Dispersed MnO 2 nanoparticles/sugarcane bagasse-derived carbon composite as an anode material for lithium-ion batteries.

Bagasse-derived carbon electrodes were developed by doping with nitrogen functional groups and compositing with high-capacity MnO 2 nanoparticles (MnO 2 /NBGC). The bagasse-derived biochar was N-doped by refluxing in urea, followed by the deposition of MnO 2 nanoparticles onto its porous surface via the hydrothermal reduction of KMnO 4 . Different initial KMnO 4 loading concentrations ( i.e. 5, 10, 40, and 100 mM) were applied to optimize the composite morphology and the corresponding electrochemical performance. Material characterization confirmed that the carbon composite has a mesoporous structure along with the dispersion of MnO 2 nano-particles on the N-containing carbon surface. It was found that the 5-MnO 2 /NBGC sample exhibited the highest electrochemical performance with a reversible capacity of 760 mA h g -1 at a current density of 186 mA g -1 . It delivered reversible capacities of 488 and 390 mA h g -1 in cycle tests at 372 and 744 mA g -1 , respectively, for 150 cycles and presented good reversibility with nearly 100% coulombic efficiency. In addition, it could exert high capacities up to 388 and 301 mA h g -1 even under high current densities of 1860 and 3720 mA g -1 , respectively. Moreover, most of the prepared composite products showed high rate capability with great reversibility up to more than 90% after testing at a high current density of 3720 mA g -1 . The great electrochemical performance of the MnO 2 /NBGC nanocomposite electrode can be attributed to the synergistic impact of the hierarchical architecture of the MnO 2 nanocrystals deposited on porous carbon and the capacitive effect of the N-containing defects within the carbon material. The nanostructure of the MnO 2 particles deposited on porous carbon limits its large volume change during cycling and promotes good adhesion of MnO 2 nanoparticles with the substrate. Meanwhile, the capacitive effect of the exposed N-functional groups enables fast ionic conduction and reduces interfacial resistance at the electrode interface.