Iri-BN Monolayer and Iri-BN/Iri-G Heterostructure as High-Performance Potassium-Ion Battery Anodes: Effects of Strain Engineering and Built-In Electric Field on the Adsorption and Diffusion of Potassium

Abstract

Based on first-principles calculations, we propose a novel two-dimensional porous boron nitride allotrope named Iri-BN and systematically investigate the effects of strain engineering and built-in electric field on the performance of potassium adsorption and diffusion. Iri-BN exhibits outstanding structural stability and excellent mechanical flexibility. (1) Compared with Iri-G, Iri-BN achieves an exceptionally low diffusion barrier of 0.085 eV (0.19 eV for Iri-G), a comparable average open-circuit voltage of 0.64 V (0.62 V for Iri-G), and a high theoretical specific capacity of 1439.92 mA h g–1 (Iri-G: 1175.78 mA h g–1). (2) Applying biaxial strain further enhances potassium adsorption strength (from −1.21 eV to −2.09 eV) while maintaining a relatively low diffusion barrier of 0.13 eV, thereby achieving synergistic optimization of adsorption capacity and kinetic performance. (3) A strong synergistic enhancement effect is observed in the Iri-BN/Iri-G heterostructure: For Iri-G, the enhancement of K adsorption is accompanied by a decreased diffusion barrier for K. For Iri-BN, K adsorption is likewise strengthened. Although the diffusion behavior of K is suppressed, the resulting diffusion kinetics remain within a reasonable regime. Collectively, these comprehensive characteristics fully demonstrate that Iri-BN and the Iri-BN/Iri-G heterostructure possess great potential as high-performance anode materials for potassium-ion batteries.