Tuning the Mechanical and Na-Ion Diffusion Properties of Boron Nitride via Twist Angle Engineering for Sodium-Ion Batteries

While sodium-ion batteries (SIBs) offer a low-cost and sustainable alternative to lithium-ion systems, the development of suitable anode materials remains a key challenge. Boron nitride (BN), known for its high chemical and thermal stability, has attracted interest, but its poor conductivity and limited understanding of its stacking-dependent properties hinder its practical application. This study aims to investigate how different stacking configurations and twist angles in BN structures influence their mechanical properties, Na+ diffusion behavior, and electronic characteristics to assess their suitability as anode materials for SIBs. Using density functional theory, we systematically analyze different BN stacking structures, including hexagonal (AA’-BN), Bernal (AB-BN), and twisted BN at various angles to evaluate their mechanical stability, Na+ intercalation behavior, phonon dynamics, and diffusion energy barriers. The results show that while most twisted BN configurations reduce mechanical strength, the AB-BN-21.8° structure retains mechanical properties comparable to those of AA’-BN and AB-BN. Phonon spectra confirm the dynamic stability of AA’-BN, AB-BN, and AB-BN-21.8°. After Na insertion, AB-BN-21.8° exhibits a smaller interlayer expansion (10.96%) and a significantly reduced Na+ interlayer diffusion barrier, indicating enhanced ion transport. Moreover, Na insertion markedly improves the electronic conductivity of BN, which is beneficial for enhancing the charge transport and overall electrochemical performance in sodium-ion batteries. Therefore, twist angle engineering can effectively enhance the electrochemical properties of BN, making AB-BN-21.8° a promising candidate for high-performance SIB anode materials. This work provides theoretical guidance for the design of next-generation two-dimensional energy storage materials.