Ionic liquid assisted fabrication of cellulose-based conductive films for Li-ion battery

摘要

An imidazolium-based ionic liquid, 1-ethyl-3-methylimidazolium diethyl phosphate ([Emim]DEP) was used to dispense graphene nanoplates (GN) and multiwalled carbon nanotubes (MWCNTs) as well as dissolve cellulose for fabricating composite conductive films. The effects of GN, MWCNTs, and cellulose mass ratios on the electrical conductivity and morphology of the films were investigated. The interaction between GN, MWCNTs, and cellulose was analyzed by SEM, X-ray diffraction (XRD), TGA, and Raman spectroscopy. The results indicate that [Emim]DEP plays a vital and irreplaceable role in GN and MWCNTs dispersion, cellulose dissolution, and porous formation during the regeneration and drying processes. MWCNTs linked flaky GN and a hybrid structure was constructed elaborately to form a better conductive path and improve the conductivity as well as increase the film stability. For the XRD result, the carbonized GN-MWCNTs-cellulose films exhibited the graphitic peaks, showing that the films still retained the structure of carbon atoms or molecules. Besides, the maximum conductivity of carbonized GN-MWCNTs-cellulose (7:3:2) composite film was up to 9,009 S m(-1), due to the small carbon clusters formation and the high degree of graphitization. Further, the carbonized films were applied as anodes in Li-ion battery and showed good electrochemical performance. The best cyclic stability (i.e., discharge/charge capacity) of 438/429 mA h g(-1) and coulomb efficiency of 50.2% were obtained. This novel and sustainable design is a promising approach to obtain cellulose-based conductive films and anodes for Li-ion battery applications.