Owing
to their low cost and abundant reserves, aluminum-ion batteries
(AIBs) have been considered a potential candidate for future large-scale
storage applications. However, AIBs are still in the stage of intensive
research due to their cathodes of limited specific capacity, energy
density, and cycling stability. In this work, interlayer-expanded
MoSe2/nitrogen-doped graphene (MoSe2/N-G) heterojunctions
with fewer layers and fine dispersion are synthesized by a facile
hydrothermal method. Experimental verification and theoretical calculation
reveal that the unique heterojunction structure and hetero-element
doped graphene conductive network are beneficial for improving the
electrochemical reaction kinetics and provide more active vacancies
for AIBs, as well as slow the structural degradation during the discharge/charge
process. When serving as a cathode material for AIBs, the as-prepared
MoSe2/N-G electrode presents a high specific capacity of
167 mAh g–1 at 0.2 A g–1. Meanwhile,
the hybrid also exhibits excellent cycling stability (140 mAh g–1 at 0.2 A g–1 after 1000 cycles)
with a high Coulombic efficiency of 99.54% and less than 16% loss
of discharge capacity. As verified by ex situ X-ray photoelectron
spectroscopy (XPS)/transmission electron microscopy (TEM) characterization
and first-principles calculations, the Al3+ intercalation
mechanism of the MoSe2/N-G electrode in AIBs are further
confirmed.