Study On Quasi-solid-state Lithium-organic Batteries Based On Small-molecule Organic Cathode Materials

Quasi-solid-state lithium-metal organic batteries（QSSLOBs）have advantages of high safety,mechanical flexibility,high ionic conductivity.Organic molecules are great promising active materials for QSSLOBs because of their species abundance,high structural adjustability,low cost,and renewable.However,organic compounds as active materials of QSSLOBs still face the problem of poor compatibility with solid electrolytes.The solid electrolytes are different from the organic electrolytes with flowability,and its interface compatibility with the organic electrode is poor,resulting in increased interface impedance and unsatisfactory electrochemical performance.Based on this,the paper introduces hydroxyl functional groups through molecular engineering based on a series of quinones/nitrogenous organic molecules and studies their interfacial compatibility with PVDF-HFP-based gel polymer electrolyte（GPE-0.8）when used as cathode materials.Due to the influence of compatible hydroxyl groups,the electrode/electrolyte interfacial contact and electrochemical performance of QSSLOBs are further improved.The specific research content is as follows:（1）THQAP/QAP with multiple active sites were synthesized by a simple polymerization between 2,5-dihydroxy-1,4-benzoquinone（DHBQ）with 2,3,5,6-tetraamino-1,4-benzoquinon（TABQ）and 1,2-phenylediamine（OPD）,respectively.The QSSLOBs are composed of PVDF-HFP-based GPE-0.8 and THQAP/QAP cathode materials.THQAP/QAP possesses multi-active sites（C=O and C=N）,thus showing high theoretical capacity.In addition,THQAP shows better electrode/electrolyte interfacial compatibility than QAP due to the introduction of compatible hydroxyl groups,showing better electrochemical performance.THQAP exhibited a high reversible capacity of 240 m Ah g^-1 at 50 m A g^-1 and 160 m Ah g^-1after 100 cycles at 200 m A g^-1.In addition,the theoretical calculations and experimental characterization are used to deeply analyze the co-mechanism of THQAP and PVDF-HFP.（2）A series of phthalocyanine-based materials（Ni Pc-8OCH₃ and Ni Pc-8OH）were synthesized by 4,5-dimethoxyphthalonitrile and nickel chloride（Ni Cl₂）at high temperatures.The Ni Pc-8OH as cathode material exhibits better electrochemical performance in QSSLOBs due to the influence of compatible hydroxyl groups.The Ni Pc-8OH provides up to 275 m Ah g^-1 at 50 m A g^-1 and 133 m Ah g^-1 after 60 cycles at 200 m A g^-1.In addition,Ni Pc-8OH exhibits initial charge capacity of 359.6 m Ah g^–1 and excellent capacity retention in quasi-solid-state lithium-based dual-ion batteries.（3）A series of hexaazatrinaphthalene derivatives（HATNA-6OH and HATNA-6OCH₃）were synthesized by condensation reaction between the cyclohexanehexone and 4,5-dimethoxy-1,2-phenylenediamine,which are served as cathode materials for QSSLOBs.HATNA-6OH with compatible hydroxyl groups shows better electrochemical performance than HATNA-6OCH₃ in GPE-0.8 electrolyte,and HATNA-6OH could achieve reversible specific capacity of 125 m Ah g^-1 at 50 m A g^-1.In addition,GPE-0.8 doped with SN can further improve the electrochemical performance of HATNA-6OH,which can be attributed to the plasticizing effect of SN to improve the transport efficiency of electrons/Li⁺in this system.When the content of SN is 40 wt.%（relative to the mass of PVDF-HFP matrix）,the specific capacity of HATNA-6OH increases to 175.3 m Ah g^-1 at 50 m A g^-1,and excellent cyclic performance and capacity retention are achieved.