Ultra-low concentration ether electrolytes with strong Coulomb interactions for high-voltage lithium metal batteries

Abstract

The advancement of high-energy-density lithium metal batteries (LMBs) necessitates the development of novel electrolytes capable of withstanding high voltages. Ether-based electrolytes, while compatible with lithium metal anodes (LMAs), face limitations in high-voltage stability. Traditional design strategies with high concentration enhance the high-voltage stability of electrolytes by consuming free solvents to prevent their decomposition but face high-cost issues. Herein, we introduce a novel design approach for high-voltage ether electrolytes that leverages strong Coulomb interactions between lithium ions (Li⁺) and anions to construct an anion-dominated solvation structure. This solvation structure not only enhances de-solvation kinetics but also forms stable anion-derived interfaces at both electrodes, thereby maintaining electrode stability and preventing free solvent decomposition. Li-LiNi_0.8Co_0.1Mn_0.1O₂ (NCM811) cells using a strong Coulomb force electrolyte (SCE) designed based on this principle demonstrate superior rate performance (20C/120.8 mA h g⁻¹) and cycling stability (5C/1000 cycles). Notably, even at an ultra-low concentration of 0.1 M, Li-NCM811 cells utilizing the SCE exhibit good rate performance (5C/121.9 mA h g⁻¹) and stable cycling over 200 cycles at a cutoff voltage of 4.4 V. This approach provides a high-performance and cost-effective electrolyte solution for practical high-voltage LMB applications.