Preparation Of Organic/Inorganic Two-Dimensional Materials As Cathode For Novel Secondary Battery

To lessen our dependence on traditional fossil fuels,the global energy structure is undergoing a rapid transformation.High energy density lithium-ion batteries（LIBs）are playing a pivotal role in the development of new energy batteries,but their high costs and safety concerns have limited their widespread adoption in large-scale energy storage markets.To meet the requirements of grid-level energy storage,the development of new ion battery systems with low costs,long cycle life,high power and energy efficiency holds significant strategic importance.Alkaline metal ion batteries and multivalent metal ion batteries share similar energy storage mechanisms with LIBs,but their charge carrier properties differ significantly.Large-sized alkali metal ions or high charge-density multivalent ions can cause irreversible damage to the structures of electrode materials,leading to a decline in battery performance.In recent years,the spotlight has turned towards two-dimensional（2D）materials for energy storage and conversion due to their distinctive physical and chemical properties as well as structural advantages.Along this line,this thesis investigated the electrochemical performance of several 2D cathode materials synthesized through simple liquid-phase methods.The focus is on high-safety,low-cost aqueous zinc-ion batteries and alkali metal-ion batteries.This thesis contains three works described as follows:（1）In order to mitigate the structural damage to the cathode material during Zn²⁺storage,we synthesized a 2D layered vanadium hydrous oxide(H₆V₄O₁₀ haggite phase)under solvothermal reaction conditions as the cathode material for aqueous zinc-ion batteries.Compared to the traditional layered V₂O₅,the uniform stacking structure of H₆V₄O₁₀ was conducive to the storage of zinc ions.Moreover,the open hollow nanosphere morphology of H₆V₄O₁₀ contributed to its excellent electrochemical performance as an electrode material.H₆V₄O₁₀ exhibited a similar specific capacity and initial activation phenomenon to V₂O₅ nanowires in aqueous ZIBs,but it showed superior stability in subsequent cycle tests,further confirming the structural superiority of H₆V₄O₁₀.Remarkably,even at an extremely high current density of 10 A g^-1,H₆V₄O₁₀could still maintain stable cycling for 1000 cycles with a specific capacity of 185 m Ah g^-1,fully exploiting its potential as a cathode material in aqueous ZIBs.（2）In order to store large alkali metal ions efficiently,we employed organic polymer materials with flexible frameworks as the cathode material.1,2,4,5-tetraaminobenzene tetrahydrochloride（TAB·4HCl）and 1,4,5,8-naphthalenetetracarboxylic dianhydride（NTCDA）were used as monomers,and their polymerization was carried out via a solvothermal method.This solvothermal polymerization resulted in a 2D cross-linked polyimide positive electrode material（PI-TAB）.The 2D cross-linked structure of PI-TAB significantly improved the chemical stability and greatly reduced its solubility in the electrolyte.Moreover,the open structure of PI-TAB,composed of stacked nanosheets,promoted ion transport performance.These stable two-dimensional cross-linked structures and open morphology of PI-TAB contributed to its excellent electrochemical performance in alkali metal ion batteries.When PI-TAB was used as the cathode material for sodium-ion batteries,it exhibited outstanding electrochemical properties,retaining a high specific capacity of up to 101 m Ah g^-1 after 6000 stable cycles at 2 A g^-1.Notably,the superior electrochemical performance of PI-TAB was not limited to alkali metal ion batteries;it also demonstrated a remarkable performance in magnesium-ion batteries and aqueous zinc-ion batteries.（3）In order to develop highly versatile electrode materials applicable to various battery systems,we synthesized a series of layered hexaazatriphenylene（HAT）class conjugated polymers and their derivatives through a liquid-phase condensation reaction.These materials were utilized as the cathodes for both alkali metal ion batteries and multivalent ion batteries.HAT molecules possessed electron-deficient properties,rigid conjugated planar structures and abundant imine-active functional groups,endowing them with high theoretical capacity and the potential for efficient storage of various charge carriers.We selected aqueous zinc-ion batteries and sodium-ion batteries as the research systems to evaluate their electrochemical performance.The results showed that the HAT molecules exhibited a high specific capacity(435 m Ah g^-1 in ZIBs).Furthermore,different grafting functional groups exerted significant effects on the discharge voltage,discharge capacity,and cycling stability.We further synthesized a hydrogen-bonded organic framework（HOF）material based on the HAT molecules,exploring its structure and electrochemical properties.The periodic ordered structure of the HOF material provides novel insights for the design and synthesis of related materials.