Zhang Baoping, Si Yinsong, Gu Qinfen, Chen Min, Yu Xuebin
Department of Materials Science , Fudan University , Shanghai 200433 , China.
School of Energy and Environment , City University of Hong Kong , Tat Chee Avenue , Kowloon 999077 , Hong Kong , China.
ACS Appl Mater Interfaces. 2019 Aug 14;11(32):28987-28995. doi: 10.1021/acsami.9b10527. Epub 2019 Jul 31.
Magnesium hydride (MgH) 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 MgH 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 MgH 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 MgH 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 after 1000 cycles at a high current rate of 2 A g, enabling it a potential anode candidate for LIBs.
氢化镁（MgH）凭借其高理论比容量、适宜的电位和丰富的来源，是一种很有前景的锂离子电池（LIBs）负极材料。然而，由于其电子导电性差和容量快速衰减，MgH电极的电化学性能仍远不能令人满意。本文制备了一种绣球花状三维（3D）分级氢化镁-碳骨架（MH@HyC），它由均匀自组装在分级多孔碳（HyC）上的MgH纳米颗粒（NPs）组成，用于先进的锂存储。HyC具有高比表面积和明确的大-中-微孔结构，对MgH NPs的生长起到了理想的结构导向作用，能够控制其尺寸、实现高负载并形成绣球花状阵列。利用其坚固的3D分级多孔结构和衍生的相互作用，MH@HyC不仅提供了足够的电化学活性位点，增强了电子导电性以及电子/锂离子快速传输的通道，还缓解了团聚现象并适应了循环过程中的体积效应，从而实现了高容量利用率、快速的电化学动力学以及良好维持的结构完整性。结果，MH@HyC在2 A g的高电流密度下循环1000次后，可逆容量高达554 mAh g，使其成为LIBs潜在的负极候选材料。
