Rational design of black phosphorene/g-C₃B heterostructures as high-performance electrodes for Li and Na-ion batteries

Despite its superior electrochemical kinetics, black phosphene (BP) suffers from structural instability and chemical sensitivity as anodes materials for lithium and sodium-ion batteries (LIBs and SIBs). In this work, we design a novel BP/g-C₃B heterostructure and study its potential as an anode for both LIBs and SIBs using first-principles calculations with vibrational correction analysis. The BP/g-C₃B heterostructure shows enhanced electronic property and structural stability with ultrahigh interlayer stiffness of 275–344 N m⁻¹, almost one order of magnitude higher than that of black phosphene (21–98 N m⁻¹). Due to the interlayer synergetic effect, the Li/Na specific capacity of the BP/g-C₃B heterostructure can reach up to 479.5 and 527.5 mAh g⁻¹ with the formation of Li_2.5C₃BP₃ and Na_2.75C₃BP₃, much higher than the theoretical capacity limit of pristine graphene and phosphorene. Furthermore, the heterostructure shows low Li/Na diffusion barriers of 94 and 46 meV on the BP outer surface with superior ionic diffusivity. The vibrational analysis unveils smaller vibrational frequencies and weaker interaction between Na and the heterostructure, indicating superior Na kinetics in the BP/g-C₃B heterostructure compared to that of Li. The above merits render the BP/g-C₃B heterostructure as a promising anode candidate for both Li and Na-ion batteries.