Electro-spun Co^sub 3^O^sub 4^ anode material for Na-ion rechargeable batteries

Cobalt oxide fibres are synthesised via electro-spinning followed by calcination in air at 600 °C. Texture, morphology and surface composition of the fibres, as well as phase of the oxide formed are investigated by means of a combination of characterisation techniques. The electrochemical performance of the electro-spun Co3O4 fibres as anode material in Na-ion rechargeable batteries is evaluated, and the conversion reaction mechanism is investigated by carrying out ex-situ analyses on the cycled electrodes. The formation of the CoO after the first sodiation/desodiation cycle accounts for the cathodic specific capacity lowering from 983 down to 580 mAh g- 1. The high aspect ratio morphology of the fibres is responsible for the high value of initial cathodic specific capacity and the slow capacity fading (after 30 cycles, a cathodic capacity of 407 mAh g- 1 is retained).