Performance of metal oxide nanoparticle sols as binders in activated carbon electrodes

• SiO2 and AlOOH functioned as a binder in preparing activated carbon-based electrodes.
• The composites with metal oxides improved the physical stability of electrodes.
• Addition of metal oxides raised the electrochemical capacitance from 15 to 69 F g−1.

The primary purpose of this study was to evaluate the performance of composites, as electrode materials, made with activated carbon (AC) and SiO2 or γ-AlOOH gels as binders and compare these to traditional electrodes fabricated with AC and polyvinylidene fluoride (PVDF). Electrodes made out of AC and SiO2 or γ-AlOOH composites showed a much better wear resistance than those fabricated with AC and PVDF composites. Furthermore, cyclic voltammetry and chronopotentiometric measurements showed that the electrodes using oxides as binders had an electrochemical capacitance between 2 and 5 times higher than those made with AC and PVDF composites. This higher electrochemical capacitance is based on the fact that composites that use SiO2 and γ-AlOOH as binders exhibit a much higher specific surface area and water hydrophilicity than those containing PVDF. The addition of PVDF to the AC decreases its specific surface area by a factor of seven. In contrast, the addition of SiO2 or γ-AlOOH gels to the AC powder slightly increases the surface area. Scanning electron microscopy (SEM) images showed that the AC particles are coated with a nanoporous layer of these metal oxides.