In-situ construction of conducting alloy interphase towards modulating Li-ion storage kinetics

Abstract

Abstract Interface engineering strategy shows great promise in promoting the reaction kinetic and cycling performance in the field of electrochemical energy storage application. In this work, an in-situ interface growth strategy is proposed to introduce a robust and conducting MoGe2 alloy interphase between the electrochemical active Ge nanoparticle and flexible MoS2 nanosheets to modulate their Li-ion storage kinetics. The structural evolution processes of the Ge@MoGe2@MoS2 composite are unraveled, during which the initially-generated Ge metals serve as a crucial reduction mediator in the formation of MoGe2 species bridging the Ge and MoS2. The as-generated MoGe2 interface, chemically bonding with both Ge and MoS2, possesses multi-fold merits, including the maintaining stable framework of electrochemically inactive Mo matrix to buffer the strain-stress effect and the “welding spot” effects to facilitate the efficient Li+/e− conduction. As well, the introduction of MoGe2 interface leads to a unique sequential lithiation/de-lithiation process, namely in the order of the electrochemically active MoS2-MoGe2-Ge during lithiation and vice versa, during which the electrode strain could be more effectively released. Benefited from the robust and rigid MoGe2 interface, the delicately designed Ge@MoGe2@MoS2 composite exhibits an improved charge/discharge performances (866.7 mAh g−1 at 5.0 A g−1 and 838.5 mAh g−1 after 400 cycles) while showing a high tap density of 1.23 g cm−3. The as-proposed in-situ interface growth strategy paves a new avenue for designing novel high-performance electrochemical energy storage materials.