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 La 2 O 3 nanospheres (NSs) were successfully electrodeposited onto carbon paper as work electrodes in an aqueous 0.5 M Na 2 SO 4 electrolyte. Such nanostructures endow the electrodes with short electrons, ion diffusion paths, and abundant charge adsorption sites. The assembled MnO 2 NF//La 2 O 3 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.
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