Lithium Sulfide Batteries: Addressing the Kinetic Barriers and High First Charge Overpotential

Ever-rising global energy demands and the desperate need for green energy inevitably require next-generation energy storage systems. Lithium-sulfur (Li-S) batteries are a promising candidate as their conversion redox reaction offers superior high energy capacity and lower costs as compared to current intercalation type lithium-ion technology. Li₂S with a prelithiated cathode can, in principle, capture the high capacity while reducing some of the issues in conventional Li-S cells utilizing metallic lithium anodes and elemental sulfur cathodes. However, it also faces its own set of technical issues, including the insulating nature and the notorious shuttling effect that plagues the Li-S system. In addition, the high activation potential also hinders its electrochemical performance. To lower the high conversion barrier, key parameters of charge/ion transfer kinetics have to be considered in improving the reaction kinetics. This Review of lithium sulfide batteries examines the recent progress in this rapidly growing field, beginning with the revisiting of the fundamentals, working principles, and challenges of the Li-S system as well as the Li₂S cathode. The strategies adopted and methods that have been devised to overcome these issues are discussed in detail, by focusing on the synthesis of the nanoparticles, the structuring of the functional matrixes, and the promoting of the reaction kinetics through additives, aiming at providing a broad view of paths that can lead to a market viable Li₂S cathode in the near future.