本文選題：石墨烯 + 氣凝膠　； 參考：《北京化工大學(xué)》2017年博士論文

【摘要】：石墨烯作為一種典型的二維納米材料,因其高比表面積、優(yōu)異電導(dǎo)率和熱導(dǎo)率、突出力學(xué)性能和化學(xué)穩(wěn)定性等,在能源存儲(chǔ)領(lǐng)域具有廣闊的應(yīng)用前景。以氧化石墨烯(GO)為前驅(qū)體材料,通過化學(xué)還原來制備石墨烯是一種有較大發(fā)展?jié)摿Φ募夹g(shù)路線,可以實(shí)現(xiàn)石墨烯的宏量制備。然而,這種方法得到的石墨烯片層容易發(fā)生團(tuán)聚,影響了石墨烯性能的充分發(fā)揮,限制了其更為廣泛的應(yīng)用。本論文以GO為前驅(qū)體制備了三維的石墨烯材料,預(yù)先形成三維石墨烯傳導(dǎo)網(wǎng)絡(luò),保證了石墨烯優(yōu)異傳導(dǎo)性能的充分發(fā)揮。主要?jiǎng)?chuàng)新性研究結(jié)果如下:1、泡沫鎳還原氧化石墨烯用作超級(jí)電容器電極材料:針對(duì)目前三維石墨烯構(gòu)筑過程中需要大量還原劑和能源消耗的問題,我們提出了一種簡(jiǎn)便方法制備可直接用作超級(jí)電容器電極材料的三維還原氧化石墨烯/泡沫鎳(RGO/Nifoam)復(fù)合材料。在pH=2的室溫條件下,直接利用泡沫鎳對(duì)GO進(jìn)行還原,無需添加其它化學(xué)還原劑。得到的RGO在泡沫鎳骨架上組裝,制得RGO/Nifoam復(fù)合材料,直接用作超級(jí)電容器電極材料,無需添加高分子粘結(jié)劑,表現(xiàn)出優(yōu)異的電化學(xué)性能。通過調(diào)節(jié)還原時(shí)間可調(diào)控RGO/Ni foam中的RGO含量,達(dá)到調(diào)控復(fù)合電極材料的單位面積比電容的目的。當(dāng)還原時(shí)間從3天提高到15天,在0.5 mA·Cm-2的電流密度下,其面積比電容從26 mF·Cm-2增加到了 136.8 mF·Cm-2。此外,溫度是影響還原速率的重要因素。當(dāng)提高還原溫度至70℃時(shí),反應(yīng)5小時(shí)后得到的5-hour RGO/Ni foam復(fù)合材料比室溫下反應(yīng)15天得到的15-day RGO/Ni foam復(fù)合材料呈現(xiàn)出更為優(yōu)異的電化學(xué)性能。5-hour RGO/Ni foam復(fù)合材料的面積比電容高達(dá)206.7 mF·cm-2,并且兼具優(yōu)異的倍率性能和循環(huán)穩(wěn)定性,充放電循環(huán)10000次,容量保留率高達(dá)97.4%。在70℃延長(zhǎng)反應(yīng)時(shí)間至9小時(shí),得到的9-hour RGO/Ni foam復(fù)合材料表現(xiàn)出了更高的面積比電容,達(dá)到323 mF·Cm-2,并且仍然兼具突出的倍率性能和優(yōu)異的循環(huán)穩(wěn)定性。2、多級(jí)孔道結(jié)構(gòu)的石墨烯/胞沫鎳復(fù)合材料用作電極材料:成功制備一個(gè)兼具高導(dǎo)電、含大量含氧官能團(tuán)、以及多孔道結(jié)構(gòu)的三維石墨烯復(fù)合材料,并用作高性能超級(jí)電容器電極材料。連續(xù)高效的三維網(wǎng)絡(luò)結(jié)構(gòu)為復(fù)合材料提供了優(yōu)異的倍率性能,而三維網(wǎng)絡(luò)中豐富的含氧官能團(tuán)則為復(fù)合材料提供較高的贗電容。通過將GO/Ni foam復(fù)合材料暴露在打火機(jī)外焰下,幾秒鐘內(nèi)就可得到具有多級(jí)孔道結(jié)構(gòu)的RGO/Ni foam復(fù)合材料。這是因?yàn)榕菽囍械腉O瞬間受熱釋放出大量的氣體導(dǎo)致片層間膨脹與剝離。當(dāng)用作電化學(xué)儲(chǔ)能電極時(shí),這種多級(jí)孔道可以為離子擴(kuò)散和電子傳輸提供快速的通道,而石墨烯片層表面殘留的大量含氧官能團(tuán)可提供大的贗電容。直接用作超級(jí)電容器電極時(shí),RGO/Ni foam復(fù)合材料在0.5和30 A·g-1的電流密度下,其比電容分別高達(dá)407.2和285.5 F·g-1。當(dāng)組裝成兩電極的超級(jí)電容器體系時(shí),其穩(wěn)定電壓窗口高達(dá)1.8 V,可以得到比較可觀的能量密度和功率密度。當(dāng)用作鋰離子電池的負(fù)極材料時(shí),在100 mA·g-1的電流密度下,RGO/Ni foam復(fù)合材料的首圈可逆放電和充電容量分別高達(dá) 2194 和 1372 mA·h·g-1。3、室溫干燥的石墨烯復(fù)合氣凝膠用作高導(dǎo)熱相變儲(chǔ)能復(fù)合材料:為了構(gòu)筑連續(xù)的傳導(dǎo)網(wǎng)絡(luò)和三維骨架,解決相變儲(chǔ)能材料熱導(dǎo)率低和尺寸穩(wěn)定性差的問題,我們制備了可以室溫干燥的三維石墨烯凝膠。GO和高品質(zhì)石墨烯(GNPs)在水中進(jìn)行自組裝,隨后在空氣中室溫干燥,即獲得高導(dǎo)熱和高壓縮性能的高密度石墨烯(RGO/GNP)復(fù)合氣凝膠。RGO片層搭接成一個(gè)三維骨架,而GNPs作為增強(qiáng)相可以避免室溫干燥過程中RGO/GNP水凝膠的體積過度收縮。利用真空浸漬方法將常用的相變儲(chǔ)能材料十八醇填充到多孔的RGO/GNP復(fù)合氣凝膠中,制得具有優(yōu)異導(dǎo)熱性能的十八醇/RGO/GNP(ORG)復(fù)合材料。在12 wt%石墨烯添加量下,ORG復(fù)合材料熱導(dǎo)率高達(dá)～5.92 W·m-1·K-1,相比于純的十八醇提高了 26倍,其相變焓也高達(dá)～202.8 J·g-1。即使在～70 ℃施加1 kg載荷,ORG復(fù)合材料仍然能保持良好尺寸穩(wěn)定性,且未見明顯的十八醇熔體漏流。4、高品質(zhì)的石墨烯氣凝膠用于相變儲(chǔ)能復(fù)合材料:以GO為原料制備的三維石墨烯因其片層上含有殘留的含氧官能團(tuán)和缺陷,嚴(yán)重影響了三維網(wǎng)絡(luò)的傳導(dǎo)性,且這種三維石墨烯材料的尺寸及形狀高度依賴于反應(yīng)器的尺寸和形狀。我們以GO為前軀體,通過低溫濃縮GO水分散液獲得具有優(yōu)秀加工性能的GO組裝物;通過冷凍干燥獲得形狀固定的GO氣凝膠;對(duì)上述GO氣凝膠進(jìn)行高溫石墨化處理,以去除石墨烯片上殘留的含氧官能團(tuán)并修復(fù)缺陷,最終制得兼具高效導(dǎo)熱網(wǎng)絡(luò)和質(zhì)輕特點(diǎn)的高品質(zhì)石墨烯氣凝膠(HGA)。通過簡(jiǎn)單地真空浸漬,即可將熔融的十八醇填充到HGAs的三維網(wǎng)絡(luò)中得到十八醇/HGA (OHGA)相變儲(chǔ)能復(fù)合材料,在較低石墨烯含量下獲得高熱導(dǎo)率。在石墨烯填充量?jī)H僅為～5.0 wt%時(shí),OHGA復(fù)合材料的熱導(dǎo)率高達(dá)～4.28 W·m-1·K-1,比純的十八醇提高了 18倍多;其相變?nèi)廴陟室哺哌_(dá)225.3 J·g-1。
