Optimization of Electrolyte Composition to Suppress Al Corrosion in Localized High-Concentration Electrolytes｜青山慧伍｜Research Insights

要　旨: Electrolytes with LiFSI added as lithium salt have advantages such as high thermal stability and high cycle life performance at high temperatures. However, electrolytes with LiFSI have a problem of Al corrosion of a current collector of positive electrode due to the reaction of Al with FSI^– and free solvent molecules. To address this problem, there have been researches of suppressing Al corrosion by high-concentration electrolytes. In high-concentration electrolytes, interactions between Li⁺, FSI^– and solvents are enhanced leading to increasing ionic association and reducing free solvent molecules. On the other hand, poor rate performance with high-concentration electrolytes is true in most cases due to low ionic conductivity and high viscosity. In this study, localized high-concentration electrolytes with lower viscosity and better rate performance were investigated by diluting high-concentration electrolyte with a fluorinated ether solvent. We examined multiple ratios of electrolyte components such as solvents, a diluent, and LiFSI in localized high-concentration electrolytes and suppress Al corrosion by finding the ratio that enhances interactions between Li⁺, FSI^– and the solvents.

青山慧伍 / Keigo Aoyama

要　旨: We are promoting electrification towards carbon neutrality, since the evolution of batteries is indispensable, we are developing high energy, high power and long-life lithium-ion batteries.
While Ni-rich layered cathodes such as NCM811 have high capacity, the cycle life using NCM811 at high temperatures decrease. To overcome poor cycle performance, reported localized high concentration electrolytes (LHCE) which contains DMC solvent was adapted to our chemical system and evaluated. Although better cycle performance at high temperature was observed, the resistance of cells using the LHCE should be lowered toward practical application.
In this study, the types and concentrations of solvents were investigated for long-life and high-power battery.

Optimization of Electrolyte Composition to Suppress Al Corrosion in Localized High-Concentration Electrolytes