Built-in electric field-driven bifunctional ZnSe-SnO₂/C heterostructure for regulating polysulfide conversion and lithium deposition

Severe polysulfide shuttling, sluggish redox kinetics, and uncontrolled lithium dendrite growth are key impediments to lithium‑sulfur (LiS) batteries. Here, we construct a hollow cubic ZnSe-SnO₂/C heterostructure as a multifunctional coating to regulate polysulfide conversion and lithium deposition processes. The difference in work functions of ZnSe and SnO₂ drives interfacial charge redistribution, giving rise to a built-in electric field (BIEF) that accelerates charge transport. Benefiting from the induced BIEF and the catalytic synergy between ZnSe and SnO₂, the ZnSe-SnO₂/C heterojunction is experimentally and theoretically demonstrated to enhance polysulfide immobilization and accelerate sulfur conversion kinetics. Meanwhile, the BIEF-enabled heterojunction exhibits strong lithiophilicity, lowering the lithium nucleation barrier. It also regulates Li⁺ flux to enable stable lithium deposition. Thus, the assembled LiS battery stands out in rate performance, delivering 771.1 mAh g^-1 at 6C. It also exhibits prolonged durability, with a capacity loss of merely 0.067% per cycle over 600 cycles at 5C. Even under a sulfur loading of 5.55 mg cm^-2 with a lean electrolyte of 8.10 μL mg^-1, an areal capacity as high as 6 mAh cm^-2 is still achieved. Moreover, stable operation of the Li||Li cell is maintained over 1000 h at 3 mA cm^-2. Importantly, a BIEF-enabled interfacial regulation strategy is developed to modulate sulfur electrochemistry and lithium deposition behavior.