Bis(oxalate)borate-containing electrolytes for high voltage electric double-layer capacitors

A comparative study

Hoai Van T. Nguyen, Sanghee Lee, Kyungwon Kwak, Kyung Koo Lee

Research output: Contribution to journalArticle

Abstract

This study reports a systematic investigation of electrolytes based on new salts consisting of various cations and the bis(oxalate)borate (BOB) anion for use in electrical double layer capacitors. The quaternary ammonium salts—tetraethylammonium tetrafluoroborate (TEABF4), spiro-(1,1ʹ)-bipyrrolidinium tetrafluoroborate (SBPBF4), 1,1-dimethylpyrrolidinium tetrafluoroborate (DMPBF4), tetraethylammonium bis(oxalato)borate (TEABOB), spiro-(1,1ʹ)-bipyrrolidinium bis(oxalato)borate (SBPBOB), and 1,1-dimethylpyrrolidinium bis(oxalato)borate (DMPBOB)—were successfully prepared in high purity and dissolved in acetonitrile (ACN) at a concentration of 1.0 M. The successful synthesis of the salts was confirmed by nuclear magnetic resonance, ultraviolet–visible, and Fourier-transform infrared spectroscopies. The physicochemical properties and electrochemical performance of the prepared electrolytes, namely, thermal stability, ionic conductivity, viscosity, electrochemical stability window, specific capacitance, and durability, were investigated. Compared to the BF4-containing electrolytes, the new electrolytes based on the BOB anion, particularly the DMPBOB salt, showed dramatically enhanced high-voltage performance at elevated temperature. Electrical double layer capacitors based on 1 M DMPBOB in ACN exhibited a capacitance retention of 55.9% and a coulombic efficiency of >99% after 2000 cycles at a working voltage of 4.0 V and 45 °C. Moreover, X-ray photoelectron spectroscopy suggested that a highly stable protective layer induced by the BOB-containing electrolyte was formed on the negative electrode of the capacitor, inhibiting acute electrolyte decomposition during the cycling test.

Original languageEnglish
Article number134649
JournalElectrochimica Acta
Volume321
DOIs
Publication statusPublished - 2019 Oct 20

Fingerprint

Borates
Oxalates
Electrolytes
Electric potential
Capacitors
Salts
Acetonitrile
Anions
Capacitance
Negative ions
Tetraethylammonium
Ionic conductivity
Ammonium Compounds
Fourier transform infrared spectroscopy
Supercapacitor
Cations
Durability
Thermodynamic stability
X ray photoelectron spectroscopy
Positive ions

Keywords

  • 1,1-Dimethylpyrrolidinium bis(oxalato)borate
  • Conductive salts
  • Electric double-layer capacitor
  • High working voltage

ASJC Scopus subject areas

  • Chemical Engineering(all)
  • Electrochemistry

Cite this

Bis(oxalate)borate-containing electrolytes for high voltage electric double-layer capacitors : A comparative study. / Nguyen, Hoai Van T.; Lee, Sanghee; Kwak, Kyungwon; Lee, Kyung Koo.

In: Electrochimica Acta, Vol. 321, 134649, 20.10.2019.

Research output: Contribution to journalArticle

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abstract = "This study reports a systematic investigation of electrolytes based on new salts consisting of various cations and the bis(oxalate)borate (BOB) anion for use in electrical double layer capacitors. The quaternary ammonium salts—tetraethylammonium tetrafluoroborate (TEABF4), spiro-(1,1ʹ)-bipyrrolidinium tetrafluoroborate (SBPBF4), 1,1-dimethylpyrrolidinium tetrafluoroborate (DMPBF4), tetraethylammonium bis(oxalato)borate (TEABOB), spiro-(1,1ʹ)-bipyrrolidinium bis(oxalato)borate (SBPBOB), and 1,1-dimethylpyrrolidinium bis(oxalato)borate (DMPBOB)—were successfully prepared in high purity and dissolved in acetonitrile (ACN) at a concentration of 1.0 M. The successful synthesis of the salts was confirmed by nuclear magnetic resonance, ultraviolet–visible, and Fourier-transform infrared spectroscopies. The physicochemical properties and electrochemical performance of the prepared electrolytes, namely, thermal stability, ionic conductivity, viscosity, electrochemical stability window, specific capacitance, and durability, were investigated. Compared to the BF4-containing electrolytes, the new electrolytes based on the BOB anion, particularly the DMPBOB salt, showed dramatically enhanced high-voltage performance at elevated temperature. Electrical double layer capacitors based on 1 M DMPBOB in ACN exhibited a capacitance retention of 55.9{\%} and a coulombic efficiency of >99{\%} after 2000 cycles at a working voltage of 4.0 V and 45 °C. Moreover, X-ray photoelectron spectroscopy suggested that a highly stable protective layer induced by the BOB-containing electrolyte was formed on the negative electrode of the capacitor, inhibiting acute electrolyte decomposition during the cycling test.",
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AB - This study reports a systematic investigation of electrolytes based on new salts consisting of various cations and the bis(oxalate)borate (BOB) anion for use in electrical double layer capacitors. The quaternary ammonium salts—tetraethylammonium tetrafluoroborate (TEABF4), spiro-(1,1ʹ)-bipyrrolidinium tetrafluoroborate (SBPBF4), 1,1-dimethylpyrrolidinium tetrafluoroborate (DMPBF4), tetraethylammonium bis(oxalato)borate (TEABOB), spiro-(1,1ʹ)-bipyrrolidinium bis(oxalato)borate (SBPBOB), and 1,1-dimethylpyrrolidinium bis(oxalato)borate (DMPBOB)—were successfully prepared in high purity and dissolved in acetonitrile (ACN) at a concentration of 1.0 M. The successful synthesis of the salts was confirmed by nuclear magnetic resonance, ultraviolet–visible, and Fourier-transform infrared spectroscopies. The physicochemical properties and electrochemical performance of the prepared electrolytes, namely, thermal stability, ionic conductivity, viscosity, electrochemical stability window, specific capacitance, and durability, were investigated. Compared to the BF4-containing electrolytes, the new electrolytes based on the BOB anion, particularly the DMPBOB salt, showed dramatically enhanced high-voltage performance at elevated temperature. Electrical double layer capacitors based on 1 M DMPBOB in ACN exhibited a capacitance retention of 55.9% and a coulombic efficiency of >99% after 2000 cycles at a working voltage of 4.0 V and 45 °C. Moreover, X-ray photoelectron spectroscopy suggested that a highly stable protective layer induced by the BOB-containing electrolyte was formed on the negative electrode of the capacitor, inhibiting acute electrolyte decomposition during the cycling test.

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