Asymmetric ether solvents for high-rate lithium metal battery electrolytes

Developing next-generation battery technologies will require significant advances in electrolyte design and optimization. Symmetric ether solvents have emerged as promising candidates for lithium metal batteries due to their stability against lithium metal and tunable bulk transport properties, but often suffer from slow redox kinetics at the interface. In this work, we systematically modify a commonly-used symmetric ether solvent (1,2-diethoxyethane) to understand how solvent asymmetry affects interfacial redox kinetics. Our experimental results show that asymmetric solvents can achieve significantly higher exchange current densities than their symmetric counterparts, indicating faster interfacial kinetics. To better understand the physical origins of this phenomenon, we studied the spatial and orientational distribution of asymmetric molecules near the interface through DFT calculations and all-atom classical molecular dynamics simulations. Overall, our findings give insight into the subtle interplay between solvent asymmetry and charge transfer kinetics, demonstrating a new strategy to design electrolytes suitable for applications requiring high power density.