An Interlayer Spacing-Anion Matching Guideline for High-Performance N-Doped Porous Carbon Cathode

Lithium-ion capacitors (LICs), byintegrating the meritsof batteriesand supercapacitors, can improve energy/power density compatibly.However, the current understanding of the structure-property-performancerelationship has limited the further development of carbon-based electrodes.Here we discuss how the architecture of interlayer channels influencesthe ion accessibility and selectivity in N-doped porous carbon (NDPC)cathodes. Electrochemical and spectroscopic measurements reveal thatlarge interlayer channels provide high permeability for differentanions and rearrange to buffer the volume variation. Conversely, narrowslits show high ion selectivity and suffer from distortion interactingwith large anions. The turning point is the tuned channel size afterthe carbon layer rearrangement in the soaking process. Contrary tothe popular opinion that pore size dominates capacitive behavior while d-spacing determines the intercalative process, we demonstratethe importance of interlayer spacing in electrical double-layer mechanismfor NDPCs. This size effect is also successfully put into practicefor developing advanced LICs.