Fluoroborate ionic liquids as sodium battery electrolytes

Dale T. Duncan; Samantha L. Piper; Maria Forsyth; Douglas R. MacFarlane; Mega Kar

doi:10.1039/d3cp03694d

Fluoroborate ionic liquids as sodium battery electrolytes

Dale T. Duncan, Samantha L. Piper, Maria Forsyth, Douglas R. MacFarlane, Mega Kar

School of Chemistry

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

3 Citations (Scopus)

Abstract

High-voltage sodium batteries are an appealing solution for economical energy storage applications. Currently available electrolyte materials have seen limited success in such applications therefore the identification of high-performing and safer alternatives is urgently required. Herein we synthesise six novel ionic liquids derived from two fluoroborate anions which have shown great promise in recent battery literature. This study reports for the first time the electrochemically applicable room-temperature ionic liquid (RTIL) N-ethyl-N,N,N-tris(2-(2-methoxyethoxy)ethyl)ammonium (tetrakis)hexafluoroisopropoxy borate ([N_2(2O2O1)3][B(hfip)₄]). The RTIL shows promising physical properties with a very low glass-transition at −73 °C and low viscosity. The RTIL exhibits an electrochemical window of 5.3 V on a glassy carbon substrate which enables high stability electrochemical cycling of sodium in a 3-electrode system. Of particular note is the strong passivation behaviour of [N_2(2O2O1)3][B(hfip)₄] on aluminium current-collector foil at potentials as high as 7 V (vs. Na⁺/Na) which is further improved with the addition of 50 mol% Na[FSI]. This study shows [B(hfip)₄]⁻ ionic liquids have the desired physical and electrochemical properties for high-voltage sodium electrolytes.

Original language	English
Pages (from-to)	27718-27730
Number of pages	13
Journal	Physical Chemistry Chemical Physics
Volume	25
Issue number	40
DOIs	https://doi.org/10.1039/d3cp03694d
Publication status	Published - 10 Oct 2023

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10.1039/d3cp03694d

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title = "Fluoroborate ionic liquids as sodium battery electrolytes",

abstract = "High-voltage sodium batteries are an appealing solution for economical energy storage applications. Currently available electrolyte materials have seen limited success in such applications therefore the identification of high-performing and safer alternatives is urgently required. Herein we synthesise six novel ionic liquids derived from two fluoroborate anions which have shown great promise in recent battery literature. This study reports for the first time the electrochemically applicable room-temperature ionic liquid (RTIL) N-ethyl-N,N,N-tris(2-(2-methoxyethoxy)ethyl)ammonium (tetrakis)hexafluoroisopropoxy borate ([N2(2O2O1)3][B(hfip)4]). The RTIL shows promising physical properties with a very low glass-transition at −73 °C and low viscosity. The RTIL exhibits an electrochemical window of 5.3 V on a glassy carbon substrate which enables high stability electrochemical cycling of sodium in a 3-electrode system. Of particular note is the strong passivation behaviour of [N2(2O2O1)3][B(hfip)4] on aluminium current-collector foil at potentials as high as 7 V (vs. Na+/Na) which is further improved with the addition of 50 mol% Na[FSI]. This study shows [B(hfip)4]− ionic liquids have the desired physical and electrochemical properties for high-voltage sodium electrolytes.",

author = "Duncan, {Dale T.} and Piper, {Samantha L.} and Maria Forsyth and MacFarlane, {Douglas R.} and Mega Kar",

note = "Funding Information: The authors acknowledge the Australian Research Council funded StorEnergy Industrial Transformation Training Centre (IC180100049) for financial support. The authors also thank Darcy Simondson-Tammer and Dr Cuong Nguyen for their assistance with analysis. Publisher Copyright: {\textcopyright} 2023 The Royal Society of Chemistry.",

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AU - Duncan, Dale T.

AU - Piper, Samantha L.

AU - Forsyth, Maria

AU - MacFarlane, Douglas R.

AU - Kar, Mega

N1 - Funding Information: The authors acknowledge the Australian Research Council funded StorEnergy Industrial Transformation Training Centre (IC180100049) for financial support. The authors also thank Darcy Simondson-Tammer and Dr Cuong Nguyen for their assistance with analysis. Publisher Copyright: © 2023 The Royal Society of Chemistry.

PY - 2023/10/10

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N2 - High-voltage sodium batteries are an appealing solution for economical energy storage applications. Currently available electrolyte materials have seen limited success in such applications therefore the identification of high-performing and safer alternatives is urgently required. Herein we synthesise six novel ionic liquids derived from two fluoroborate anions which have shown great promise in recent battery literature. This study reports for the first time the electrochemically applicable room-temperature ionic liquid (RTIL) N-ethyl-N,N,N-tris(2-(2-methoxyethoxy)ethyl)ammonium (tetrakis)hexafluoroisopropoxy borate ([N2(2O2O1)3][B(hfip)4]). The RTIL shows promising physical properties with a very low glass-transition at −73 °C and low viscosity. The RTIL exhibits an electrochemical window of 5.3 V on a glassy carbon substrate which enables high stability electrochemical cycling of sodium in a 3-electrode system. Of particular note is the strong passivation behaviour of [N2(2O2O1)3][B(hfip)4] on aluminium current-collector foil at potentials as high as 7 V (vs. Na+/Na) which is further improved with the addition of 50 mol% Na[FSI]. This study shows [B(hfip)4]− ionic liquids have the desired physical and electrochemical properties for high-voltage sodium electrolytes.

AB - High-voltage sodium batteries are an appealing solution for economical energy storage applications. Currently available electrolyte materials have seen limited success in such applications therefore the identification of high-performing and safer alternatives is urgently required. Herein we synthesise six novel ionic liquids derived from two fluoroborate anions which have shown great promise in recent battery literature. This study reports for the first time the electrochemically applicable room-temperature ionic liquid (RTIL) N-ethyl-N,N,N-tris(2-(2-methoxyethoxy)ethyl)ammonium (tetrakis)hexafluoroisopropoxy borate ([N2(2O2O1)3][B(hfip)4]). The RTIL shows promising physical properties with a very low glass-transition at −73 °C and low viscosity. The RTIL exhibits an electrochemical window of 5.3 V on a glassy carbon substrate which enables high stability electrochemical cycling of sodium in a 3-electrode system. Of particular note is the strong passivation behaviour of [N2(2O2O1)3][B(hfip)4] on aluminium current-collector foil at potentials as high as 7 V (vs. Na+/Na) which is further improved with the addition of 50 mol% Na[FSI]. This study shows [B(hfip)4]− ionic liquids have the desired physical and electrochemical properties for high-voltage sodium electrolytes.

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Fluoroborate ionic liquids as sodium battery electrolytes

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ARC Training Centre for Future Energy Storage Technologies

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Fluoroborate ionic liquids as sodium battery electrolytes

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