1. Beijing Key Laboratory of Environmental Science and EngineeringSchool of Materials Science and EngineeringBeijing Institute of Technology Beijing 100081 P. R. China
2. Key Laboratory for Renewable EnergyBeijing Key Laboratory for New Energy Materials and DevicesInstitute of PhysicsChinese Academy of Sciences Beijing 100190 P. R. China
3. Key Laboratory of Materials Processing and MoldMinistry of EducationZhengzhou University Zhengzhou 450002 P. R. China
4. Collaborative Innovation Center of Electric Vehicles in Beijing Beijing 100081 P. R. China