Tuning N-doped configurations of N-enriched porous carbon nanosheets for high-performance zinc ion storage
Aqueous zinc ion capacitors(ZICs)composed of porous carbon cathode and Zn metal anode have attracted great research interest in recent years due to their advantages of low cost,environmental friendliness,high safety,and long-term durability.This work first synthesized a N-containing polymer as the precursor by condensation of melamine chloride and p-phenylenediamine,and then fabricated N-enriched porous carbon nanosheets(NPCN-x)with a high N content(>10%)by a carbonization and self-activation strategy.The influence of carbonization temperature on the morphology,microstructure,surface chemical properties,and electrochemical performance of NPCN-x was investigated in detail.The results showed that carbonization temperature had a significant regulation effect on the N-doped configurations.It was revealed that the pyrrolic N configuration within NPCN-x materials played a crucial role in improving their electrochemical performance.As a consequence,the optimized NPCN-800 sample with the highest pyrrolic N content of 2.15%delivered a high specific capacity up to 158mAh/g at 0.5A/g and excellent cycling performance as the cathode for ZICs.To further explore the storage mechanism of Zn ions on the N-doped carbon surface during the electrochemical process,density functional theory(DFT)calculations were performed,which showed that the pyrrolic N configuration possessed the strongest adsorption capability for Zn ions,suggesting superior electrochemical activity in comparison to other N-doped configurations.This work provided a new insight from both theoretical and experimental perspectives for constructing porous carbon materials for high-performance ZICs.
porous carbon nanosheetsN-doped configurationszinc ion storageelectrochemistryoptimal design