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

Lithium-ion capacitors (LICs), by integrating the merits of batteries and supercapacitors, can improve energy/power density compatibly. However, the current understanding of the structure–property–performance relationship has limited the further development of carbon-based electrodes. Here we discuss how the architecture of interlayer channels influences the ion accessibility and selectivity in N-doped porous carbon (NDPC) cathodes. Electrochemical and spectroscopic measurements reveal that large interlayer channels provide high permeability for different anions and rearrange to buffer the volume variation. Conversely, narrow slits show high ion selectivity and suffer from distortion interacting with large anions. The turning point is the tuned channel size after the carbon layer rearrangement in the soaking process. Contrary to the popular opinion that pore size dominates capacitive behavior while d-spacing determines the intercalative process, we demonstrate the importance of interlayer spacing in electrical double-layer mechanism for NDPCs. This size effect is also successfully put into practice for developing advanced LICs.