Lithium Sulfide (Li2S)-Metal Nanocomposites

Lithium sulfide (Li2S) is considered a highly attractive cathode for establishing high-energy–density rechargeable batteries because of its high theoretical capacity (1167 mA h g−1), low cost, and compatibility with lithium-free anodes. In addition, since Li2S is a fully lithiated state of sulfur, Li2S cathode alleviates the volume expansion challenge commonly encountered in the sulfur cathode. Moreover, Li2S cathode coupled with lithium-free anodes provides a promising approach for overcoming the safety problems of the metallic lithium anode and thereby holds high potential for commercial applications. However, its inert electrochemical nature causes large activation overpotential in the initial charge process. The electrochemistry of Li2S cathode suffers low conductivities (both electronic and ionic) and polysulfides shuttle effect. Metal nanocomposites have interesting characteristics of good conductivity, electrochemical and catalytic properties. These intriguing properties of metal nanocomposites make them suitable for designing and developing Li2S-metal nanocomposite cathodes. As a result, proper designing of the Li2S-based cathode with metal nanocomposites is crucial for activating the Li2S cathode in the initial charge process and improving the electrochemical performance of Li2S-based batteries.