NiO-graphene hybrid as an anode material for lithium ion batteries

A NiO-graphene hybrid is synthesized by a liquid phase deposition method. As an anode material for lithium ion batteries, the cyclic stability and rate capability of NiO is significantly improved after the incorporation of graphene sheets. The NiO-graphene hybrid electrode delivers a capacity of 646.1 mA h g(-1) after 35 cycles at a current density of 100 mA g(-1), corresponding to 86.3% capacity retention. When the current density is increased to 400 and 800 mA g(-1), it still maintains a capacity of 509 and 368.5 mA h g(-1), respectively. The thermodynamic and kinetic properties of NiO electrodes with and without graphene are investigated by galvanostatic intermittent titration technique. The relationship between the rate and voltage hysteresis is also discussed. The polarization of both the electrodes in all cases obeys ohmic rule in the present rate range. The incorporation of graphene sheets can partly reduce the voltage polarization thereby the voltage hysteresis with increasing the current density. However, the extrapolation to zero current ends up in an approximate residual voltage for both the NiO electrodes. (C) 2011 Elsevier B.V. All rights reserved.