Effect of N-doping-derived solvent adsorption on electrochemical double layer structure and performance of porous carbon

Abstract

N-doped porous carbon has been extensively investigated for broad electrochemical applications. The performance is significantly impacted by the electrochemical double layer (EDL), which is material dependent and hard to characterize. Limited understanding of doping-derived EDL structure hinders insight into the structure–performance relations and the rational design of high-performance materials. Thus, we analyzed the mass and chemical composition variation of EDL within electrochemical operation by electrochemical quartz crystal microbalance, in-situ X-ray photoelectron spectroscopy, and time-of-flight secondary ion mass spectrometry. We found that N-doping triggers specifically adsorbed propylene carbonate solvent in the inner Helmholtz plane (IHP), which prevents ion rearrangement and enhances the migration of cations. However, this specific adsorption accelerated solvent decomposition, rendering rapid performance degradation in practical devices. This work reveals that the surface chemistry of electrodes can cause specific adsorption of solvents and change the EDL structure, which complements the classical EDL theory and provide guidance for practical applications.