Design and evaluation of a high-performance betavoltaic battery utilizing vertically stacked diamond matched 90Sr source

In this work, a new design scheme for a high-performance betavoltaic battery utilizing a vertically stacked diamond matched 90Sr source was proposed. The energy converter consisted of multiple self-supporting ultra-thin Al-diamond Schottky diode units in parallel connection and distributed on both sides of a high-energy 90SrTiO3 beta source. The output performance of the battery was evaluated through the comprehensive model constructed by employing the Geant4 code of the Monte Carlo method and COMSOL Multiphysics of the finite element method. The self-absorption effect of the 90SrTiO3 source and energy deposition distribution in the diamond material was analyzed. The structure of a single Al-diamond Schottky diode unit was optimized to achieve high charge collection efficiency and obtain a high open-circuit voltage. The evaluation results of battery performance under different source efficiencies and unit thicknesses showed that, with a source efficiency of 50% and a unit thickness of 5 μm, the battery could achieve a high-power density of up to 622 μW/cm3. However, the optimal overall efficiency of 0.46% was obtained at the source efficiency of 90% and the same unit thickness. This work provides an important solution for the development of high-performance betavoltaic batteries.