Hydroxypropyl cellulose as fluorine-free alternative binder for aqueous supercapacitors

The development of sustainable energy storage devices, such as supercapacitors (SCs), pushes towards innovative material science solutions. This study presents Hydroxypropyl Cellulose (HPC) as a promising fluorine-free binder (FFB) alternative to traditional fluorinated binders exploited in aqueous-based electrolytic systems. HPC offers water solubility and pH stability, making it an environmentally friendly option for aqueous electrolyte-based SCs. We investigated HPC’s efficacy as a binder in activated carbon-based SC electrodes due to its salt out effect, comparing it with conventional Polyvinylidene Fluoride (PVDF) binder. Electrodes were tested in acidic (1 N H2SO4), neutral (1 N Na2SO4), and basic (1 N KOH) electrolytes, with titanium current collectors. Our findings reveal that HPC-based electrodes exhibit superior uniformity and interconnectivity, as evidenced by electron microscopy and surface area measurements. Electrochemical characterizations demonstrate that HPC electrodes outperform PVDF counterparts in all tested electrolytes, particularly in terms of chemical stability in basic solutions where PVDF degrades. The HPC devices achieved specific capacitances of 22.21 F g− 1 (acidic), 17.03 F g− 1 (neutral), and 23.86 F g− 1 (basic) with over 90 % retention after 10,000 charge-discharge cycles and 160 h of floating tests. These results suggest that HPC not only ensures environmental safety but also enhances performance and durability across various pH environments. In conclusion, HPC proved to be a sustainable and effective binder for electrochemical systems with both capacitive and faradic electrodes. Future research should focus on integrating HPC with more stable current collectors to further improve devices’ performance, especially in acidic media, seawater and wastewater, thus advancing the field of eco-friendly energy storage technologies.