Facile controlled synthesis of MnO₂ nanostructures for high-performance anodes in lithium-ion batteries

At present, new electrode materials still need to be developed to enhance the energy density, cyclability, initial coulombic efficiency and rate capability of lithium-ion batteries (LIBs). Here, we report a simple, rapid, cost-effective and novel technology to prepare MnO₂ through the decomposition of KMnO₄ under different pH values without surfactants or high temperatures. Moreover, the formation mechanisms of curly MnO₂ nanosheets, flower-like MnO₂ and onion-like MnO₂ are analyzed in depth. The great variation in the electrochemical performance of MnO₂ prepared under different pH values clearly indicates the importance of the nanostructure. Furthermore, curly MnO₂ nanoflakes fabricated at pH 2 (pH2-MnO₂) show good initial coulombic efficiency (ca. 80%) and long cyclability (ca. 1038 mAh g⁻¹ over 150 cycles), which is attributed to their relatively large surface area and stable structure.