Chloroaluminate-Doped Conducting Polymers as Positive Electrodes in Rechargeable Aluminum Batteries

Abstract

Demonstrated here is the use of conducting polymers as active materials in the positive electrodes of rechargeable aluminum-based batteries operating at room temperature. The battery chemistry is based on chloroaluminate ionic liquid electrolytes, which allow reversible stripping and plating of aluminum metal at the negative electrode. Characterization of electrochemically synthesized polypyrrole films revealed doping of the polymers with chloroaluminate anions. Cycling of the conducting polymer electrodes occurred via the electrochemical insertion and removal of these anions. Stable galvanostatic cycling of polypyrrole and polythiophene cells was demonstrated, with electrode capacities at near-theoretical levels (30–100 mAh g –1 ) and Coulombic efficiencies approaching 100%. The energy density of a sealed sandwich-type cell with polythiophene at the positive electrode was estimated to be 44 Wh kg –1 relative to the total mass of active components. This energy density is competitive with state-of-the-art battery chemistries for grid-scale energy storage.