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 SiB 11 (BO) 12 − . Because of the weak π‐orbital interaction of −BO as well as the mixed covalent and ionic interaction between SiB 11 ‐cage and −BO ligand, SiB 11 (BO) 12 − has colossal stability. SiB 11 (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, SiB 11 (BO) 12 − is thermodynamically stable at high temperatures, and its large size allows for faster cation movement. The alkali salts MSiB 11 (BO) 12 (M=Li, Na, and K) are easily dissociated into ionic components. Electrolytes based on SiB 11 (BO) 12 − greatly outperform commercial electrolytes. In short, SiB 11 (BO) 12 − ‐based compound is demonstrated to be a high‐voltage electrolyte for AMIBs.