Controlled Construction of Hierarchical Nanocomposites Consisting of MnO₂ and PEDOT for High‐Performance Supercapacitor Applications

Abstract

Abstract The integration of hierarchical nanostructure design and encapsulation strategies using a combination of electrochemical deposition, hydrothermal, and in situ reaction methods has been recognized as one of the most effective strategies to realize practical applications of various supercapacitor materials. Herein, a facile and scalable method is developed to synthesize a core–shell–branch hierarchical MnO 2 @PEDOT@MnO 2 composite by using a simple electrochemical deposition strategy. The proposed synthesis method facilitates the structural integration of three‐dimensional nickel foam and the synergy of different electroactive materials, which offers several advantages including simplicity, efficiency, no binder, and low cost. The as‐prepared, freestanding, hierarchical MnO 2 @PEDOT@MnO 2 electrodes exhibit high specific capacitance and rate capability. An asymmetric supercapacitor is fabricated with the hierarchical MnO 2 @PEDOT@MnO 2 nanocomposite as the positive electrode, activated carbon as the negative electrode, and Na 2 SO 4 aqueous solution as the electrolyte. The asymmetric supercapacitor can be cycled reversibly in a high‐voltage window of 0–1.8 V and exhibits a high energy density of 47.8 Wh kg −1 at a power density of 180 W kg −1 , indicating remarkable rate capability as well as reasonable cycling performance with 91.3 % retention after 5000 cycles.