1. Inner Mongolia Enterprise Key Laboratory of High Voltage and Insulation Technology, Inner Mongolia Power Research Institute Branch, Inner Mongolia Power (Group) Co., Ltd., Hohhot 010020, China
2. College of Chemistry and Chemical Engineering, Inner Mongolia University, Hohhot 010021, China
3. Inner Mongolia Key Laboratory of Graphite and Graphene for Energy Storage and Coating, School of Materials Science and Engineering, Inner Mongolia University of Technology, Hohhot 010051, China
4. Inner Mongolia Institute of Metrology and Testing, Hohhot 010050, China