Electrodeposited Porous Tungsten Oxides as Anode Materials for Lithium Secondary Batteries

Porous tungsten oxide thin films were prepared by electrodeposition and tested as anodes of lithium secondary batteries. The synthesized films were composed of nanoparticles of 60-140 nm size, with porosities of 30-40 %. Increasing the temperature turned out to be a more effective approach to introduce porosity in the structure than increasing the electrolyte viscosity. The assessment of the synthesized films as anodes of lithium secondary batteries revealed a much higher initial discharge capacity for the porous than the dense samples. The discharge capacity retention significantly increased with increasing porosity and was further enhanced by heat treatment. In particular, a thin film composed of particles of about 140 nm in size and with a porosity of 40 % exhibited an initial discharge capacity higher than 600 mAh/g and a remaining capacity above 300 mAh/g after 30 cycles. Following heat treatment, the remaining capacity of this sample after 30 cycles increased to about 500 mA h/g.