Screening additive for stable solid electrolyte interphase in polymer lithium battery by coulometric titration time...

Area of Science:

• Materials Science
• Electrochemistry
• Battery Technology

Background:

• Solid electrolyte interphase (SEI) stability is crucial for solid-state polymer lithium metal battery performance.
• Characterizing the temporal evolution of SEI remains a significant challenge.
• Electrolyte additives can improve SEI quality but require effective evaluation methods.

Purpose of the Study:

• To evaluate the long-term stability of SEI in poly(ethylene oxide) (PEO)-based solid polymer electrolytes (SPEs) using various additives.
• To demonstrate the efficacy of coulometric titration time analysis (CTTA) for screening SEI-stabilizing additives.
• To identify optimal additives for enhancing the performance and lifespan of polymer-based solid-state batteries.

Main Methods:

• Utilized coulometric titration time analysis (CTTA), a sensitive electrochemical technique.
• Systematically screened a range of additives including ion-conductive fillers, inert fillers, plasticizers, and lithium salts.
• Investigated the effects of lithium difluoro(oxalato)borate (LiDFOB) on SEI formation and stability in PEO-based SPEs.

Main Results:

• LiDFOB preferentially decomposes at the lithium anode, forming a thin, inorganic-rich passivation SEI layer.
• This LiDFOB-induced SEI layer mitigates the degradation of both PEO and Lithium bis(trifluoromethanesulphonyl)imide (LiTFSI).
• Incorporation of LiDFOB extended the lithium consumption time by approximately 14-fold, indicating suppressed interfacial side reactions.

Conclusions:

• CTTA is a powerful diagnostic tool for screening interfacial-stabilizing additives for solid-state batteries.
• LiDFOB is a highly effective additive for enhancing SEI stability and battery performance.
• The study provides guidelines for designing long-life polymer-based solid-state batteries.