Bendable All-Solid-State Asymmetric Supercapacitors based on MnO2 and Fe2O3 Thin Films

The growing interest in portable and consumable electronics demands efficient and low-cost energy storage devices with excellent flexibility and of light weight. We demonstrate flexible high-performance all-solid-state thin-film asymmetric supercapacitors (ASSTF-ASCs) using α-MnO2 and α-Fe2O3 thin films as positive and negative electrodes, respectively. The as-fabricated ASSTF-ASC devices have excellent electrochemical performance with extended potential window of 2.0 V and excellent cycling stability for 2500 cycles. Impressively, an MnO2//Fe2O3 asymmetric cell demonstrates high specific capacitance of 145 F g−1 with a high energy density of 41 Wh kg−1 while maintaining a power density of 2.1 kW kg−1. A parallel combination of two MnO2//Fe2O3 asymmetric cells is able to illuminate a panel of 31 light emitting diodes (LEDs). These findings may offer new opportunities for the use of asymmetric configurations in energy storage devices for various portable electronic systems.