February 6, 2013

Startup Seeo Creates Safer Next-Gen Lithium Battery

The unnerving capability of lithium ion batteries to catch on fire emerged as headline news last month, as Boeing was forced to ground its futuristic 787 Dreamliner FLEET after two batteries caught on fire. But the next generation of lithium ion batteries are promising to be safer, and a few of them are already starting to be used in real-world situations in the power grid, electric vehicles and gadgets.

Six-year-old startup Seeo — which is backed by Vinod Khosla, Google Ventures and others — has installed its first battery system to act as energy storage in conjunction with a solar panel system developed by SunEdison, according to Seeo CEO Hal Zarem, who I interviewed last week. The solar battery installation is a trial for now, but a sizable one: on the level of kilowatts and tens of kilowatts, explained Zarem. For comparison’s sake, the Nissan LEAF uses a 24 kilowatt hour battery, while an average cell phone will use 2,000 to 3,000 milliamp hour batteries (far smaller than a kilowatt hour of capacity).

Batteries, like the one Seeo has installed for SunEdison’s solar system, can act as storage for the energy produced by solar panels, so that when the sun goes down (or behind a cloud) the battery can then offer up the stored power. Utilities, building owners and even home owners are starting to see the benefits of having battery storage systems connected to solar systems, because power can be far more smooth and reliable. Likewise solar installer SolarCity has been working with Tesla’s batteries to sell a home battery system with its solar panels in certain markets.


So what makes SolarCity s batteries safer? It largely involves improvements to the electrolyte, or the medium that shuttles lithium ions back and forth between the cathode and the anode to charge and discharge the battery. Traditional lithium-ion battery electrolytes are mostly made of liquids, while Seeo is using a solid dry polymer based electrolyte, which feels like plastic to the touch.

The polymer is non-flammable and when combined with using lithium foil as the anode, the battery can be ultra light weight and also have a high energy density, or amount of energy that can be stored per a given weight. During an interview at Seeo’s headquarters last week I picked up and compared two battery packs — one made by Seeo, and one that used traditional lithium ion batteries — and the Seeo battery felt about three times lighter.

If traditional lithium ion batteries are overcharged they can have a margin of error in the danger zone of about 20 percent above the max voltage of the battery, explained Zarem. In contrast, Seeo batteries have a margin of error of 100 percent over the voltage. The batteries also won’t burst into flames if something penetrates it (for example, during a car crash).

Seeo isn’t the only one working on solid electrolytes for batteries. It’s actually a growing field for innovation, and startups like Sakti3, and Imprint Energy are working on this technology, as are researchers at Oak Ridge National Laboratory.
by Katie Fehrenbacher

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