NbO2 a Highly Stable, Ultrafast Anode Material for Li- and Na-Ion Batteries

Topochemically synthesized Nb3VS6 as a stable anode for sodium-ion batteries

Ternary metal sulfides having layered morphology are considered as potential active materials for various applications. Herein, Nb3VS6 is synthesized topochemically for the first time using a Nb-V-HDA complex having a lamellar structure by employing H2S gas as the sulfidation agent. Nb3VS6, as an anode for SIBs, exhibited a specific capacity of 101.15 mA h g-1 at 0.5 A g-1, along with excellent cycling stability with 100% capacity retention after 2500 cycles.

Rhombohedrally stacked layered transition metal dichalcogenides and their electrocatalytic applications

Layered transition metal dichalcogenides (TMDCs) are extensively investigated as catalyst materials for a wide range of electrochemical applications due to their high surface area and versatile electronic and chemical properties. Bulk TMDCs are van der Waals solids that possess strong in-plane bonding and weak inter-layer interactions. In the few-layer 2D TMDCs, several polymorphic structures have been reported as each individual layer can either retain octahedral or trigonal prismatic coordination. Among them, 1T (tetragonal), 2H (hexagonal) and 3R (rhombohedral) phases are very common. These polymorphs can display discrepancies in their catalytic activity as their electronic structure diverges due to different d orbital filling states. The broken inversion symmetry and large exposed edge sites of some of the 3R-phase TMDCS such as MoS2, NbS2 and TaS2 appear to be advantageous for electrocatalytic water reduction and battery applications. We describe recent studies in phase engineering of 2D TMDCs, particularly aiming at the 3R polytype and their electrocatalytic properties. Redox ability primarily depends on a distinct polymorphic phase in which TMDCs are isolated, and hence, with rich polymorphic structures being reported, numerous new catalytic applications can be realized. Phase conversion from 2H to 3R phase in some TMDCs enhances structural integrity and establishes robustness under harsh chemical conditions.

3R-NbS2 as a highly stable anode for sodium-ion batteries

Anode materials for advanced sodium-ion batteries (SIBs) require major improvements with regard to their cycling stability, which is a crucial parameter for long-term battery operation. Herein, we report 3R-NbS2, synthesised by a simple solid-state annealing route, as an anode for SIBs with remarkable cycling stability for 2500 cycles at 0.5 A g-1. The stable nature of the NbS2 anode was attributed to its dominant capacitive behaviour.