【摘要】：超級電容器,作為一種新穎、低價、環(huán)保、高性能的儲能系統(tǒng),在資源日益枯竭的今天受到了學(xué)者們的廣泛關(guān)注。石墨烯水凝膠具有團(tuán)聚度小、自支撐性、不用粘合劑、三維交聯(lián)網(wǎng)絡(luò)孔結(jié)構(gòu)等優(yōu)秀的結(jié)構(gòu)特性,并且作為超級電容器電極材料,其循環(huán)壽命好,在較大的電流密度下仍可以保持原有的比電容,但是比電容較低。因此本文研究重點(diǎn)是通過復(fù)合來提高石墨烯水凝膠的比容量和能量密度。通過簡單的水熱法制備了石墨烯/碳納米管復(fù)合水凝膠。石墨烯水凝膠擁的交聯(lián)網(wǎng)絡(luò)結(jié)構(gòu)為電解液的進(jìn)出以及帶電離子的嵌入和脫出提供了通道,同時碳納米管插層在石墨烯片之間還可以減少石墨烯片層的層疊現(xiàn)象,提高材料的電導(dǎo)率,并且增加了復(fù)合物的比電容。所得產(chǎn)物的電容量可以達(dá)到350.1 F/g,并且擁有良好的倍率特性,可以在大電流下使用。同時具有較高的能量密度,可以達(dá)到175.1 Wh/kg。并且具有良好的循環(huán)穩(wěn)定性,在充放電循環(huán)一千圈后仍然可以保持第一圈充放電90%的電容量,非常具有實(shí)際應(yīng)用價值。石墨烯/二氧化釩復(fù)合水凝膠是通過一步水熱法制備得到的。水凝膠三維網(wǎng)絡(luò)結(jié)構(gòu)的存在降低了復(fù)合材料的電阻,同時二氧化釩的存在增加了復(fù)合材料的電容量,減少了石墨烯片的層疊現(xiàn)象。在兩種組分協(xié)同作用下,這種復(fù)合水凝膠具有較大的比容量,其最大電容量可以達(dá)到281.5 F/g,并且循環(huán)穩(wěn)定性良好,在充放電一千圈后,其電容量仍然可以保持第一次充放電電容量的95%。同時,復(fù)合物水凝膠擁有較高的能量密度,可以達(dá)到140.8 Wh/kg,這與傳統(tǒng)電池相比具有很明顯的優(yōu)勢。該復(fù)合物水凝膠適用于超級電容器電極材料。通過水熱法制備了石墨烯水凝膠,然后采用化學(xué)浴(Chemical Bath Deposition, CBD)的方法以石墨烯水凝膠為基底生長了 NiOOH納米片。石墨烯水凝膠的交聯(lián)網(wǎng)絡(luò)結(jié)構(gòu)為電極反應(yīng)提供了更多的活性位點(diǎn);其三維孔結(jié)構(gòu)的存在不僅避免了石墨烯片層的層疊和團(tuán)聚現(xiàn)象,同時為電解液離子的傳輸提供了通道,降低了復(fù)合水凝膠的電阻。NiOOH作為贗電容有較高的比電容,但是由于生長的太少,復(fù)合水凝膠的比電容并沒有太大的提高,僅由61.7 F/g提高到了 91.3 F/g。但是其循環(huán)穩(wěn)定性良好,循環(huán)一千圈后,其電容量仍可以保持初始值的91.5%,有一定的實(shí)際應(yīng)用價值。
[Abstract]:Supercapacitor, as a novel, low-cost, environmentally friendly and high-performance energy storage system, has been paid more and more attention by scholars when the resources are exhausted day by day. Graphene hydrogel has excellent structural characteristics, such as small agglomeration, self-support, no adhesive, three-dimensional crosslinked network pore structure and so on. As an electrode material of supercapacitor, graphene hydrogel has good cycle life and can still maintain the original specific capacitance at high current density, but the specific capacitance is low. Therefore, the focus of this paper is to improve the specific capacity and energy density of graphene hydrogel by recombination. Graphene / carbon nanotube composite hydrogel was prepared by simple hydrothermal method. The crosslinked network structure of graphene hydrogel provides a channel for electrolyte in and out of electrolyte and the embedding and stripping of charged ions. At the same time, carbon nanotube intercalation between graphene sheets can also reduce the stacking phenomenon of graphene lamellae, improve the conductivity of the material, and increase the specific capacitance of the composite. The capacitance of the product can reach 350.1 F / g, and it has good rate characteristics and can be used at high current. At the same time, it has a high energy density, which can reach 175.1 Wh/kg.. It has good cycle stability and can still maintain 90% of the capacitance of the first cycle after a thousand cycles of charge-discharge cycle, which is of great practical application value. Graphene / vanadium dioxide composite hydrogel was prepared by one-step hydrothermal method. The existence of three-dimensional network structure of hydrogel reduces the resistance of the composites, while the existence of vanadium dioxide increases the capacitance of the composites and reduces the stacking phenomenon of graphene sheets. Under the synergistic action of the two components, the composite hydrogel has a large specific capacity, its maximum capacitance can reach 281.5 F 鈮，

本文編號：2506056