Facile synthesis route to highly crystalline mesoporous γ-MnO2 nanospheres

Hierarchical mesoporous gamma-MnO2 nanospheres with high crystallinity were prepared by a template-free self-assembly under applied ultrasonic waves, resulting in a solid spherical nanostructure with stacking of nanosized worm-like particles. This approach based on ultrasound exposure reduces the particle size and enhances the crystallinity of gamma-MnO2, leading to a large effective area for the active domains and a stable structural arrangement of the active materials. The applicability of gamma-MnO2 to high-power lithium batteries is demonstrated, based on improved capacity, excellent rate capability, and stable cyclability, which stem from the outstanding physical properties of the hierarchical mesoporous nanostructure. (C) 2011 Elsevier B.V. All rights reserved.