1. Research Center of Grid Energy Storage and Battery Application, School of Electrical and Information Engineering, Zhengzhou University, Zhengzhou 450001, P.R. China
2. State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources, School of New Energy, North China Electric Power University, Beijing 102206, P.R. China
3. State Key Lab of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, P.R. China