Two-dimensional C3N/blue phosphorene vdW heterostructure for Li, Na and K-ion batteries

Abstract

Blue phosphorene (BP), an allotrope of black phosphorus, is likely to oxidize under ambient conditions, which significantly limits its use as an anode for ion (Li/Na/K) batteries. Here, we investigate a van der Waals heterostructure constructed using BP and C₃N. Using density functional theory, we show that C₃N/BP is a material with a tiny band gap and shows potential for intercalating ions due to the large interlayer spacing. We then examine the structural stability and electronic structure for its potential use as an anode for lithium-, sodium- and potassium-ion batteries. The energetics of the systems establish that the Li, Na and K ions prefer the C₃N/BP heterostructure instead of their isolated components. We further used the nudged elastic band technique to find out that the energy barrier (0.046 eV) for sodium ions is the lowest among the three for the various diffusion pathways that we investigated. Furthermore, the heterostructure also possesses a large storage capacity (1511.44 mA h g⁻¹) for sodium. In fact, when compared to other heterostructures, C₃N/BP stands out for its storage capacities for all of the ions under investigation. Owing to properties such as its minimum energy barrier and high storage capacity as compared to other BP-based heterostructures, we believe that the C₃N/BP HS could be used as a potential anode material for Li, Na and K-ion batteries.