Construction Of Aqueous Zinc-ion Batteries Based On Metal-organic Frameworks And Their Applications In Flexible Bioelectronic Device

Flexible bioelectronic devices played an important role in personalized medicine and gained increasing interest in recent years.As a result,it is desperately required to develop corresponding energy-storage systems to power them.Rechargeable aqueous zinc-ion batteries（AZIBs）have attracted wide attention due to their high energy density,low cost,safety,and environmental friendliness,and are considered as one of the most promising flexible energy storage devices.Nevertheless,poor cyclic stability and lack of suitable electrode materials seem to limit the wide application of AZIBs in the energy storage field.There are some shortcomings in the performance stability and security of reported AZIBs cathode materials.Thus,discovering new materials with excellent electrochemical properties and studying the reaction mechanisms are vital for the further development of AZIBs.Metal-organic frameworks（MOFs）as a unique class of porous crystalline materials,have attracted much interest for many applications due to their huge variety of structures,large surface areas and adjustable porosity.In recent years,examples of MOFs as electrode materials for lithium and sodium-ion batteries indicate they have great potential in energy storage field.To sum up,this work aims to improve the electrochemical performance of flexible rechargeable aqueous zinc-ion batteries,carries out a series of research work around the preparation of MOFs cathode material,construction of AZIBs system,energy storage application and reaction mechanism exploration,as well as the application of flexible wearable devices.The main contents are as follows:1.Based on the extensive application of mangan-based electrode materials in AZIBs and the special characteristics of MOFs materials of high porosity and large specific surface area.In this chapter,a Mn-based metal-organic framework（MOF）,MOF-73,is used for the first time to make a novel cathode of AZIBs and further investigate its great capacity enhancement mechanism.The results of material characterization show that the MOF-73 with high crystallinity was successfully synthesized.Electrochemical test results show that MOF-73 can render a voltage plateau of ¹.47 V and induce deposition of manganese ions to form manganese based compounds to co-contribute a high-specific capacity of 875 mA hg^-1(0.84 mA h cm^-2).2.Through the research in the last chapter,we constructed an AZIBs system with MOF-73 as the cathode material.The system showed good electrochemical performance.In this chapter,we chose to use Ca²⁺,which has a larger ionic radius to synthesize a metal-organic framework material.The synthesized material is named Ca-PTA.In addition,the electrochemical behaviors of this MOF are investigated by some ex-suit measurements in detail.The Ca-PTA cathodes deliver a high-specific capacity of 472 mA h g^-1(0.51 mA h cm^-2)at 50 mA g^-1,along with 90% capacity retention(300 mA g^-1)after 2700 cycles and exhibit a discharge platform at ¹.5 V also induce deposition of manganese ion to form manganesebased compounds to co-contribute a high-specific capacity.3.In the above two chapters,the Zn/MOF-73 and Zn/Ca-PTA AZIBs are successfully constructed.We chose the Zn/ Ca-PTA system with higher cycle stability for the assembly of flexible batteries.The results showed that the flexible battery system shows the stable electrochemical performance when the battery is bent and folded to 45°,90° and 180°.The practical application of the flexible battery shows its practicability in bioelectronic equipment.This work provides new fundamental insight into the zinc storage mechanism of MOFs,which can be helpful to guide future efforts exploring new MOFs as competitive cathodes for AZIBs.And promote the technological progress of flexible wearable batteries with high safety.