In the global context of massive renewable energy deployment, production and storage are becoming increasingly intertwined. Battery electrochemical energy storage systems (BESS) are currently experiencing strong market growth. These systems differ radically from electric mobility solutions due to their specific characteristics (cost, safety, durability). Faced with the limitations of Li-ion batteries (fire risks, the criticality of lithium and cobalt, production costs), aqueous zinc/sodium-ion technology presents a disruptive alternative. Based on abundant, non-toxic, and inherently safe materials, it offers unique potential for long-term storage with a low environmental impact. The zinc battery sector faces scientific challenges that limit reversibility and cycle life, notably the formation of zinc dendrites and cathode instability. This doctoral thesis project proposes to overcome these obstacles through a research and development strategy for innovative electrodes based on the reversible transformation of zinc into zinc phosphate in an aqueous sodium phosphate medium. This choice of electrolyte allows the use of sodium-ion positive electrodes as well as AGM (absorptive glass mat) separators, developed notably for lead-acid batteries.
The thesis work will focus on experimental electrochemical studies combined with multiphysics modeling of the system at the cell scale, taking into account the thermodynamics and kinetics of the included reactions. This approach will allow for the rapid exploration of a vast design space to identify the conditions enabling scaling up and transfer to industry, meeting the imperatives of energy sovereignty and the circular economy.