Research On Aqueous Electrochemical Energy Storage System Based On Zinc Anode

The design and development of new electrochemical energy storage devices have been concerned in the field of energy and energy storage technology.The performance of high energy density,large power output,safety and pollution-free is the eternal goal of the development of energy storage devices.Aqueous Zn-ion energy storage devices have great potential as the representative progressive technology nowdays.However,the scale application of aqueous Zn-ion energy storage devices has not been well solved due to the few kinds of cathode materials that can match Zn anode and the low stability of Zn electrode structure.Therefore,in order to improve the electrochemical performance of Zn-ion energy storage system,this work systematically carries out the research of aqueous electrochemical energy storage system based on Zn anode,along the route of"the design and preparation of cathode materials–the modification and dendrite suppression of Zn anode–performance research".The main work includes:(1)A typical metal-organic molecule ferrocene with fast reversible redox rate was selected and hybridized with activated carbon in different proportions,and the hybrid material was used as the cathode materials of aqueous Zn-ion hybrid supercapacitor.The differences in specific surface area,elemental composition,microscopic morphology and capacitance performance of ferrocene-activated carbon hybrid materials with different ratios were systematically explored.The results show that the ferrocene-activated carbon hybrid material enhances the performance through the synergistic effect of each other,manifesting as having larger specific surface areas,more active sites and better electrochemical performance.Among them,the ferrocene-activated carbon hybrid material with a mass ratio of 1:1 exhibits the best electrochemical performance,including the highest specific capacitance(112.2 F/g at 0.1 A/g),the highest energy density(40Wh/kg),excellent low temperature performance(70 F/g at-30°C),and long-term cycling stability.(2)The organic compound 2,2,6,6-tetramethylpiperidine oxide(Tempo)was selected to be hybridized with activated carbon,and the hybrid materials were used as the cathode materials of aqueous Zn-ion hybrid supercapacitors.The microscopic morphology of the hybrid materials with different proportions were systematically explored.The results show that the Tempo-activated carbon hybrid material with a mass ratio of 1:1 has the best electrochemical performance,including the highest specific capacitance(170.8 F/g at 0.1 A/g),the highest energy density(23.7 Wh/kg)and low charge transfer resistance(190?).(3)An artificial interface layer was prepared on the Zn surface by spin coating to stabilize the Zn anode.The composition and thickness of the artificial interface layer can be effectively controlled by adjusting the type of film-forming solution and the film-forming time.Using Nafion solution,PVB solution and anhydrous ethanol mixed solution with volume ratio of 1:9:400,the Zn electrode with stable performance was successfully prepared by rotating on the Zn surface for 100 s(Nafion-PVB-C₂H₅OH-1-9-400@Zn-100s).Zn-Zn half battery and Zn-Mn O₂ full battery assembled by Nafion-PVB-C₂H₅OH-1-9-400@Zn-100s metal anode were studied.The electrochemical test results show that the overpotential of the modified Zn anode symmetric battery is reduced to 50 m V compared with bare Zn,and it can also be cycled for 650 hours.Furthermore,the Zn-Mn O₂ full cell with modified Zn show a decrease in polarization voltage and polarization current to-1.06 V and-4.17 m A/cm~2.