T2 type lithium cobalt oxide positive electrode material with space group of Cmca and preparation method of T2 type lithium cobalt oxide positive electrode material

Abstract

The invention discloses a T2 type lithium cobalt oxide positive electrode material with a space group of Cmca and a preparation method of the T2 type lithium cobalt oxide positive electrode material. The chemical formula of the material is LixNayCoO2, x is more than or equal to 0.6 and less than or equal to 1, and y is more than or equal to 0 and less than or equal to The lithium ions and the adjacent oxygen ions form tetrahedral coordination; the main peak of an X-ray diffraction pattern is 17.9-18.1 degrees, and the crystal face diffraction peak of 131 is strong within 67.0-67.5 degrees, and belongs to the characteristic peak of a Cmca space group. The preparation method comprises the following steps: synthesizing a precursor P2-phase layered sodium cobalt oxide by a solid-phase ball milling method or a coprecipitation method, and then carrying out ion exchange to obtain the T2-configuration lithium cobalt oxide layered positive electrode material. The synthesized positive electrode material product is uniform in particle and high in crystallinity; the first coulombic efficiency is 125%; the cycle performance and the rate performance are very excellent, and the reversible capacity under the rate of 135 mA / g reaches up to 230 mAh / g; the specific capacity is also greatly improved compared with that of a mainstream commercial positive electrode material in the market; the synthesis method is simple and easy to implement, and industrial large-scale production is facilitated.

Description

technical field [0001] The invention belongs to the field of lithium ion battery materials and electrochemistry, in particular to a T2-type lithium cobalt oxide layered positive electrode material prepared by an ion exchange method with a space group of Cmca. Background technique [0002] Lithium-ion battery is a kind of secondary battery with repeatable charge and discharge characteristics. It has been developed for many years. Its application involves many fields such as transportation, entertainment, military, medical treatment and communication. The lithium-ion battery developed in recent years Electric vehicles have high application prospects due to their environmental friendliness. However, due to the limitation of battery specific energy density, electric vehicles cannot meet the needs of most users, so they have not been widely used. At present, the main factor limiting the specific energy density of the battery is the cathode material, and there are several mainstr...

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Problems solved by technology

However, the limitation of battery specific energy density makes electric vehicles unable to meet the needs of most users, so they have not been widely used.

At present, the main factor limiting the specific energy density of batteries is the cathode material. Several mainstream materials on the market O3-LiCoO 2 (140 mAh / g), LiFePO 4 (160 mAh / g), LiMn 2 o 4 (150 mAh / g) The specific capacity is lower than 200 mAh / g, which can meet the high capacity requirements of the lithium-rich manganese-based cathode xLi 2 MnO 3 ·(1-x)LiMO 2 (250 mAh / g) The problem of voltage decline has not been solved well for a long time, so finding a lithium battery cathode material with high energy density and stable structure is a major task in the current lithium battery research field

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