Fishnet-Like, Nitrogen-Doped Carbon Films Directly Anchored on Carbon Cloths as Binder-Free Electrodes for High-Performance Supercapacitor.

Jing Wu,Qinglin Jiang,Peipei Liu,Fengxing Jiang,Liming Xu,Jingkun Xu,Weiqiang Zhou,Hui Zhang

doi:10.1002/gch2.201900086

Abstract

The low specific capacitance and energy density of carbon electrode has extremely limited the wide application of supercapacitors. For developing a high‐performance carbon electrode using a simple and effective method, a fishnet‐like, N‐doped porous carbon (FNPC) film is prepared by calcining the KOH‐activated polyindole precoated on carbon cloths. The FNPC film is tightly anchored on carbon cloths without any binder. The FNPC film with 3.8 at% N content exhibits a fairly high specific capacitance of 416 F g−1 at 1.0 A g−1. Moreover, the assembled button‐type cell with two FNPC film electrodes shows a high energy density of 16.4 Wh kg−1, a high power density of 67.4 kW kg−1, and long‐term cyclic stability of 92% of the initial capacitance after 10 000 cycles at 10 A g−1. The high performances mainly came from the integration of pseudocapacitance and electrical double‐layer capacitance behavior, wettability, fishnet‐like nanostructure, as well as the low interfacial resistivity. This strategy provides a practical, uncomplicated, and low‐cost design of binder‐free flexible carbon materials electrode for high‐performance supercapacitors.

Highlights

The low specific capacitance and energy density of carbon electrode has batteries.[1,2] The rapid development of supercapacitors is closely related to elecextremely limited the wide application of supercapacitors
The high performances mainly came from the integration of pseudocapacitance and electrical double-layer capacitance and low energy density of carbon materials count against the wide application of supercapacitors.[4,5]
Different from the above methods, we presented a facile, practical and cost-effective way to prepare a fishnet-like hydrophilic N-doped porous carbon (FNPC) film that tightly anchored on flexible carbon cloths (CC) substrate through the direct calcination of precoating polyindole (PIn) on CC

Summary

Results and Discussion

To prepare the binder-free carbon electrodes, the PIn/KOH precursor was firstly coated on CC and one-step calcinated to P-K-x carbon film. The pseudocapacitance was originated from the reversible redox conversion of oxygen functional groups or different redox states of N-5 and N-6 nitrogen existed in carbon film.[23] Compared with their CVs, the P-K-2.5 exhibited a larger CV area mainly due to P-K-2.5 had a bigger SBET and pore volume This indicated that the KOH concentration had greatly affected on the capacitance of activated carbon materials, namely, with the ratio increase of KOH and PIn, the enclosed CV areas increased firstly and decreased; the optimum ratio of KOH and PIn was about 2.5. The low Coulombic rates and current densities, the calculated specific capacitance efficiency was mainly attributed to the charge leakage occurring decreased according to different CVs and GCD curves

Conclusions

Experimental Section

Conflict of Interest