关键词: 氧化铬, 正极材料, 锂电池

Abstract:

Chromium oxide with high capacity, high voltage, and low cost has drawn much attention as a cathode material for lithium batteries. This study prepares high pure-phase Cr₈O₂₁ through one-step pyrolysis under oxygen atmosphere with CrO₃ as precursor. The chemical composition, morphology, and corresponding electrochemical performance of the samples prepared at different pyrolysis conditions are analyzed through X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, and electrochemical techniques. The results show that the pyrolysis temperature greatly affects the electrochemical performance of chromium oxides. The insufficient decomposition of CrO₃ at lower temperatures results in electrode damage, and the impurity phase of Cr₂O₅ formed during pyrolysis under higher temperatures significantly reduces the specific capacity. Cr₈O₂₁ prepared at 270 ℃ for 24 h exhibits an outstanding performance with a high specific capacity of 357 mAh/g at first discharge under 0.1 C and an average voltage reaching 3 V. The capacity retention exceeds 80% after a 20-cylce test. In addition, high specific capacities of 200 and 363 mAh/g are achieved at -45 ℃ and 65 ℃, respectively, indicating the excellent cycling stability and electroactivity of Cr₈O₂₁.

Key words: chromium oxides, cathode materials, lithium battery