Role of binary metal chalcogenides in extending the limits of energy storage systems: Challenges and possible solutions

Binary metal chalcogenides (BMCs) have shown better electrochemical performance compared with their mono metal counterparts owing to their abundant phase interfaces, higher active sites, faster electrochemical kinetics and higher electronic conductivity. Nevertheless, their performance still undergoes adverse decline during electrochemical processes mainly due to poor intrinsic ionic conductivities, large volume expansions, and structural agglomeration and fracture. To tackle these problems, various strategies have been applied to engineer the BMC nanostructures to obtain optimized electrode materials. However, the lack of understanding of the electrochemical response of BMCs still hinders their large-scale application. This review not only highlights the recent progress and development in the preparation of BMC-based electrode materials but also explains the kinetics to further understand the relation between structure and performance. It will also explain the engineering of BMCs through nanostructuring and formation of their hybrid structures with various carbonaceous materials and three-dimensional (3D) templates. The review will discuss the detailed working mechanism of BMC-based nanostructures in various electrochemical energy storage (EES) systems including supercapacitors, metal-ion batteries, metal-air batteries, and alkaline batteries. In the end, major challenges and prospective solutions for the development of BMCs in EES devices are also outlined. We believe that the current review will provide a guideline for tailoring BMCs for better electrochemical devices.