Potentiostatic way to fabricate Li₂S_x cathode with suppressed polysulfide formation

The usage of Li metal in lithium sulfur (Li-S) battery has largely hampered the application of Li-S battery due to the formation of Li dendrite during cycling. Here, a novel potentiostatic (p-stat) lithiation method was developed to fabricate Li₂S_x cathode. The pre-lithiated Li₂S_x cathode can be used to pair with the Li metal free anode to make a full cell with better safety. The dissolution of the polysulfide in electrolyte is the main problem in S cathode, which leads to severe active material loss during lithiation process. Normally, the way to alleviate the dissolution of polysulfide is by trapping the polysulfide from diffusing into the electrolyte. In this work, it is innovatively raised the p-stat lithiation method which can suppress the formation of polysulfides. As a result, dissolution of polysulfide species could be kinetically suppressed. The p-stat lithiated Li₂S_x cathode exhibits higher capacity performance (around 400 mAh g⁻¹) than the galvanostatic (g-stat) lithiated Li₂S_x cathode. The Li metal free full cell assembled by pairing p-stat lithiated Li₂S_x cathode with graphite anode shows stable cyclability.