Understanding the Electrochemical and Interfacial Behavior of Sulfolane based Electrolyte in LiNi0.5Mn1.5O4-Graphite Full-Cells

An ethylene carbonate-free electrolyte composed of 1 M lithium bis(fluorosulfonyl) imide (LiFSI) in sulfolane (SL) is studied here for LiNi0.5Mn1.5O4-graphite full-cells. An important focus on the evaluation of the anodic stability of the SL electrolyte and the passivation layers formed on LiNi0.5Mn1.5O4 (LNMO) and graphite is being analysed along with intermittent current interruption (ICI) technique to observe the resistance while cycling. The results show that the sulfolane electrolyte shows more degradation at higher potentials unlike previous reports which suggested higher oxidative stability. However, the passivation layers formed due to this electrolyte degradation prevents further degradation. The resistance measurements show that major resistance arises from the cathode. The pressure evolution during the formation cycles suggests that there is lower gas evolution with sulfolane electrolyte than in the conventional electrolyte. The study opens a new outlook on the sulfolane based electrolyte especially on its oxidative/anodic stability.

Automated summary

This study investigates a 1 M lithium bis(fluorosulfonyl) imide (LiFSI) electrolyte in sulfolane (SL) without ethylene carbonate for LiNi0.5Mn1.5O4-graphite full-cells. The focus is on evaluating the anodic stability of the SL electrolyte and the passivation layers formed on LiNi0.5Mn1.5O4 (LNMO) and graphite, along with resistance measurements using intermittent current interruption (ICI) technique during cycling. The results show that the sulfolane electrolyte degrades more at higher potentials, contradicting previous reports of higher oxidative stability. However, the formed passivation layers due to electrolyte degradation prevent further degradation. The study provides new insights into the oxidative/anodic stability of sulfolane-based electrolyte.