Advanced preparation and application of bimetallic materials in lithium-sulfur batteries: A review

Lithium-sulfur (Li-S) batteries are considered highly promising as next-generation energy storage systems due to high theoretical capacity (2600 W h kg−1) and energy density (1675 mA h g−1) as well as the abundant natural reserves, low cost of elemental sulfur, and environmentally friendly properties. However, several challenges impede its commercialization including low conductivity of sulfur itself, the severe “shuttle effect” caused by lithium polysulfides (LiPSs) during charge-discharge processes, volume expansion effects and sluggish reaction kinetics. As a solution, polar metal particles and their compounds have been introduced as the main hosts for sulfur cathode due to their robust catalytic activity and adsorption capability, effectively suppressing the “shuttle effect” of LiPSs. Bimetallic alloys and their compounds with multi-functional properties exhibit remarkable electrochemical performance more readily when compared to single-metal materials. Well-designed bimetallic materials demonstrate larger specific surface areas and richer active sites, enabling simultaneous high adsorption capability and strong catalytic properties. The synergistic effect of the “adsorption-catalysis” sites accelerates the adsorption-diffusion-conversion process of LiPSs, ultimately achieving a long-lasting Li-S battery. Herein, the latest progress and performance of bimetallic materials in cathodes, separators, and interlayers of Li-S batteries are systematically reviewed. Firstly, the principles and challenges of Li-S batteries are briefly analyzed. Then, various mechanisms for suppressing “shuttle effects” of LiPSs are emphasized at the microscale. Subsequently, the performance parameters of various bimetallic materials are comprehensively summarized, and some improvement strategies are proposed based on these findings. Finally, the future prospects of bimetallic materials are discussed, with the hope of providing profound insights for the rational design and manufacturing of high-performance bimetallic materials for LSBs.