Water-Based Supercapacitor Endures 60,000 Charge Cycles Without Loss

Researchers at Hamburg University of Technology have developed a supercapacitor that uses pure water confined within nanometer-scale clay channels to store and transfer electrical charge efficiently.

This innovative device, named the “Blue Capacitor,” employs pure water as its electrolyte, differing from traditional systems that require chemical additives to conduct electricity.

Dr. Vasily Artemov from the Cluster of Excellence “BlueMat—Water-Driven Materials” at Hamburg University of Technology explained that their objective is to create energy storage technologies that are safer and more sustainable by utilizing abundant natural materials instead of complex chemical compounds.

He added that the device operates efficiently, maintains a relatively high voltage for a water-based system, and demonstrates stability over tens of thousands of charging cycles.

Nanometer-Scale Confinement of Water

Typically, pure water is considered unsuitable for energy storage because it lacks the conductive properties needed without added salts, acids, or organic solvents. Conventional batteries and supercapacitors rely on such chemical mixtures to function.

The research team’s approach involves confining pure water within microscopic channels formed by a combination of clay minerals and graphene, an ultra-thin and highly conductive form of carbon.

This combination creates a dense network of millions of parallel channels, each approximately one nanometer wide—about 100,000 times thinner than a human hair—altering the fundamental behavior of the water inside.

Artemov noted that their findings demonstrate nanoconfined water can act as the active electrolyte in a practical energy-storage device.

To observe this phenomenon, the team utilized PETRA III at DESY, a powerful particle accelerator research facility, which allowed visualization of ultra-thin water films within the clay structures.

Professor Patrick Huber, co-author of the study, stated that only with DESY’s advanced X-ray source could they visualize these individual water layers.

Extensive Performance Evaluation

The Blue Capacitor functions as a supercapacitor, storing energy by separating electrical charges rather than relying on chemical reactions. This mechanism enables rapid charging and discharging, alongside long operational lifetimes.

During laboratory tests, the device endured over 60,000 charge-discharge cycles without degradation and operated at voltages up to 1.6 volts.

This voltage is notably high for a water-based system, which typically decomposes into hydrogen and oxygen gases at lower voltages.

Although commercial deployment remains several years away, the development of a non-toxic, non-flammable capacitor presents significant potential.

Such technology could facilitate energy storage for renewable sources like solar and wind, contribute to electrical grid stabilization, and power devices requiring frequent, rapid charging.

Artemov emphasized that uncovering the unexpected nanoscale properties of water paves the way for new technological innovations.

Beyond energy storage, this discovery may lead to advancements in water-based nanoscale sensors and bio-inspired computing technologies.

The research findings have been published in the journal Nature Communications.