Optimization of the Properties of Functionalized BC3 Monolayer for Superior Electrode of Solid-State Sodium-Ion Batteries

Abstract

Solid-state batteries offer superior safety, high energy density, and the ability to function effectively across a wide range of temperatures. Sodium-ion (Na-ion) solid-state batteries are a promising alternative to lithium-ion batteries due to sodium's abundance and low cost. A high-quality electrode is crucial for achieving high performance in Na-ion batteries. In this study, structural stability, electronic properties, and performance of functionalized hexagonal boron carbide (BC<inf>3</inf>) are investigated for ultrathin electrodes using density functional theory (DFT). The effective adsorption of Li, Na, K, and Mg atoms at the BC<inf>3</inf> surface is also investigated. The BC<inf>3</inf> monolayer has a ?0.8 eV indirect bandgap, which becomes metallic after Na adsorption, making it suitable for electrode applications. Additionally, the Na-adsorbed BC<inf>3</inf> monolayer shows the lowest adsorption energy (?1.2 eV), which is the most stable lattice structure among others. The Na-adsorbed BC<inf>3</inf> demonstrated a theoretical capacity of 1152 mAh g?1, which is comparable with the Li-adsorbed electrode. Moreover, the Na-adsorbed BC<inf>3</inf> electrode shows a very small variation (0.18 V) for open circuit voltage (OCV), indicating this electrode is robust in terms of voltage stability. These findings show that the functionalized BC<inf>3</inf> ultrathin electrode is very suitable for the electrode of Na-ion solid-state batteries. © 2025 Wiley-VCH GmbH.