The race to develop miniature, modular nuclear-powered batteries is being led by Betavolt New Energy Technology. The China-based company plans to market the devices to meet power supply needs in aerospace, medical, sensor and other applications.

The radioisotope battery generates current through the semiconductor transition of beta particles emitted by the decay of nickel-63. A unique single crystal diamond semiconductor with a thickness of only 10 microns and dielectric breakdown strength and thermal conductivity superior to that of silicon carbide devices was engineered for inclusion in the battery.

A 2-micron-thick nickel-63 sheet is placed between two diamond semiconductor converters to convert the decay energy of the radioactive source into electric current and form a separate unit. The nuclear batteries can be composed of dozens or hundreds of independent unit modules, and can be used in series and in parallel, enabling the manufacture of battery products of different sizes and capacities.

The energy density is more than 10 times that of ternary lithium batteries, and the potential for 50 years of self-generating power implies a virtually unlimited number of charge and discharge cycles. According to Betavolt, the device emits no external radiation and delivers stable performance in the 120° C to -60° C temperature range.

The first nuclear battery to be mass-produced will have a power output of 100 μW and a voltage of 3 V in a 15 mm³ module.