Internship | Development of novel organic Redox Flow Battery materials and optimization

RFBs are currently finding their way to the market using different forms of vanadium as the agent to be oxidized and reduced, being expensive, toxic, and unsuitable for large-scale application. More environmentally benign systems are needed!



Education type

university (wo)


Internship and graduation project

Hours a week

Fulltime – 40


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What will be your role?

The increasing implementation of renewable energy systems, e.g. solar PV panels and wind, is hindered by the mismatch in supply and demand of the generated electricity. By storing the excess electric energy to be used on-demand, the overall sustainability of the energy system can be efficiently improved. The Energy Conversion & Storage research team of the TNO department of Sustainable Process & Energy Systems is working with other TNO departments and its partners on the development of compact energy storage and conversion reactors for buildings (electricity, heating and domestic hot water) and industry (large scale applications).

Redox flow batteries (RFBs) are a versatile means of storing electricity in chemicals, separating capacity and power by using a central reactor with separated modular storage tanks for a liquid containing the active compounds. RFBs are currently finding their way to the market using different forms of vanadium as the agent to be oxidized and reduced. Vanadium is expensive, toxic, and as yet unsuitable for large-scale applications and massive deployment. Current ongoing developments are to reach market introduction of more environmentally benign and cheaper redox flow batteries, a.o. by application of organic molecules.

In one of our ongoing projects, the goal is to enable RFBs with organic molecules from waste streams, potentially enabling cheap products with high storage density and proper performance characteristics. Although the system works as proven by our experiments, the current materials exhibit limited power and capacity and reaction kinetics are suboptimal. In order to optimize this, a new redox pair needs to be found that enables good kinetics, long-term operation, and sufficient storage density, while remaining cheap and environmentally benign. Upon success, this development stimulates the deployment of larger sizes and larger quantities of affordable and efficient RFBs in the near future.

The assignment
In a previous phase of the technology development, several proof-of-concept experiments were carried out in home-built reactors that showed the potential of the technology of organic molecules for RFBs. The next step is the targeted design of the redox couple, to optimize storage density, power potential and reversibility, while retaining low cost and non-toxicity. A thorough literature review needs to be done on the potential redox materials to meet these requirements. Upon identification of several potential redox couples from this initial task, some basic modelling should be carried out on these potential candidates for the given redox reactions for charge/discharge, as well as on potential bottlenecks and/or optimization of these redox pairs. Next, a proof-of-principle experiment needs to be developed and carried out (based on an existing cell design) and experiments need to be performed to validate the identified reactions for future application. In addition, the robustness of the technology needs to be taken into account, and a preliminary techno-economic evaluation should be carried out to see the potential for upscaling. Ultimately, the work needs to culminate in the design of a set of reactions suitable to carry out on a bigger scale, taking the dynamics of the process as well as up-scaling potential into account.

How do you want to contribute to tomorrow's world? How big can your impact be? Come and work at TNO and envision it.

What we expect from you

In general terms, graduation tasks include a thorough literature research, modeling and techno-economic evaluation of several innovative RFB couples, and finally performing some initial experiments. If possible, the intern will do the experimental part, but if not possible (due to Corona measures) the internship will be limited to a theoretical study. In the end of the graduation track, reporting of the obtained results through both an official TNO-report and an oral presentation for the SPES department (both in the English language) should take place. The student is expected to show a great responsibility and self-dependency during the project.

What you’ll get in return

You want to work on the precursor of your career; a work placement gives you an opportunity to take a good look at your prospective future employer. TNO goes a step further. It’s not just looking that interests us; you and your knowledge are essential to our innovation. That’s why we attach a great deal of value to your personal and professional development. You will, of course, be properly supervised during your work placement and be given the scope for you to get the best out of yourself. Naturally, we provide suitable work placement compensation.

TNO as an employer

Daily supervision will be done by a TNO-employee, and the SPES expertise and laboratories will be at the disposal of the intern.

The selection process

After the first CV selection, the application process will be conducted by the concerning department. TNO will provide a suitable internship agreement. If you have any questions about this vacancy, you can contact the contact person mentioned below.

Due to Covid-19 and the consequent uncertainties and restrictions, students who are not residing in the Netherlands may currently not be able to start an internship or graduation project at TNO.

Has this job opening sparked your interest?

Then please feel free to apply on this vacancy! For further questions don’t hesitate to contact us.


Contact: Ruud Cuypers
Phone number: +31 (0)88-86 62472

Note that applications via email and third party applications are not taken into consideration.


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