On the path to building better batteries, researchers have been choosing silicon as their material of choice to increase life-cycle and energy density. Silicon is favored among researchers because its anodes have the ability to store up to ten times the amount of lithium ions than conventional graphite electrodes. However, silicon is a rather rigid material, which makes it difficult for the battery to withstand volume changes during charge and discharge cycles.
This from Georgia Tech:
Using a combination of experimental and simulation techniques, researchers from the Georgia Institute of Technology and three other research organizations have reported surprisingly high damage tolerance in electrochemically-lithiated silicon materials. The work suggests that all-silicon anodes may be commercially viable if battery charge levels are kept high enough to maintain the material in its ductile state.
Power of Silicon
“Silicon has a very high theoretical capacity, but because of the perceived mechanical issues, people have been frustrated about using it in next-generation batteries,” said Shuman Xia, one of the authors of the study. “But our research shows that lithiated silicon is not as brittle as we may have thought. If we work carefully with the operational window and depth of discharge, our results suggest we can potentially design very durable silicon-based batteries.”
In or daily lives, we encounter lithium ion batteries almost constantly. From our smartphones to laptops to new vehicles, almost every electronic device we use is powered by a lithium ion battery. While these batteries have huge potential in smaller electronic devices, they have yet to make their way to the energy grid. With this new development, researchers hope lithium ion batteries could get one step closer to large-scale energy storage.
Looking at Lithium Ions
By analyzing silicon structures containing varying levels of lithium ions in a detailed nano-mechanical study, promising results for silicon-based electrodes were revealed. Through using a transmission electron microscope (TEM), the study showed that the silicon cores of the nanowires remained brittle, but the outside of the wire became more ductile as it absorbed the lithium.
“Our nanoindentation and TEM experiments were very consistent,” said Xia. “Both suggest that lithiated silicon material becomes very tolerant of damage as the lithium concentration goes above a certain level – a lithium-to-silicon molar ratio of about 1.5. Beyond this level, we can’t even induce cracking with very large indentation loads.”
The research has both fundamental and immediate applications for high-capacity lithium ion batteries.
Head over to the Digital Library to get more research on lithium ion batteries.
