Se as Eutectic Accelerator SPAN Cathode for K-S Batteries with Improved Specific Capacity and Reaction Kinetics

Potassium-sulfur (K-S) batteries are regarded as the most promising energy storage applications due to its excellent specific capacity, widespread resources and low-cost of potassium and sulfur. As a cathode material, the unique solid-solid reaction mechanism of sulfurized poly(acrylonitrile) (SPAN) effectively restrains the shuttle effect and closes to 100 % for coulombic efficiency. However, the application of SPAN is still limited by its sluggish kinetics and inferior cycle performance. Herein, a SPAN with Se as eutectic accelerator (Se-SPAN) was synthesized via vacuum melting and sulfurization treatments, Se not only enhances the reaction kinetics of S but also improves utilization rate of S. Compared to SPAN, the Se-SPAN shows outstanding capacity of 1551 mAh g-1 at 0.1 C and 1311.3 mAh g-1 at 0.5 C. In addition, a superior cycle stability is acquired with a capacity retention of 87.4 % at 0.5 C for 100 cycles. Therefore, this work provides a strategy to design high performance electrode materials for K-S batteries. Herein, a SPAN with Se as eutectic accelerator (Se-SPAN) was synthesized via vacuum melting and sulfurization treatments. The Se-SPAN exhibits a higher initial capacity of 1294 mAh g-1 at 0.5 C and superior cycle staCompared to SPAN,bility, the capacity retention reaches up to 87.4 % at 0.5 C for 100 cycles, demonstrating Se can clearly improve the cycle performance and capacity of SPAN.+image