A Rice University chemist and his students appear to have cracked the dendrites code, according to the website New Electronics. The leading research university is in Houston, Texas, and has a notable 6:1 student-faculty ratio. They explain that dendrites are like tentacles reaching out between the electrodes of lithium batteries. Now, the solution appears to be coating lithium-metal foil with multi-walled carbon nanotube film to stop the dendrites’ actions.
Prof James Tour of Rice University Explains
The faster you want to charge the battery, the quicker the dendrites grow, and the sooner you have a short circuit. Thus, one of the ways to slow dendrites in lithium-ion batteries is to limit how fast they charge. “People don’t like that,” the Rice University chemist says. “Because they want to be able to charge their batteries quickly.”
Therefore, lithium-metal batteries potentially have distinct advantages over lithium-ion ones. Since they charge faster and store ten times more energy by volume. If science can solve the dendrites issue we could be onto a winner. But if we don’t, something else will come along and leave lithium-metal behind. In fact, this is the single most important thing that has dampened commercial applications and research.
What We Did Turned Out Real Easy, Prof James Tour Explains
We may never know the spark of genius that inspired the Rice University research team to coat lithium metal foil with a multi-walled carbon nanotube film. However, we could try and understand the process. “The lithium doped the nanotube film. This turned from black to red, and the film in turn diffused the lithium ions” according to the research report.
We understand physical contact with lithium metal reduces the carbon nanotube film, but balances it by adding lithium ions. Postdoctoral researcher Rodrigo Salvatierra adds, “The ions distribute themselves throughout the nanotube film.” Then when the battery is in use, the film discharges stored ions and the underlying lithium anode refills it. This maintains the film’s ability to stop dendrite growth.
The team reports their innovation “effectively quenched dendrites over 580 charge / discharge cycles of a test battery.” Moreover the lithium-metal cells retained 99.8% of their electrons’ ability to travel through the electro-chemical system.
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Preview Image: James Tour, Gladys López-Silva and Rodrigo Salvatierra
