Influence of lithium salts on the combustion characteristics of dimethyl carbonate-based electrolytes using a wick combustion method

Guo, Feng; Ozaki, Yu; Nishimura, Kinya; Hashimoto, Nozomu; Fujita, Osamu

doi:10.1016/j.combustflame.2019.12.001

Cited by 17 publications

(5 citation statements)

References 48 publications

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“…31 TMP is used by some as a nonflammable additive in lithium-ion cells due to its high oxidation stability. [32][33][34] Therefore, it can also be ruled out as shuttle molecule. Lastly, the carbonate species at 11.8 min in electrolyte from the NMC811/AG cell at T F = 70 °C is highly unlikely to be the redox shuttle molecule since it is absent in LFP/AG cells.…”

Section: Resultsmentioning

confidence: 99%

Identification of Redox Shuttle Generated in LFP/Graphite and NMC811/Graphite Cells

Büchele

Adamson

Eldesoky

et al. 2023

J. Electrochem. Soc.

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Unwanted self-discharge of LFP/AG and NMC811/AG cells can be caused by in-situ generation of a redox shuttle molecule after formation at elevated temperature with common alkyl carbonate electrolyte. This study investigates the redox shuttle generation for several electrolyte additives, e.g., vinylene carbonate and lithium difluorophosphate, by measuring the additive reduction onset potential, first cycle inefficiency and gas evolution during formation at temperatures between 25 and 70°C. After formation, electrolyte is extracted from pouch cells for visual inspection and quantification of redox shuttle activity in coin cells by cyclic voltammetry. The redox shuttle molecule is identified by GC-MS and NMR as dimethyl terephthalate. It is generated in the absence of an effective SEI-forming additive, according to a proposed formation mechanism that requires residual water in the electrolyte, catalytic quantities of lithium methoxide generated at the negative electrode and, surprisingly, polyethylene terephthalate tape within the cell.

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Section: Resultsmentioning

confidence: 99%

Identification of Redox Shuttle Generated in LFP/Graphite and NMC811/Graphite Cells

Büchele

Adamson

Eldesoky

et al. 2023

J. Electrochem. Soc.

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“…High salt concentrations in LIBs exist mostly as ion pairs with low solvation number . These solutions protect the current collector against corrosion and provide a longer cycle life and improved safety. ,− Still, large salt concentrations lead to an amplified gas evolution, decreased ionic mobility and fluidity, and, most importantly, added cost and environmental concerns. − …”

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confidence: 99%

Low-Concentrated Lithium Hexafluorophosphate Ternary-based Electrolyte for a Reliable and Safe NMC/Graphite Lithium-Ion Battery

Nikiforidis

Raghibi

Sayegh

et al. 2021

J. Phys. Chem. Lett.

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Current commercial lithium-ion battery (LIB) electrolytes are heavily influenced by the cost, chemical instability, and thermal decomposition of the lithium hexafluorophosphate salt (LiPF6). This work studies the use of an unprecedently low Li salt concentration in a novel electrolyte, which shows equivalent capabilities to their commercial counterparts. Herein, the use of 0.1 M LiPF6 in a ternary solvent mixture of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and 1,1,2,2-tetrafluoroethyl 2,2,2-trifluoroethyl ether (TFE) (3EC/7EMC/20TFE, by weight) is investigated for the first time in LiNi1/3Mn1/3Co1/3O2 (NMC111)/graphite pouch cells. In solution, the Li+ transport number and diffusion are governed by the Grotthuss mechanism, with transport properties being independent of salt concentration. The proposed electrolyte operates in a wide temperature window (0–40 °C), is nonflammable (self-extinguishing under 2 s), and shows adequately fast wetting (4 s). When incorporated into the NMC/graphite pouch cell, it initially forms a solid electrolyte interphase (SEI) with minimal gas formation followed by a comparable battery performance to standard LiPF6 electrolytes, validated by a high specific capacity of 165 mAh g–1, Coulombic efficiencies of 99.3%, and capacity retention of 85% over 700 cycles.

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“…9,[18][19][20] Increased LiPF 6 concentrations have been shown to contribute to aluminum current collector passivation, 21 longer storage and cycle lifetimes, 2,9,12 and improved safety. 22,23 It has been shown that solvent molecules that accompany LiPF 6 in a solvation structure are those that react at electrode surfaces. [24][25][26] Over the last decade, considerable effort has focused on utilizing salts to improve the oxidation resistance of the electrolyte and has lead to the use of highly or super-concentrated electrolytes, 9,[27][28][29][30][31][32][33] well above 1-1.2 mol l −1 .…”

mentioning

confidence: 99%

Accelerated Failure in Li[Ni_0.5Mn_0.3Co_0.2]O₂/Graphite Pouch Cells Due to Low LiPF₆ Concentration and Extended Time at High Voltage

Aiken

Harlow

Tingley

et al. 2020

J. Electrochem. Soc.

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Li[Ni0.5Mn0.3Co0.2]O2/graphite pouch cells were cycled using protocols that included 24 h spent at high voltage (≥ 4.3 V) under constant voltage or open circuit conditions to accelerate failure. Compared to traditional cycling, failure was reached up to 3.5 times faster. When this protocol was applied to cells containing low LiPF6 concentrations (≤ 0.4 M) failure was achieved up to 17.5 times faster than traditional cycling with normal LiPF6 concentrations. This represents a time improvement on the order of years and therefore can be used as a high-throughput screening method. Failure mechanisms for cells containing a range of LiPF6 concentrations undergoing these aggressive protocols were investigated using charge-discharge cycling, impedance spectroscopy (including symmetric cell analysis) and isothermal microcalorimetry. Long times at high voltage rapidly increase positive electrode impedance but do not seem to consume lithium inventory. The use of lower LiPF6 concentrations does not seem to introduce new failure mechanisms but makes cells less tolerant to positive electrode impedance growth. The utility of this method is demonstrated by screening cells with a variety of electrolyte additive combinations. Fewer than 3 months were required to distinguish cells containing 1% lithium difluorophospate as superior to cells with other additive combinations.

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Influence of lithium salts on the combustion characteristics of dimethyl carbonate-based electrolytes using a wick combustion method

Cited by 17 publications

References 48 publications

Identification of Redox Shuttle Generated in LFP/Graphite and NMC811/Graphite Cells

Identification of Redox Shuttle Generated in LFP/Graphite and NMC811/Graphite Cells

Low-Concentrated Lithium Hexafluorophosphate Ternary-based Electrolyte for a Reliable and Safe NMC/Graphite Lithium-Ion Battery

Accelerated Failure in Li[Ni_0.5Mn_0.3Co_0.2]O₂/Graphite Pouch Cells Due to Low LiPF₆ Concentration and Extended Time at High Voltage

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Influence of lithium salts on the combustion characteristics of dimethyl carbonate-based electrolytes using a wick combustion method

Cited by 17 publications

References 48 publications

Identification of Redox Shuttle Generated in LFP/Graphite and NMC811/Graphite Cells

Identification of Redox Shuttle Generated in LFP/Graphite and NMC811/Graphite Cells

Low-Concentrated Lithium Hexafluorophosphate Ternary-based Electrolyte for a Reliable and Safe NMC/Graphite Lithium-Ion Battery

Accelerated Failure in Li[Ni0.5Mn0.3Co0.2]O2/Graphite Pouch Cells Due to Low LiPF6 Concentration and Extended Time at High Voltage

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Product

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Accelerated Failure in Li[Ni_0.5Mn_0.3Co_0.2]O₂/Graphite Pouch Cells Due to Low LiPF₆ Concentration and Extended Time at High Voltage