Nano-Al as a promising cathode additive for lithium-sulfur batteries

Acetylene black-based sulfur electrodes with different amount (up to 5 wt%) of nano-Al additive were fabricated and the influence of the additive contents on the electrochemical properties were investigated. Due to much improved electrical conductivity in the modified cathode materials, better reaction kinetics was demonstrated in comparison with the conventional sulfur electrode. Overall, the electrochemical performances significantly increased between 0 and 1.25 wt% of the nano-Al additive, then decreased successively between 1.25 and about 5 wt%. Maximal electrochemical activity was observed for about 1.25 wt%, and the resultant revealed highest rate capacity and cyclic stability. Specifically, the prepared electrode can deliver a high initial discharge capacity of 978 mAh g(-1) and remain a reversible capacity of 696 mAh g(-1) after 300 cycles at a charge-discharge rate of 0.2C. With nano-Al content higher than 1.25 wt%, the electrochemical performances tend to be negatively affected due to the reduction in sulfur-carbon interfaces and more obstruction in Li+ ion migration and diffusion.