A new 3D metallic carbon allotrope composed of penta-graphene nanoribbons as a high-performance anode material for sodium-ion batteries

Abstract

Three-dimensional (3D) porous metallic carbon allotropes composed of graphene nanoribbons have attracted increasing attention in recent years because of their novel properties, especially due to their potential as anode materials for metal-ion batteries. Here, for the first time, we propose a new 3D porous metallic carbon allotrope consisting of penta-graphene nanoribbons. This material has an orthogonal lattice with its unit cell containing 36 carbon atoms, thus it is named penta-oC36. Based on state-of-the-art first-principles calculations, we show that penta-oC36 is thermally and dynamically stable with a metallic electronic structure. Through a detailed analysis of the intercalation and diffusion processes of Na ions in this structure, we find that penta-oC36 possesses a large reversible capacity of 496.9 mA h g⁻¹, low diffusion energy barrier as low as 0.01 eV, and a low open-circuit voltage of 0.39 V, superior to many other anode materials for sodium-ion batteries (SIBs) reported so far. More importantly, this study expands the penta-carbon family from 2D semiconducting penta-graphene to 3D metallic penta-nanoribbon-based materials with intriguing properties.