Facile Synthesis of Nanostructured MnO₂ as Anode Materials for Sodium‐Ion Batteries

Abstract Nanostructured MnO₂ (including nanorods and nanoflowers) has been synthesized by a simple two‐step hydrothermal method and thermal treatment. When employed as anode materials for sodium‐ion batteries, MnO₂ nanorods and nanoflowers demonstrate high initial sodium ion storage capacities of 427.4 and 487.8 mA h g⁻¹, respectively, at a current density of 50 mA g⁻¹. Compared with MnO₂ nanorods, MnO₂ nanoflowers achieved a much better electrochemical performance including good rate capability (103.3 mA h g⁻¹ at 800 mA g⁻¹ after 100 cycles) and superior cyclability (133.6 mA h g⁻¹ at 400 mA g⁻¹ after 1000 cycles). The good performance can be ascribed to the nanocrystalline nature and the three‐dimensional hierarchical architecture of MnO₂ nanoflowers, which promotes the contact between MnO₂ and electrolyte and shortens the electronic sodium ion pathway in the charge and discharge processes.