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High-voltage lithium-metal batteries (LMBs) with LiCoO 2 (LCO) as the cathode have high volumetric and gravimetric energy densities. However, it remains a challenge for stable cycling of LCO >4.5 V Li . Here we demonstrate that a rationally designed sulfonamide-based electrolyte can greatly improve the cycling stability at high voltages up to 4.7 V Li by stabilizing the electrode–electrolyte interfaces (EEIs) on both the Li-metal anode (LMA) and high-voltage LCO cathode. With the sulfonamide-based electrolyte, commercial LCO cathodes retain 89% and 85% of their capacities after 200 and 100 cycles under high charging voltages of 4.55 V Li and 4.6 V Li , respectively, significantly outperforming traditional carbonate-based electrolytes. The surface degradation, impedance growth, and detrimental side reactions in terms of gas evolution and Co dissolution are well suppressed. Our work demonstrates a promising strategy for designing new electrolytes to realize high-energy Li||LCO batteries.
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Single‐Solvent‐Based Electrolyte Enabling a High‐Voltage Lithium‐Metal Battery with Long Cycle Life
The application of Li-metal-anodes (LMA) can significantly improve the energy density of state-of-the-art lithium ion batteries. Lots of new electrolyte systems have been developed to form a stable solid electrolyte interphase (SEI) films, thereby achieving long-term cycle stability of LMA. Unfortunately, the common problem faced by these electrolytes is poor oxidation stability, which rarely supports the cycling of high-voltage Li-metal batteries (LMBs). In this work, a new single-component solvent dimethoxy(methyl)(3,3,3-trifluoropropyl) silane is proposed. The electrolyte composed of this solvent and 3 m LiFSI salt successfully supports the long-term cycle stability of limited-Li (50 µm)||high loading LiCoO2 (≈20 mg cm−2) cell at 4.6 V. Experiments and theoretical research results show that the outstanding performance of the electrolyte in high-voltage LMBs is mainly attributed to its unique solvation structures and its great ability to build a highly stable and robust interphase on the surface of LMA and high-voltage cathodes. Interestingly, this proposed electrolyte system builds a stable SEI film rich in LiF and Li3N on the surface of LMA by improving the two-electron reduction activity of FSI− without adding LiNO3, the well-known additive used for LMBs. The design idea of the proposed electrolyte can guide the development of high-voltage LMBs.
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- Award ID(s):
- 2211825
- PAR ID:
- 10427831
- Date Published:
- Journal Name:
- Advanced Energy Materials
- ISSN:
- 1614-6832
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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null (Ed.)Composite polymer electrolytes (CPEs) for solid-state Li metal batteries (SSLBs) still suffer from gradually increased interface resistance and unconstrained Li dendrite growth. Herein, we addressed the challenges by designing a LiF-rich inorganic solid-electrolyte interphase (SEI) through introducing a fluoride-salt concentrated interlayer on CPE film. The rigid and flexible CPE helps accommodate the volume change of electrodes, while the polymeric high-concentrated electrolyte (PHCE) surface-layer regulates Li-ion flux due to the formation of a stable LiF-rich SEI via anion reduction. The designed CPE-PHCE presents enhanced ionic conductivity and high oxidation stability of > 5.0V (vs. Li/Li+). What’s more, it dramatically reduces the interfacial resistance and achieves a high critical current density of 4.5 mA cm-2 for dendrite-free cycling. The SSLBs, fabricated with thin CPE-PHCE membrane (< 100 μm) and Co-free LiNiO2 cathode, exhibit exceptional electrochemical performance and long cycling stability. This approach of SEI design can also be applied to other types of batteries.more » « less
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- Free Publicly Accessible Full Text
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Accepted Manuscript
- Journal Article:
- https://doi.org/10.1002/aenm.202300918
