Nanometer lithium-rich manganese-based positive electrode material and precursor, base material and preparation method thereof

Abstract

The invention belongs to the field of lithium ion battery positive electrode materials, and particularly relates to a nanometer lithium-rich manganese-based positive electrode material, and a precursor and a base material thereof. The chemical general formula of the lithium-rich manganese-based positive electrode material precursor is MnxM<1-x>(OH)2, x is more than 0.5 and less than 1, and M is one or two of Ni and Co. Primary particles of the precursor are nanosheets, and the thicknesses of the nanosheets are similar; the crystal faces of the nanosheets face the same direction and are stackedwith one another to form a nanoflower-shaped morphology; the interior is of a radial structure with a core in the center. The lithium-rich manganese-based positive electrode material precursor is calcined to obtain a nanometer lithium-rich manganese-based positive electrode material base material which is provided with oxygen-containing vacancies, with primary particles being nanosheets with thethickness of about 10 nm. According to the present invention, during the lithium mixing sintering of the base material, the primary particles are the ultra-thin nanosheets, such that the specific surface area is large, the contact with a lithium source is complete, the uniform mixing of the base material and the lithium source is easily achieved, the problems of unbalanced reaction and insufficient reaction are avoided, and the performance of the ternary positive electrode material can be easily and completely provided.

Description

technical field [0001] The invention relates to the field of positive electrode materials for lithium ion batteries, in particular to a precursor of a nano lithium-rich manganese-based positive electrode material, an intermediate substrate and a preparation method thereof. Background technique [0002] Lithium-rich manganese-based materials (Li 2 MnO 3 •LiMO  2 ) as a cathode material for lithium-ion batteries, has the advantages of high discharge specific capacity (about twice the discharge specific capacity of cathode materials such as lithium iron phosphate and ternary materials in current commercial applications), safety, reliability, and low price, so it has a wide range of applications. application prospects. However, lithium-rich manganese-based materials still have problems such as poor cycle stability, low rate performance, and low initial efficiency. This is mainly caused by the following reasons: 1. After the first charge, the material Li 2 MnO 3 The extract...

AI Technical Summary

Problems solved by technology

However, lithium-rich manganese-based materials still have problems such as poor cycle stability, low rate performance, and low initial efficiency.

This is mainly caused by the following reasons: 1. After the first charge, the material Li 2 MnO 3 The extraction of lithium ions from the transition metal layer in the phase deteriorates the stability of the crystal structure of the material. After multiple charge-discharge cycles, the lithium-rich manganese-based material will transform from a layered structure to a spinel structure, resulting in a decrease in the cycle stability of the material.

2. When discharging at high voltage, some lithium ions in the transition metal layer of lithium-rich manganese-based materials will be removed together with oxygen to form Li 2 O is released, and it is difficult for this part of the crystal vacancies to accept lithium ions in the subsequent charge and discharge process, resulting in the deterioration of the first charge and discharge efficiency of the material; 3. After the first charge, the oxygen vacancies formed by the oxygen release are thermodynamically unstable. During the discharge process, the interaction between lithium-rich manganese and the electrolyte will also change the crystal structure, thereby reducing the first charge and discharge efficiency and cycle stability.

This method uses a mixture of hydrogen and argon, which is dangerous and expensive

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