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

Abstract 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‐MnO 2 and α‐Fe 2 O 3 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 MnO 2 //Fe 2 O 3 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 MnO 2 //Fe 2 O 3 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.