Lithium-rich manganese-based material precursor, positive electrode material and application

Abstract

The invention provides a lithium-rich manganese-based material precursor, a positive electrode material and application. The chemical formula of the lithium-rich manganese-based material precursor is Ni < x > Co < y > Mn < z > MuCO3, wherein x is more than 0 and less than 1, y is more than 0 and less than 1, z is more than 0 and less than 1, u is more than 0 and less than 1, and M is at least one of Ti, Cr, Mg, Zr, B, P, W, Si, Cu, Fe and Ta; the mass percentage content of a sodium element in the lithium-rich manganese-based material precursor is 200 to 3000ppm. The lithium-rich manganese-based material precursor provided by the invention is low in sodium content, the water absorption trend of the lithium-rich manganese-based material precursor and a corresponding positive electrode material can be inhibited, and the first coulombic efficiency and the specific discharge capacity of a battery are improved.

Description

Technical Field

[0001] This invention relates to a lithium-rich manganese-based material precursor, and particularly to a lithium-rich manganese-based material precursor, cathode material, and applications, belonging to the field of lithium-ion batteries. Background Technology

[0002] Lithium-ion batteries are widely used in laptops, mobile phones, and digital products due to their high energy density, good safety performance, long cycle life, and environmental friendliness. However, the development of cathode materials has been slower compared to the development of high-capacity anode materials (approximately 800-1000 mAh / g). Therefore, current researchers are focusing their attention on developing high-capacity and long-cycle-life cathode materials to improve the energy density of lithium-ion batteries.

[0003] Lithium-rich manganese cathode materials exhibit superior electrochemical performance compared to lithium cobalt oxide and lithium iron phosphate. Therefore, the development of high-quality lithium-rich manganese precursors and cathode materials has become a hot topic. Among these, carbonate precursors are relatively simple to synthesize and are widely used. However, the alkaline solution used in the preparation of carbonate precursors is typically sodium carbonate, which leads to excessively high sodium content in the precursor. Excessive sodium content in the precursor causes both the precursor and the corresponding cathode material to readily absorb water, exacerbating side reactions in the battery and degrading the initial coulombic efficiency and discharge specific capacity.

[0004] Therefore, those skilled in the art urgently need to develop a lithium-rich manganese carbonate precursor with low sodium content to improve the initial coulombic efficiency and discharge specific capacity of batteries. Summary of the Invention

[0005] This invention provides a lithium-rich manganese-based material precursor with low sodium content. The cathode material synthesized from this precursor has low sodium content, which can avoid water absorption problems in the cathode material, thereby improving the initial coulombic efficiency and discharge specific capacity of the battery.

[0006] This invention provides a cathode material with low sodium content, which is beneficial for improving the initial coulombic efficiency and discharge specific capacity of the battery.

[0007] This invention provides a method for preparing a cathode material that can produce cathode materials with low sodium content. Furthermore, this method is simple, easy to operate, and conducive to the large-scale production of cathode materials.

[0008] The present invention provides a battery that exhibits excellent initial coulombic efficiency and discharge specific capacity.

[0009] This invention provides a lithium-rich manganese-based material precursor, wherein the chemical formula of the lithium-rich manganese-based material precursor is Ni. x Co y Mnz M u CO3; wherein, 0 < x < 1, 0 < y < 1, 0 < z < 1, 0 < u < 1, and M is at least one of Ti, Cr, Mg, Zr, B, P, W, Si, Cu, Fe, and Ta;

[0010] The sodium content in the lithium-rich manganese-based material precursor is 200-3000 ppm by mass.

[0011] The lithium-rich manganese-based material precursor as described above, wherein the sphericity of the lithium-rich manganese-based material precursor particles is 60-95%.

[0012] And / or, the specific surface area of ​​the lithium-rich manganese-based material precursor is 20-40 m². 2 / g.

[0013] The lithium-rich manganese-based material precursor as described above, wherein the lithium-rich manganese-based material precursor comprises primary particles and / or secondary particles formed from primary particles;

[0014] The primary particles have a particle size of 50-200 nm; the secondary particles have a Dv10 of 1-2 μm, a Dv50 of 6-15 μm, a Dv90 of 15-25 μm, and a (Dv90-Dv10) / Dv50 ratio of 0.6-1.5.

[0015] The lithium-rich manganese-based material precursor described above belongs to the R-3c space group.

[0016] Preferably, the X-ray diffraction pattern of the lithium-rich manganese-based material precursor includes a diffraction peak (104) at 2θ of 30-32° and a diffraction peak at 2θ of 23-25°. Full width at half maximum (FWHM) of diffraction peak (104) (104) The diffraction peaks are at 0.1-0.5°. The ratio of the peak intensity of the diffraction peak (104) to the peak intensity of the diffraction peak. It ranges from 0.1 to 0.7.

[0017] This invention provides a cathode material, wherein the cathode material is prepared by a method comprising the following steps:

[0018] In an inert atmosphere, the lithium-rich manganese-based material precursor described above is calcined to obtain a first intermediate; in an air atmosphere, the first intermediate is mixed with a lithium source and calcined to obtain the cathode material.

[0019] The cathode material described above, wherein the chemical formula of the cathode material is Li[Li a Ni b Coc Mn d M e O2, where 0.1≤a≤0.3, 0<b<1, 0<c<1, 0<d<1, 0<e<1, and M is at least one of Ti, Cr, Mg, Zr, B, P, W, Si, Cu, Fe, and Ta;

[0020] The sodium content in the cathode material is 200-2000 ppm by mass.

[0021] The positive electrode material described above contains a water content of 50-300 ppm by mass.

[0022] And / or, the powder compaction density of the positive electrode material under 5 tons of pressure is 2.5-3.5 g / cc;

[0023] And / or, the specific surface area of ​​the positive electrode material is 1-4 m². 2 / g;

[0024] And / or, the positive electrode material has a Dv10 of 1-5 μm, a Dv50 of 4-12 μm, a Dv90 of 12-20 μm, and a (Dv90-Dv10) / Dv50 ratio of 0.5-1.5.

[0025] The positive electrode material as described above, wherein the sphericity of the positive electrode material is 60-95%;

[0026] Y=97%-X / 1000*(5~10%),

[0027] Wherein, Y is the sphericity of the cathode material, %; and X is the mass percentage of sodium in the cathode material, ppm.

[0028] The cathode material described above belongs to the C2 / m space group;

[0029] Preferably, the X-ray diffraction pattern of the cathode material includes a diffraction peak (003) at 2θ of 18-19°, a diffraction peak (104) at 2θ of 44.2-44.8°, a diffraction peak (006) at 2θ of 38.43°, and a diffraction peak (102) at 2θ of 38.53°; the full width at half maximum (FWHM) of the diffraction peak (003) is... (003) It is 0.01-0.1°;

[0030] The ratio of the peak intensities of diffraction peak (003) and diffraction peak (104), I(003) / I(104), is 1.5-1.8;

[0031] The splitting angles of the diffraction peaks (006) and (102) are 0.3-0.6°.

[0032] The present invention provides a battery comprising the positive electrode material as described above.

[0033] The lithium-rich manganese-based material precursor provided by this invention has a specific chemical composition and low sodium content, which can suppress the water absorption tendency of the lithium-rich manganese-based material precursor. The water absorption of the corresponding cathode material can also be suppressed, thereby avoiding side reactions between water and electrolyte, and thus improving the first coulombic efficiency and discharge specific capacity of the battery.

[0034] The cathode material provided by this invention is prepared based on the above-mentioned lithium-rich manganese-based precursor. The corresponding cathode material has a low sodium content, which can suppress the water absorption tendency of the cathode material and avoid side reactions between water and electrolyte, thereby improving the initial coulombic efficiency and discharge specific capacity of the battery.

[0035] The battery provided by this invention is prepared based on the above-mentioned cathode material, and the battery exhibits excellent initial coulombic efficiency and discharge specific capacity. Attached Figure Description

[0036] Figure 1 The discharge capacity graphs of the batteries in Examples 1-3 and Comparative Example 1 after 50 cycles are shown.

