Phosphine-Based Porous Organic Polymer/rGO Composite Anode and α-MnO_2 Nanowire Cathode Cooperatively Enabling High-Voltage Aqueous Asymmetric Supercapacitors

摘要

Aqueous supercapacitors often yield a restricted cell voltage, resulting in a low specific energy, due to unwanted water electrolysis and a narrow electrode potential range. Herein, a novel hierarchical nanostructured phosphine based porous organic polymer (PP)/reduced graphene oxide (rGO) aerogel composite anode is fabricated. Benefitting from the excellent electrical conductivity and ultra-thin protection layer of rGO aerogel, PP/rGO could extend the potential window to -1.0-0 V, exhibiting significantly enhanced specific capacitance (380.2 F/g@2 A/g) and good rate capability (165.0 F/g@4 A/g). To complement the wide potential window, alpha-MnO2 nanowire is employed as cathode due to its large and stable potential window (0 to 0.8 V). Remarkably, a 2 V aqueous PP/rGO//alpha-MnO2 asymmetric supercapacitor (ASC) is successfully fabricated, exhibiting a high specific energy of 39 Wh/kg with extraordinary cycling stability and rate capability (96% retention after 10000 cycles), outperforming most of the previously reported rGO based ASCs. Furthermore, a coin-type PP/rGO//alpha-MnO2 ASC device is further fabricated that can illuminate a red LED for 3 mins, demonstrating its great potential for practical application. The knowledge gained in this study using in situ formed hetero-nanostructure to expand the voltage window will open up new possibilities for electrode design targeting a widen potential window and high energy ASCs.