High electrochemical performances of solid nano-composite star polymer electrolytes enhanced by different carbon nanomaterials

Abstract

Here, two type of composite star polymer electrolytes enhanced by carbon nano-tube (CNT) or fullerene (C60) prepared through a solution-casting technique are investigated. The as-prepared free-standing carbon nano-composite polymer electrolyte membranes exhibit excellent comprehensive performances including high thermal stability (initial thermal degradation temperatures about 383 °C) and good electrochemical properties. However, different carbon nanomaterials bring different influence on electrochemical performances of composite polymer electrolytes. The ionic conductivity of carbon nanotube composite polymer electrolyte (HBPS-(PMMA-b-PPEGMA)30/CNT/LiTFSI) is higher than that of fullerene composite polymer electrolyte. The highest ionic conductivity of HBPS-(PMMA-b-PPEGMA)30/CNT/LiTFSI electrolyte can reach 1.06 × 10−5 S cm−1 at 30 °C and lithium-ion transference number reaches 0.52. In addition, two types of carbon nano-composite star polymer electrolytes both exhibit wide electrochemical window with oxidation potential above 5.2 V, good interfacial stability and interfacial compatibility. Moreover, assembled Li/LiFePO4 cells based on HBPS-(PMMA-b-PPEGMA)30/CNT/LiTFSI electrolytes possess good specific capacity with the highest value of 133 mAhh g−1, while the cells based on HBPS-(PMMA-b-PPEGMA)30/C60/LiTFSI electrolytes show a great cycle stability.