[0037] Figure 2 The image shows the XRD pattern of the lithium-rich manganese-based material precursor of Example 1.

[0038] Figure 3 The image shows the XRD pattern of the cathode material in Example 1.

[0039] Figure 4 Here is a SEM image of the lithium-rich manganese-based material precursor of Example 1;

[0040] Figure 5 This is a SEM image of the lithium-rich manganese-based material precursor of Example 1. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0042] This invention provides a lithium-rich manganese-based material precursor, the chemical formula of which is Ni. x Co y Mn z M uCO3; wherein 0 < x < 1, 0 < y < 1, 0 < z < 1, 0 < u < 1, and M is at least one of Ti, Cr, Mg, Zr, B, P, W, Si, Cu, Fe, and Ta; the mass percentage of sodium in the lithium-rich manganese-based material precursor is 200-3000 ppm, for example, 200 ppm, 300 ppm, 400 ppm, 500 ppm, 600 ppm, 700 ppm, 800 ppm, 900 ppm, 1000 ppm, 1200 ppm, 1500 ppm, 1700 ppm, 2000 ppm, 2300 ppm, 2500 ppm, 2700 ppm, or 3000 ppm, etc.

[0043] This invention does not limit the specific molar ratio of Ni, Co, Mn, and M in the chemical formula of lithium-rich manganese-based material precursors, as long as it satisfies 0 < x < 1, 0 < y < 1, 0 < z < 1, 0 < u < 1 and the chemical valence state.

[0044] The lithium-rich manganese-based precursor provided by this invention has a specific chemical formula and a low sodium content. Using it to prepare cathode materials and applying these materials to batteries results in excellent initial coulombic efficiency and discharge specific capacity. The inventors analyzed the principle behind this and believe the reason lies in the fact that when the sodium content of the lithium-rich manganese-based precursor is within the aforementioned range, it suppresses the water absorption tendency of the precursor, and correspondingly, the water absorption of the cathode material is also suppressed. This avoids side reactions between water and the electrolyte, thereby improving the initial coulombic efficiency and discharge specific capacity of the battery. Furthermore, using a low-sodium lithium-rich manganese-based precursor to prepare the cathode material avoids the excessively cumbersome subsequent washing process that would generate large amounts of wastewater, thus saving costs and being environmentally friendly.

[0045] This invention does not limit the method for achieving the mass percentage content of sodium in lithium-rich manganese-based material precursors. For example, by controlling different preparation processes, the selection and addition amount of each raw material during the preparation process, and the reaction conditions during the preparation process, the mass percentage content of sodium in lithium-rich manganese-based material precursors can be within the above-mentioned range.

[0046] Specifically, the mass percentage of sodium in the lithium-rich manganese-based material precursor of the present invention can be obtained by ICP testing.

[0047] In one specific embodiment, the sphericity of the lithium-rich manganese-based material precursor particles is 60-95%, for example, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or 95%. The low sodium content in the preparation process of the lithium-rich manganese-based material precursor of this invention makes it less likely to generate additional impurity components, which is beneficial for homogeneous nucleation of the lithium-rich manganese-based material precursor, thus ensuring the sphericity of the lithium-rich manganese-based material precursor particles is within the aforementioned range. When the sphericity of the lithium-rich manganese-based material precursor is within the aforementioned range, using the lithium-rich manganese-based material precursor as a raw material to prepare a cathode material for use in a battery results in a uniform lithium-ion transport path within the cathode material, which is beneficial for rapid lithium-ion transport. This helps reduce the impedance of the cathode material, thereby improving the initial coulombic efficiency and discharge specific capacity of the battery.

[0048] This invention does not limit the method for achieving the sphericity of lithium-rich manganese-based material precursor particles. For example, by controlling different preparation processes, the selection and addition amount of each raw material during the preparation process, and the reaction conditions during the preparation process, the sphericity of the lithium-rich manganese-based material precursor can be within the above-mentioned range.

[0049] Specifically, the sphericity of the lithium-rich manganese-based material precursor of the present invention can be obtained by testing with imageJ software.

[0050] In one specific embodiment, the specific surface area of ​​the lithium-rich manganese-based material precursor is 20-40 m². 2 / g, for example, 20m 2 / g、22m 2 / g、24m 2 / g、26m 2 / g、28m 2 / g、30m 2 / g、32m 2 / g、34m 2 / g、36m 2 / g、38m 2 / g or 40m 2 / g etc. When the specific surface area of ​​the lithium-rich manganese-based material precursor is within the above range, the cathode material prepared from the lithium-rich manganese-based material precursor can be better wetted by the electrolyte, which is beneficial to the transport of lithium ions, reduces the impedance of the battery, and thus can improve the initial coulombic efficiency and discharge specific capacity of the battery.

[0051] This invention does not limit the method for achieving the specific surface area of ​​lithium-rich manganese-based material precursors. For example, by controlling the selection and addition amount of each raw material and the reaction conditions during the preparation process, the specific surface area of ​​the lithium-rich manganese-based material precursor can be within the above-mentioned range.

[0052] Specifically, the specific surface area of ​​the lithium-rich manganese-based material precursor of the present invention can be obtained by testing with an N2 physical adsorption-desorption instrument.

[0053] In one specific embodiment, the lithium-rich manganese-based material precursor includes primary particles and / or secondary particles formed from the primary particles; the primary particles have a particle size of 50-200 nm, for example, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 110 nm, 120 nm, 130 nm, 140 nm, 150 nm, 160 nm, 170 nm, 180 nm, 190 nm, or 200 nm; the secondary particles have a Dv10 of 1-2 μm, for example, 1 μm, 1.1 μm, 1.2 μm, 1.3 μm, 1.4 μm, 1.5 μm, 1.6 μm, or 1.7 μm. The micrometers for Dv10 and Dv50 are 1.8μm, 1.9μm, or 2μm. Dv50 is 6-15μm, for example, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, or 15μm. Dv90 is 15-25μm, for example, 15μm, 16μm, 17μm, 18μm, 19μm, 20μm, 21μm, 22μm, 23μm, 24μm, or 25μm. (Dv90-Dv10) / Dv50 is 0.6-1.5, for example, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, or 1.5.

[0054] The lithium-rich manganese-based material precursor of the present invention comprises secondary particles, wherein the Dv10, Dv50, Dv90, and (Dv90-D10) / Dv50 of the secondary particles are respectively within the aforementioned ranges, and the secondary particles are formed by the agglomeration of primary particles, the primary particles having a particle size of 50-200 nm. The low sodium content during the preparation of the precursor of the present invention is beneficial for homogeneous nucleation, resulting in spherical primary particles with a particle size in the range of 50-200 nm. These spherical primary particles can agglomerate to form secondary particles, the Dv10, Dv50, Dv90, and (Dv90-D10) / Dv50 of the formed secondary particles being respectively within the aforementioned ranges. When the particle sizes of primary and secondary particles are within the aforementioned range, the low surface energy of spherical particles allows the lithium-rich manganese-based precursor to decompose and generate carbon dioxide gas during the preparation of the cathode material. This facilitates the formation of uniform pores within the cathode material, enabling a more compact packing and increasing the compaction density. Furthermore, the reasonable particle size distribution of the lithium-rich manganese-based precursor allows it to be packed in a manner where large and small spheres fill each other, resulting in a higher compaction density and enabling more lithium ions to be transported within the same volume of battery, thereby increasing the battery's volumetric energy density.

[0055] The present invention does not limit the method for achieving the particle size of the primary and secondary particles of the lithium-rich manganese-based material precursor. For example, by controlling the selection and addition amount of each raw material and the reaction conditions during the preparation process, the particle size of the primary and secondary particles of the lithium-rich manganese-based material precursor can be within the above-mentioned range.

[0056] The particle size of the primary particles of the present invention can be obtained by measuring the measuring tools on an electron microscope; the Dv10, Dv50, and Dv90 of the secondary particles of the present invention can be obtained by testing with a Malvern particle size analyzer.

