Method for preparing flaky single-particle ternary positive electrode material from low-temperature eutectic molten salt

Abstract

The invention relates to the technical field of synthesis of battery positive electrode active materials, in particular to a method for preparing a flaky single-particle ternary positive electrode material from low-temperature eutectic molten salt. The method comprises the following steps: uniformly mixing a precursor with lithium-containing low-temperature eutectic molten salt, and realizing high-temperature liquid-phase sintering in an oxygen atmosphere; crushing and screening the sintered material, and conducting washing with a solvent to remove redundant molten salt, thereby implementing material purification; and drying, crushing and sieving the washed material to obtain the flaky single-particle ternary positive electrode material with excellent crystallinity and a dominant crystal face. The ternary positive electrode material prepared by the method has a single-particle morphology with relatively good dispersity, and the prepared material is high in purity, moderate in particle size and excellent in electrochemical performance; and the whole preparation process is short in time consumption, simple in procedure and easy for industrial control.

Description

technical field [0001] The invention relates to the technical field of synthesis of positive electrode active materials for batteries, in particular to a method for preparing sheet-shaped single-particle ternary positive electrode materials from low-temperature eutectic molten salts. Background technique [0002] Since the 21st century, lithium-ion batteries have been widely used in various fields due to their high specific capacity, long cycle life, and good safety performance, and have become more and more important in people's lives. Compared with the negative electrode, the positive electrode has more limitations and has become a bottleneck restricting the development of lithium-ion batteries. It is urgent to further increase the capacity and reduce the cost. layered oxide LiNi x co y mn z o 2 (NCM) has the comprehensive advantages of high theoretical specific capacity and low cost, and has become a hot research direction of high energy density lithium ion battery ca...

AI Technical Summary

Problems solved by technology

Similarly, single-particle ternary cathode materials also have disadvantages, such as relatively low specific capacity and first Coulombic efficiency at the same cut-off voltage; the particle size is relatively large, generally micron-scale, and the lithium ion intercalation channel distance is long. poor performance

[0004] The existing technology of synthesizing single-particle ternary cathode materials usually adopts a higher synthesis temperature of 850-1000 °C, which will bring a series of problems: such as increased energy consumption and production costs; materials are easy to agglomerate; at high temperatures, Li 2 O is easy to evaporate and lead to lithium deficiency, which requires secondary sintering; the material is easy to decompose at high temperature and Ni 3+ converted to Ni 2+ , the lithium-nickel mixed row increases, and the reversible capacity of the material decreases

Chinese patent 111129485A uses lithium nitrate as a lithium source and flux to synthesize a single-particle ternary positive electrode material with excellent performance, but lithium nitrate has certain safety hazards at high temperatures, and it is easy to decompose to generate nitrogen and oxygen waste gas, which is not conducive to industrial production; China Patent 110534733A prepared large particles with a D50 of 6-12 μm by adding nano-flux, and the sintering temperature was as high as 920-940°C. Excessively large particle sizes lead to poor rate performance and are difficult to apply to high-power batteries

Excessively high sintering temperature and long-term heat preservation will destroy the material structure, cause serious lithium-nickel mixed discharge, and affect the electrochemical performance of the material

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