It turns out that pure water can store electricity.

A new study by the Hamburg University of Technology in Germany reveals that trapping water inside nanometer-sized clay channels creates a supercapacitor capable of efficiently storing and moving electrical charge.

In this work, pure water has been used as an electrolyte to carry electrical charge. This system is dubbed the “Blue Capacitor.”

“Our goal is to develop safer and more sustainable energy-storage technologies based on abundant materials rather than complex chemical compounds,” said Dr. Vasily Artemov from the Cluster of Excellence “BlueMat—Water-Driven Materials” at Hamburg University of Technology. 

“The device stores and releases energy efficiently, operates at a comparatively high voltage for a water-based system, and remains stable over tens of thousands of charging cycles,” the lead author added.

Nanometer-sized channels

Pure water is mostly considered a terrible medium for storing power. To conduct electricity, batteries and supercapacitors have always required a chemical cocktail of added salts, acids, or volatile organic solvents. Without them, energy storage simply stalls.

But the research team tried to change this through its functional “Blue Capacitor” technology. It is an energy-storage device made entirely from three of Earth’s most abundant, naturally occurring materials: water, clay, and carbon.

The system has been engineered to confine pure water within microscopic channels, thereby altering the liquid’s fundamental behavior.

The clay minerals were blended with graphene — a highly conductive, ultra-thin form of carbon. When combined, these materials form a dense labyrinth of millions of parallel channels. Each channel measures just one nanometer wide, roughly 100,000 times thinner than a human hair.

“Our results show that nanoconfined water can serve as the active electrolyte in a practical energy-storage device,” noted Artemov.

To actually see this happening, the team had to look more closely than almost anyone has before. They utilized PETRA III at DESY, one of the world’s most powerful particle accelerator research centers. 

“Only with DESY’s brilliant X-ray source PETRA III, were we able to visualize the ultra-thin sheets of individual water films within the clay structures,” said Prof. Patrick Huber, co-author of the paper.

Rigorous testing

The new device is a supercapacitor, a type of energy-storage technology that stores energy by separating electrical charges rather than through chemical reactions. Because of this mechanism, supercapacitors feature rapid charging and discharging capabilities, along with exceptionally long operational lifetimes.

In testing, the proof of concept showed promising results. 

In rigorous laboratory testing, the Blue Capacitor survived more than 60,000 charge-discharge cycles without degrading. Furthermore, it operated at up to 1.6 volts. 

That is an exceptionally high voltage threshold for any water-based system, which typically breaks down into hydrogen and oxygen gases at much lower voltages.

While commercial applications are still years away, the implications of a non-toxic, un-burnable capacitor are massive.

It offers a promising path for future energy storage. Potential applications include managing renewable energy from solar and wind power, stabilizing electrical grids, and powering devices that need rapid, frequent charging cycles.

According to researcher Artemov, understanding the unexpected nanoscale properties of a familiar substance opens the door to the development of entirely new technological applications. 

Beyond green power, the discovery opens the door for water-based nanoscale sensors and bio-inspired computing.

The findings were published in the journal Nature Communications.

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The life cycle of an electric vehicle battery has been a violent, one-way street. When a battery dies, the industry routinely tears it apart to access the parts that matter. High-tech recyclers either blast the dead cells in extreme-heat furnaces or grind them into a powdery substance known as “black mass” before drenching them in harsh, corrosive acids.

It is an expensive, carbon-intensive, and messy way to extract scarce minerals like nickel and cobalt. But what if you didn’t have to destroy a dead battery just to rebuild it?

Researchers at Cornell University have developed a way to overcome the destruction altogether. Rather than smashing the battery, the method turns to chemical washing. 

In this, intact components were immersed in a specialized electrochemical bath to restore 95 percent of the dead batteries. Plus, this method could cut recycling manufacturing costs by 56 percent.

“We repair them, as is, without shredding or powdering them, and then put them back into a new battery,” said Vibha Kalra, the Fred H. Rhodes Professor of Chemical Engineering in the Cornell Duffield College of Engineering. 

“The dissolution is basically what helps the battery recover its capacity. It shows 95 percent recovery. So we are shortening the circularity loop immensely,” added Kalra. 

Cost-saving battery fix

To understand how it works, look at what actually happens when a battery dies.

Batteries don’t usually run out of minerals. But, as electricity flows back and forth between the positive and negative sides, a thick, crusty layer of gunk gradually builds up inside the cell.

Engineers call this the solid electrolyte interphase. The materials are all still there, but the energy can no longer flow. Standard recycling destroys the whole part just to clean it. 

Cornell’s method, called Direct Electrode-to-Electrode Regeneration (DEER), is far gentler. 

Workers open the casing and pull out the battery’s core parts — the electrodes — while these are still completely intact. Then the parts are submerged into a chemical solution called 1,3-dimethyl-2-imidazolidinone. The liquid targets the gunk. It dissolves the insulating buildup, leaving the delicate internal structures perfectly preserved. 

The process cuts down air pollution and slashes industrial water consumption.

The growing demand

At this moment, the world is grappling with disruptions to global supply chains for essential battery ingredients. The United States currently possesses very few domestic reserves of the critical minerals required to build modern batteries.

US depends mostly on complex, foreign supply chains to import materials. It also lacks the massive infrastructure needed to refine raw materials or rebuild crushed battery powder from scratch; domestic recycling has lagged.

“When these lithium-ion batteries came about, nobody was thinking about how these minerals are limited on the Earth’s crust, and you cannot make them forever,” Kalra said. “In recent years, people are realizing you can’t just keep making batteries, because you don’t have enough material.”

By keeping the battery components intact, the DEER method eliminates the need for expensive, overseas refabrication. It allows the entire recycling process to happen locally, cheaply, and quickly. 

The research team’s next step is to test the DEER method on larger, industrial-scale batteries and adapt the process to combat other forms of wear, such as permanent lithium loss. 

Currently, the technique successfully treats batteries at a 70-80 percent state of health — the typical retirement threshold for electric vehicles. But researchers believe they can widen this recovery window by targeting these additional degradation mechanisms.

The study findings were published in the journal Energy and Environmental Science on June 9. 

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