本文選題：燃料電池　切入點：復(fù)合膜　出處：《東北師范大學》2017年博士論文　論文類型：學位論文

【摘要】：燃料電池是一種高效、環(huán)保的新型能源轉(zhuǎn)化裝置,能夠?qū)⒒瘜W能直接轉(zhuǎn)化為電能且不受熱機卡諾循環(huán)機理的限制,相比傳統(tǒng)化石能源的使用具有更高的能源利用率。聚合物電解質(zhì)膜作為燃料電池的核心部件,能夠起到阻隔燃料、負載催化劑以及傳導(dǎo)離子的作用,因此其性能的好壞直接決定了燃料電池的使用效果。通常按照所傳導(dǎo)離子的種類將聚合物電解質(zhì)膜分為質(zhì)子交換膜(PEMs)和堿性陰離子交換膜(AEMs),其中PEMs由于其組成電池具有功率密度高、響應(yīng)速度快等優(yōu)點,因此在近幾年的發(fā)展較為迅速。美國杜邦公司生產(chǎn)的全氟磺酸膜(Nafion)作為商業(yè)化的質(zhì)子交換膜產(chǎn)品,具有較高的電導(dǎo)率和化學穩(wěn)定性,但其離子傳導(dǎo)性能嚴重依賴膜的吸水率,在高溫、低濕環(huán)境下性能較差且造價昂貴,因此需要進一步改進。基于以上問題,近期人們開始關(guān)注并開發(fā)AEMs,由于其具有電極氧化還原反應(yīng)速率高、低燃料滲透以及避免使用貴金屬催化劑等優(yōu)勢,因此相對PEMs具有更大的發(fā)展?jié)摿Α５獳EMs所傳遞離子的擴散系數(shù)普遍低于質(zhì)子,導(dǎo)致了AEMs的離子傳導(dǎo)率較低,目前很少有綜合性能超過Nafion膜的陰離子交換膜產(chǎn)品。此外,AEMs中的季銨鹽基團在堿性環(huán)境下容易發(fā)生降解從而影響使用性能,因此對AEMs進行改性研究并彌補上述缺點具有重要的科學意義。在本論文的研究工作中,選擇以聚醚砜類聚合物材料作為AEMs的基質(zhì),分別利用不同的方法對AEMs進行改性,力求使改性陰離子交換膜具有較高的離子傳導(dǎo)能力和良好的化學穩(wěn)定性。具體的工作主要分為以下四個部分:1.合成了含芴結(jié)構(gòu)的聚醚砜類聚合物基質(zhì)(PFSU),通過使用NBS溴代、季銨鹽化等方法對其聚合物側(cè)鏈進行改性,從而得到了含有疊氮基團的季銨鹽化聚醚砜(AMPFSU)。其次,以設(shè)計合成的不同結(jié)構(gòu)和長度的雙官能度炔烴為交聯(lián)劑,通過點擊化學反應(yīng)對AMPFSU膜進行交聯(lián)改性得到一系列交聯(lián)型陰離子交換膜。結(jié)果證明,交聯(lián)能夠促進聚合物膜內(nèi)部緊密堆積從而改善膜的機械性質(zhì),隨著交聯(lián)劑極性的增加,交聯(lián)膜的吸水率與溶脹率等性質(zhì)都會得到提高;AEMs的阻醇性和化學穩(wěn)定性同時隨交聯(lián)而得到增強;對于離子傳導(dǎo)率而言,多數(shù)交聯(lián)膜的電導(dǎo)率相比交聯(lián)前有很大的降低,但d-CPFSU-1膜由于內(nèi)部形成了均勻的納米微相分離結(jié)構(gòu),因此其在80oC的OH-電導(dǎo)率反而提高到193.95mS cm-1,說明交聯(lián)劑的結(jié)構(gòu)對AEMs的微觀相區(qū)結(jié)構(gòu)和性能具有重要影響。2.利用Hummers法合成了氧化石墨烯(GO),并通過水熱還原反應(yīng)等方法對GO進行表面改性,利用可逆加成斷裂鏈轉(zhuǎn)移活性自由基聚合(RAFT)法將芐基氯苯乙烯單體接枝聚合在還原石墨烯上,從而得到了聚合物刷修飾的還原石墨烯(QPbGs)。將不同含量的QPbGs以直接共混的方式引入到氯甲基化聚醚砜(CMPSU)中,所得到的聚合物膜經(jīng)過季銨鹽化和陰離子置換等步驟最終制得了一系列改性復(fù)合陰離子交換膜。研究結(jié)果發(fā)現(xiàn)QPbGs的引入不但可以提高復(fù)合膜的IEC值、吸水率、溶脹率、阻醇性以及機械強度等性質(zhì),在改變膜的內(nèi)部微觀相結(jié)構(gòu)的同時還能夠改善復(fù)合膜的離子傳導(dǎo)性能,其在80oC下的OH-電導(dǎo)率最高可達到91.6m S cm-1。當QPbGs引入過量時,會伴隨著無機摻雜相的團聚效應(yīng),結(jié)果降低了復(fù)合膜的機械性質(zhì)與離子傳導(dǎo)率。3.合成了側(cè)鏈含有疊氮基團的季銨鹽化聚醚砜(AMPSU)和還原石墨烯(rGO),然后將二者直接共混制備出一系列交聯(lián)型復(fù)合陰離子交換膜,在不額外使用交聯(lián)劑和犧牲離子傳導(dǎo)基團的情況下,通過直接加熱的方法使聚合物通過側(cè)鏈上疊氮基團和rGO結(jié)構(gòu)中的不飽和雙鍵之間進行氮烯加成反應(yīng)從而構(gòu)筑交聯(lián)網(wǎng)絡(luò)結(jié)構(gòu)。結(jié)果發(fā)現(xiàn)膜的性質(zhì)如吸水率、溶脹率都隨交聯(lián)而顯著降低,從而導(dǎo)致了膜的離子電導(dǎo)率下降。然而發(fā)現(xiàn)當只有少量rGO(0.5wt%)被摻雜到膜中引發(fā)交聯(lián)便可以使所得交聯(lián)膜的甲醇滲透率降低兩個數(shù)量級,同時增強膜的機械強度和熱穩(wěn)定性。此外,交聯(lián)膜在芬頓試劑中能夠保持穩(wěn)定存在,在60oC 1 M KOH溶液中能夠保持穩(wěn)定500小時。因此,我們制備的交聯(lián)型rGO復(fù)合膜在陰離子交換膜燃料電池中具有很大的發(fā)展?jié)摿Α?.通過無水檸檬酸和乙二胺的水熱反應(yīng)制備出表面具有胺基官能團的碳點(CDs),再利用氯化縮水甘油基三甲基銨(GDTMAC)對其表面進行功能化從而得到季銨鹽化的碳點(QCDs)。最后將不同含量的QCDs引入到咪唑化聚醚砜基質(zhì)(Im-PSU)中制備了一系列新型復(fù)合陰離子交換膜。初步的研究結(jié)果表明:所制備的QCDs具有小尺寸的納米結(jié)構(gòu)(3-4 nm),將其添加到咪唑化聚醚砜基質(zhì)中能夠有效地提高復(fù)合膜的IEC、吸水率、溶脹率、OH-電導(dǎo)率以及氧化穩(wěn)定性。進一步的研究工作仍在進行中。
[Abstract]:Fuel cell is a highly efficient, environmentally friendly new energy conversion device, can convert chemical energy directly into electrical energy and is not affected by the mechanism of the Kano cycle limit, compared with the traditional fossil energy has higher energy efficiency. As a core component of polymer electrolyte membrane fuel cell, to obstruct fuel load effect of catalyst and ion conductivity, so its performance directly determines the quality of the fuel cell performance. Usually according to the kind ion conductive polymer electrolyte