Diamond batteries that can generate power for 100 years are being considered for use in space probes and underground mining equipment.
These batteries use synthetic diamonds to produce electricity when exposed to radiation. If the radiation can be safely contained by wrapping the batteries in aluminum or other metal plates, they could be commercially viable.
Satoshi Koizumi, head of the Wide Bandgap Semiconductor group at Japan’s National Institute for Materials Science, said, “This is a beautiful crystal. We can unlock the potential of diamonds.”
Diamonds are among the hardest materials on Earth and are widely used in industry. They can even be turned into semiconductors. The team created a simple P-N junction diode by attaching a thin diamond film to a diamond base to generate electricity.
Diamond batteries, also called betavoltaic batteries, generate power as long as they remain in a radiation field, harvesting beta particles from isotopes like carbon-14 and nickel-63. Their long lifespan comes from the slow decay rates of these isotopes, with half-lives of about 5,700 years and 100 years respectively.
Using silicon carbide (SiC), several American and other companies have already brought betavoltaic batteries to market. Although diamonds have even higher thermal conductivity than silicon carbide, making diamond semiconductors is much more challenging.
The diamond batteries developed by NIMS are the result of decades of research and expertise accumulated since the 1990s. Their material’s thermal conductivity is around 28%, the highest in the world and close to the theoretical limit at the elemental level.
The NIMS team initially used electrons from devices like electron microscopes instead of beta particles to generate electricity, but they now plan to use nickel-63.
A major challenge remains to improve the battery’s efficiency by increasing its power output. Currently, these batteries only produce power at the microwatt level (1μW equals one millionth of a watt).
Still, the potential for synthetic diamond batteries is huge. In 2020, the UK Atomic Energy Authority and the University of Bristol announced research into using carbon-14, an isotope commonly found on graphite surfaces during nuclear power production. These isotopes can be recovered when nuclear plants are decommissioned.
The UK is exploring making diamond batteries from materials salvaged during plant dismantling. While details are scarce, success could mean power sources lasting thousands of years.
Nuclear batteries that use heat from radioactive elements like plutonium are often used in space probes. Though they generate relatively high power, handling plutonium safely is very difficult.
In contrast, diamond batteries can withstand high temperatures, have simpler designs, and are safer.
Koizumi from NIMS said, “They can operate even at high temperatures, making them suitable for space devices, mineral exploration tools, and other equipment.”
Research into diamond batteries opens exciting possibilities for the future of energy and space industries.
Source: Nikkei
