New LHCE Designs for Lithium Metal Batteries

Electrolyte is a very critical component in lithium metal batteries (LMBs). It is recognized that the solvation structure near the Li ion plays a crucial role in determining the solid-electrolyte-interphase (SEI) properties and thus the reversibility of Li plating and stripping. Localized high-concentration electrolytes (LHCEs) have been developed for lithium metal batteries (LMBs) to regulate lithium ion solvation and the resulting SEI composition. While this method improves cycling life, fluorinated diluents in LHCEs cause significant Li corrosion through chemical decomposition, reducing calendar life. In this talk, we propose an LHCE with hexafluoroisopropyl methyl ether (HFME) as the diluent and n-hexane as an additive. The n-hexane acts as a barrier in the expanded SEI, suppressing HFME-induced Li corrosion. Cells using n-hexane and an 8-hour rest after each charge demonstrate improved calendar life, with 80.8% retention after 160 cycles, compared to 6.0% after 46 cycles without hexane. This shows the benefits of inert hydrocarbons for improving both cycle and calendar life in LHCE-based LMBs.