Study On Preparation And Electrochemical Properties Of High Efficiency And Low Cost Sodium And Zinc Ions Battery

In the past few decades,lithium-ion batteries have been the most popular energy storage devices,and they have always played an important role in the entire energy storage field due to their high energy density,long cycle life and no memory effect.However,lithium and cobalt resources are limited and unevenly distributed around the world,so the production cost of lithium-ion batteries will become higher and higher in the future.It is extremely urgent to explore new and efficient energy storage devices in addition to lithium-ion batteries to meet the growing demand for energy storage.The abundant sodium element has electrochemical properties similar to those of lithium.The safe,non-toxic zinc anode has a high volumetric energy density,so sodium ion batteries?SIB?and zinc ion batteries?ZIB?are considered to replace lithium ions.A more suitable alternative to batteries.At the same time,sodium ion batteries also face some problems,such as the volume expansion of the tin dioxide anode during the reaction,resulting in poor cycle stability,and conductivity problems of oxide and sulfide electrode materials.The third chapter of this thesis probes into the existence of SnO₂.A composite anode of nano-SnO₂ and graphene is synthesized by hydrothermal method.The graphene in the composite can improve the conductivity of SnO₂,the nano-sized SnO₂ can alleviate the volume expansion of sodium ion intercalation/deintercalation while shortening the ion diffusion distance and effectively increasing the ion diffusion rate.Further,an electrochemical test was carried out in a sodium dual ion battery system,and at a current density of 200 mA g^-1,the specific capacity was 70 mAh g^-1 when the cycle was 300 cycles,and the capacity retention rate was 72.5%.In addition,zinc ion batteries have obvious potential in the application of large-scale energy storage systems due to their low cost and environmental friendliness.In particular,researchers have recently proposed the concept of zinc ion aqueous hybrid supercapacitors?ZHSs?,revealing the advantages of high safety and high rate performance.However,the capacity and long cycle of the hybrid system have yet to be improved.In the fourth chapter of this thesis,a high specific surface area activated carbon is studied as a cathode electrode material,which effectively improves the capacity and cycle performance of the zinc ion aqueous hybrid supercapacitor.Activated carbon with pitch as a precursor to obtain activated carbon with high specific surface area,used as the cathode electrode of aqueous-based zinc ion hybrid supercapacitor,metal zinc foil as anode electrode,and the aqueous solution of zinc trifluoromethanesulfonate as electrolyte to obtain excellent electrochemical performance:The long cycle test was carried out at a current density of 10A g^-1.After 20,000 cycles,the discharge capacity of the system was still as high as 86 mAh g^-1,and the system could charge the battery up to 19 s.