Hydrangea-Shaped 3D Hierarchical Porous Magnesium Hydride-Carbon Framework with High Rate Performance for Lithium Storage.

Magnesium hydride (MgH2) is a promising anode material for lithium-ion batteries (LIBs) by virtue of its high theoretical specific capacity, suitable potential, and abundant source. However, the electrochemical performance of the MgH2 electrode is still far from satisfactory due to its poor electronic conductivity and fast capacity decay. In this paper, a hydrangea-shaped three-dimensional (3D) hierarchical magnesium hydride-carbon framework (MH@HyC) comprising MgH2 nanoparticles (NPs) uniformly self-assembled on hierarchical porous carbon (HyC) is fabricated for advanced lithium storage. Featuring high surface area and a well-defined macro-meso-micropore structure, HyC plays an ideal structure-directing role for the growth of MgH2 NPs with size control, high loading, and a hydrangea-shape array. Taking advantage of the robust 3D hierarchical porous structure and the derived interactions, MH@HyC not only provides sufficient electrochemically active sites and enhances the electronic conductivity and channels for rapid transfer of electrons/Li ions but also relieves the agglomeration and accommodates the volumetric effects during cycling, leading to high capacity utilization, fast electrochemical kinetics, and well-sustained structural integrity. As a result, MH@HyC delivers a high reversible capacity of 554 mAh g-1 after 1000 cycles at a high current rate of 2 A g-1, enabling it a potential anode candidate for LIBs.