While Li₂S cathodes are extremely attractive due to their high theoretical capacity (1166 mAh/g), low cost, and compatibility with non-lithium metal anodes, the lithiation/delithiation reaction pathway between Li₂S and S includes the formation of soluble polysulfides, which leads to poor cycle life.  One strategy to improve cycle life is to coat Li₂S particles with a protective layer, preventing polysulfide dissolution.

Leveraging a proprietary high-throughput synthesis workflow, Wildcat Discovery Technologies has demonstrated the reactive deposition of an inorganic coating onto Li₂S particles.  The coating method, based on the reaction of precursors with Li₂S, is shown to be a general method and used to deposit coatings with different compositions on the surface of Li₂S. Galvanostatic cycling of coated cathodes shows reduced formation of soluble polysulfides which in turn increases cycle life with 95% capacity retention between cycles 1-3 and also improves long term cycle life. This coating also improves conductivity thus improving cycle 1 discharge capacity. The approach described in this presentation is unique in: 1) it focuses on the charged state of the cathode versus the uncharged state (Li₂S vs S) which would enable cell chemistries that do not rely on a Li metal anode, 2) it is a novel type of coating for the active material which is compatible with any base Li₂S, and 3) demonstrates the power of high-throughput screening in developing new chemistries for next generation batteries.