Water as an Effective Additive for High-Energy-Density Na Metal Batteries? Studies in a Superconcentrated Ionic Liquid Electrolyte

Shammi A. Ferdousi; Matthias Hilder; Andrew Basile; Haijin Zhu; Luke A. O'Dell; Damien Saurel; Teofilo Rojo; Michel Armand; Maria Forsyth; Patrick C. Howlett

doi:10.1002/cssc.201802988

Water as an Effective Additive for High-Energy-Density Na Metal Batteries? Studies in a Superconcentrated Ionic Liquid Electrolyte

Shammi A. Ferdousi, Matthias Hilder, Andrew Basile, Haijin Zhu, Luke A. O'Dell, Damien Saurel, Teofilo Rojo, Michel Armand, Maria Forsyth, Patrick C. Howlett^*

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

35 Scopus citations

Abstract

The effect of water on the properties of superconcentrated sodium salt solutions in ionic liquids (ILs) was investigated to design electrolytes for sodium battery applications with water as an additive. Water was added to a 50 mol % solution of NaFSI [FSI=bis(fluorosulfonyl)imide] in the ionic liquid N-methyl-N-propylpyrrolidinium bis(fluorosulfonyl)imide (C₃mpyrFSI). Although the thermal properties (e.g., glass transition temperature) showed little dependence on the water content, the viscosity and, in particular, the ionic conductivity were strongly affected. The Na|Na symmetrical cell cycling performance was strongly dependent on the applied current density as well as on the water content. At higher current densities (1.0 mA cm⁻²) the polarization profiles showed a water dependence, suggesting that water was actively involved in the formation of an improved solid electrolyte interface layer (SEI) for high-water-content samples (1000–5000 ppm), resulting in improved long-term cycling stability. The initial impedance of cells cycled at 1.0 mA cm⁻² (measured after 20 cycles) was elevated after water addition, and large polarizations occured for the “wet” samples. However, with further cycling the wet cells began to exhibit lower polarization and improved stability compared to the “dry” sample. The Na|NaFePO₄ cell cycling performance was also demonstrated with minimal effect on the cell capacity, further highlighting the negligible activity of water in these electrolyte systems. In fact, reduced cell polarization and a more clearly defined charge profile were evident after water addition. The work shown here suggests that water may be used as a convenient and inexpensive additive for superconcentrated sodium IL electrolytes for improved device performance.

Original language	English
Pages (from-to)	1700-1711
Number of pages	12
Journal	ChemSusChem
Volume	12
Issue number	8
DOIs	https://doi.org/10.1002/cssc.201802988
State	Published - 23 Apr 2019
Externally published	Yes

Keywords

batteries
bis(fluorosulfonyl)imide
ionic liquids
sodium
water

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10.1002/cssc.201802988

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title = "Water as an Effective Additive for High-Energy-Density Na Metal Batteries? Studies in a Superconcentrated Ionic Liquid Electrolyte",

abstract = "The effect of water on the properties of superconcentrated sodium salt solutions in ionic liquids (ILs) was investigated to design electrolytes for sodium battery applications with water as an additive. Water was added to a 50 mol % solution of NaFSI [FSI=bis(fluorosulfonyl)imide] in the ionic liquid N-methyl-N-propylpyrrolidinium bis(fluorosulfonyl)imide (C3mpyrFSI). Although the thermal properties (e.g., glass transition temperature) showed little dependence on the water content, the viscosity and, in particular, the ionic conductivity were strongly affected. The Na|Na symmetrical cell cycling performance was strongly dependent on the applied current density as well as on the water content. At higher current densities (1.0 mA cm−2) the polarization profiles showed a water dependence, suggesting that water was actively involved in the formation of an improved solid electrolyte interface layer (SEI) for high-water-content samples (1000–5000 ppm), resulting in improved long-term cycling stability. The initial impedance of cells cycled at 1.0 mA cm−2 (measured after 20 cycles) was elevated after water addition, and large polarizations occured for the “wet” samples. However, with further cycling the wet cells began to exhibit lower polarization and improved stability compared to the “dry” sample. The Na|NaFePO4 cell cycling performance was also demonstrated with minimal effect on the cell capacity, further highlighting the negligible activity of water in these electrolyte systems. In fact, reduced cell polarization and a more clearly defined charge profile were evident after water addition. The work shown here suggests that water may be used as a convenient and inexpensive additive for superconcentrated sodium IL electrolytes for improved device performance.",

keywords = "batteries, bis(fluorosulfonyl)imide, ionic liquids, sodium, water",

author = "Ferdousi, {Shammi A.} and Matthias Hilder and Andrew Basile and Haijin Zhu and O'Dell, {Luke A.} and Damien Saurel and Teofilo Rojo and Michel Armand and Maria Forsyth and Howlett, {Patrick C.}",

note = "Publisher Copyright: {\textcopyright} 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim",

year = "2019",

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doi = "10.1002/cssc.201802988",

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TY - JOUR

T1 - Water as an Effective Additive for High-Energy-Density Na Metal Batteries? Studies in a Superconcentrated Ionic Liquid Electrolyte

AU - Ferdousi, Shammi A.

