Study On Interface Regulation And Properties Of Tetrapyrrole Materials In Zinc-ion Batteries

Zinc-ion batteries are considered as potential substitutes for lithium-ion batteries because of their low manufacturing cost,abundant resource reserves,high safety and high volume energy density.However,the problems of hydrogen evolution reaction,corrosion,dendrite in aqueous zinc-ion batteries,mass transfer of zinc ions and reaction kinetics in non-aqueous zinc-ion batteries seriously hinder the development of zinc secondary batteries.Based on this,this paper focuses on the key problems of aqueous zinc-ion batteries and"beyond aqueous"zinc-ion batteries respectively,and studies the interface regulation and performance of zinc secondary batteries by using the metal active sites and rich and flexible polar functional groups of tetrapyrrole organometre-metal complexes.The problems of dendrite and hydrogen evolution in aqueous zinc-ion batteries are alleviated by constructing copper phthalocyanine（Cu Pc）intermediate layer and designing gel electrolyte.The addition of specific chlorophyll derivative（Chl）molecules to DMF organic electrolyte promotes the mass transfer of zinc ions and improves the reaction kinetics and the solvation coordination environment of zinc ions.Through these interface control strategies,high performance zinc secondary batteries can be obtained.The main research contents and results are as follows:（1）An 18π-electron macroconjugated system compound called Cu Pc organic intermediate layer is constructed on zinc anode,and the Cu-containing Zn anode is reconstructed in situ by substitution reaction.The synergistic protection strategy of the physical barrier layer and in situ electrochemically formed Cu-Zn mixed layer effectively homogenizes zinc ions flow and promotes interfacial charge transfer.Thus,Cu Pc@Zn exhibits repeated Zn deposition/stripping for over 1200 h at 1 m A cm^-2/1m Ah cm^-2,and obtains a cumulative surface capacity of 1020 m Ah cm^-2 at 10 m A cm^-2/20 m Ah cm^-2（34.2%DOD）.The excellent performance of Cu Pc improves the capacity retention rate of 9,10-anthraquinone（AQ）//Zn batteries by 7.2 times at low current density,and shows the ability to extend the life of metal oxide cathode and high-loading mass organic cathode.（2）Using natural biomaterials such as chitosan（CS）and chlorophyll derivative（Chl）,a novel gel electrolyte with multiple molecular anchors is designed.The gel electrolyte firmly anchors water molecules through ternary hydrogen bonds,effectively reducing the activity of water molecules and inhibiting hydrogen evolution.At the same time,the multiple polar charged functional groups promote the gradient induction and redistribution of Zn²⁺,resulting in directional deposition of Zn²⁺on the Zn（002）surface,and thus achieving uniform deposition of Zn and dendrite-free anode.Therefore,Zn||Zn symmetric battery with the gel electrolyte obtains repeated stripping/electroplating process for more than 1700 h,and the coulombic efficiency of the Zn||Cu battery is as high as 99.4%.In addition,the matched Zn||V₂O₅ full batteries achieve a capacity retention of 81.7%after 600 cycles at 0.5 A g^-1 and a long-term cycle stability of up to1600 cycles at 2 A g^-1.（3）A chlorophyll molecule（Chl）with special conjugated structure and multiple charged functional groups is synthesized as a multifunctional electrolyte additive for non-aqueous zinc ion batteries.Combined with the experimental results and first-principles calculations,it is found that the highly conjugated Chl with different polar functional groups has multi-site zincophilic properties,which can significantly reduce the nucleation barrier,increase the nucleation site,and induce uniform nucleation of metal zinc.Compared with DMF solvent molecules,Chl has lower LUMO level which makes it easier to reduce and decompose to form a SEI layer on the anode surface.In addition,the Chl additive can effectively inhibit the excessive decomposition of the electrolyte,broaden the electrochemical window,and improve the stability of the battery under high pressure.As a result,the electrolyte can achieve repeated Zn stripping/plating for up to 2000 h(cumulative capacity of 2 Ah cm^-2)with an overpotential of only 32 m V and coulomb efficiency of up to 99.4%.The matched PPy@V₂O₅·n H₂O@CC//Zn full battery greatly improves the cycling performance of inorganic cathode materials,and effectively improves the problem of sharp capacity attenuation caused by the electrostatic repulsion between polyvalent Zn²⁺and the main material and the high desolvation energy at the electrode interface.（4）Based on the superior performance of Chl in the organic electrolyte in the previous chapter,a series of chlorophyll derivatives（MChl,M=Ag,Cu,Fe,Ni,Co,Zn,Ga,Mg）containing different central metals（M）is introduced into the DMF organic electrolyte to explore the effect of chlorophyll on the system.The effect of the central metal on the electrolyte system is analyzed in detail by experiments and theoretical calculations.The results show that the Ga Chl additive exhibits a high coulomb efficiency（99.6%）due to the valence electron arrangement and the interaction with solvent molecules.In addition,through the molecular dynamics simulation of electrolytes,it is confirmed that Ga Chl additive can significantly promote the desolvation process of zinc ions,change the solvation environment of zinc ions,and accelerate the mass transfer process of zinc ions in organic electrolytes.As a result,the Zn//polyaniline full battery maintains 80%capacity after 700 cycles at 1 A g^-1.