Photovoltaically rechargeable fuel cell accumulator for energy self-sufficient microsystems

Energy self-sufficient microsystems equipped with a micro energy harvester also need an adequate energy storage device with a high energy density to guarantee reliable and long-lasting operation. A combined system which can tap and store ambient energy as well as deliver constant and continuous electrical power is desirable. Therefore we have developed a novel fuel cell type accumulator with an integrated photoactive ceramic which allows photovoltaic charging. The button cell shaped system exhibits a metal hydride (MH) storage of high energy density and a semiconductor consisting of a pressed strontium titanate (STO) ceramic. We have demonstrated that the MH storage can be photocharged upon illumination and subsequently discharged by using an external load. Furthermore, we have developed electrophoretically deposited STO films which have shown much higher photo activity than pressed bulk ceramics.