CN-121974410-A - Preparation method of nickel lithium phosphate coated nickel lithium manganate positive electrode material

CN121974410ACN 121974410 ACN121974410 ACN 121974410ACN-121974410-A

Abstract

The invention discloses a preparation method of a nickel lithium phosphate coated nickel lithium manganate positive electrode material, which comprises the steps of uniformly mixing a nickel lithium manganate precursor and a lithium source, obtaining nickel lithium manganate monocrystal particles through sintering, mixing the nickel lithium manganate monocrystal particles with a phosphate solution to form a nickel-containing phosphate sediment, and performing secondary sintering under a protective atmosphere to obtain the nickel lithium phosphate coated nickel lithium manganate positive electrode material. The method can improve the initial capacity and the cycle performance of the nickel lithium phosphate coated nickel lithium manganate anode material, and has the advantages of simple preparation steps, wide material sources, low cost and more contribution to popularization and application in production practice.

Inventors

WANG CHANGYIN
YI XIN
LIU HAO
WU TINGTING
ZHANG QIAN
Zheng Ganyang

Assignees

贵州大龙汇成新材料有限公司

Dates

Publication Date: 20260505
Application Date: 20251231

Claims (10)

1. The preparation method of the nickel lithium phosphate coated nickel lithium manganate positive electrode material comprises the following steps of uniformly mixing a nickel lithium manganate precursor material and a lithium source material according to stoichiometric ratio, obtaining nickel lithium manganate monocrystal particles through sintering, mixing the nickel lithium manganate monocrystal particles with a phosphate solution, enabling phosphate to react with a small amount of dissolved nickel on the surfaces of the nickel lithium manganate particles to form nickel-containing phosphate sediment, performing secondary sintering in protective atmosphere, and further reacting to generate nickel lithium phosphate on the surfaces of the nickel lithium manganate particles to obtain the nickel lithium manganate coated nickel lithium manganate positive electrode material.
2. The method for preparing a lithium nickel phosphate coated lithium nickel manganese oxide positive electrode material according to claim 1, wherein the sintering comprises at least one early slow low temperature sintering, one intermediate crushing and at least one later slow high temperature sintering in order to form sharp corner passivated lithium nickel manganese oxide single crystal particles.
3. The preparation method of the nickel lithium phosphate coated lithium nickel manganese oxide positive electrode material is characterized in that early slow low-temperature sintering is conducted at a rate of less than or equal to 5 ℃ per minute, temperature is increased from normal temperature to 450-700 ℃, heat is preserved for 3-10 hours, atmosphere is air or oxygen, later slow high-temperature sintering is conducted at a rate of less than or equal to 5 ℃ per minute, temperature is increased from normal temperature to 850-1200 ℃, and heat is preserved for 10-20 hours, and atmosphere is air or oxygen.
4. The method for preparing the lithium nickel manganese phosphate coated lithium nickel manganese oxide positive electrode material according to claim 1, wherein a doping element M is further added into the lithium nickel manganese oxide single crystal particles, and the chemical formula of the finally formed lithium nickel manganese oxide is Li x (Ni 0.5 Mn 1.5 ) y M z O 4 , wherein M comprises one or more of Zr, W, mo, Y, ti, nb, al, mg, x is more than 0.9 and less than or equal to 1.1, y is more than 0.985 and less than or equal to 0.999, and z is more than 0.001 and less than or equal to 0.015.
5. The method for preparing a lithium nickel phosphate coated lithium nickel manganese oxide positive electrode material according to claim 1, wherein the doping element M includes W, mo, Y and Ti.
6. The preparation method of the lithium nickel phosphate coated lithium nickel manganese oxide positive electrode material according to claim 1, wherein the lithium nickel manganese oxide precursor is at least one of nickel manganese hydroxide, nickel manganese carbonate and nickel manganese oxide, wherein Ni is 24.5-25.5% by mol% and Mn is 74.5-75.5% by mol%, the lithium source comprises at least one of lithium carbonate, lithium oxide, lithium hydroxide, lithium formate, lithium acetate, lithium oxalate and lithium citrate, and the dopant corresponding to the doping element M is at least one of oxide, hydroxide, carbonate and nitrate of the doping element M.
7. The method for preparing a lithium nickel phosphate coated lithium nickel manganese oxide positive electrode material according to any one of claims 1 to 6, wherein the phosphate solution is a weak acid phosphate aqueous solution, and the phosphate comprises at least one of lithium dihydrogen phosphate and aluminum dihydrogen phosphate.
8. The method for preparing a lithium nickel phosphate coated lithium nickel manganese oxide positive electrode material according to claim 7, wherein the pH of the phosphate solution is=5.5-7.0, preferably pH=5.5-6.0.
9. The method for preparing a lithium nickel phosphate coated lithium nickel manganese oxide positive electrode material according to claim 7, wherein the coating mass wt% of the phosphate is less than or equal to 0.50%.
10. The preparation method of the lithium nickel phosphate coated lithium nickel manganese oxide positive electrode material is characterized in that protective atmosphere for secondary sintering is inert atmosphere, and the secondary sintering is carried out at a rate of less than or equal to 5 ℃ per minute from normal temperature to 500-800 ℃ and preserving heat for 5-20 hours.

