Nitrogen-doped porous carbon nanosheets as both anode and cathode for advanced potassium-ion hybrid capacitors

Abstract

Potassium-ion hybrid capacitors (PIHCs) as a burgeoning research hotspot are an ideal replacement for lithium-ion hybrid capacitors (LIHCs). Here, we report nitrogen-doped porous carbon nanosheets (NPCNs) with enlarged interlayer spacing, abundant defects, and favorable mesoporous structures. The structural changes of NPCNs in potassiation and depotassiation processes are analyzed by using Raman spectroscopy and transmission electron microscopy. Due to the unique structure of NPCNs, the PIHC device assembled using NPCNs as both the anode and cathode material (double-functional self-matching material) exhibits a superior energy density of 128 Wh kg−1 with a capacity retention of 90.8% after 9000 cycles. This research can promote the development of double-functional self-matching materials for hybrid energy storage devices with ultra-high performance.