Single-crystal nickel cobalt lithium manganate positive electrode material and preparation method and application thereof

Abstract

The invention discloses a single-crystal nickel cobalt lithium manganate positive electrode material and a preparation method and application thereof. The positive electrode material is of a core-shell structure, and the material of a core layer is a high-nickel nickel cobalt manganese ternary single-crystal positive electrode material; the material of the shell layer comprises Lir(NisCotMn1-s-t)O2 (II), metal oxide and metal metaphosphate, in the formula (II), 0.9< / =r< / =1.05, 0.3< / =s< / =0.5, 0<t<0.4, and 1-s-t>0; in terms of mass percentage, in the material of the shell layer, the formula (II) accounts for more than 50% by mass, and the feeding mass ratio of the metal oxide to the metal metaphosphate is 1: (0.1-10). The preparation method comprises the following steps of mixing, dispersing and grinding a precursor of a formula (II), a metal oxide and metal metaphosphate, mixing and sintering with a lithium source to obtain a shell layer material, mixing with a core layer material, and sintering to obtain the positive electrode material. The positive electrode material can be suitable for working under 4.5 V high voltage and has ideal cycle stability.

Description

technical field [0001] The invention belongs to the field of lithium ion battery electrode materials, in particular to a positive electrode material, in particular to a single crystal nickel-cobalt lithium manganese oxide positive electrode material and a preparation method and application thereof. Background technique [0002] Nowadays, with the continuous improvement of lithium-ion battery capacity requirements for pure electric vehicles, hybrid vehicles and portable energy storage devices, people expect to develop lithium-ion batteries with higher energy density and power density to achieve long-term battery life and energy storage. Increasing the working voltage of the battery is one of the effective ways to increase the energy density of the lithium-ion battery. However, increasing the working voltage will cause a series of problems such as the degradation of the cycle performance of the lithium-ion battery, such as the increase of side reactions at the electrode / electro...

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Problems solved by technology

[0002] Nowadays, with the continuous improvement of lithium-ion battery capacity requirements for pure electric vehicles, hybrid vehicles and portable energy storage devices, people expect to develop lithium-ion batteries with higher energy density and power density to achieve long-term battery life and energy storage. Increasing the working voltage of the battery is one of the effective ways to increase the energy density of the lithium-ion battery. However, increasing the working voltage will cause a series of problems such as the degradation of the cycle performance of the lithium-ion battery, such as the increase of side reactions at the electrode / electrolyte interface and the increase of oxygen The precipitation increases the polarization and internal resistance of the battery, leading to the problem of poor cycle life

In order to improve the thermal stability and cycle performance of ternary materials under high voltage, common methods include coating and modifying ternary cathode materials. However, although the current ternary materials have been coated and modified, they still cannot perform well Coated on the surface of the positive electrode material, and cannot effectively reduce the reaction of the electrolyte / material interface under high voltage, the cycle stability is poor, and it is difficult to meet the actual needs

At the same time, the traditional secondary spherical particle structure is poor in firmness, and its skeleton structure is easily damaged under higher voltage, which leads to aggravated electrode / solution interface reaction, resulting in a decrease in battery performance.

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