【作者】 孙丽洁；

【导师】 刘晓霞；

【作者基本信息】 东北大学 ， 材料物理与化学， 2008， 博士

【摘要】 本文研究了导电聚合物聚苯胺(PANI)与γ-晶态二氧化锰γ-MnO2、非化学计量氧化锰MnOx、纳米二氧化锰nm-MnO2及其苯胺甲基三乙氧基硅烷(ND42)修饰纳米粒子nm-ND42-MnO2的原位电化学复合,获得了纤维状或三维疏松多孔聚苯胺/氧化锰复合膜。研究了原位聚合对产物形貌及电化学等性能的影响。以复合膜为电极材料组装了对称型模拟超级电容器,探讨了其在超级电容器领域的应用。在0.5 mol·L-1 H2SO4溶液中,通过Mn2+在阳极表面电化学氧化生成γ-MnO2的反应与苯胺(Ani)阳极氧化聚合组合,实现了PANI与γ-MnO2的原位复合。原位复合改善了Ani聚合微环境,获得的复合膜PANI/γ-MnO2以纤维状结构存在。在酸性溶液中,该复合膜的循环伏安曲线显示出PANI典型的氧化还原峰。粉末X-射线衍射(XRD)检测结果表明,复合膜中氧化锰以γ-MnO2形式存在。X-射线光电子能谱(XPS)分析也表明锰以Mn(Ⅳ)价态存在。复合膜在1.0 mol·L-1 NaNO3(pH1)电解质溶液中,0-0.65 V (vs. SCE)的电位范围内具有良好的电容性能。在含50 mmol·L-1 Mn2+溶液中制备的复合膜PM250比电容最大,达到了532F/g(2.4 mA/cm2充放电电流密度),比在相似条件下制备的PANI的比电容高26%。1200次恒电流充放电(5.0 mA/cm2充放电电流密度)循环后,比电容为初始比电容76%,但库仑效率稳定在97.5%以上。以PM250为电极材料,1.0 mol·L-1 NaNO3(pH 1)为电解液组装了对称型模拟超级电容器,在2.4 mA/cm2+充放电电流密度下,比电容达到124 F/g。在近中性体系中(pH=5.6),Mn2+在阳极表面电化学氧化生成了非化学计量的锰氧化物MnOx,通过MnOx与PANI的原位电化学复合制备了纤维状结构的复合膜PANI/MnOx。该复合膜PANI/MnOx在酸性溶液中也表现出PANI的典型氧化还原行为。PANI/MnOx的XRD谱图上无明显衍射峰,表明MnOx以无定形结构存在。PANI/MnOx的XPS分析结果表明,锰以+2、+3、+4混合价态存在。复合膜PANI/MnOx在1.0 mol·L-1 NaNO3(pH 1)电解质溶液中,0～0.65 V的电位范围内具有优异的电容性能。在含120mmol·L-1 MnSO4溶液中制备的复合膜PMx120的比电容达到了·588 F/g(恒电流充放电电流密度：1.0 mA/cm2),比相似条件下制备的PANI的比电容(408 F/g)增加了约44%。采用恒电流充放电手段测试复合膜PMx120的循环性能,发现循环1000次后,复合膜PMx120仍可保持初始比电容的90.3%,且表现出比较稳定的98%以上库仑效率。由复合膜PMx120组装成的对称型模拟超级电容器在3.0 mA/cm2充放电电流密度下的比电容达到了112 F/g。研究了nm-MnO2及ND42表面修饰纳米粒子nm-ND42-MnO2与PANI的原位电化学复合,发现用ND42对纳米粒子进行表面修饰后,改善了纳米粒子与PANI的复合。复合膜PANI/nm-ND42-MnO2具有疏松多孔的三维立体结构,其电容性能明显优于基于未修饰纳米粒子制备的复合膜PANI/nm-Mn02。两种复合膜在1.0mol·L-1 NaNO3(CpH1)电解质溶液中,0～0.65 V的电位范围内均具有良好的电容性能。在1.0 mA/cm2充放电电流密度下,复合膜PANI/nm-ND42-MnO2的比电容达到了421 F/g,复合膜PANI/nm-MnO2的比电容达到了358 F/g,而在相似条件下得到的PANI的比电容只有143F/g。以复合膜PANI/nm-ND42-MnO2及PANI/nm-MnO2为电极材料,分别组装了对称型模拟超级电容器。纳米粒子修饰后制备的复合膜PANI/nm-ND42-MnO2组装成的超级电容器在以25 mV/s的扫描速度进行循环伏安扫描时,循环伏安曲线仍近似为对称性良好的矩形,表明该复合膜在高功率超级电容器领域有应用前景。在1.0 mA/cm2充放电电流密度下修饰后的复合膜PANI/nm-ND42-MnO2组装的超级电容器的比电容为84.5 F/g,而采用非修饰纳米粒子制备的复合膜PANI/nm-MnO2组装的超级电容器的比电容为58.3F/g。更多还原

