Lithium Bis(fluorosulfonyl)imide/Poly(ethylene oxide) Polymer Electrolyte for All Solid-State Li-S Cell

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Science

Background:

• Solid polymer electrolytes (SPEs) are crucial for developing safer and high-performance batteries.
• Lithium-sulfur (Li-S) batteries offer high theoretical energy density but face challenges with electrolyte stability and cycling performance.
• Lithium bis(fluorosulfonyl)imide (LiFSI) is an emerging salt for lithium-ion and lithium metal batteries.

Purpose of the Study:

• To investigate the potential of LiFSI-based SPEs as electrolyte material and binder for Li-S polymer cells.
• To evaluate the electrochemical performance and cycling stability of Li-S polymer cells utilizing LiFSI-based SPEs.
• To compare the performance of LiFSI-based SPEs with conventional LiTFSI-based SPEs in Li-S polymer cells.

Main Methods:

• Fabrication of solid polymer electrolytes using poly(ethylene oxide) (PEO) and LiFSI.
• Assembly of Li-S all solid polymer cells with the developed electrolytes.
• Electrochemical characterization including specific discharge capacity, areal capacity, rate capability, and cycling performance analysis.

Main Results:

• The LiFSI-based Li-S all solid polymer cells demonstrated a high specific discharge capacity of 800 mAh g_sulfur^-1 and an areal capacity of 0.5 mAh cm^-2.
• Good rate capability was observed for the LiFSI-based Li-S polymer cells.
• Significantly improved cycling performance was achieved with LiFSI-based SPEs compared to LiTFSI-based SPEs, attributed to enhanced Li anode/electrolyte interphase stability.

Conclusions:

• LiFSI-based SPEs are effective electrolyte materials and binders for Li-S polymer cells.
• The enhanced stability of the Li anode/electrolyte interphase in LiFSI-based SPEs leads to superior cycling performance.
• LiFSI-based SPEs show significant promise as attractive electrolyte materials for advanced solid-state Li-S batteries.