Researchers have developed an eel-inspired hydrogel battery that achieves unusually high power output without toxic materials and with a flexible, biologically compatible design. In many aspects, this is a significant advance in soft energy storage technology. The breakthrough was reported via research statements from Penn State University.
“The electrocytes in electric eels are ultra-thin biological cells, capable of generating over 600 volts of electricity in a brief burst. These cells achieve very high-power densities, meaning they can produce a lot of power from small volumes,” said Joseph Najem, assistant professor of mechanical engineering and corresponding author.
This new type of battery draws direct inspiration from the electric organs of eels, which use stacked ionic cells to generate powerful electrical discharges. Scientists have applied the same ionic gradient principles to create a hydrogel-based power source capable of delivering higher power densities than earlier gel batteries, while remaining flexible, environmentally stable, and free of heavy metals typically used in conventional batteries.
Dor Tillinger, doctoral candidate and co-first author, said, “We found that using thin hydrogel naturally reduced the internal resistance of the material, which increased the power densities we could output.”
The research team at Penn State University engineered ultra-thin layers of hydrogel: each just 20 micrometers thick, far thinner than a human hair. They used spin-coating fabrication and carefully tuned chemical mixtures. These thin layers reduce internal resistance and allow for more efficient ionic conduction, enabling the system to achieve power densities around 44 kW/m³, surpassing many existing hydrogel-based designs.
Crucially, the battery design does not require mechanical support structures, a common limitation in earlier biomimetic energy designs. Instead, the hydrogel solution itself forms a self-supporting architecture that remains flexible and stable across a wide temperature range. Lead researchers pointed out that the incorporation of chemicals such as glycerol helps the hydrogel retain water and conductivity even at temperatures as low as –112°F (–80°C).
The team explained that their approach takes advantage of the same physics seen in eel electrocytes, i.e., specialized cells that can produce bursts of several hundred volts to stack ionic gradients and mimic biological electrical generation.
Earlier studies have similarly explored ionic gradients and hydrogel compartments to emulate the electric eel’s power generation, demonstrating potential for flexible, biocompatible power sources.
Because the hydrogel materials are non-toxic, highly flexible, and biologically compatible, the technology shows promise for a range of applications that traditional rigid batteries cannot serve. These include wearable electronics, medical implants and sensors, soft robotics, and other systems requiring power sources that conform to biological interfaces.
Penn State research team also included Derek Hall and Haley Tholen, while the research was supported by the Air Force Office of Scientific Research. You can check all their findings in Advanced Science journal.