Synergistically Accelerating Adsorption‐Electrocataysis of Sulfur Species via Interfacial Built‐In Electric Field of SnS<sub>2</sub>‐MXene Mott–Schottky Heterojunction in Li‐S Batteries
Li Chen, Liguo Yue, Xinying Wang, Shangyou Wu, Wei Wang, Dongzhen Lu, Xi Liu, Weiliang Zhou, Yunyong Li
Abstract
Abstract Developing efficient heterojunction electrocatalysts and uncovering their atomic‐level interfacial mechanism in promoting sulfur‐species adsorption‐electrocatalysis are interesting yet challenging in lithium‐sulfur batteries (LSBs). Here, multifunctional SnS 2 ‐MXene Mott–Schottky heterojunctions with interfacial built‐in electric field (BIEF) are developed, as a model to decipher their BIEF effect for accelerating synergistic adsorption‐electrocatalysis of bidirectional sulfur conversion. Theoretical and experimental analysis confirm that because Ti atoms in MXene easily lost electrons, whereas S atoms in SnS 2 easily gain electrons, and under Mott–Schottky influence, SnS 2 ‐MXene heterojunction forms the spontaneous BIEF, leading to the electronic flow from MXene to SnS 2 , so SnS 2 surface easily bonds with more lithium polysulfides. Moreover, the hetero‐interface quickly propels abundant Li + /electron transfer, so greatly lowering Li 2 S nucleation/decomposition barrier, promoting bidirectional sulfur conversion. Therefore, S/SnS 2 ‐MXene cathode displays a high reversible capacity (1,188.5 mAh g −1 at 0.2 C) and a stable long‐life span with 500 cycles (≈82.7% retention at 1.0 C). Importantly, the thick sulfur cathode (sulfur loading: 8.0 mg cm −2 ) presents a large areal capacity of 7.35 mAh cm −2 at lean electrolyte of 5.0 µL mg s −1 . This work verifies the substantive mechanism that how BIEF optimizes the catalytic performance of heterojunctions and provides an effective strategy for deigning efficient bidirectional Li‐S catalysts in LSBs.