions, the multi-element positive electrode material and its manufacturing method, and the lithium ion battery provided by the present application can achieve the following beneficial effects: The surface of the multi-component positive electrode material provided by the present application includes a dot-like coating and / or island-like coating, and the coating has a specific arithmetic mean roughness and coverage. The multi-component positive electrode material also has a large particle size distribution D1, which reduces the fine powder content in the multi-component positive electrode material and ensures that lithium-ion batteries including the positive electrode material have excellent capacity and cycle performance.

[0009] In the manufacturing method of the multi-component positive electrode material provided by this application, an acid solution washing method is adopted to realize dissociation of the multi-component positive electrode material process product 1 obtained by first high-temperature sintering, achieving an excellent dissociation effect without producing fine powder, avoiding the large amount of fine powder produced by the traditional strong dissociation method, and further avoiding the deterioration of paste dispersibility, uneven application, and electrolyte consumption resulting in the deterioration of the cycle performance and storage performance of lithium-ion batteries due to the presence of excessive fine powder. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 2 is an SEM image of the multi-component positive electrode material process product 2 manufactured according to Example 1 of the present application. [Figure 2] 1 is a SEM image of the multi-element positive electrode material prepared according to Example 1 of the present application, and the rectangular annotation is a 1 μm 2 area selected for coating rate calculation. [Figure 3] FIG. 2 is an SEM image of a multi-component positive electrode material process product 2 manufactured according to Comparative Example 1 of the present application. [Figure 4] FIG. 2 is an SEM image of a multi-element positive electrode material prepared according to Comparative Example 1 of the present application. [Figure 5] 1 shows the cycle performance of the positive electrode materials prepared in Example 1 and Comparative Example 1 of the present application under 1C magnification, in which the test temperature is 45° C. and the voltage range is 3 to 4.3V. DETAILED DESCRIPTION OF THE INVENTION

[0011] The endpoints of ranges and any numerical values disclosed herein are not intended to be limited to the precise ranges or values, but rather should be understood to include values close to those ranges or values. Numerical ranges between the individual range endpoints, between the individual range endpoints and single point values, and between the single point values can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges are considered to be specifically disclosed in this application.

[0012] In a first aspect of the present application, there is provided a multi-component positive electrode material, the multi-component positive electrode material comprising a dot-like coating and / or an island-like coating on a surface thereof; The particle cumulative distribution of the multi-component positive electrode material is 1% particle size D1≧0.7 μm; the arithmetic mean roughness Ra of the coating of the multi-component positive electrode material measured by a three-dimensional scanning electron microscope satisfies 20 nm≦Ra≦200 nm; The coverage Q of the dot-shaped coating and / or island-shaped coating of the multi-component positive electrode material satisfies 3%≦Q≦30%.

[0013] In the prior art, multi-component positive electrode materials are generally hard blocks with strong inter-particle adhesion, and after strong dissociation, fine powder is easily generated, which remains on the surface of the multi-component positive electrode material or is mixed into the multi-component positive electrode material. This reduces the dispersibility of the paste during the battery manufacturing process, leads to uneven application, and increases the consumption of fine electrolyte powder, thereby affecting the cycle performance and storage performance of the lithium-ion battery.

[0014] In this application, the multi-component positive electrode material has a large particle size distribution D1, which means that there are few particles with small particle sizes in the multi-component positive electrode material, and the content of fine powder in the multi-component positive electrode material is low, so that a lithium-ion battery containing the positive electrode material has excellent capacity and cycle performance.

[0015] In addition, the surface coating of a positive electrode material can significantly improve the structural stability of the material. While much research in the prior art has focused on the effect of the coating element type on the material to improve the cycle and storage performance of lithium-ion batteries, the inventors of the present application have discovered through research that the coating amount and coating state of the surface coating of a multi-component positive electrode material also have a very important effect on the multi-component positive electrode material. Specifically, when the dot-shaped coating and / or island-shaped coating contained on the surface of a multi-component positive electrode material have the arithmetic mean roughness and coverage specified in the present application, lithium-ion batteries manufactured using the multi-component positive electrode material have better electrical performance.

[0016] Furthermore, the multi-component positive electrode material in this application has a low fine powder content, which prevents the adsorption of excessive fine powder into the coating, thereby reducing the effective coating and thus the capacity of the lithium-ion battery containing the multi-component positive electrode material. At the same time, the multi-component positive electrode material in this application has a low fine powder content, which allows the lithium-ion battery manufactured using the multi-component positive electrode material to have excellent cycle performance and capacity even when the amount of coating agent used is reduced.

