A modified cobalt-free lithium-rich cathode material, its preparation method and application

Abstract

The invention provides a modified cobalt-free lithium-rich positive electrode material, a preparation method and application thereof, the modified cobalt-free lithium-rich positive electrode material comprises an inner core and a lithium metal oxide layer wrapping the inner core, and the inner core is doped Cobalt-free lithium-rich cathode particles for metal ions. The invention utilizes metal ion doping and surface coating to effectively improve the interlayer spacing of the cobalt-free lithium-rich positive electrode material and fix the dissolution of manganese ions, thereby increasing the number of active sites where lithium ions are embedded in the positive electrode material during the first discharge process , thereby improving the first effect; on the other hand, the lithium metal oxide layer has a three-dimensional lithium ion channel, which can effectively slow down Li 2 MnO 3 In the phase transition process, the participation of metal ions can play a pinning effect and stabilize the structure of the material, thereby reducing the problem of voltage decay during cycling of cobalt-free lithium-rich cathode materials.

Description

technical field [0001] The invention belongs to the technical field of lithium batteries, and relates to a modified cobalt-free lithium-rich positive electrode material, a preparation method and application thereof. Background technique [0002] Nowadays, facing the problems of environmental pollution and climate warming caused by the over-exploitation of global fossil energy, people urgently need to replace non-renewable fossil energy with renewable energy. Although renewable energy has no possibility of energy exhaustion, it is affected by natural conditions. The most important thing is the low utilization rate, which is difficult to store and use on a large scale. Lithium batteries have become the most ideal energy storage medium due to their high energy density and high power density. As we all know, lithium batteries are mainly composed of positive electrodes, separators, organic electrolysis It is composed of four parts: liquid and negative electrode. The positive elec...

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Problems solved by technology

[0002] Today, in the face of environmental pollution and climate warming caused by the over-exploitation of global fossil energy, people urgently need to replace non-renewable fossil energy with renewable energy. Although renewable energy does not have the possibility of energy depletion, it is affected by natural conditions. Large, the most important thing is that the utilization rate is low, and it is difficult to store and use on a large scale. Lithium batteries have become the most ideal energy storage medium because of their high energy density and high power density. As we all know, lithium batteries are mainly composed of positive electrodes, separators, organic electrolysis Liquid and negative electrode are composed of four parts, among which the positive electrode material plays a very important role in determining the performance and cost of the battery. Traditional lithium battery positive electrode materials include spinel positive electrode materials, layered structure positive electrode materials, olivine structure positive electrode materials, etc. , but the above traditional positive electrode materials cannot meet the needs of lithium-ion batteries in electric vehicles and other related fields due to their low capacity. In addition, the prices of cobalt and nickel have continued to rise in recent years, resulting in the current price of ternary materials. Lithium-rich Compared with other traditional cathode materials, manganese-based layered oxide cathode materials have the advantages of high capacity, high theoretical energy density and low price. However, there are also problems such as poor cycle performance and voltage drop, which prevent their further industrialization.

[0003] Cobalt-free lithium-rich cathode materials generally have the problem of low first effect and voltage decay after cycling. In the existing technology, the cobalt-free lithium-rich materials are mainly doped and coated, but the effect improvement is not too obvious

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