Identification of Non-Carbonaceous Cathodes in Al Batteries: Potential Applicability of Black and Blue Phosphorene Monolayers.

In the present era of growing energy demands, low-dimensional materials are emerging as the suitable choices for energy storage due to their excellent ion transport properties, improved reversible capacity, fine rate performance and good cycling stability. In this context, we have investigated the applicability of black and blue phosphorene monolayers as potential cathodes for Al batteries. Both black and blue phosphorene monolayers show similar electrochemical behavior as that of experimentally reported graphite with a charge transfer from the surface in order to bind the tetrahedral geometry of AlCl4 during the charging process. The adsorption of AlCl4 drives semiconductor-to-metallic transformation of black/blue phosphorene, which ensures constant conductivity in Al batteries. Following the systematic adsorption of AlCl4 , the voltage for black and blue phosphorene is calculated to be ≈1.50 V and ≈1.80 V with storage capacities of 144 mAh g-1 and 108 mAh g-1 , respectively. Besides, low diffusion barriers of 0.11 eV and 0.14 eV are predicted for AlCl4 on the respective systems of black and blue phosphorene monolayers. Our work suggests that both black and blue phosphorene monolayers can be potential cathodes for Al batteries with delivery of high storage capacity and high voltage, respectively.