Ni-Bridged Biphasic Molybdenum Carbide Interfaces: A Synergistic Catalyst for High-Performance Lithium-Selenium Batteries.

Transition metal catalysts are key to developing high-performance lithium-selenium (Li-Se) batteries. Herein, we report a rationally designed Ni-bridged biphasic molybdenum carbide (Mo2C) with a multi-interface structure that exposes abundant active sites and significantly enhances the electrochemically reversibility of Li-Se batteries under high current operation. The synergistic integration of catalytic and conductive functions facilitates the rapid deposition and conversion of Se/Li2Sex, effectively preventing electrode passivation caused by inactive accumulation during high-rate and long-term cycling. Furthermore, Ni serves dual roles as a structural bridge to link Mo2C lattice and an electronic modulator to optimize the d-orbital configuration of Mo, thereby maximizing the catalytic efficiency of functionalized Mo2C. The synergistic effects of adsorption, desorption, and catalysis enable the rationally designed metal carbide/Se electrode to promote not only the rapid conversion of long-chain Li2Sen species but also the solid-solid transformation of Li2Se2 into Li2Se. As a result, the electrode achieves full-process catalytic conversion in Li-Se batteries, delivering excellent cycling stability and high-rate performance. Even under high Se loading (5.6 mg cm-2), the electrode delivers an initial capacity of 400 mAh g-1 at 0.1 C. These results highlight the effectiveness of the synergistic adsorption/desorption/catalysis mechanism in enabling a fast solid-solid conversion pathway for Li-Se batteries.