Abstract
Poly(ethylene oxide) (PEO) was the first lithium-ion conducting polymer developed 50 years ago and is still the most popular electrolyte matrix for solid-state lithium metal batteries. While many studies focus on increasing PEO ionic conductivity through doping with Li salts, little work has addressed using PEO and Li directly to generate Li+-conducting species in situ. Reaction between PEO and Li leads to ionic conductivity largely from Li+, in contrast to the case of added salts where the anion contribution dominates. Herein, electrochemical impedance spectroscopy shows the ionic conductivity of PEO thin films increases up to three orders of magnitude (from 10−7 to 10−4 S cm−1) when contacted with Li at elevated temperature. This is due to the reduction of ether bonds, which produces lithium alkoxides that are responsible for Li+ transport. Density functional theory analysis confirms this mechanism as thermodynamically favorable. X-ray photoelectron spectroscopy also shows the presence of organolithium species and Li2O, which are responsible for propagating reactions with PEO and forming an electronically insulating layer at the PEO–Li interface that halts further reaction, respectively. The underlying mechanisms of Li–polymer electrolyte reactions is clarified and new pathways for in situ Li+ doping of polymer electrolytes is presented.
| Original language | English |
|---|---|
| Article number | 2100142 |
| Journal | Advanced Energy and Sustainability Research |
| Volume | 3 |
| Issue number | 1 |
| DOIs | |
| State | Published - Jan 2022 |
| Externally published | Yes |
Bibliographical note
Funding Information:P.L. and M.J.C. contributed equally to this work. This work was funded by the U.S. Department of Energy and support from Tien Duong of the Office of Energy Efficiency and Renewable Energy Vehicle Technologies Program is gratefully acknowledged. Research was carried out at Argonne National Laboratory which is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under contract no. DE-AC02-06CH1135. The authors also acknowledge support from the Office of Science, Office of Basic Energy Sciences, Materials Sciences and Engineering Division, for the EIS work carried out at University of Chicago. Li e-beam evaporation and XPS measurements were carried out at the Electrochemical Discovery Laboratory, a Joint Center for Energy Storage Research facility at Argonne National Laboratory.
Funding Information:
P.L. and M.J.C. contributed equally to this work. This work was funded by the U.S. Department of Energy and support from Tien Duong of the Office of Energy Efficiency and Renewable Energy Vehicle Technologies Program is gratefully acknowledged. Research was carried out at Argonne National Laboratory which is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under contract no. DE‐AC02‐06CH1135. The authors also acknowledge support from the Office of Science, Office of Basic Energy Sciences, Materials Sciences and Engineering Division, for the EIS work carried out at University of Chicago. Li e‐beam evaporation and XPS measurements were carried out at the Electrochemical Discovery Laboratory, a Joint Center for Energy Storage Research facility at Argonne National Laboratory.
Publisher Copyright:
© 2021 The Authors. Advanced Energy and Sustainability Research published by Wiley-VCH GmbH.
Keywords
- in situ salt formation
- lithium interfacial reactivities
- lithium metal batteries
- poly(ethylene oxide)
- spectroscopy
- thin films