Supercapacitors for Hybrid and Plug-in Hybrid Electric Vehicles V. R. Koch Covalent Associates, Inc. and Oregon State University December 4, 2008

Overview What are supercapacitors (aka EDLCs, ultracaps, supercaps)? Supercap market segments Ionic liquids: new electrolyte materials for high temp supercaps Supercap performance at elevated temps Summary Postscript from the Port of Yokahama

Types of Capacitors

Energy Storage Devices

Supercap Hardware AA size cell 2325 coin cell

Supercapacitor Test Bank

Fuji Heavy Industries (Subaru) has purchased the Electric Double Layer Capacitor (supercapacitor) business from Kanebo Ltd for an estimated 100 million yen, according to reports in the Japanese business press (August 2008). Fuji Heavy Industries plans to start commercial production of the ultracapacitor device before the end of 2010, and to sell the product to other companies, in addition to using it for its own vehicles. Why Supercaps for EV/PHEV?

EDLC Market Segments as f(T) -80 o C -60 o C -40 o C -20 o C 0oC0oC 20 o C 40 o C 60 o C 80 o C Military Auto Consumer electronics Available supercap thermal envelope: -30ºC to 65ºC

Supercaps for EV and PHEV Non-aqueous electrolytes fail at temps as low as 65ºC owing to thermal decomposition reactions. Supercap modules in hybrid EVs experience operating temps as high as 125ºC. New thermochemically stable electrolytes are required to enable supercap performance at elevated temps over long periods of time. Such electrolytes incorporate ionic liquid materials.

ILs are materials composed solely of anions and cations. Molecular solvents are composed of neutral species  benzene, propylene carbonate, water Ionic Liquids

Cation Structures

Inorganic Organic BR 4 - Sulfonate - O-(SO 2 R) PR 6 - Imide - N-(SO 2 R) 2 Methide - C-(SO 2 R) 3 Anion Structures R = halide, perfluoroalkyl and other electron withdrawing alkyl or aryl substituents

Critical Thermal Stability PC EMIIm No volatility High thermal stability bp 240ºC

Electrolyte Storage: 150 o C for 2 hr Ionic Liquid1M TEABF 4 /PC

Supercap Cycle Life: 150 o C at 1.75V Ionic Liquid 1M TEABF 4 /PC IL data represent 42 days of continuous cycling at 150ºC

Summary A new family of non-flammable and thermochemically stable ionic liquid electrolytes has been developed. Such electrolytes enable supercapacitor performance at temperatures in excess of 150ºC. We are working with device manufacturers to bring safe, high temperature supercaps to the auto industry.

PS from the Port of Yokahama