Facile synthesis route to highly crystalline mesoporous γ-MnO ₂ nanospheres

Hierarchical mesoporous γ-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 γ-MnO ₂, leading to a large effective area for the active domains and a stable structural arrangement of the active materials. The applicability of γ-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.