Hydrangea -like N/O codoped porous carbons for high-energy supercapacitors

Carbons with specific morphologies, compositions and structures have aroused scientific and technological interest due to their intriguing and overwhelming properties for multi-purpose applications. Herein, a novel route to convert Knoevenagel copolymer into hydrangea-like, N/O codoped, and high-surface-area porous carbon (HPC) spheres with excellent supercapacitive performances is presented. By crosslinking p-phenylenediacetonitrile with two aromatic aldehyde co-monomers, as-prepared material exhibits a unique architecture of intertwined nanosheets uniformly self-assembled on the surfaces of microporous spheres. Featuring a large adsorbing platform (1963 m(2) g(-1)), multi-scale pore structure and diverse N/O functional groups, HPC electrode carbonized-activated at the optimal temperature of 700 degrees C yields a prominent capacitance of 330 F g(-1) at 1 A g(-1), along with a satisfactory rate capability of 221 F g(-1) at 20 A g(-1) in KOH electrolyte. More importantly, taking advantage of a refined interphase between the high-concentration water-in-salt Li-TFSI layer and the ion-accessible hydrangea surface, HPC-based supercapacitor gives a higher energy delivery of 32.9 Wh kg(-1) at 575 W kg(-1) than the common devices using KOH (10.93 Wh kg(-1) at 100 W kg(-1)) and Na2SO4 (24.9 Wh kg(-1) at 180 Wkg(-1)), with high-voltage aqueous durability of 90.5% retention over 10,000 cycles at 2.3 V. This inspiring work enriches the methodology for fabricating functionalized carbon spheres that are expected to boom diverse applications.