Every electronic device needs power. For many of those gadgets, like phones, laptops or tablets, the power is stored in a battery. But what if power storage was integrated directly into the device? No battery required?
For the first time, scientists have created a power cell out of silicon — the same material used to make computer chips and solar cells — and the development could lead to devices capable of storing their own energy without batteries. The so-called silicon supercapacitor would charge within seconds and deliver power to mobile phones for days on end. It could also be etched into the back of silicon wafers used to make solar cells, allowing solar panels to generate and store electricity in one package.
Capacitors differ from batteries in that they store electrons on a surface rather than in a chemical reaction. They can be recharged thousands of times more often than a battery and absorb power faster.
“If you ask experts about making a supercapacitor out of silicon, they will tell you it is a crazy idea,” said assistant professor of mechanical engineering Cary Pint in a press release. Pint headed the research at Vanderbilt University.
Most high-end capacitors, called supercapacitors, are made of carbon, not silicon. Silicon reacts easily with other materials, including gases in the air. But silicon would be a better material than carbon, because silicon is used so much in the electronics industry.
Pint and his colleagues decided they wanted to make silicon work. So they coated a piece of it in carbon to protect it from reacting with other chemicals and then heated it in a furnace to seal the coating. That’s when an unexpected development occurred: the coated carbon turned into a nanometer-thick layer of graphene. Just that thin layer of graphene boosted the amount of energy the capacitor could store by a factor of 100.
Even though the Vanderbilt capacitor was better than almost any other currently on the market it was not as energy-dense as a battery. There is still more work to be done. But by it’s a big step to demonstrate that this energy storage works in silicon because once improved, it could easily be incorporated into the chip-manufacturing process.