Constructing a Conductive Mott–Schottky Heterostructure with Built-in Electric Field Effect As Modified Separator to Accelerate Bidirectional Redox Kinetics for High-Performance Lithium–Sulfur Batteries

Developing efficient heterostructure electrocatalysts presents great potential but challenges in facilitating the bidirectional sulfur redox reaction due to the unsatisfactory trapping–diffusion–conversion capability and ambiguous interfacial mechanism for lithium–sulfur (Li–S) electrochemistry. Herein, the interfacial electron redistribution is modulated via the construction of a multifunctional ZnTe-MXene/NC heterostructure with a metallic-semiconductor phase to accelerate the overall redox reaction kinetics. Theoretical and experimental results demonstrate that the electron delocalization is enhanced under the interfacial built-in electric field effect, with electrons flowing from the side of MXene to ZnTe. The accumulated electrons on the ZnTe side reinforce the chemical interaction with lithium polysulfides (LiPSs) via the formation of Li–Te and metal–S bonds. In addition, the solid–liquid decomposition of Li2S is kinetically accelerated due to the weakened Li–S bonding, thereby realizing the superior bidirectional redox capability. Consequently, the ZnTe-MXene/NC-based batteries exhibit a high capacity of 690 mAh g–1 at 4 C and an ultrastable cyclic ability with a 0.042% decay rate per cycle at 3 C over 900 cycles. Even under a high-sulfur loading of 6.0 mg cm–2, a favorable areal capacity of 4.8 mAh cm–2 at 0.2 C after 150 cycles is maintained. This study proposes an underlying mechanism of MXene/telluride heterostructure electrocatalysts for multistep electrochemical reactions.