Influence of lithium salt anions on the interfacial properties of PEO-based solid-state electrolytes

The use of poly(ethylene oxide) (PEO)-based solid-state electrolytes have shown potential to improve both the energy density and safety performance of lithium-metal batteries. However, these electrolytes often form unstable interfaces with lithium metal anodes, compromising the durability and sustai...

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Main Authors: Yi-Min Wei, An Qiu, Jingchao Wang, Yu Gu, Jian-Feng Li
Format: Article
Language:English
Published: Elsevier 2025-08-01
Series:Electrochemistry Communications
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Online Access:http://www.sciencedirect.com/science/article/pii/S1388248125001183
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author Yi-Min Wei
An Qiu
Jingchao Wang
Yu Gu
Jian-Feng Li
author_facet Yi-Min Wei
An Qiu
Jingchao Wang
Yu Gu
Jian-Feng Li
author_sort Yi-Min Wei
collection DOAJ
description The use of poly(ethylene oxide) (PEO)-based solid-state electrolytes have shown potential to improve both the energy density and safety performance of lithium-metal batteries. However, these electrolytes often form unstable interfaces with lithium metal anodes, compromising the durability and sustained performance of solid-state lithium-metal batteries. In this study, three lithium salts, lithium (fluorosulfonyl) (trifluoromethanesulfonyl)imide (LiFTFSI), lithium bis(fluorosulfonyl)imide (LiFSI), and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), were each mixed in equimolar ratios with tetraethylene glycol dimethyl ether (G4) and introduced as a conductivity enhancer in PEO-based solid-state electrolytes. The effects of the lithium salt anions on the electrolyte properties were systematically investigated. Among the three, the fluorosulfonyl group was found to enhance ionic conductivity, while the trifluoromethanesulfonyl group improved thermal stability. Notably, the synergistic interaction between these two groups in LiFTFSI led to the formation of a stable solid-electrolyte interphase (SEI), characterized by a higher content of inorganic species and reduced organic components. As a result, LiFTFSI/G4-based solid-state electrolytes enabled stable cycling for 200 cycles at a 0.5C rate in LiFePO4-based solid-state lithium-metal batteries, achieving a capacity retention of 91 %. This study provides valuable insights into the optimization of high-efficiency solid-state lithium-metal batteries by elucidating the distinct roles of lithium salt anions.
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spelling doaj-art-37b4bd60ced74f7b887231146cc7ea402025-08-20T03:35:43ZengElsevierElectrochemistry Communications1388-24812025-08-0117710797910.1016/j.elecom.2025.107979Influence of lithium salt anions on the interfacial properties of PEO-based solid-state electrolytesYi-Min Wei0An Qiu1Jingchao Wang2Yu Gu3Jian-Feng Li421C Innovation Laboratory, Contemporary Amperex Technology Co. Limited, Ningde 352100, ChinaCollege of Chemistry and Chemical Engineering, State Key Laboratory of Physical Chemistry of Solid Surfaces, the MOE Key Laboratory of Spectrochemical Analysis & Instrumentation, College of Energy, Xiamen University, Xiamen 361005, China21C Innovation Laboratory, Contemporary Amperex Technology Co. Limited, Ningde 352100, China; Corresponding authors.College of Chemistry and Chemical Engineering, State Key Laboratory of Physical Chemistry of Solid Surfaces, the MOE Key Laboratory of Spectrochemical Analysis & Instrumentation, College of Energy, Xiamen University, Xiamen 361005, China; Corresponding authors.College of Chemistry and Chemical Engineering, State Key Laboratory of Physical Chemistry of Solid Surfaces, the MOE Key Laboratory of Spectrochemical Analysis & Instrumentation, College of Energy, Xiamen University, Xiamen 361005, China; Innovation Laboratory for Sciences and Technologies of Energy Materials of Fujian Province (IKKEM), Xiamen 361005, China; Corresponding author at: College of Chemistry and Chemical Engineering, State Key Laboratory of Physical Chemistry of Solid Surfaces, the MOE Key Laboratory of Spectrochemical Analysis & Instrumentation, College of Energy, Xiamen University, Xiamen 361005, China.The use of poly(ethylene oxide) (PEO)-based solid-state electrolytes have shown potential to improve both the energy density and safety performance of lithium-metal batteries. However, these electrolytes often form unstable interfaces with lithium metal anodes, compromising the durability and sustained performance of solid-state lithium-metal batteries. In this study, three lithium salts, lithium (fluorosulfonyl) (trifluoromethanesulfonyl)imide (LiFTFSI), lithium bis(fluorosulfonyl)imide (LiFSI), and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), were each mixed in equimolar ratios with tetraethylene glycol dimethyl ether (G4) and introduced as a conductivity enhancer in PEO-based solid-state electrolytes. The effects of the lithium salt anions on the electrolyte properties were systematically investigated. Among the three, the fluorosulfonyl group was found to enhance ionic conductivity, while the trifluoromethanesulfonyl group improved thermal stability. Notably, the synergistic interaction between these two groups in LiFTFSI led to the formation of a stable solid-electrolyte interphase (SEI), characterized by a higher content of inorganic species and reduced organic components. As a result, LiFTFSI/G4-based solid-state electrolytes enabled stable cycling for 200 cycles at a 0.5C rate in LiFePO4-based solid-state lithium-metal batteries, achieving a capacity retention of 91 %. This study provides valuable insights into the optimization of high-efficiency solid-state lithium-metal batteries by elucidating the distinct roles of lithium salt anions.http://www.sciencedirect.com/science/article/pii/S1388248125001183Solid-state lithium metal batteriesPEO-based solid-state electrolytesLithium salt anions
spellingShingle Yi-Min Wei
An Qiu
Jingchao Wang
Yu Gu
Jian-Feng Li
Influence of lithium salt anions on the interfacial properties of PEO-based solid-state electrolytes
Electrochemistry Communications
Solid-state lithium metal batteries
PEO-based solid-state electrolytes
Lithium salt anions
title Influence of lithium salt anions on the interfacial properties of PEO-based solid-state electrolytes
title_full Influence of lithium salt anions on the interfacial properties of PEO-based solid-state electrolytes
title_fullStr Influence of lithium salt anions on the interfacial properties of PEO-based solid-state electrolytes
title_full_unstemmed Influence of lithium salt anions on the interfacial properties of PEO-based solid-state electrolytes
title_short Influence of lithium salt anions on the interfacial properties of PEO-based solid-state electrolytes
title_sort influence of lithium salt anions on the interfacial properties of peo based solid state electrolytes
topic Solid-state lithium metal batteries
PEO-based solid-state electrolytes
Lithium salt anions
url http://www.sciencedirect.com/science/article/pii/S1388248125001183
work_keys_str_mv AT yiminwei influenceoflithiumsaltanionsontheinterfacialpropertiesofpeobasedsolidstateelectrolytes
AT anqiu influenceoflithiumsaltanionsontheinterfacialpropertiesofpeobasedsolidstateelectrolytes
AT jingchaowang influenceoflithiumsaltanionsontheinterfacialpropertiesofpeobasedsolidstateelectrolytes
AT yugu influenceoflithiumsaltanionsontheinterfacialpropertiesofpeobasedsolidstateelectrolytes
AT jianfengli influenceoflithiumsaltanionsontheinterfacialpropertiesofpeobasedsolidstateelectrolytes