超级电容器电极材料四氧化三钴颗粒的制备及其性能的研究

发布时间：2018-03-26 05:03

  本文选题：超级电容器　切入点：Co_3O_4　出处：《中北大学》2017年硕士论文

【摘要】：在诸多的过渡金属氧化物中,立方尖晶石型Co_3O_4由于其易于制备、环境友好成本低廉及具有相对较高的比电容等优点,被认为是一种很有潜力的超级电容器材料。但是由于Co_3O_4电极材料导电性差(具半导体性质),导致其在充放电过程中容量衰减较为明显,特别是在大倍率充放电下的循环稳定性能较差,因此开发具有优异电化学性能的Co_3O_4先进功能材料具有重要的意义。近年来,直接生长在集流体上的过渡金属氧化物电极材料,逐渐引起人们的关注,这样不仅可以避免在电极制备过程中使用导电乙炔黑、粘结剂等惰性辅助材料,使得活性材料与集流体间直接接触,并且制作方法简单、得到的电极材料导电性好。本文利用在泡沫镍上直接生长Co_3O_4活性材料,对其不同反应条件进行研究,利用XRD,SEM等分别表征了其形貌、晶体结构,并测试了材料的电化学性能。主要研究工作如下:(1)利用不同钴源制备Co_3O_4,分别得到绣球状,纳米立方体状,饼干状,及片状的Co_3O_4颗粒,并对其进行XRD及形貌表征,并进一步研究了Co_3O_4的形成机理。以Co(NO3)2·6H2O做钴源时,在热分解过程中将会释放出NO2气体,使形成的三维体状Co_3O_4具有疏松多孔的特点;而以CoCl2·6H2O作为钴源时,生成的二维片状Co_3O_4,则不存在这一现象。(2)采用水热-热分解法在进行泡沫镍上负载Co_3O_4电极材料的实验中,通过控制变量,改变水热反应时间、反应时钴离子的浓度及热分解时煅烧温度,对所得产物进行结构及形貌的表征,及电化学性能的测试,结果表明:在水热反应时长12h,溶液中钴离子浓度0.04mol/L,煅烧温度500℃时,所得产物具有良好的电化学性能。在上述最佳实验条件下在泡沫镍上进行Co_3O_4纳米电极材料的制备,并对其结构形貌进行表征及电化学性能进行测试。结果表明:长在泡沫镍基体上的Co_3O_4花状颗粒,比电容最高可达580.10F/g,且在放电电流密度为4A/g时,循环1000次后比电容仍能保持最初的95.703%,具有优异的循环稳定性。(3)采用溶剂热-热分解法制备出单独Co_3O_4电极材料及Co_3O_4/NiO复合电极材料,并对Co_3O_4与NiO比例为1:1,2:1和水热反应加热12h,24h的情况下的电极材料进行制备和电化学性能的研究。结果表明,单独Co_3O_4电极材料的电化学性能比Co_3O_4/NiO复合电极材料好。这可能是由于复合材料的颗粒尺寸较大等原因,因此关于如何提高复合材料的性能方面,还需进一步研究。
[Abstract]:Among all the transition metal oxides, cubic spinel Co_3O_4 has the advantages of easy preparation, low cost and relatively high specific capacitance. It is considered to be a potential supercapacitor material. However, due to the poor conductivity of Co_3O_4 electrode materials (semiconductor properties), the capacity attenuation is more obvious during the charge-discharge process. Especially, the cyclic stability is poor at large rate charge / discharge, so it is of great significance to develop advanced functional Co_3O_4 materials with excellent electrochemical properties. In recent years, transition metal oxide electrode materials have grown directly on the collector. In this way, the inert auxiliary materials such as conductive acetylene black, binder and other inert auxiliary materials can be avoided in the preparation of the electrode, which makes the active material contact directly with the collector, and the preparation method is simple. The electrode materials obtained have good electrical conductivity. In this paper, the morphology and crystal structure of Co_3O_4 active materials grown directly on nickel foam were studied under different reaction conditions. The electrochemical properties of the material were tested. The main research work was as follows: 1) CoS3O _ 4 was prepared by using different cobalt sources. The Co_3O_4 particles in the shape of embroidered ball, nano-cube, biscuit and flake were obtained, and their XRD and morphology were characterized. The formation mechanism of Co_3O_4 was further studied. When Co(NO3)2 6H2O was used as cobalt source, NO2 gas would be released in the process of thermal decomposition, which made the three-dimensional bulk Co_3O_4 porous and porous, while CoCl2 6H2O was used as cobalt source. In the experiment of loading Co_3O_4 electrode material on nickel foam by hydrothermal decomposition method, the reaction time of hydrothermal reaction was changed by controlling the variables. The concentration of cobalt ion during reaction and the calcination temperature during thermal decomposition, the structure and morphology of the product were characterized, and the electrochemical properties were tested. The results showed that the concentration of cobalt ion in solution was 0.04 mol / L, the calcination temperature was 500 鈩，

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