Two-dimensional C5678: a promising carbon-based high-performance lithium-ion battery anode

Abstract

The non-hexagonal carbon rings significantly affect the electrode application of two-dimensional carbon allotropes. Many studies have been devoted to exploring novel two-dimensional carbon allotropes. However, two-dimensional carbon allotropes with a high degree of the local carbon-ring disorder are still nonexistent. Here, we design a new metallic two-dimensional planar carbon allotrope C₅₆₇₈ by using first-principles calculations. C₅₆₇₈ is composed of pentagonal, hexagonal, heptagonal, and octagonal carbon rings with a higher degree of local carbon-ring disorder. It has good dynamic, thermal, and mechanical stability. The local carbon-ring disorder results in many local electron-deficient regions and local strain regions on the basal plane of C₅₆₇₈ that can accommodate more electrons from lithium atoms and increase the adsorption sites, respectively, thus further enhancing the lithium storage capacity. It has a one-sided maximum theoretical capacity of 697 mA h g⁻¹, a lower Li diffusion barrier (<0.44 eV), and a lower average open-circuit voltage (0.33 V). These results not only propose a candidate electrode material for a lithium-ion battery but also offer insights for understanding the effect of non-hexagonal carbon rings on lithium adsorption and storage.