▎ 摘　　要

Revealing microscopic real-time ion transport behavior is critically-important for understanding the charging mechanisms of polymer electrolytes. Herein polymer dominated ion charging mechanism of LiCl/polyvinyl alcohol (PVA) gel polymer electrolytes within graphene nanochannels is observed by combined electrochemical quartz crystal microbalance (EQCM) and molecule dynamics (MD) simulations. This is substantially different with the conventional aqueous electrolytes, demonstrating the dominated role of PVA polymer (including polymer-ion and polymer-electrode interactions) in mediating the charging mechanisms. Specifically, in-situ EQCM measurement reveals that -OH polar groups of PVA exhibit more significant hindrance to cations than anions, yielding the charging mechanisms from Li+ adsorption/desorption (at 0 wt % PVA) to Li+/Cl- ion exchange dominated transport (at 40 wt % PVA). Furthermore, ionic flux is quantitatively characterized based on the non-equilibrium thermodynamics, and the charging resistance is revealed via combining constant potential method and equivalent electric circuits. More importantly, increasing PVA concentration remarkably affects the thermodynamic properties (e.g., dielectric property, angle distribution and number density), while almost identical capacitance is recognized because of higher dielectric constant of PVA molecules. By solving Poisson equation, this is further interpreted and invalidated by quantifying the contributions of ions, solvents and PVA molecules to the electric potentials.