A Research On Energy-storage Characteristics Of Electrodes Based On Biomass And Its Derivatives

Electrochemical energy-storage devices play extremely important roles in modern life and are widely used in many fields such as portable consumer electronics,transportation and grid balancing.However,limited by the reserves of mineral resources and degradability,traditional electrode materials could hardly satisfy the needs of the green and sustainable development.Therefore,safe,biodegradable and sustainable energy-storage materials will dominate the next-generation power sources,of which renewable redox-active biomolecule-based electrode materials with high theoretical capacity performance could be a promising class of candidate.In this article,we mainly investigated the energy-storage characteristics of the juglone-based composite material and its derived polymer materials.The main research contents in this article are as follows:(1)We fabricated juglone/activated carbon composite materials by physical blending.The effects of component ratio and process parameters on the performance of the composite materials were investigated.We characterized the morphology and structure of the prepared electrodes by scanning electron microscopy(SEM)and Fourier transform infrared spectroscopy(FTIR).The electrochemical properties of the composites were tested by cyclic voltammetry(CV),galvanostatic charge-discharge(GCD),and electrochemical impedance spectroscopy(EIS).The results showed that the specific capacitance of juglone/AC composite electrodes can reach 248 F/g at a current density of 1 A/g and the coulombic efficiency reached 89.9% when m(juglone): m(AC)= 1:3.The AC granules worked as scaffolding to support and strengthen the slight biomolecules,thus expanding the contact area between the active sites and electrolyte and effectively inhibiting the dissolution into electrolyte of the active materials.Besides,the contact resistance between the active material and the electrolyte reduced because of the good conductivity of the activated carbon.Furthermore,a coin-type asymmetric supercapacitor device based on this composite electrode was assembled with AC electrode as the counter electrode and reversibly cycled at a voltage of 1.2 V.The device provided a specific capacitance of 37.7 F/g at a current density of 0.6 A/g and the corresponding energy density can reach 7.5 Wh/kg.(2)The activated carbon/polyaniline and juglone/activated carbon/polyaniline composite electrode materials in supercapacitors were synthesized by in-situ chemical oxidative polymerization.The impacts of polymerization conditions and component ratio on electrochemical performance of juglone/AC/PANI composites were investigated.And the surface performance and electrochemical properties of the composite materials were characterized.The results showed that the specific capacitance of the composites can reach 307.6 F/g at a current density of 1 A/g.At the same time,the electrochemical performance could obviously enhanced by appropriately increasing the concentration of acid and the amount of activated carbon used in the polymerization process.Furthermore,a coin-type asymmetric supercapacitor device based on this composite electrode was assembled with AC electrode as the counter electrode and reversibly cycled at a voltage of 1 V.The device provided a specific capacitance of 57.8 F/g at a current density of 0.5 A/g and the corresponding energy density can reach 8 Wh/kg.(3)The juglone-based polymer materials were synthesized through heating in water bath.The influence of processing conditions such as polymerization temperature and component ratio on the performance of products was investigated.We characterized the morphology and molecular structure of the prepared polymer materials by scanning electron microscopy(SEM),Fourier transform infrared spectroscopy(FTIR)and thermogravimetric analysis(TGA).And the electrochemical properties of the polymer electrodes were also researched.The results showed that the juglone-based polymer materials had a specific capacitance of 74.7 F/g and had improved solubility and thermal stability compared to the monomer.