氧化锰基纳米复合电极材料的制备及其电容特性研究

发布时间：2018-08-16 14:26

【摘要】：随着人们生活水平的提高，人们对能源的需求也越来越大，不可再生资源日益枯竭，必然会爆发能源危机，新能源的开发和利用是解决能源危机的有效途径。新能源的开发与利用明显离不开能量的存储，作为高效环保的储能元件，超级电容器成为近年来研究的热点。超级电容器是兼具高比容量和比功率的高效储能元件，电极材料的优劣直接影响到超级电容器的性能。开发性能优良、环保价廉的电极材料是超级电容器发展的方向，当前超级电容器电极材料还存在生产成本高，性能较差的弊端。针对这一点，本文采用微波水热法，研究了纳米氧化锰和纳米氧化锰复合电极材料的制备，并对样品进行表征和电容特性的测试。采用微波水热法，以KMnO4为原料，制备了多种形貌（花球状、空心管、棒状）的纳米MnO2。氧化锰首先生长成由薄片聚集成的花球状δ-MnO2，随着时间推移，薄片卷曲成空管状并从大颗粒中脱落，然后继续在空管内部结晶，生长成实心方棒状的一维α-MnO2。通过将MnO2粉体和作为粘结剂的PEG4000以及作为导电剂的碳粉混合后涂敷在泡沫镍集流体上制备成电极，并进行电容特性测试。结果表明：125℃下保温1h制备的包含花球状和一维管状形貌的样品在5mV/s的扫描速率下比电容最大为199.65F/g。但是随着扫描速率的增大，比电容衰减较快，扫描速率增大到50mV/s时，比电容只保留原来的16%。而125℃下保温2h制备的一维管状的样品在扫描速率为5mV/s下比电容为163.99F/g，扫描速率增大到50mV/s，比电容仍能保持原来的45%。通过微波水热法制备了活性碳纤维布负载纳米氧化锰的复合电极材料，通过改变反应温度和保温时间以及KMnO4浓度，合成出具有不同形貌的的复合材料并对其进行电容测试。结果表明，0.005mol/L KMnO4与ACFC在70℃下保温1h制备的复合材料为类似草坪的δ-MnO2生长在碳纤维表面，厚度为100~200nm，δ-MnO2呈草叶状，叶片厚10nm左右，负载量为2.85mg/cm2。在1mol/L的Na2SO4水溶液中，电势窗口为-0.4~1.5V（vs SCE），扫描速率为5mV/s下，，当反应温度为70℃，反应时间为0.25h，高锰酸钾浓度为0.01mol/L，加入2片大小为3cm×3cm的活性碳纤维布时，复合电极的比电容最大，为57.08F/g，且电极内阻较小。通过微波辐照，利用尿素的还原性，还原氧化石墨烯，添加0.90g尿素在95℃保温150min可以将15ml浓度为0.25mg/ml氧化石墨烯（GO）完全还原为透明度较高、完整性较好的石墨烯。通过微波水热法合成了石墨烯与氧化锰的复合材料，将复合材料与作为导电剂的碳纳米管以及作为PEG4000作为粘结剂混后涂覆在碳纤维纸上干燥后得到电极。将干燥后的电极作为工作电极，采用三电极系统，测试复合材料的CV曲线以及交流阻抗。结果表明：电极在扫描速率为5mV/s的情况下，测得的电极材料的比电容最大为281F/g；随着扫描速率的增加其比电容逐渐变小，但扫描速率为50mV/s时，复合材料的比电容仍保留原来的40.6%，为114F/g。
[Abstract]:With the improvement of people's living standards, people's demand for energy is also growing, non-renewable resources are increasingly exhausted, energy crisis will inevitably erupt, the development and utilization of new energy is an effective way to solve the energy crisis. Container has become a hot topic in recent years.
Supercapacitor is an efficient energy storage element with high specific capacity and specific power. The quality of electrode materials directly affects the performance of supercapacitor. The development of electrode materials with good performance and low environmental protection cost is the development direction of supercapacitor. At present, electrode materials of supercapacitor still have the disadvantages of high production cost and poor performance. In this paper, the preparation of nano-manganese oxide and nano-manganese oxide composite electrode materials was studied by microwave hydrothermal method, and the samples were characterized and the capacitance characteristics were tested.
Nano-MnO2 with various morphologies (flower-shaped, hollow tube, rod-shaped) were prepared by microwave hydrothermal method using KMnO_4 as raw material. Manganese oxide first grew into flower-shaped delta-MnO_2 aggregated by thin sheets. Over time, the thin sheets curled into hollow tubes and fell off from the large particles, and then continued to crystallize in the inner part of the hollow tube and grew into a solid square rod-shaped one. Vitamin A-MnO2. The electrode was prepared by mixing MnO2 powder with PEG4000 as binder and carbon powder as conductive agent and coating on nickel foam collector. The capacitance characteristics of the electrode were tested. The results show that the sample with spherical and one-dimensional tubular morphology prepared at 125 C for 1 h has the largest specific capacitance at 5 mV/s scanning rate. However, the specific capacitance decreases rapidly with the increase of scanning rate, and only 16% of the original capacitance is retained when the scanning rate increases to 50 mV/s. The specific capacitance of the one-dimensional tubular sample prepared at 125 C for 2 h at scanning rate of 5 mV/s is 163.99 F/g, the scanning rate increases to 50 mV/s, and the specific capacitance can still keep 45% of the original.
The composite electrode materials loaded with nano-manganese oxide were prepared by microwave hydrothermal method. The composite materials with different morphologies were synthesized by changing reaction temperature, holding time and KMnO_4 concentration, and their capacitance was tested. The results showed that the composite materials prepared by 0.005 mol/L KMnO_4 and ACFC at 70 C for 1 h were prepared. For lawn-like delta-MnO2 grown on the surface of carbon fibers, the thickness of delta-MnO2 was 100-200 nm, the thickness of delta-MnO2 was grass-like, the leaf thickness was about 10 nm, the loading was 2.85 mg/cm2. In Na2SO4 aqueous solution of 1 mol/L, the potential window was - 0.4-1.5 V (vs SCE), the scanning rate was 5 mV/s, when the reaction temperature was 70 c, the reaction time was 0.25 h, the concentration of potassium permanganate was 0.01 mol/L, and the concentration of potassium permanganate was 0.01 mol/L. The specific capacitance of the composite electrode is 57.08F/g and the internal resistance of the electrode is small when two pieces of activated carbon fiber cloth with the size of 3 cm *3 cm are added.
Graphene oxide (GO) with a concentration of 0.25mg/ml can be completely reduced to graphene with high transparency and integrity by microwave irradiation. Graphene and manganese oxide composite materials were synthesized by microwave hydrothermal method. The composite materials were prepared by adding 0.90g urea at 95 C for 150 min. Carbon nanotubes (CNTs) as conductive agent and PEG4000 as binder were mixed and coated on carbon fiber paper for drying. The CV curves and AC impedance of the composites were measured with a three-electrode system using the dried electrode as working electrode. The maximum specific capacitance of the composite is 281 F/g, and the specific capacitance decreases gradually with the increase of scanning rate. However, when the scanning rate is 50 mV/s, the specific capacitance of the composite remains 40.6% and 114 F/g.
【学位授予单位】：济南大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TQ137.12;TM53

【参考文献】