Cobalt Hexacyanoferrate as Cathode Material for Na+ Secondary Battery

We investigated structural and electrochemical properties of thin film electrodes of cobalt hexacyanoferrate, NaxCo[Fe(CN)(6)](0.90)2.9H(2)O, against x. The compound exhibits a high capacity of 135 mAh/g and an average operating voltage of 3.6V against Na, with a good cyclability. The discharge curve exhibits two plateaus at approximate to 3.8 and approximate to 3.4 V, which are ascribed to the reduction processes of Fe3+ and Co3+, respectively. The ex situ X-ray diffraction (XRD) profiles reveal the robust nature of the host framework against Na+ intercalation/deintercalation. Thus, cobalt hexacyanoferrate is a promising candidate for the cathode material of sodium-ion secondary battery (SIB). (C) 2013 The Japan Society of Applied Physics