1. State Key Laboratory of Polymer Materials Engineering Polymer Research Institute Sichuan University Chengdu 610065 P. R. China
2. Institute of New Energy and Low‐Carbon Technology Sichuan University Chengdu 610065 P. R. China
3. ISIS Neutron and Muon Source, Science and Technology Facilities Council, Rutherford Appleton Laboratory Harwell Campus OXON Didcot OX11 0QX UK
4. State Key laboratory of Environment‐Friendly Energy Materials, School of Materials and Chemistry Southwest University of Science and Technology Mianyang 621010 P. R. China