Porous waxberry-like MnO₂/La₂O₃microspheres for high performance asymmetric supercapacitor.

Yu Li, Bing Guan, Aimee Maclennan, Yongfeng Hu, Dandan Li, Jing Zhao, Yaqiong Wang, Huaihao Zhang*.

^aCollege of Chemistry and Chemical Engineering, Yangzhou University

^bCanadian Light Source, 44 Innovation Boulevard, Saskatoon, SK, Canada S7N 2V3

Abstract:In this paper, porous waxberry-like microspheres structures of MnO₂/La₂O₃(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 MnO₂microspheres were covered with its large amount of well-ordered nanorods, and La₂O₃was distributed evenly on MnO₂surface to constitute Mn-La composites. Meanwhile, the electrochemical tests reveal that sample Mn-La10 (molar ratio nMnO₂:nLa₂O₃=1:0.1) exhibited the highest specific capacitance (Cm) (245.4 F g-1 at a current density of 0.3 A g-1, 1.5 times of MnO₂), 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 La₂O₃doping, based on the synergistic effect between MnO₂and La₂O₃, 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 potentialwindow of 2.0 V.

Electrochimica Acta, 2017, DOI: 10.1016/j.electacta.2017.04.175. IF=4.803

文章链接: http://dx.doi.org/10.1016/j.electacta.2017.04.175