[0017] In this application, the arithmetic mean roughness Ra of the coating of the multi-element positive electrode material is measured using a three-dimensional scanning electron microscope (3D-SEM) according to the method of JIS B 0601 (2001). The coating coverage is defined as the surface roughness of a single particle under the electron microscope within 1 μm 2 The total area of the dot-shaped coating and / or island coating within the area is 1 μm 2 The average value is taken from 300 different particle areas, as shown in the annotated box in Figure 2.

[0018] In one preferred embodiment of the present application, the particle cumulative distribution of the multi-component positive electrode material is such that 1% of particle diameters satisfy 1 μm≦D1≦2 μm; the arithmetic mean roughness Ra of the coating of the multi-component positive electrode material measured by a three-dimensional scanning electron microscope satisfies 30 nm≦Ra≦100 nm; The coverage Q of the dot-shaped coating and / or island-shaped coating of the multi-component positive electrode material satisfies 5%≦Q≦15%.

[0019] According to the present application, the particle cumulative distribution of the multi-component positive electrode material is 50% particle size D 50 is 2-8 μm, preferably 2.5-7 μm.

[0020] In this application, the particle size D1 of the particle cumulative distribution of 1% and the particle size D of the particle cumulative distribution of 50% of the particle 50 is measured by a laser granulometer.

[0021] According to the present application, the average dimension P of the multi-element positive electrode material measured by SEM 50 is 0.8-6 μm, preferably 1-4 μm.

[0022] According to the present application, the specific surface area S of the multi-element positive electrode material is 0.2 m 2 / g≦S≦1.2m 2 / g and / or 1 / P 50 -0.1≦S≦1 / P 50 Meets +0.2.

[0023] In this application, P 50 is in μm and S is in m 2 The relationship is expressed in units of / g and the above relationship is a numerical relationship only.

[0024] In this application, the multi-component positive electrode material has a large particle size distribution D1 and a small specific surface area S, and the specific surface area S is equal to the average size P of the primary particles. 50 The specific surface area S and the average size of the primary particles P 50 There is a clear correlation between the macro index and the micro particle size. In particular, the specific surface area of the multi-element positive electrode material is 0.2m 2 / g≦S≦1.2m 2 / g and 1 / P 50 -0.1≦S≦1 / P 50Satisfying +0.2 indicates that suitable dissociation conditions and suitable coating tempering conditions are adopted during the manufacturing process of the positive electrode material, and that the multi-component positive electrode material provided in this application does not generate fine powder due to excessive dissociation, nor does it have a large amount of adhesion due to insufficient dissociation. If the particle size distribution D1 is too small (i.e., the fine powder content is high), the specific surface area S of the multi-component positive electrode material will be too large, and if insufficient dissociation causes a large amount of adhesion, the specific surface area S of the multi-component positive electrode material will be small, and the specific surface area S and the average primary particle size P 50 No good arithmetic relationship can be established.

[0025] In this application, the surface coating condition also affects the specific surface area of the material. If the surface coating remains excessively, the specific surface area will be large, and if the surface coating does not remain sufficiently, the specific surface area will be small. Only when the surface coating remains within an appropriate range will the above relationship be established and the electrochemical performance of the multi-element positive electrode material will be good.

[0026] Furthermore, the specific surface area S of the multi-element positive electrode material is 0.3 m 2 / g≦S≦1m 2 / g and / or 1 / P 50 -0.05≦S≦1 / P 50 Meets +0.05.

[0027] In one preferred embodiment of the present application, the specific surface area S of the multi-component positive electrode material is 0.2 m 2 / g≦S≦1.2m 2 / g and 1 / P 50 -0.1≦S≦1 / P 50 Meets +0.2, Preferably, 0.3 m 2 / g≦S≦1m 2 / g and 1 / P 50 -0.05≦S≦1 / P 50 Meets +0.05.

[0028] According to the present application, the multi-component positive electrode material is a spherical and / or ellipsoidal particle.

[0029] According to the present application, the base of the multi-element positive electrode material has the structure shown in Formula I, and the coating comprises a J element-containing lithium oxygen compound and / or a J element-containing oxide. Li a Ni x Mn y Co z M b O2 formula I. Among them, 0.9≦a≦1.1, 0.5≦x<1, 0 <y<0.5、0<z<0.5、0≦b≦0.02であり、 The content of the base and the coating in the positive electrode material satisfies 0<[n(J)] / [n(Ni)+n(Co)+n(Mn)]≦0.03; M and J are each independently selected from at least one of Ba, Ra, Zr, Fe, Ca, Zn, B, W, Nb, Cd, Pb, Si, Mo, Cu, V, Ta, Cr, La, Al, Ce, Er, Ho, Y, Mg, Sr, and Ti.

