Synthesis process and modification technology of lithium manganese oxide

1、Synthesis process

At present, there are six preparation methods of lithium manganate, including high-temperature solid phase method,

 melt impregnation method, microwave synthesis method, hydrothermal synthesis method, coprecipitation method, and sol gel method.

Among them, there are currently two main types of lithium manganese oxide on the market: 

AB type, A type refers to materials used for power batteries, and its characteristics mainly consider safety and recycling. 

Class B refers to substitutes for mobile phone batteries, mainly characterized by high capacity.

① High-temperature solid-phase method

The basic process flow of high-temperature solid-phase method is: mixing → roasting → grinding → screening → product. 

The solid-phase method has the advantages of simple operation process, large-scale production, and low cost.

② Melt impregnation method

The melt impregnation method refers to a better method for preparing spinel lithium manganese oxide by solid-phase method. 

It is possible to obtain negative electrode materials with excellent electrochemical performance, but due to complex operation and harsh conditions, it is not conducive to industrialization.

③ Microwave synthesis method

The microwave synthesis method is significantly different from the traditional high-temperature solid-phase method in the synthesis of materials. 

By using this method, materials with excellent electrochemical performance can be prepared, and the synthesis reaction time can be greatly shortened.

④Hydrothermal synthesis method

The lithium ion battery cathode material LiMn2O4 synthesized by hydrothermal synthesis method has a stable crystal structure and uniform crystalline state, 

thus the synthesized material has excellent physical and electrochemical properties.

⑤ Co precipitation method

The lithium-ion battery materials prepared by co precipitation method not only have higher electrochemical capacity and longer cycle life, 

but also have the advantages of simple process, convenient operation, and fast reaction speed.

⑥Sol gel method

Sol gel method is actually a branch of coprecipitation method. 

The produced LiMn2O4 has excellent physical and electrochemical properties, but due to high costs, it is not conducive to industrial production.

2、Modification technology

As a widely used positive electrode material for lithium batteries,

 the main limiting factor for the development of spinel lithium manganese oxide is the capacity degradation during charge and discharge. 

Surface modification and doping can effectively improve its electrochemical performance.

By surface modification, the electrode surface can be surrounded by a substance that is resistant to electrolyte erosion, 

which can effectively suppress the decomposition of electrolyte and the dissolution of manganese. 

Doping can effectively improve the stability of spinel lithium manganese oxide structure and suppress the occurrence of Jahn Teller effect.

The combination of doping and surface modification can further improve the electrochemical performance of materials, 

which is a major direction for future research on the modification of spinel lithium manganese oxide batteries.

① Surface modification methods

The surface modification method mainly involves coating the surface of the electrode with a substance that can resist electrolyte erosion,

 forming a protective film that only allows Li+to pass through, and electrolyte solution and H+cannot pass through. 

This reduces the specific surface area of the material and slows down the corrosion rate of hydrofluoric acid,

 thereby suppressing the dissolution of manganese and the decomposition of the electrolyte.

② Doping modification

Body doping is an effective method to improve the electrochemical performance of lithium manganese oxide cathode materials from within the lattice. 

When an appropriate amount of impurity ions are doped into the cathode material,

 the Jahn Teller effect can be effectively suppressed during charge and discharge, thereby improving its structural stability, hindering its structural changes, and reducing manganese dissolution. 

The main methods of doping include anion doping, cation doping, and composite doping of anions and cations.