Electrochimica Acta, Vol.267, 213-221, 2018
Effect of polymer binders on graphene-based free-standing electrodes for supercapacitors
As the rapid growth of supercapacitor industry, there are increasing demands for aqueous dispersible and environmentally friendly polymer binders to manufacture graphene electrodes with high capacitance, long lifetime, and great mechanical flexibility. Here, four different binders were selected to study the effect on structural and electrochemical performance of the reduced graphene oxide (rGO) thin film electrodes. The four binders include two fluorinated polymers, a conductive binder formulation, and a water-based elastomeric binder. The morphology, crystallinity, thermal stability, and hydrophilicity of the electrode films were characterized. Electrochemical measurements were carried out to compare capacitance, resistance, and frequency response of the electrodes with various binders. Results reveal that the rGO with conductive binders showed the highest capacitance with low internal resistance in both aqueous and organic electrolytes; while the rGO bound by elastomeric binder exhibited excellent cycling stability, low charge transfer resistance, and low relaxation time constant in aqueous electrolyte. Moreover, it was found that that binders with high conductivity and enhanced compatibility with electrolytes can facilitate ionic diffusion within the porous structure of electrodes, which leads to faster frequency response and better capacitive properties. (C) 2018 Published by Elsevier Ltd.