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Flexible and low-cost poly(ethylene oxide) (PEO)-based electrolytes are promising for all-solid-state Li-metal batteries because of their compatibility with a metallic lithium anode. However, the low room-temperature Li-ion conductivity of PEO solid electrolytes and severe lithium-dendrite growth limit their application in high-energy Li-metal batteries. Here we prepared a PEO/perovskite Li 3/8 Sr 7/16 Ta 3/4 Zr 1/4 O 3 composite electrolyte with a Li-ion conductivity of 5.4 × 10 −5 and 3.5 × 10 −4 S cm −1 at 25 and 45 °C, respectively; the strong interaction between the F − of TFSI − (bis-trifluoromethanesulfonimide) and the surface Ta 5+ of the perovskite improves the Li-ion transport at the PEO/perovskite interface. A symmetric Li/composite electrolyte/Li cell shows an excellent cyclability at a high current density up to 0.6 mA cm −2 . A solid electrolyte interphase layer formed in situ between the metallic lithium anode and the composite electrolyte suppresses lithium-dendrite formation and growth. All-solid-state Li|LiFePO 4 and high-voltage Li|LiNi 0.8 Mn 0.1 Co 0.1 O 2 batteries with the composite electrolyte have an impressive performance with high Coulombic efficiencies, small overpotentials, and good cycling stability.
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Electrolyte design implications of ion-pairing in low-temperature Li metal batteries
Lithium metal batteries are capable of pushing cell energy densities beyond what is currently achievable with commercial Li-ion cells and are the ideal technology for supplying power to electronic devices at low temperatures (≤−20 °C). To minimize the thermal management requirements of these devices, batteries capable of both charging and discharging at these temperatures are highly desirable. Here, we report >4 V Li metal full cell batteries (N/P = 2) capable of hundreds of stable cycles down to −40 °C, unambiguously enabled by the introduction of cation/anion pairs in the electrolyte. Via controlled experimental and computational investigations in electrolytes employing 1,2-dimethoxyethane as the solvating solvent, we observed distinct performance transitions in low temperature electrochemical performance, coincident with a shift in the Li + binding environment. The performance advantages of heavily ion-paired electrolytes were found to apply to both the cathode and anode, providing Li metal Coulombic efficiencies of 98.9, 98.5, and 96.9% at −20, −40, and −60 °C, respectively, while improving the oxidative stability in support of >4 V cathodes. This work reveals a strong correlation between ion-pairing and low-temperature performance while providing a viable route to Li metal full batteries cycling under extreme conditions.
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- Award ID(s):
- 2011924
- PAR ID:
- 10324289
- Date Published:
- Journal Name:
- Energy & Environmental Science
- Volume:
- 15
- Issue:
- 4
- ISSN:
- 1754-5692
- Page Range / eLocation ID:
- 1647 to 1658
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1039/D1EE03422G
