Development of nuclear microbattery prototype based on Schottky barrier diamond diodes

We designed, fabricated, and tested for the first time a prototype of nuclear micropower battery with an overall active area about 15 cm 2 consisted in 130 single cells based on Schottky barrier diamond diodes. Diodes selection for the battery assembly was performed on the basis of I – V curves measurements at electron beam irradiation in SEM. A typical energy conversion efficiency of each cell was about 4–6%. To characterize a battery prototype performance, we carried out photovoltaic measurements using different radioisotopes. Under irradiation by 63 Ni source with activity of 5 mCi cm −2 , the output power density of 3 nW cm −2 was obtained. Due to large energy loss of the emitted β particles in source itself, the total battery efficiency was only 0.6%. However, with the long‐lived 63 Ni isotope, this already gives the battery specific energy of about 120 W · hr/kg, comparable with the commercial chemical cells. During experiments with high activity 90 Sr– 90 Y source, no degradation was observed after 1,400 h of the radiation exposure. The maximum output power density of 2.4 µW cm −2 was achieved using 238 Pu α source. The results display that synthetic diamond is a highly promising material for nuclear microbattery fabrication. A strategy to further cell optimization is also discussed.