本文以CrO₃为原料,采用高温固相法制备锂电池用正极材料Cr₈O₂₁,系统研究了热处理时间对Cr₈O₂₁结构、电化学性能的影响。采用TGA、XRD、SEM、EDS、ICP、EIS和恒流放电技术对制备的铬氧化物的物相及电化学性能进行研究。结果表明,延长热处理时间有利于提升材料的电化学性能。且不同的热处理时间对材料的电化学性能有重要影响。热处理时间为48 h得到的材料性能优异,在恒放电电流0.05 mA下,材料克比容量达到383.26 mAh·g^-1,克比能量达到1153.83 mWh·g^-1,平均放电电压3.01 V。

Chromium oxide (Cr₈O₂₁) cathode material for lithium batteries was synthesized by thermal decomposition of chromium trioxide (CrO₃) at high temperature. The electrochemical properties of chromium oxide depended on the time and temperature during the heat treatment. Pure phase chromium oxide was prepared, and the effects of heat treatment time on the structures and electrochemical properties of Cr₈O₂₁ were systematically studied. The first discharge mechanism of chromium oxide in lithium batteries was explored, and the results were similar to that in lithium-sulfur batteries. The crystal phases and electrochemical properties of the prepared chromium oxide were analyzed by TGA, XRD, SEM, EDS, ICP, EIS techniques and constant current discharge measurement. The results show that heat treatment time had an important impact. Extending the heat treatment time was beneficial to improve the electrochemical properties of the material. The less the amount of residual CrO₃, the better the electrochemical performance. The severe oxidation reaction between CrO₃ and the electrolyte caused the electrode to be corroded. The material obtained in 48 h exhibited excellent performance, complete crystallization, good morphology, and low electrochemical impedance. At a constant discharge current of 0.05 mA, the specific capacity of the material reached 383.26 mAh·g^-1 with the specific energy of 1153.83 mWh·g^-1 and the average discharge voltage of 3.01 V. This study provides an effective way to prepare pure phase chromium oxide and proves its potential application in the field of lithium batteries.