The researchers created nanowires that block diffusion of lithium (Li) across their silicon surface and promote layer-by-layer axial lithiation of the nanowire’s germanium core.
Shadi Dayeh, a professor in the Department of Electrical and Computer Engineering at the UC San Diego Jacobs School of Engineering, explained in a statement that this work could lead to ‘an effective way to tailor volume expansion of lithium ion battery electrodes which could potentially minimise their cracking, improve their durability, and perhaps influence how one could think about different electrode architectures.’
The research was recently published in the journal Nano Letters in the paper Tailoring Lithiation Behavior by Interface and Bandgap Engineering at the Nanoscale.
By coating germanium nanowires with silicon, the researchers stopped nearly all surface diffusion of lithium ions into the nanowires. Instead, lithium diffusion (lithiation), occurred layer by layer along the axis of the nanowire. This is in contrast to lithiation from the surface of nanowires not covered with silicon.
‘These results demonstrate for the first time that interface and bandgap engineering of electrochemical reactions can be utilised to control the nanoscale ionic transport/insertion paths and thus may be a new tool to define the electrochemical reactions in Li-ion batteries,’ the researchers write in their Nano Letters paper.
Funding for this research includes Nanostructures for Electrical Energy Storage (NEES), an Energy Frontier Research Center (EFRC) funded by the US Department of Energy, Los Alamos National Laboratory, Sandia National Laboratories, and UC San Diego.
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