the rock-solid battery technology

Our product combines an easy innovative fabrication method and uses a patented electrode formulation, making it possible to utilize the tremendous potential of iron. There is still nickel in our first nickel-iron batteries. But in terms of cost not more than there is lead in a lead-acid battery. The cycle life is already proven to be several times longer than lead-acid batteries and the energy density is 2-3 times greater. In future, we aim to replace the nickel for much cheaper variants (e.g. air electrodes)
The abundance, direct availability and global utilization of iron makes it ideally suited  as the affordable clean-energy storage material, enabling energy storage for everyone, everywhere. Just take a look around you, from building materials to your body, the world runs on iron!



New horizons for cost-effective energy storage arise with our focus on durability, recyclability and the use of low-cost abundant non-toxic materials. Even with the current dropping prices of Li-ion batteries we expect to be cheaper.


low-cost is our biggest advantage, clean energy is the consequence



Below our IRON-IC flooded NiFeS battery prototype is shown. This is the blueprint for our first 1 kWh pack, having a replaceable ‘circular economy’ design. Our novel iron-anode provides a solution to the drawbacks caused by the iron anode in the traditional Nickel-Iron system, originally developed by Thomas Edison. With our patented chemistry, envisioned rethinking electrode- and cell design and recycling possibilities we aim to achieve the lowest cost per stored kWh available.

Nickel-based electrodes have an astonishing lifetime thousands of cycles. We have achieved 1500 cycles on our iron electrodes. As nickel-iron batteries are known for their long lifetime and ability to cycle 10.000 times, our expectation is that with our novel production method we can bring our chemistry to those cycle life levels and maintain the improved charge-discharge kinetics.


  • In IRON-IC the I and C stands for Imperative Charge/discharge rates (<15 min.)
  • 100% Depth of Discharge without failure
  • 75% round trip efficiency
  • Lower the costs of production by our novel electrode production technique excluding the need of a substrate, the most expensive part of the electrode.
  • Using a case design that makes it more easy to recycle and replace all components that have degraded separately.
  • < 0.01€ / kWh for only our iron electrode


If you have an interesting application and want to explore a collaboration, don’t hesitate to contact us!


We are currently scaling our cells and optimize our scaling, cutting, pasting and sizing of the electrodes. We work towards cylindrical sealed nickel-iron batteries. We are also exploring less costly counter-electrodes to pair our anode with, looking into manganese and having air as our ultimate goal. With our current R&D efforts we are on our way to combine our achievements with its long cycle life promise but we are still having some burdens on the road. The self-discharge is currently >3% a day and should be understood and minimized. The Round Trip Efficiency is around 70% and can be increased. The efficiency loss occurs mainly because we form hydroxen and oxygen gas during charging. The eventual cylindrical cell design is expected to solve this.
Do not hesitate to contact us when you think you can help us or we can set-up a collaboration. For vacancies please click here.



about us


Thomas van Dijk, Msc.
CEO and Business Development
Thomas invented the chemistry and founded E-stone. He studied Physics in Amsterdam and Sustainable Energy Technology at the TUDelft and followed several business courses. He is charged to bring iron batteries to as many applications as possible.
Leon Sturkenboom, Msc.
COO and Product Development
Leon developed the innovative fabrication method of the electrodes E-Stone uses today and built the foundations of E-Stone. With an education in environmental sciences at Wageningen University and Energy sciences at the University of Utrecht, Leon ensures E-Stone combines environmentally-friendly materials with cost-effective scaling.

Soraya Hartogs
Lab Technician

Tom Tamboer
Lab Technician

Bart Sluis, BSc.
Chemical Engineer

Cristina Herrero Ponce, MSc.
Chemical Engineer

Stelios Kyprou, MEng.
Product Designer

Viktor Bikov, BSc.
Business Developer



Our laboratory and business office are located at Industrie Park Kleefse Waard as we are part of the Generation-E incubator, the energy hub of the Netherlands. Next to this location, analytical laboratory work is performed at the TUDelft to further characterize the working mechanisms of our invention.

advisory board

Percival Ventures

Henk van Groen (Strategy)
Leo Visser (Technology)
Joep Koopmans (Finance)
Cato Woudenberg (Marketing & Communications)


Kic Innoenergy

Jan Caris (Strategy, Technology, battery expertise)


Solar Applications 

Gustaaf Haan (Founder “De Zonnefabriek” – Strategy and applications)


We are always looking for motivated people, so if your profiles does not perfectly matches one of the below, please feel free to send an open application.


contact us

Westervoortsedijk 71-S
6827AV Arnhem
+31 614499551 (Thomas)