A Shell-Shaped Carbon Architecture with High-Loading Capability for Lithium Sulfide Cathodes.

Lithium sulfide (Li2S) is considered a highly attractive cathode for establishing high-energy-density rechargeable batteries, especially due to its high charge-storage capacity and compatibility with lithium-metal-free anodes. Although various approaches have recently been pursued with Li2S to obtain high performance, formidable challenges still remain with cell design (e.g., low Li2S loading, insufficient Li2S content, and an excess electrolyte) to realize high areal, gravimetric, and volumetric capacities. This study demonstrates a shell-shaped carbon architecture for holding pure Li2S, offering innovation in cell-design parameters and gains in electrochemical characteristics. The Li2S core-carbon shell electrode encapsulates the redox products within the conductive shell so as to facilitate facile accessibility to electrons and ions. The fast redox-reaction kinetics enables the cells to attain the highest Li2S loading of 8 mg cm−2 and the lowest electrolyte/Li2S ratio of 9/1, which is the best cell-design specifications ever reported with Li2S cathodes so far. Benefiting from the excellent cell-design criterion, the core-shell cathodes exhibit stable cyclability from slow to fast cycle rates and, for the first time, simultaneously achieve superior performance metrics with areal, gravimetric, and volumetric capacities. [ABSTRACT FROM AUTHOR]