1. College of Chemistry and Chemical Engineering, Xi’an University of Science & Technology, Xi’an, China
2. Key Laboratory of Engineering Dielectrics and Its Application, Ministry of Education, University of Science and Technology, Harbin, China
3. College of Materials Science and Engineering, Xi’an University of Science & Technology, Xi’an, China
4. State Key Laboratory of Power System and Department of Electrical Engineering, Tsinghua University, Beijing, China