The Modification And Electrochemical Properties Of Carbon Cloth

Supercapacitors with long cycle life,low price and high power density have been widely used in the energy storage field.The carbon cloth,which has excellent conductivity and mechanical flexibility,has strong potential as support/current collector for flexible supercapacitor.However,the low specific surface area and capacitance limit their application.Therefore,this research focuse on improving the specific surface area and conductivity of the carbon cloth.The electrochemical properties are greatly improved through coating the nitrogen-doped carbon.?1?Sodium azide-assisted hydrothermal method was employed to improve conductivity of active caobon and carbon cloth.Adsorption desorption experiment confirmed that the N-doped active caobon?NAC?possesses a high specific surface area of 1903 m²/g.The existence of nitrogen element on the surface of carbon cloth not only improved the conductivity but also enhanced the capacitance.The Faradaic interfacial charge-transfer resistance(R_ct)was as low as 2.2?and the capacitance of NAC electrode could be 51 F/g at a current density of 1 A/g.The surface area of the N-doped porous carbon cloth?NPCC?was 52 m²/g.The NPCC device delivered a high areal capacitance of 130 mF/cm² at a current density of 1 mA/cm²,and the highest volumetric energy density of 2.03 mWh/cm³ was achieved at a volumetric power density of 0.375W/cm³.Additionally,the device could retain 95.8%of its initial capacitance even after30000 cycles at the current density of 2.5 mA/cm²,showing excellent electrochemical properties.?2?The N-doped porous carbon was prepared directly from the carbonization of polypyrrole?PPY?,which has a high surface area of 2256 m²/g.A device was assembled by using the N-doped porous carbon as the positive and negative electrodes and LiClO₄/AN as electrolyte.The capacitance of the device could be 62 F/g from potential range of 0-1.25 V,at the current density of 0.5 A/g.When the potential window was increased to 0-2V,the device has a capacitance of 112.5 F/g,at the current density of 0.5A/g.As the device was further tested by using the 1-ethyl-3-methylimidazole tetrafluoroborate as electrolyte.The capacitance was found to be 39.25 F/g in a broad window of 0-4 V at the current density of 0.5 A/g,corresponding to a high energy density up to 87.2 Wh/kg.?3?The nitrogen-doped carbon was coated on the surface of carbon cloth?NCC?to improve the surface.The specific surface area of the NCC was 147 m²/g.The NCC had a high specific capacitance of 1.2 F/cm² at 8 mA/cm² and excellent cycling stability with no visible decrease after 50000 cycles.An asymmetrical supercapacitor?ASC?was assembled by using MnO₂@NCC?MNCC?and NCC as the positive and negative electrodes.The flexible?ASC?delivered a high capacitance of 350 mF/cm² at 3mA/cm².The ASC devices were charged and then connected to power 16 light-emitting diode indicators for 8 min.Furthermore,the device can be bent and twisted without performance degradation,suggesting the good flexibility and stability.The porous carbon film was coated on the surface of porous carbon cloth?PCC@NMC?to improve the specific surface area.The PCC@NMC showed a specific surface area of 244 m²/g.The PCC@NMC electrode had a high specific capacitance of 2.2 F/cm² at 8 mA/cm².An ASC was assembled by using PCC@NMC as negative electrodes.The flexible?ASC?delivered a high capacitance of 600 mF/cm² at 4 mA/cm².The ASCs were charged and then connected to power 32 light-emitting diode indicators for 16 min.?4?The porous carbon film was deposited on the surface of carbon cloth?NCF?to improve the specific surface area.The specific surface area of NCF was measured to be84 m²/g.The NCF was treated in sodium azide solution at a hydrothermal environment to obtain a dual N-doped NCF?NNCF?with enhanced conductivity.The first discharge capacity of the NNCF electrode at 1 mA/cm² was 5.1 mAh/cm².The full device exhibited a high discharge capacity of 0.2 mAh/cm² at 0.2 mA/cm².The device with different bending angles delivered similar GCD curves,and the capacity was nearly unchanged.These findings revealed the excellent stability of the flexible LIB device.