Electrolysis energy efficiency of highly concentrated FeCl[sub]2 solutions for power-to-solid energy storage technology
An electrochemical cycle for the grid energy storage in the redox potential of Fe involves the electrolysis of a highly concentrated aqueous FeCl2 solution yielding solid iron deposits. For the high overall energy efficiency of the cycle, it is crucial to maximize the energy efficiency of the electrolysis process. Here we present a study of the influence of electrolysis parameters on the energy efficiency of such electrolysis, performed in an industrial-type electrolyzer. We studied the conductivity of the FeCl2 solution as a function of concentration and temperature and correlated it with the electrolysis energy efficiency. The deviation from the correlation indicated an important contribution from the conductivity of the ion-exchange membrane. Another important studied parameter was the applied current density. We quantitatively showed how the contribution of the resistance polarization increases with the current density, causing a decrease in overall energy efficiency. The highest energy efficiency of 89 ± 3% was achieved using 2.5 mol L−1 FeCl2 solution at 70 °C and a current density of 0.1 kA m−2. In terms of the energy input per Fe mass, this means 1.88 Wh g−1. The limiting energy input per mass of the Fe deposit was found to be 1.76 Wh g−1.
2022
2022-02-16 14:09:27
1033
electrolysis, ferrous chloride, iron deposition, energy efficiency
Uroš
Luin
70
Matjaž
Valant
70
COBISS_ID
3
97710851
UDK
4
620.1/.2
ISSN pri članku
9
1432-8488
DOI
15
10.1007/s10008-022-05132-y
NUK URN
18
URN:SI:UNG:REP:MMKUVEZ5
s10008-022-05132-y.pdf
2088194
Predstavitvena datoteka
2022-02-16 14:11:19
RAZ_Luin_Uros_i2022.pdf
2108969
Predstavitvena datoteka
2022-03-23 08:45:47
0
Izvorni URL
2022-02-16 14:09:55