Flexible Supercapacitors Based on Solid Ion Conducting Polymer with High Mechanical Strength

Mechanical strength is crucial to flexible supercapacitors during their practical usage. In this work, polybenzimidazole with a high tensile strength of ∼100 MPa, an anion (or proton) conducting polymer electrolyte when doped with KOH (or H3PO4), was employed to fabricate highly robust and flexible supercapacitors. The polybenzimidazole film was integrated with activated carbon electrodes coated on graphite paper. These flexible supercapacitors exhibited low equivalent series resistance and good cycling stability of capacitance retention above 90% after 10000 cycles. Under mechanical deformations of bending, twisting, and rolling as well as a repeated bending test, the electrochemical performance of the flexible supercapacitors was well maintained, demonstrating good flexibility. The integration design showed better reliability against mechanical damage. It is an advantage for flexible supercapacitors with high energy density in mass production especially for devices based on KOH doped polybenzimidazole. This work suggests that polybenzimidazole based ion conducting polymer electrolytes are very promising for developing highly robust flexible supercapacitors in future practical applications.