[0057] In one specific embodiment, the lithium-rich manganese-based material precursor belongs to the R-3c space group; preferably, the X-ray diffraction pattern of the lithium-rich manganese-based material precursor includes a diffraction peak (104) at 2θ of 30-32° and a diffraction peak at 2θ of 23-25°. Full width at half maximum (FWHM) of diffraction peak (104) (104) The diffraction peaks are at 0.1-0.5°. The ratio of the peak intensity of the diffraction peak (104) to the peak intensity of the diffraction peak. The range is 0.1-0.7, for example, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, or 0.7. When the ratio of the half-width at half-maximum (WHM) to the peak intensity of the lithium-rich manganese-based precursor is within the above range, it is beneficial to stabilize the layered structure of the cathode material, achieve lattice oxygen stability, and enable rapid lithium-ion insertion and migration. This allows lithium ions in the cathode material to migrate smoothly during charging and discharging, effectively improving the battery's initial coulombic efficiency and discharge specific capacity.

[0058] This invention does not limit the method for achieving the half-peak width and peak intensity ratio of lithium-rich manganese-based material precursors. For example, by controlling different preparation processes, the selection and addition amount of each raw material during the preparation process, and the reaction conditions during the preparation process, the half-peak width and peak intensity ratio of the lithium-rich manganese-based material precursors can be within the above-mentioned range.

[0059] In one specific embodiment, the method for preparing the lithium-rich manganese-based material precursor of the present invention includes the following steps:

[0060] A mixed solution A, including nickel, cobalt, manganese and metal salts, is mixed with a solution B, including low-sodium or ammonium raw materials, to obtain a precipitate. The precipitate is then calcined to obtain a lithium-rich manganese-based material precursor.

[0061] Specifically, nickel source, cobalt source, manganese source and metal salt are mixed and dissolved in a solvent to obtain mixed solution A; low sodium raw material or ammonium-containing raw material is dissolved in a solvent to obtain solution B; mixed solution A and solution B are mixed, and a precipitate is generated during the mixing process. The precipitate is washed, dried and then calcined to obtain lithium-rich manganese-based material precursor.

[0062] The metal salts of the present invention refer to salts comprising at least one of Ti, Cr, Mg, Zr, B, P, W, Si, Cu, Fe, and Ta.

[0063] The nickel source, cobalt source, manganese source, and metal salt of the present invention include at least one of sulfate, nitrate, and halide salt.

[0064] This invention does not limit the specific choice of solvent, which can be selected according to actual needs, such as water, ethanol, etc.

[0065] The low-sodium or ammonium-containing raw materials of the present invention include at least one of sodium bicarbonate, ammonium carbonate, ammonium bicarbonate, potassium carbonate, and potassium bicarbonate.

[0066] The total concentration of metal ions in the mixed solution A of the present invention is 0.1-5 mol / L, preferably 1.5-2.5 mol / L.

[0067] In the present invention, the molar concentration of low-sodium raw material or ammonium-containing raw material in solution B is 0.1-5 mol / L, preferably, the molar concentration of low-sodium raw material or ammonium-containing raw material is 1.5-2.5 mol / L.

[0068] The present invention does not limit the specific volume ratio of mixed solution A and solution B, and can be selected according to actual needs.

[0069] The present invention does not limit the specific parameters of the mixing process, and can be selected according to actual needs.

[0070] This invention does not limit the specific parameters of the washing and drying processes; they can be selected according to actual needs.

[0071] This invention does not limit the specific parameters of the calcination treatment, and can be selected according to actual needs.

[0072] The method for preparing lithium-rich manganese-based material precursors of this invention uses low-sodium or sodium-free raw materials, achieving minimal or no sodium introduction in the synthesis of the precursor. This results in a low sodium content in the synthesized precursor, enabling the synthesis of low-sodium cathode materials, thus suppressing water absorption and improving the initial coulombic efficiency and discharge specific capacity of the corresponding battery. Furthermore, the method uses ammonium-containing raw materials, which maintain the ammonia concentration in the preparation system during the preparation of the lithium-rich manganese-based material precursor, achieving co-precipitation of metals such as nickel, cobalt, and manganese, reducing the use of ammonia water, and achieving an environmentally friendly effect. In addition, the preparation process is simple and easy to implement, laying the foundation for the large-scale production of lithium-rich manganese-based material precursors.

[0073] This invention provides a cathode material, which is prepared by a method comprising the following steps:

[0074] The lithium-rich manganese-based precursor was calcined in an inert atmosphere to obtain a first intermediate; the first intermediate was mixed with a lithium source and calcined in an air atmosphere to obtain a cathode material.

[0075] Specifically, under an inert atmosphere, the lithium-rich manganese-based precursor is calcined to pre-decompose it. During calcination, a gas outlet pipe is connected to the tail of the furnace and then to water. Calcination is first carried out until no more bubbles are generated. Then, the gas outlet pipe is connected to clear limewater. The absence of precipitate indicates that pre-decomposition is complete and no further carbon dioxide is generated. The mixture is then cooled to room temperature to obtain the first intermediate. Next, under an air atmosphere, the first intermediate is mixed with a lithium source and then calcined. During calcination, a gas outlet pipe is connected to the tail of the furnace and then to water. Calcination is first carried out until no more bubbles are generated. Then, the gas outlet pipe is connected to clear limewater. The absence of precipitate indicates that calcination is complete and no further carbon dioxide is generated. The mixture is then cooled to room temperature, crushed, and sieved to obtain the cathode material.

[0076] The present invention does not limit the choice of inert atmosphere, and can be selected according to actual needs, such as nitrogen, argon, etc.

[0077] The lithium source of this invention includes lithium carbonate and / or lithium hydroxide.

[0078] This invention does not limit the specific parameters of crushing and sieving processes; they can be selected according to actual needs.

[0079] This invention does not limit the specific molar ratio of lithium-rich manganese-based material precursor to lithium source, and can be selected according to actual needs.

[0080] The calcination temperature of the present invention is 200℃-300℃, for example, 200℃, 210℃, 220℃, 230℃, 240℃, 250℃, 260℃, 270℃, 280℃, 290℃ or 300℃.

[0081] The calcination temperature of the present invention is 500℃-1000℃, for example, 500℃, 550℃, 600℃, 650℃, 700℃, 750℃, 800℃, 850℃, 900℃, 950℃ or 1000℃.

[0082] This invention prepares cathode materials using a two-stage calcination method. First, a lithium-rich manganese-based precursor is fully calcined in an inert gas atmosphere, allowing for the complete decomposition and oxidation of the transition metal oxide, resulting in a relatively regular structure. Then, it is calcined with a lithium source in air, facilitating the penetration of lithium oxide into the transition metal oxide and forming a dense cathode material with a well-defined crystalline structure. This method produces cathode materials with high compaction density, thereby improving the volumetric energy density of the battery. Furthermore, this preparation method is simple, low-cost, and environmentally friendly.

[0083] In one specific embodiment, the chemical formula of the positive electrode material is Li[Li a Ni b Co c Mn d M e The cathode material contains O2, where 0.1 ≤ a ≤ 0.3, 0 < b < 1, 0 < c < 1, 0 < d < 1, 0 < e < 1, and M is at least one of Ti, Cr, Mg, Zr, B, P, W, Si, Cu, Fe, and Ta. The mass percentage of sodium in the cathode material is 200-2000 ppm, for example, 200 ppm, 500 ppm, 800 ppm, 1000 ppm, 1200 ppm, 1500 ppm, 1800 ppm, or 2000 ppm. When the cathode material has a specific chemical formula and the mass percentage of sodium is within the above range, it can suppress the water absorption tendency of the cathode material, avoid side reactions between water and electrolyte, and thus improve the initial coulombic efficiency and discharge specific capacity of the battery.

