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Electronic Supporting Information (ESI) for:
Identifying the mechanism and impact of parasitic reactions occurring in
carbonaceous Seawater Battery cathodesWonsuk Leea, Jehee Parka, Jaehyun Parka, Yunseok Choia, Seok Ju Kanga and Youngsik Kim a, b, *
a School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), UNIST-gil 50, Ulsan, 44919, Republic of Korea
b Energy Materials and Devices Lab, 4TOONE Corporation, UNIST-gil 50, Ulsan, 44919, Republic of Korea
* Corresponding author: [email protected] (Y. Kim)
Electronic Supplementary Material (ESI) for Journal of Materials Chemistry A.This journal is © The Royal Society of Chemistry 2020
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Fig. S1 Photographs of (a) components of the experimental setup for seawater battery cell
performance evaluation, (b) pristine ACC, (c) 20mAh charged ACC and (d) 20mAh discharged
ACC.
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Fig. S2 EDS mapping images of (a) charged ACC showing fiber peeling along with oxygen species
on their surface and (b) discharged ACC showing CaCO3 crystallite surface precipitation.
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Fig. S3 Schematic illustration of (a) carbon dioxide circulation in seawater and (b) carbonic acid
equilibria according to pH.
Carbonic acid equilibria were plotted by using the following equations and dissociation constants
=[𝐶𝑂2]
[𝐻 + ]2
[𝐻 + ]2 + 𝐾𝑎2[𝐻 + ] + 𝐾𝑎1𝐾𝑎2
=[𝐻𝐶𝑂3‒ ]
[𝐻 + ]𝐾𝑎2
[𝐻 + ]2 + 𝐾𝑎2[𝐻 + ] + 𝐾𝑎1𝐾𝑎2
= [𝐶𝑂32 ‒ ]
𝐾𝑎1𝐾𝑎2
[𝐻 + ]2 + 𝐾𝑎2[𝐻 + ] + 𝐾𝑎1𝐾𝑎2
Where the fraction of each carbonic species can be expressed in terms of pH and the dissociation
constants given at atmospheric pressure, temperature of 25°C and a salinity of S=351, 2:
CO2 + H2O ↔ H + HCO3- ; Ka1 = 1.085×10-6
HCO3- ↔ H+ + CO3
2- ; Ka2 = 8.12×10-10
Reference
1. S. Bavarella, A. Brookes, A. Moore, P. Vale, G. Di Profio, E. Curcio, P. Hart, M. Pidou and E. J. McAdam, Journal of Membrane Science, 2020, 599, 117682.
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2. C. Mehrbach, C. Culberson, J. Hawley and R. Pytkowicx, Limnology and Oceanography, 1973, 18, 897-907.
Fig. S4 (a) Schematic illustration of the three-electrode cycle experiment setup showing the
configuration of the charge cathode / anode / discharge cathode and (b) its actual setup.
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Fig. S5 (a, b) SEM images and the inset photograph of ACC showing removal of CaCO3
precipitates after charging the pre-discharged cathode. (c) EDS mapping images of (b), showing
traces of CaCO3 after charging.
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Fig. S6 Pre-charging and pre-discharging voltage profiles of the ACC for 20mAh at a current
density of 0.5mA (0.25mAcm-2).