First-Principles Investigation of 2D Copper Boride as a High-Performance Anode for Lithium-Ion Batteries

In this study, we investigate the two-dimensional copper boride, Cu$_8$B$_{14}$, as a possible anode material for lithium-ion batteries using first-principles calculations. We found that the structural integrity of the monolayer was preserved even at elevated temperatures, while electronic calculations confirm the metallic character of the pristine and Li-loaded systems. On systematic lithiation on Cu$_8$B$_{14}$ a specific capacity of 430mAhg$^{-1}$ was obtained. A Li diffusion barrier of 0.32eV for the most favourable path, along with a diffusivity of approximately $2.26 \times 10^{-5}$cm$^2$s$^{-1}$ was obtained. The open-circuit voltage of 0.53 V falls within the optimal anode range of 0.1--1.0 V. These combined characteristics point to Cu$_8$B$_{14}$ as a compelling candidate for advanced battery anodes. Furthermore, to understand the defect and its effect on different parameters, we investigated an experimentally identified line-defect configuration of copper boride. The line defect monolayer retains a theoretical capacity of about 385mAhg$^{-1}$, while the introduced line defect further reduces the Li migration barrier to 0.21eV, yielding an enhanced macroscopic diffusivity of $\sim$5.6$\times$10$^{-4}$cm$^{2}$s$^{-1}$ and confirming that structural defects accelerate Li-ion transport kinetics in this material.