Batteries are crucial for most of bio applications. Batteries based on a liquid or polymer electrolyte needs a weight protective packaging which decreases their energy density and increases their size. This paper aims to identify, on the one hand, the efforts performed in thin-film batteries until now, and on the other hand, to provide an overview about the future perspectives in integration of batteries with flexible electronic circuits and energy harvesting systems. The overview highlights the need for an on-going investigation that aims to replace metallic lithium anode of batteries through different approaches. Other materials, namely silicon or germanium, seem promising when combined with nanostructures. Three dimensional and integrated batteries will increase its volumetric capacity.