International. Scientists have been trying for years to make a handy lithium-ion battery with silicon anode, which could store 10 times more energy per charge than today's commercial anodes and make high-performance batteries much smaller and lighter.
However, two main problems have gotten in the way: silicon particles swell, crack and break during battery charging, and react with the battery's electrolyte to form a coating that depletes its performance.
Now, a team from Stanford University and the Department of Energy SLAC National Accelerator Laboratory, has come up with a possible solution: Wrap every silicon anode particle in a custom box made of graphene, a pure form of carbon, the thinnest and strongest material known and a great conductor of electricity.
In one report, they describe a simple three-step method for building microscopic graphene cages of just the right size: wide enough to allow the silicon particle to expand while charging the battery, but tight enough to hold all the pieces together when the particles fall, so it can continue to operate at high capacity. Safes and flexible safes also block destructive chemical reactions with the electrolyte.
"In testing, graphene boxes actually improve the electrical conductivity of the particles and provide high carrying capacity, chemical stability and efficiency," said Yi Cui, an associate professor at SLAC and at Stanford who led the research. The method can be applied to other electrode materials, too, making low-cost, energy-dense battery materials a reality possibility."
