Dr Jiajun Cen
A pioneer in the clean energy sector and Forbes 30 Under 30, Dr Jiajun Cen is the CEO and Founder of climate tech company AQUABATTERY. The company makes rechargeable batteries that use saltwater as a storage medium instead of lithium, providing a safe, sustainable and low-cost alternative for energy storage.
Dr Jiajun Cen
A pioneer in the clean energy sector and Forbes 30 Under 30, Dr Jiajun Cen is the CEO and Founder of climate tech company AQUABATTERY. The company makes rechargeable batteries that use saltwater as a storage medium instead of lithium, providing a safe, sustainable and low-cost alternative for energy storage.
“I love the beauty of using mathematics to describe physics,” says Dr Jiajun Cen, known as JJ to his colleagues and friends, as he considers the path to his current position. The award-winning founder and CEO of AQUABATTERY, based in Amsterdam, says it’s more complicated than just a lifelong passion for science. “I love using engineering solutions to make an impact, which led me to the PhD I did at Imperial and later the startups I was involved in.”
Jiajun grew up in the Netherlands. From a very young age, he says he was excited to learn about technology. It wasn’t just science – it was innovation. “I was experimenting a lot,” he says. “You know, mixing chemicals just to see bubbles forming and playing with them. In high school, I built a magnetic levitation train with a track about two metres long – and I wrote software to drive it. There's a lot to be learnt by doing that – it isn't easy to stabilise something on a magnetic field. I think that was the beginning of my curiosity and learning by doing.”
Jiajun went on to study Applied Mathematics and Chemical Engineering, before starting at Imperial for a PhD in Chemical Engineering. But it wasn’t plain sailing.
Despite full scholarships awaiting him elsewhere, Jiajun was determined to go to Imperial, partly because of the strength of the Department of Chemical Engineering, and partly to stay relatively close to his family. He arrived with just £2,000 in cash, and almost all of it vanished on his very first day, swallowed by the rent of a tiny room he found online. So how did he survive?
I’m pretty relentless. When I lock on to a target, I just keep going.
Jiajun applied for funding, and sought help and advice from senior academics. Over the course of his PhD, he received 18 competitive scholarships, including from the Grantham Institute, the Natural Environment Research Council, and even the Burkett scholarship from the Department of Chemical Engineering for research excellence. He says that this time spent knocking on doors and seeking financial support helped prepare him for the high-pressure world of startup funding rounds.
Jiajun graduating from Imperial at the Royal Albert Hall
Jiajun graduating from Imperial at the Royal Albert Hall
How did he enjoy London? Jiajun’s parents moved him from China to the Netherlands when he was young, in search of a quiet life. By contrast, “in London, it seemed to me that everybody's running,” he says. His time at Imperial helped him realise that he wanted to become an entrepreneur.
[Imperial] is a place where, when if you have ambition, you can make it happen – you just need to work and push hard enough.
Jiajun works with relentless determination. A keen marathon-runner, this attribute translates to his life outside of work too. “Achieving a goal, whether in work or in running, takes planning, consistent effort, and the perseverance to keep going until you reach it,” he explains. “I’ve completed multiple marathons, and I especially love running through London - the blend of history, culture, and vibrant city life makes every run unforgettable.”
A new concept for energy storage
In 2014, before starting his PhD at Imperial, Jiajun began exploring alternatives to conventional battery technologies using water technologies with a few like-minded friends. They co-founded the company AQUABATTERY in the same year.
Nobody was talking about energy storage or all the problems around energy transition back then.
Achieving widespread decarbonisation would require cost-effective, scalable, and safe solutions for storing renewable electricity beyond the typical four to six-hour window provided by lithium-ion batteries. So, he developed a fundamentally new concept: an acid-base flow battery that stores energy using only water and table salt - simple ingredients which are abundant and available everywhere.
Unlike conventional flow batteries, Jiajun’s design turns saltwater into acid and base during charging. The acid and base streams are then stored in separate tanks over extended periods until energy is needed, at which point, mixing them back together generates electricity.
Sandro Macchietto, Professor of Process Systems Engineering at Imperial, who nominated Jiajun for the Alumni award, describes his invention as “an elegant, scalable solution that aligns with the broader goals of the circular economy and critical raw material independence.”
In his nomination, he highlights Jiajun’s “rare combination of intellectual brilliance, entrepreneurial vision, incredible work ethic, and deep sense of purpose.”
Turning saltwater into power
In the early days of AQUABATTERY, it was easy to secure small pockets of funding, Jiajun says, because the idea was so simple. “People love it, right? Things that you can find in your own kitchen can be used for massive energy storage for your home, for the neighbourhood, for grids, for solar and wind farms.”
