| Supercapacitors are a new type of rapid charge and discharge energy storage devices that have developed rapidly in recent years.Traditional supercapacitors have disadvantages such as heavy mass,large volume,and high structural rigidity.When subjected to external forces,they usually produce irreversible deformation,and serious liquid leakage may easily cause a series of safety hazards.Many new gel systems developed to solve these problems generally have the problem of being difficult to recycle,so it is urgent to solve the problem of recycling hydrogels and supercapacitors based on hydrogel electrolytes.In this paper,a regenerative hydrogel electrolyte with high ionic conductivity was prepared and applied to supercapacitors to solve the problem of device recycling.In addition,the scientific principles behind the inherent performance of this type of gel electrolyte were also studied.The main work is as follows:1.Physically crosslinked PAALi-PAH hydrogel was prepared with lithium acrylate monomer and polyallylamine hydrochloride,and PAALi-PAH/LiCl hydrogel electrolyte was prepared by soaking PAALi-PAH hydrogel in LiCl solution.The mechanical properties and ionic conductivity of the gel electrolyte can be adjusted by regulating the concentration of LiCl solution.The maximum fracture stress and strain can reach 135.5 kPa and 3039%,and the maximum ionic conductivity can reach 0.066 S cm-1.In addition,the special cross-linking mechanism of PAALi-PAH/LiCl hydrogel electrolyte makes it fast self-healing performance and excellent regenerable performance at room temperature.It can be regenerated many times through simple operation,and maintaining 96%and 90%ion conductivity after first and second regeneration,respectively,which exhibits its good application prospects.2.PAALi-PAH/LiCl hydrogel electrolyte prepared by the modified one-step method and PANI@CNTs flexible electrodes were used to prepare a flexible supercapacitor through a sandwich laminate structure.The electrochemical performance of flexible supercapacitors can be adjusted by regulating the loading of electrode active materials.The electrochemical test results show that this kind of supercapacitors have excellent cycle stability,flexibility and regenerability.The supercapacitors retain more than 99%of its initial capacity after 5000 charge-discharge cycles,reach 103.2%of its initial capacity after curling,and even the regenerated devices maintain 97.6%of its initial capacity.3.Based on anionic and cationic monomers with different side chains,different types of polyanionic and cationic hydrogel electrolytes were prepared.The effects of side chains on the mechanical and electrochemical properties of hydrogel electrolytes were examed.Tensile tests show that both the side chain structure and length have a significant effect on the mechanical properties of the hydrogel electrolyte.For hydrogel electrolytes with the same molar ratio,the fracture stress of PNa SS/PDMAEA-Q samples containing rigid groups can reach 147.1 kPa,which is much larger than that of PAANa/PAH（102.8 kPa）and PAANa/PDMAEA-Q（4.5 kPa）.At the same time,the length of the polymer side chain will affect its cross-linking effect by influencing the electrostatic shielding effect of the counter ions inside the hydrogel electrolyte,and indirectly affect the mechanical properties.The mechanical strength of PAANa/PDMAEA-Q containing longer charged side chain polycations is much lower than that of PAANa/PAH samples containing shorter side chain polycations.The ionic conductivity tests show that the side chain structure has little effect on the ionic conductivity of the polyanionic and cationic hydrogel electrolyte,and the length of the charged side chain has a greater effect on its ionic conductivity.Further electrochemical test results of supercapacitors assembled with gel electrolyte samples and PPy@CNT electrodes showed that the self-supporting properties and ionic conductivity of gel electrolytes have significant effects on the electrochemical performance of assembled devices. |
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