TY - JOUR
T1 - An organic imidazolium derivative additive inducing fast and highly reversible redox reactions in zinc-bromine flow batteries
AU - Lee, Youngho
AU - Yun, Deokhee
AU - Park, Junyoung
AU - Hwang, Gyungmin
AU - Chung, Daewon
AU - Kim, Miae
AU - Jeon, Joonhyeon
N1 - Publisher Copyright:
© 2022 Elsevier B.V.
PY - 2022/11/1
Y1 - 2022/11/1
N2 - In zinc-bromine redox flow batteries (ZBBs), the weak molecular structure and stability of bromine-complexing agent (BCA) can sometime negatively affect battery's performance. To address this issue, this paper introduces a 1,2-dimethyl-3-ethylimidazolium bromide (DMEIm∙Br, C7H13BrN2), comprising planar molecular structure with strong molecular-polarizability and low steric hindrance. The effectiveness of the DMEIm∙Br is compared and verified with those of two popular BCAs through various electrochemical experiments including full-cell tests for 200 cycles. Experimental results show that the DMEIm∙Br significantly contributes to apparently enhancing reaction kinetics and reversibility of Zn2+/Zn(s) and Br−/Br2 redox couples by inducing highly reversible zinc-plating/stripping (by strong electrostatic shielding effect) and bromine-capture/release (along with strong bromine-binding strength) in anolyte and catholyte solutions, respectively. The superior chemical and electrochemical properties are clearly demonstrated by the fact that the DMEIm∙Br-supported solution in ZBBs exhibits 5.53 (24.19) and 7.29 (16.99) % higher current and voltaic efficiencies than the pristine solution at the temperature of 25 (60) °C, respectively. It also exhibits remarkably improved discharge-capacity retention of averagely 99.17% for 200 cycles along with a slight discharge-capacity loss of only 1.46% vs. 1st cycle at 200th cycle, even at the high temperature of 60 °C.
AB - In zinc-bromine redox flow batteries (ZBBs), the weak molecular structure and stability of bromine-complexing agent (BCA) can sometime negatively affect battery's performance. To address this issue, this paper introduces a 1,2-dimethyl-3-ethylimidazolium bromide (DMEIm∙Br, C7H13BrN2), comprising planar molecular structure with strong molecular-polarizability and low steric hindrance. The effectiveness of the DMEIm∙Br is compared and verified with those of two popular BCAs through various electrochemical experiments including full-cell tests for 200 cycles. Experimental results show that the DMEIm∙Br significantly contributes to apparently enhancing reaction kinetics and reversibility of Zn2+/Zn(s) and Br−/Br2 redox couples by inducing highly reversible zinc-plating/stripping (by strong electrostatic shielding effect) and bromine-capture/release (along with strong bromine-binding strength) in anolyte and catholyte solutions, respectively. The superior chemical and electrochemical properties are clearly demonstrated by the fact that the DMEIm∙Br-supported solution in ZBBs exhibits 5.53 (24.19) and 7.29 (16.99) % higher current and voltaic efficiencies than the pristine solution at the temperature of 25 (60) °C, respectively. It also exhibits remarkably improved discharge-capacity retention of averagely 99.17% for 200 cycles along with a slight discharge-capacity loss of only 1.46% vs. 1st cycle at 200th cycle, even at the high temperature of 60 °C.
KW - Bromine complexing agent
KW - Energy storage system
KW - Steric hindrance
KW - Zinc plating uniformity
KW - Zn–Br redox Flow battery
UR - http://www.scopus.com/inward/record.url?scp=85137046128&partnerID=8YFLogxK
U2 - 10.1016/j.jpowsour.2022.232007
DO - 10.1016/j.jpowsour.2022.232007
M3 - Article
AN - SCOPUS:85137046128
SN - 0378-7753
VL - 547
JO - Journal of Power Sources
JF - Journal of Power Sources
M1 - 232007
ER -