The Japan Atomic Energy Agency (JAEA) says it has developed the first “uranium rechargeable battery” that uses the chemical properties of uranium for practical use, and has verified its performance in charging and discharging.
The uranium-based rechargeable battery has the potential to be a power control for renewable energy generations such as mega-solar power plants, JAEA noted. “These results are expected to provide a new resource value to depleted uranium, which is generated in nuclear fuel production and unutilised in the immediate future”.
Depleted uranium (DU) is generated as a byproduct of enrichment and other processes. Since DU cannot be used as fuel in light water reactors, approximately 16,000 tonnes of DU are stored in Japan. To utilise DU as a new resource, the concept of rechargeable batteries using uranium as an active material was proposed in the early 2000s.
Since then, the need for rechargeable batteries has been increasing with the rapid introduction of renewable energy sources. Power generation from solar, wind, and other sources is affected by weather conditions and is therefore subject to fluctuations. To stabilise the power supply in this situation, energy storage devices such as rechargeable batteries are necessary.
The JAEA research team has now developed a rechargeable battery using uranium as the active material and clarified its charging-discharging performance for the first time. The battery uses uranium as the negative electrode active material and iron as the positive one. The single-cell voltage of the prototype uranium rechargeable battery was 1.3 volts, which is close to that of a standard alkaline battery (1.5 volts). The battery was charged and discharged 10 times, and the performance of the battery was almost unchanged, indicating relatively stable cycling characteristics.
Having verified the charge and discharge performance of the battery, JAEA is now “developing flow cells, including electrodes for higher capacity (redox flow battery) and the system for circulating electrolytes (solution dissolving active materials), to promote these results for practical use”. JAEA will now investigate whether it is possible to increase capacity by increasing the amount of circulating electrolyte and the concentration of uranium and iron, and what the optimal materials are for the electrodes and membranes that make up the storage battery.
JAEA noted that, if uranium rechargeable batteries are increased in capacity and put to practical use, the large amount of DU stored in Japan will become a new resource for output controls in the electricity supply grid derived from renewable energy.
This research was conducted by Assistant Principal Researcher Dr Kazuki Ouchi, Researcher Dr Katsuhiro Ueno, and Senior Principal Researcher Dr Masayuki Watanabe of the Special Team for Battery Energy Storage, at the NXR Development Centre, Nuclear Science Research Institute JAEA.
