Fast assembling MnO2-network electrode materials to achieve high performance asymmetric aqueous supercapacitors

Abstract

Manganese dioxide (MnO2) is a promising supercapacitive material due to the advantages of low cost, natural abundance and friendly environment. Nevertheless, it generally presents an unsatisfactory supercapacitive performance due to the poor utilization rate in the charge/discharge process and the sluggish charge (electrons/ions) transfer kinetics. Constructing a 3D MnO2 network is a promising way to solve the above problems, but usually suffers from a prolonged reaction time or a high-heating source that makes them unfavorable for practical applications. Here, we developed a one-pot, fast and cost-effective method to assemble 3D MnO2 network electrode materials within 10 min. The MnO2-network materials present a high utilization rate and a fast charge transfer capability. As an aqueous supercapacitor electrode, it exhibited a high specific capacitance of 382 F g−1 at 1 A g−1 and ranked among the intrinsic MnO2 materials at the top level. The corresponding asymmetric supercapacitor coupled with activated carbon delivered a high energy density of 44 Wh kg−1 at a power density of 277 W kg−1 and maintains 91.2 % capacitance retention after 10,000 cycles at 10 A g−1. This work paves the way for simple, environmental-friendly, and rapid methods to gain the high-performance MnO2 electrode materials for supercapacitors.