[0084] This invention does not limit the method for achieving the mass percentage of sodium in the cathode material. For example, by controlling the selection of the process, the selection and addition amount of each raw material, and the reaction conditions during the preparation process, the mass percentage of sodium in the cathode material can be made to be within the above-mentioned range.

[0085] The mass percentage of sodium in the cathode material of the present invention can be obtained by ICP testing.

[0086] In one specific embodiment, the water content in the cathode material is 50-300 ppm by mass, for example, 50 ppm, 100 ppm, 150 ppm, 200 ppm, 250 ppm, or 300 ppm. When the water content in the cathode material is within the above range, the low water content can prevent side reactions in the battery, thereby improving the battery's initial coulombic efficiency and discharge specific capacity.

[0087] The mass percentage of water in the cathode material of the present invention can be obtained by testing with a moisture meter.

[0088] In one specific embodiment, the powder compaction density of the cathode material under 5 tons of pressure is 2.5-3.5 g / cc, for example, 2.5 g / cc, 2.6 g / cc, 2.7 g / cc, 2.8 g / cc, 2.9 g / cc, 3.0 g / cc, 3.1 g / cc, 3.2 g / cc, 3.3 g / cc, 3.4 g / cc, or 3.5 g / cc. When the powder compaction density of the cathode material is within the above range, there is more cathode material in the cathode sheet of the same volume of battery, which allows for the transport of more lithium ions, thereby improving the volumetric energy density of the battery.

[0089] In one specific embodiment, the specific surface area of ​​the cathode material is 1-4 m². 2 / g, for example, 1m 2 / g, 1.5m 2 / g、2m 2 / g, 2.5m 2 / g、3m 2 / g, 3.5m 2 / g or 4m 2 / g etc. When the specific surface area of ​​the cathode material is within the above range, the cathode material can be fully wetted by the electrolyte, allowing lithium ions to be efficiently transported between the cathode material and the electrolyte, reducing the battery impedance, and thus making the battery's initial coulombic efficiency and discharge specific capacity better.

[0090] In one specific embodiment, the Dv10 of the positive electrode material is 1-5 μm, for example, 1 μm, 1.2 μm, 1.4 μm, 1.6 μm, 1.8 μm, 2 μm, 2.2 μm, 2.4 μm, 2.6 μm, 2.8 μm, 3 μm, 3.2 μm, 3.4 μm, 3.6 μm, 3.8 μm, 4 μm, 4.2 μm, 4.4 μm, 4.6 μm, 4.8 μm, or 5 μm, etc., and the Dv50 is 4-12 μm, for example, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm. The particle size can be 12μm, etc., and Dv90 is 12-20μm, for example, 12μm, 12.5μm, 13μm, 13.5μm, 14μm, 14.5μm, 15μm, 15.5μm, 16μm, 16.5μm, 17μm, 17.5μm, 18μm, 18.5μm, 19μm, 19.5μm, or 20μm, etc., and (Dv90-Dv10) / Dv50 is 0.5-1.5, for example, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, or 1.5, etc. When the particle size of the cathode material is within the above range, the cathode material can be stacked in a gap-filling manner, thereby further improving the compaction density of the cathode material and making the volumetric energy density of the battery higher.

[0091] This invention does not limit the method for achieving the compaction density, specific surface area, and particle size of the cathode material. For example, by controlling the selection of the process, the selection and addition amount of each raw material during the preparation process, and the reaction conditions during the preparation process, the compaction density, specific surface area, and particle size of the cathode material can be within the above-mentioned range.

[0092] The compaction density of the cathode material of the present invention can be obtained by testing with a compaction density meter; the specific surface area of ​​the cathode material can be obtained by testing with an N2 physical adsorption-desorption meter; and the Dv10, Dv50, and Dv90 of the cathode material can be obtained by testing with a Malvern particle size analyzer.

[0093] In one specific embodiment, the sphericity of the cathode material particles is 60-95%, for example, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or 95%, etc.; Y = 97% - X / 1000 * (5~10%), where Y is the sphericity of the cathode material, %; X is the mass percentage of sodium in the cathode material, ppm. When the sphericity of the cathode material particles is within the above range, there are more transport channels and shorter transport paths for lithium ions in the cathode material, which is conducive to the rapid transport of lithium ions, resulting in better initial coulombic efficiency and discharge specific capacity of the battery. In addition, the sphericity of the cathode material particles and the sodium content satisfy the above relationship because a low sodium content in the preparation process of the cathode material is conducive to homogeneous nucleation in the preparation process of lithium-rich manganese-based material precursors, thereby improving the sphericity of the lithium-rich manganese-based material precursors, and correspondingly improving the sphericity of the cathode material, thus further improving the initial coulombic efficiency and discharge specific capacity of the battery.

[0094] This invention does not limit the method for achieving the sphericity of the cathode material. For example, by controlling the selection of the process, the selection and addition amount of each raw material during the preparation process, and the reaction conditions during the preparation process, the sphericity of the cathode material can be made to be within the above range.

[0095] The sphericity of the cathode material of the present invention can be obtained by testing with ImageJ software.

[0096] In one specific embodiment, the cathode material belongs to the C2 / m space group; preferably, the X-ray diffraction pattern of the cathode material includes a diffraction peak (003) at 2θ of 18-19°, a diffraction peak (104) at 2θ of 44.2-44.8°, a diffraction peak (006) at 2θ of 38.43°, and a diffraction peak (102) at 2θ of 38.53°; the full width at half maximum (FWHM) of the diffraction peak (003) is... (003)The cleavage angle is 0.01-0.1°; the ratio of the peak intensities of diffraction peak (003) and diffraction peak (104), I(003) / I(104), is 1.5-1.8, for example, 1.5, 1.6, 1.7 or 1.8, etc.; the cleavage angle of diffraction peak (006) and diffraction peak (102) is 0.3-0.6°. The cleavage angle of this invention refers to the angular change corresponding to the splitting phenomenon of the diffraction peak. When the cathode material exhibits the above four diffraction peaks, and the half-width at half-maximum, peak intensity ratio, and splitting angle of the diffraction peaks are within the above ranges, the cathode material has high crystallinity, exhibits a stable layered structure and low Li / Ni mixing ratio, and has low sodium impurity content. This can prevent the residual alkali on the surface of the cathode material from absorbing water and avoid the generation of side reactions on the surface of the cathode material. This inhibits the thickening of the residual alkali layer and the increase of the Li / Ni mixing ratio in the cathode material caused by water absorption and Li / H exchange, thereby enabling rapid lithium ion insertion / extraction and effectively improving the battery's initial coulombic efficiency and discharge specific capacity.

[0097] This invention provides a battery comprising the above-described cathode material. The battery provided by this invention exhibits excellent initial coulombic efficiency, discharge specific capacity, and volumetric energy density.

[0098] In one specific embodiment, the battery includes a positive electrode, a negative electrode, a separator, and an electrolyte, specifically:

[0099] The positive electrode sheet includes a positive active layer and a positive current collector, which is generally aluminum foil. The positive active layer includes the positive electrode material, conductive agent, and binder provided by this invention.

[0100] The negative electrode sheet includes a negative current collector and a negative active material layer. The negative active material layer includes a negative active material, a conductive agent, and a binder. The negative current collector is generally aluminum foil, and the negative active material is selected from one or more of carbonaceous materials, silicon carbide materials, alloy materials, and sodium-containing metal composite oxides.

[0101] This invention does not limit the selection of conductive agents and binders in the positive and negative active layers. For example, the conductive agents and binders can be conventional materials in the art, and can be specifically set according to needs. This invention does not limit the preparation method of the positive and negative electrode sheets. They can be prepared using conventional techniques in the art or other preparation processes, and can be specifically selected according to requirements.

[0102] The separator is a separator known in the art that can be used in batteries and is stable to the electrolyte used. It may include one or more of polyolefins, aromatic polyamides, polytetrafluoroethylene, and polyethersulfone, and may be configured as needed.

[0103] Electrolytes are those known in the art that can be used in batteries to enhance their electrochemical performance, including lithium salts and organic solvents, which can be specifically configured as needed.

