Phosphorene as cathode for metal-ion batteries: Importance of F decoration

Metal-ion batteries are widely used energy storage devices. Commercial cathode materials show high voltages but low capacities, limiting energy densities. Although phosphorene has been prepared and delivers a high capacity, the low voltage is problematic for cathode. The structural, electronic, and electrochemical properties of F-decorated phosphorene for metal-ion batteries are investigated using first-principles calculations. The F atoms are converted during lithiation/sodiation/potassiation. Importantly, F-decorated phosphorene delivers a capacity of 536 mAh/g and voltages of 3.46, 3.09, and 2.95 V for lithiation, sodiation, and potassiation, respectively, which leads to high energy densities of 1856, 1657, and 1582 mWh/g. Graphene coating improves stability of F-decorated phosphorene.