Anode Material Options Toward 500 Wh kg^-1 Lithium-Sulfur Batteries

Lithium-sulfur (Li-S) battery is identified as one of the most promising next-generation energy storage systems due to its ultra-high theoretical energy density up to 2600 Wh kg^-1 . However, Li metal anode suffers from dramatic volume change during cycling, continuous corrosion by polysulfide electrolyte, and dendrite formation, rendering limited cycling lifespan. Considering Li metal anode as a double-edged sword that contributes to ultrahigh energy density as well as limited cycling lifespan, it is necessary to evaluate Li-based alloy as anode materials to substitute Li metal for high-performance Li-S batteries. In this contribution, the authors systematically evaluate the potential and feasibility of using Li metal or Li-based alloys to construct Li-S batteries with an actual energy density of 500 Wh kg^-1 . A quantitative analysis method is proposed by evaluating the required amount of electrolyte for a targeted energy density. Based on a three-level (ideal material level, practical electrode level, and pouch cell level) analysis, highly lithiated lithium-magnesium (Li-Mg) alloy is capable to achieve 500 Wh kg^-1 Li-S batteries besides Li metal. Accordingly, research on Li-Mg and other Li-based alloys are reviewed to inspire a promising pathway to realize high-energy-density and long-cycling Li-S batteries.