3D nitrogen and boron dual-doped carbon quantum dots/reduced graphene oxide aerogel for advanced aqueous and flexible quasi-solid-state zinc-ion hybrid capacitors

As prospective energy storage devices,zinc-ion hybrid capacitors(ZHCs)still suffer from unsatisfactory cathode materials.Herein,the three dimensional(3D)N,B dual-doped carbon quantum dots/reduced graphene oxide(N,B-CQDs/rGO)composite aerogel is prepared via a onepot hydrothermal method.Thanks to the synergism of CQDs modification and N,B dual-doping,the resultant N,B-CQDs/rGO composite aerogel delivers superior electrochemical properties.Furthermore,the as-obtained N,B-CQDs/rGO composite aerogel is served as a cathode for aqueous and flexible quasi-solid-state ZHCs for the first time.Impressively,the aqueous N,B-CQDs/rGO//Zn ZHC manifests a large energy density of 96.2 Wh·kg^(-1)at80 W·kg^(-1)and still remains a high energy density of 54.7Wh·kg^(-1)at a superb power density of 80 kW·kg^(-1).Meanwhile,kinetic analyses are employed to elucidate the prominent power performance,and various ex situ tests are undertaken to explore the energy storage mechanism of aqueous ZHC.More notably,the flexible quasi-solid-state N,B-CQDs/rGO//Zn ZHC displays a desirable energy density(89.1μWh·cm^(-2)),a superior power density(96,000μW·cm^(-2))and exceptional flexible performance.The present study offers a valuable reference for designing and developing advanced cathode materials for aqueous and flexible quasi-solid-state ZHCs.