[0030] In the present application, the J element-containing lithium oxygen compound and / or J element-containing oxide may contain at least one element selected from the group consisting of Ni, Co, Mn, and M from the base.

[0031] Furthermore, 1≦a≦1.06, 0.6≦x<1, 0≦y≦0.4, 0≦z≦0.4, and 0.001≦b≦0.01; The content of the base and the coating makes the positive electrode material satisfy 0.001≦[n(J)] / [n(Ni)+n(Co)+n(Mn)]≦0.01; M and J are each independently selected from at least one of Ba, Zr, B, W, Nb, La, Al, Y, Mg, Sr, and Ti.

[0032] In a second aspect of the present application, there is provided a method for producing a multi-element positive electrode material, the method comprising: (1) mixing a multi-component cathode material precursor, a first lithium source, and an optional dopant, and sintering at a first elevated temperature to obtain a multi-component cathode material process product 1; (2) The multi-component positive electrode material process product 1 is coarsely crushed, and then washed with an acid solution, washed with water, and dried to obtain a multi-component positive electrode material process product 2; (3) Mixing the multi-component positive electrode material process 2, an optional second lithium source, and a coating agent, sintering at a second high temperature, and sieving to obtain the multi-component positive electrode material; The conditions for the acid solution washing are that the concentration of the acid solution is 0.01 to 0.05 g / mL and the washing time is 1 to 120 s; The sintering temperature T2 of the second high-temperature sintering is 200 to 1000°C; The amount of the coating agent added is added according to the stoichiometric ratio 0<[n(J)] / [n(Ni)+n(Co)+n(Mn)]≦0.03.

[0033] In the prior art, during the manufacturing process of multi-component positive electrode materials, the primary sintering temperature is high, which tends to form a hard block after sintering, and the particles tend to stick together badly, requiring a strong dissociation method to dissociate them, which tends to produce fine powder.

[0034] In the present application, in the manufacturing method of the multi-component positive electrode material, an acid solution washing method is adopted to realize dissociation of the multi-component positive electrode material process product 1 obtained by first high-temperature sintering, achieving an excellent dissociation effect without producing fine powder, avoiding the large amount of fine powder produced by the conventional strong dissociation method, and further avoiding the deterioration of paste dispersibility, uneven application, and electrolyte consumption resulting in the deterioration of the cycle performance and storage performance of the lithium-ion battery due to the presence of excessive fine powder.

[0035] Furthermore, the acid solution washing corrodes the surface of the multi-component positive electrode material processed product 1, resulting in a higher surface roughness of the resulting multi-component positive electrode material processed product 2. At the same time, the surface of the multi-component positive electrode material processed product 2 is free of attached particles. Therefore, after mixing with a coating agent and performing a second high-temperature sintering, the coating is more tightly bonded to the surface of the resulting multi-component positive electrode material. During the cycling process of the lithium-ion battery, the coating is less likely to detach from the surface of the positive electrode material, resulting in a better coating effect. In particular, by controlling the acid solution washing conditions to meet the above ranges, the particles of the resulting multi-component positive electrode material can be prevented from separating from each other and producing fine powder. Specifically, if the acid solution concentration is too low or the washing time is too short, the separation effect will not be achieved. If the acid solution concentration is too high or the washing time is too long, the surface structure of the multi-component positive electrode material will be damaged, ultimately resulting in a decrease in the performance of lithium-ion batteries incorporating the multi-component positive electrode material.

[0036] Furthermore, in the present application, by washing the processed product 1 of the multi-component positive electrode material with an acid solution, the multi-component positive electrode material has a low fine powder content, and even if the amount of coating agent used is reduced, the lithium ion battery using the multi-component positive electrode material provided in the present application can still have excellent cycle performance and capacity.

[0037] In the present application, the multi-component positive electrode material processed product 2 is a spherical and / or ellipsoidal particle with good independence.

[0038] Furthermore, the acid solution cleaning process removes residual lithium carbonate and lithium hydroxide from the surface of the processed multi-component positive electrode material 1, reducing the residual lithium on the surface of the resulting multi-component positive electrode material and making the surface layer prone to lithium deficiency. Therefore, a second lithium source is added during the second high-temperature sintering process to ensure high capacity for the resulting lithium-ion battery containing the multi-component positive electrode material. Furthermore, the second lithium source has the effect of enhancing solubility, and adding the second lithium source during the second high-temperature sintering process can reduce the second high-temperature sintering temperature and reduce energy consumption.

