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
Novel electrolyte designs to further enhance the lithium (Li) metal battery cyclability are highly desirable. Here, fluorinated 1,6‐dimethoxyhexane (FDMH) is designed and synthesized as the solvent molecule to promote electrolyte stability with its prolonged –CF2– backbone. Meanwhile, 1,2‐dimethoxyethane is used as a co‐solvent to enable higher ionic conductivity and much reduced interfacial resistance. Combining the dual‐solvent system with 1
- PAR ID:
- 10450990
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Advanced Materials
- Volume:
- 33
- Issue:
- 25
- ISSN:
- 0935-9648
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
Abstract 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. -
Abstract Sulfurized polyacrylonitrile (SPAN) recently emerges as a promising cathode for high‐energy lithium (Li) metal batteries owing to its high capacity, extended cycle life, and liberty from costly transition metals. As the high capacities of both Li metal and SPAN lead to relatively small electrode weights, the weight and specific energy density of Li/SPAN batteries are particularly sensitive to electrolyte weight, highlighting the importance of minimizing electrolyte density. Besides, the large volume changes of Li metal anode and SPAN cathode require inorganic‐rich interphases that can guarantee intactness and protectivity throughout long cycles. This work addresses these crucial aspects with an electrolyte design where lightweight dibutyl ether (DBE) is used as a diluent for concentrated lithium bis(fluorosulfonyl)imide (LiFSI)‐triethyl phosphate (TEP) solution. The designed electrolyte (
d = 1.04 g mL−1) is 40%–50% lighter than conventional localized high‐concentration electrolytes (LHCEs), leading to 12%–20% extra energy density at the cell level. Besides, the use of DBE introduces substantial solvent‐diluent affinity, resulting in a unique solvation structure with strengthened capability to form favorable anion‐derived inorganic‐rich interphases, minimize electrolyte consumption, and improve cell cyclability. The electrolyte also exhibits low volatility and offers good protection to both Li metal anode and SPAN cathode under thermal abuse. -
Abstract Lithium‐ion batteries (LIBs) are increasingly encouraged to enhance their environmental friendliness and safety while maintaining optimal energy density and cost‐effectiveness. Although various electrolytes using greener and safer glyme solvents have been reported, the low charge voltage (usually lower than 4.0 V vs Li/Li+) restricts the energy density of LIBs. Herein, tetraglyme, a less‐toxic, non‐volatile, and non‐flammable ether solvent, is exploited to build safer and greener LIBs. It is demonstrated that ether electrolytes, at a standard salt concentration (1
m ), can be reversibly cycled to 4.5 V vs Li/Li+. Anchored with Boron‐rich cathode‐electrolyte interphase (CEI) and mitigated current collector corrosion, the LiNi0.8Mn0.1Co0.1O2(NMC811) cathode delivers competitive cyclability versus commercial carbonate electrolytes when charged to 4.5 V. Synchrotron spectroscopic and imaging analyses show that the tetraglyme electrolyte can sufficiently suppress the overcharge behavior associated with the high‐voltage electrolyte decomposition, which is advantageous over previously reported glyme electrolytes. The new electrolyte also enables minimal transition metal dissolution and deposition. NMC811||hard carbon full cell delivers excellent cycling stability at C/3 with a high average Coulombic efficiency of 99.77%. This work reports an oxidation‐resilient tetraglyme electrolyte with record‐high 4.5 V stability and enlightens further applications of glyme solvents for sustainable LIBs by designing Boron‐rich interphases. -
Abstract The practical application of lithium (Li) metal anode (LMA) is still hindered by non‐uniformity of solid electrolyte interphase (SEI), formation of “dead” Li, and continuous consumption of electrolyte although LMA has an ultrahigh theoretical specific capacity and a very low electrochemical redox potential. Herein, a facile protection strategy is reported for LMA using a double layer (DL) coating that consists of a polyethylene oxide (PEO)‐based bottom layer that is highly stable with LMA and promotes uniform ion flux, and a cross‐linked polymer‐based top layer that prevents solvation of PEO layer in electrolytes. Li deposited on DL‐coated Li (DL@Li) exhibits a smoother surface and much larger size than that deposited on bare Li. The LiF/Li2O enriched SEI layer generated by the salt decomposition on top of DL@Li further suppresses the side reactions between Li and electrolyte. Driven by the abovementioned advantageous features, the DL@Li||LiNi0.6Mn0.2Co0.2O2cells demonstrate capacity retention of 92.4% after 220 cycles at a current density of 2.1 mA cm–2(C/2 rate) and stability at a high charging current density of 6.9 mA cm–2(1.5 C rate). These results indicate that the DL protection is promising to overcome the rate limitation of LMAs and high energy‐density Li metal batteries.
-
Abstract A new concentrated ternary salt ether‐based electrolyte enables stable cycling of lithium metal battery (LMB) cells with high‐mass‐loading (13.8 mg cm−2, 2.5 mAh cm−2) NMC622 (LiNi0.6Co0.2Mn0.2O2) cathodes and 50 μm Li anodes. Termed “CETHER‐3,” this electrolyte is based on LiTFSI, LiDFOB, and LiBF4with 5 vol% fluorinated ethylene carbonate in 1,2‐dimethoxyethane. Commercial carbonate and state‐of‐the‐art binary salt ether electrolytes were also tested as baselines. With CETHER‐3, the electrochemical performance of the full‐cell battery is among the most favorably reported in terms of high‐voltage cycling stability. For example, LiNi
x Mny Co1–x –y O2(NMC)‐Li metal cells retain 80% capacity at 430 cycles with a 4.4 V cut‐off and 83% capacity at 100 cycles with a 4.5 V cut‐off (charge at C/5, discharge at C/2). According to simulation by density functional theory and molecular dynamics, this favorable performance is an outcome of enhanced coordination between Li+and the solvent/salt molecules. Combining advanced microscopy (high‐resolution transmission electron microscopy, scanning electron microscopy) and surface science (X‐ray photoelectron spectroscopy, time‐of‐fight secondary ion mass spectroscopy, Fourier‐transform infrared spectroscopy, Raman spectroscopy), it is demonstrated that a thinner and more stable cathode electrolyte interphase (CEI) and solid electrolyte interphase (SEI) are formed. The CEI is rich in lithium sulfide (Li2SO3), while the SEI is rich in Li3N and LiF. During cycling, the CEI/SEI suppresses both the deleterious transformation of the cathode R‐3m layered near‐surface structure into disordered rock salt and the growth of lithium metal dendrites.