ElectroMecano

Electrolytes have a major role to play in low-carbon energy, not only for its storage (supercapacitors, batteries, fuel cells) but also for its harvesting (osmotic energy). However, poor control of electrolyte transport under confinement (in nanoporous electrodes or membranes) limits the development of these technologies. Close to a charged surface, electrostatic interactions lead to an equilibrium ion distribution (electrical double layer), and this non-electroneutral interfacial layer induces the coupling of transport modes, i.e., the generation of hydrodynamic, electrical and ionic flows by pressure, potential and concentration gradients (electrokinetic couplings). The scientific ambition of ElectroMecano is to achieve a fundamental understanding of the physics of transport in nanoconfined electrolytes. The strategy for overcoming this scientific bottleneck is to probe nanoconfined electrolytes using an original instrument to measure “ElectroMechanical Impedance Spectroscopy”. The principle consists in nanoconfining an electrolyte between two macroscopic and conductive surfaces, and to combine mechanical and electrical measurements. This approach will allow to reach the project’s objectives, because it ensures (i) a model geometry of confinement, and (ii) simultaneous measurement of equilibrium and transport. The simplest models, based on a continuous description of matter and on a mean-field treatment of electrostatic interactions, will be tested experimentally for the first time. Refined models will be built to describe situations involving molecular confinement, large surface potentials, high concentrations and specific effects which are commonly met in applications, and the validity domains of the different models will be determined.