Effect of surface coating on the electrochemical performance of cathode made of sulfur–loaded TiO2 nanotube arrays

Highlights: • S was confined by TiO₂ nanotube and coating layer to prevent the shuttle phenomenon. • S insertion was applied by using the incipient wetness impregnation method. • Formation of coating layer was applied by using the brush. • The TiO₂ nanotube was used as a conductor, reservoir and support. • This study is to improve the cycling performance for S cathode. Amorphous phase TiO₂ nanotube (NT) arrays as sulfur reservoir are fabricated by anodization method on Ti plate used as current collector. Properties of the NT arrays before heat-treatment are evaluated with those after heat-treatment for applicability as a reservoir and conductor of sulfur electrode. A reasonably high amount of sulfur is loaded (14.8%) from 30% feed sulfur solution at 160 °C in the candidate NT array chosen as the sulfur reservoir. Three electrodes from the only NT array, the sulfur-loaded NT array with and without coating layer are evaluated on electrochemical performances. The sulfur electrode with coating layer, consisting of super-P and PVdF, exhibits the highest initial and retention capacity in discharge, respectively, of 1547 mAh g⁻¹ and 1085 mAh g⁻¹ up to 100 cycles. Rate capability at various C-rates from 0.1 to 30 C is also found to be exceptionally good.