Understanding Na-ion adsorption in nitrogen doped graphene oxide anode for rechargeable sodium ion batteries

Na-ion batteries (NIBs) are promising alternative to Li-ion batteries due to the abundance resources of Na and low fabrication cost. After the successful synthesis of graphene, its derivative drew huge attention as a new class of potential anode materials for NIBs. Here, nitrogen-doped graphene oxide (NDGO) has been explored as promising anode materials for high-performance NIBs. First-principles calculations have been carried out to understand the adsorption behavior, cycling stability and electrochemical properties of NDGO. The influence of epoxide groups in NDGO towards Na-ions adsorption and favorable adsorption sites on the nanosheets has also been investigated. The Na-ions near the epoxide groups were adsorbed with an adsorption energy of about -2.38 eV while far from epoxide groups, the adsorption energy is about -0.45 eV. The DOS spectra reveal that nanosheets have metallic behavior during sodiation. The specific capacities were found to be as high as 714, 1034 and 1149.32 mAh/g for mono, di and tri-epoxide groups containing NDGO respectively, which are 2.5-3.5 times higher than the hard carbon for NIBs. Moreover, the average open-circuit voltages were 0.54 V, 0.80 V and 1.04 V for mono, di and tri- epoxide groups containing NDGO respectively, which are high enough to help with suppressing the dendrite formation.

Automated summary

This study investigates the potential of nitrogen-doped graphene oxide as high-performance anode materials for Na-ion batteries and explores their adsorption behavior and electrochemical properties through first-principles calculations. The results show that the position of epoxide groups in NDGO affects the adsorption energy of Na ions, significantly impacting the energy density.