Nitash Balsara, UC Berkeley

April 23, 2009 @ 9 am
Location: Carolyn Hoff Lynch Lecture Hall
Categories: Special Event

"Lithium Batteries in the Emerging Energy Landscape"

Abstract

There is a considerable need for developing batteries for emerging markets such as electric vehicles, renewable energy storage, and stabilizing the electric grid. These applications will require battery packs that store energy in the kWh to MWh range. A significant limitation of current batteries is that their specific energy, which is about 150 Wh/kg, is two orders of magnitude lower than that of fossil fuels. High specific energy lithium batteries exhibit explosive and unpredictable failure modes, making them unsuitable for large format applications. Many of these problems arise due to the presence of a volatile and flammable liquid electrolyte, and the inherent instability of the electrode-electrolyte interface. We demonstrate that replacing the electrolyte with a hard solid electrolyte holds promise for improving both specific energy and safety of lithium batteries. The electrolyte, obtained by self-assembly of block copolymer/salt mixtures, comprises soft conducting channels laced with lithium salts embedded in a hard insulating matrix. The width of the channels can be readily controlled in the 5-50 nm range. These electrolytes exhibit many surprising properties. In contrast to both current liquid and solid electrolytes, the ionic conductivity of the electrolyte increased with increasing molecular weight, thus enabling optimization of both its electrical and mechanical properties. Commercialization of batteries based on this invention is being pursued at a venture-backed start-up called Seeo.