I remotely attended the “Annual UK Flow Battery Network Symposium” organized by Profs Toghill and Sobrido of Lancaster Uni and QMUL, respectively. I attended this symposium a few times in the past during my PhD in the UK, and I took some notes on the talks that were given, and also gave a small plug for FBRC in the form of a “business slide” (though we are not a business).
Agenda
Polysulfide redox couples
StorTera-Strathclyde
Been curious about this company for a while. Dr. Edward Brightman of Stratchclyde talked about a development project they did with StorTera, a Scottish stratup. It’s a lithium polysulfide approach, he cited this paper from Yi Cui’s group [1] in his intro, below is a figure from the accepted manuscript:
One electrolyte reservoir, lithium metal anode, polysulfide system. Hybrid between lithium polysulfide battery and redox flow battery.
Bit curious about sub-Saharan energy storage development work with a relatively unproven tech?
Sulfur extremely low cost. Still need an organic solvent though (DMSO 😟) and additives
Did stakeholder interviews with local energy storage developers in sub-Saharan Africa, people are interested in lower-cost and maintainable option (who wouldn’t be?)
They want it to be optimized for remanufacture/repair and regional manufacture—cool! It’s not open-source though 🙈
Seems like a lot of diagnostic techniques needed, also special electrolyte additives. This was the academic collaborator though, unsure if all the Raman/impedance would be needed in the field.
I saw StorTera a few years ago, partly through Wikipedia since they seem to have sort of created their entirely own page, just without the name of the company: https://en.wikipedia.org/wiki/Alkali_sulfur_liquid_battery. I took a look at some of the patents and there seemed to be a lot of focus on injecting certain additives into the flow loop at certain times during the charging process, which sounds tricky to me.
A choice question from the audience, couldn’t really hear the answer online.
In sulfur chemistry, after a few cycles the sulfur is everywhere except where it should be. Do you see some sulfur deposition on the membrane/separator or even on the lithium side?
Comment from Dr. Georg Lieser
Paraphrasing from Alexander Quinn’s talk: Regenesys almost commercialized polysulfide-bromide flow batteries in early 2000’s but might’ve scaled up too fast. Technoeconomic modeling suggested 20-30% cheaper stack or improvement in kinetics could’ve made it viable. Reference electrodes for this system are nontrivial…
Schmalz-VisBlue partnership for stacks
Schmalz, a company that makes industrial vacuum technology, has a venture doing stack assembly, initially with the VisBlue company based in Portugal/Denmark: https://batteryindustry.net/redox-flow-battery-systems-schmalz-and-visblue-sign-framework-supply-agreement/
Also saw a different German joint venture:
EverFlow is a Saudi-German joined venture owned by Nusaned Investment (SABIC) and SCHMID Group with more than 10 years of experience in Redox-Flow-Battery technology and manufacturing. EverFlow operates R&D facilities in Freudenstadt, Germany, and is setting up a 3GWh Flow-Battery manufacturing plant in Jeddah, Saudi Arabia. EverFlow targets technological and market leadership for Large Scale Flow Battery Storage.
Further info (2020): https://www.energy-storage.news/schmid-jv-to-begin-building-3gwh-saudi-arabia-flow-battery-factory-this-year/
Dryfe Group / HalioGen Zn-Br membraneless, biphasic
Relying on salting-in/salting-out properties of highly concentrated electrolytes.
They have a “TFSI phase” - sounds expensive (lots of fluoride)?
Truly biphasic though!
Current performance:
So, a ways to go on power/current density, but a novel space to explore—membranes are a pain, not needing them would be nice. Viscosity and cost of TFSI-based phases, though. A cool approach, electrolyte optimization is a really interesting problem.
Dr. Josh J. Bailey - QUB / QUILL
They are working on a very similar project to FBRC! Improving repeatability of an open-source flow cell across different labs. Along with Hugh O’Conner, based on this great paper [2].
Working on Mk3 version this year, aiming to get thinner, closer to real cell thicknesses.
Are able to test liquid flow for 700h without leakage.
Did multi-institution study
Repeatability improves with
calibrating pumps
cutting electrodes accurately with punches
using a fresh membrane each test
Voltage efficiency is what varied the most between tests, they were able to get this down to under 0.5% it sounded like.
But across institutions, the utilization efficiency varied the most!Paper coming soon on this!
“Overpotentials lower when vessels have tank I/O on opposite sides”
Zinc-Nickel membraneless RFBs
Dr. David Trudgeon, Exeter Uni:
They are experimenting with additives/surfactants to improve Zn morphology. Sintered Ni cathode sounds expensive, and they state it clearly:
Hydrogen-Bromine RFB
Always nice to see concrete numbers to compare technologies.
No way I’d ever want to mess with both hydrogen and bromine at the same time, though. On the upside, H-Br has incredibly high power rates and good round-trip efficiencies—but, the stack components are not cheap, and there are real safety risks involved.
References
Citation
@online{smith2025,
author = {Smith, Kirk Pollard},
title = {Notes on {UK} {RFB} Conference},
date = {2025-01-27},
url = {https://dualpower.supply/posts/UKRFB-2025/},
doi = {10.59350/z315k-j4q46},
langid = {en}
}