Defective graphene as promising anode material for Na- and Ca-ion battery

Defective graphene as promising anode material for Na- and Ca-ion battery

ACS Applied Materials and Interfaces [ PDF ] 

Because of their abundance, sodium and calcium can be attractive in ion batteries for large-scale grid storage. However, many of the anode materials being pursued have limitations including volume expansions, lack of passivating films, and slow kinetics. Here, we investigate the adsorption of Na and Ca on graphene with divacancy and Stone-Wales defects in graphene. Our results show that although adsorption of Na and Ca is not possible on pristine graphene, enhanced adsorption is observed on defective graphene becuause of increased charge trnasfer between the adatoms and defects. We find that the capacity of graphene increases with the density of defects. For the maximum possible divacancy defect densities, capacities of 1450 and 2900 mAh/g for Na- and Ca- ion batteries, respectively, can be achieved. For Stone-Wales defects, we find maximum capacities of 1071 and 2142 mAh/g for Na and Ca,respectively. Our results provide guidelines to create better high-capacity anode materials for Na- and Ca-ion batteries.