Si─O Molecular Engineering Enhances Cathode-Anode Interface Stability for High-Loading and High-Voltage Layered Cathode-Lithium Metal Batteries.

Abstract

Nickel-rich layered cathodes and lithium metal anode are promising for the next generation high-energy-density batteries. However, the unstable electrode-electrolyte interface induces structural degradation and battery failure under high-voltage and high-loading conditions. Herein, we report a fluorosilane-coupled electrolyte stabilizer with 1H, 1H, 2H, 2H-perfluorooctyltrimethoxysilane (PFOTMS), which presents higher adsorption energy with LiNi_0.8Co_0.1Mn_0.1O₂ cathode than solvents through the conjugation of Si─O bonds and therefore is oxidized on its surface to derive an interfacial layer rich in F and Si─O species. This architecture effectively stabilizes the cathode structure, suppresses transition metal migration, and promotes Li⁺ conduction and uniform deposition, which also suppresses the side reactions of electrolyte with both cathode and anode. This unique interfacial stabilization mechanism enables the Li||NCM811 battery to achieve a capacity retention rate of 80.8% after 600 cycles at 4.7 V. The Li||LiCoO₂ cell with a high mass loading of 20 mg cm^-2 achieves a remarkably high-capacity retention of 92.79% after 500 cycles at 4.4 V. This work proposes an interfacial stabilization that overcomes high-voltage limitations in practical nickel-rich cathode/lithium metal batteries.