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Title: Studying voltage losses during discharge for biphenyl-sodium polysulfide organic redox flow batteries
Voltage losses during discharge have been quantitatively investigated in a coulombically balanced biphenyl (Bp)|sodium-polysulfide (Na2Sx) organic redox flow battery. The individual half-cell electrochemical impedance spectroscopy (EIS) response was studied using a flow cell with an in-situ sodium/sodium-ion reference electrode. The anode, consisting of Bp/Bp− couple, contributed approximately 58% of the total cell overpotential during discharge. Further investigation revealed that kinetic overpotential dominating both anode and cathode voltage losses during discharge. The EIS response for the sodium-polysulfide half-cell exhibits two semicircles at high and low frequencies. Since there is limited literature relating the high-frequency semicircle to a physical process, this work extends the investigation of cathode high-frequency EIS features using in-situ and ex-situ electrochemical diagnostic tools. The Bp Nyquist plot consisted of a single semi-circle due to its simpler redox reaction relative to the more complicated Na2Sx. Tafel analysis was used to calculate exchange current density values, with Bp having a lower exchange current density than Na2Sx. This finding explains the relatively higher Bp kinetic voltage loss as compared to Na2Sx.  more » « less
Award ID(s):
1933800
PAR ID:
10492642
Author(s) / Creator(s):
; ; ; ; ;
Publisher / Repository:
Elsevier
Date Published:
Journal Name:
Journal of Power Sources
Volume:
585
Issue:
C
ISSN:
0378-7753
Page Range / eLocation ID:
233538
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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