锰基三元化合物作无粘结剂电极的制备与性能研究

发布时间：2018-10-09 14:11

【摘要】：电化学电容器作为一种具有高能量密度、可大电流充放电、对环境友好的储能元件而备受关注。电极材料作为储能元件的核心组成部分，决定了电化学电容器的性能。近年来，，三元及多元化合物电极材料的开发引起人们的广泛关注，它综合了多种过渡金属的优良性能，具有更高的比电容和良好的循环寿命。另一方面，电极的制备工艺从粘结剂型向无粘结剂型电极转变，让电化学活性材料直接生长于集流体表面，具有简化工艺、提高活性材料利用率的优点。本论文采用水热法，以Mn(CH3COO)2·4H2O、Co(CH3COO)2·4H2O、脲作为原料，在泡沫镍表面一步沉积得到CoMn2O4、MnCo2O4两种电极材料，设计了一种无粘结剂型电极。利用扫描电镜（SEM）、X射线衍射仪（XRD）、X射线能谱仪（EDS），循环伏安法（CV）、恒电流充放电（CP）和电化学阻抗谱（EIS）对电极材料进行结构表征和电化学性能测试。（1）CoMn2O4作为尖晶石结构的过渡金属复合氧化物，作为电极材料有较大的潜在价值。通过调控有机添加剂脲的比例、水热反应时间、水热温度等因素，得到最佳参数：n(Mn):n(Co):n(脲)比例为2:1:1，n(Mn)=20mmol，水热60°C反应20h。在泡沫镍表面沉积了无定形CoMn2O4纳米片，尺寸在200nm左右。比较无粘结剂电极与粉末涂敷电极的电化学性能，无粘结剂比电容可达625.00F·g-1，循环500次后，比电容保持率为65.50％。相同条件下，涂敷电极比电容为252.00F·g-1，比电容保持率为60.54％。（2）MnCo2O4作为尖晶石（AB2O4）的一种，与CoMn2O4相比，A、B位置发生替换、两者价态改变。以钴盐Co(CH3COO)2·4H2O为主体，当n(Co):n(Mn):n(脲)比例为2:1:1，n(Co)=10mmol，水热60°C反应20h后泡沫镍表面生长了300nm左右似花瓣状的MnCo2O4纳米片。通过电化学测试，无粘结剂电极与涂敷电极比电容分别为740.00F·g-1、251.66F·g-1。循环500次后，无粘结剂电极比电容保持率为71.00％，而涂敷电极仅为37.26％。本论文通过简单的水热反应制备了具有良好电化学性能的CoMn2O4和MnCo2O4无粘结剂型电极。通过性能测试比较，无粘结剂型电极在活性材料的利用率以及电化学性能方面要远高于涂敷电极，在简化电极制备工艺的同时提高了活性材料的电化学性能。
[Abstract]:Electrochemical capacitors as a kind of high energy density, high current charge and discharge, environmentally friendly energy storage components have attracted much attention. As a core component of energy storage elements, electrode materials determine the performance of electrochemical capacitors. In recent years, the development of ternary and multicomponent compound electrode materials has attracted wide attention. It integrates the excellent properties of many transition metals, and has higher specific capacitance and better cycle life. On the other hand, the preparation process of electrode is changed from binder form to unbonded form electrode, which makes electrochemical active materials grow directly on the surface of collecting fluid, which has the advantages of simplifying the process and improving the utilization ratio of active materials. In this paper, Mn (CH3COO) 24 H 2O Co (CH3COO) 24 H 2O and urea were used as raw materials to prepare two kinds of CoMn2O4,MnCo2O4 electrode materials by one step deposition on the surface of nickel foam, and an unbonded electrode was designed. The structure and electrochemical properties of the electrode materials were characterized by (EDS), cyclic voltammetry, (CV), constant current charge-discharge (CP) and electrochemical impedance spectroscopy (EIS) by scanning electron microscope (SEM) X-ray diffractometer (XRD) and X-ray energy spectrometer (EDS),). The results are as follows: (1) CoMn2O4, as a spinel structure transition metal composite oxide, has great potential value as electrode material. By adjusting the proportion of organic additive urea, hydrothermal reaction time and hydrothermal temperature, the optimum reaction parameters were obtained: the ratio of 2: 1 (Mn): n (Co): n (urea) was 2: 1: 1: n (Mn) = 20 mmol, and the hydrothermal reaction time was 60 掳C for 20 h. Amorphous CoMn2O4 nanocrystals were deposited on the surface of nickel foam, and the size was about 200nm. The electrochemical performance of the unbonded electrode was compared with that of the powder coated electrode. The specific capacitance of the binder was 625.00 F g-1, and the specific capacitance retention rate was 65.50 after 500 cycles. Under the same conditions, the specific capacitance of the coated electrode is 252.00F g-1 and the retention rate of the specific capacitance is 60.54. (2) as a kind of spinel (AB2O4), MnCo2O4 is replaced by CoMn2O4, and their valence states change. With cobalt salt Co (CH3COO) 2 4H2O as the main body, when the ratio of n (Co): n (Mn): n (urea) is 2: 1: 1n (Co) 10 mmol / mol, 300nm like petal-like MnCo2O4 nanocrystals were grown on the surface of nickel foam after hydrothermal reaction for 20 h at 60 掳C. The specific capacitance of unbonded electrode and coated electrode was 740.00F g-1251.66F g-1, respectively. After 500 cycles, the specific capacitance retention rate of the binder electrode is 71.00, while the coated electrode is 37.26. In this paper, CoMn2O4 and MnCo2O4 unbonded electrodes with good electrochemical properties were prepared by simple hydrothermal reaction. The results show that the utilization ratio and electrochemical performance of the unbonded electrode are much higher than that of the coated electrode. The electrochemical performance of the active material is improved while the preparation process of the electrode is simplified.
【学位授予单位】：浙江理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TM53;TQ137.12

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