Cambridge startup claims its electrolytes can triple flow battery energy density

Kodiaq Technologies is developing organic electrolytes for redox flow batteries that it claims could achieve 300% the energy density of vanadium-based alternatives.

The UK-based startup has developed an organic electrolyte that is currently able to store energy at up to 50 Wh per liter – exceeding typical vanadium-based electrolyte energy density – and has identified a development pathway to further increase energy density.

Unlike a lithium-ion battery, redox flow batteries store charge in a liquid electrolyte which is separated by a membrane. The molecules developed in Kodiaq Technologies are soluble in aqueous solutions and act as electron acceptors, meaning they can receive electrons from the battery’s electrode, stabilize them and store within electrolyte solution.

Kodiaq Technologies’ commercial proposition is based on offering a higher density, competitively priced electrolyte that can serve as a drop-in solution for vanadium redox flow batteries.

The Cambridge University scientists behind Kodiaq Technology told ESS News that their organic molecules are capable of storing two electrons per molecular unit, compared to one per unit in vanadium electrolytes, with even greater energy density possible in the future.

“We have enhanced the molecules which are currently able to collect two electrons per molecular unit, and they can be developed further to accommodate three, four or even more electrons,” explained Kamil Sokolowski, chief technology officer and co-founder of Kodiaq Technologies.

“The importance of that is that an increased number of electrons per unit can be directly translated into higher energy densities. In turn, storing more energy per unit volume in the battery delivers a much higher return of investment – up to seven-times higher for two-electron systems – compared with classical vanadium-based systems,” he said.

Kodiaq Technologies is able to achieve high energy density with its electrolytes by using pyridinium molecules, a class of molecules that can very readily take on at least one electron. Oren Scherman, chief science officer at Kodiaq and director of the Melville Laboratory at University of Cambridge told ESS News that decades of experience have informed the development of the company’s molecules.

“We’ve really looked at the experiences that I’ve had in the last two decades running a lab in supramolecular chemistry, and these electrolytes can come together without actually forming any covalent bonds.

“When molecules come together and form covalent bonds, they tend to crash out of solution. That’s one of the mechanisms we’ve invoked in the design of these molecules: they can come together and stay together, operate together, and, by doing so, they actually protect themselves from detrimental engagement with oxygen,” Scherman explained.

The ability to operate without interacting with oxygen is one of the key benefits, according to Kodiaq. An air-tolerant electrolyte can cope with a higher voltage, meaning higher energy density, allowing for more storage on a smaller footprint.

Kinetic performance of electrolyte molecules also has an impact on battery efficiency and, as Sokolowski explained, the faster kinetics and lower viscosity in Kodiaq’s electrolyte enable more rapid mass transport and electron-transfer reactions at the electrode.

“This type of chemistry is much faster regarding kinetics than other types of electrolytes, including vanadium and other organic electrolytes” Sokolowski said. “This provides a lot of room for better efficiency.”

The next steps for Kodiaq Technologies involve demonstrating capability to the wider energy storage industry while continuing to develop its electrolyte with a view to further increasing energy density.

Kodiaq Technologies has no plans to manufacture flow batteries but will instead work with manufacturing partners in the chemical industry to scale electrolyte production, which can then be sold to for use in redox flow batteries.

Manufacturing the Kodiaq electrolyte will not require sourcing any rare elements, such as vanadium, but instead will use feedstock already commonplace in the pharmaceutical industry.

Company chairman David Fyfe told ESS News the availability of ingredients for Kodiaq Technologies electrolyte should be welcomed by energy storage businesses looking to limit geopolitical exposure.

“People ought to heave a sigh of relief that they’re not spending hundreds of millions on a flow battery installation where an element that could constitute almost 50% of the cost of the battery is questionable in terms of availability,” Fyfe said.

The next steps for Kodiaq Technologies are well mapped out, according to Fyfe, who said plans are in place to demonstrate capability to the wider industry following a successful fundraising round in late 2025 saw the startup raise GBP 850,000 ($1.1 million).

“The feedback we were getting from a number of institutions was we needed to tick some boxes and more extensively measure key battery parameters,” said Fyfe, adding that work to verify roundtrip efficiency and degradation characteristics will be carried out in the next six months.

The Kodiaq Technologies chairman has experience with commercialization innovative tech. Fyfe previously built and led Cambridge Display Technology, which spun out of Cambridge University, and was chairman at perovskite solar cell maker Oxford PV until November 2018. Fyfe told ESS News he expects commercialization of Kodiaq Technologies will progress relatively quickly.

“I will be disappointed if we don’t make a first sale in 2028,” said Fyfe. “It’s the drop-in solution for the replacement of vanadium in existing redox flow battery installations and that gives us an opportunity to significantly shorten the normal development program.”