A novel composite electrolyte membrane (CEM), consisting of a viscous PEGMEM-co-SMA copolymer, lithium salt and cellulose matrix, has been prepared as a new class of electrolyte for high performance lithium-ion batteries (LIBs). This CEM exhibits a wide electrochemical stability window (> 5 V vs. Li/Li+), reasonably high ionic conductivity and thermal stability up to 315 degrees C. At temperature above the melting temperature (31.98-35.71 degrees C), the viscous flow nature of the copolymer is beneficial to fully infiltrate the electrode materials like liquid electrolyte to maintain uniform contact with electrode surfaces during charge/discharge process. The interfacial resistance (R-intf) of the fresh cell based on this CEM is extremely low (3.8 Omega cm(-2)) and the Li/LiFePO4 cell deliveries a discharge capacity as high as 156.9 mA h g(-1) with a current density of 1 C at 80 degrees C. It is anticipated that this work provides a new insight for designing advanced electrolyte materials for LIBs with enhanced interfacial contact and excellent cycling performance. (C) 2015 Elsevier B.V. All rights reserved.