Nitrogen-doping of chemically reduced mesocarbon microbead oxide for the improved performance of lithium ion batteries

Nitrogen was doped into chemically-reduced mesocarbon microbead oxide (CR-MCMBO) through simple annealing in ammonia at 800 °C, and the Li-ion storage properties of the prepared nitrogen-doped CR-MCMBO (NR-MCMBO) was studied. It was found that NR-MCMBO shows a highly reversible capacity of 762 mAh g−1 at 20 mA g−1 during the first charge process, which is much higher than that of the pristine MCMB (289 mAh g−1), and the specific capacity of NR-MCMBO still had a value of 535 mAh g−1 after 200 cycles. When the current density reaches 1000 mA g−1, the specific capacity of NR-MCMBO is 388 mAh g−1. The high reversible capacity of NR-MCMBO is attributed to the high amount of pyridinic nitrogen and the large number of defects induced by oxidation and nitrogen-doping. Moreover, the open pores constituted by graphene-like nanoplatelets on the spherical NR-MCMBO surface facilitate the diffusion of Li ions.