"50 years of stable self-power generation" nuclear battery to change the life of lithium battery?
The large-scale commercial and civilian progress of nuclear batteries has once again attracted widespread attention. When will nuclear batteries that have not been charged for tens or even hundreds of years be applied to mobile phones, electrical appliances, and cars?
Recently, some domestic companies have claimed to have successfully developed civil atomic energy batteries, which can be stably self-generated for 50 years and will soon be put into mass production, "far ahead" of European and American scientific research institutions and enterprises. The company said it plans to launch a 1-watt battery in 2025, and if the policy allows, the atomic battery can make a mobile phone never charge, and now drones that can only fly for 15 minutes can fly forever.
As soon as this news came out, some people were excited, shouting "lithium batteries are going to be revolutionized!", and some netizens questioned the company's so-called product prospects. In fact, nuclear batteries have been around for a long time, and have been of interest to researchers since the last century. Since the 50s of the 20th century, nuclear batteries have entered a period of rapid development. There are great hopes for this long-lived energy source, but until now, the main application scenarios of nuclear batteries are still limited to aerospace, polar, deep-sea, pacemakers and other fields. From the perspective of conversion efficiency, output power, cost and radiation safety management, it is still too early for nuclear battery civil use to speak. Compared with the lithium batteries that can be found everywhere, nuclear batteries are difficult to enter people's daily life.
Nuclear batteries, starting from space
Nuclear power plants work on the principle of nuclear fission, and the "artificial sun" known as the ultimate energy source is the nuclear fusion reaction. While fission and fusion are both exogenously triggered nuclear transitions, nuclear batteries utilize a different kind of decay: it is a spontaneous nuclear transition, also known as radioactive decay. Therefore, a nuclear battery, or radioisotope battery, is a device that converts the energy released when a radioisotope decays into electrical energy.
Because the decay process is continuous and not affected by the environment, nuclear batteries are known for their strong anti-interference, stable and reliable, high energy density, and can work for years, decades or even hundreds of years depending on the half-life of the radioactive source. This gives it an advantage in extreme conditions and where a stable power supply is required over a long period of time. According to the different energy conversion methods, nuclear batteries can be divided into thermal conversion nuclear batteries (converting the thermal energy generated during isotope decay into electrical energy) and non-thermal conversion nuclear batteries (converting charged particles or decay energy generated by radioactive isotopes directly or indirectly into electrical energy).
Substantial progress in nuclear battery research began in the 50s of the 20th century, thanks to the rapid development of aerospace technology, which has generated a great demand for high-efficiency and long-life batteries.
In the field of aerospace, there are many "well-known cases" of heat-converted nuclear batteries. In 1977, the United States launched the "Voyager 1" spacecraft carrying a plutonium-238 nuclear battery, which has been in space for 46 years, creating a glorious record in the history of the world's satellite voyages, and the nuclear battery will ensure that the scientific instruments it carries will continue to work until 2025. The nuclear power unit carried by the Mars rover "Curiosity" is a nuclear battery weighing about 45 kilograms and generating 140 watts of electricity, containing about 5 kilograms of plutonium-238. In 2013, the mainland's "Chang'e-3" carried an isotope heat source into the sky, and the plutonium metal block 238 in the nuclear battery was equivalent to a "warm baby". With it, there is no need to worry about low-temperature frostbite equipment from minus 150 degrees to 180 degrees Celsius on moonlit nights.
The above-mentioned radioisotope thermoelectric generator nuclear battery technology is the most mature and the earliest application, but the cost is extremely expensive. Take the nuclear battery system of the Perseverance rover, for example, the price is as high as $75 million.
Research progress on nuclear batteries. This figure is based on the article "Nuclear Battery Overview and Prospects", published in Nuclear Physics Review in December 2020
In recent years, the industrialization of another technical branch, radiated volt effect nuclear batteries, has frequently "gone out of the circle". With the improvement of semiconductor material manufacturing technology, the practical application of such batteries has become possible.
In 2012, a civilian nuclear battery called NanoTritium, which has been uninterrupted and not charged for 20 years, appeared on the domestic e-commerce platform for sale, priced at 6980 yuan, which immediately aroused heated discussions on the Internet. This is not a copycat, but a tritium battery launched by City Labs in the United States. In 2010, the company received a general license for the NanoTritium radiant volt effect nuclear battery.
City Labs chose tritium that emits only low-energy β particles that can be shielded with a very thin material, making it a safer and easier to seal radioactive source. According to the company's official website, its tritium battery has passed third-party testing by global aerospace and defense giant Lockheed Martin, which confirms the product's tolerance to extreme temperature changes (-55°C to +150°C). Tritium has a half-life of around 12 years, and City Labs says that "early NanoTritium batteries developed 15 years ago are still operating efficiently, and simulations show that they will continue to operate for more than 20 years." ”
NanoTritium电池
Nuclear batteries for civilian use, where has it gone
The main factor that hinders the civilian use of nuclear batteries is not safety.
As an energy source for nuclear batteries, isotope radioactive sources must meet the conditions of long half-life, high power density, low radioactive danger, easy processing, economy and easy shielding. Radiant volt effect nuclear batteries generally use pure β radiation radiation sources, which have a very shallow penetration depth of the substance, and can be blocked by a few pieces of paper, without external radiation damage.
