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Controllable Synthesis of Hollow Bipyramid β-MnO 2 and Its High Electrochemical Performance for Lithium Storage

2012; American Chemical Society; Volume: 4; Issue: 6 Linguagem: Inglês

10.1021/am300410z

1944-8252

Weimin Chen, Long Qie, Qingguo Shao, Lixia Yuan, Wuxing Zhang, Yunhui Huang,

Advanced Battery Materials and Technologies

Three types of MnO2 nanostructures, viz., α-MnO2 nanotubes, hollow β-MnO2 bipyramids, and solid β-MnO2 bipyramids, have been synthesized via a simple template-free hydrothermal method. Cyclic voltammetry and galvanostatic charge/discharge measurements demonstrate that the hollow β-MnO2 bipyramids exhibit the highest specific capacity and the best cyclability; the capacity retains 213 mAh g(-1) at a current density of 100 mA g(-1) after 150 cycles. XRD patterns of the lithiated β-MnO2 electrodes clearly show the expansion of lattice volume caused by lithiation, but the structure keeps stable during lithium insertion/extraction process. We suggest that the excellent performance for β-MnO2 can be attributed to its unique electrochemical reaction, compact tunnel-structure and hollow architecture. The hollow architecture can accommodate the volume change during charge/discharge process and improve effective diffusion paths for both lithium ions and electrons.