Core-shell composite anode material for lithium ion battery and preparation method thereof

Abstract

The invention discloses a core-shell composite anode material for a lithium ion battery. The composite anode material has a core-shell structure; the core-shell structure consists of a core-layer active material and a shell-layer active material; the core-layer active material is LiFePO4 or lithium manganate; the shell-layer active material is carbon-containing LiFePO4; the LiFePO4 has an Li1-XMXFePO4 or LiFe1-yMyPO4 structure; the lithium manganate has a LiMnO2 or LiMn2O4 structure; the carbon is selected from one or more of carbon nano tubes, superfine conductive black and an agraphitic carbon material; and the composite anode material comprises 65 to 99 mass percent of core-layer active material and 1 to 35 mass percent of shell-layer active material. The composite anode material of the invention has stable performance and excellent electrochemical properties; and the lithium ion battery manufactured by using the material has relatively high charge-discharge capacity and excellent cycle performance, can perform quick charging and large multiplying-factor discharging, can adapt to an ultra-low temperature working environment and is safe and stable.

Description

【Technical field】 [0001] The invention relates to a lithium ion battery cathode material, in particular to a composite cathode material for a nanoscale lithium ion battery with a core-shell structure. 【Background technique】 [0002] Green secondary battery is a recyclable, efficient and clean new energy source. Its application can play a comprehensive role in alleviating energy, resource and environmental problems. Especially in recent years, portable electronic products, electric vehicles, aerospace and defense equipment power supply systems based on green batteries, as well as many application fields such as photovoltaic energy storage, energy storage peak-shaving power stations, uninterruptible power supplies, etc., all show Green batteries play a fundamental role in supporting the sustainable development of today's society. As one of the most critical components of lithium-ion batteries, the cathode materials that have been commercially used are mainly lithium transitio...

AI Technical Summary

Problems solved by technology

Its main disadvantage is: poor cycle performance, especially when the temperature is higher than 55 ° C, the capacity decay is very fast, the reason is that the structure of lithium manganate changes during the cycle

The problem is that the structure is unstable after delithiation and slowly transforms to a spinel structure

Since LiFePO 4 The electrochemical process is controlled by diffusion, the ionic conductivity and electronic conductivity are small, and the capacity decays quickly when discharging with a large current.

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