LAUSR

Abstract In this paper, porous waxberry-like microspheres structures of MnO 2 /La 2 O 3 (Mn-La) composites were synthesized via a facile two-pot hydrothermal method. The microstructure and chemical composition of as-prepared Mn-La composites were characterized by a series of techniques such as XRD, SEM, TEM, HRTEM, XPS and BET. The results show that the pure MnO 2 microspheres were covered with its large amount of well-ordered nanorods, and La 2 O 3 was distributed evenly on MnO 2 surface to constitute Mn-La composites. Meanwhile, the electrochemical tests reveal that sample Mn-La10 (molar ratio n MnO 2 : n La 2 O 3  = 1:0.1) exhibited the highest specific capacitance ( C m ) (245.4 F g −1 at a current density of 0.3 A g −1 , 1.5 times of MnO 2 ), good rate performance and excellent cycling stability (97.5% capacitance retention after 3000 cycles at current density of 2.0 A g −1 ). In general, suitable amount of La 2 O 3 doping, based on the synergistic effect between MnO 2 and La 2 O 3 , is helpful to improve the capacitance performance of composites. Furthermore, an asymmetric supercapacitor (Mn-La10//AC), with Mn-La10 as the positive electrode and activated carbons as the negative electrode, displays high energy density of 25.8 Wh kg −1 with a maximum power density of 0.3 kW kg −1 under potential window of 2.0 V.