Towards an Open-Source Hardware Flow Battery

Kirk Smith

Flow Battery Research Collective

Daniel Fernández Pinto

Flow Battery Research Collective

Josh Hauser

Utrecht University/FAIR Battery Project

Sanli Faez

Utrecht University/FAIR Battery Project

October 16, 2024

Flow Battery Research Collective: Who are we?

A brand-new community of researchers, energy storage users, and enthusiasts who want to help develop and democratize technologies for affordable, sustainable energy storage

We are trying to build an open-source battery for storing solar and wind energy.

https://fbrc.dev

Our approach

  • Open-source hardware1: no patents, no licensing fees, free for commercial use

  • Cooperative, not competitive: trying to establish global community of contributors (eventually, users)

Why open-source?

  • Low barriers to entry = more iterations, with more brainpower, for lower cost
    (vs. a closed-source, private enterprise)

  • Open-source provides valuable economic benefits, or, it takes money + time to reinvent the wheel

    • in software, open-source provides annual demand-side value to society of $8.8 trillion (USD) (Hoffmann et al. [2024])
    • For €1 billion invested, €65 to 95 billion benefit to EU GDP (Blind et al. [2021])

Open-source energy hardware

French academia:

  • LAAS-CNRS lab creates open-source power electronics, commercializes them with open-source hardware company OwnTech (OwnTech Foundation [2024])
    L’objectif est de “développer globalement et fabriquer localement”

  • Ampère laboratory at INSA Lyon: embedded motor control, lead-acid charge controllers

Globally:

Why not a battery?

Our roadmap

What scale?

Redflow’s ZBM3, 3 kW / 10 kWh zinc-bromine flow battery [2022]

Rongke Power’s 200 MW/800 MWh vanadium flow battery in Dalian Roth et al. [2023]

More like this

Less like this

Can RFBs really offer this performance?

A qualitative, non-peer-reviewed comparison - assuming all technologies were manufactured at the same economies of scale

The reality

Distribution of large-scale battery storage installations in the United States as of 2022, by chemical composition
(https://www.statista.com/statistics/1135383/battery-storage-installations-power-capacity-chemistry/)

Current status: prototype benchtop cell

Exploded view of current design

Exploded view of the a prior cell design

Some initial cost-saving measures

Affordable membrane

2,520 EUR/m2 vs. 6 EUR/m2 (Ion Power GmbH and Amazon UK)

Affordable current collectors

1,477 EUR/m2 vs. 66 EUR/m2 (FuelCellStore and Amazon US)

No glovebox/inert gas requirements

We use buffers to mitigate the effects of ambient oxygen

Apartment chemistry/prototyping

Small batch run for a workshop

More info on the workshop and cell design here: https://fbrc.dev/posts/Flow4U-conference/

The chemistry

Our initial chemistry is zinc-iodide, but we plan to explore more varieties.

  • Negative Terminal (Anode): \(\ce{3Zn_{(s)} -> 3 Zn^2+ + 6e-}\)

  • Positive Terminal (Cathode): \(\ce{2I3- + 6e- -> 6I- }\)

  • Overall: \(\ce{3Zn_{(s)} + 2I3- -> 3Zn^2+ + 6I-}, E^\ominus = 1.298 V\)

  • Parasitic reaction: \(\ce{6I- + O2 + 2 H2O -> 2I3- + 4OH- }\)

  • Existing literature: [Weng et al. 2017; Xie et al. 2018; Chakraborty et al. 2021]

Why Zn/I?

  • Easy to source, low-cost reagents (vs. vanadium, for example)

  • Compatible with cheap microporous membranes, such as paper

  • Resistant to dendrites

  • No detectable hydrogen evolution (unlike all-iron systems)

  • Acceptable energy density (>20Wh/L)

  • No strong acids or bases needed

  • Low toxicity (but don’t drink it!)

Current performance: low concentration, 100 mAh/cm²

1 m \(\ce{ZnCl2}\), 2 m \(\ce{KI}\), \(\ce{KAc}\) buffer, 5 mL each side, photopaper separator, 30 mA/cm², 100 mAh/cm², over 5 days

Current performance: low concentration, 120 mAh/cm²

1 m \(\ce{ZnCl2}\), 2 m \(\ce{KI}\), \(\ce{KAc}\) buffer, 5 mL each side, photopaper separator, 30 mA/cm², 120 mAh/cm², same cell from last test, 6 days (11 total)

Current performance: medium concentration try 1

2 m \(\ce{ZnCl2}\), 4 m \(\ce{KI}\), \(\ce{KAc}\) buffer, 5 mL each side, photopaper separator, 30 mA/cm², 120 mAh/cm²

Current performance: medium concentration try 2

2 m \(\ce{ZnCl2}\), 4 m \(\ce{KI}\), 2m \(\ce{NH4Cl}\), 5 mL each side, Daramic AA-900 separator, nonconductive felt for Zn, 30 mA/cm², 300 mAh/cm²

All of that information in one place, editable

How to get involved?

  • Test your chemistry/membrane/electrode in our cell
    • Looking for a lab to test all-vanadium system for us for comparison purposes
    • also organic-ferrocyanide chemistry, since this is popular for startups
    • it can fit in a glovebox! Can be nonaqueous-compatible
  • Improve/extend documentation
  • Help design better flow fields, cell geometry, modeling, etc.—especially with large-format cell and stack!
  • Actively looking for grants/funding opportunities/consortiums

https://fbrc.dev

Acknowledgements

  • Josh Hauser, Sanli Faez & FAIR Battery team
  • Daniel Fernández Pinto, chief chemist
  • Conference organizers!
  • NLnet’s NGI0 Entrust fund

FAIR Battery

https://nlnet.nl/project/RedoxFlowBattery/

References

Journée d’Automne du GDR Redox Flow, Amiens, 16-17 Octobre 2024

Blind, K., Böhm, M., Grzegorzewska, P., et al. 2021. The impact of open source software and hardware on technological independence, competitiveness and innovation in the EU economy. Final Study Report. European Commission, Brussels, doi 10, 430161.
Chakraborty, M., Murcia-López, S., Morante, J.R., and Andreu, T. 2021. Structural Influence of the Anode Materials towards Efficient Zn Deposition/Dissolution in Aqueous Zn-Iodide Flow Batteries. Journal of The Electrochemical Society 168, 4, 040532.
Hoffmann, M., Nagle, F., and Zhou, Y. 2024. The Value of Open Source Software. SSRN Electronic Journal.
Irving, P., Cecil, R., and Yates, M.Z. 2021. MYSTAT: A compact potentiostat/galvanostat for general electrochemistry measurements. HardwareX 9, e00163.
OwnTech Foundation. 2024. OwnTech Foundation. https://www.owntech.org/.
Roth, C., Noack, J., and Skyllas-Kazacos, M., eds. 2023. Flow Batteries: From Fundamentals to Applications. Wiley.
Weng, G.-M., Li, Z., Cong, G., Zhou, Y., and Lu, Y.-C. 2017. Unlocking the capacity of iodide for high-energy-density zinc/polyiodide and lithium/polyiodide redox flow batteries. Energy & Environmental Science 10, 3, 735–741.
Xie, C., Zhang, H., Xu, W., Wang, W., and Li, X. 2018. A Long Cycle Life, Self-Healing ZincIodine Flow Battery with High Power Density. Angewandte Chemie 130, 35, 11341–11346.
ZBM3 battery redflow. 2022. https://redflow.com/zbm3-battery.