High Voltage Electrolyte Design Mediated by Advanced Solvation Chemistry Toward High Energy Density and Fast Charging Lithium-Ion Batteries

Electrolyte is critical for transporting lithium-ion (Li⁺) in lithium-ion batteries (LIBs). However, there is no universally applicable principle for designing an optimal electrolyte. In most cases, the design process relies on empirical experiences and is often treated as highly confidential proprietary information. Herein, a solvation structure-related model for the quantitative design of electrolytes is introduced, focusing on the principles of coordination chemistry. As a paradigmatic example, a high-voltage electrolyte (i.e., 4.5 V vs anode) aimed at achieving a high energy density and fast charging LIB, which is specifically composed of an emerging, well-constructed hybrid hard carbon-silicon/carbon-based anode, and lithium cobalt oxide cathode, is developed. Not only the functions of each electrolyte component at the molecular scale within the Li⁺ solvation structure are analyzed but also an interfacial model is introduced to elucidate their relationship with the battery performance. This study represents a pioneering effort in developing a methodology to guide electrolyte design, in which the mutual effects of the Li⁺ de-solvation process and solid electrolyte interface (SEI) on the electrode surface are explored concurrently to understand the root cause of superior performance. This innovative approach establishes a new paradigm in electrolyte design, providing valuable insights at the molecular level.