Tetramethylurea dimer/lithium salt-based deep eutectics as a novel class of eutectic electrolytes

Ogawa, Hideyuki; Sato, Yugo; Mori, Hideharu

doi:10.1039/d1qm01174j

“…DEEs recently have been applied to Li‐ion batteries using lithium salts and organic components based on ureas, acetamides, sulfonamides, nitriles, and organosulfides [3,6–7] . One common characteristic between these eutectic materials is the intermolecular interaction of Li + to either O or N atoms in the organic compounds, which results in the deep eutectic effect [8] . Hydrogen bonding also has been shown to play a role in initiating the deep eutectic effect if both hydrogen bond donors and acceptors are present [9] .…”

Section: Introductionmentioning

confidence: 99%

“…[3,[6][7] One common characteristic between these eutectic materials is the intermolecular interaction of Li + to either O or N atoms in the organic compounds, which results in the deep eutectic effect. [8] Hydrogen bonding also has been shown to play a role in initiating the deep eutectic effect if both hydrogen bond donors and acceptors are present. [9] While research into lithium deep eutectics has been carried out, the field is still in its infancy and additional research can provide an unique pathway enhancement of Li-ion battery technologies.…”

Section: Introductionmentioning

confidence: 99%

Methyl Carbamate‐Lithium Salt Deep Eutectic Electrolyte for Lithium‐Ion Batteries

Hardin

¹

,

Duca

²

,

Imel

³

et al. 2022

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Deep eutectic electrolytes (DEEs) represent a burgeoning field in electrolytes for energy storage applications. Compared to the more conventionally studied Li‐ion electrolyte systems, these electrolytes offer numerous advantages, such as high ion concentration, costs, lower temperature operation, and safety. In this work, the formation of a novel eutectic electrolyte based on lithium salts and methyl carbamate was reported. These DEEs were formed via mixing lithium salts and low‐cost methyl carbamate at ratios varying from 1 : 2 to 1 : 5 (mol:mol). The DEE formed from methyl carbamate and lithium hexafluorophosphate (LiPF6) at a 1 : 5 molar ratio generated a 4V stability window and a 25 °C conductivity of up to 3.16E−3 S cm−1. The DEE formed from methyl carbamate and lithium bis(trifluoromethane)sulfonimide (LiTFSI) at a 1 : 5 molar ratio generated a 3.2 V stability window and a 25 °C conductivity of up to 2.87E−3 S cm−1. The LiPF6 DEE also demonstrated a discharge capacity of 128 mAh g−1after 50 cycles with 93 % discharge capacity retention at moderate cycling rates of 0.5C in a lithium titanate (LTO)/lithium iron phosphate (LFP) full cell. These results demonstrate the potential for methyl carbamate to generate eutectics from lithium salts and offer alternative electrolytes for use in low‐temperature Li‐ion battery applications.

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Li−N Interaction Induced Deep Eutectic Gel Polymer Electrolyte for High Performance Lithium‐Metal Batteries

Pei

¹

,

Li

²

,

Ou

³

et al. 2022

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As emerging eutectic mixtures, deep eutectic electrolytes (DEEs) show unique properties for Li-metal batteries (LMBs). However, the limited choice and inferior electrode compatibility hinder their further development in LMBs. Herein, we report a new 1,2dimethylimidazole (DMIm)-based deep eutectic gel polymer electrolyte induced by LiÀ N interaction. We demonstrate that incorporating electron-withdrawing polyvinylidene difluoride (PVDF) polymer into the DMIm-based DEE changes the coordination environment of Li + ions, leading to a high transference number of Li + ions (0.65) and superior interface stability between the electrolyte and Li anode. The deep eutectic gel polymer electrolyte exhibits excellent non-flammability, high ionic conductivity (1.67 mS cm À 1 at 30 °C), and high oxidation voltage (up to 4.35 V vs. Li/Li + ). The Li j j LFP cell based on the newly developed deep eutectic gel polymer electrolyte can achieve superior long-term cycling stability at a wide range of rates.

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Li−N Interaction Induced Deep Eutectic Gel Polymer Electrolyte for High Performance Lithium‐Metal Batteries

Pei

¹

,

Li

²

,

Ou

³

et al. 2022

View full text Add to dashboard Cite

As emerging eutectic mixtures, deep eutectic electrolytes (DEEs) show unique properties for Li-metal batteries (LMBs). However, the limited choice and inferior electrode compatibility hinder their further development in LMBs. Herein, we report a new 1,2dimethylimidazole (DMIm)-based deep eutectic gel polymer electrolyte induced by LiÀ N interaction. We demonstrate that incorporating electron-withdrawing polyvinylidene difluoride (PVDF) polymer into the DMIm-based DEE changes the coordination environment of Li + ions, leading to a high transference number of Li + ions (0.65) and superior interface stability between the electrolyte and Li anode. The deep eutectic gel polymer electrolyte exhibits excellent non-flammability, high ionic conductivity (1.67 mS cm À 1 at 30 °C), and high oxidation voltage (up to 4.35 V vs. Li/Li + ). The Li j j LFP cell based on the newly developed deep eutectic gel polymer electrolyte can achieve superior long-term cycling stability at a wide range of rates.

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Tetramethylurea dimer/lithium salt-based deep eutectics as a novel class of eutectic electrolytes

Abstract: Graphical abstract of our work including structures of tetramethylurea (TMU) dimer and Li salts, and photographs and ion-conductivities of the resulting deep eutectic electrolytes.

Cited by 7 publications

References 37 publications

Methyl Carbamate‐Lithium Salt Deep Eutectic Electrolyte for Lithium‐Ion Batteries

Methyl Carbamate‐Lithium Salt Deep Eutectic Electrolyte for Lithium‐Ion Batteries

Li−N Interaction Induced Deep Eutectic Gel Polymer Electrolyte for High Performance Lithium‐Metal Batteries

Li−N Interaction Induced Deep Eutectic Gel Polymer Electrolyte for High Performance Lithium‐Metal Batteries

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