AU - Hilder, Matthias

AU - Basile, Andrew

AU - Zhu, Haijin

AU - O'Dell, Luke A.

AU - Saurel, Damien

AU - Rojo, Teofilo

AU - Armand, Michel

AU - Forsyth, Maria

AU - Howlett, Patrick C.

PY - 2019/4/23

Y1 - 2019/4/23

N2 - The effect of water on the properties of superconcentrated sodium salt solutions in ionic liquids (ILs) was investigated to design electrolytes for sodium battery applications with water as an additive. Water was added to a 50 mol % solution of NaFSI [FSI=bis(fluorosulfonyl)imide] in the ionic liquid N-methyl-N-propylpyrrolidinium bis(fluorosulfonyl)imide (C3mpyrFSI). Although the thermal properties (e.g., glass transition temperature) showed little dependence on the water content, the viscosity and, in particular, the ionic conductivity were strongly affected. The Na|Na symmetrical cell cycling performance was strongly dependent on the applied current density as well as on the water content. At higher current densities (1.0 mA cm−2) the polarization profiles showed a water dependence, suggesting that water was actively involved in the formation of an improved solid electrolyte interface layer (SEI) for high-water-content samples (1000–5000 ppm), resulting in improved long-term cycling stability. The initial impedance of cells cycled at 1.0 mA cm−2 (measured after 20 cycles) was elevated after water addition, and large polarizations occured for the “wet” samples. However, with further cycling the wet cells began to exhibit lower polarization and improved stability compared to the “dry” sample. The Na|NaFePO4 cell cycling performance was also demonstrated with minimal effect on the cell capacity, further highlighting the negligible activity of water in these electrolyte systems. In fact, reduced cell polarization and a more clearly defined charge profile were evident after water addition. The work shown here suggests that water may be used as a convenient and inexpensive additive for superconcentrated sodium IL electrolytes for improved device performance.

AB - The effect of water on the properties of superconcentrated sodium salt solutions in ionic liquids (ILs) was investigated to design electrolytes for sodium battery applications with water as an additive. Water was added to a 50 mol % solution of NaFSI [FSI=bis(fluorosulfonyl)imide] in the ionic liquid N-methyl-N-propylpyrrolidinium bis(fluorosulfonyl)imide (C3mpyrFSI). Although the thermal properties (e.g., glass transition temperature) showed little dependence on the water content, the viscosity and, in particular, the ionic conductivity were strongly affected. The Na|Na symmetrical cell cycling performance was strongly dependent on the applied current density as well as on the water content. At higher current densities (1.0 mA cm−2) the polarization profiles showed a water dependence, suggesting that water was actively involved in the formation of an improved solid electrolyte interface layer (SEI) for high-water-content samples (1000–5000 ppm), resulting in improved long-term cycling stability. The initial impedance of cells cycled at 1.0 mA cm−2 (measured after 20 cycles) was elevated after water addition, and large polarizations occured for the “wet” samples. However, with further cycling the wet cells began to exhibit lower polarization and improved stability compared to the “dry” sample. The Na|NaFePO4 cell cycling performance was also demonstrated with minimal effect on the cell capacity, further highlighting the negligible activity of water in these electrolyte systems. In fact, reduced cell polarization and a more clearly defined charge profile were evident after water addition. The work shown here suggests that water may be used as a convenient and inexpensive additive for superconcentrated sodium IL electrolytes for improved device performance.

KW - batteries

KW - bis(fluorosulfonyl)imide

KW - ionic liquids

KW - sodium

KW - water

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U2 - 10.1002/cssc.201802988

DO - 10.1002/cssc.201802988

M3 - 文章

C2 - 30740908

AN - SCOPUS:85063572719

SN - 1864-5631

VL - 12

SP - 1700

EP - 1711

JO - ChemSusChem

JF - ChemSusChem

IS - 8

ER -

Water as an Effective Additive for High-Energy-Density Na Metal Batteries? Studies in a Superconcentrated Ionic Liquid Electrolyte

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Keywords

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