Improving the performance of lithium-sulfur batteries using conductive polymer and micrometric sulfur powder

In this study, a conductive polymer, poly(3,4-ethylenedioxythiophene) or PEDOT, was used as binder in the sulfur electrode to study electrochemical performance of lithium-sulfur (Li-S) batteries. PEDOT-based sulfur electrode was compared with that of polyvinylidene difluoride binder based sulfur electrode. Different particle size sulfur materials including commercial micrometric sulfur particles and synthesized colloidal nanometric sulfur powders were chosen as active materials to study the impact of particle size on the cell performance. Different electrolytes including lithium bis(trifluoromethanesulfonyl)imide in polyethylene glycol dimethyl ether (PEGDME) or 1,3-dioxolane-dimethoxy ethane were used in the Li-S batteries to investigate the impact of electrolyte on cell performance. The PEDOT and micrometric sulfur based electrode with PEGDME electrolyte had the best cycle performance, which showed a capacity retention of 68% and specific capacity of 578 mAh/g after 100 cycles. The increased conductivity by conductive polymer and the high viscosity of PEGDME play important roles in the improvement of cycle performance.