.png?)
The Elestor solution
The choice of hydrogen and bromine
From all the different chemistries that theoretically could be used to design a flow battery, Elestor has selected hydrogen and bromine as active materials. This leads to several advantages. The choice of hydrogen and bromine was purely driven by Elestor’s mission to build a storage system with the lowest possible storage costs per MWh. While taking full advantage of the typical flow battery features, this mission cannot be accomplished without inexpensive chemistries.
Hydrogen and bromine are abundantly available on a global scale. The supply is not restricted to geographical availability, and cannot be dominated by a small group of suppliers, unlike, say, lithium, cobalt and vanadium.
The above factors add up to very low-priced active materials. Not only presently, but for decades to come, indeed, even when large volumes will be required for high volume production of hydrogen bromine flow batteries.
Another advantage of selecting hydrogen and bromine is that these enable a high power density [W/m2] as well as a high energy density [kWh/m3], both contributing to the reduction of storage costs per MWh.
The heart of all Elestor’s storage systems is the cell stack. This stack consists of a number of individual electrochemical cells, as shown above, connected in series.
Each membrane in this stack in contact with the electrolyte circuit, an aqueous solution of hydrogen bromide (HBr) and diatomic bromine (Br2), on one side. On the other side, each membrane is in contact with a hydrogen (H2) gas circuit. Both active materials circulate in a closed loop along their own respective side of the cell. The electrolyte (HBr/Br2 solution) and hydrogen (H2) circuits are separated by a proton-conductive membrane.
The hydrogen-bromine flow battery for a large scale integration of variable renewable electricity: State-of-the-art review
Y.A. Hugo, W. Kout, G. Dalessi
Elestor B.V., Utrechtseweg 310-H40, 6812 AR Arnhem, The Netherlands
Abstract
This article presents a state-of-the-art review of the hydrogen-bromine battery technology. The review aims to elaborate on the following topics: (1) the hydrogen-bromine flow battery, (2) the current status of technical developments on short-term and long-term cycling, and (3) the future direction for technology development.
Performance mapping of cation exchange membranes for hydrogen-bromine flow batteries for energy storage
Yohanes Antonius Hugo a, b, Wiebrand Kout b, Antoni Forner-Cuenca a, Zandrie Borneman a, c, Kitty Nijmeijer a, c, *
a Membrane Materials and Processes, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, PO Box 513, 5600MB Eindhoven, the Netherlands
b Elestor B.V., 6827 AV Arnhem, the Netherlands
c Dutch Institute for Fundamental Energy Research (DIFFER), P.O. Box 6336, 5600 HH Eindhoven, the Netherlands
⁎ Corresponding author. E-mail address: d.c.nijmeijer@tue.nl (K. Nijmeijer).
Abstract
Electricity storage is essential for the transition to sustainable energy sources. Hydrogen-bromine flow batteries (HBFBs) are promising cost-effective energy storage systems. In HBFBs, proton exchange membranes are required to separate the two reactive materials, enabling proton transport for charge balancing. In this paper, we present a comprehensive overview of the key properties and an experimental performance map of cation exchange membranes for HBFBs. Our study shows that membrane water uptake is an important property due to its strong correlation with membrane resistance and bromide species crossover. Long chain perfluorosulfonic acid (LC PFSA) membranes are shown to have a better power density–crossover tradeoff and a higher stability than other types of functionalized membranes. The good power density-crossover tradeoff of LC PFSA membranes is the result of the high level of separation of hydrophobic and hydrophilic domains in the membrane, leading to well-connected ionic pathways for proton transport. Reinforcement of long chain LC PFSA membranes further improves their tradeoff because it mechanically constrains the swelling (lower water uptake), resulting in a lower crossover but a similar peak power density. Consequently, reinforced LC PFSA membranes are the most promising option for HBFBs.
Low-cost wire-electrospun sulfonated poly(ether ether ketone)/poly (vinylidene fluoride) blend membranes for hydrogen-bromine flow batteries
Sanaz Abbasia, b, Antoni Forner-Cuencaa Wiebrand Koutb, Kitty Nijmeijer a, c, Zandrie Borneman a, c, *
a Membrane Materials and Processes, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, PO Box 513, 5600MB Eindhoven, the Netherlands
b Elestor B.V., 6827 AV Arnhem, the Netherlands
c Dutch Institute for Fundamental Energy Research (DIFFER), P.O. Box 6336, 5600 HH Eindhoven, the Netherlands
⁎ Corresponding author. Membrane Materials and Processes, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, P.O. Box 513, 5600 MB, Eindhoven, the Netherlands. E-mail address: Z.Borneman@tue.nl (Z. Borneman).
Abstract
Cost-effective dense membranes were developed by blending proton-conductive sulfonated poly(ether ether ketone) (SPEEK) with inert, mechanically stable poly(vinylidene fluoride) (PVDF) for hydrogen-bromine flow batteries (HBFBs). Wire-electrospinning followed by hot-pressing was employed to prepare dense membranes. Their properties and performance were compared to solution-cast membranes of similar composition and thickness. Electrospinning improved the ionic conductivity and bromine diffusion properties by providing interconnected ion-conductive SPEEK nanofiber pathways through a PVDF matrix. Relatively thin (~50–60 μm) electrospun membranes with a SPEEK/PVDF ratio (wt%/wt%) of 90/10 and 80/20 showed comparable Br3 − diffusion rates as the relatively thick and commercially available perfluorosulfonic acid (PFSA) membrane (~100 μm) at a 35%–42% lower proton conductivity. The latter can be attributed to the poorer ion conductivity of SPEEK compared to PFSA and the presence of PVDF. The HBFB single cell featured the best polarization behavior and ohmic area resistance with the electrospun membrane containing 80/20 (wt%/wt%) SPEEK/PVDF. However, the low thickness and insufficient chemical/mechanical stability of the ES 80/20 causes a rapid decay in the HBFB cycling performance. This study promotes a life-time comparison study between the low-cost wire- electrospun SPEEK/PVDF blend membranes (~€100 m− 2) and the typically used PFSA membranes (~€400 m− 2) for a long-term HBFB performance.