Application Of Multifunctional Hydrogel Electrolyte In Electrochemical Energy Storage

As an important aqueous energy storage device,supercapacitors have attracted much attention due to their long cycle life,high power density,and fast charging and discharging speed.The device contains three parts:a positive electrode,a negative electrode,and electrolyte.The electrolyte,as a medium for transporting electrons and ions,plays a pivotal role in the energy storage process.Gel electrolytes have been widely studied for their combination of high ionic conductivity of liquid electrolytes and stability of solid-state electrolytes.Traditional hydrogel electrolytes are usually composed of polymer backbones and liquid electrolytes.However,traditional gel electrolytes have poor electrical conductivity(the ionic conductivity is usually less than2 S m^-1)and unsatisfactory mechanical properties,which are not enough to cope with the complex working environments that flexible devices face,such as extreme temperatures,compression,and bending.Therefore,optimizing the design of gel electrolyte components,developing multifunctional hydrogel electrolytes,and improving their electrochemical performance are the current research hotspots,it is also the research direction of this paper.The main research of this paper is as follows:（1）In the experimental system of Chapter 3:In the third chapter experimental system:by doping supramolecular gel in the polymer gel framework,a gel electrolyte with potassium ion transport channels was constructed.The addition of reversible hydrogen bonds and boron ester bonds enables the gel electrolyte to have good self-healing properties and mechanical properties.Supramolecular PVA-GB hydrogel electrolyte containing potassium ion channel was successfully prepared by utilizing the properties of potassium ion channel constructed by Guanosine（G）combined with polyvinyl alcohol（PVA）hydrogel with good biosafety,the symmetric supercapacitor device based on PVA-GB-112 mg hydrogel electrolyte exhibits a specific capacitance of209.1 F g^-1 at a current density of 0.8 A g^-1.The gel has a high ionic conductivity of 70ms cm^-1 and a rapid self-healing ability.This work successfully constructed a multifunctional supramolecular hydrogel electrolyte containing potassium ion channels,which provides a decent method for the construction of ion channels/channeled hydrogel electrolytes in the future.（2）In the experimental system of Chapter 4:Experiments are designed for the problems of poor conductivity and narrow application temperature range of traditional gel electrolytes.First,by introducing an anionic backbone into polyvinyl alcohol,not only the conductivity of the gel but also the electrolyte voltage range is increased.Second,the freeze resistance of the gel was increased by introducing ethylene glycol（EG）.The anionic organic hydrogel PVA-CMC-LC prepared in this chapter has excellent ionic conductivity:8.3 S m^-1 at room temperature and excellent mechanical properties,the assembled supercapacitor has an operating voltage of 1.5 V,and its capacitance is The density is 0.8 A g^-1 up to 320 F g^-1,and the energy density is 24.3 Wh kg^-1.At the same time,its functional performance is frost resistance.Its ionic conductivity over a wide temperature range is 3.18 S m^-1 at-40 ^oC and 9.67 S m^-1 at 60^oC.In conclusion,this study successfully prepared an anionic organohydrogel electrolyte with antifreeze and strong practical application.（3）In the experimental system of Chapter 5:Similarly,starting from the preparation of antifreeze hydrogels,inorganic salts are introduced to prepare hydrogel electrolytes with a wide temperature range.A series of PK（PAM-KGM）hydrogel electrolytes were synthesized by thermal polymerization of acrylamide（AM）and konjac gum Amorphophallus Konjac（KGM）.It is determined that the Li Cl electrolyte with a concentration of 5 M has the best electrochemical performance when the immersion time is 12 h.When the current density is 0.5 A g^-1,the obtained capacity is 189 F g^-1.When the current density is 1 A g^-1,and when the temperature is-30 ^oC,the capacity is still maintained at 106 F g^-1.In this system,a hydrogel electrolyte with good stability and frost resistance was successfully designed and synthesized by soaking in the inorganic salt solution.