Effect of Annealing Treatment on the Electrochemical Properties of Polyoxomolybdate K₄[SiMo₁₂O₄₀] as Cathode Material of Lithium Battery

Abstract

Silicon-centered polyoxomolybdate K₄[SiMo₁₂O₄₀] (KSM) with the Keggin type structure was investigated as the cathode material for rechargeable lithium battery. The discharge capacity and cycle performance of KSM mainly depends on the annealing temperature. This material shows improved discharge capacity by the increase of annealing temperature. Rietveld analysis of X-ray powder diffraction data and Raman spectra were used to analyze the effect of annealing treatment on the cycle performance of KSM. The results indicate that the improvement of cycle performance would be caused by the re-oxidation of Mo⁵⁺ ion in KSM reduced during the preparation process. The KSM cathode shows better electrochemical performance than that of the reported phosphorous-centered polyoxomolybdate K₃[PMo₁₂O₄₀] (KPM), indicating that KSM as the cathode material with high discharge capacity and cycle stability is accessible.