Binders from acid-catalyzed conversion of cellulose derivatives for supercapacitor application

The binder criterion for supercapacitors electrodes is the ability to provide good mechanical properties, chemical stability, and good electrical conductivity. These criteria are found in polytetrafluoroethylene (PTFE). However, PTFE is needed specific resources and production method that makes it expensive as well as less environmentally friendly. Industries and research institutes collaborate to research and develop alternative binders to fill the gap left by PTFE. In this work, we explain the alternative binder production via acid-catalyzed conversion of cellulose derivatives, the carbon electrode fabrication simultaneous with the transformation of cellulose into binders, and its characterization for application in supercapacitors technology. Hydroxypropyl methylcellulose (HPMC) and carboxymethyl cellulose (CMC) were used as binder precursors as well as p-toluenesulfonic acid (PTSA) as acid catalysts. Carbon electrodes with the HPMC Humins and CMC Humins-based binders, referred to as HPT and CPT respectively, were compared to PTFE electrode. Good electrode flexibility was achieved by adjusting the composition ratio and mass loading. However, SEM analysis showed slight cracks in the CPT electrode. HPT and CPT electrodes show good hydrophilicity than that of PTFE electrodes. Electrochemical characterizations of EDLC were carried out with a two-electrode cell configuration in H2SO4 and Na2SO4 electrolytes. Under a current density of 0.5 A/g in 1 M H2SO4, the capacitance values of HPT-160, CPT-160, and PTFE were 154 ± 16 F/g, 146 ± 13 F/g and 142 ± 9 F/g, respectively. Capacitance retention of HPT and CPT was better than that of PTFE after 1200 charge-discharge cycles. This research demonstrates that HPMC Humins and CMC Humins-based binders can outperform conventional binders, as well as the binder-electrode fabrication method offered is time saving, efficient and environmentally friendly.