An anion outer-regulated electrolyte allows rapid desolvation to enable high-voltage lithium metal batteries

Abstract

The harnessing of ion–solvent and solvent–solvent interactions has garnered extensive attention for the construction of anion-dominated solvation structures in high-voltage batteries. Although it is established that the macroscopic dragging effect can lower the desolvation energy, the dynamic mechanisms governing electron transfer in electrolytes of high-voltage batteries remain poorly understood. This deficiency hampers the ability to formulate high-performance electrolytes in a targeted and effective manner. In this study, we propose an anion outer-regulated electrolyte (AORE) that disrupts the electronic interactions between solvated anions and peripheral solvents to reconstruct the dynamic solvation structure and accelerate the desolvation process. Combining multispectral characterization and theoretical calculations, a deep understanding of the nature of the anionic drag effect during electron transfer is obtained, confirming that the AORE can significantly enhance the lithium-ion transference number (0.8) and ion conductivity (8.24 mS cm⁻¹), as well as the flame-retardant properties of the electrolyte. The LiCoO₂‖Li cell assembled from the AORE retains 90.41% of its capacity even after 600 cycles at a high voltage of 4.6 V, and the capacity loss of a pouch battery based on the electrolyte is only 8% after 100 cycles and can successfully provide take-off and hovering power for micro-unmanned aerial vehicles. This study provides a new paradigm for advanced electrolyte design through molecular charge engineering strategies.