Nitrogen and sulphur-functionalized multiple graphene aerogel for supercapacitors with excellent electrochemical performance

• The study reported synthesis of nitrogen and sulphur-functionalized multiple graphene aerogel.
• The as-prepared N,S-GMA exhibits an excellent electrochemical performance.
• Its capacitance performance can be further improved by increasing number of the GO gelation cycle.
• N,S-GMA electrode in the mixed redox electrolyte displays ultrahigh supercapacitor performance.
• The study provides promising approach for building on various functional graphene materials.

Graphene aerogel has attracted increasing attention owing to its large specific surface area, high conductivity and electronic interaction. The paper reported the synthesis of nitrogen and sulphur-functionalized multiple graphene aerogel (N,S-MGA) through simple multiple gel method. The as-prepared N,S-MGA exhibits a much higher density and electronic conductivity compared with classical graphene aerogel. The density rapidly increases and resistance reduces with increasing number of the graphene oxide gelation. The unique architecture creates ultra fast electron transfer and electrolyte transport. The introduction of nitrogen and sulfur functional groups leads to additional pseudocapacitance. The N,S-MGA electrode provides high specific capacitance (486.8 F g−1 at the current density of 1 A g−1), rate capability (261.8 F g−1 at the current density of 20 A g−1) and cycling stability (lost of less 4% after 3000 cycles) in 1 M KOH electrolyte. The performance can be greatly improved by increasing number of the graphene oxide gelation. Interestingly, the addition of K3Fe(CN)6 into the KOH electrolyte can enhance the pseudocapacitance via directly contributing pseudocapacitance to N,S-MGA electrode and promoting the electron gain and loss of nitrogen and sulfur functional groups. The specific capacitance is 4929.4 F g−1 at the current density of 2 A g−1 in the mixed 1 M KOH with 1 M K3Fe(CN)6 electrolyte. The capacitance retention is more than 98.7% after 5000 continuous charge/discharge cycles, verifying good long-term cycling stability. The energy density reaches to 316.6 W h kg−1 at the power density of 683.7 W kg−1 and 117.6 W h kg−1 at the power density of 1020 W kg−1. The study also opens an avenue for the design and synthesis of functional graphene aerogel-based materials to meet the needs of further applications in energy storages/conversion devices, biosensors and electrocatalysis.

Figure optionsDownload as PowerPoint slideThe paper reported synthesis of nitrogen and sulphur-functionalized multiple graphene aerogel (N,S-MGA) through simple multiple gel method. The resulting N,S-MGA exhibits a much higher density and electronic conductivity when compared with classical graphene aerogel. Owing to significant synergy between the electrode reaction of N,S-GMA and the redox reaction of K3Fe(CN)6, N,S-GMA electrode in the mixed redox electrolyte displays ultra high supercapacitor performance.