[Abstract]:Graphene is a typical two-dimensional nanomaterial. Because of its high specific surface area, excellent conductivity, thermal conductivity, outstanding mechanical properties and chemical stability, graphene has a broad application prospect in the field of energy storage. Graphene oxide (GO) is a precursor material, and the preparation of graphene by chemical reduction is of great potential. The technical route can be used to make the macro preparation of graphene. However, the graphene lamellae obtained by this method are easy to be reunion, affecting the full play of the properties of graphene and limiting its more extensive application. In this paper, a three-dimensional graphene material was prepared by GO as a precursor, and a three-dimensional graphene conduction network was formed in advance to guarantee the stone. The main innovative research results are as follows: 1, nickel foam is used as a supercapacitor electrode material for the reduction of graphene oxide by nickel foam reduction. In view of the problem that a large number of reducing agents and energy consumption are needed in the construction of three-dimensional graphene, a simple method is proposed to be used directly as a supercapacitor. The three-dimensional reduction of graphene oxide / nickel foam (RGO/Nifoam) composite material in the electrode material. At room temperature of pH=2, the GO is reduced directly with nickel foam, and no other chemical reductants need to be added. The obtained RGO is assembled on the foamed nickel skeleton to produce RGO/Nifoam composites directly as the electrode material of the supercapacitor, without the need to add. The polymer binder shows excellent electrochemical performance. By regulating the reduction time, the RGO content in RGO/Ni foam can be regulated to achieve the purpose of regulating the unit area of the composite electrode material. When the reduction time is increased from 3 days to 15 days, the area is increased to 136.8 from 26 mF Cm-2 under the current density of 0.5 mA. Cm-2. In addition, mF Cm-2., temperature is an important factor affecting the reduction rate. When the reduction temperature is increased to 70, the 5-hour RGO/Ni foam composite obtained after 5 hours reacts more than the room temperature for 15 days, and the 15-day RGO/Ni foam composite presents a more excellent electrochemical performance of the.5-hour RGO/Ni foam composite material. Up to 206.7 mF. Cm-2, with excellent multiplication and cycle stability, charge discharge cycle 10000 times, the capacity retention rate is up to 97.4%. at 70 C to 9 hours. The obtained 9-hour RGO/Ni foam composite shows a higher area specific capacitance, up to 323 mF. Cm-2, and still has outstanding multiplier performance and performance. Excellent cyclic stability.2, multistage channel structure of graphene / foam nickel composite material used as electrode material: a successful preparation of a high conductivity, a large number of oxygen functional groups, and porous structure of the three-dimensional graphene composite material, and used as a high-performance supercapacitor electric pole material. Continuous and efficient three-dimensional network structure composite The material provides excellent multiplier performance, while the rich oxygen functional groups in the three-dimensional network provide high pseudopotential for the composite. By exposing the GO/Ni foam composite to the flame of the lighter, the RGO/Ni foam composite with multistage channel structure can be obtained in a few seconds. This is due to the instant heat of the GO in the foam nickel. The release of a large number of gases leads to interlaminar expansion and stripping. When used as an electrochemical energy storage electrode, this multistage channel can provide a fast channel for ion diffusion and electron transport. A large number of oxygen functional