Stabilizing Lithium Metal Anode Enabled by a Natural Polymer Layer for Lithium-Sulfur Batteries

The lithium-sulfur (Li-S) battery with a high theoretical energy density (2560 Wh kg^-1) is one of the most promising candidates in next-generation energy storage systems. However, its practical application is impeded by the shuttle effect of lithium polysulfides, huge volume expansion, and overgrowth dendrite of lithium. Herein, we propose an artificial conformal agar polymer coating on a lithium anode (marked as A-Li). The functional layer facilitating the formation of a compact interphase on the lithium anode can effectively accommodate expansive volume and restrain the growth of dendritic lithium. The Li/Li symmetric cell with A-Li delivers stable plating/stripping cycling over 300 h at a high current density of 3.0 mA cm^-2 and a high fixed areal capacity of 3.0 mAh cm^-2. The cycle life of Li-Cu cells with A-Li is twice longer than that of pristine cells, and the Li-S batteries equipped with A-Li anodes also deliver an enhanced specific capacity and high Coulombic efficiencies. This work provides a pathway to protect metal Li anodes and contributes to the development of high-performance Li-S batteries.