(Invited) Li-S Battery and Beyond Systems: Composite Cathodes, Li Anodes and Prospects

Abstract

Rechargeable Li metal batteries including Li-S, and Li-O2 batteries have become attractive candidates for the next-generation rechargeable electrochemical energy storage systems with high-energy densities because of their high theoretical energy densities and cost effectiveness. Here, we report our recent progress in Li-S and Li-Se batteries including S-C and Se-C composite cathodes, Li metal anodes, and the electrode/electrolyte interfaces. In contrast to the extensive studies of the electrochemical behavior of conventional cyclic S8 molecules in Li-S batteries, there has been hardly any investigation of the electrochemistry of S chains. Here we use S chains encapsulated in single- and double-walled carbon nanotubes as a model system and report the electrochemical behavior of 1D S chains in Li-S batteries. In addition, rational design of S-C composite cathodes with high sulfur loading and remarkable electrochemical properties will also be reported. On lithium metal anode we show that a 3D current collector with a submicron skeleton and high electroactive surface area can significantly improve the electrochemical deposition behavior of Li. Li anode is accommodated in the 3D structure without uncontrollable Li dendrites. We also demonstrate that an artificial SEI layer with high Young’s modulus can restrain Li dendrite growth and reduce the side reaction between Li metal and the organic electrolyte.