One-pot achievement of La2O3/MnO2 nanocomposites as efficient electrodes for asymmetric supercapacitors

La2O3/MnO2 (La-Mn) nanocomposites were achieved via using KMnO4 and LaCl2 as starting materials in an aqueous solution followed by hydrothermal and high-temperature treatment processes. The microstructure and chemical composition of as-prepared La-Mn composites were characterized by a series of techniques such as XRD, SEM, TEM, HRTEM, XPS and BET. The results show that the pure La2O3 microspheres were covered with its large amount of well-ordered nanorods, and MnO2 was distributed evenly on La2O3 surface to constitute La-Mn composites. Meanwhile, the electrochemical tests reveal that sample Mn-La exhibited the highest specific capacitance (C-m) of 1231 Fg(-1) at a current density of 1 Ag-1, good rate performance and excellent cycling stability (98.5% capacitance retention after 5000 cycles at current density of 1 Ag-1). Such nanostructures endow the electrodes with short electrons, ion diffusion paths, and abundant charge adsorption sites. Excellent cycle performance is demonstrated by the built MnO2/La2O3//AC asymmetric cell, which has a high energy density of 44.1 WhKg(-1) and power density of 701 WKg(-1) at 1 Ag-1. Because of this, the resulting supercapacitors may prove useful in the development of devices with high energy and power densities.