Graphene shell to protect silicon anode

Now that masks made with its patented ZENGuard antimicrobial graphene coating are being commercially produced, Zentek Ltd. is looking at other ways to leverage the superlative qualities of the graphene it produces to make the world a better place. This includes research into making better lithium batteries with graphene-coated silicon as the anode.

As an anode material, silicon has shown the ability to have up to 10 times more storage capacity than the graphite that is currently the material primarily used for this purpose. Silicon, however, has one major drawback – when charged, it swells more than three times and becomes unstable.

Given the potential battery performance enhancements that could be achieved with silicon anodes, researchers have been looking at ways to overcome the swelling and instability issues.

With research and development funding from Zentek and others, Professor Michael Pope at the University of Waterloo in Ontario, Canada, is working on one such solution that involves graphene-coated silicon anode.

Pope and his research team have developed a method of applying a protective graphene coating to high-capacity silicon anode material that is reminiscent of candies with a hard shell that allows the chocolate to melt in your mouth and not in your hands.

"Our lab, through ongoing efforts supported by Zentek and the Natural Sciences and Engineering Research Council of Canada, has developed an improved method to enable high capacity, high cycle-life anodes by encapsulating them in a protective, crumpled graphene shell using a simple spray drying approach often used to generate much of the world's dry powders," said Pope.

With further testing and development, this graphene-coated silicon could offer an alternative to the spherical coated graphite that is used as the anode material in most of today's lithium batteries.

In preliminary testing, the graphene-wrapped silicon anode retained 79% of its capacity after 200 charge-discharge cycles when paired with half-cells, a battery electrode configuration used for laboratory testing.

When paired with a commercial lithium iron phosphate cathode, a lower-cost battery that is becoming popular for powering electric vehicles, the fully assembled battery retained 93.3% of its initial capacity over 100 cycles.

"Not only were the researchers able to demonstrate good performance with laboratory-scale half-cells, the performance was also validated with commercial lithium iron phosphate cathodes suggesting they could be a drop-in solution for enhancing already available battery technologies," said Zentek CEO Greg Fenton.

While this graphene-coated silicon anode technology requires further development and optimization work before it is ready for commercialization, Zentek and Professor Pope's team of researchers at Waterloo are encouraged by these initial results and plan to continue work on this promising lithium battery technology.

"We look forward to our continued collaboration with Zentek which we hope will soon lead to a dominant, commercial anode technology," said Pope.

Given the promising results, Zentek has also filed a provisional patent with the United States Patent and Trademark Office on the novel graphene-wrapped silicon anode material being developed.

"We look forward to continuing our support of their research and development to potentially bring this technology to market," said Fenton. "The company has begun discussions with a potential industry partner."

A paper on graphene-wrapped silicon anode technology co-authored by Zimin She, Marianna Uceda, and Pope was published in ACS Applied Materials & Interfaces on Feb. 17 and can be read at https://pubs.acs.org/doi/10.1021/acsami.1c23356.

Author Bio

Shane Lasley, Metal Tech News

With more than 16 years of covering mining, Shane is renowned for his insights and and in-depth analysis of mining, mineral exploration and technology metals.

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