Abstract
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Metal hydrides have attracted great intentions
as anodes for lithium-ion batteries (LIBs) due to their
extraordinary theoretical capacity. It is an unsolved challenge,
however, to achieve high capacity with stable cyclability,
owing to their insulating property and large volume expansion
upon lithium storage. Here, we introduce self-initiated
polymerization to realize molecular-scale functionality of
metal hydrides with conductive polymer, that is, polythiophene
(PTh), on graphene, leading to the formation of
MgH2@PTh core−shell nanoparticles on graphene. The
nanoscale characteristics of MgH2 not only relieve the
induced stress upon volume changes but also allow fast
diffusivity and high reactivity for Li-ion transport. More importantly, the conformal coating of ultrathin PTh membrane
can effectively suppress the detrimental reactions between MgH2 and electrolyte, provide enhanced performance with
facile electron and Li+ transport, and preserve its structural integrity, attributed to the strong molecular interaction
between PTh and MgH2 as well as its various products during electrochemical reactions. With this structure, a high
reversible specific capacity of 1311 mAh g−1 at 100 mA g−1, excellent rate performance of 1025 mAh g−1 at 2000 mA g−1,
and a capacity retention of 84.5% at 2000 mA g−1 after 500 cycles are observed for MgH2@PTh nanoparticles as anode for
LIBs.