McGill Researchers Create Eco-Friendly Stretchable Battery

Researchers at McGill University have developed a groundbreaking stretchable and biodegradable battery designed for use in wearable and implantable devices. This innovative battery, utilizing citric or lactic acid along with gelatin, eliminates the need for toxic materials and aims to significantly reduce electronic waste.

The project, led by the Trottier Institute for Sustainability in Engineering and Design, addresses a pressing environmental concern. According to Sharmistha Bhadra, an Associate Professor of Electrical and Computer Engineering, the lab frequently discards batteries used in wearable technology. “This project asked whether we could make something biodegradable and stretchable that still performs well,” she stated.

Innovative Ingredients Enhance Performance

Traditional batteries often rely on heavy metals for their electrodes, posing environmental hazards. In a significant shift, the McGill team replaced these harmful components with magnesium and molybdenum, materials recognized for their biodegradability. Previous studies indicated that magnesium-based batteries typically underperformed compared to conventional options. To tackle this issue, researchers experimented with two natural acids—lactic acid and citric acid—combined with gelatin, ultimately discovering that these additives improved battery performance.

Junzhi Liu, a doctoral student leading the development and testing of the battery, explained the chemical interactions involved. “Magnesium can generate a layer that stops the reaction between electrolyte and electrode,” he noted. “We found we could break down this layer with citric or lactic acid and increase the battery’s lifetime and its voltage.”

Bhadra drew inspiration for the use of citric acid from a familiar childhood science project. “Many people make a lemon battery as kids, where you connect a copper wire to a light. The lemon has enough ions to conduct electricity,” she explained.

Designing for Flexibility

To achieve the required stretchability, the researchers suspended both acids in gelatin and applied a kirigami pattern to the battery structure. This technique allows the material to bend and stretch without breaking. While kirigami designs have previously been utilized in stretchable electronics, their application in biodegradable batteries is a novel approach.

The researchers found their battery could be stretched up to 80 percent without compromising performance. In practical tests, the battery was integrated into a pressure sensor to simulate real-world applications. It generated slightly less power than an AA battery, producing 1.3 volts compared to the standard 1.5 volts. “We wanted to see if we could run an actual wearable or sensor,” Bhadra remarked, highlighting the battery’s potential for various applications.

The team also developed a touch-sensitive device powered by the battery, designed to be worn on a finger. This design shows promise not only for medical implants and wearables but also for flexible Internet-of-Things devices.

Addressing Electronic Waste

The researchers are currently seeking industry partners to further advance the project. Future steps include enhancing battery performance, miniaturizing it for implantable applications, and integrating the design with biodegradable circuits. Bhadra emphasized the importance of this work, stating, “The whole motivation is to address the growing problem of electronic waste. If you go to a landfill, you see discarded electronics piled up for years.”

The issue of electronic waste is critical, as much of it ends up in lower-income countries where recycling efforts are inadequate. The McGill team believes their biodegradable electronics could contribute to solving part of this global challenge.

This research, titled “Gelatin-Organic Acid-Based Biodegradable Batteries for Stretchable Electronics,” was published in Advanced Energy and Sustainability Research in August 2025 and was funded by the McGill Sustainability Systems Initiative. The findings represent a significant step forward in the development of environmentally friendly battery technology, potentially paving the way for a more sustainable future in electronics.