Colossal Stability of SiB₁₁(BO)₁₂⁻: An Implication as Potential Electrolyte in High‐Voltage Alkali‐ion Battery

Abstract

High‐voltage alkali metal‐ion batteries (AMIBs) require a non‐hazardous, low‐cost, and highly stable electrolyte with a large operating potential and rapid ion conductivity. Here, we have reported a halogen‐free high‐voltage electrolyte based on SiB11(BO)12−. Because of the weak π‐orbital interaction of −BO as well as the mixed covalent and ionic interaction between SiB11‐cage and −BO ligand, SiB11(BO)12− has colossal stability. SiB11(BO)12− possesses extremely high vertical detachment energy (9.95 eV), anodic voltage limit (∼10.05 V), and electrochemical stability window (∼9.95 V). Furthermore, SiB11(BO)12− is thermodynamically stable at high temperatures, and its large size allows for faster cation movement. The alkali salts MSiB11(BO)12 (M=Li, Na, and K) are easily dissociated into ionic components. Electrolytes based on SiB11(BO)12− greatly outperform commercial electrolytes. In short, SiB11(BO)12−‐based compound is demonstrated to be a high‐voltage electrolyte for AMIBs.