The Effects
of Different Core–Shell Structures
on the Electrochemical Performances
of Si–Ge Nanorod Arrays as Anodes for Micro-Lithium Ion Batteries
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Abstract
Connected
and airbag isolated Si–Ge nanorod (NR) arrays
in different configurations have been fabricated on wafer scale Si
substrates as anodes in micro-lithium ion batteries (LIBs), and the
impacts of configurations on electrochemical properties of the electrodes
were investigated experimentally and theoretically. It is demonstrated
that the Si inner cores can be effectively protected by the connected
Ge shells and contribute to the enhanced capacity by ∼68%,
derived from an activation process along with the amorphization of
the crystalline lattice. The first-principles calculations further
verify the smaller forces on the Si layers at the atomic level during
the restricted volume expansion with the covering of Ge layers. This
work provides general guidelines for designing other composites and
core–shell configurations in electrodes of micro-LIBs to accomplish
higher capacities and longer cycle lives