High-Performance Sulfurized Polyacrylonitrile Cathode by Using MXene as a Conductive and Catalytic Binder for Room-Temperature Na/S Batteries.

Sulfurized polyacrylonitrile (PAN@S) is a promising cathode material for room-temperature Na/S batteries but suffers from low conductivity and insufficient electrochemical activity, resulting in unsatisfactory actual capacity and rate performance. Herein, Ti 3 C 2 T x MXene nanosheets are used as a conductive and catalytic binder to establish the PAN@S electrode, wherein MXene constructs a highly conductive framework for fast charge transport and provides high catalytic effect to improve the active material utilization and accelerate the redox kinetics significantly. Therefore, the PAN@S electrode bonded by MXene shows an electronic conductivity of 5.05 S cm -1 , 4 orders of magnitude higher than the conventional electrodes bonded by the insulative polymer binders, and much decreased activation energy barrier and resistance. Consequently, the PAN@S electrode displays superior performance in terms of high capacity (697.3 mAh g -1 at 200 mA g -1 ), unparalleled rate capability (189.0 mAh g -1 at 20 A g -1 ), and excellent high-rate cycling performance (a capacity decay rate of ∼0.04% per cycle during 1000 cycles at 5 A g -1 ). This work provides a high-performance electrode for room-temperature Na/S batteries and shows the promising potential of conductive and catalytic MXene binders in boosting the performance of active materials.