Natural Polymers as Green Binders for High Loading Supercapacitor Electrodes.

The state of the art aqueous binder for supercapacitors is carboxymethyl cellulose (CMC). However, it limits the mass loading of the coatings due to shrinkage upon drying. In this work, natural polymers, i.e., guar gum (GG), wheat starch (WS), and potato starch (PS), are studied as alternatives. Flexibility and adhesion of the resulting coatings and electrochemical performance is tested. The combination of 75:25 (w/w) ratio PS:GG shows promising performance. Electrodes are characterized via SEM, thermal, adhesion and bending tests. Their electrochemical properties are determined via cyclic voltammetry, EIS, and cycling experiments. The PS:GG mixture conforms well to criteria for industrial production enabling mass loadings higher than CMC (7.0 mg cm -2 ), while granting the same specific capacitance (26 F g -1 ) and power performance (20 F g -1 @ 10 A g -1 ). Including the mass of the current collector, this represents a +45% increase in specific energy at the electrode level.