Molecular-Level Insights into Next-Generation Battery Electrolytes

Doctoral thesis, 2025

Unconventional electrolytes, especially highly concentrated electrolytes (HCEs) and deep eutectic electrolytes (DEEs), are emerging as promising candidates for a wide range of battery chemistries, including lithium-ion, lithium metal, and calcium batteries. Their tunability, non-volatility, and wide electrochemical stability windows make them attractive alternatives to conventional electrolytes. However, while the fundamental properties that make HCEs and DEEs attractive, such as their electrochemical stability and low melting points, are driven by molecular interactions, the interplay between these interactions and local structuring and their effects on macroscopic properties remains poorly understood.

To bridge this gap, we employ tight-binding and classical molecular dynamics simulations to investigate the local coordination environment, hydrogen bonding networks, and molecular-level ordering, especially in DEEs. By focusing on the interplay between hydrogen bond donors and different anion sizes and symmetries in hydrogen bond acceptors, we systematically explore how molecular interactions influence solvation structure and ion mobility. Our findings suggest that anion symmetry and size, together with hydrogen bonding strength, govern the solvation shell dynamics and overall diffusion behavior, impacting macroscopic transport properties.

Understanding these molecular-scale mechanisms is key to optimizing DEE formulations for different battery chemistries. This work provides fundamental insights into the structure and property relationships of DEEs, enabling their rational design for safer, more efficient energy storage technologies.