Rational structure designs of 2D materials and their applications toward advanced lithium-sulfur battery and lithium-selenium battery

Lithium-sulfur (Li-S) and lithium-selenium (Li-Se) batteries have gradually triggered enormous attention in the field of secondary energy conversion and storage due to excellent theoretical capacities and advanced theoretical energy densities, which are nearly an order of magnitude higher than widely used lithium ion battery. But the commercialization processes of Li-S/Se batteries are slow due to the poor conductivity of elemental S/Se and insoluble low-order lithium polysulfides (polyselenides), severe shuttle effect of soluble high-order lithium polysulfides (polyselenides) and slow reaction kinetics during the process of redox reaction. Nowadays, the rationally designed two dimensional (2D) materials in the compositions of Li-S/Se batteries have presented conspicuous merits and can greatly enhance the electrochemical performances of the batteries. This review firstly highlights the distinctive structural merits of various 2D materials for advanced Li-S/Se cells. Then an overview of recent advances in the designs and preparations of different 2D materials with well-designed shapes, tailored structures, selective chemical constituents and their corresponding electrochemical properties combining the physical confinement, chemical adsorption, catalytic effect et al. Finally, some challenges and viewpoints in this field are also discussed. The comprehensive review will help researchers to well learn rational designs including modification based on structure and engineering of 2D materials for effectively enhancing electrochemical performances of Li-S/Se cells, which eventually lead the batteries to be a practically commercial applications for power source.