Low-Cost MnO2 Nanoflowers and La2O3 Nanospheres as Efficient Electrodes for Asymmetric Supercapacitors

While supercapacitors can deliver high electrical power, their low energy density limits their application. Here, we designed and fabricated a facile asymmetric supercapacitor (ASC) with excellent electrochemical performance, where MnO(2 )nanoflowers (NFs) and La2O3 nanospheres (NSs) were successfully electrodeposited onto carbon paper as work electrodes in an aqueous 0.5 M Na2SO4 electrolyte. Such nanostructures endow the electrodes with short electrons, ion diffusion paths, and abundant charge adsorption sites. The assembled MnO2 NF//La2O3 NS asymmetric cell presents a gravimetric energy density of 80.56 Wh kg(-1), a volumetric energy density of 0.74 mWh cm(-3) at 35.71 mA cm(-3), and excellent cycle performance. Moreover, a packaged device displays a superior energy density of 0.49 mWh cm(-3) with a power density of 94.29 mW cm(-3). The satisfactory improvement in performance mainly stems from the homogeneous nanostructured architecture and an extended workable potential region of 0-2.0 V. The resulting supercapacitors could have great potential for designing high energy and power density devices as effective power sources.