In an effort to make longer-lasting, safer, and more affordable batteries, Washington-based XNRGI aims to build lithium batteries on plentiful, off-the shelf silicon wafers.
Last week, the company announced plans to bring new batteries based on its patented technology to market in 2020, in a new stationary storage battery.
Most such batteries today are used in commercial installations such as at utility transformer stations or at grid-scale power plants, especially for wind and solar.
XNRGI Powercell silicon wafer battery design (from company video)
Some, however, are used to store lower-cost electricity for electric-car DC fast-charging stations. Tesla and other companies also sell them for home installations, which can help EV owners use solar power to charge their cars.
XNRGI claims its new silicon-wafer Power Chip cells have four times the energy density of conventional lithium-ion cells and cost half as much.
Lithium batteries already use silicon anodes. XNRGI's technology, which has been in development for 15 years, imprints a 20-by-20 micron honeycomb onto commodity cells, then coats them with lithium and other materials to form the cathodes of millions of “microbatteries.” The company says the wafers can accommodate various lithium chemistries.
Using the silicon wafers solves several challenges, the company says. Each wafer structure, houses 36 million of these microbatteries on each 12-inch chip. The tiny active batteries carry a small enough charge and has enough space between cells to avoid the dendrite growth that causes traditional batteries to lose capacity over time, and eventually cause shorts that can lead to fires. XNRGI expects its batteries should last three times as long as conventional lithium batteries.
The company says the chips can safely be stacked to store up to 100 kilowatt-hours of electricity.
This resistance to dendrite growth can also reduce the need to slow down chargers when batteries get close to full. Today fast charging is measured in how fast a car can get to 80 percent of a charge, based on the power of the charger.
Tesla aside, the most powerful chargers—and the cars designed to accept the fastest charges—can operate at about 150 kilowatts, or an 80 percent charge in about 20 minutes. The quickest-charging cars coming in the next year will cut that time in half. That's still more than twice as long as it takes to fill up with gas. Speeding up that last 20 percent can go a long way toward making electric cars more competitive with gas.
XNRGI Powercell silicon wafer battery design (from company video)
XNRGI claims an energy density of 400 watt-hours per kilogram (1,600 watt-hours per liter) for its batteries, more than twice as much energy per pound as the best batteries on the road today.
The other benefit XNRGI claims for its cells is reduced cost. The company says it can build the cells for $150 per kilowatt hour, regardless of the application. It has already sold 600 of them for grid storage applications, but the company says they are just affordable for electronics.
Since the batteries can be made in existing silicon wafer plants, XNRGI claims the cost of a battery factory can be reduced by 95 percent.
The company has not revealed when its new battery format might be used for testing in cars themselves.
