Hierarchical NaxCoO2 microspheres with low surface area toward high performance sodium ion batteries

Abstract

Traditional NaxCoO2 (0 < x ≤ 1) generally suffers from severe capacity fading in terms of complicated phase transitions. On account of this, we synthesize P2-type NaxCoO2 microspheres (s-NCO) by the novel sodiation and calcination strategy. This s-NCO specimen occupies low surface area (~2.82 m2 g−1) and hierarchical construction. Owing to this unique microsphere architecture, s-NCO electrode materials show competitive electrochemical performance. The s-NCO electrode demonstrates excellent electrochemical stability with the specific capacity of 82.2 mAh g−1 undergoing 300 cycles at the current rate of 6 C.