The improved effect of co-doping with nano-SiO2 and nano-Al2O3 on the performance of poly(methyl methacrylate-acrylonitrile-ethyl acrylate) based gel polymer electrolyte for lithium ion batteries

In this article, we report a novel gel polymer electrolyte (GPE) for lithium ion batteries, which is prepared using poly(methyl methacrylate-acrylonitrile-ethyl acrylate) (P(MMA-AN-EA)) as a polymer matrix and doping with nano-SiO 2 and nano-Al 2 O 3 simultaneously. The influences of the ratio of the two nanoparticles on the pore structure, electrolyte uptake and thermal stability of the resulting membrane, and the ionic conductivity and electrochemical stability of the corresponding GPE are investigated by scanning electron microscopy, mechanical strength, thermogravimetry, electrochemical impedance spectroscopy, linear sweep voltammetry and cyclic voltammetry. The performance of the developed GPE is evaluated in the Li/LiNi 0.5 Mn 1.5 O 4 half cell by a charge-discharge test for its application in lithium ion batteries. It is found that there exists a synergistic effect between nano-SiO 2 and nano-Al 2 O 3 . The performances of the resulting membrane and the corresponding GPE are effectively improved by using nano-SiO 2 and nano-Al 2 O 3 simultaneously rather than individually. Co-doping 5 wt% nano-SiO 2 and 5 wt% nano-Al 2 O 3 provides the membrane with a higher thermal decomposition temperature of 325 °C, and a better electrolyte uptake of 198.1%, the corresponding GPE with an increased ionic conductivity of 2.2 × 10 −3 S cm −1 at room temperature and an enhanced oxidative stability up to 5.5 V ( vs. Li/Li + ), and the LiNi 0.5 Mn 1.5 O 4 cathode with an improved rate capability of 104.2 mA h g −1 at 2C and an improved capacity retention of 94.8% after 100 cycles. These improved performances result from combining the advantages of both nano-SiO 2 and nano-Al 2 O 3 , in which the former contributes to the improved ionic conductivity caused by a stronger Lewis-acid property, while the latter to the better thermal and structural stabilities by its stiffness characteristic. We report a novel gel polymer electrolyte (GPE) for lithium ion batteries, which is prepared using P(MMA-AN-EA) as a polymer matrix and doping with nano-SiO 2 and nano-Al 2 O 3 simultaneously.