[0104] The present invention will be further described in detail below through specific embodiments.

[0105] Example 1

[0106] The preparation process of the lithium-rich manganese-based precursor and cathode material provided in this embodiment includes the following steps:

[0107] 1. Nickel sulfate, cobalt sulfate, manganese sulfate, and magnesium sulfate are mixed in a molar ratio of 3:3:3:1 and dissolved in water to obtain mixed solution A, in which the total molar concentration of metal ions is 2 mol / L;

[0108] 2. Dissolve ammonium carbonate in water to obtain solution B, wherein the molar concentration of ammonium carbonate is 2 mol / L;

[0109] 3. Mix solution A and solution B at a volume ratio of 1:1 to obtain a precipitate. Wash and dry the precipitate, and then bake the precipitate to obtain a lithium-rich manganese-based material precursor. The baking temperature is 110℃ and the baking time is 24h.

[0110] 4. Under a nitrogen atmosphere, the lithium-rich manganese-based material precursor was calcined at 200°C. During calcination, a gas outlet pipe was connected to the tail of the furnace and connected to water. The calcination was first carried out until no bubbles were generated. Then the gas outlet pipe was connected to clear lime water. If no precipitate was generated, it indicated that the pre-decomposition was completed. The temperature was then lowered to room temperature to obtain the first intermediate.

[0111] 5. In an air atmosphere, the first intermediate is mixed with lithium carbonate. After the mixture is evenly mixed, it is calcined at 850°C. During calcination, a gas outlet pipe is connected to the tail of the furnace and connected to water. First, calcination is carried out until no bubbles are generated. Then, the gas outlet pipe is connected to clear lime water. If no precipitate is generated, it indicates that the calcination is complete. Then, the temperature is lowered to room temperature, crushed, and sieved to obtain the cathode material.

[0112] The molar ratio of lithium source to lithium-rich manganese-based material precursor is 1.2:1.

[0113] Example 2

[0114] The preparation process of the lithium-rich manganese-based precursor and cathode material provided in this embodiment includes the following steps:

[0115] 1. Nickel sulfate, cobalt sulfate, manganese sulfate, and magnesium sulfate are mixed in a molar ratio of 3:3:3:1 and dissolved in water to obtain mixed solution A, in which the total molar concentration of metal ions is 2 mol / L;

[0116] 2. Dissolve ammonium bicarbonate in water to obtain solution B, wherein the molar concentration of ammonium bicarbonate is 2 mol / L;

[0117] 3. Mix solution A and solution B at a volume ratio of 1:1 to obtain a precipitate. Wash and dry the precipitate, and then bake the precipitate to obtain a lithium-rich manganese-based material precursor. The baking temperature is 110℃ and the baking time is 24h.

[0118] 4. Under a nitrogen atmosphere, the lithium-rich manganese-based material precursor was calcined at 200°C. During calcination, a gas outlet pipe was connected to the tail of the furnace and connected to water. The calcination was first carried out until no bubbles were generated. Then the gas outlet pipe was connected to clear lime water. If no precipitate was generated, it indicated that the pre-decomposition was completed. The temperature was then lowered to room temperature to obtain the first intermediate.

[0119] 5. In an air atmosphere, the first intermediate is mixed with lithium carbonate. After the mixture is evenly mixed, it is calcined at 850°C. During calcination, a gas outlet pipe is connected to the tail of the furnace and connected to water. First, calcination is carried out until no bubbles are generated. Then, the gas outlet pipe is connected to clear lime water. If no precipitate is generated, it indicates that the calcination is complete. Then, the temperature is lowered to room temperature, crushed, and sieved to obtain the cathode material.

[0120] The molar ratio of lithium source to lithium-rich manganese-based material precursor is 1.2:1.

[0121] Example 3

[0122] The preparation process of the lithium-rich manganese-based precursor and cathode material provided in this embodiment includes the following steps:

[0123] 1. Nickel sulfate, cobalt sulfate, manganese sulfate, and magnesium sulfate are mixed in a molar ratio of 3:3:3:1 and dissolved in water to obtain mixed solution A, in which the total molar concentration of metal ions is 2 mol / L;

[0124] 2. Dissolve sodium bicarbonate in water to obtain solution B, wherein the molar concentration of sodium bicarbonate is 2 mol / L;

[0125] 3. Mix solution A and solution B at a volume ratio of 1:1 to obtain a precipitate. Wash and dry the precipitate, and then bake the precipitate to obtain a lithium-rich manganese-based material precursor. The baking temperature is 110℃ and the baking time is 24h.

[0126] 4. Under a nitrogen atmosphere, the lithium-rich manganese-based material precursor was calcined at 200°C. During calcination, a gas outlet pipe was connected to the tail of the furnace and connected to water. The calcination was first carried out until no bubbles were generated. Then the gas outlet pipe was connected to clear lime water. If no precipitate was generated, it indicated that the pre-decomposition was completed. The temperature was then lowered to room temperature to obtain the first intermediate.

[0127] 5. In an air atmosphere, the first intermediate is mixed with lithium carbonate. After the mixture is evenly mixed, it is calcined at 850°C. During calcination, a gas outlet pipe is connected to the tail of the furnace and connected to water. First, calcination is carried out until no bubbles are generated. Then, the gas outlet pipe is connected to clear lime water. If no precipitate is generated, it indicates that the calcination is complete. Then, the temperature is lowered to room temperature, crushed, and sieved to obtain the cathode material.

[0128] The molar ratio of lithium source to lithium-rich manganese-based material precursor is 1.2:1.

[0129] Example 4

[0130] The preparation process of the lithium-rich manganese-based precursor and cathode material provided in this embodiment includes the following steps:

[0131] 1. Nickel sulfate, cobalt sulfate, manganese sulfate, and magnesium sulfate are mixed in a molar ratio of 3:3:3:1 and dissolved in water to obtain mixed solution A, in which the total molar concentration of metal ions is 2 mol / L;

[0132] 2. Dissolve ammonium carbonate in water to obtain solution B, wherein the molar concentration of ammonium carbonate is 2 mol / L;

[0133] 3. Mix solution A and solution B at a volume ratio of 1:1 to obtain a precipitate. Wash and dry the precipitate, and then bake the precipitate to obtain a lithium-rich manganese-based material precursor. The baking temperature is 150℃ and the baking time is 24h.

[0134] 4. Under a nitrogen atmosphere, the lithium-rich manganese-based material precursor was calcined at 200°C. During calcination, a gas outlet pipe was connected to the tail of the furnace and connected to water. The calcination was first carried out until no bubbles were generated. Then the gas outlet pipe was connected to clear lime water. If no precipitate was generated, it indicated that the pre-decomposition was completed. The temperature was then lowered to room temperature to obtain the first intermediate.

[0135] 5. In an air atmosphere, the first intermediate is mixed with lithium carbonate. After the mixture is evenly mixed, it is calcined at 900°C. During calcination, a gas outlet pipe is connected to the tail of the furnace and connected to water. First, calcination is carried out until no bubbles are generated. Then, the gas outlet pipe is connected to clear lime water. If no precipitate is generated, it indicates that the calcination is complete. Then, the temperature is lowered to room temperature, crushed, and sieved to obtain the cathode material.

[0136] The molar ratio of lithium source to lithium-rich manganese-based material precursor is 1.2:1.

[0137] Example 5

[0138] The preparation process of the lithium-rich manganese-based precursor and cathode material provided in this embodiment includes the following steps:

[0139] 1. Nickel sulfate, cobalt sulfate, manganese sulfate, and magnesium sulfate are mixed in a molar ratio of 3:3:3:1 and dissolved in water to obtain mixed solution A, in which the total molar concentration of metal ions is 2 mol / L;

[0140] 2. Dissolve ammonium carbonate in water to obtain solution B, wherein the molar concentration of ammonium carbonate is 4 mol / L;

[0141] 3. Mix solution A and solution B at a volume ratio of 1:1 to obtain a precipitate. Wash and dry the precipitate, and then bake the precipitate to obtain a lithium-rich manganese-based material precursor. The baking temperature is 110℃ and the baking time is 24h.

