Study On Preparation And Electrochemical Performances Of Flexible Electrodes Based On Low-Cost Carbon Felts

The key of the fabrication of flexible energy storage devices is to achieve the flexibility of the electrode and make it have environmental adaptability and chemical stability through the device packaging technology.The type,structure,and composition of electrode materials have a decisive influence on the electrochemical performance of devices.At present,most self-supporting carbon-based eletrode materials are suffering some problem of complex synthesis routes and high cost.In this thesis,flexible electrode materials with high electrochemical activities were prepared by an activation process using cheap commercial carbon felt（CF）as the raw material.Based on these flexible electrode materials,flexible supercapacitors and zinc ion batteries with excellent performance were fabricated.The main contents of this thesis are as follows:（1）Flexible activated carbon felt（ACF）materials were prepared by successive alkali solution impregnation,freeze-drying,and high-temperature calcination process with low-cost commercial CF as the raw material.Activated ACF fibers own a large number of microporous and mesoporous structures on the surface,which enhance the energy storage capacity of the material.When the ACF was tested as a supercapacitor eletrode,it’s area capacity can reach up to 1441 mF cm^-2 at the current density of 0.5mA cm^-2,which was higher than that of the similar electrode materials reported in most previous researches,showing the excellent electrochemical performance.An asymmetric supercapacitor was fabricated with MnO₂ supported carbon cloth（CC）prepared via an electrodeposition method as the positive electrode and ACF as the negative electrode,respectively.The energy density of this supercapacitor can reach up to 0.283 mWh cm^-2.In order to explore the feasibility of ACF in the practical application,polyvinyl alcohol was used to prepare gel electrolyte to further fabricate all-solid-state asymmetric supercapacitors.The energy density of this all-solid-state supercapacitor was still up to 0.104 mWh cm^-2 and maintained excellent bending stability.These results show that our ACF has a good application prospect in the preparation of flexible supercapacitors.（2）Through a cyclic vlotammetry method,the polyaniline（PANI）was further electrodeposited on ACF to prepare PANI@ACF eletrode.A zinc ion battery PANI@ACF//Zn was assembled with PANI@ACF electrode as the positive electrode and Zn plate as the negative electrode.The specific capacity of zinc ion battery was improved due to the double capacity contribution of the double-layer capacitance provided by ACF and the redox reaction of PANI.The specific capacity of PANI@ACF//Zn can up to 106.9 mA h g^-1 at the current density of 1.0 mA cm^-2.After that,Zn was deposited on carbon cloth（CC）and used to replace Zn plate as flexible negative eletrode,the assembled zinc ion battery system displayed a slightly reduced specific capacity of 105.4 mAh g^-1.Polyacrylamide was used prepare hydrogel electrolyte to further fabricate an all-solid-state zinc ion battery.At the current density of 0.3 mA cm^-2,the specific capacity of this battery was 25 mAh g^-1.These results indicate that the ACF and PANI@ACF composites have good application potentials in the flexible zinc ion batteries.