P3-type K0.33Co0.53Mn0.47O2·0.39H2O: a novel bifunctional electrode for Na-ion batteries

Abstract

A novel electrode material, P3-type K_0.33Co_0.53Mn_0.47O₂·0.39H₂O (KCM), is synthesized through an easily-operated sol–gel method and it delivers considerable Na ion storage abilities when employed as both a cathode and an anode in NIBs. As a cathode, the compound displays remarkable average voltage potentials (over 3 V) and a high discharge capacity (114 mA h g⁻¹ at 100 mA g⁻¹). As an anode, a safe and ideal average voltage potential (0.53 V), a high discharge capacity (174 mA h g⁻¹), and a long cycle life (950 cycles at 500 mA g⁻¹) are also delivered together. In addition, a KCM-based full cell is subsequently built and even without any optimization it can still exhibit a high energy density (91 W h kg⁻¹) accompanied by a long cycle performance (100 cycles at 100 mA g⁻¹).