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. This journal is