A company founded in a Palo Alto public library has created a new silicon carbon battery that carries roughly twice as much energy per gram as current batteries, opening up the road to long distance electric cars to drive up to 300 miles on a single charge.
Envia System creates lithium-ion battery packs that produce 400-watt-hours per kilogram, validated by independent energy density tests at the Naval Surface Warfare Center in Crane, Ind.
“We have made a 40 ampere cell in a large format that automakers can recognize and use,” Sujeet Kumar, the company’s co-founder and CTO told Scientific American.
The company implemented research from work done at the Argonne National Laboratory that used maganese in a mix of materials for a cathode (the electrode to which lithium ions gather) to create stronger energy densities. Envia focused on the anode, the electrode from which lithium ions flow to create electric current, and incorporated silicon along with the standard graphite to dramatically increase performance. The blend of silicon with carbon alleviates the problem that most silicon anodes have in keeping a charge. Silicon swells, but encasing it in the carbon and interlacing fibers circumvents this problem. Envia’s battery has been cycled 400 times and counting.
The technology also addresses the “thermal runway,” engineering talk for when a battery bursts into flames, problematic in energy dense storage devices incorporating lithium-ions. Batteries are typically subjected to an 8-millimeter nail penetration test, which the company claims to have passed.
“It’s mainly that the cells are much thinner,” Kumar told Scientific American. “It’s very easy to remove the heat.”
At $125 per kilowatt hour, the batteries are cheap at less than half of what current batteries cost, which typically contribute to 65 percent of the cost of an electric car. If the batteries stand up to further tests, they could enable a Nissan LEAF to travel 300 miles on a single charge, compared to the current 80 mils per charge the vehicles deliver today. Envia’s batteries could enable electrical cars to actually be practical, getting their owners everywhere they’d have to go in a single day without needing plugged in.
The company has GM as an investor, but has declined to state which car companies it is actually working with to implement the technology.
“We expect Envia’s next generation lithium-ion battery will revolutionize the [electric vehicle] industry by eliminating the three remaining barriers to mass adoption: cost, range and safety,” Kumar said in a statement announcing the breakthrough. “The ability to drive up to 300 miles on a single charge will eliminate ‘range anxiety.'”