1. Faculty of Materials Science and Engineering Kunming University of Science and Technology Kunming 650093 P. R. China
2. Institute for Applied Materials (IAM) Karlsruhe Institute of Technology (KIT) Hermann-von-Helmholtz-Platz 1 Eggenstein-Leopoldshafen 76344 Germany
3. Faculty of Metallurgical and Energy Engineering Kunming University of Science and Technology Kunming 650093 P. R. China
4. Fraunhofer Institute for Solar Energy Systems Dep. Electrical Energy Storage Heidenhofstr.2 79110 Freiburg Germany
5. Freiburg Materials Research Center (FMF) Stefan-Meier-Straße 21 79104 Freiburg Germany
6. Institute for Sustainable Systems Engineering (INATECH) University of Freiburg Emmy-Noether-Straße 2 79110 Freiburg Germany