1. School of Materials and Energy, Guangdong University of Technology, Guangzhou 510006, China
2. Guangxi Key Laboratory of Automobile Components and Vehicle Technology, Guangxi University of Science & Technology, Liuzhou 545006, P. R. China
3. National Engineering Laboratory for Modern Materials Surface Engineering Technology, Guangdong Institute of New Materials, Guangdong Academy of Science, Guangzhou 510650, P. R. China
4. Dongfeng Xiaokang Moto Co., Ltd, Shiyan 442000, P. R. China
5. College of Smart Energy, Shanghai Jiao Tong University, Shanghai 200240, P. R. China