Preparation And Properties Of Cellulose-Based Flexible Supercapacitor Electrode Materials

Cellulose material has the characteristics of light weight,flexibility,low cost and environmental friendliness.Its rich hydroxyl structure can be used as a good conductor of electrolyte ions and has been used as a structural matrix for conductive fillers in supercapacitor electrode materials.However,due to the non-conductive nature of cellulose,its application in the field of flexible electrode materials has been limited.Therefore,this paper uses cellulose as a flexible substrate to prepare flexible supercapacitor electrodes by combining one or two of the highly conductive and electroactive substances graphene(RGO),polyaniline(PANI),nickel cobalt sulfur(NCS)for charge storage.The specific research contents and results are as follows:(1)Paper-based composite electrode materials were prepared by repeated impregnation method.The electrode materials were studied by adding RGO and PANI single component,adding two components and changing the concentration of RGO.The results show that there is a strong interaction between RGO and PANI,which can greatly improve the electrochemical performance.In addition,when the concentration of RGO is 4mg/ml,the paper-based electrode material of the prepared composite RGO and PANI has an area specific capacitance of 1151 m F/cm~2(mass specific capacitance is 287 F/g)at a current density of 1 m A/cm~2;when the current density increases to10 m A/cm~2,the area specific capacitance is 350 m F/cm~2(mass specific capacitance is 89 F/g).After 1000cycles,the capacitance retention is about 92%.(2)Cellulose aerogels were prepared by dissolution-regeneration cellulose and freeze-drying method.Cellulose composite aerogels were prepared by adding electroactive substances RGO and PANI.The effect of the mixing ratio of cellulose and RGO on the electrochemical properties of electrode materials was studied.The results show that the addition of RGO improves the pore structure of the aerogel.When the ratio of cellulose to RGO is 3:1,the prepared composite RGO and PANI aerogel electrode material has an area specific capacitance of 1824 m F/cm~2(mass specific capacitance of 445 F/g)at a current density of 1 m A/cm~2.After 5000 cycles,the specific capacitance retention is about 63%.(3)NCS powders were prepared by one-step solvothermal method.The effects of hydrothermal time at 180°C and 200°C on the morphology,structure and electrochemical properties of the powders were studied.It was found that the particle size of NCS powder was about 700-800 nm,which are prepared at 180°C and 200°C.With the increase of hydrothermal time,the particle size of the prepared powder was more uniform.In addition,the electrochemical properties of NCS powders were studied by using nickel foam as current collector.The results show that the mass specific capacitance of NCS powder prepared under the synthesis conditions of 180°C-2 h at a current density of 1 A/g reaches2032 F/g(area specific capacitance is 4 F/cm~2).The capacitance retention is 71%after5000 cycles.(4)The flexible electrode composites were prepared by dispersing nanocellulose,RGO and NCS powder prepared at 180°C-2 h through dispersion blending-filtration.The experimental results show that the mass specific capacitance can reach 689 F/g at a current density of 1 A/g.The flexible composite electrode material has no obvious attenuation of capacitance after bending test at different angles.