Preparation and characterization of the alternative binder for supercapacitor electrodes using the acid-catalyzed conversion of sugar

Binder is an additive used to promote cohesion and adhesion strength of a sheet of supercapacitor electrode. It allows an electrode to have good electronic conduction and energy storage performane. Typical binders are fluorinated polymer such as polytetrafluoroethylene (PTFE) and polyvinylidene difluoride (PVDF). In this work, we presented the environmentally friendly binder synthesized from sucrose and sulfuric acid which could replace fluorinated thermoplastic binders in electrochemical double-layer capacitor (EDLC) application. SH water-based binder contained sucrose/sulfuric acid at the weight ratio of 1:2 was cured at 120-350 °C. The binder wes characterized by water immersion, SEM, FTIR, XPS, TGA/DSC and electrochemical cyclic voltammetry. The SH binders showed good strength and electrochemical stability. The EDLC electrodes prepared from activated carbon (AC) composite containing 5 wt% of the SH precursor were assembled into a Swagelok symmetric test cell. The results showed that the SH electrodes had lower internal resistance than the PTFE electrodes, suggesting superior rate capability. The capacitive performance of the SH electrodes was comparable to the PTFE electrodes in the acid electrolyte. Specific capacitance values of the SH electrodes were around 125.35 ±4.18 F/g. In addition, the SCH electrode containing sucrose, CMC, and sulfuric acid displayed the higher specific capacitance of 132.80 ±15.31 F/g. The results of charge/discharge for 1000 cycles showed that the sucrose-based electrodes display good cycling stability. A slight difference in capacitance retention depended on electrolytes and electrode components