How Shannon Xinjing Lee is Turning Eggplants Into Electrocatalysts

Dominic Phua
Dominic Phua / Dominic Phua

By Shannon Xinjing Lee, as told to Shiwani Srivastava

What powerful surprises are hiding in your pantry? That question drove Shannon Xinjing Lee, a 19-year-old student from Singapore, to develop a battery electrocatalyst—out of an eggplant! We asked Lee, who won the 2014 Young Scientist Award at the Intel International Science and Engineering Fair, what led her to this groundbreaking discovery.

I was the kind of child who constantly asked “why?” I didn’t do that well in science in primary school, but as I got older, it started making more sense. By the time I was in junior college [a pre-university program], I had opportunities to do research. That’s what made me fall for science.

The eggplant project started in a lab, with a mentor, trying to find a green, simple, and cheap cathode structure for metal-air batteries. [Metal-air batteries produce electricity by using oxygen in the air to spark a chemical reaction with a metal.] In other words, how might these batteries store and release more power without increasing costs or environmental impact? In the future, metal-air batteries will be able to power cars, but right now they rely on platinum, which is very expensive.

What makes metal-air batteries so light, yet able to deliver so much energy, is that they use air as the reactive material. Oxygen flows into the batteries, and that energy is harnessed as power. But you need a conductive surface—like carbon—for the reaction to occur. I figured, what carbon material is more environmentally friendly than fruits and vegetables?

I searched for something with a large surface area. I experimented with apples because they have high water content. Remove that water, and what’s left is a large surface area for oxygen to flow into. But apples weren’t good catalysts. Then I tried eggplants, which seemed to have catalytic properties. But when I tried to dig up related research to see if others had noticed this, there wasn’t much. My mentor encouraged me to keep at it. I was amazed by the results.

Carbonized eggplant is an excellent catalyst for metal-air batteries, largely because of its spongy, porous structure. Its thin cell walls make it easy to convert into sheets with lots of surface area for reactions to occur. In some ways, it even performed as well as platinum.

I didn’t expect to get one of the highest prizes at the Intel Science Fair, or all the media attention. It gave me the confidence to say, “Hey, I can really do this whole science thing!” Now I’m in medical school in Singapore. People kept telling me how stressful it would be, but I’m having a lot of fun. I’m no longer working on the eggplant electrocatalyst, but I did publish a paper on mass-producing low-cost carbon sheets from eggplant.

My hope is that the eggplant carbon sheets really do become a greener, cheaper, more efficient way of powering metal-air batteries. I want others to pick up where I left off and take it to the next level. That’s the beauty of science.