Electric car range could triple with silicon-graphene breakthrough in lithium batteries
Energy density is the key measure of electric car batteries to determine driving range and ultimately the usefulness of the vehicle. It was the energy density improvements of lithium-ion batteries that enabled the resurgence of electric cars. But the current crop of lithium ion batteries do not allow for enough energy storage, and driving range, at a low enough cost, to get past the "too expensive" sniff test that is hindering electric car adoption today. A new lithium-ion battery designed by CalBattery, with a silicon-graphene anode, promises a dramatic energy density breakthrough, according to a news release issued by the company on Friday.
The company is a finalist in the Dept of Energy's 2012 Start UP America's Next Top Energy Innovator challenge. Independent test results using full-cell lithium-ion battery cells designed by CalBattery demonstrate an energy density of 525 watt-hours per kilogram, and a specific anode capacity of 1,250 mili-amp-hours per gram. Most commercial batteries have an energy density in the 100-180 watt-hours per kilogram range, and specific anode capacity in the 325 mili-amp-hours per gram range.
For those who don't understand battery capacity measurements, this means that per kilogram of battery weight a battery pack made with CalBattery cells will store 300% more energy than current batteries.
For the same battery pack weight this means the ability to drive 300% as far as with current electric cars, or to have the same driving range as today the battery pack would be about 1/3rd the weight.
"This equates to more than a 300% improvement in lithium-ion battery capacity, and an estimated 70% reduction in lifetime cost for batteries used in consumer electronics, EVs, and grid-scale energy storage," said CalBattery CEO Phil Roberts.
This is based on what the company has dubbed the "GEN3" silicon-graphene composite anode material for lithium-ion batteries. The key to the GEN3 design is use of a breakthrough developed at Argonne National Labs that stabilizes the use of silicon in a lithium battery anode. Silicon is known to absorb lithium better than any other anode material, it quickly deteriorates during use. CalBattery has worked closely with researchers at Argonne and other facilities to develop the new anode material, to integrate it in lithium-ion batteries having multiple cathode and electrolyte materials.
The anode is the electrode by which the electrons leave a battery into the device, while the cathode is the electrode through which electrons return to the battery, and the electrolyte is the material between anode and cathode through which lithium ions move. In other words, the anode is the negative terminal of the battery, and the cathode is the positive terminal.