[0039] According to the present application, the multi-element positive electrode material precursor is a nickel, cobalt, manganese ternary positive electrode material precursor.

[0040] In this application, the multi-element positive electrode material precursor can be commercially purchased or can be prepared by oneself.

[0041] According to the present application, the first lithium source and the second lithium source are each independently selected from the group consisting of lithium carbonate, lithium hydroxide, lithium oxide, and lithium acetate.

[0042] According to the present application, the dopant and the coating agent are each independently selected from carbonates, hydroxides, oxides, and acetates that can provide at least one element selected from Ba, Ra, Zr, Fe, Ca, Zn, B, W, Nb, Cd, Pb, Si, Mo, Cu, V, Ta, Cr, La, Al, Ce, Er, Ho, Y, Mg, Sr, and Ti.

[0043] According to the present application, the acid solution is at least one selected from sulfuric acid, carbonic acid, acetic acid, and oxalic acid.

[0044] According to the present application, the total amount of the first lithium source and the second lithium source is added according to the stoichiometric ratio 0.9≦[n(Li1)+n(Li2)] / [n(Ni)+n(Co)+n(Mn)]≦1.1.

[0045] Furthermore, the total amount of the first lithium source and the second lithium source is added according to the stoichiometric ratio 1≦[n(Li1)+n(Li2)] / [n(Ni)+n(Co)+n(Mn)]≦1.06.

[0046] In the present application, there are no particular limitations on the amounts of the first lithium source and the second lithium source added, and the total amount of the first lithium source and the second lithium source added may be within the above range.

[0047] In one specific embodiment of the present application, the amount of the first lithium source added is added according to a chemical ratio of 0.9≦[n(Li1)] / [n(Ni)+n(Co)+n(Mn)]≦1.05, and the amount of the second lithium source added is added according to a chemical ratio of 0≦[n(Li2)] / [n(Ni)+n(Co)+n(Mn)]≦0.05.

[0048] In one preferred embodiment of the present application, the addition amount of the first lithium source is added according to the stoichiometric ratio 0.99≦[n(Li1)] / [n(Ni)+n(Co)+n(Mn)]≦1.05, and the addition amount of the second lithium source is added according to the stoichiometric ratio 0.01≦[n(Li2)] / [n(Ni)+n(Co)+n(Mn)]≦0.01.

[0049] According to the present application, the amount of dopant added is added according to the stoichiometric ratio 0≦[n(M)] / [n(Ni)+n(Co)+n(Mn)]≦0.02, preferably according to the stoichiometric ratio 0≦[n(M)] / [n(Ni)+n(Co)+n(Mn)]≦0.01.

[0050] According to the present application, the amount of said coating agent added is added according to the stoichiometric ratio 0<[n(J)] / [n(Ni)+n(Co)+n(Mn)]≦0.03.

[0051] In this application, when the amount of coating agent added is controlled to meet the above range, the resulting multi-component positive electrode material has an appropriate coating content, thereby ensuring that the resulting multi-component positive electrode material has a stable structure and does not leave excessive coating on the surface. Specifically, when the amount of coating agent added is too high, too much coating remains on the surface of the material, which affects the transmission of lithium ions and reduces the capacity and power performance of lithium ion batteries containing the multi-component positive electrode material. When the amount of coating agent added is too low, the coating will not play its role, and during cycling, the electrolyte is likely to damage the surface structure of the multi-component positive electrode material, which will reduce the performance of lithium ion batteries containing this multi-component positive electrode material.

[0052] According to the present application, the amount of said coating agent added is added according to the stoichiometric ratio 0.001≦[n(J)] / [n(Ni)+n(Co)+n(Mn)]≦0.01.

[0053] According to the present application, the conditions of the first high-temperature sintering include: a sintering temperature T1 of 700 to 1200°C, a sintering time of 10 to 30 hours, and a sintering atmosphere of oxygen and / or air.

[0054] Furthermore, the conditions for the first high-temperature sintering include a sintering temperature T1 of 700 to 1050° C., a sintering time of 15 to 25 hours, and a sintering atmosphere of oxygen and / or air.

[0055] According to the present application, the conditions for the acid solution washing include that the concentration of the acid solution is 0.02 to 0.04 g / mL and the washing time is 5 to 60 seconds.

[0056] In the present application, the coarse grinding may be carried out by a conventional method well known to those skilled in the art, which aims to break down large blocks into smaller blocks, has a weak disintegration strength, and produces a small amount of fine powder, for example, a wide-gap double roll disintegration.

[0057] In this application, the purpose of washing the product with water after washing with the acid solution is to remove any remaining acid solution.