[0142] 4. Under a nitrogen atmosphere, the lithium-rich manganese-based material precursor was calcined at 200°C. During calcination, a gas outlet pipe was connected to the tail of the furnace and connected to water. The calcination was first carried out until no bubbles were generated. Then the gas outlet pipe was connected to clear lime water. If no precipitate was generated, it indicated that the pre-decomposition was completed. The temperature was then lowered to room temperature to obtain the first intermediate.

[0143] 5. In an air atmosphere, the first intermediate is mixed with lithium carbonate. After the mixture is evenly mixed, it is calcined at 850°C. During calcination, a gas outlet pipe is connected to the tail of the furnace and connected to water. First, calcination is carried out until no bubbles are generated. Then, the gas outlet pipe is connected to clear lime water. If no precipitate is generated, it indicates that the calcination is complete. Then, the temperature is lowered to room temperature, crushed, and sieved to obtain the cathode material.

[0144] The molar ratio of lithium source to lithium-rich manganese-based material precursor is 1.2:1.

[0145] Example 6

[0146] The preparation process of the lithium-rich manganese-based precursor and cathode material provided in this embodiment includes the following steps:

[0147] 1. Nickel sulfate, cobalt sulfate, manganese sulfate, and magnesium sulfate are mixed in a molar ratio of 3:3:3:1 and dissolved in water to obtain mixed solution A, in which the total molar concentration of metal ions is 4 mol / L;

[0148] 2. Dissolve ammonium carbonate in water to obtain solution B, wherein the molar concentration of ammonium carbonate is 2 mol / L;

[0149] 3. Mix solution A and solution B at a volume ratio of 1:1 to obtain a precipitate. Wash and dry the precipitate, and then bake the precipitate to obtain a lithium-rich manganese-based material precursor. The baking temperature is 110℃ and the baking time is 24h.

[0150] 4. Under a nitrogen atmosphere, the lithium-rich manganese-based material precursor was calcined at 200°C. During calcination, a gas outlet pipe was connected to the tail of the furnace and connected to water. The calcination was first carried out until no bubbles were generated. Then the gas outlet pipe was connected to clear lime water. If no precipitate was generated, it indicated that the pre-decomposition was completed. The temperature was then lowered to room temperature to obtain the first intermediate.

[0151] 5. In an air atmosphere, the first intermediate is mixed with lithium carbonate. After the mixture is evenly mixed, it is calcined at 850°C. During calcination, a gas outlet pipe is connected to the tail of the furnace and connected to water. First, calcination is carried out until no bubbles are generated. Then, the gas outlet pipe is connected to clear lime water. If no precipitate is generated, it indicates that the calcination is complete. Then, the temperature is lowered to room temperature, crushed, and sieved to obtain the cathode material.

[0152] The molar ratio of lithium source to lithium-rich manganese-based material precursor is 1.2:1.

[0153] Example 7

[0154] The preparation process of the lithium-rich manganese-based precursor and cathode material provided in this embodiment includes the following steps:

[0155] 1. Nickel sulfate, cobalt sulfate, manganese sulfate, and magnesium sulfate are mixed in a molar ratio of 3:3:3:1 and dissolved in water to obtain mixed solution A, in which the total molar concentration of metal ions is 2 mol / L;

[0156] 2. Dissolve ammonium carbonate in water to obtain solution B, wherein the molar concentration of ammonium carbonate is 2 mol / L;

[0157] 3. Mix solution A and solution B at a volume ratio of 1:2 to obtain a precipitate. Wash and dry the precipitate, and then bake it to obtain a lithium-rich manganese-based material precursor. The baking temperature is 110℃ and the baking time is 24h.

[0158] 4. Under a nitrogen atmosphere, the lithium-rich manganese-based material precursor was calcined at 200°C. During calcination, a gas outlet pipe was connected to the tail of the furnace and connected to water. The calcination was first carried out until no bubbles were generated. Then the gas outlet pipe was connected to clear lime water. If no precipitate was generated, it indicated that the pre-decomposition was completed. The temperature was then lowered to room temperature to obtain the first intermediate.

[0159] 5. In an air atmosphere, the first intermediate is mixed with lithium carbonate. After the mixture is evenly mixed, it is calcined at 850°C. During calcination, a gas outlet pipe is connected to the tail of the furnace and connected to water. First, calcination is carried out until no bubbles are generated. Then, the gas outlet pipe is connected to clear lime water. If no precipitate is generated, it indicates that the calcination is complete. Then, the temperature is lowered to room temperature, crushed, and sieved to obtain the cathode material.

[0160] The molar ratio of lithium source to lithium-rich manganese-based material precursor is 1.2:1.

[0161] Example 8

[0162] The preparation process of the lithium-rich manganese-based precursor and cathode material provided in this embodiment includes the following steps:

[0163] 1. Nickel sulfate, cobalt sulfate, manganese sulfate, and magnesium sulfate are mixed in a molar ratio of 3:3:3:1 and dissolved in water to obtain mixed solution A, in which the total molar concentration of metal ions is 2 mol / L;

[0164] 2. Dissolve ammonium carbonate in water to obtain solution B, wherein the molar concentration of ammonium carbonate is 2 mol / L;

[0165] 3. Mix solution A and solution B at a volume ratio of 1:1 to obtain a precipitate. Wash and dry the precipitate, and then bake the precipitate to obtain a lithium-rich manganese-based material precursor. The baking temperature is 110℃ and the baking time is 24h.

[0166] 4. Under a nitrogen atmosphere, the lithium-rich manganese-based material precursor was calcined at 200°C. During calcination, a gas outlet pipe was connected to the tail of the furnace and connected to water. The calcination was first carried out until no bubbles were generated. Then the gas outlet pipe was connected to clear lime water. If no precipitate was generated, it indicated that the pre-decomposition was completed. The temperature was then lowered to room temperature to obtain the first intermediate.

[0167] 5. In an air atmosphere, the first intermediate is mixed with lithium carbonate. After the mixture is evenly mixed, it is calcined at 850°C. During calcination, a gas outlet pipe is connected to the tail of the furnace and connected to water. First, calcination is carried out until no bubbles are generated. Then, the gas outlet pipe is connected to clear lime water. If no precipitate is generated, it indicates that the calcination is complete. Then, the temperature is lowered to room temperature, crushed, and sieved to obtain the cathode material.

[0168] The molar ratio of lithium source to lithium-rich manganese-based material precursor is 1.4:1.

[0169] Example 9

[0170] The preparation process of the lithium-rich manganese-based precursor and cathode material provided in this embodiment includes the following steps:

[0171] 1. Nickel sulfate, cobalt sulfate, manganese sulfate, and magnesium sulfate are mixed in a molar ratio of 3:3:3:1 and dissolved in water to obtain mixed solution A, in which the total molar concentration of metal ions is 2 mol / L;

[0172] 2. Dissolve ammonium carbonate in water to obtain solution B, wherein the molar concentration of ammonium carbonate is 2 mol / L;

[0173] 3. Mix solution A and solution B at a volume ratio of 1:1 to obtain a precipitate. Wash and dry the precipitate, and then bake the precipitate to obtain a lithium-rich manganese-based material precursor. The baking temperature is 110℃ and the baking time is 24h.

[0174] 4. Under a nitrogen atmosphere, the lithium-rich manganese-based material precursor was calcined at 200°C. During calcination, a gas outlet pipe was connected to the tail of the furnace and connected to water. The calcination was first carried out until no bubbles were generated. Then the gas outlet pipe was connected to clear lime water. If no precipitate was generated, it indicated that the pre-decomposition was completed. The temperature was then lowered to room temperature to obtain the first intermediate.

