| The rapid development of current society brings many conveniences,but at the same time,it causes more environmental pollution and energy shortage problems.It becomes a concerned topic around the world that how to develop the secondary energy.In this environment,lithium ion battery develops rapidly within the rechargeable battery industry,and has been used in many fields widely such as the digital products,transportation and so on.With many advantage like high energy density,high output voltage,wide working temperature,no memory effect,and environment friendly,it can be expected that lithium ion battery must have a good prospect in the future.As an important part of lithium ion battery,electrolyte membrane got a lot of attention.In current commercial applications,microporous membrane,represented by Celgard,has good ionic conductivity after soaking liquid electrolyte.And all solid polymer electrolyte has not been commercialized because of the disadvantage of low room temperature conductivity.However,solid electrolyte does not exist the hidden danger and environmental pollution caused by electrolyte volatile.And with the higher mechanical properties and thermal stability,all solid polymer electrolyte is a kind of lithium ion battery membrane which has good development prospect.As a kind of high performance semi crystalline engineering plastics,Poly(aryl ether ketone)(PAEK)has a good thermal stability,chemical stability and excellent mechanical properties.Poly(aryl ether ketone)is often used in proton exchange membrane fuel cell after the sulfonated.However,there is few research in lithium ion battery membrane.We think that functionalizing PAEK by grafting or copolymerization modification methods,has the following foreseeable advantages as lithium ion battery membrane material: strong mechanical performance can not only meet the demand of the strength in the process of battery assembling,but also can remain a certain mechanical strength to withstand the battery when squeeze and collision accident;high thermal stability can maintain stable size and do not decompose under the environment of high temperature.This work aims to design and synthesis novel poly(aryl ether ketone)material.Through grafting,copolymerization functional modification methods,we prepare conducting lithium polymer electrolyte membrane,and carry on the performance tests,explore poly(aryl ether ketone)application prospect in the field of lithium ion battery electrolyte.First of all,we designed and synthesized in a single ion conductor polymer electrolyte.Single ion conductor polymer electrolyte fixes anionic on the polymer molecular chains through covalent bond,and anionic can not migrate due to the large volume.There is only lithium ion in the system can occur migration under the electric field action.In this way,lithium ion migration rate is close to 1 in theory,and can eliminate the influence to lithium ion batteries performance caused by concentration polarization.We hope to functionalize poly(aryl ether ketone),and prepare single ion conducting lithium ion polymer electrolyte.Thus,on the basis that retaining good mechanical performance and thermal stability,explore the method of improving the ionic conductivity.For this,we synthesized a fluorine monomer containing naphthalene ring structure and methoxy: 1,5-bis(4-fluorobenz-oyl)-2,6-dimethoxynaphthalene.Next we synthesized PAEK-OCH3 by nucleophilic polycondensation reaction.Then we prepared SNPAEK with sulfonic acid side chains by demethylation and sulfonic acid lactone grafting reaction,and we controled the ratio of reactants to synthesize a series of SNPAEK-x with different grafting rate.After lithium treated,we got the SNPAEKLi-x containing sulfonic acid lithium alkyl side chain,and characterized the structure of polymer using 1H NMR and FTIR.Polymer electrolyte membrane was obtained by solution casting method,then do the performance testing research.The results showed that ionic conductivity of SNPAEK-Li-x polymer electrolyte increase obviously with the increase of the grafting rate,and the conductivity of SNPAEK-Li-90% was 2.6 x 10-6 S·cm-1 at 30?and reached 1 x 10-5 S·cm-1.At the same time,the mechanical properties and thermal stability of SNPAEK-Li-x was better than other solid polymer electrolyte.Performance study showed that the sulfonic acid lithium side chain poly(aryl ether ketone)material had some advantages as a polymer electrolyte,and the conductivity at room temperature need to further improve.In the second chapter,in order to improve the ionic conductivity of poly aryl ether ketone electrolyte membrane,we bring the low molecular weight PEO chain in the poly aryl ether ketone chain.After the additional electrolyte of lithium salt dissolving in the polymer,coordination effect will be formed between the oxygen and Li+,and under the influence of electric field,Li+ achieves the purpose of conduction by directional movement.In our polymer molecular design,which contains the PEO flexible chain to provide conductive segment,and naphthalene ring structure to provide a good mechanical properties and thermal stability.Thus we consider DMNF containing naphthalene ring structure as double fluorine monomer,methyl hydroquinone as the bisphenol monomer,and copolymerized with chloridized PEO.And by controlling the monomer ratio,different chain segment ratio of “rigid-soft” copolymer is prepared.Then we add lithium perchlorate and prepare solid polymer electrolyte membrane by using the method of solution casting,test the mechanical properties and thermal stability,and study the influence between copolymer ratio and conductivity.The result shows that the different proportions copolymer has the high ion conductivity at high temperature,and with the increase of the PEO chain segment content in the copolymer,the ionic conductivity increases.The ionic conductivity of PAEK-co-PEO-3:1 under 130 ? is 8.9×10-5 S·cm-1.In addition,the polymer electrolyte has good thermal stability and mechanical properties,and with the increase of the PEO ratio,the polymer electrolyte membrane becomes more flexible. |
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