Pseudoconcentrated Electrolyte with High Ionic Conductivity and Stability Enables High-Voltage Lithium-Ion Battery Chemistry

Electrolytes play a decisive role in determining the energy density, cycling life, safety, and temperature adaptability of lithium-ion batteries or any advanced battery chemistries. Here a “pseudoconcentrated electrolyte” combining advantages of both concentrated and diluted electrolytes is described as a brand-new approach for high-performance lithium-ion batteries. By designing a heterogeneous liquid structure for an electrolyte, we made it possible for Li+ to form a solvation sheath structure that is only attainable in concentrated electrolytes while using a low salt concentration. Such a pseudoconcentrated electrolyte, with lithium bis­(trifluoromethanesulfonyl imide) as lithium salt and carbonates as solvents, demonstrates high electrochemical oxidation resistance and a high anticorrosion capability toward an Al current collector, which are usually the characteristics of concentrated electrolytes, as well as high ionic conductivity and low viscosity, which are only available from diluted electrolytes. Thus, this innovative approach provides a brand-new avenue to tailor electrolyte properties for advanced battery chemistry applications