[0058] According to the present application, the sintering temperature of the second high-temperature sintering is 300-900°C.

[0059] According to the present application, the sintering time of the second high-temperature sintering is 5 to 20 hours, preferably 6 to 15 hours.

[0060] According to the present application, said second high temperature sintering is carried out in air and / or oxygen.

[0061] According to the present application, the sintering temperature T2 of the second high-temperature sintering is 200 to 1000°C, and the sintering temperature T2 and the melting point T m satisfies the following relationship: 100×lnT m -200≦T2≦100×lnT m +100.

[0062] In this application, the applicant has found through research that the coating effect of the coating agent on the positive electrode material can be better achieved by adjusting the sintering temperature of the second high-temperature sintering according to the type of coating agent, and specifically, a better coating effect can be obtained by controlling the melting point of the coating agent and the sintering temperature of the second high-temperature sintering to satisfy the above-mentioned relationship.

[0063] Furthermore, the sintering temperature T2 of the second high-temperature sintering is 300 to 900°C, and the sintering temperature T2 and the melting point T of the coating agent are m satisfies the following relationship: 100×lnT m -100 ≤ T2 ≤ 100 × lnT m +50.

[0064] In a third aspect of the present application, there is provided a multi-element positive electrode material produced by the above-described production method.

[0065] In a fourth aspect of the present application, there is provided a lithium ion battery, the lithium ion battery comprising the multi-component positive electrode material.

[0066] The present application will now be described in detail with reference to the following examples. In the following examples, all raw materials are commercially available unless otherwise specified.

[0067] Unless otherwise specified, room temperature in this application refers to 25±2°C.

[0068] In the following examples and comparative examples, relevant parameters are measured by the following methods. (1) Particle size measurement: Laser particle sizer. (2) Morphology and surface roughness measurement: ERA-9200 scanning electron microscope, ELIONIX, Japan. (3) Specific surface area measurement: Micromeritics Tristar 3020 specific surface area meter. (4) Electrochemical performance measurement: In the following examples and comparative examples, the electrochemical performance of the multi-element positive electrode materials is measured using a 2025-type coin cell.

[0069] The manufacturing process of the 2025 coin cell is specifically as follows: Electrode piece preparation: The multi-component positive electrode material, acetylene black, and polyvinylidene fluoride (PVDF) were thoroughly mixed with an appropriate amount of N-methylpyrrolidone (NMP) in a mass ratio of 95:3:2 to form a homogeneous paste. The paste was applied to aluminum foil and dried at 120°C for 12 hours. Then, the foil was punched under a pressure of 100 MPa to prepare a 12 mm diameter, 120 μm thick cathode piece. The loading of the multi-component positive electrode material was 15 mg / cm. 2 is.

[0070] Battery assembly: In a gas glove box filled with argon gas with a moisture and oxygen content of less than 5 ppm, the positive electrode piece, diaphragm, negative electrode piece, and electrolyte were assembled into a 2025-type coin cell and allowed to stand for 6 hours. The negative electrode piece was a 17 mm diameter, 1 mm thick piece of metallic lithium, the diaphragm was a 25 μm thick porous polyethylene membrane (Celgard 2325), and the electrolyte was a mixture of equal parts ethylene carbonate (EC) and diethylene carbonate (DEC) containing 1 mol / L LiPF6.

[0071] Electrochemical performance measurements: In the following examples and comparative examples, the electrochemical performance of the 2025-type coin cell was measured using a Shenzhen Newwell battery test system, and the 0.1C charge / discharge current density was 200mA / g.

[0072] The charge / discharge voltage range is controlled to 3.0 to 4.3 V, and the coin cell is subjected to charge / discharge measurements at 0.1 C at room temperature to evaluate the initial charge / discharge specific capacity and initial charge / discharge efficiency of the multi-element positive electrode material.

[0073] Cycle performance measurement: The charge / discharge voltage range is controlled to 3.0 to 4.3 V, and the coin cell is subjected to two charge / discharge cycles at 0.1 C and 80 charge / discharge cycles at 1 C at a constant temperature of 45°C to evaluate the high-temperature capacity retention of the multi-element positive electrode material.

[0074] Measurement of multiplier performance: The charge / discharge voltage range was controlled between 3.0 and 4.3 V. The coin cell was charged / discharged twice at 0.1 C and once at 0.2 C, 0.33 C, 0.5 C, and 1 C at room temperature. The multiplier performance of the multi-component cathode material was evaluated based on the ratio of the 0.1 C initial discharge specific capacity to the 1 C discharge specific capacity. The 0.1 C initial discharge specific capacity was the discharge specific capacity of the first cycle of the coin cell, and the 1 C discharge specific capacity was the discharge specific capacity of the sixth cycle of the coin cell.

