[1] Paul Scherrer Inst, Electrochem Lab, CH-5232 Villigen, Switzerland
[2] Graz Univ Technol, Inst Chem Technol Inorgan Mat, A-8010 Graz, Austria
[3] Electrochem Energy Storage & Convers, ZSW Ctr Solar Energy & Hydrogen Res Baden Wuertte, Div 3, D-89081 Ulm, Germany
[4] Rhein Westfal TH Aachen, Inst Power Elect & Elect Dr, D-52066 Aachen, Germany