【作者】 赵峰鸣；

【导师】 马淳安；

【作者基本信息】 浙江工业大学 ， 工业催化， 2005， 博士

【摘要】 锰氧化物尤其是二氧化锰在电池和催化工业中已得到广泛的应用,其品质对电池的性能和催化剂的活性起着决定性的作用,因此合成高活性的锰氧化物显得非常重要。本文选用锰氧化物作为研究对象,首次利用喷雾热解法制备了超细粉体材料,并通过喷涂法制作成Ni-MnO_x薄膜电极,采用SEM、XRD、TG、AFM、激光粒度仪等多种材料分析手段和恒电流、恒电位、线性慢扫描、循环伏安、电化学阻抗谱等电化学实验方法,对碱性介质中锰氧化物的电化学性能和锰氧化物催化剂上氧的电催化还原进行了研究,同时深入考察了二氧化锰放电中间态粒子对氧的电催化还原的影响。 本文在第三章中,首次利用喷雾热解法合成了锰氧化物超细粉体（Mn₃O₄、Mn₂O₃、Mn₅O₈、α-MnO₂、β-MnO₂、γ-MnO₂和λ-MnO₂）,对合成样品的成分、结构和形貌进行表征和分析,考察了其在碱性介质中的电化学性能。研究发现,锰氧化物主要是300℃时前驱体的燃烧产物,通过燃烧有利于微粉超细化。喷雾干燥后的粉末呈空心球形,表面光滑且有裂口。热处理增加了颗粒的团聚,团聚体比较松散,是由最小粒径约0.1 μm小颗粒聚集而成。酸化处理是获得高含量MnO₂样品的有效途径,样品E、F和H的组成和纯度均高于商品EMD。样品G、E和F的电化学性能优异,初始放电容量最高可达215 mAh·g^-1,放电深度比EMD提高15%。对γ-MnO₂电极在不同阴极极化电位下的电化学阻抗行为的研究发现质子在二氧化锰晶格中的扩散符合多孔电极的阻挡层扩散模型。 在第四章中,利用原子力显微镜（AFM）观察Ni-MnO_x真电极的表面形貌,通过恒电位阶跃法估算其真实表面积,研究了二氧化锰放电中间态粒子对还原动力学的影响。研究发现,通过喷涂法制作的薄膜电极表面沉积的是样品中粒度分布小于10%的部分。其电化学真实表面积按下列顺序递减:α-MnO₂>γ-MnO₂>β-MnO₂>Mn₃O₄≈Mn₂O₃>λ-MnO₂>Mn₅O₈。经快速循环伏安研究,在Mn₅O₈和α、β、γ-MnO₂电极中检测到了中间态粒子的还原过程,但在电化学活性较低的Mn₃O₄、Mn₂O₃和λ-MnO₂中均没有出现。这表明二氧化锰电极的电化学活性更多还原

【Abstract】 Manganese oxides, especially manganese dioxide, are widely used in the field of battery and catalysis. Its quality is vital to battery performance and catalysis activity. Therefore, it is all-important to prepare the active manganese oxides. Based on the review of research and development of manganese oxides, spray drying was used to prepare the ultra-fine powders and Ni-MnO_x film electrode was made by mist spray for the first time. The electrochemical reduction of manganese oxides and electro-catalysis reduction of oxygen on some manganese oxides in alkaline solution were investigated by different material characterization methods and electrochemical techniques, such as SEM, XRD, TG, AFM, laser-granularity, linear polarization, cyclic voltammetry and electrochemical impedance spectroscopy.In the third chapter of this dissertation, ultra-fine manganese oxides was firstly prepared by spray drying, such as Mn₃O₄, Mn₂O₃, Mn₅O₈, α-MnO₂, β-MnO₂, γ-MnO₂ and λ-MnO-2. The component, structrue, morphology and electrochemical performance were studied. It is found that manganese oxides was formed at 300 °C by burning precursor. This burning process is propitious to obtain ultra-fine powders. The SEM showed global precursor was hollow. Being heat-treated, particle was formed conglomeration which was made up of smaller particle of 0.1 μm. Acid treating could offer the samples with high content MnO₂. The composition and purity of sample E, F and H was higher than commercial EMD. Particularly, electrochemical performance was good with an initial discharge capacity of 215 mAh·g^-1. The proton diffusion process in MnO₂ was studied by using the transmission block model of porous electrode.In the fourth chapter, the techniques of atom force microscope and potential steps were used to examine the texture and surface chemical area of Ni-MnO_x film electrode. The effect of reduction kinetics on discharged intermediate spieces was studied by fast cyclic voltammetry in alkaline solution. The experimental results更多还原