A company in China has developed a battery that can last longer than the devices it powers. The nuclear-powered BV100 is smaller than a coin and can provide power for 50 years without the need for recharging, according to Beijing-based start-up Betavolt Technology, the company behind the product. The prototype battery harnesses energy released by nuclear isotopes and uses semiconductors to convert that energy into electrical power, the company said. “The battery could enable devices like smartphones to operate indefinitely without recharging or drones to fly without landing,” the company said on its website. Aside from a lengthy lifespan, the battery is also said to perform well under extreme conditions. “Unlike traditional batteries, this nuclear battery operates safely under extreme conditions, from temperatures of 120 to minus 60 degrees Celsius, and is resistant to punctures and gunfire without catching fire or exploding,” Science and Technology Daily said in an article on January 8.
In addition to general civilian use, such a battery could be used in military applications like continuously flying drones, or for deep-sea monitoring devices that require long-term power supplies under extreme conditions, according to industry experts. The BV100 measures just 15 x 15 x 5 mm, with a power output of 100 microwatt and 3 volts. The company said it planned to mass-produce the battery by the end of this year and introduce a 1 watt version next year. The underlying principle of the nuclear batteries is isotope technology, first proposed in 1913 by British physicist Henry Moseley. It captures energy from the nuclear decay of radioactive elements. Unlike nuclear fission or fusion, nuclear decay is a spontaneous process in which isotopes emit radiation, leading to more stable new atoms. Scientists encapsulate these isotopes, converting the energy emitted into usable electrical power.
The lifespan of a nuclear battery correlates with the half-life of the isotope used as its energy source. For instance, the half-life of nitrogen-16 is only 7.13 seconds, whereas that of potassium-40 is around 1.3 billion years. The BV100 uses nickel-63 as its radiation source, which has a half-life exceeding 100 years, ensuring it stays operational throughout its 50-year lifespan. Different isotopes emit alpha or beta particles and gamma rays during decay. Different isotopic raw materials can yield a variety of routes to make nuclear batteries. For instance, the nuclear battery on China’s Chang’e-3 lunar rover, launched in 2013, used a thermo-electric converter to harness the heat produced by alpha particles released by the decay of plutonium-238 to generate electricity. Nasa’s Curiosity Mars rover uses a similar technology.
The BV100 battery is classified as betavoltaic, and using semiconductor junctions, it generates an electric current directly from beta particles emitted from a radioactive source. The beta particles released during the decay of nickel-63 are irradiated on the diamond semiconductor to form an electric field and achieve electrical energy output when connected to the circuit. To improve energy conversion efficiency, Betavolt’s researchers developed a unique single-crystal diamond semiconductor, using a boron-doped diamond as a substrate and a plasma chemical vapor deposition method to create the diamond semiconductor converter. The company claimed to be the only firm in the world capable of doping and manufacturing large-scale diamond semiconductor materials, a key component in making nuclear batteries.
The BV100 uses a modular structure, sandwiching a 2-micrometer thick nickel-63 layer between two 10-mm thick diamond semiconductors, forming a power-generating unit. By connecting multiple such modules, researchers can configure power outputs ranging from a few microwatt to several watt. “The battery’s energy conversion efficiency currently stands at 8.8%, with potential improvements using higher purity nickel-63 radiation sources,” the company said on its website.
Zhang Shixu, Associate Professor from the School of Nuclear Science and Technology at Lanzhou University in Gansu province however cautioned that designing nuclear batteries for small electronic devices like smartphones and drones is challenging. “Concerns include nuclear safety and control, radiation protection limiting battery performance, and radiation damage to semiconductors from the gamma rays accompanying beta radiation in betavoltaic batteries,” he said, adding that nickel-63, used in the BV100, emits stronger radiation than tritium isotopes used by CityLabs, a company in the United States that has been developing betavoltaic batteries in the nanowatt to microwatt range since 2010. Nickel-63 decays into non-radioactive copper-63, posing no pollution threat, a Betavolt researcher said, as reported by the South China Morning Post.
