Making Silicon Anodes ViableCategory: Science & Technology
Posted: November 6, 2012 08:00AM
Lithium-ion batteries are among the most common, if not the most common variety of rechargeable batteries used for electronics. From cellphones to electric cars these batteries power technology, but have several limits on their capabilities. Researchers at Rice University though have found a way to push back those limits with crushed porous silicon anodes.
For some time researchers have known that silicon could replace graphite at the anodes of lithium batteries to increase their power, but at a dangerous cost. When silicon absorbs the lithium ions, it expands and can expand so much that a solid anode could break apart and damage the battery. Some have tried putting pours into the silicon to accommodate the expansion, but the Rice researchers have changed that approach slightly by crushing up the porous silicon, instead of leaving it as a film or sponge. The result is a powder with 50 times more surface area for absorbing silicon, but enough void space to not break apart. When tested in half-batteries, the researchers have achieved 1,000 milliamp hours per gram, which is some three times greater than the previous record, with 600 charge/discharge cycles.
As impressive as that 1000 mAh/g figure is, it could be just a third of what crushed porous silicon is capable of. Once it is further improved though, it may be able to reach consumer products relatively quickly, thanks to it being easy and cheap to produce.