Abstract
This thesis is part of the current industrial dynamics of research on all-solid-state batteries in which Renault Group is particularly involved. For a democratization of electric vehicles, automotive groups must develop batteries with always greater autonomies. One of the solutions is the use of lithium metal as negative electrode, which would considerably increase the battery's capacity. However, a solid electrolyte is necessary for the proper operation of this technology, capable of inhibiting the dendritic growth on the surface of lithium.This thesis aims to study solid polymer electrolytes (SPEs) which, to date, present ionic conductivities at room temperature much lower than those of liquid electrolytes or inorganic electrolytes. Nevertheless, these SPEs would allow an easier shaping and processability, applicable on an industrial scale. We have shown in this thesis the potentiality of nitrogen-rich polymers used as solid electrolytes, with the case of poly(ethylene imine) (PEI) and poly(oxazoline) (POx). It is difficult for a single polymer to meet all the required characteristics, that is why we propose here several ways of improvement i) by mixing polymers, ii) by copolymerization, iii) by the organization in semi-interpenetrated networks or iv) by the elaboration of composite electrolytes. These different strategies have allowed to obtain polymer electrolytes PEI-based with mechanical integrity, electrochemical stability and ionic conductivity comparable to those of the state of the art. Another aspect of this thesis was the understanding of the lithium conduction mechanisms, poorly described in the literature for nitrogenous polymers, thanks to the use of DFT modelling in support of infrared and solid-state NMR spectroscopies.