Unbound Potential (A Swiss startup develops a low-cost, membrane-free redox flow battery for renewable energy storage)

Unbound Potential, a Swiss energy storage startup founded in 2023, develops a low-cost membrane-free redox flow battery system for long-term energy storage.

Challenges: Store renewable energy at a low cost

By the end of2022, the world had about 1,185 GW of installed solar capacity and about 906 GW of installed wind capacity. In the last decade, solar power has grown by an average of 24% per year. In the first quarter of 2023, the US solar industry installed 6.1 GW of capacity, which is 47% more than in the first quarter of 2022. On the other hand, the average power of new wind turbines installed in the US in 2022 was 3.2 MW, which is 7% more than 2021.

As more and more solar cells and wind turbines are being installed, the ability to store this clean electricity would significantly increase the efficiency and reliability of these intermittent renewable energy sources.

Flow batteries use the movement of electrolytes to store and release electrical energy. A typical flow battery has two half-cells that are separated by a membrane. Each half-cell has an electrode and an electrolyte. The electrolytes, called anolyte and catholyte, contain the redox-active species dissolved in an aqueous or non-aqueous solvent. They are stored outside the battery. When the battery is charged or discharged, they flow through the half-cells in contact with the electrodes, thanks to external pumps. This is very different from lithium-ion batteries.

However, the high cost of flow battery systems has limited their application worldwide. The capital cost of flow batteries is around $800 per kilowatt-hour, which is more than twice that of lithium-ion batteries. The membrane of the flow batteries is one of the obstacles to the widespread commercialization of the battery because it is not only expensive, accounting for up to 40 % of the total cost, but also limit the battery’s performance and lifespan. Therefore, we need cheap, high-energy, and stable flow battery systems for long-term energy storage.

Unbound Potential Technology

Unbound Potential develops a low-cost rechargeable flow battery system without a membrane. Its flow battery utilizes the immiscibility of oil and aqueous redox electrolytes, which enables a membrane-free design that can significantly reduce the battery system’s total cost. Unbound Potential’s core technology is the design of the battery reactor that enables the flow of both electrolytes for efficient electrode cell dynamics.

How Unbound Potential battery works?

The membrane-free redox flow battery based on the immiscibility of redox electrolytes was reported for the first time in 2017. However, the energy density of this type of battery is only 22.5 Wh/L.

In 2022, researchers from the University of Maryland and East China University of Science and Technology reported a high-energy membrane-free flow battery. This battery uses an aqueous sodium chloride (NaCl) electrolyte and an organic solvent of tetrachloride (CCl₄). Because CCl₄ and aqueous NaCl electrolyte are immiscible, a membrane-free design is possible. The battery works by electrolyzing aqueous NaCl electrolyte and the as-produced chlorine gas (Cl₂) is extracted and stored in CCl₄. This flow battery has an energy efficiency of greater than 91% and a high energy density of 125.7 Wh/L.

Salgenx, an American startup founded in 2022, has disclosed its high-energy, membrane-free redox flow battery based on CCl₄ and aqueous NaCl immiscibility electrolytes. The core technology of Salgenx’s membrane-free flow battery is its innovative battery reactor with rotor discs. These rotor discs create a  vortex flow of both immiscible electrolytes for electrode cell dynamics. This enhances battery efficiency while providing a more robust and simple reaction with less parts.

Ubound Potential may use CCl₄ and aqueous NaCl immiscible electrolytes to achieve a membrane-free, high-energy redox flow battery. The company’s core technology is the battery reactor design that enables the flow of both immiscible electrolytes for efficient electrode cell dynamics.

Unbound Potential membrane-free redox flow battery system.
Unbound Potential membrane-free redox flow battery system.

Ubound Potential has not disclosed its flow battery reactor.  We notice that one of the Co-Founders, David P. Taylor, is a specialist in microfluidics, thermodynamics, and micro-fabrication. He has initiated the idea of a new type of membrane-free redox flow battery based on his research background. Ubound Potential’s redox flow battery reactor may have an innovative design of the flow channel and/or microstructured electrode. We will further update Unbound Potential’s technology.

Unbound Potential Battery Applications

Unbound Potential has partnered with Iqony who will use its flow battery systems for renewable energy storage. Iqony is a company that focuses on renewable energies and bridging technologies that can be used in a climate-neutral way.

Unbound Potential Products

Together with SPRIN-D, Unbound Potential is developing the first 500 W table-top demonstrator (TRL 4).

Unbound Potential Funding

Unbound Potential has raised a total of €1M in funding over a Grant round in Nov 2022.

Unbound Potential Founder

David P. Taylor, Anetta Platek-Mielczarek, Pier Giuseppe Rivano, and Federico Paratore are Co-Founder.

Unbound Potential CEO

David P. Taylor is CEO.

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