Silicon Nanopores Pack More Punch Into Batteries
Researchers at Rice University have found a way of using silicon to boost the capacity of lithium-ion batteries by a factor of 10. The discovery could increase the performance of the batteries in everything from laptops to electric vehicles.
The technique provides a more effective way of using silicon as the anode, or negative, side of a lithium-ion battery. Batteries now use graphite anodes, which work well. “But it’s maxed out,” said Michael Wong, a professor of chemical and biomolecular engineering and of chemistry. “You can’t stuff any more lithium into graphite than we already have.”
Nothing holds lithium quite like silicon, which has the highest theoretical capacity for storing the stuff. “It can sop up a lot of lithium, about 10 times more than carbon, which seems fantastic,” Wong said. “But after a couple of cycles of swelling and shrinking, it’s going to crack.”
Others have tried using silicon nanowires, which work a bit like a mop to sop up lithium. The Rice University researchers, joined by scientists from Lockheed Martin, thought a sponge might work better.
They found that micron-sized pores in the surface of the silicon wafer (shown above) gave it plenty of room to expand. While common li-ion batteries hold about 300 milliamp hours per gram of carbon-based anode material, the treated silicon could, in theory, hold 10 times that much.
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