Affiliation:
1. Energy and Environmental Directorate Pacific Northwest National Laboratory Richland WA 99354 USA
2. Environmental and Molecular Sciences Laboratory Pacific Northwest National Laboratory Richland WA 99354 USA
3. Physical and Computational Sciences Directorate Pacific Northwest National Laboratory Richland WA 99354 USA
4. Department of Chemistry State University of New York at Binghamton Binghamton NY 13902 USA
Abstract
AbstractThe lifespan of lithium (Li) metal batteries (LMBs) can be greatly improved by the formation of inorganic‐rich electrode‐electrolyte interphases (EEIs) (including solid‐electrolyte interphase on anode and cathode‐electrolyte interphase on cathode). In this work, a localized high‐concentration electrolyte containing lithium bis(fluorosulfonyl)imide (LiFSI) salt, 1,2‐dimethoxyethane (DME) solvent and 1,2‐bis(1,1,2,2‐tetrafluoroethoxy)ethane (BTFEE) diluent is optimized. BTFEE is a fluorinated ether with weakly‐solvating ability for LiFSI so it also acts as a co‐solvent in this electrolyte. It can facilitate anion decomposition at electrode surfaces and promote the formation of more inorganic‐rich EEI layers. With an optimized molar ratio of LiFSI:DME:BTFEE = 1:1.15:3, LMBs with a high loading (4 mAh cm−2) lithium nickel manganese cobalt oxide (LiNi0.8 Mn0.1 Co0.1) cathode can retain 80% capacity in 470 cycles when cycled in a voltage range of 2.8–4.4 V. The fundamental understanding on the functionality of BTFEE revealed in this work provides new perspectives on the design of practical high‐energy density battery systems.
Funder
U.S. Department of Energy
Vehicle Technologies Office