Using sand as an anode, triple the performance for Li-ion batteries

The anode of Lithium-ion (Li-ion) batteries is usually made of graphite but not many people believe that the performance of this material has reached its limit , thus urging researchers to search. viable alternatives. One of the potential alternative materials focused by researchers is nano silicon but it is difficult to produce in large quantities and is often degraded very quickly.

Recently, researchers at the University of California, Riverside (UC Riverside) have overcome these problems by developing an anode for Li-ion batteries whose main components are sand.

UC Riverside's research stems from the discovery of Zachary Favors - a graduate student currently studying Li-ion batteries. During a trip to San Clemente, California, Favors realized that the sand he was lying on had a quartz or SiO ₂ main ingredient and this made him want to learn more about them. The research will help determine where sand in the United States may contain the highest percentage of quartz and eventually Favors found the right source of sand in the Cedar Creek reservoir area in Texas.

From left to (b) unrefined sand, (c) refined sand, (d) vials containing unrefined sand, refined sand and nano silicon

Favors collected a number of sand samples here and returned to the laboratory of Bourns School of Engineering at UC Riverside and here, he worked with engineering professors Cengiz and Mihri Ozkan. Favors began crushing sand to nano proportions before introducing them into a series of refining steps that made sand the same color and texture as powdered sugar.

Then, Favors put sand and magnesium into refined quartz and heated it into powder. In this simple process, sand acts as a heat-absorbing layer while magnesium removes oxygen from quartz, thereby producing pure silicon. Furthermore, pure nano-silicon is formed with very porous structure and consistently resembles 3-dimensional silicon. The porous state is one of the key to improving the performance of anode in a battery when it provides a larger surface, allowing Li + ions to pass through faster.

The team has successfully developed a coin-sized Li-ion battery that uses a new anode and they think its performance is significantly better than conventional Li-ion batteries. The group said the improved performance of silicon nanorods could increase battery life by up to three times when used on mobile devices such as phones, and the battery would only need to be fully charged every three days instead of daily as today. Similarly, Li-ion batteries with nano-silicon anodes will also extend the operation time of electric vehicles by 3 times, thereby cutting expensive replacement costs.

Researchers are now seeking to produce larger amounts of silicon nanoparticles and switch from circular batteries to larger batteries commonly used in mobile phones. UC Riverside's patent-pending technology and research details have also been published in Scientific Reports.