Description

Preparation method of nickel lithium phosphate coated nickel lithium manganate positive electrode material Technical Field The invention belongs to the technical field of preparation methods of battery anode materials, and particularly relates to a preparation method of a coated lithium nickel manganese oxide anode material. Background The current state greatly develops new energy industry, and the lithium ion battery anode material has great progress in the aspects of synthesis process, doping modification and the like. The spinel-structured lithium nickel manganese oxide has the advantages of high voltage platform, high specific energy and low cost, but the problem of manganese dissolution cannot be effectively solved. The surface coating technology is to construct a stable protective layer on the surface of the positive electrode material particles to inhibit side reaction of the positive electrode material and an electrolyte interface and dissolution of transition metal. The Chinese patent document No. CN120637424A discloses a positive electrode active material, a positive electrode sheet and a lithium ion battery, wherein the positive electrode active material comprises a core and a coating layer, the coating layer is arranged on the surface of the core, the core comprises lithium nickel manganese oxide, the coating layer comprises lithium nickel phosphate, the particle diameter Dn50 of the core and the thickness d of the coating layer meet that d/(Dn 50) is less than or equal to 1.5 nm/mum and less than or equal to 14 nm/mum, and the positive electrode material can inhibit side reaction of a positive electrode interface and electrolyte while improving the structural stability of the material, and reduce the dissolution of transition metal ions, thereby improving the cycle stability of the lithium ion battery. The preparation method of the inner core disclosed in the patent comprises the following steps of dissolving a first lithium source, a first nickel source and a manganese source in a solvent according to a certain mole ratio, mixing to obtain a mixture, calcining the mixture to obtain the inner core, and forming a coating layer on the surface of the inner core by a physical or chemical coating method according to a certain mole ratio by a second lithium source, a second nickel source, an M source and a phosphorus source. In some embodiments, the physical or chemical coating method comprises at least one of atomic layer deposition, chemical vapor deposition, solid phase sintering, solution combustion. The second nickel source used in this patent includes, but is not limited to, at least one of tetra (dimethylamino) nickel, nickel t-butoxide, tetra (ethylmethylamino) nickel, tetra (ethylamino) nickel, and tetraethoxy nickel. The second lithium source includes, but is not limited to, at least one of lithium t-butoxide, lithium acetoacetate, lithium t-butoxide, and lithium bis (trimethylsilyl) amide. The phosphorus source includes, but is not limited to, at least one of tetramethylene diphosphate, trimethyl phosphate, tris (dimethylamine) phosphorus, or trialkyl phosphorus oxide. M sources include, but are not limited to, t-butoxides of the M element. However, the preparation method of the nickel lithium phosphate coated nickel lithium manganate positive electrode material in the above patent has complex preparation process, uses a large amount of organic nickel salt, organic lithium salt and organic phosphorus source in the preparation of the recoating layer, has difficult preparation and acquisition of the raw materials, has high cost, and needs to be respectively added and then mixed for reaction, so that the problems of uneven element coating, insufficient coating layer reaction, poor coating structure stability and the like easily exist, and further the inhibition effect on the interfacial side reaction of the positive electrode material and electrolyte and the dissolution of transition metal is influenced, and the initial capacity and the later cycle performance of the positive electrode material are also influenced. In addition, the existing coating method has complex technical process, high operation difficulty and higher cost. Disclosure of Invention The invention aims to solve the technical problems and overcome the defects and shortcomings in the background art, and provides a preparation method of a nickel lithium phosphate coated nickel lithium manganate positive electrode material. In order to solve the technical problems, the technical scheme provided by the invention is that the preparation method of the nickel lithium phosphate coated nickel lithium manganate positive electrode material comprises the following steps of uniformly mixing a nickel lithium manganate precursor material and a lithium source material according to stoichiometric ratio, obtaining nickel lithium manganate monocrystal particles through sintering, mixing the nickel lithium manganate monocrystal particles with a