【Abstract】 In-situ hybridizations of conducting polymer polyaniline (PANI) and manganese oxidesγ-MnO2, nonstoichiometric MnOx, nm-MnO2 (manganese dioxide nanoparticles) and nm-ND42-MnO2 (ND42,N-[(triethoxysilyl)methyl]aniline, grafted manganese dioxide nanoparticles) were conducted electrochemically in this thesis. Composite films PANI/y-MnO2 and PANI/MnOx in fibrous structures and PANI/nm-MnO2 and PANI/nm-ND42-MnO2 in 3D granular structures were obtained. Characterizations of the films were conducted by X-ray diffraction (XRD), X-ray photo-electron spectroscope (XPS) and scanning electron microscope (SEM). Electrochemical and pseudocapactive properties of the films were studied by cyclic voltammetry and constant current charging-discharging experiments. Symmetric model capacitors were constructed using the films as electrodes.In-situ hybridization of PANI andγ-MnO2 was realized in 0.5 mmol·L-1 H2SO4 based on electropolymerization of aniline and electrochemical oxidation of Mn2+, which leading to The obtained composite film PANI/γ-MnO2 showed fibrous morphologies due to effective control of secondary growth of the polymer chains, resulted from the adjustment of chemical environment of aniline polymerization by the in-situ deposition ofγ-MnO2. PANI/γ-MnO2 displayed characteristic redox peaks of PANI on cyclic voltammogram measured in acidic aqueous solution. The XRD patterns of PANI/γ-MnO2 showed characteristic peaks ofγ-MnO2, while peaks characteristic of Mn(IV) appeared on Mn 3s XPS spectrum of the composite film. Composite film PM250 obtained from the solution containing 50 mM Mn2+ and 0.4 M aniline demonstrated a specific capacitance of 532 F/g measured through charging-discharging at 2.4 mA/cm2 in 1.0 mol·L-1 NaNO3 (adjust pH to 1), which is 26 % higher than that of similarly prepared PANI. PM250 kept 76% of its capacitance after 1200 cycles of charging-discharging at 5.0 mA/cm2 with a coulombic efficiency(η) of 97.5%.The symmetric capacitor using PM250 as the electrodes showed a capacitance of 124 F/g measured at 2.4 mA/cm2.Nonstoichiometric MnOx was obtained from Mn2+ in neutral aqueous solutions (pH 5.6) electrochemically together with PANI. Composite films PANI/MnOx were obtained in fibrous structures by this in-situ electrochemical co-deposition. There was no distinguished peak on XRD pattern of the composite film, revealing the amorphous nature of MnOx in the film. Manganese existed in a mixed oxidation states of +2,+3 and+4 in the film, based on XPS measurement. The composite films showed good pseudocapacitive behaviors in 1.0 mol·L-1 NaNO3 (pH=1) between 0 to 0.65 V.Composite film PMx120 obtained from the solution of 120 mM Mn2+ showed a specific capacitance of 588 F/g, which is 44 % higher than that of similarly prepared PANI (408 F/g) measured at 1.0 mA/cm2.PMx120 kept 90.3 % of its capacitance after 1000 charging-discharging cycles, with a coulombic efficiency of 98%.The specific capacitance of a symmetric capacitor using PMx120 as the electrodes was 112 F/g measured at 3.0 mA/cm2.In-situ electrochemical co-depositons of PANI and manganese dioxide nanoparticles, nm-MnO2, or ND42 grafted nanoparticles, nm-ND42-MnO2 were conducted to afford composite films of PANI/nm-MnO2 and PANI/nm-ND42-MnO2. Due to effective nanoparticle-template-guiding, composite film PANI/nm-ND42-MnO2 obtained from the ND42 modified nanoparticles showed uniform 3D granular structure and modified pseudocapacitive properties. PANI/nm-ND42-MnO2 displayed a specific capacitance of 421 F/g measured at 1.0 mA/cm2, while the specific capacitance of PANI/nm-MnO2 obtained from the neat nanoparticles was 358 F/g. Both of the composite films showed higher specific capacitance than similarly prepared PANI (143 F/g). Symmetric capacitors using composite films PANI/nm-ND42-MnO2 and PANI/nm-MnO2 as the electrodes, respectively were constructed. The specific capacitances of the capacitors were 84.5 and 58.3 F/g, respectively measured at 1.0 mA/cm2.更多还原