High performance NaxCoO2 as a cathode material for rechargeable sodium batteries

Sodium cobalt oxide (NCO) has been synthesized by a glycine assisted sol-gel combustion method. XRD studies confirm the P2 phase formation of NCO. Na exists in two different environments in the NCO crystallite structure, which is confirmed by Na-23 Nuclear Magnetic Resonance spectra (NMR). Morphological studies confirm that the particles are unique with a stacked hexagonal shape. Galvanostatic charge/discharge studies performed at different current rates (0.1, 0.2 and 0.5) deliver reversible specific capacities of 126, 108 and 77 mA h g(-1) respectively. Further, cycle life performance of the fabricated cells after 50 cycles at 0.1 C rate exhibits an average discharge capacity of similar to 121 mA h g(-1) with a capacity retention of similar to 86% (Coulombic efficiency similar to 99.9%). The investigated NCO's superior performance suggests its suitability as a cathode material for Na-ion batteries.