Technology

In our lab we have proven our novel iron electrode to last more than 2500 cycles at higher temperatures, indicating we can confidently reach > 5000 cycles. Consisting of > 80% weight percentage iron and sulphur materials, the material bill of our electrodes is cheaper than any of the currently available battery electrodes.

Our USP’s are:

  • Lowest cost battery electrode in the world, both in CAPEX as Levelized Cost of Storage
  • Long lifetime
  • Easily recycle materials (iron, sulphur, carbon)
  • Aqueous electrolyte, being safe

Iron is only 1 electrode and a battery needs two. We have developed nickel-iron and iron-air prototypes to show two possible compelling products.

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 (especially sintered ones) have an astonishing lifetime of thousands of cycles. We have achieved more than 2500 full Depth of Discharge cycles on our iron electrodes versus a sintered electrode without any form of cooling, cycling 3-4 times a day. When cooling is applied in our field-prototypes, we expect to be able reach more than 5000 cycles. Nickel-iron batteries are known for their long lifetime and ability to cycle 10.000 times and our mission is to bring our novel production method and chemistry to those cycle life levels and maintain E-Stone’s improved charge-discharge kinetics.

  • Ability to charge and discharge in 15 min.
  • 100% Depth of Discharge without failure
  • 85% round trip efficiency for nickel-iron, 80% for iron-air
  • discharging to more than 575 mAh/g of iron @ 100 mA/g
  • Cycled > 2500 on nickel-iron and first successful iron-air cycles
  • 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 Levelized Cost of Storage

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. With our current R&D efforts we are on our way to combine our achievements with its long cycle life promise but we still have some challenges ahead. The self-discharge on our iron electrodes is currently 1% a day and should be further minimized and we should develop sealed cells, but with a coulombic efficiency of  >97% at more than 500 mAh/g or iron, we are confident this is a possible.