Title
Low-Cost Fluoride Source for Organic Liquid Electrolyte-Based Fluoride Shuttle Battery
Author
Asuman Celik Kucuk, Toshiro Yamanaka, Yuko Yokoyama and Takeshi Abe
Year
2021
Journal
Journal of the Electrochemical Society
Abstract
The effects of using low-cost inorganic fluoride salts (i.e., KF or NaF) as fluoride sources in fluoride shuttle batteries (FSBs) on the electrochemical compatibility of BiF3 electrodes are investigated herein. The preparation of electrolytes containing saturated KF or NaF and 0.5 M 4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)pyridine (DiOB-Py) in G4 is described. For Py/NaF/G4, the discharge and charge reactions of BiF3 were hindered because of the low solubility of NaF as well as the low ionic conductivity of the electrolyte. However, inductively coupled plasma mass spectrometry (ICP-MS) analysis revealed that the solubility of KF in Py/KF/G4 was moderate and the ionic conductivity of Py/KF/G4 was promising. Higher oxidation and reduction peaks observed in the cyclic voltammograms of Py/KF/G4 than those of Py/G4 and Py/NaF/G4 are attributed to the enhanced electrochemical activity of the former. Consequently, the BiF3/C nanocomposite electrode exhibits good cycling capability in Py/KF/G4, with initial discharge/charge capacities of 316/218 mAh g−1, respectively. Moreover, the ICP-MS and Raman spectroscopy analyses revealed that defluorination reactions of BiF3 occur via a direct desorption mechanism. Py/KF/G4 is the first effective electrolyte based on a low-cost inorganic salt. FSBs exhibit improved performance in Py/KF/G4 compared with CsF salt systems, which warrants further investigation.
Instrument
NRS-4500
Keywords
Liquid Electrolite, Fluoride, Battery, Raman Spectroscopy