Highly conductive Poly(ε-caprolactone) and chitosan based polymer electrolyte for lithium metal battery

Poly (ε-caprolactone) (PCL) is an attractive polymer electrolyte material due to its ultralow glass transition temperature, high dielectric constant as well as excellent electrochemical stability, but its practical application has been greatly hindered due to the low ionic conductivity induced by the semi-crystalline structure. Herein, we elaborately modify PCL with chitosan (CS) to obtain an amorphous PCL-CS composite membrane, and develop a fast Li + conducting quasi-solid polymer electrolyte (QPE) with lithium bis(trifluoro methane sulphonyl)imide (LiTFSI) and merely 10 wt% plasticizer. The optimized QPE with 50 wt% LiTFSI exhibits an ionic conductivity of 7.7 × 10 −4 S cm −1 , which is the highest among PCL-based polymer electrolyte. Fourier Transform Infrared spectroscopy and Raman spectra reveal that Li + conducting via the solvation of partial plasticizer as well as contacted ionic clusters. In addition, its excellent stability and compatibility are validated by the integrated symmetric Li//Li cell that exhibits an ultra-long cycling for over 1850 h with no Li dendrite formation. • A totally amorphous polymer framework has been designed. • A higher ionic conductivity than reported PCL based polymer electrolyte. • Li ion is efficiently conducted via dual pathways.