China's Betavolt New Energy Technology has unveiled a new modular nuclear battery that uses a combination of a nickel-63 (⁶³Ni) radioactive isotope and a 4th-generation diamond semiconductor and can power a device for 50 years.

Nuclear batteries may sound like something super-advanced, but they've been around in one form or another since the early 1950s. Most of these are what are called radio-thermal generators, which turn the heat from decaying radioactive elements into electricity by some sort of thermocouple or a Stirling engine.

In 2016, a new principle was introduced, which uses diamond layers doped with radioactive isotopes – in the case of the first attempt, carbon-14 (¹⁴C). The idea is to select an isotope that releases Beta (β⁻) particles, which are essentially high-energy, high-speed electrons or positrons. When these are released, the diamond matrix acts as a semiconductor to generate an electric current.