A Chinese startup has unveiled a new battery that it claims can generate electricity for 50 years with the need for charging or maintenance.

Beijing-based Betavolt said its nuclear battery is the first in the world to realise the miniaturisation of atomic energy, placing 63 nuclear isotopes into a module smaller than a coin.

The company said the next-generation battery had already entered the pilot testing stage and will eventually be mass produced for commercial applications like phones and drones.