Magnesium hydride nanoparticles anchored on MXene sheets as high capacity anode for lithium-ion batteries

Abstract

Magnesium hydride, with high specific capacity, favorable voltage profile and low voltage hysteresis properties, is regarded as a promising anode for lithium storage. However, the rapid fading of capacity caused by huge volume change, low electron/ion conduction, and spontaneous agglomeration of active materials during cycling greatly limit its practical application in lithium-ion batteries. Herein, we report the synthesis of monodisperse MgH2 nanoparticles with an average particle size of <20 nm homogeneously anchored on Ti3C2 MXene sheets by bottom-up self-assembly strategy. The unique nanoarchitectures are able to efficiently enhance the lithium insertion/extraction kinetics, accelerate the electron/lithium ion transfer and buffer the strain of volume changes. More importantly, the formed F–Mg bounding between MgH2 and MXene could avoid the shedding of MgH2 nanoparticles to electrolyte during cycling, which significantly enhance the capacity, cyclability, and rate performance of magnesium hydride. Moreover, due to the high density of MXene and the synergistic effect between the MgH2 and MXene matrix, the MgH2/MXene composite with 60 wt% MgH2 delivers a superior volumetric capacity of 1092.9 mAh cm−3 at a current density of 2000 mA g−1 after 1000 cycles. These results highlight the great promising of MgH2/MXene composite for high performance lithium-ion batteries.