membrane will be divided into the proton exchange membrane (PEMs) and alkali anion exchange membrane (AEMs), which PEMs because of its battery with high power density, high response speed fast, so in recent years the development of more quickly. The perfluoro sulfonic acid membrane America produced by DuPont Co (Nafion) as the commercialization of the proton exchange membrane products with high conductivity The rate of water absorption and chemical stability, but its performance is heavily dependent on membrane ionic conduction rate in high temperature, low humidity environment of poor performance and high cost, so it needs further improvement. Based on the above problems, recently people began to pay attention to and the development of AEMs, because of its electrode redox reaction rate is high, low permeability and avoid the use of expensive fuel metal catalyst and other advantages, so PEMs has greater development potential. The diffusion coefficient of AEMs ion transfer but is generally lower than the proton, lead ion conduction AEMs rate is low, there is little comprehensive performance than Nafion membrane anion exchange membrane products. In addition, quaternary ammonium groups in AEMs easily in the alkaline environment the degradation of thus affecting the performance, so the modification of AEMs research and has important scientific significance to make up for the disadvantages. In this paper, choose from polyether Sulfone polymer material as the substrate of AEMs, respectively, using different methods to modify AEMs, ionic conductivity makes the modified anion exchange membrane has high and good chemical stability. The specific work is divided into the following four parts: 1. synthesis of polyether sulfone polymer matrix containing fluorene structure (PFSU), through the use of NBS bromide, the modification of polymer side chain quaternary ammonium salt method, obtained containing azide group of quaternary ammonium salt of polyethersulfone (AMPFSU). Secondly, two different structure and length of officer in the synthesis to alkynes as crosslinking agent for AMPFSU film crosslinking modification to obtain a series of cross-linked anion exchange membrane by click chemistry. The results prove that the crosslinked polymer membrane can promote internal close packing so as to improve the mechanical properties of the film, with the increase of the polarity of the crosslinking agent, water absorbent crosslinked membrane The rate and swelling properties will be improved; AEMs alcohol resistance and chemical stability as the crosslinking is enhanced; the ionic conductivity, conductivity of most crosslinked films compared before the crosslinking has been greatly reduced, but the d-CPFSU-1 film due to internal formation of nano uniform micro phase separation structure, so the 80oC OH- 193.95mS cm-1 to improve the conductivity but, illustrate the structure and performance of micro structure of crosslinking agent on AEMs phase plays an important role in.2. by the method of Hummers graphene oxide (GO) was synthesized by hydrothermal reduction reaction, and methods of surface modification of GO, addition fragmentation chain transfer radical polymerization the use of reversible (RAFT) method of polymerization of ethylene monomer