發(fā)布時間：2018-05-01 18:25

  本文選題：超級電容器 + 納米二氧化錳�。� 參考：《濟(jì)南大學(xué)》2017年碩士論文

【摘要】：超級電容器因具有高功率密度和長期循環(huán)穩(wěn)定性,已經(jīng)成為極具吸引力的電化學(xué)存儲系統(tǒng)之一。由于理論比容量高,成本低,儲量豐富和環(huán)境友好性等特點,氧化錳(MnO_2)受到越來越多的關(guān)注。本文首先采用水熱法制備了δ-MnO_2,α-MnO_2,γ-MnO_2和β-MnO_2四種不同晶體結(jié)構(gòu)的納米MnO_2,探究了反應(yīng)時間和反應(yīng)溫度對納米MnO_2晶體結(jié)構(gòu)和形貌的影響,并且對其進(jìn)行了電化學(xué)性能的測試,結(jié)果表明納米δ-MnO_2的電化學(xué)性能最佳,在此基礎(chǔ)上,通過金屬離子摻雜和導(dǎo)電聚合物復(fù)合兩種方法對δ-MnO_2進(jìn)行了改性。具體研究內(nèi)容及主要結(jié)果如下:1.以KMnO4為原料,在酸性條件下,采用一步水熱法,分別在100°C、140°C、180°C下反應(yīng)1 h、3 h、6 h、12 h,得到了不同形貌的納米δ-MnO_2和α-MnO_2。通過對所得樣品的表征及電化學(xué)性能測試,實驗結(jié)果及分析表明:隨著反應(yīng)溫度的升高和反應(yīng)時間的延長,所得到的MnO_2首先生成片狀的δ-MnO_2,逐漸長成由納米片組成的花球狀δ-MnO_2,最后納米片發(fā)生卷曲為納米管狀的α-MnO_2。在這個過程中MnO_2的晶體結(jié)構(gòu)由2D層狀轉(zhuǎn)變?yōu)閇2×2]的隧道結(jié)構(gòu)。實驗所得樣品的顏色也因為晶體結(jié)構(gòu)的轉(zhuǎn)變由黑色逐漸變?yōu)樯詈稚�。說明反應(yīng)溫度和反應(yīng)時間是影響MnO_2的晶體結(jié)構(gòu)和形貌的重要因素。其中,在反應(yīng)溫度為100℃,反應(yīng)時間為1 h的條件下得到的δ-MnO_2比電容高達(dá)196.8 F g-1。隨著反應(yīng)溫度是的升高和反應(yīng)時間的延長,所得樣品的比電容逐漸減小。γ-MnO_2和β-MnO_2的最高比電容分別為117.2 F g-1和37.6 F g-1。分析比較可得,納米δ-MnO_2的比容量明顯優(yōu)于其它晶型的MnO_2。2.在上述研究基礎(chǔ)上,選擇δ-MnO_2作為金屬離子摻雜的對象,以KMnO4為母鹽,泡沫鎳(Ni Foam,簡稱NF)為載體,通過簡單的水熱法分別合成了Co~(2+),Bi~(3+)和Fe~(3+)離子摻雜的δ-MnO_2/NF復(fù)合物,δ-MnO_2的電化學(xué)性能得到了很大的提高。在2 mV s-1的掃描速率下,摻雜2at.%Co~(2+),2at.%Bi~(3+),4at.%Fe~(3+)得到的δ-MnO_2/NF的比電容分別是506.8 F g-1、365.6 F g-1、376.1 F g-1,遠(yuǎn)高于未摻雜δ-MnO_2/NF的198.5 F g-1;其阻抗性能也得到了很大的改善。3.以苯胺單體為還原劑,以過硫酸銨為氧化劑,在冰浴條件下制備了海參狀納米棒聚苯胺(PANI)。以納米PANI為基底,以KMnO4為氧化劑,采用原位生長法在PANI表面生長納米片狀的δ-MnO_2,得到了納米δ-MnO_2@PANI復(fù)合物。通過對復(fù)合材料的表征和電化學(xué)性能的測試,結(jié)果表明:納米PANI對KMnO4表現(xiàn)出良好的還原性能,使得納米尺度的δ-MnO_2成功負(fù)載在PANI納米棒的表面。納米δ-MnO_2@PANI復(fù)合材料在0.5A g-1的電流密度下,比電容達(dá)到524.2 F g-1,遠(yuǎn)遠(yuǎn)大于單純的PANI和δ-MnO_2的比電容。反過來,以納米MnO_2為基底,在其表面生長PANI,在2 mV s-1的速率下,所得納米PANI@δ-MnO_2復(fù)合物的比電容為261.8 F g-1,氧化錳的電容性能沒有得到明顯改善。
[Abstract]:Supercapacitors have become one of the most attractive electrochemical storage systems due to their high power density and long-term cycle stability. Due to the characteristics of high theoretical capacity, low cost, abundant reserves and environmental friendliness, manganese oxide (MNO _ 2) has attracted more and more attention. In this paper, four kinds of nanocrystals of 未 -MnO _ 2, 偽 -MnO _ 2, 緯 -MnO _ 2 and 尾 -MnO _ 2 were prepared by hydrothermal method. The effects of reaction time and reaction temperature on the structure and morphology of nanocrystalline MnO_2 were investigated, and their electrochemical properties were tested. The results show that 未 -MnO _ 2 has the best electrochemical performance. On the basis of this, 未 -MnO _ 2 is modified by metal ion doping and conducting polymer composite. The specific research contents and main results are as follows: 1. Using KMnO4 as raw material and under acidic conditions, the nanosized 未 -MnO _ 2 and 偽 -MnO _ 2 were obtained by one-step hydrothermal reaction at 100 擄C ~ (10) C ~ (140) C ~ (180 擄C) for 1 h ~ 3 h ~ 6 h ~ (-1) ~ (-1) ~ (-1) ~ (-1) h ~ (-1) ~ 12 h ~ (-1) respectively. Through the characterization and electrochemical performance test of the samples, the experimental results and analysis showed that: with the increase of reaction temperature and the prolongation of reaction time, The obtained MnO_2 first produces a flake 未 -MnO _ 2, and gradually grows into a spherical 未 -MnO _ (2) structure made up of nanochips. Finally, the nanochips are curled into nanotube 偽 -MnO _ (2) _ s _ (2). In this process, the crystal structure of MnO_2 is changed from 2D layer to [2 脳 2] tunnel structure. The color of the sample was changed from black to dark brown. The results show that the reaction temperature and reaction time are important factors affecting the crystal structure and morphology of MnO_2. The specific capacitance of 未 -MnO _ 2 is up to 196.8 F g ~ (-1) when the reaction temperature is 100 鈩，

本文編號：1830553