Lithium-ion batteries have the highest specific energy of any rechargeable battery, which makes them promising candidates for use in electric and hybrid vehicles. However, accidental overcharge of a lithium-ion cell can cause severe degradation of the cell components and can risk fire or even explosion. Vehicle applications require large batteries comprised of many cells connected in series. Since it is impossible to maintain every cell in a series-connected string at exactly the same capacity, large batteries will require mechanisms to protect each cell in a string from overcharge.Tom Richardson and Guoying Chen at LBNL are developing a new mechanism for overcharge protection that involves using electroactive polymers such as polythiophene. These polymers are insulators at moderately reducing potentials but become electronically conductive when oxidized. Karen Thomas will discuss her recent work using continuum-scale computer simulations to elucidate what happens to the polythiophene when the battery is overcharged and to evaluate design options.Dr. Thomas received her B.S.E. in environmental engineering from Princeton University and her Ph.D. in chemical engineering from U.C. Berkeley. She is presently a post-doc with Professor John Newman at LBNL.