A new treatment that reduces the damage that occurs to silicon anodes upon charging has been developed. Lithium-ion batteries with silicon anodes have a higher charge density than conventional graphite anode batteries but are prone to degradation. This new treatment means silicon anode batteries will have a performance and service life that exceeds current standards.
Zhongwei Chen
These innovative silicon-based batteries could be used in a range of electronics from portable devices to electric cars.
The novel silicon battery developed by Chen’s team at the University of Waterloo is estimated to provide an increased energy density of 40% to 60%. The technology used has great green credentials as it is environmentally friendly and could also be used to enhance electric and hybrid vehicles.
The research revealed that the breakthrough technology could enable an electric car to be driven up to 500 km in between charges. Also, due to the increased energy density smaller and lighter batteries can be used, reducing the total weight of the vehicles.
Current lithium-ion use graphite anodes. Chen’s team decided to replace the graphite anodes with silicon anodes, as silicon possesses a superior capacity for lithium. Also, the batteries made with the silicon anode materials can hold 10 times more energy than their graphite based predecessors.
Graphite has long been used to build the negative electrodes in lithium-ion batteries. But as batteries improve, graphite is slowly becoming a performance bottleneck because of the limited amount of energy that it can store.
Prof. Chen - University of Waterloo
The Waterloo research team faced a serious challenge in the form of energy loss whilst producing the silicon-based batteries. Energy was lost due to the contraction and expansion of silicon, with a change in size of 300%, with every charge/decharge cycle. This continuous increase and decrease in volume resulted in the formation of cracks in the silicon. The cracks caused a deterioration in battery performance and the development of short circuits, which eventually result in the battery failing to function.
Chen’s team partnered with the Global Research and Development Centre at General Motors to find a viable solution to this issue. Together, they produced a flash heat treatment for the fabricated silicon-based lithium-ion electrodes. The treatment reduced the expansion of silicon which improved the lithium-ion batteries’ cycle capability and performance.
The economical flash heat treatment creates uniquely structured silicon anode materials that deliver extended cycle life to more than 2000 cycles with increased energy capacity of the battery.
Prof. Chen - University of Waterloo
Chen hopes that the technology will be commercialized and that a new range of batteries will hit the market by next year.
The Waterloo research was published in Nature Communications.