Researchers at McGill University have created a new kind of battery that is flexible, biodegradable, and far greener than traditional designs — and it could help tackle the growing mountain of electronic waste.
Made using natural acids and gelatin, this innovative battery is designed for next-generation wearable and implantable devices.
Associate Professor Sharmistha Bhadra from McGill’s Trottier Institute for Sustainability in Engineering and Design says the idea came from a simple question: could a battery be made to stretch and eventually break down naturally without harming the environment?
“We use a lot of batteries in our lab for wearable devices, and they eventually stop working and get thrown out,” she explained.
“We wanted to see if it was possible to make something biodegradable and flexible that could still perform properly.”
Traditional batteries rely on heavy metals, which can be toxic and harmful to ecosystems when discarded.
To avoid this, the team turned to magnesium and molybdenum, two metals already known for being more environmentally friendly.
However, past research showed that magnesium-based batteries often suffer from poor performance because the metal can form a layer that blocks the chemical reactions needed to generate power.
To solve this problem, doctoral student Junzhi Liu tested two common natural acids: citric acid, found in fruits like lemons, and lactic acid, found in milk and the human body.
When these acids were added to the battery, they helped break down the blocking layer on the magnesium, allowing the battery to deliver stronger and more consistent power for a longer time.
The idea of using citric acid was even inspired by a childhood science experiment. “Many people try making a lemon battery as kids,” Bhadra said.
“The lemon has enough ions to conduct electricity. That’s what gave us the idea to explore citric acid further.”
To give the battery its stretchable quality, the researchers mixed the acids into gelatin, a natural, biodegradable material. They also used a “kirigami” design, which involves cutting patterns into the battery so it can stretch and bend without breaking.
Thanks to this design, the battery can stretch by up to 80 percent and still keep working.
In testing, the battery produced 1.3 volts of power — slightly less than a standard AA battery — but still strong enough to run small devices. The team even used it to power a touch-sensitive sensor worn on a finger, demonstrating its potential for real-world applications.
The researchers believe this technology could be especially useful in medical implants, fitness trackers, and flexible Internet-of-Things devices. They are now looking for industry partners to help improve the battery’s performance and reduce its size further.
Electronic waste is one of the fastest-growing waste streams in the world, often ending up in landfills or being shipped to low-income countries for disposal. By designing batteries and electronics that naturally break down, the team hopes to address part of this global problem.
“If you visit a landfill, you’ll see old electronics sitting there for years,” Bhadra said. “We’re not very good at recycling them. By creating biodegradable electronics, we may be able to reduce some of that long-lasting damage to the planet.”
Source: McGill University.
