多孔镍钴复合电极的制备及电化学性能研究

PREPARATION AND ELECTROCHEMICAL PERFORMANCE OF POROUS NICKEL-COBALT COMPOSITE ELECTRODE

张雨

11649155

硕士

材料工程

卢周广

2018-06-04

2018-07-06

哈尔滨工业大学

深圳

钴和镍具有良好的导电性、离子吸附性、环境友好和储量丰富等综合优点，可作为电极活性材料的载体，广泛应用于电池工业。但目前工业应用的泡沫镍孔尺寸太大、比表面小，无法满足高能量密度储能电池的发展需求，急需纳米孔径、力学强度高、负载能力强的多孔金属骨架。本文在综述目前国内外多孔金属的研发进展基础上，探索几种牺牲模板法制备镍钴复合泡沫的优缺点，提出镍钴乙酸盐分解结合一定后处理措施的方法制备镍钴复合泡沫材料，并探索了其作为超级电容器三维集流体的应用。本文主要内容从金属泡沫的制备方法入手，先后使用五种制备手段，通过每种手段对多孔镍钴泡沫的孔隙特征影响进行总结并逐层优化，最终研究出一种简单、清洁的制备方法。依据每种方法造孔成型机理不同将其分为两类，一类为腐蚀溶解成孔法，主要由铝粉、氯化钠、纳米氧化铝作造孔剂。铝是一种两性活泼金属，本文利用铝粉这一性质，采用氢氧化钾溶液腐蚀的造孔方法，制备出了具有分级孔结构的镍钴复合泡沫。这种方法原理与实验过程简单，但是其制备的泡沫大孔孔径在 50 μm 左右，小孔孔径几百纳米，仍属大孔范围。氯化钠和纳米氧化铝做造孔剂，同样形成了多孔泡沫结构。但是在溶解腐蚀过程中，由于腐蚀液在与样品接触反应时的不充分性，导致样品中存在难去除残留，这些杂质将极大影响镍钴泡沫作为电极的性能。相比较于铝粉其大孔孔径有了相应减小，但是其孔结构十分不均匀。另一类为分解成孔法，主要由碳酸氢铵等热不稳定物质造孔。相较于腐蚀溶解成孔法，该法具有显著的优点：一、在稳定泡沫结构的煅烧工艺中即可成孔，无需额外的腐蚀过程；二、由于无需额外腐蚀过程所以该法清洁无残留；三、成孔温度易控制，有利于确定最终成型温度。但是其缺点同氯化钠造孔剂一样，孔结构十分不均匀。最后，本文在清洁无残留分解成孔法基础上，通过对镍钴乙酸盐分解规律的探索，研究出一种乙酸盐分解造孔制备多孔镍钴泡沫的方法，制备出了具有均匀孔结构的三维镍钴泡沫。该泡沫具有一定的机械强度，具有作为电极活性物质骨架的应用前景。本文结合两种简单的后处理措施，对该镍钴泡沫用作超级电容器电极集流体的性能进行了探究。本文研究的方法在电化学领域有着广泛的应用前景，所制备的镍钴泡沫具有清洁无残留的均匀孔结构，具有极大承载活性物质能力，可选取适当的后处理措施即可轻易实现活性电极的制备。另外其孔结构还可结合其他方法进行进一步优化，这将对电化学储能材料在解决目前实际问题和应对将来挑战具有重要意义。

Cobalt and nickel have the advantages of good conductivity, ion adsorption, environmental friendliness, and abundant reserves. They can be used as carriers for electrode active materials and are widely used in the battery industry. However, the size of foam nickel hole in industrial application is too large and its specific surface is small. It is unable to meet the development demand of high energy density energy storage battery. It is in urgent need of porous metal skeleton with nanometer aperture, high mechanical strength and strong load capacity.. In this paper, we reviewed the research progress of porous metals at home and abroad and explored several methods for preparing nickel-cobalt composite foams. Then, we proposed a nickel-cobalt acetate decomposition combined with some post- treatment measures to prepare nickel-cobalt composite foams, and explored its application as a three-dimensional collector for supercapacitors.In this paper, starting with the preparation of metal foam, five kinds of preparation methods have been used to summarize and optimize the pore characteristics of porous nickel and cobalt foam by each means, and a simple and clean preparation method is finally studied. According to the different forming mechanism of each method, they are divided into two categories. One is the method of corrosion dissolution and pore formation, and the pore formation agent is mainly aluminum powder, sodium chloride, and nano-alumina. Aluminum is an amphoteric active metal that can be dissolved in potassium hydroxide solution. We have used this property to prepare a nickel-cobalt foam with a large pore diameter of about 50 microns and a small pore diameter of several hundred nanometers. Subsequently, we made porous foams by using sodium chloride and nano-alumina as pore-forming agents. However, in the process of dissolution corrosion of these pore-forming agents, due to the insufficiency of the corrosive solution in the contact reaction with the sample, there are hard-to-remove residues in the sample. These impurities will greatly affect the performance of the nickel-cobalt foam as an electrode. The other type is a method of decomposing pores, which is mainly made of thermal unstable substances such as ammonium bicarbonate. Compared with the corrosion dissolution and hole-forming method, this method has significant advantages: First, it can form holes during the calcinations’ process of the stable foam structure without additional corrosion process; Second, it has no residue due to no additional corrosion process. Third, the pore temperature is easy to control, which is helpful to determine the final molding temperature. However, its disadvantage is the same as sodium chloride pore-forming agent, and the pore structure is very uneven.Finally, on the basis of the clean residue-free decomposing pore method, we explored the decomposition law of nickel-cobalt acetate, developed a method for the preparation of porous nickel-cobalt foam by the decomposition of acetate, and prepared a uniform pore. The foam has a certain mechanical strength and has a promising application as an electrode active material skeleton. We have explored the performance of this nickel-cobalt foam as a supercapacitor electrode current collector by combining two simple post-treatment measures.The method studied in this paper has a wide range of applications in the field of electrochemistry. The prepared nickel cobalt foam has a clean and non residual uniform pore structure and has a great capacity for carrying active material. The preparation of active electrode can be easily achieved by selecting appropriate post-treatment measures. In addition, the pore structure can be further optimized with other methods, which will be of great significance for solving the current practical problems and dealing with the challenges in the future.

多孔金属 镍钴复合泡沫 造孔剂 孔结构 超级电容器 机械性能

porous metal nickel-cobalt composite foam pore-forming agent hole structure supercapacitor mechanical properties

中文

联合培养

南方科技大学

张雨. 多孔镍钴复合电极的制备及电化学性能研究[D]. 深圳. 哈尔滨工业大学,2018.