Lithium cobalt oxide positive electrode material, preparation method thereof and lithium battery

Abstract

The invention provides a lithium cobalt oxide positive electrode material and a preparation method thereof, the preparation method is characterized in that three elements Ba, Ga and Ru with different modification action mechanisms are doped into a lithium cobalt oxide lattice, and the barium element realizes the purpose of reducing a Li < + > diffusion energy barrier by adjusting a geometric structure and an electronic structure of lithium cobalt oxide; the gallium element plays a role in stabilizing the lattice structure of the lithium cobalt oxide through high binding energy with oxygen; the ruthenium element plays a role in inhibiting charge compensation behavior of oxygen in lithium cobalt oxide under high voltage and irreversible phase change under 4.55 V by reducing an energy level overlapping region of a 3d track of cobalt and a 2p track of oxygen, and under the action of three different regulation mechanisms, the capacity, the cycling stability and the rate capability of the lithium cobalt oxide positive electrode material under high voltage are improved, and meanwhile, the lithium cobalt oxide positive electrode material has wider practical applicability in the aspect of electrochemical energy storage due to the good electrochemical charge-discharge behavior of the lithium cobalt oxide positive electrode material.

Description

【Technical field】 [0001] The invention relates to the technical field of lithium batteries, in particular to a lithium cobalt oxide cathode material, a preparation method thereof, and a lithium battery. 【Background technique】 [0002] Lithium-ion batteries using lithium cobaltate as the positive electrode material have always occupied a dominant position in the battery market due to their high energy density, large compaction density, stable charge and discharge voltage, and high operating voltage. However, the ideal cathode material for lithium-ion batteries should be Li + and e - The mixed conductor has balanced electronic conductivity and ionic conductivity, but in lithium cobaltate cathode material, electronic conductivity (10 -3 .S cm -1 ) is much higher than the ionic conductivity (10 -8 .S cm -1 ), such a low ionic conductivity will not only make Li + The transport in the bulk phase of the lithium cobalt oxide cathode material is slow, and in the cathode - A la...

AI Technical Summary

Problems solved by technology

However, the ideal cathode material for lithium-ion batteries should be Li + and e - The mixed conductor has balanced electronic conductivity and ionic conductivity, but in lithium cobaltate cathode material, electronic conductivity (10 -3 .S cm -1 ) is much higher than the ionic conductivity (10 -8 .S cm -1 ), such a low ionic conductivity will not only make Li + The transport in the bulk phase of the lithium cobalt oxide cathode material is slow, and in the cathode - Larger polarization will occur at the interface of the electrolyte, thus limiting the lithium cobalt oxide cathode material to exert a higher capacity

In addition, when working at a high cut-off voltage, the lattice of lithium cobalt oxide undergoes drastic changes, and an irreversible phase transition from the hexagonal phase to the monoclinic phase occurs due to the loss of oxygen, and the structure of the monoclinic phase is extremely unstable, which will lead to cobalt Rapid Decay of Electrochemical Performance of Lithium Acid Batteries

In order to solve the problem of poor cycle performance and rate performance of lithium cobalt oxide materials under high cut-off voltage, improve the ionic conductivity of lithium cobalt oxide cathode materials

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