From non-carbon host toward carbon-free lithium-sulfur batteries

Lithium-sulfur (Li-S) batteries with advantages of high energy densities (2600 Wh·kg−1/2800 Wh·L−1) and sulfur abundance are regarded as promising candidates for next-generation high-energy batteries. However, the conventional carbon host used in sulfur cathodes suffers from poor chemical adsorption towards Li-polysulfides (LPS) in liquid electrolyte and sluggish redox kinetics, leading to low capacity and rate capability. Besides, carbon host used in Li metal anode with the intrinsic property of poor lithiophilicity and high Li-nucleation barrier gives rise to uncontrollable dendrite growth and further battery failure. Therefore, non-carbon hosts with chemical adsorption toward LPS and catalytic activity for accelerating LPS redox conversion as well as lithiophilic property for guiding uniform Li deposition are proposed and demonstrated a high efficiency in both sulfur cathodes and Li metal anodes. In this review, the principle and challenges of Li-S batteries are first presented, then recent work using non-carbon hosts in Li-S batteries is summarized comprehensively, and the mechanism of non-carbon host in improving sulfur utilization and stabilizing Li metal anode is discussed in detail. Furthermore, remaining challenges and outlook on the implementation of non-carbon host for practical carbon-free Li-S batteries are also provided.