Manganese dioxide-anchored three-dimensional nitrogen-doped graphene hybrid aerogels as excellent anode materials for lithium ion batteries

The capacity of manganese dioxide (MnO₂) deteriorates with cycling due to the irreversible changes induced by the repeated lithiation and delithiation processes. To overcome this drawback, MnO₂/nitrogen-doped graphene hybrid aerogels (MNGAs) were prepared via a facile redox process between KMnO₄ and carbon within nitrogen-doped graphene hydrogels. The three-dimensional nitrogen-doped graphene hydrogels were prepared and utilized as matrices for MnO₂ deposition. The MNGAs-120 obtained after a deposition time of 120 min delivered a very high discharge capacity of 909 mA h g^-1 after 200 cycles at a current density of 400 mA g^-1, in sharp contrast to only 280 and 70 mA h g^-1 delivered from nitrogen-doped graphene aerogels and MnO₂. This discharge capacity is superior to that of the previously reported MnO₂/carbon based hybrid materials. This material also exhibited an excellent rate capability and cycling performance. Its superior electrochemical performance can be ascribed to the synergistic interaction between uniformly dispersed MnO₂ particles with high capacity and the conductive three-dimensional nitrogen-doped graphene network with a large surface area and an interconnected porous structure.