Water-in-salt electrolyte ion-matched N/O codoped porous carbons for high-performance supercapacitors

Pore size and distribution in carbon-based materials are regarded to be a key factor to affect the electrochemical capacitive performances of the resultant electrodes.In this study,nitrogen and oxygen codoped porous carbons（NOPCs） are fabricated based on a simple Schiff-base reaction between m-phenylenediamine and terephthalaldehyde.The NOPCs have tunable morphologies,high surface areas,abundant heteroatom doping.More importantly,the carbons show a dominant micropores of 0.5-0.8 nm,comparable to the ionic sizes of LiTFSI（Li;0.069 nm;TFSI-0.79 nm） water-in-salt electrolyte with a high potential window of 2.2 V.Consequently,the fabricated symmetric supercapacitor gives a high energy output of 30.5 Wh/kg at 1 kW/kg,and high stability after successive 10,000 cycles with ～96.8% retention.This study provides promising potential to develop high-energy supercapacitors.