New tech produces lighter, long-lasting batteries from silicon

Researchers have developed a new silicon-based anode that could pave the way for lighter and long-lasting lithium-ion batteries which could be used for everything from electronic devices to electric cars.
Researchers at the University of Waterloo, Canada, have developed a new type of silicon anode that boosts the performance and life of lithium-ion batteries.
The new silicon battery technology promises a 40 to 60 per cent increase in energy density, which is important for consumers with smartphones, smart homes and smart wearables, researchers said.
The technology could allow an electric car to be driven up to 500 kilometres between charges and the smaller, lighter batteries may significantly reduce the overall weight of vehicles.

Current lithium-ion batteries normally use graphite anodes. The Waterloo engineers found that silicon anode materials have a much higher capacity for lithium and are capable of producing batteries with almost 10 times more energy.
"Graphite has long been used to build the negative electrodes in lithium-ion batteries," said Zhongwei Chen, a chemical engineering professor at Waterloo.

"But as batteries improve, graphite is slowly becoming a performance bottleneck because of the limited amount of energy that it can store," Chen said.
The most critical challenge the researchers faced when they began producing batteries using silicon was the loss of energy that occurs when silicon contracts and then expands by as much as 300 per cent with each charge cycle.

The resulting increase and decrease in silicon volume forms cracks that reduce battery performance, create short circuits, and eventually cause the battery to stop operating.
To overcome this problem, Chen's team along with the General Motors Global Research and Development Centre developed a flash heat treatment for fabricated silicon-based lithium-ion electrodes that minimises volume expansion while boosting the performance and cycle capability of lithium-ion batteries.
"The economical flash heat treatment creates uniquely structured silicon anode materials that deliver extended cycle life to more than 2,000 cycles with increased energy capacity of the battery," said Chen.
Chen expects to commercialise this technology and to see new batteries on the market within the next year.

The advance was described in the journal Nature Communications.