Preparation And Electrochemical Properties Of N-Coped Porous Carbon Sheets From Coal Tar Pitch For Supercapacitor

Supercapacitor,an ideal energy storage device with long cycle life and high power density,has attracted considerable attention.Among electrode materials,porous carbons are recognized as the promising electrode materials for supercapacitor due to the good electrical conductivity and high surface area.Doping heteroatom in carbon materials can improve electronic conductivity and enhance the wettability of electrodes.Therefore,it is of great significance to optimize the pore structure of porous carbons and improve the available specific surface area of electrolyte ions through doping nitrogen atom.In this paper,N-coped porous carbon sheets were prepared from coal tar pitch with Na C l and/or Na₂CO₃ as template coupling with K₂CO₃ or KOH activation by carbonization-activation process.The material structure and charge storage performance were analyzed.The main conclusions are as follows:(1)Layered porous carbon sheets(LPCSs)were prepared from coal tar pitch with Na Cl as template precursor coupling with K₂CO₃ activation by carbonization-activation process.The LPCS made from a mixture of 2.0 g coal pitch,5.0 g Na Cl and 10.0 g K₂CO₃ at 850°C in NH₃ atmosphere is named as LPCS_850-NH3.The specific surface area of LPCS_850-NH3 is 1198.02 m² g^-1,and the total pore volume is 0.73 cm³ g^-1.The LPCS_850-NH3-based supercapacitor shows a capacitance of 210 F g^-1 at 0.05 A g^-1,an excellent rate performance of 71.7%at 40 A g^-1,and a superior cycle capability with 95.6%capacitance retention after 10000 cycles.(2)Fold carbon nanosheets(FCNs)were prepared from coal tar pitch with Na C l and Na₂CO₃ as template precursor coupling with K₂CO₃ activation by carbonization-activation process.The FCNs made from a mixture of 2.0 g coal pitch,4.0 g Na C l,1.0 g Na₂CO₃ and 10.0 g K₂CO₃ at 850°C in NH₃ atmosphere is named as FCN₄.The specific surface area of FCN₄ reaches 1596.65 m² g^-1,and the total pore volume is 1.05 cm³ g^-1.The FCN₄-based supercapacitor shows a capacitance of 238.5F g^-1 at 0.05 A g^-1,a capacitance of 150 F g^-1 at 40 A g^-1,and a superior cycle capability with 96.9%capacitance retention after 10000 cycles.(3)Interconnected porous carbon nanosheets(IPCNs)were prepared from petroleum pitch with Na₂CO₃ as template precursor coupling with KOH activation by carbonization-activation process.The IPCNs made from a mixture of 2.0 g coal tar pitch,4.0 g Na₂CO₃,2.0 g melamine and 10.0 g KOH at 850°C in Ar atmosphere is named as IPCN₄.The specific surface area of IPCN₄ reaches 2023.28 m² g^-1,and the total pore volume is 1.14 cm³ g^-1.The IPCN₄-based supercapacitor shows a capacitance of 362.9 F g^-1 at 0.05 A g^-1,an excellent rate performance of 77.7%at 40A g^-1,and a superior cycle capability with 98.1%capacitance retention after 10000cycles.