Improved electrochemical properties of flower-like Co hierarchitectures as anode materials for alkaline secondary batteries

Abstract

Co-based anode materials are regarded as high capacity anode for alkaline secondary batteries. Their application, however, is limited by poor cycling stability. Herein, flower-like Co hierarchitectures with hcp crystal structure were synthesized by a simple chemical reduction method. The as-prepared Co electrode shows a high maximum discharge capacity of 509[Formula: see text]mAh/g at 100[Formula: see text]mA/g and good rate capability. Nevertheless, the discharge capacity decreased to 337[Formula: see text]mAh/g after 50 cycles due to dissolution of the Co electrode into the electrolyte. The addition of Na2S2O3 in the electrolyte can restrain this dissolution and contributes to significant improvement in the cycling stability. A high reversible discharge capacity of 480[Formula: see text]mAh/g was retrained after 50 cycles when the electrolyte with 0.02[Formula: see text]M Na2S2O3 addition was employed, yielding an excellent cycling performance.