Superhigh capacity and rate capability of high-level nitrogen-doped graphene sheets as anode materials for lithium-ion batteries

A new facile approach is proposed to synthesize nitrogen-doped graphene sheets with the nitrogen-doping level as high as 7.04 at.% by thermal annealing pristine graphene sheets and low-cost industrial material melamine. The high-level nitrogen-doped graphene sheets exhibit a superhigh initial reversible capacity of 1123 mAh g−1 at a current density of 50 mA g−1. More significantly, even at an extremely high current density of 20 A g−1, highly stable capacity of about 241 mAh g−1 could still be obtained. Such an electrochemical performance is superior to those previously reported nitrogen-doped graphene sheets. The excellent electrochemical performance can be attributed to the two-dimensional structure, disordered surface morphology, high nitrogen-doping level, and the existence of pyridinic nitrogen atoms. The results indicate that the high-level nitrogen-doped graphene sheets could be a promising anode material for high-performance lithium-ion batteries.

► N-doped graphene was synthesized by annealing the pristine graphene and melamine.
► The atomic percentage of nitrogen in the sample is as high as 7.04 at.%.
► The material shows a good cycle performance and excellent rate capability.