Modified spinel lithium manganate for secondary lithium ion battery and preparation method thereof

Abstract

The invention is modification of spinel lithium manganate for secondary lithium ion batteries and its preparation method, and is characterized in that the spinel lithium manganate is orderly coated with a silica film and an outer carbon film, which forms a composite material with a spinel lithium manganate-silica-carbon three-layer core-shell structure. The coating is performed by a sol-gel method and a solid phase coating method respectively. The composite material with the three-layer core-shell structure has excellent rate capability, and has a 5C / 0.2C discharge capacity ratio of up to 86%. The normal-temperature and high-temperature cycle performance are greatly improved; the capacity retention rate for 100 cycles of normal-temperature 1C is up to 98%; the capacity retention rate for 100 cycles of 55 DEG C 1C is up to 94%, such as a modified spinel lithium manganate material coated with Li1.04Al0.05Mn1.95O4 body-5 wt% silica coating-5 wt% carbon coating. The problems of unstable cycle performance and poor rate capability of the spinel lithium manganate for secondary lithium ion batteries are effectively solved. The preparation method of the invention is simple and practical, low in cost, and is applicable to large-scale production.

Description

technical field [0001] The invention is an improvement to the modified spinel lithium manganese acid for secondary lithium ion batteries and its preparation method, in particular to a modified spinel manganese acid for secondary lithium ion batteries with stable cycle performance and excellent rate characteristics lithium. Background technique [0002] As a new generation of green secondary batteries, lithium-ion batteries have the advantages of small size, light weight, large capacity, small self-discharge, long cycle life, and no memory effect. The application has attracted more and more attention, especially as a power source to replace traditional petrochemical Energy is even more concerned. [0003] The performance of lithium-ion power batteries largely depends on the positive electrode material. Among the developed positive electrode materials, lithium manganese oxide with spinel structure and lithium iron phosphate with olivine structure have good rate charge and dis...

AI Technical Summary

Problems solved by technology

However, since the metal oxide is coated on the surface of spinel lithium manganese oxide in granular form, the coating layer is discontinuous, the film-forming property is poor, and the coating thickness is difficult to control, so it is actually impossible to effectively inhibit the dissolution of manganese, especially The cycle performance of modified spinel lithium manganese oxide is still poor under the condition of high temperature charge and discharge

In addition, metal compounds are electronic insulators, and the prepared electrode materials have poor rate characteristics.

[0007] The above prior art shows that although various efforts have been made to modify LiMn2O4, the The actual effect achieved is limited, and the above shortcomings still have room for improvement

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