The Sankei Shimbun 
A prototype rechargeable battery made from depleted uranium, which is dissolved in the greenish liquid on the left. (Courtesy of the Japan Atomic Energy Agency)
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Japan's Atomic Energy Agency (JAEA) has developed the world's first rechargeable battery using the depleted uranium left over from producing fuel for nuclear reactors.
A prototype 10 centimeters wide achieved a voltage of 1.3 volts, close to the 1.5 volts of an everyday alkaline battery, and successfully lit an LED, the agency said in March 2025.
If developed into a practical application, the technology could help solve two environmental problems - providing a use for the roughly 16,000 tons of depleted uranium stored domestically and as a large-scale storage solution for renewable energy sources. Unlike other countries, Japan does not use depleted uranium for military munitions or civilian applications.
A Stable Prototype
Tests showed the prototype to be stable, with no degradation after repeated charges and discharges. It can potentially be used to create batteries in larger sizes than lithium-ion batteries and is more efficient than batteries using vanadium electrodes, an existing solution for large-scale energy storage.
Like all electric batteries, the new technology uses negative and positive terminals with an electrolyte to facilitate the movement of charged ions between them. The newly developed battery employs uranium on the negative side and iron on the positive side, taking advantage of the potential difference between them.
Potential for Renewable Energy Grids
Renewable energy sources such as wind and solar power are affected by weather conditions, creating a demand for large-scale storage batteries to provide a stable supply. The breakthrough has created a battery type that is likely to be suitable for such applications.
"We hope to contribute to solving the depleted uranium problem and promoting the country's energy policy," the JAEA said.
Depleted uranium is mostly composed of isotopes that are stable against fission and have low radiation.
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Author: The Sankei Shimbun
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