Fabrication And Electrochemical Properties Of Electrode Materials For High-Performance Aqueous Zinc-Ion Batteries

It is extensively acknowledged that the development of advanced electrochemical energy storage devices is one of the most significant avenues to cope with the ever-increasingly severe energy crisis.The rechargeable aqueous zinc-ion battery is considered as one of the most promising systems for the next generation of energy storage devices due to several merits,such as high theoretical energy density,good safety,high availability,low cost,and so forth.However,its overall performance tends to be compromised and undermined by the strong electrostatic interaction between Zn²⁺and host and the proton/Zn²⁺co-intercalation in aqueous media.Therefore,the exploiting of a zinc-ion battery with high capacity and a long lifetime remains an uphill and tough task.Based on that,the main research in this thesis is summarized as follows:（1）A novel rational electrode-electrolyte design is achieved with a ZIF/Zn heterostructure as the electrode featuring a microporous host matrix and an organic zinc trifluoromethanesulfonate as the constituent of the electrolyte.A zinc-ion battery based on the ZIF/Zn heterostructure anode delivers a specific capacity of 149 m Ah·g^-1 and maintains as high as 80%electricity capacity after 330 cycles at 1 A·g^-1.The synergistic effect of ZIF of microporous structure and hydrophobic trifluoromethanesulfonate anions establishes a unique electrode-electrolyte interface,which greatly suppresses the formation of dendrites and self-discharge of the Zn anode,endowing the aqueous zinc-ion batteries with the long cycling stability.（2）Boron（B）-doped Fe-N-C active sites confined in hierarchical porous carbon sheets（Fe-BCN）were synthesized using soft-template self-assembly pyrolysis.Notably,the B element introduction can provide an electron-deficient site that can activate electron transfer around the Fe-N-C sites and simultaneously enhance the interaction with oxygen-containing species,thereby accelerating the reaction of the four-electron ORR.The results reveal that the as-prepared Fe-BCN exhibited marvelous ORR performance with a half-wave potential(E_1/2)of 768 m V,a limiting current density of about5.66 m A·cm^-2,and high durability（almost no obvious decay after 5000 cycles）.Moreover,the rechargeable Zn-air battery device assembled by this Fe-BCN catalyst also shows superior performance at a peak power density reaching to～141.4 m W·cm^-2,much higher than that of the Pt/C catalyst(96.3 m W·cm^-2),and remarkable durability（over 60 cycles of operation）.