Hierarchically Structured MnO/Nitrogen-Doped Carbon Nanocomposites as High-Rate and Long-Life Anodes for Lithium-Ion Batteries

Among various anode materials, manganese oxide (MnO) is evaluated as a promising alternative to graphite due to its low lithium insertion voltage, environmental friendliness, low cost, and high theoretical specific capacity. However, its poor inherent conductivity and inadequate cycling stability limit its practical applications. This study proposes a coordination polymer-derived method for the controllable preparation of two hierarchically structured manganese oxide/nitrogen-doped carbon (MnO/NC) nanocomposites with flower-like structure and hollow microsphere structure. As anodes for lithium-ion batteries, both nanocomposites demonstrate a remarkable lithium storage performance. Especially, the hollow microsphere-structured MnO/NC nanocomposites exhibited enhanced rate capability and prolonged cycle life, delivering 1035 and 702 mAh g–1 after 1000 cycles at 1 and 2 A g–1. Additionally, at a low temperature of 0 °C and a current density of 1 A g–1, the nanocomposite maintains a capacity of 549 mAh g–1 after 300 cycles. The synergistic effect of the hollow-structured microspheres and the uniform nitrogen-doped carbon coating endow the material with excellent electrochemical performance. This structure not only inhibits the aggregation of MnO/NC nanoparticles and maintains structural stability but also shortens the diffusion paths for lithium ions and electrons, thereby enhancing the ion diffusion rates. Furthermore, it improves electrical conductivity and increases the electrode–electrolyte contact area while alleviating volume expansion during cycling. As a result, the material exhibits a significantly enhanced rate capability and cycling stability.