Electrochemically Active MoO₃/TiN Sulfur Host Inducing Dynamically Reinforced Built-in Electric Field for Advanced Lithium–Sulfur Batteries

Although various electrocatalysts have been developed to ameliorate the shuttle effect and sluggish Li–S conversion kinetics, their electrochemical inertness limits the sufficient performance improvement of lithium–sulfur batteries (LSBs). In this work, an electrochemically active MoO₃/TiN-based heterostructure (MOTN) is designed as an efficient sulfur host that can improve the overall electrochemical properties of LSBs via prominent lithiation behaviors. By accommodating Li ions into MoO₃ nanoplates, the MOTN host can contribute its own capacity. Furthermore, the Li intercalation process dynamically affects the electronic interaction between MoO₃ and TiN and thus significantly reinforces the built-in electric field, which further improves the comprehensive electrocatalytic abilities of the MOTN host. Because of these merits, the MOTN host-based sulfur cathode delivers an exceptional specific capacity of 2520 mA h g⁻¹ at 0.1 C. Furthermore, the cathode exhibits superior rate capability (564 mA h g⁻¹ at 5 C), excellent cycling stability (capacity fade rate of 0.034% per cycle for 1200 cycles at 2 C), and satisfactory areal capacity (6.6 mA h cm⁻²) under a high sulfur loading of 8.3 mg cm⁻². This study provides a novel strategy to develop electrochemically active heterostructured electrocatalysts and rationally manipulate the built-in electric field for achieving high-performance LSBs.