| The tanning industry produces a large amount of solid waste every year,causing serious environmental pollution.In order to meet the needs of sustainable development and realize the healthy development of leather industry,it is of great significance to transform leather solid waste into high value.Supercapacitors have received extensive attention due to their excellent power density,long cycle life,and fast charge-discharge rates.Based on the research status of supercapacitors,this paper proposes to use leather solid waste as raw material and apply the hydrolyzate of leather solid waste to supercapacitors.In this paper,we focus on the preparation of binder-free electrodes,gelatin hydrogel-based all-in-one integrated flexible supercapacitors,and all-hydrogel supercapacitors from leather solid waste.The application of leather solid waste in the field of energy storage and the realization of high-value conversion of leather solid waste were explored.The research contents are as follows:Firstly,phosphoric acid solution was added to wet blue leather shavings to obtain waste leather shaving hydrolysate by acid hydrolysis method.Then,aniline monomers were doped with different concentrations of hydrolyzate during the polymerization process to prepare supercapacitor electrode materials.The electrode can be self-bonded on the electrode substrate without external binder and conductive agent.Electrochemical tests show that the maximum specific capacitance value of the binder-free electrode can reach 287.7 F/g at 0.1A/g,and the specific capacitance value can still maintain 67%after 5000 cycles of charge and discharge,showing good electrochemical performance.Secondly,high-performance gelatin is prepared from wet blue leather shavings.Then,an all-in-one integrated flexible supercapacitor with an obvious three-layer sandwich structure was prepared by in situ growth of polypyrrole based on the gelatin hydrogel.Based on the Hofmeister sequence,the mechanical properties of the supercapacitor were significantly improved by enhancing the hydrogel hydrophobic interaction force by the electrolyte salt solution.The fabricated all-in-one supercapacitor exhibits a high areal specific capacitance of 219 m F cm-2,a high energy density of 19.44μW h cm-2,and a long cycle life.It can maintain good electrochemical performance under bending and tensile strain and provide reliable self-healing ability.Finally,gelatin hydrogels were prepared by hydrolysis of wet blue leather shavings,and the hydrogels were doubly cross-linked by physical and chemical cross-linking methods.Subsequently,the hydrogel-based composite electrode was prepared by introducing the conductive polymer polypyrrole into the interior of the hydrogel.Finally,high-performance all-hydrogel flexible supercapacitors were fabricated by assembling the hydrogel electrode with the hydrogel electrolyte obtained by direct hydrolysis of waste leather shavings.The flexible supercapacitor can maintain stable energy output,the maximum specific capacitance can reach 426.93 m F cm-2,the energy density is 37.95μW h cm-2,and the maximum tensile strain can reach 90%,showing excellent electrochemical performance. |