[0175] 5. In an air atmosphere, the first intermediate is mixed with lithium carbonate. After the mixture is evenly mixed, it is calcined at 950°C. During calcination, a gas outlet pipe is connected to the tail of the furnace and connected to water. First, calcination is carried out until no bubbles are generated. Then, the gas outlet pipe is connected to clear lime water. If no precipitate is generated, it indicates that the calcination is complete. Then, the temperature is lowered to room temperature, crushed, and sieved to obtain the cathode material.

[0176] The molar ratio of lithium source to lithium-rich manganese-based material precursor is 1.2:1.

[0177] Example 10

[0178] The preparation process of the lithium-rich manganese-based precursor and cathode material provided in this embodiment includes the following steps:

[0179] 1. Nickel sulfate, cobalt sulfate, manganese sulfate, and magnesium sulfate are mixed in a molar ratio of 3:3:3:1 and dissolved in water to obtain mixed solution A, in which the total molar concentration of metal ions is 2 mol / L;

[0180] 2. Dissolve ammonium carbonate in water to obtain solution B, wherein the molar concentration of ammonium carbonate is 2 mol / L;

[0181] 3. Mix solution A and solution B at a volume ratio of 1:1 to obtain a precipitate. Wash and dry the precipitate, and then calcine the precipitate to obtain a lithium-rich manganese-based material precursor. The calcination temperature is 110℃ and the calcination time is 24 hours.

[0182] 4. Under a nitrogen atmosphere, the lithium-rich manganese-based material precursor was calcined at 200°C. During calcination, a gas outlet pipe was connected to the tail of the furnace and connected to water. The calcination was first carried out until no bubbles were generated. Then the gas outlet pipe was connected to clear lime water. If no precipitate was generated, it indicated that the pre-decomposition was completed. The temperature was then lowered to room temperature to obtain the first intermediate.

[0183] 5. In an air atmosphere, the first intermediate is mixed with lithium carbonate. After the mixture is evenly mixed, it is calcined at 650°C. During calcination, a gas outlet pipe is connected to the tail of the furnace and connected to water. First, calcination is carried out until no bubbles are generated. Then, the gas outlet pipe is connected to clear lime water. If no precipitate is generated, it indicates that the calcination is complete. Then, the temperature is lowered to room temperature, crushed, and sieved to obtain the cathode material.

[0184] The molar ratio of lithium-rich manganese-based precursor to lithium source is 1.2:1.

[0185] Comparative Example 1

[0186] The preparation process of the lithium-rich manganese-based precursor and cathode material provided in this comparative example includes the following steps:

[0187] 1. Nickel sulfate, cobalt sulfate, manganese sulfate, and magnesium sulfate are mixed in a molar ratio of 3:3:3:1 and dissolved in water to obtain mixed solution A, in which the total molar concentration of metal ions is 2 mol / L;

[0188] 2. Dissolve sodium carbonate in water to obtain solution B, wherein the molar concentration of sodium carbonate is 2 mol / L;

[0189] 3. Mix solution A and solution B at a volume ratio of 1:1 to obtain a precipitate. Wash and dry the precipitate, and then bake the precipitate to obtain a lithium-rich manganese-based material precursor. The baking temperature is 110℃ and the baking time is 24h.

[0190] 4. Under a nitrogen atmosphere, the lithium-rich manganese-based material precursor was calcined at 200°C. During calcination, a gas outlet pipe was connected to the tail of the furnace and connected to water. The calcination was first carried out until no bubbles were generated. Then the gas outlet pipe was connected to clear lime water. If no precipitate was generated, it indicated that the pre-decomposition was completed. The temperature was then lowered to room temperature to obtain the first intermediate.

[0191] 5. In an air atmosphere, the first intermediate is mixed with lithium carbonate. After the mixture is evenly mixed, it is calcined at 850°C. During calcination, a gas outlet pipe is connected to the tail of the furnace and connected to water. First, calcination is carried out until no bubbles are generated. Then, the gas outlet pipe is connected to clear lime water. If no precipitate is generated, it indicates that the calcination is complete. Then, the temperature is lowered to room temperature, crushed, and sieved to obtain the cathode material.

[0192] The molar ratio of lithium source to lithium-rich manganese-based material precursor is 1.2:1.

[0193] Table 1

[0194]

[0195]

[0196]

[0197] Experimental Example 1

[0198] The lithium-rich manganese-based material precursors of the examples and comparative examples were subjected to ICP testing to obtain the mass percentage content of sodium in the lithium-rich manganese-based material precursors, as shown in Table 2.

[0199] The sphericity of the lithium-rich manganese-based material precursors in the examples and comparative examples was tested using imageJ software, as shown in Table 2.

[0200] The lithium-rich manganese-based material precursors of the examples and comparative examples were subjected to N2 physical adsorption-desorption tests to obtain the specific surface area of ​​the lithium-rich manganese-based material precursors, as shown in Table 2.

[0201] The size of the primary particles of the lithium-rich manganese-based material precursors of the examples and comparative examples was measured by electron microscopy to obtain the particle size of the primary particles; the particle size of the secondary particles of the lithium-rich manganese-based material precursors of the examples and comparative examples was tested to obtain the Dv10, Dv50 and Dv90, as shown in Table 2.

[0202] XRD tests were performed on the lithium-rich manganese-based material precursors of the examples and comparative examples to obtain the full width at half maximum (FWHM). (104) and diffraction peaks The ratio of the peak intensity of the diffraction peak (104) to the peak intensity of the diffraction peak. See Table 2.

[0203] The cathode materials of the examples and comparative examples were subjected to ICP and moisture meter tests to obtain the mass percentage content of sodium and moisture in the cathode materials, as shown in Table 3.

[0204] The cathode materials of the examples and comparative examples were subjected to compaction tests using a compaction density meter to obtain the powder compaction density of the cathode materials under a pressure of 5 tons, as shown in Table 3.

[0205] The cathode materials of the examples and comparative examples were subjected to N2 physical adsorption-desorption tests to obtain the specific surface area of ​​the cathode materials, as shown in Table 3.

[0206] The particle size of the cathode materials in the examples and comparative examples was tested to obtain the Dv10, Dv50 and Dv90 of the cathode materials, as shown in Table 3.

[0207] The sphericity of the cathode materials in the examples and comparative examples was tested using ImageJ software, and the sphericity of the cathode materials was obtained, as shown in Table 3.

[0208] XRD tests were performed on the cathode materials of the examples and comparative examples to obtain the full width at half maximum (FWHM). (003) The ratio of peak intensity of diffraction peak (003) to diffraction peak (104) I(003) / I(104), and the splitting angle of diffraction peak (006) and diffraction peak (102) are shown in Table 3.

[0209] Figure 1 The graph shows the discharge capacity of the batteries in Examples 1-3 and Comparative Example 1 after 50 cycles. Figure 1 It can be seen that Example 1 has the highest discharge specific capacity, reaching 249.6 mAh g. -1 .

[0210] Figure 2 The image shown is the XRD pattern of the lithium-rich manganese-based material precursor of Example 1. Figure 2 It can be seen that the XRD characteristics of the lithium-rich manganese-based material precursor are typical R-3c space group configurations, with the main peak crystal plane index being (104), 2θ located at 31.768°, and the full width at half maximum (FWHM) being [missing information]. (104) The value is 0.4°; the crystal plane index of the second strongest peak is 2θ is located at 24.49°; the intensity ratio of the two main peaks in the lithium-rich manganese-based material precursor. It is 0.3.

[0211] Figure 3 The image shows the XRD pattern of the cathode material in Example 1. Figure 3 It can be seen that the XRD characteristics of the cathode material are typical C2 / m space group configuration, with the main peak crystal plane index being (003), 2θ located at 18.69°, and a full width at half maximum (FWHM). (003) The second strongest peak crystal plane index is (104), and 2θ is located at 44.53°; the ratio of the main peak intensity I(003) / I(104) is 1.6; the splitting angle of (006) and (102) is 0.5°.

[0212] Figure 4 Here is a SEM image of the lithium-rich manganese-based material precursor from Example 1. Figure 4 It can be seen that the primary particles of the lithium-rich manganese-based material precursor are 100 nm spherical particles, and the Dv50 of the secondary particles is 8.2 μm.