[0075] Example 1 This example illustrates a cathode material prepared using the method of the present application. (1) Nickel, cobalt, manganese hydroxide precursor Ni 0.8 Co 0.1 Mn 0.1 (OH)2, lithium hydroxide, and aluminum oxide are uniformly mixed in the ratio of n(Li):n(Al):[n(Ni)+n(Co)+n(Mn)]=1.04:0.001:1, sintered in an oxygen atmosphere at 890°C for 20 hours, and then cooled naturally to room temperature to obtain multi-component cathode material process product 1. (2) The multi-component cathode material process product 1 is coarsely crushed and washed with 0.03 g / mL sulfuric acid for 30 seconds, then washed with deionized water to remove residual sulfuric acid, and dried to obtain the multi-component cathode material process product 2, Li 1.04 Ni 0.8 Co 0.1 Mn 0.1 Al 0.001 Get O2. (3) Multi-component positive electrode material process product 2: Lithium hydroxide, magnesium oxide, and tungsten oxide are uniformly mixed in the ratio of n(Li):n(Mg):n(W):[n(Ni)+n(Co)+n(Mn)]=0.01:0.005:0.002:1, sintered at 700°C for 12 hours in an oxygen atmosphere, cooled naturally to room temperature, and sieved to obtain the multi-component positive electrode material.

[0076] Examples 2 to 7 The composition and technical parameters were different from those of Example 1, and the specific details are shown in Tables 1-1 and 1-2. Otherwise, the multi-element positive electrode material was prepared in the same manner as in Example 1. [Table 1-1] [Table 1-2]

[0077] Comparative Example 1 (1) Nickel, cobalt, manganese hydroxide precursor Ni 0.8 Co 0.1 Mn 0.1 (OH)2, lithium hydroxide, and aluminum oxide are uniformly mixed in the ratio of n(Li):n(Al):[n(Ni)+n(Co)+n(Mn)]=1.04:0.001:1, sintered in an oxygen atmosphere at 890°C for 20 hours, and then cooled naturally to room temperature to obtain multi-component cathode material process product 1. (2) Multi-component positive electrode material process product 1 is coarsely crushed and disintegrated using a narrow-gap double roll to a target particle size of 6.2 μm, to produce multi-component positive electrode material process product 2, Li 1.04 Ni 0.8 Co 0.1 Mn 0.1 Al 0.001 Get O2. (3) Multi-component positive electrode material process product 2: Lithium hydroxide, magnesium oxide, and tungsten oxide are uniformly mixed in the ratio of n(Li):n(Mg):n(W):[n(Ni)+n(Co)+n(Mn)]=0.01:0.005:0.002:1, sintered at 700°C for 12 hours in an oxygen atmosphere, cooled naturally to room temperature, and sieved to obtain the multi-component positive electrode material.

[0078] Comparative Example 2 The method of Example 1 is the same as that of Example 1 except that in step (3), the multi-component positive electrode material process product 2, lithium hydroxide is mixed uniformly according to the ratio of n(Li):[n(Ni)+n(Co)+n(Mn)]=0.01:1. Otherwise, the multi-component positive electrode material Li 1.05 Ni 0.8 Co 0.1 Mn 0.1 Al 0.001 O2 is obtained. The characteristic parameter measurement data are shown in Tables 2-1 and 2-2.

[0079] Comparative Example 3 The method of Example 1 was followed, except that in step (3), ternary material process product 2, lithium hydroxide, magnesium oxide, and tungsten oxide, were uniformly mixed in a ratio of n(Li):n(Mg):n(W):[n(Ni)+n(Co)+n(Mn)]=0.01:0.03:0.03:1 and sintered in an oxygen atmosphere at 400°C for 12 hours. A multi-component positive electrode material was obtained in the same manner as in Example 1. The characteristic parameter measurement data are shown in Tables 2-1 and 2-2.

[0080] Comparative Example 4 The method of Example 1 was followed, except that in step (3), sintering was performed in an oxygen atmosphere at 1100°C, and other steps were the same as in Example 1 to obtain a multi-element positive electrode material. The characteristic parameter measurement data are shown in Tables 2-1 and 2-2.

[0081] Comparative Example 5 The multi-element positive electrode material was obtained in the same manner as in Example 1, except that in step (2), 0.1 g / mL sulfuric acid was used for washing for 180 s. The characteristic parameter measurement data are shown in Tables 2-1 and 2-2.

