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

Demonstration of SiB₁₁BO₁₂ ⁻ anion's colossal stability and application as high-voltage electrolytes in alkali metal-ion batteries. Being non-hazardous, halogen-free, highly stable, and super-halogen, SiB₁₁BO₁₂ ⁻-based electrolytes possess a large operating potential and rapid ion conductivity.

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.

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