[0213] Figure 5 Here is a SEM image of the lithium-rich manganese-based material precursor from Example 1. Figure 5 It can be seen that the sphericity of the lithium-rich manganese-based material precursor particles, calculated by Imagine, is 80%.

[0214] Table 2

[0215]

[0216]

[0217] Table 3

[0218]

[0219]

[0220] Experimental Example 2

[0221] The positive electrode materials prepared in the above examples and comparative examples were mixed with conductive carbon and polyvinylidene fluoride at a mass ratio of 8:1:1 to obtain a positive electrode active layer slurry. This positive electrode active layer slurry was then coated onto the surface of the positive electrode current collector aluminum foil, with a coating surface density of 10 g / cm³. 2 The cathode material is dried at 120℃ for 80 minutes, then rolled and formed into a sheet with a compaction density of 2.8 g / cm³. 3 The positive electrode is assembled with a lithium sheet, a cellulose separator, and a conventional lithium hexafluorophosphate electrolyte to form a coin cell. The electrolyte comprises 12% lithium hexafluorophosphate, 83% organic solvent, and 5% additives. The organic solvents include EC (ethylene carbonate), DMC (dimethyl carbonate), and diethyl carbonate (DEC). The additives include one or more of nitrile compounds, vinylene carbonate, and 1,3-propenesulfonate lactone.

[0222] The coin cells underwent their first coulombic efficiency test and capacity and discharge specific capacity tests:

[0223] First Coulombic Efficiency: At 25°C, with a charge-discharge voltage window of 2-4.8V, charging at 0.1C and discharging at 0.1C, the discharge capacity at 0.1C is C1, and the charge capacity at 0.1C is C2. Then, the first Coulombic efficiency (%) = C1 / C2.

[0224] Discharge specific capacity: Charge at a constant current rate of 0.1C until the voltage reaches the cutoff voltage of 4.8V, and then charge at a constant voltage under the cutoff voltage condition until the current is less than 0.05C. The charging capacity at this time is recorded as the first charge capacity. After resting for 5 minutes, discharge at a constant current rate of 0.1C until the voltage reaches 2V. Repeat the cycle 50 times. The discharge capacity of the 50th cycle is the discharge specific capacity.

[0225] Volumetric energy density: The specific capacity of a battery is measured using volumetric energy density, which is calculated as: Specific capacity (mAh / g) * Voltage (V) * Electrode compaction density (g / cm³) 3 ).

[0226] The test results are shown in Table 4.

[0227] Table 4

[0228]

[0229] Table 4 shows that, comparing Examples 1-10 with Comparative Example 1, it was found that when the sodium content in the lithium-rich manganese-based material precursor is in the range of 200-3000 ppm, the water absorption tendency of the precursor can be suppressed, and the water absorption of the corresponding cathode material can also be suppressed. This avoids side reactions between water and electrolyte, thereby improving the initial coulombic efficiency and discharge specific capacity of the battery. Furthermore, controlling the sphericity, specific surface area, particle size, and diffraction peaks of the lithium-rich manganese-based material precursor can further improve the initial coulombic efficiency and discharge specific capacity of the battery. In addition, when the sodium content in the cathode material prepared based on the lithium-rich manganese-based material precursor is in the range of 200-2000 ppm, the water absorption tendency of the cathode material is suppressed, which can further improve the initial coulombic efficiency and discharge specific capacity of the battery. Similarly, by limiting the powder compaction density, specific surface area, particle size, sphericity, and diffraction peaks of the cathode material, the battery's initial coulombic efficiency and discharge specific capacity are improved.

[0230] In summary, the lithium-rich manganese-based precursor and cathode material provided by this invention can significantly improve the initial coulombic efficiency and discharge specific capacity of lithium-ion batteries.

[0231] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A lithium-rich manganese-based material precursor, characterized in that, The chemical formula of the lithium-rich manganese-based material precursor is Ni. x Co y Mn z M u CO3; Wherein, 0 < x < 1, 0 < y < 1, 0 < z < 1, 0 < u < 1, and M includes at least one of Ti, Cr, Mg, Zr, B, P, W, Si, Cu, Fe, and Ta; The sodium content in the lithium-rich manganese-based material precursor is 200-3000 ppm by mass.

2. The lithium-rich manganese-based material precursor according to claim 1, characterized in that, The sphericity of the lithium-rich manganese-based material precursor particles is 60-95%. And / or, the specific surface area of ​​the lithium-rich manganese-based material precursor is 20-40 m². 2 / g.

3. The lithium-rich manganese-based material precursor according to claim 1 or 2, characterized in that, The lithium-rich manganese-based material precursor includes primary particles and / or secondary particles formed from the primary particles. The primary particles have a particle size of 50-200 nm; the secondary particles have a Dv10 of 1-2 μm, a Dv50 of 6-15 μm, a Dv90 of 15-25 μm, and a (Dv90-Dv10) / Dv50 ratio of 0.6-1.

5.

4. The lithium-rich manganese-based material precursor according to any one of claims 1-3, characterized in that, The lithium-rich manganese-based material precursor belongs to the R-3c space group; Preferably, the X-ray diffraction pattern of the lithium-rich manganese-based material precursor includes a diffraction peak (104) at 2θ of 30-32° and a diffraction peak at 2θ of 23-25°. Full width at half maximum (FWHM) of diffraction peak (104) (104) The diffraction peaks are at 0.1-0.5°. The ratio of the peak intensity of the diffraction peak (104) to I / I(104) is 0.1-0.

7.

5. A positive electrode material, characterized in that, The cathode material is prepared by a method including the following steps: In an inert atmosphere, the lithium-rich manganese-based material precursor according to any one of claims 1-4 is calcined to obtain a first intermediate; in an air atmosphere, the first intermediate is mixed with a lithium source and calcined to obtain the cathode material.

6. The cathode material according to claim 5, characterized in that, The chemical formula of the cathode material is Li[Li] a Ni b Co c Mn d M e O2, wherein 0.1≤a≤0.3, 0<b<1, 0<c<1, 0<d<1, 0<e<1, and M includes at least one of Ti, Cr, Mg, Zr, B, P, W, Si, Cu, Fe, and Ta; The sodium content in the cathode material is 200-2000 ppm by mass.

7. The cathode material according to claim 5 or 6, characterized in that, The mass percentage of water in the cathode material is 50-300 ppm; And / or, the powder compaction density of the positive electrode material under 5 tons of pressure is 2.5-3.5 g / cc; And / or, the specific surface area of ​​the positive electrode material is 1-4 m². 2 / g; And / or, the positive electrode material has a Dv10 of 1-5 μm, a Dv50 of 4-12 μm, a Dv90 of 12-20 μm, and a (Dv90-Dv10) / Dv50 ratio of 0.5-1.

5.

8. The cathode material according to any one of claims 5-7, characterized in that, The sphericity of the positive electrode material particles is 60-95%; Y=97%-X / 1000*(5~10%), Wherein, Y is the sphericity of the cathode material, %; and X is the mass percentage of sodium in the cathode material, ppm.

9. The cathode material according to any one of claims 5-8, characterized in that, The cathode material belongs to the C2 / m space group; Preferably, the X-ray diffraction pattern of the cathode material includes a diffraction peak (003) at 2θ of 18-19°, a diffraction peak (104) at 2θ of 44.2-44.8°, a diffraction peak (006) at 2θ of 38.43°, and a diffraction peak (102) at 2θ of 38.53°; the full width at half maximum (FWHM) of the diffraction peak (003) is... (003) It is 0.01-0.1°; The ratio of the peak intensities of diffraction peak (003) and diffraction peak (104), I(003) / I(104), is 1.5-1.8; The splitting angles of the diffraction peaks (006) and (102) are 0.3-0.6°.

10. A battery, characterized in that, The battery comprises the positive electrode material as described in any one of claims 5-8.

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