1. Guangdong Provincial Key Laboratory of Quantum Engineering and Quantum Materials; School of Physics and Telecommunication Engineering; South China Normal University; Guangzhou 510006 PR China
2. Guangdong Engineering Technology Research Center of Efficient, Green Energy and Environmental Protection Materials; South China Normal University; Guangzhou 510006 PR China
3. Engineering Research Center of Materials and Technology for Electrochemical Energy Storage (Ministry of Education); Guangzhou 510006 PR China
4. Department of Physics; University of Hong KongPokfulam Road; Hong Kong P.R. China