【摘要】：在當(dāng)今能源短缺和環(huán)境污染的背景下,開發(fā)一種新型的綠色儲能裝置成為重要的解決之道。超級電容器作為一種介于電池與傳統(tǒng)電容器間的新型能量儲存和轉(zhuǎn)換器件,具有功率密度高、充放電效率高、循環(huán)穩(wěn)定性好、綠色環(huán)保等特點(diǎn),因而被廣泛應(yīng)用于多種領(lǐng)域。然而較低的能量密度成為制約其發(fā)展的重要因素。根據(jù)能量密度公式E=1/2CV2知,可以通過提高電極材料電容量(C)和拓寬工作電壓(V)來實(shí)現(xiàn)能量密度的提高。通過設(shè)計(jì)匹配兩種不同儲能方式的電極組裝成非對稱電容器來提高能量密度成為研究熱點(diǎn)。擁有多種化學(xué)計(jì)量比的硫化鎳價格低廉、來源廣泛、比電容高,在高性能超級電容器方面有良好的應(yīng)用前景。本文以多孔泡沫鎳為基底,成功制備比電容高、能量密度高、循環(huán)穩(wěn)定性好的硫化鎳及其復(fù)合納米材料,并與活性炭(AC)構(gòu)成非對稱電容器。通過相關(guān)測試,表征合成材料的形貌與結(jié)構(gòu)、評估其電化學(xué)性能。主要研究內(nèi)容如下:(1)采用簡單便捷的連續(xù)離子層吸附法(SILAR),常溫下,在泡沫鎳集流體上直接合成了純度較高的片層狀NiS。立體片層結(jié)構(gòu)使得材料比表面積增加,活性材料利用顯著率提高,在三電極測試條件下,NiS表現(xiàn)出良好的贗電容特性,1 A g-1的電流密度下,其比電容高達(dá)1678 F g-1。組裝成非對稱電容器后實(shí)現(xiàn)高能量密度42.3 Wh kg-1,5000次循環(huán)充放電后容量保持率為83.0%。表明合成材料具有良好的電化學(xué)性能和循環(huán)穩(wěn)定性。與以往SILAR法得到無定型薄膜相比,該法一步制備金屬硫化物片層具有一定創(chuàng)新性。(2)通過兩步合成法實(shí)現(xiàn)具有核殼結(jié)構(gòu)Co_3O_4@Ni_3S_2三維納米線陣列的構(gòu)建,以多孔泡沫鎳為基底,水熱法合成Co_3O_4納米線以及電沉積法合成Ni_3S_2超薄納米片,共同組成有序的分級結(jié)構(gòu)納米復(fù)合材料。與單一的Co_3O_4和Ni_3S_2電極材料相比,該復(fù)合材料表現(xiàn)出更加優(yōu)異的電化學(xué)性能。在三電極體系中,1 A g-1的電流密度下,其比電容高達(dá)1710 F g-1,循環(huán)充放電1000次后容量保持率為88.5%。組裝成非對稱電容器后,在1 A g-1的電流密度下展現(xiàn)出126.6 F g-1的高比電容和44.9 Wh kg-1的高能量密度。本課題核殼納米線陣列的設(shè)計(jì)可有效縮短離子擴(kuò)散和電子傳輸途徑,通過復(fù)合材料的協(xié)同作用,從而顯著提高性能。(3)通過兩步合成路線制備具有三維分級結(jié)構(gòu)的CoAl-LDH@Ni_3S_2納米片陣列。利用水熱合法在泡沫鎳基底上垂直生長鈷鋁層狀雙氫氧化物(CoAl-LDH)納米片陣列。通過控制電沉積條件,在CoAl-LDH片層表面包裹Ni_3S_2超薄納米片。本課題新穎的形貌設(shè)計(jì)使得合成的復(fù)合材料具有優(yōu)良的電化學(xué)性能。在三電極體系中,1 A g-1的電流密度下,比電容高達(dá)1904 F g-1。以CoAl-LDH為正極,活性炭為負(fù)極,組裝成非對稱電容器,工作電壓可拓寬至1.6 V,5000次循環(huán)充放電后容量保持率仍有84.2%。研究表明,形成的特殊“片-網(wǎng)”結(jié)構(gòu)可顯著增加電極材料與電解質(zhì)溶液離子的接觸機(jī)率,維持機(jī)械穩(wěn)定性從而實(shí)現(xiàn)儲能性能的增強(qiáng)。
[Abstract]:Under the background of energy shortage and environmental pollution, developing a new type of green energy storage device becomes an important solution. As a new type of energy storage and conversion device between battery and traditional capacitor, supercapacitor has the characteristics of high power density, high charging and discharging efficiency, good cycle stability and green environmental protection. However, low energy density has become an important factor restricting its development. According to the energy density formula E=1/2CV2, the increase of energy density can be achieved by increasing the capacitance of electrode material (C) and broadening the working voltage (V). Nickel sulfide with various stoichiometric ratios has low price, wide source, high specific capacitance and good application prospect in high performance supercapacitors. In this paper, nickel sulfide with high specific capacitance, high energy density and good cycle stability was successfully prepared on porous nickel foam substrate. The main research contents are as follows: (1) A simple and convenient continuous ion layer adsorption (SILAR) method was used to synthesize lamellar N with high purity on nickel foam collector at room temperature. IS. Three-dimensional lamellar structure makes the specific surface area of the material increase and the utilization rate of the active material increase significantly. Under the condition of three-electrode test, NiS exhibits good pseudo-capacitance characteristics. At the current density of 1 A g-1, the specific capacitance of NiS is as high as 1678 F g-1. The mass retention rate is 83.0%. The results show that the synthesized materials have good electrochemical properties and cyclic stability. Compared with the amorphous films prepared by SILAR method, the one-step preparation of metal sulfide lamellae is innovative. (2) The core-shell structure of Co_3O_4@Ni_3S_2 three-dimensional nanowire arrays was fabricated by two-step synthesis method, and the porous films were obtained. Co_3O_4 nanowires were synthesized by hydrothermal method and Ni_3S_2 ultrathin nanosheets were synthesized by electrodeposition. The ordered hierarchical nanocomposites were prepared by hydrothermal method and electrodeposition. Compared with single Co_3O_4 and Ni_3S_2 electrode materials, the composites exhibited more excellent electrochemical properties. The specific capacitance is as high as 1710 F g-1, and the capacity retention rate is 88.5% after 1000 cycles of charging and discharging. The asymmetric capacitors exhibit high specific capacitance of 126.6 F g-1 and high energy density of 44.9 Wh kg-1 at the current density of 1 Ag-1. The design of core-shell nanowire arrays can effectively shorten the ion diffusion and electron transmission paths. (3) CoAl-LDH@Ni_3S_2 nanosheet arrays with three-dimensional hierarchical structure were fabricated by a two-step synthesis route. The cobalt-aluminum layered double hydroxide (CoAl-LDH) nanosheet arrays were grown vertically on nickel foam substrates by hydrothermal method. In the three-electrode system, at the current density of 1 A g-1, the specific capacitance is as high as 1904 F g-1. The asymmetric capacitor is assembled with CoAl-LDH as the positive electrode and activated carbon as the negative electrode. The working voltage can be extended to 1.6 V, 5000. The results show that the special "sheet-net" structure can significantly increase the contact probability between electrode materials and electrolyte solution ions, maintain the mechanical stability and enhance the energy storage performance.
【學(xué)位授予單位】：華僑大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2016
【分類號】：TB33;TM53
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本文編號：2192602