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 journalArticlepeer-review

    22 Citations (Scopus)

    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

    Bibliographical note

    Funding Information:
    This research was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology ( NRF-2017R1C1B2004307 ) and the mid- and long-term nuclear research and development program through the National Research Foundation of Korea ( NRF-2017M2A8A5014710 ) funded by the Korean Ministry of Science and ICT .

    Publisher Copyright:
    © 2019

    Keywords

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

    ASJC Scopus subject areas

    • General Chemical Engineering
    • Electrochemistry

    Fingerprint

    Dive into the research topics of 'Bis(oxalate)borate-containing electrolytes for high voltage electric double-layer capacitors: A comparative study'. Together they form a unique fingerprint.

    Cite this