High-Performance Stable Potassium–Sulfur Batteries Enabled by Free-Standing CNT Film-Based Composite Cathodes

To maintain the tendency towards lower cost and sustainability of innovative battery technologies, one challenge is the development of high-energy ecofriendly devices based on the potassium–sulfur (K–S) system using efficient sulfur-based cathodes. A free-standing flexible carbon nanotube/sulfur (CNT/S) composite cathode based on CNT film to form a conductive network on a sulfur substrate is proposed herein. The synthesized CNT/S composite takes advantages of the intercrossing microchannels of the conductive CNT networks, which clearly favors rapid charge transfer and enhanced active mass loading as well as the surface electrocatalytic effect in K–S batteries. The resulting self-supported CNT/S film cathode with high flexibility achieved high initial capacity of 585 mAh g⁻¹ at current density of 50 mA g⁻¹. The proposed CNT/S cathode system could thus be a promising candidate for further advancement of next-generation K–S power systems for practical applications.