A Full Li-S Battery with Ultralow Excessive Li Enabled via Lithiophilic and Sulfilic W₂ C Modulation

The practical application of Li-S batteries demands low cell balance (Li_capacity /S_capacity ), which involves uniform Li growth, restrained shuttle effect, and fast redox reaction kinetics of S species simultaneously. Herein, with the aid of W₂ C nanocrystals, a freestanding 3D current collector is applied as both Li and S hosts owing to its lithiophilic and sulfilic property. On the one hand, the highly conductive W₂ C can reduce Li nucleation overpotentials, thus guiding uniform Li nucleation and deposition to suppress Li dendrite growth. On the other hand, the polar W₂ C with catalytic effect can enhance the chemisorption affinity to lithium polysulfides (LiPSs) and guarantee fast redox kinetics to restrain S species in cathode region and promote the utilization of S. Surprisingly, a full Li-S battery with ultralow cell balance of 1.5:1 and high sulfur loading of 6.06 mg cm^-2 shows obvious redox plateaus of S and maintains high reversible specific capacity of 1020 mAh g^-1 (6.2 mAh cm^-2 ) after 200 cycles. This work may shed new sights on the facile design of full Li-S battery with low excessive Li supply.