[0082] Measurement example (1) Morphology measurement The present application measured the scanning electron microscope images of the positive electrode materials prepared in the above examples and comparative examples, and measured the average primary particle size P 50The arithmetic mean roughness Ra and coverage Q were statistically calculated and are shown in Figures 1-4 and Tables 2-1 and 2-2. Figure 1 shows that the surface of the multi-component positive electrode material processed product 2 obtained in Example 1 is free of adhesion and has good particle independence, while Figure 2 shows the surface of the multi-component positive electrode material with a dot-like and island-like coating. The surface of the multi-component positive electrode material processed product 2 obtained in Comparative Example 1 has a lot of fine powder, a lot of debris, and worn corners, and in addition to the coating, there is a lot of fine powder on the surface of the multi-component positive electrode material. (2) Physical property measurement The present application relates to the multi-component positive electrode materials D1, D2, D3, D4, D5, D6, D7, D8, D9, D10, D11, D12, D13, D14, D15, D16, D17, D18, D19, D20, D21, D22, D23, D24, D25, D26, D27, D28, D29, D30, D3 50 , P 50 , S, Ra, and Q were measured, and the specific details are shown in Tables 2-1 and 2-2. [Table 2-1] [Table 2-2]

[0083] From Tables 2-1 and 2-2, it can be seen that compared to Example 1, Example 2 had a low sulfuric acid concentration and a short washing time, resulting in a small S, insufficient dissociation, and particles sticking together. In Example 3, the sulfuric acid concentration was high and the washing time was long, resulting in a large S, and D 50 and P 50 becomes smaller, indicating that the surface of the positive electrode material is partially corroded by sulfuric acid.

[0084] Compared to Example 1, Example 4 has a larger coating amount, so more coating agent remains on the surface, resulting in larger S, Ra, and Q. In Example 5, the second high-temperature sintering temperature is higher, so more coating agent is mixed into the outer layer of the positive electrode material, leaving less residue on the surface, resulting in smaller S, Ra, and Q.

[0085] Examples 6 and 7 show that different compositions and coating agents can also be applied.

[0086] Compared to Example 1, Comparative Example 1 was disaggregated using a double roll to the target particle size, and produced a large amount of fine powder by disaggregation, with a small D1, a large S, a rough surface, and a large Ra. This is consistent with the results in Figures 3 and 4.

[0087] In Comparative Example 2, no coating was performed, and the particles slightly stuck together after sintering at the second high temperature, resulting in a small S. In Comparative Example 3, the coating amount was too large and the second high-temperature sintering temperature was low, resulting in a large amount of coating agent remaining on the surface, resulting in a very large S, and large surface roughness Ra and surface coverage Q. In Comparative Example 4, the second high-temperature sintering temperature was too high, resulting in all of the coating agent being mixed into the outer layer of the positive electrode material and the particles sticking together, resulting in a very small S.

[0088] In Comparative Example 5, the acid solution was highly concentrated and the cleaning time was long, so the surface was severely corroded and D 50 and P 50 becomes smaller and S becomes larger. [Table 3]

[0089] From Table 3, compared with Example 1, Example 2 has a small S, particles stick, the material capacity is slightly lower, and the magnification and cycle performance are slightly reduced. Example 3 has a large S, the surface is partially corroded, and the cycle performance of the material is poor.

[0090] Compared with Example 1, Example 4 has a larger coating amount, resulting in more coating material remaining on the surface, which hinders lithium ion transmission, lowers material capacity, reduces magnification, and slightly reduces cycle time. Example 5 has a higher second high-temperature sintering temperature, resulting in less coating material remaining on the surface, which results in poor cycle time. Example 8 does not contain a second lithium source, resulting in lithium deficiency on the surface and low capacity.

[0091] Compared with Example 1, Comparative Example 1 contained more fine powder, consumed more electrolyte, and was deficient in electrolyte, resulting in a decrease in material capacity, and the fine powder made the battery plate unstable, resulting in poor cycle performance.

[0092] In Comparative Example 2, no coating was applied, which led to structural changes on the surface during the battery charge / discharge process, resulting in a decrease in cycle life. In Comparative Example 3, there was a large amount of residue on the surface, which prevented lithium ion transmission and reduced the material's expansion ratio. In Comparative Example 4, the second high-temperature sintering temperature was high, which resulted in little residue of coating agent and particles sticking together, resulting in poor cycle stability.

[0093] In Comparative Example 5, the concentration of the acid solution was too high and the cleaning time was too long, which resulted in severe corrosion of the material and reduced cycle stability.

