Ultrafast high-energy micro-supercapacitors based on open-shell polymer-graphene composites

Abstract

Micro-supercapacitors are poised to serve as on-chip power sources for electronics. However, the challenge to simultaneously increase their power, energy, and lifetime demands new material combinations beyond current carbon-based systems. Here, we demonstrate that electro-deposition of an open-shell conjugated polymer with reduced graphene oxide achieves electrodes with capacitance up to 186 mF cm −2 (372 F cm −3 ). The extended delocalization within the open-shell polymer stabilizes redox states and facilitates a 3 V wide potential window, while the hierarchical electrode structure promotes ultrafast kinetics. The micro-supercapacitor shows a high power density of 227 mW cm −2 with an energy density of 10.5 μWh cm −2 and stability of 84% capacitance retention after 11,000 cycles. These attributes allow operation at 120 Hz for fast charging and alternating current (AC) line filtering applications, which may be suitable to replace bulky electrolytic capacitors or serve as high-endurance energy storage for wireless electronics. • A new class of open-shell conjugated polymer-based composite electrodes • Electrodes incorporating polymers with extended delocalization facilitating 3 V redox stability window • Ultrafast kinetics compatible with a typical AC line frequency of 60 Hz • Suitable replacement for bulky electrolytic capacitors, reducing volume by >10 times Micro-supercapacitors are promising for on-chip power sources. Yao et al. show that the electro-polymerization of an open-shell conjugated polymer with reduced graphene oxide enables hierarchical electrodes for micro-supercapacitors, simultaneously increasing their power, energy, and lifetime for wireless electronic applications.