Alternative power sources for space exploration: 55Fe X-ray-voltaic batteries

The duration and mission of space explorations are primarily determined by the performance of power sources. The X-ray-voltaic batteries recently emerged as one of the most promising power sources for extreme environments due to their super long lifetimes, extremely high energy densities, and high theoretical efficiencies. Therefore, it is necessary to conductive a comprehensive investigation on the structure design and semiconductor selection to fully reveal the potential of X-ray voltaics. In this work, 55Fe X-ray voltaic batteries with high energy conversion efficiency and their applications have been demonstrated as alternative clean power sources for space explorations. Comprehensive investigation has been conducted to study the impacts of the structure parameters of conversion units and the intrinsic properties of different semiconductors on the energy conversion efficiency of the X-ray-voltaic batteries. A GaAs-based 55Fe X-ray-voltaic batteries with the optimal structure can achieve the highest energy conversion efficiency of 14.14 %, the output power of 16.50 μW/cm2, and a specific energy density of 2.70 × 103 W·h/kg, which is significantly higher than that of lithium-ion batteries and fuel cells. This GaAs-based battery was demonstrated as a continuously power for micro-LEDs and intermittent power for a wireless camera system. This study reveals the promising potential of X-ray-voltaics batteries as an alternative clean power source for space exploration, which will inspire the further development of isotope batteries in practical applications.