Improving Lithium-Ion Batteries with Nanowires

New research led by electrical engineer Shadi Dayeh of the University of California, San Diego is aimed at improving lithium-ion batteries through possible new electrode architectures with precise nano-scale designs. Dayeh's team 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. This work could lead to "an effective way to tailor volume expansion of lithium ion battery electrodes which could potentially minimize their cracking, improve their durability, and perhaps influence how one could think about different electrode architectures," says Dayeh. This video shows the axial lithiation of a silicon-coated nanowire's germanium core, as well as radial diffusion of lithium into an uncoated germanium nanowire.

Transcript

00:00:11 uh in the first video where we see two nanowires one of them has a lithium metal that's connected just at the tip of the wire and as we play the video we start to see that a lighter contrast starts to appear at the surface of the wire that means that lithium ions are diffusing from the surface into the nonwire core so this is where we don't have any chemical potential barrier on

00:00:37 the surface of the wire and and this process continues until we lithiate or diffuse lithium into the wire throughout the whole length and you can see that the wire is expanding radially now when we look at the second video where we have a single wire that has a uh small narrower region at its tip which is silicon but then the rest of the wire is a germanium silicon cor shell

00:01:04 wire as lithium ions reach the uh second segment which is the longest one a germanium silicon Corell wire you start to observe that the lighter contrast proceeds um axially into the wire it's not from the surface the lighter contrast eats one Atomic layer by one Atomic layer into the uh crystalline germanium core of the wire and the expansion in this case uh happens uh

00:01:33 axially along the length of the wire as opposed to radially where uh which we have just seen for the case of germanium if these wires are put in parallel of an electrode material then we can accommodate a larger um uh number of lithium ions uh into the electrode material without having to sort the two electrodes together of the battery and um more than this a little bit further

00:02:02 this allows us to uh to think out of the box about ways in which we can store and extract lithium into storage materials by introducing this concept of heterostructuring in the storage material itself so this uses interface and bed Gap engineering basically to modulate the barriers that can allow lithium ion to go in one preferable Direction

00:02:32 compared to the other and that can ultimately help us find the perfect architecture for the uh longest dur durability and highest capacity uh lithium ion battery