Dielectric behavior and proton conductivity of ultrasound-assisted graphene oxide/sulfonated poly(ether ether ketone) composite electrolytes

Abstract

This work deals with the evaluation of proton conductivity and dielectric measurements of graphene oxide (GO) doped sulfonated poly(ether ether ketone) (SPEEK) electrolytes for electrochemical devices. SPEEK-GO composite electrolytes were successfully prepared via ultrasound-assisted solution casting method. FTIR, SEM, and TGA analysis were performed to characterize the GO, SPEEK matrix, and current SPEEK-GO electrolytes. Additionally, the effects of GO loading on the proton conductivity and the dielectric behavior were also studied. The effectiveness of the oxy-groups in the GO structure for proton conduction via the Grotthus mechanism was demonstrated, and the SPEEK-GO-(10.0) composite electrolyte had the highest observed proton conductivity value of 4.79 × 10−3 S/cm. This value is roughly four times greater than the proton conductivity value of the pure SPEEK polymer matrix under the same conditions (400 K, 1 MHz), which is 1.23 × 10−3 S/cm. GO was able to increase the dielectric constant (ε′) both through its large surface area and aspect ratio and through its polar functional groups, which can interact with the SPEEK polymer matrix. The decrease in the electric modulus (M′) of the SPEEK-GO-(10.0) composite with increasing temperature could be attributed to both the decrease in the complex modulus and the formation of voids and gap at the interface between the polymer matrix and the GO particles.