Synthesis Of MOFs-based Composite Gel-electrolyte And Their Application In Energy Storage

As the rapid development of electric vehicles,the demand for safe and large-scale energy storage systems is getting higher and higher.Therefore,all-solid-state batteries are being intensively studied in the research of new generation power sources.Composite gel electrolytes combining with the characteristic of organic liquid electrolyte and solid electrolyte,not only have higher room temperature ionic conductivity,but also have higher safety performance and better electrochemical performance.This thesis firstly uses metal-organic frameworks(MOFs)as substrate material for gel electrolyte to construct three-dimensional cross-linked network gel composite electrolyte.This thesis contains the effect of various aspects of cathode materials,solvent types,and matrix materials to composite gel electrolyte,and their physical properties,electrolyte characteristics,and battery performance have been analyzed through corresponding characterization and testing methods.The main results of this thesis are as follows:(1)This thesis successfully synthesises ZIF-8 nano-materials with rhombic dodecahedron structure and uniform size by the solution static method.The material has a small particle size(about 50 nm),a large Brunauer-Emmett-Teller surface area of about 1460 m2/g and the innumerous micro-pore structure.The ZIF-8 based composite gel electrolyte has been formed by the film and dipping method.The composite gel electrolyte not only has wide and the stable electrochemical window of 0 V-4.7 V(vs Li+/Li),high lithium ion migration number of 0.667 and excellent room ionic conductivity of 1.05 ×10-4 S/cm,but also has good interfacial stability with lithium metal and inhibits the growth of lithium dendrites.Besides,it also has excellent mechanical properties,thermal stability and safety performance.(2)ZIF-8-based composite gel electrolyte has been assembled into solid lithium battery.It shows excellent specific capacity,rate performance and cycle stability.When the current density is 50 mA/g,the initial discharge capacity is about 135 mAh/g and the capacity retention rate is close to 90%after 100 cycles.When the current density increases to 5 A/g,the discharge capacity can still maintain 65 mAh/g.At the same time,the ZIF-8-based composite gel electrolyte can also be applied to other battery systems such as lithium-oxygen batteries,lithium-sulfur batteries and sodium-ion batteries.However,there are still some problems that need further optimization.In addition,the ZIF-67 nanomaterials also can use in lithium battery and exhibits similar electrochemical properties.