Enhancing Mechanical and Electrochemical Stability of EDLC Electrodes via Crosslinked Polysaccharide Binder Blends

Advancing sustainable energy storage technologies has increased the focus on water processable binders for high-performance battery and capacitor electrodes. In this work, a blend of potato starch (PS) and xanthan gum (XG) is chemically cross-linked with four carboxylic acids (citric, malic, succinic, and glutaric) to improve the mechanical and electrochemical performance of the electric double-layer capacitors (EDLCs) electrodes. Low-temperature cross-linking via esterification is confirmed by FTIR and TGA analysis, showing ester bond formation already at 80 °C. Mechanical characterization demonstrates that cross-linked binders, particularly citric acid (PXC) and malic acid (PXM), significantly improve adhesion strength (up to 0.38 MPa for PXC) and reduce elastic deformation, correlating with increased cross-linking density. Electrochemical tests demonstrate that PXC and PXM electrodes achieve superior capacitance retention at high current densities and long-term floating voltage conditions. After 500 h at 3 V, cross-linked electrodes retain over 91% of their initial capacitance, compared to 84% for the non-cross-linked reference. Electrochemical impedance spectroscopy further shows that cross-linked binders display notably lower contact and interfacial resistances, even after long term floating test. This study highlights the potential of cross-linked polysaccharide binders as a promising green binder system to enhance mechanical integrity and long-term high voltage electrochemical stability of EDLC electrodes.