Unveiling the potential of 3D TH-graphyne: a porous carbon anode for efficient potassium-ion storage

Abstract Due to the abundance and low cost of potassium resources, potassium-ion batteries have emerged as promising alternatives to Li-ion batteries, with high capacity and fast ion transport. This study presents a novel three-dimensional triangular-hexagonal graphyne-like (3D TH-GY) carbon allotrope engineered by incorporating acetylenic linkers. Ab initio calculations confirm that the semi-metallic 3D TH-GY is thermally and dynamically stable, having a small bandgap of 0.04 eV. The electrochemical potential of 3D TH-GY, along with a recently proposed two-dimensional porous carbon allotrope (TH-GY), is assessed as an anode material for KIBs via DFT calculations. The study reveals strong K-ion binding, with values of –0.97 eV for 2D TH-GY and –1.53 eV for 3D TH-GY, respectively, facilitating efficient ion intercalation while ensuring favorable desorption kinetics. The calculated diffusion barriers for K-ion migration are exceptionally low (0.036 eV for 2D TH-GY, 0.12 eV for 3D TH-GY), indicating rapid ion transport across the surface. Moreover, the theoretical capacities of 2D TH-GY and 3D TH-GY reach 929.83 and 495.91 mAh g −1 , respectively, positioning them as promising candidates for high-performance charge–discharge cycles in KIBs. The combination of high charge storage capacity, fast ion diffusion, and structural robustness highlights TH-GY-based materials as compelling alternatives for next-generation potassium-ion battery anodes.