Coupling of MnO with Heteroatom-Doped Reduced Graphene Oxide Aerogels with Improved Electrochemical Performances for Sodium-Ion Batteries.

Currently, efforts to address the energy needs of large-scale power applications have expedited the development of sodium-ion (Na-ion) batteries. Transition-metal oxides, including MnO, are promising for low-cost, eco-friendly energy storage/conversion. Due to its high theoretical capacity, MnO is worth exploring as an anode material for Na-ion batteries; however, its actual application is constrained by low electrical conductivity and capacity fading. Herein, we attempt to overcome the problems related to MnO with heteroatom-doped reduced graphene oxide (rGO) aerogels synthesised via the hydrothermal method with a subsequent freeze-drying process. The cubic MnO particles with an average size of 0.5-1.5 µm are distributed to both sides of heteroatom-doped rGO aerogels layers. Results indicate that heteroatom-doped rGO aerogels may serve as an efficient ion transport channel for electrolyte ion transport in MnO. After 100 cycles, the electrodes retained their capacities of 242, 325, and 277 mAh g, for MnO/rGO, MnO/nitrogen-rGO, and MnO/nitrogen, sulphur-rGO aerogels, respectively. Doping MnO with heteroatom-doped rGO aerogels increased its electrical conductivity and buffered volume change during charge/discharge, resulting in high capacity and stable cycling performance. The synergistic effects of heteroatom doping and the three-dimensional porous structure network of rGO aerogels are responsible for their excellent electrochemical performances.