1. School of Materials and Energy, University of Electronic Science and Technology of China, Chengdu, 611731, P. R. China
2. Wuhan Institute of Marine Electric Propulsion, Wuhan 430064, P. R. China
3. School of Mechanical Engineering, Sichuan University, Chengdu 610065, P. R. China
4. China Automotive Engineering Research Institute Co., Ltd., Chongqing 401122, P. R. China