Flexible Supercapacitor Device Based On Textured Carbon Cloth And PET Substrate

As one of promising electrochemical energy storage device,supercapcitor has attracted extensive attentions because of its high power density,very short charging/discharging time,long cycle life and wide-range operating temperature.With the rapid development of portable and wearable electronic devices,flexible supercapacitor can be integrated with various flexible consume electronics to provide energy supply.Flexible electrode plays a crucial role in determining the overall properties of all-solid-state supercapacitor.With cotton fabrics as the starting materials,we have successfully prepared highly conductive porous carbon fiber textiles by high-temperature carbonization and KOH chemical activation.The effects of KOH amount on the structures and properties of carbon fiber textile were systematically investigated Results show that KOH activation process can produce abundant micro/mesoporous and surface oxygen functional group on the backbone of carbon fibers,which are found to facilitate the wettability and improve the ion-accessible surface area of electrode and the electrolyte.The specific surface area of the porous carbon fiber reaches 1075 m2/g,the corresponding pore volume is about 0.59 cm3/g,and the electrical conductivity is as high as 1506 S/m.When used as the supercapacitor electrode,the area capacitance of the carbon fiber textile reach a high value of 1026 mF/cm2 with a capacitance retention of 85%when the current density increases from 5 to 100 mA/cm2.These performances are far superior than the commercial carbon cloth(only 14 mF/cm2 with a capacitance reteLtion of 64%in the same current range).A supercapacitor cell built with the carbon fiber textile as electrode and PVA/KOH as gel electrolyte show high cycling stability with only 3%capacity decay after 10000 continuous charge-discharge cycles.Moreover,an energy density of 17.9 jpWh/Crrcm at the power density of 459.8?W/cm2,together with good mechanical flexibility.With PET as flexible substrate,we first fabricated interdigital microelectrodes through lithography and electron beam evaporation technology.Then rGO and CoS were successively deposited by electrochemical deposition to form a rGO/CoS composite electrode.The characterization results show that rGO on the interdigital microelectrodes display two-dimensional planar structure with slight wrinkle,which favors the nucleation of subsequent CoS and promots fast and barrier-free transfer of electrons.Area specific capacitance of rGO was measured to be 1.3 mF/cm2 at a scanning rate of 1 V/s and 1.0 mF/cm2 at a ultra-high scanning rate of 50 V/s.The CoS deposited on rGO buffer layers displays nanosheets structure with more exposed surface area.As a result,area capacitance is increased to 22 mF/cm2 with a capacitance retention of 74%as the current density increased from 0.1 to 2.0 mA/cm2.These results showed that rGO/CoS composite electrode materials can make full use of the pseudocapacitive CoS and fast charge transfer ability of rGO,leading to to an overall improvement of the performance.