The high price is one of the main limiting factors for the large-scale civilian use of nuclear batteries.
More than 10 years after bringing tritium batteries to the commercial market, what is the business of City Labs, the originator of the field? "Betavoltaic batteries and nuclear batteries are not yet widely available to individual consumers, and most of these power sources are still under development and refinement. Some companies, such as City Labs, offer betavolt batteries for commercial and scientific use. According to City Labs, the average consumer will not buy their products, and the company usually deals with long-term partners or scientific organizations interested in the technology.
The Paper learned from the company's website that the base price of each tritium battery is $5,250. Of course, discounts are available for bulk orders, and there is an additional charge for customized products.
Conversion efficiency and output performance are the shortcomings that nuclear batteries have to face in expanding their applications.
In December 2023, the Institute of Nuclear Energy Safety of the Hefei Institute of Physical Sciences of the Chinese Academy of Sciences announced that the Han Yuncheng project team of the institute has made new progress in the research field of beta radiation volt nuclear batteries, and the relevant research results were published in the journal Nuclear Science and Techniques. According to the paper, beta-radiated volt-volt nuclear batteries use beta particles released by radioisotopes to convert into electrical energy, which has the characteristics of long life, high energy density, tiny size and excellent anti-interference ability, and is widely regarded as one of the most promising energy alternatives in microelectromechanical systems (MEMS). However, the traditional planar battery is limited by the semiconductor structure and the loading of the radioactive source, and the semiconductor converter can only use the decay energy released by the radioactive source on one side, resulting in low output power and conversion efficiency, and the output power is limited to the nW level, which cannot meet the power requirements of the MEMS system.
The power of radiated volt nuclear batteries is on the order of nanowatts to milliwatts. According to City Labs, the company's nuclear battery products are in the nanowatt, microwatt, and milliwatt ranges.
Zhu Li, executive deputy director of the Office of Radiation Protection at Tsinghua University, previously explained the tritium battery launched by City Labs, "Its power is only 0.84 milliwatts at most, which shows that NanoTritium cannot be applied to mobile phones and other fields." ”
In addition, the Regulations on the Safety and Protection of Radioisotopes and Radiation Devices and the Administrative Measures for the Safety Licensing of Radioisotopes and Radiation Devices clearly stipulate that the exemption of radioactive sources must be accompanied by filing documents, that is, the relevant commercial activities must be approved.
Let's go back to the companies mentioned at the beginning of the article that claim to have successfully developed civilian nuclear batteries, is it really possible to "launch a 1-watt battery in 2025"?
Combining nickel-63 nuclear isotope decay technology with China's first diamond semiconductor module, the company will launch its first product, the BV100, which is the world's first nuclear battery to be mass-produced, with a power of 100 microwatts, a voltage of 3V, and a volume of 15 x 15 x 5 cubic millimeters, which is smaller than a coin. Nuclear batteries are generating 8.64 joules per day and 3,153 joules per year. Multiple of these batteries can be used in series and parallel.
Schematic diagram of the structure of the atomic energy battery product displayed by the company
Nickel-63 has a half-life of 100 years, and in terms of half-life, nickel-63-based nuclear batteries can indeed operate for at least 50 years.
However, a scholar engaged in applied research on nuclear technology expressed doubts to The Paper about the company's product introduction and goals. "At present, the power has not reached this level, and nuclear battery applications still need to rely on new materials and new processes to increase the output power. ”
There is also no shortage of doubts on social platforms about the company's concept of "nuclear battery mobile phones". "1 watt = 1,000,000 microwatts, which means that to build a 1 watt nuclear battery, you have to be 10,000 times larger than a coin. To make something 10,000 times the size of a coin as big as a mobile phone battery in two years, Moore's Law can't carry it, let alone materials science. The netizen also asked rhetorically, the peak power of the current mobile phone can reach 13-15 watts, what can 1 watt do?
Some netizens also pointed out that this product is not only not suitable for mobile phone batteries, even if it is used as an external power supply, it has no advantage over other fast charging of 100 watts, not to mention the price of nickel-63.
Tianyancha data shows that Beijing Betavolt New Energy Technology Co., Ltd. was established in April 2021, the legal representative is Musov Zaul, and the number of insured people is 0. Beijing Minming Innovation Technology Co., Ltd. holds 94% of the shares, and the five shareholders of Minming Innovation are Musov Zaur, Musaf Mohammed, Kugotov Ancol, Ning Xiaohan and Wang Zhenyuan, and the number of insured people is also 0.
The patent information of Beijing Betavolt New Energy Technology Co., Ltd. is shown in the figure below:
"In the civilian sphere, the unregulated use of nuclear batteries is dangerous. Qiao Dayong, a professor at the Aerospace Micro-Nano Laboratory of Northwestern Polytechnical University, said in an interview with China Science News, "There are international regulations on the civilian use of nuclear batteries, and the half-life of some radioactive sources is even thousands of years. ”
Pan Ziqiang, an expert in radiation protection and environmental protection and an academician of the Chinese Academy of Engineering, is more direct in his judgment of the application prospects of nuclear batteries. He believes that nuclear batteries can be used in some "cost-free" businesses, but they cannot enter people's lives like ordinary commodities.