1. Centre for Cooperative Research on Alternative Energies (CIC energiGUNE), Basque Research and Technology Alliance (BRTA), Alava Technology Park, Albert Einstein 48, 01510 Vitoria-Gasteiz, Spain
2. University of the Basque Country (UPV/EHU), Barrio Sarriena, s/n, 48940 Leioa, Spain
3. Saft, 111 Boulevard Alfred Daney, 33074 Bordeaux Cedex, France
4. Institute for Frontier Materials, Deakin University, Geelong, Victoria 3217, Australia