本文選題：熱剝離石墨烯 + 還原氧化石墨烯��； 參考：《華中科技大學(xué)》2014年碩士論文

【摘要】：鋰二次電池是具有極大潛力和應(yīng)用前景的次世代便攜儲能器件，而以硫作為正極儲能材料的鋰硫電池體系是近年來發(fā)展最為迅速，表現(xiàn)最為優(yōu)秀的體系之一。本文分別分析探索了一種硫-石墨烯復(fù)合正極材料和一種潛力巨大的全固態(tài)鋰硫電池，分析了其性能影響因素。 本實驗利用兩種不同形態(tài)的石墨烯材料與單質(zhì)硫進行復(fù)合，制備了一系列表現(xiàn)優(yōu)良的硫碳復(fù)合材料。通過大量的實驗證明：這種材料在保證了較高硫負載量的同時，表現(xiàn)出了優(yōu)良的電化學(xué)性能，同時也較為有效的克服了鋰硫電池正極材料存在的：導(dǎo)電性差、循環(huán)性能差等缺點，并在一定程度上抑制了穿梭效應(yīng)帶來的負面影響，同時也進一步改善了石墨烯材料存在的負載量和利用率較低的缺陷。 我們利用熱剝離石墨烯這種超薄的二維材料作為基底負載了單質(zhì)硫，在硫單質(zhì)表面形成了一層保護層，這種保護層既能極大的提高其導(dǎo)電性能又能夠有效的防止循環(huán)過程中活性材料的流失。我們進一步在這種片層材料的外層包覆了還原氧化石墨烯（一種具有優(yōu)良導(dǎo)電性能和物理性質(zhì)的薄膜材料），實驗結(jié)果表明，該方法能夠明顯提高單質(zhì)硫的利用率，前50個循環(huán)的電化學(xué)性能全面優(yōu)于未包覆材料。本文中還同時研究了含硫量、包覆量、不同粘結(jié)劑，不同熱剝離石墨烯基底的制備條件等變量對電化學(xué)性能影響。 實驗結(jié)果表明，在不計其他變量影響的前提下，存在一個最佳的包覆量，，以及最佳的含硫量（60%-70%）和最佳的正極片厚度（10-15μm）使電化學(xué)性能達到最佳，而過多的含硫量會造成介孔的堵塞和片層結(jié)構(gòu)的損傷。氧化石墨在1050℃下的剝離程度和孔徑均優(yōu)于1000℃和950℃下剝離的樣品，而在氣氛保護下進行分段式預(yù)熱剝離得到的石墨烯的剝離程度和孔徑優(yōu)于在馬弗爐無氣氛保護下一次剝離得到的石墨烯。 由于電解質(zhì)的選擇對于鋰硫電池性能的影響較大，我們以此正極硫碳復(fù)合材料為基礎(chǔ)設(shè)計了一種全新的全固態(tài)鋰硫電池作為探索和對比。由固態(tài)電解質(zhì)和電極之間的多點接觸問題導(dǎo)致的高接觸電阻一直是困擾全固態(tài)鋰硫電池發(fā)展的因素之一，本體系采用了實驗室制備的LATP陶瓷固態(tài)電解質(zhì)和CPE半固態(tài)電解質(zhì)，以CPE半固態(tài)電解質(zhì)作為緩沖區(qū)，以緩沖層的形式置于電極和電解質(zhì)之間，提高接觸面的電導(dǎo)率，并減少LATP材料和負極Li片接觸時造成電解質(zhì)損失。以球磨BP2000與硫制得的復(fù)合材料為對照組，對比多種正極以及有無緩沖層對固態(tài)電池性能的影響。 試驗結(jié)果表明：在全固態(tài)電池體系中石墨烯-硫復(fù)合材料首次放電比容量不如對照組材料，但其循環(huán)穩(wěn)定性的表現(xiàn)卻優(yōu)于對照組，表現(xiàn)出石墨烯-硫復(fù)合材料較好的循環(huán)穩(wěn)定性。而沒有使用緩沖層的電池的性能表現(xiàn)和使用了緩沖層的電池差距較大，這說明此緩沖層在全固態(tài)電池中起著重要的作用。
[Abstract]:Lithium secondary battery is the next generation portable energy storage device with great potential and application prospect, and the lithium sulfur battery system with sulfur as positive energy storage material is one of the most rapid development and best performance in recent years. In this paper, a sulfide-graphene composite cathode material and an all-solid-state lithium-sulfur battery with great potential are investigated, and the factors affecting the performance of the battery are analyzed. In this experiment, a series of excellent sulfur / carbon composites were prepared by combining two kinds of graphene materials with simple sulfur. Through a large number of experiments, it is proved that this material not only guarantees high sulfur loading, but also exhibits excellent electrochemical performance. At the same time, it also effectively overcomes the existence of cathode materials for lithium sulfur batteries: poor conductivity, The poor cycle performance and so on can restrain the negative effects of the shuttle effect to a certain extent and further improve the defects of the graphene material with low load and low utilization ratio. We use thermal stripping graphene, a thin two-dimensional material, as a substrate to load elemental sulfur and form a protective layer on the surface of sulfur. The protective layer can greatly improve its conductivity and effectively prevent the loss of active materials during cycling. We further coated the outer layer of this lamellar material with reduced graphene (a thin film with excellent conductivity and physical properties). The experimental results show that this method can significantly improve the utilization rate of elemental sulfur. The electrochemical performance of the first 50 cycles is better than that of the uncoated material. At the same time, the effects of sulfur content, coating amount, different binder and different preparation conditions on the electrochemical properties of graphene substrate were also studied. The experimental results show that the optimum coating amount, the optimum sulfur content and the optimum thickness of the cathode sheet (10 ~ 15 渭 m) can achieve the best electrochemical performance without taking into account the influence of other variables. Excessive sulphur content can cause mesoporous blockage and lamellar structure damage. The peeling degree and pore size of graphite oxide at 1050 鈩

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