Tetracyanobenzene-Al-graphene efficiency as an organic electrode material for Na-ion batteries: A theoretical approach

The current study aimed to investigate the tetracyanobenzene (TCNB) anchored on graphene as a possible organic electrode material for Na-ion batteries using density functional theory method. According to the obtained results, TCNB containing four cyanide functional groups could store four Na atoms with theoretical specific capacity of 601.80 mAh/g, a high considerable value. To reach high electrical conductivity and more stability, TCNB was connected to Al-graphene substrate. The average charge donation value of Na atoms seems considerable even in high concentration, 0.75|e| for sixth adsorbed Na atom. Notably, the bond strength between TCNB and Al-graphene was amplified by insertion of more Na atoms which increase the stability of TCNB-Al-graphene system. Partial density of states (PDOS) analysis indicated that TCNB significantly affected on sodium ionization and related binding energies. Na diffusion along considered paths revealed relatively facile sodium diffusion on graphene surface. The suitable voltage range obtained (0.5-2.5 V) indicates that applying this system as anode electrode material in Na-ion batteries might be highly promising. (C) 2017 Elsevier B.V. All rights reserved.