Abstract
This study aimed at exploring a diversity of aqueous bacterial biomineralisation processes at room temperature for the synthesis of electrochemically active materials for an eco-compatible and reliable Li-ion battery application. This thesis is focused on S. pasteurii bacteria assisted synthesis of amorphous FePO4·nH2O (FP). The bacterial wall induces an original organization of FP particles (called "bacteriomorph") by promoting its nucleation. The product is an electrochemically inactive composite but can be activated by multiple treatments: mechanical, chemical or thermal. Heating under air is the most efficient method, as it burns the electrically insulating bacterial matter. Bacteriomorph FP’s electrochemical performances are comparable to those of FP synthesized without bacteria but ground for several hours. This treatment is however a compromise as heating induces dehydration as well, which impairs the reversible capacity of FP. This dehydration and its consequences on electrochemical properties have been studied with multiple tools, including microscopic and spectroscopic techniques, such as STXM. To overpass the thermal activation need, we started the exploration of extracellular synthesis of MnO2 assisted by P. putida. First results are promising as the biomineral is electrochemically active without any post-synthesis activation