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

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 509mAh/g at 100mA/g and good rate capability. Nevertheless, the discharge capacity decreased to 337mAh/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 480mAh/g was retrained after 50 cycles when the electrolyte with 0.02M Na₂S₂O₃ addition was employed, yielding an excellent cycling performance.