| Fuel cell is an electrochemical power generation device that directly converts chemical energy into electric energy.Ion exchange membrane is the most important part in the internal structure of fuel cell,which not only ensures the ion transfer in the internal circuit,but also effectively prevents the fuel and oxidant from penetrating into each other inside the cell.At present,there are still many problems in conductivity and stability of ion exchange membrane,which need to be improved.Lithium ion batteries can store the electric energy generated by wind energy and so on to provide driving force for electric vehicles,so as to realize the on-demand or continuous supply of wind energy and other resources.As energy storage secondary batteries,they have also been widely concerned.At present,the electrolyte of commercial lithium-ion battery is still mainly liquid electrolyte,and the resulting electrolyte leakage and other problems limit its development to some extent,so the cost and safety problems have not been well solved.In order to meet the challenge of ion-exchange membrane in fuel cell and lithium ion battery,the design of membrane structure with excellent performance is a key scientific problem.It is mainly composed of polymers,in which the hydrophobic main chain is used to fix the structure,and the branched chain group is used to construct ion transport channels to promote ion transport.Thus,we need not only optimize the membrane structure but also achieve excellent ion conductivity.Therefore,in this study we innovate from the material structure and synthesis method,and design a new type of fast ion conductor(also known as solid electrolyte)with excellent conductivity,which is expected to be applied in batteries,so as to make it more advantageous in fuel cells and lithium ion batteries.The specific research works are as follows:(1)Firstly,synthesizing ammonia propyl functionalized mesoporous silicon sphere matrix proton conductors:the mesoporous materials MCM-41,whose inner wall containing different amounts of propanamide functional groups(5%,10%,15%)were synthesized.With the improvement of amino,the pore diameter and volume decreased gradually.Then,this work has successfully introduced 1H-1,2,4-triazole into mesoporous silica ordered nano-channels through solid evaporation.In the MS-Pr NH2-1 material,which containing 5%propanamide,has a large enough internal space to accommodate more protons.The proton conductivity reaches 8.3×10-3S cm-1,overcoming the heavy dependence of existing commercial sulfonated membranes on water,which is higher than other proton conductivity reported.(2)In the aspect of substrate material improvement,studying the performance of new microporous poly(benzimidazole)matrix proton conductors:a novel microporous polymer(TP-DADMB)was synthesized by monomer copolymerization,and with imidazole loadings of40%(Im@TP-DADMB(40%)),60%(Im@Tp-DADMB(60%)),and100%(Im@Tp-DADMB(100%))as proton conductor materials were prepared by solvent thermal synthesis method.In addition,when imidazole is fully loaded,the conductivity of the material is 1.1×10-5S cm-1at room temperature.The highest conductivity is 2.4×10-3S cm-1at130?,and the activation energy is 0.16 e V.This material has successfully improved the problem of high-temperature ion transport faced by proton exchange membrane,and novel COF material has been selected as the substrate material to enhance the innovation.(3)A cationic covalent organic framework based anion conductor substituted by imidazole at C2 position was synthesized and studied:a series of novel covalent organic framworks(TP-DMDBBI,TP-EMDBBI,TP-PMDBBI)modified by imidazole(C2-position different functional groups)were synthesized,which were then ionized to form cationic skeleton and covalently bonded with anions to finally synthesize anion conductor(TP-PMDBBI-OH).The material achieved excellent conductivity with anion conductivity of 1.78×10-1S cm-1at 80?.The high basic stability and ionic conductivity of the material provide a feasible way for the synthesis and practical application of anion exchange membrane.(4)Synthesizing covalent organic skeleton based lithium ion conductor introduced by plastic crystal:the porous covalent organic framwork material was synthesised by using organic small molecule monomer copolymerization in a solvent thermal condition.And we proposed a simple and universal method,introduced the pyrrole alkyl ion plastic crystal into ordered pore to prepare compound plastic crystal all solid state lithium ion electrolyte.The interactions between pyrrolidinium cation and lithium ion provided a pathway for transport of lithium ions,which in combination with the aligned 1D ordered channels of COFs results in the highest ion conductivity of 10-2S cm-1at 423 K.This work opens up a new strategy for the development of all solid state electrochemical devices capable of operating at medium to high temperatures. |
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