Constructing graphene-coupled nitrogen-doped carbon-based all-carbon hybrid for hybrid Li-ion supercapbattery: An investigation and insight into "charge-averaged" charge/discharge voltage analysis

Highlights: • Fabrication of porous graphene-coupled N-enriched amorphous carbon network (PNCG). • PNCG with surface area of 2430 m²/g with a N-doping of 4.3 at%. • Micro/meso pores-dominated PNCG aid in rapid Li-ion diffusion. • PNCG showed capacity retention of 94.2% (147.9 mAh/g at 500 cycles). • Insights into 'charge-averaged' charge/discharge of Li-ion supercapbattery. -- Abstract: We report on facile preparation and surface functionality-driven Li-ion storage characteristics of porous nitrogen-enriched carbon with nanoscaled graphene (NG) network (PNCG). In-situ nitrogen-doped polymer-derived amorphous carbon-coated on NG was prepared and subsequently, transformed into porous carbon with pyrogenic-agent assisted activation in boosting the charge storage by creating super pathways-rich interconnected and channelized network to facilitate rapid ion-transport. PNCG possesses a BET surface area of 2430 m²/g with a nitrogen doping of 4.32 at%. PNCG presented a capacity of 188.8, 172.9, 156.9 and 135.4 mAh/g at the discharge current density of 0.2, 0.5, 1.0 and 2.0 A/g, respectively. Furthermore, it presented a discharge capacity of 147.9 mAh/g after 500 cycles at a current density of 1.0 A/g with a retention of 94.2% capacity demonstrating exceptional cycle stability. This study provides insights into the contribution of nitrogen inclusion, NG-restacking avoided network and disordered-structured defected sites-driven Li-ion storage capability, which may drive advancing the application of PNCG as cathode (positive) electrode material for hybrid Li-ion supercapbattery.