grafted benzyl chlorobenzene in the reduction of graphene, resulting in reduced graphene modified polymer brushes (QPbGs). The different contents of QPbGs were mixed by direct approach The chloromethylation of polyethersulfone (CMPSU), the polymer film obtained by quaternary ammonium salt and the anion exchange step finally made a series of modified composite anion exchange membrane. Results showed that the introduction of QPbGs can not only improve the composite film IEC value, water absorption rate, swelling rate, resistance to alcohol and the mechanical properties such as strength, in the internal change of membrane ionic conductivity of the micro phase structure also can improve the composite membrane, the 80oC under the highest conductivity of the OH- when QPbGs introduced 91.6m S cm-1. excessive, will be accompanied by the agglomeration effect of inorganic doped phase, resulting in reduced side chain containing azide group the synthesis of Quaternary ammonium salt of polyethersulfone membrane mechanical properties and ionic conductivity of.3. (AMPSU) and reduced graphene (rGO), and two were directly prepared by blending a series of crosslinked composite anion exchange membrane, without additional use The crosslinking agent and sacrifice ion conduction group, by directly heating the polymer through the side chain of the azide group and rGO in the structure of unsaturated double bond nitrene addition reaction to construct cross-linked network structure. The results showed that the membrane properties such as water absorption and swelling rate were significantly decreased with increasing of crosslinking, which leads to the ionic conductivity of membrane decreased. However, when only a small amount of rGO (0.5wt%) was doped into membrane cross-linking can make the methanol permeability of the cross-linked membranes decreased by two orders of magnitude, while enhancing the mechanical strength and thermal stability of the film. In addition, the crosslinked films can keep stable in the presence of Fenton reagent. Can keep stable for 500 hours in the 60oC 1 M KOH solution. Therefore, we prepared crosslinked rGO composite membrane preparation membrane fuel cell.4. has great potential for development by anhydrous citric acid on anion exchange The hydrothermal method and ethylenediamine prepared with amine groups on the surface of carbon (CDs), using three methyl ammonium chloride glycidyl (GDTMAC) functionalized on the surface so as to obtain the quaternary ammonium salt of carbon (QCDs). The different content of QCDs into the matrix of imidazole polyether sulfone (Im-PSU) in the preparation of a series of new composite anion exchange membrane. The preliminary results show that the as prepared QCDs nanostructures with a small size (3-4 nm), will be added to the PES of imidazole matrix can effectively improve the composite membrane IEC, water absorption rate, swelling rate, OH- the electrical conductivity and oxidation stability. Further research work is still in progress.

【學位授予單位】：東北師范大學
【學位級別】：博士
【學位授予年份】：2017
【分類號】：TQ425.236;TM911.4

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相關(guān)期刊論文 前4條

1 顧梁;孫哲;徐丹;嚴鋒;;堿性陰離子交換聚合物膜研究進展[J];功能高分子學報;2016年02期

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本文編號：1636288