A kind of lithium titanate negative electrode material and preparation method thereof

Abstract

The invention belongs to the field of energy storage material research, and particularly relates to a lithium titanate negative electrode material. The particle diameter of the lithium titanate negative electrode material is D1, the lithium titanate negative electrode material comprises a core structure, a first coating layer, a second coating layer until an n(th) coating layer and a low (n+1) coating layer, wherein n is more than or equal to 2; in the core structure, the first coating layer, the second coating layer until the n(th) coating layer and the low (n+1) coating layer, the contents of lithium titanate constituents respectively account for x<0>%, x<1>% until x<n>% and x<n+1>%, 1>=x<0>%>=x<1>% until >=x<n>%>=x<n+1>%; and in the core structure, the first coating layer, the second coating layer until the n(th) coating layer and the low (n+1) coating layer, the contents of auxiliary constituents respectively account for y<0>%, y<1>% until y<n>% and y<n+1>%, y<0>%<=y<1>% until <=y<n>%, and n is more than or equal to 2. In the structure, the auxiliary constituents with higher capacity and more stable performance are arranged on surface layers of particles, the lithium titanate constituent which is high in rate and is easy to generate negative reaction after being in contact with an electrolyte is arranged in the particles, and thus, the special functions (such as high capacity and high stability) of an auxiliary material and the high-rate characteristic of the lithium titanate negative electrode material can be simultaneously developed.

Description

technical field [0001] The invention belongs to the technical field of energy storage materials, and in particular relates to a lithium titanate negative electrode material and a preparation method thereof. Background technique [0002] Lithium-ion batteries have brought revolutionary changes to the field of energy storage since their birth due to their advantages such as fast charging and discharging, good low-temperature performance, large specific energy, small self-discharge rate, small size, and light weight. Used in various portable electronic devices and electric vehicles. However, with the improvement of people's living standards, higher user experience puts forward higher requirements for lithium-ion batteries: faster charging and discharging (such as 5C or even 10C), wider temperature range (such as minus 30 degrees Celsius) Use, etc.; In order to solve the above problems, it is necessary to find new electrode materials with more excellent performance. [0003] A...

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Problems solved by technology

[0004] However, due to the poor electrical conductivity of the lithium titanate material particles, the internal resistance of the battery after assembly is large, and the gas is easy to be generated during the charging and discharging process, which affects the use of the battery, limiting its wider application.

In order to solve the above problems, the existing technologies mainly include nanonization of lithium titanate particles, or coating on the surface of lithium titanate negative electrode materials. While stabilizing the structure of the material, it can also prevent direct contact between the lithium titanate material and the electrolyte and avoid The battery produces a large amount of gas during the cycle; thus, while improving the cycle performance of the battery, it solves the problem of gas production in the lithium titanate battery; at the same time, the lithium titanate material itself has a low gram capacity, and the voltage platform when it is used as a counter electrode with metal lithium Higher, when used as a negative electrode material, it will lower the voltage of the full battery, resulting in low energy density of the full battery; the above problems limit its wider application

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