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Mumbai: Researchers at the University of California, Riverside’s Bourns College of Engineering have developed a lithium-ion battery, which they claim outperforms the current industry standard by three times.

And the material they used is sand. Yes. You read it right.

“This is the holy grail—a low-cost, non-toxic, environmentally friendly way to produce high performance lithium-ion battery anodes," said Zachary Favors, a graduate student working with Cengiz and Mihri Ozkan, both engineering professors at UC Riverside, in a release on 8 July.

Favors said he got the idea six months ago when relaxing on a beach in California, and playing with sand.

A lithium-ion battery comprises an electrolyte that transports lithium ions back and forth between the negative electrode (anode) that typically uses lithium and the positive electrode (cathode) that traditionally uses graphite—both of which are kept apart by a separator. When connected to a device, they cause an electrochemical reaction.

With his research centred on building better lithium-ion batteries, Favors focused on the anode, or negative side of the battery, which traditionally uses graphite. Researchers have also done research on using silicon at the nanoscale, or billionths of a metre, level to substitute graphite. Silicon is said to store 10 times more energy than graphite but the problem with nanoscale silicon is that it degrades quickly and is hard to produce in large quantities.

Back in his lab, Favors looked at sand with a high percentage of quartz and purified it. He then ground salt and magnesium into the purified quartz, and heated the mixture. With the salt acting as a heat absorber, the magnesium worked to remove the oxygen from the quartz, resulting in pure silicon.

The sponge-like porosity of the silicon, a quality that allows liquid or air to pass through minute spaces or holes, proved to be the key to improving the performance of the batteries built with the nano-silicon.

The improved performance could mean expanding the expected lifespan of silicon-based electric vehicle batteries up to three times or more, which would be significant for consumers, considering replacement batteries cost thousands of dollars, the release said.

For cellphones or tablets, it could mean having to recharge every three days, instead of every day.

The findings were recently published in a paper, Scalable Synthesis of Nano-Silicon from Beach Sand for Long Cycle Life Li-ion Batteries, in the journal Nature Scientific Reports.

The Ozkan team is trying to produce larger quantities of the nano-silicon from beach sand and is planning to move from coin-size batteries to pouch-size batteries that are used in cellphones.

In a related development, Pacific Northwest National Laboratory (PNNL) researchers too have developed a porous material to replace graphite with silicon in electrodes.

A paper describing the material’s performance as a lithium-ion battery electrode was published in Nature Communications on 8 July.

“Silicon has long been sought as a way to improve the performance of lithium-ion batteries, but silicon swells so much when it is charged that it can break apart, making a silicon electrode inoperable," said PNNL fellow Ji-Guang “Jason" Zhang in a statement on Tuesday.

Zhang and his PNNL colleagues wanted to work on a sponge-like silicon electrode, so they asked Michael Sailor, a University of California, San Diego chemist whose research includes using porous silicon to detect pollutants and deliver drugs, for help.

PNNL used Sailor’s method to create porous silicon—placing thin sheets in a chemical bath to etch out tiny holes throughout the material—and then coated the result with a thin layer of conductive carbon to make their electrodes.

The team then collaborated with materials scientist Chongmin Wang, who specializes in using in-situ transmission electron microscopes at Department of Energy’s Environmental Molecular Sciences Laboratory, located at PNNL.

Wang, with the help of microscopes that record close-up videos of tiny batteries to allow researchers better understand the physical and chemical changes that batteries undergo, observed that the team’s sponge-like, carbon-coated silicon electrode maintained more than 80% of its initial energy storage capacity.

Zhang and his colleagues, according to the release, now plan to develop a larger prototype battery with their silicon sponge electrode.

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