Positive electrode material and lithium ion battery

Abstract

Embodiments of the invention provide a positive electrode material and a lithium ion battery. The positive electrode material comprises a base material and a coating material formed on at least a partof the surface of the base material. The general formula of the base material is Li<x>Co<y>M<1-y>O<2>, wherein x is no less than 1.0 and no more than 1.2; y is no less than 0.8 and no more than 1.0;M is at least one selected from the group consisting of Mg, Ti, Al, Zr, Ni and Mn; and the coating material comprises Y<2>O<3> and at least two selected from the group consisting of La<2>O<3>, ZrO<2>and CeO<2>. Compared with positive electrode materials that do not contain coating materials or coating materials therein contain only one or two of the above oxides, the positive electrode material provided in the embodiments of the invention allows a battery core prepared from the positive electrode material to have a low storage expansion ratio and a high capacity retention rate through the co-action of at least three oxides and improves cycle performance at a high charging cut-off voltage.

Description

technical field [0001] The embodiments of the present application relate to the field of batteries, and more specifically, to positive electrode materials and lithium ion batteries. Background technique [0002] Lithium cobalt oxide (LiCoO 2 , abbreviated as LCO) mainly, LiCoO 2 The electrochemical performance of the material is relatively stable, the cycle performance is good, the voltage platform is high, and the compatibility with the electrolyte is good, but at a lower voltage, LiCoO 2 The gram capacity of the battery is low, such as 140mAh / g, and its exertion is low. When the charging voltage increases, such as 4.45-4.6V, the delithiation capacity can reach more than 75%. LiCoO due to excessive delithiation 2 An irreversible transformation of the crystal structure occurs inside, resulting in the degradation of gram capacity and cycle performance. In addition, due to the high voltage LiCoO 2 The increase in the release of Co elements in the cathode material leads to...

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Problems solved by technology

[0002] Lithium cobalt oxide (LiCoO 2 , abbreviated as LCO) mainly, LiCoO 2 The electrochemical performance of the material is relatively stable, the cycle performance is good, the voltage platform is high, and the compatibility with the electrolyte is good, but at a lower voltage, LiCoO 2 The gram capacity is low, such as 140mAh / g, and its exertion is low. When the charging voltage increases, such as 4.45-4.6V, the delithiation capacity can reach more than 75%

LiCoO due to excessive delithiation 2 Irreversible transformation of crystal structure occurs inside, leading to degradation of gram capacity and cycle performance

In addition, due to the high voltage LiCoO 2 The increase in the release of Co elements in the cathode material leads to the release of oxygen in the crystal structure, LiCoO 2 The oxygen released in the battery reacts with the electrolyte to produce a large amount of gas, which will deteriorate the storage performance of the battery cell, thereby further deteriorating the overall performance of the battery cell.

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