Performance Study of MXene/Carbon Nanotube Composites for Current Collector- and Binder-Free Mg-S Batteries.

The realization of sustainable and cheap Mg-S batteries depends on significant improvements in cycling stability. Building on the immense research on cathode optimization from Li-S batteries, for the first time a beneficial role of MXenes for Mg-S batteries is reported. Through a facile, low-temperature vacuum-filtration technique, several novel current collector- and binder-free cathode films were developed, with either dipenthamethylene thiuram tetrasulfide (PMTT) or S nanoparticles as the source of redox-active sulfur. The importance of combining MXene with a high surface area co-host material, such as carbon nanotubes, was demonstrated. A positive effect of MXenes on the average voltage and reduced self-discharge was also discovered. Ascribed to the rich polar surface chemistry of Ti C T MXene, an almost doubling of the discharge capacity (530 vs. 290 mA h g ) was achieved by using MXene as a polysulfide-confining interlayer, obtaining a capacity retention of 83 % after 25 cycles.