[0094] Although the above describes the preferred embodiments of the present application in detail, the present application is not limited thereto. Within the technical concept of the present application, the technical solution of the present application can be easily modified in various ways, including combining individual technical features in any other suitable manner. These easy modifications and combinations are also considered to be the disclosure content of the present application and are included in the protection scope of the present application.

Claims

1. A multi-component positive electrode material, wherein a surface of the multi-component positive electrode material comprises a dot-like coating and / or an island-like coating; The particle cumulative distribution of the multi-component positive electrode material is 1% particle size D １ ≧0.7 μm, the arithmetic mean roughness Ra of the coating of the multi-component positive electrode material measured by a three-dimensional scanning electron microscope satisfies 20 nm≦Ra≦200 nm; the coverage Q of the dot-shaped coating and / or island-shaped coating of the multi-component positive electrode material satisfies 3%≦Q≦30%; the base of the multi-element positive electrode material has the structure shown in Formula I, and the coating comprises a J element-containing lithium oxygen compound and / or a J element-containing oxide; Li a Ni x Mny Co z M b O 2 Formula I wherein 0.9≦a≦1.1, 0.5≦x<1, 0<y<0.5, 0<z<0.5, and 0≦b≦0.02; The content of the base and the coating in the positive electrode material satisfies 0<[n(J)] / [n(Ni)+n(Co)+n(Mn)]≦0.03; M and J are each independently at least one selected from Ba, Ra, Zr, Fe, Ca, Zn, B, W, Nb, Cd, Pb, Si, Mo, Cu, V, Ta, Cr, La, Al, Ce, Er, Ho, Y, Mg, Sr, and Ti.

2. The particle cumulative distribution of the multi-component positive electrode material is 1 μm≦D １ ≦2 μm, the arithmetic mean roughness Ra of the coating of the multi-component positive electrode material measured by a three-dimensional scanning electron microscope satisfies 30 nm≦Ra≦100 nm; 2. The multi-component positive electrode material according to claim 1, wherein the coverage Q of the dot-shaped coating and / or island-shaped coating of the multi-component positive electrode material satisfies 5%≦Q≦15%.

3. The particle cumulative distribution of the multi-component positive electrode material has a particle size D ５０ 3. The multi-component positive electrode material according to claim 1, wherein the average particle diameter is 2 to 8 μm.

4. A method for producing the multi-component positive electrode material of claim 1, comprising: mixing the multi-component cathode material precursor, the first lithium source, and the optional dopant, and performing a first high-temperature sintering to obtain a multi-component cathode material process product 1; The multi-component positive electrode material process product 1 is coarsely pulverized, then washed with an acid solution, washed with water, and dried to obtain a multi-component positive electrode material process product 2. Multi-component positive electrode material process 2: mixing an optional second lithium source and a coating agent, and then performing second high-temperature sintering and sieving to obtain the multi-component positive electrode material; The conditions for washing with the acid solution are that the concentration of the acid solution is 0.01 to 0.05 g / mL and the washing time is 1 to 120 s; The sintering temperature T of the second high-temperature sintering ２ is 200 to 1000°C, the base of the multi-element positive electrode material has the structure shown in Formula I, and the coating comprises a J element-containing lithium oxygen compound and / or a J element-containing oxide; Li ａ Ni ｘ Mn ｙ Co ｚ M ｂ O ２ Formula I and wherein the amount of coating agent added is added according to the stoichiometric ratio 0<[n(J)] / [n(Ni)+n(Co)+n(Mn)]≦0.

03.

5. 5. The method of claim 4, wherein the multi-component positive electrode material precursor is a nickel, cobalt, manganese ternary positive electrode material precursor.

6. 6. The method of claim 5, wherein the total amount of the first lithium source and the second lithium source added is added according to a stoichiometric ratio of 0.9≦[n(Li1)+n(Li2)] / [n(Ni)+n(Co)+n(Mn)]≦1.

1.

7. The first high-temperature sintering condition is a sintering temperature T １ 7. The method according to claim 4, wherein the sintering temperature is 700 to 1200° C., the sintering time is 10 to 30 h, and the sintering atmosphere is oxygen and / or air.

8. The sintering temperature T of the second high-temperature sintering ２ is 200 to 1000°C, and the sintering temperature T ２ and the melting point T of the coating agent ｍ satisfies the following relationship, 100 x lnT ｍ -200≦T ２ ≦100×lnT ｍ 7. The method according to claim 4, wherein the value of the saturation voltage is +100.

9. A lithium ion battery, characterized in that the lithium ion battery comprises the multi-component positive electrode material according to claim 1 or 2.

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