Ion man: Meet Ankur Gupta, the math whiz redefining how energy is stored

Ankur Gupta, who studied at IIT-Delhi and the Massachusetts Institute of Technology (MIT) and pursued postdoctoral research at Princeton University, and is now an assistant professor of chemical and biological engineering at the University of Colorado, Boulder, has led just such an effort.

He has spent seven years unravelling exactly how high-performing energy-storage devices work, all the way down to the nanopores (we’ll get to what those are in a bit), working alongside Pawel Jan Zuk of the Polish Academy of Science and Colorado Boulder PhD student Filipe Henrique.

This team’s research has now opened the door to a re-imagined energy-storage system that could potentially recharge a car in minutes, a laptop in under a minute, and a phone in seconds, according to findings that have made news worldwide since they were published in Proceedings of the National Academy of Sciences in May.

The ramifications are dramatic, for the role of energy in our lives. The proposed system could change how power grids deal with fluctuating inflows. It could alter how we use electric vehicles, digital devices, even lifts and uninterrupted power supply (UPS) systems.

The big shift would involve making supercapacitors a core element of electronic devices. But they would be supercapacitors of a very different kind.

So far, these energy-storage systems — which soak up energy really fast, but also discharge it quickly — have been used in situations where relatively short-lived streams of energy are required, such as UPS and wireless alarms, laptops and cellphones. Since they don’t last long on a single charge, they remain unsuited for use in something like an electric car. And they remain relatively high-maintenance wherever they are used.

For decades, researchers have tinkered with new materials, in attempts to get supercapacitors to hold on to their energy for longer. But in none of this research, says Gupta, was anyone theoretically studying what was happening at the molecular level within.

Say a supercapacitor uses a dense network of carbon to soak up energy in the form of charged ions, retaining its charge as long as these ions can zip back and forth between electrodes. Why was no one asking the question, Gupta wondered, of how these ions move within such a network; and how these movements might be made faster, for better results?

When Gupta dove in, studying the movement of ions within a single cylindrical nanopore of carbon, it was a bit like examining the flow of dense traffic down a narrow road, he says. Using mathematical models, the recent paper shows that it is possible to predict ion movement across a complex network of pores.

This finding is expected to upend research in the area because, so far, the focus has been to design materials that can soak up the most energy, and then find ways to keep that energy contained. Now, the effort could focus instead on materials that, quite simply, boost the movement of charged ions.

The search has gone all the way back to the edges of the board. Entirely new horizons are visible. It is possible, Gupta says, that biodegradable materials (think, wood) could be roped in.

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Gupta, 34, says his journey towards supercapacitors began with a love of complex math, in school.

Growing up in Ghaziabad, he was a high-performing student and had the usual dreams of pursuing engineering at an Indian Institute of Technology (IIT). But he didn’t only want a well-paid job. He wanted to invent and discover. That was always what excited him about science.

“The idea that so many things around us can be explained through mathematical models was fascinating to me,” he says. “In school, I loved spending time with mathematical problems that took time and effort. Just the idea of answering a question, or even rediscovering something that somebody had already done, but doing it differently, was very, very satisfying.”

After graduating in chemical engineering from IIT-Delhi, Gupta headed to the US, where he developed an interest in supercapacitors as a postdoctoral fellow at Princeton University, in 2017. It is here that he met Zuk, and the two began working together in 2019.

Together, they began to create and test models as they sought to understand the “traffic movements” within supercapacitors. They found first success in a paper published in the journal Physical Review Letters in 2020. It laid out, in rare detail, how ions move through a single cylindrical nanopore. “The paper was widely praised and we felt that we should keep working in this direction,” Gupta says.

In 2022, his PhD student Henrique joined the team. The trio expanded the scope of study from a single pore to an intersection of pores (or a junction). “The key question we addressed is how the ions will split along junctions, and how that will unfold when we have thousands and perhaps millions of interconnected junctions,” Gupta says.

What excites him now is that he could be shaping the future. In a world that is becoming more electric, and is likely to rely more heavily on renewable sources of electricity such as solar and wind power, which are prone to fluctuation, smarter energy storage will be vital, Gupta says.

“Since supercapacitors can pack energy in and can be programmed to release it very fast too, they would be better placed to deal with fluctuations, as we draw more of our energy from the wind and the sun.”

And, of course, they could make it possible to charge a car in minutes, and a phone in just a few seconds.