groups remaining on the surface of the graphene layer can provide large pseudo capacitors. The RGO/Ni foam composite is used directly as the electrode of the supercapacitor. Under the current density of 0.5 and 30 A. G-1, when the specific capacitance is up to 407.2 and 285.5 F. G-1. respectively, when the supercapacitor system is assembled into two electrodes, the stable voltage window is up to 1.8 V, and a considerable energy density and power density can be obtained. When used as a anode material for lithium ion batteries, the current density at 100 mA. G-1 The first ring reversible discharge and charge capacity of RGO/Ni foam composites are as high as 2194 and 1372 mA. H. G-1.3. The dry graphene composite aerogel at room temperature is used as a high thermal conductivity phase change energy storage composite material. We have prepared a three-dimensional graphene gel.GO and high quality graphene (GNPs), which can be dry at room temperature, and then dry in the air at room temperature. The high density and high density graphene (RGO/GNP) composite aerogel.RGO lamellae of high thermal conductivity and high compressibility are lap into a three-dimensional skeleton, and GNPs can be avoided as an enhanced phase. The volume of RGO/GNP hydrogel is overcontracted during the process of warm drying. Using the vacuum impregnation method, the commonly used phase change energy storage material eighteen alcohol is filled into the porous RGO/GNP composite aerogel. The excellent thermal conductivity of the eighteen alcohol /RGO/GNP (ORG) composite is prepared. The thermal conductivity of the ORG composite is up to 5.92 under the addition of 12 wt% graphene. W. M-1. K-1 is 26 times higher than pure eighteen alcohol, and its phase transition enthalpy is up to 202.8 J. G-1., even at 1 kg loading at 70 C, ORG composites still maintain good dimensional stability, and no obvious eighteen alcohol melt leakage.4 is found. High quality graphene gas condensate is used in phase change energy storage composite material: GO as raw material The three dimensional graphene, which contains residual oxygen functional groups and defects, seriously affects the conductivity of the three-dimensional network, and the size and shape of this three-dimensional graphene material depends highly on the size and shape of the reactor. We use GO as a precursor to obtain excellent processability GO by condensing GO water solution at low temperature. The GO aerogels are obtained by freeze-drying. The above GO aerogels are graphitized at high temperature to remove the residual oxygen functional groups on the graphene sheets and repair the defects. Finally, high quality graphene aerogels (HGA), which have high thermal conductivity network and light quality, can be obtained by simple vacuum impregnation. Eighteen alcohol OHGA (OHGA) phase change energy storage composite was obtained by filling the fused eighteen alcohol into the three-dimensional network of HGAs. The high thermal conductivity was obtained under the lower graphene content. The thermal conductivity of OHGA composites reached to 4.28 W. M-1. K-1 when the filling amount of graphene was only 5 wt%, and the enthalpy of the phase change melting enthalpy was more than that of the pure eighteen alcohol. Also up to 225.3 J. G-1.
【學(xué)位授予單位】：北京化工大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2017
【分類號(hào)】：TB332;TQ127.11

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相關(guān)期刊論文 前1條

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本文編號(hào)：2027087