AQUABATTERY water tanks
AQUABATTERY water tanks
It took several years before significant funding began to materialise. In 2017, this changed with the award of a Dutch national grant of around €0.6 million to build a demonstration pilot in Delft, the Netherlands, followed by a Horizon 2020 grant of €4 million to further develop the acid/base flow battery concept with a consortium of partners. Suddenly, AQUABATTERY found itself managing substantial funds, all while Jiajun hadn’t even finished his PhD.
Jiajun gave up the idea of pursuing a career in academia, along with his part-time role as Chief Technology Officer at Desolenator – another startup exploring the use of solar energy to purify complex water sources – to focus solely on AQUABATTERY.
In 2022, AQUABATTERY secured a further €2.5 million grant from the European Innovation Council’s Accelerator programme to advance its technology. Then in 2024, AQUABATTERY secured a seed investment of €6 million and a further large sum of funding with a consortium of partners in 2025. “This is helping us build the know-how, technology, and demonstrators needed for the commercialisation of long duration energy storage (LDES) systems,” says Jiajun. The total investment of this project is €30 million. Overall, Jiajun and his team have secured non-dilutive funding totalling more than €15 million.
Accolades have poured in too. Early in his career, Jiajun was featured in the Forbes 30 Under 30 Europe list in the “Manufacturing & Industry” category. More recently, in June 2025, he was awarded the prestigious EU Sustainable Energy Innovation Award by the European Commission, recognising his groundbreaking work, and, in November, he won an IChemE Global Award - widely regarded as the world’s most prestigious chemical engineering awards. Jiajun’s innovations and engineering work have gained truly international recognition, and in December 2025, he was elected a Fellow of the Netherlands Academy of Engineering - the highest professional distinction for engineers in the Netherlands.
At COP28 in Dubai, AQUABATTERY announced a collaboration agreement with Norwegian renewables company Statkraft. The partnership partially funded the latest real-world showcase of an AQUABATTERY system at Deltares, a leading Dutch research institute working towards a climate-resilient campus. There, AQUABATTERY could provide clean, safe, and flexible long-duration energy storage as a core enabler of Deltares’ plan to build a Paris Agreement-proof campus.
"It's about the team."
So how does life as a CEO compare to the world of academia? Jiajun says that the contrast is sharp. “In academia, when I was doing research, I sometimes had the feeling I could simulate, understand and conquer the world on my own - a one-man show.
The more I grow the company, the more I understand it’s not about me. It's about the team.
“But the more I grow the company, the more I understand it’s not about me. It's about the team. How can I help them succeed? What kind of resources do they need, how can I enable them to perform at their best? The challenge changes, and it is about supporting the people around you.”
It’s not been an easy transition for Jiajun. “I still want to do everything myself, but I also want others to do it even better, and to help them accelerate.” He adds, “there’s a lot of falling down, and getting back up again.”
Conserving energy and inspiring others
Jiajun actively advocates for innovation-friendly regulations that accommodate emerging technologies, visiting Brussels and the Hague to speak to and advise policymakers. He also regularly returns to Imperial to inspire and support young innovators. Being an entrepreneur, he says, “is not a conventional step. Many of my peers became academics or bankers. Only a few will try to build their own company, because it’s highly risky.” Nonetheless, he says, the unconventional step is worthwhile.
Speaking at Imperial’s Enterprise Day, he shared his journey from PhD student to cleantech entrepreneur and CEO. His story resonated strongly with students and researchers, particularly those from underrepresented backgrounds or seeking purpose-driven careers in science and engineering.
What advice does he have for young entrepreneurs and early career leaders in climate tech? Jiajun draws a parallel between running marathons and running a company. “It's about having that mindset of never giving up – have a crystal-clear target on what you want to execute, plan, focus, and keep going.”
Much like the batteries he’s making, “that means you need to conserve your energy, and use it strategically at the right moment,” he says. “It’s not simple. Running at a steady pace for a long time is the mindset that entrepreneurs need to have, while being flexible enough to adapt to changing environments."
Pausing, he adds, "I know that some people dream of a quick exit – to build an easy software solution and sell for millions or even billions. But I think if you truly want to make an impact, it's less about the quick wins. It's about building systems that can actually prevail in the long run.
So be bold, and take the first step. You’ll fall a few times, but you’ll get back up. Refocus and keep going – never give up!
Words by Sarah Webb | Photography by Victoria Ushkanova | Editing and design by Ellie Cawthera
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