Résumé
Ion adsorption and dynamics in porous carbons are crucial for many technologies, such as energy storage and desalination. Progress in the development of novel systems is hampered by our lack of understanding of the microscopic mechanisms that determine their behaviour and performance. The key issue is that phenomena on the atomistic scale have consequences on macroscopic length and timescales. In particular, the effects of ionic confinement and diffusion are crucial for device performance, yet experiments that probe properties related to local structure and diffusion are challenging and difficult to interpret without a parallel modelling approach. I will present a multi-scale approach designed to bridge the gap between molecular simulations (corresponding to length scales of a few nanometers) and experiments (here length scales of a few micrometers). The mesoscopic models developed, versatile and very computationnally efficient, allow one to predict useful quantities, such as NMR spectra, tortuosities, and quantities of adsorbed ions, for electrolyte species adsorbed in disordered porous carbons. I will show how this approach can be used to gain insights into the structure of porous carbons [1][2] and simulate in situ NMR spectra of electrolyte ions adsorbed into carbon electrodes maintained at a given potential difference [3]. The simulation of electrolyte species adsorbed in nanoporous carbons is especially relevant for electrochemical double layer capacitors (also called supercapacitors), energy storage systems in which the energy is stored at the carbon-electrolyte interface. Recently, major improvements in the code implementation have allowed us to reach even larger scales (several hundreds of nanometers), allowing for the simulation of carbon particles with different sizes and full supercapacitors [4].