Recent advances in and perspectives on binder materials for supercapacitors–A review

The development of electrode materials, electrolytes, and separators for energy-storage devices has received a great deal of attention. To meet the essential requirements of cutting-edge technologies, including electric vehicles, tremendous effort has been made to develop efficient energy storage device components. Unfortunately, binders have not gotten the same attention despite being crucial to energy-storage devices. Polyvinylidene fluoride (PVDF) has always been the preferred binder in the supercapacitor business. However, PVDF has some limitations, such as low electrical conductivity (10-2 Sm−1), insufficient mechanical characteristics, and limited binding strength. In conventional electrodes, the binder is often electrochemically inert, with weak contacts and interfaces between the binder and the active material, which increases "dead mass" and has a direct impact on the performance of the energy storage system. The binder-free electrode is a good contender for addressing the challenges mentioned above. Additionally, to achieve higher sustainability, the notion of green binders has been established using three alternative interpretations, namely (i) processability, (ii) chemical composition, and (iii) natural availability. This review article includes the details of existing and emerging binders in supercapacitors. We included the progress towards the greenness of binder materials and, finally, the advancements of binder-free electrodes.