2D Light-Weight Transition Metal Disulfide as Model Cathode for Alkali-Ion Batteries and Beyond

The capacity of rechargeable battery is mainly controlled by two factors: maximum number of ions that can be held by an electrode material and its weight. In general, the weight and hence the specific capacity of a battery is mainly affected by the cathode material. In this context, Sc, the lightest transition metal, could prove helpful in achieving the goal of high theoretical capacity. Therefore, here the performance of two-dimensional (2D) ScS2 nanosheets (both hexagonal-H and trigonal-T) as cathode materials for alkali-ion batteries (Li, Na, and K) and other multivalent metal-ion batteries (Mg and Al) is studied. The first-principles calculations show that 2D H and TScS2 nanosheets deliver large theoretical capacity of 491.36 mA h g-1 for alkali ions and 324.29 m'A h g-1 for Mg and Al ions while maintaining good average open-circuit voltages. Results also suggest low diffusion barriers for all metal ions except Al, with TScS2 exhibiting ultra-low barriers for alkali atoms. Overall, this study provides a fundamental and a comprehensive view on the potential capabilities of both HScS2 and TScS2 by defining the underlying mechanism from the perspective of a cathode material which may prove helpful in designing light-weight and high-capacity transition metal sulfide-based metal-ion batteries in the future. Light-weight cathode materials can increase the specific capacity of a battery, therefore, lightest transition metal sulfide (ScS2), in nanosheet form is examined as a cathode material for alkali-ion and multivalent metal-ion batteries. A fundamental and comprehensive view of the potential capabilities of both hexagonal and trigonal phases by defining the underlying mechanism is presented to design light-weight and high-capacity batteries.image