碳基催化剂的原位制备及其在锂—空气电池中的应用

发布时间：2018-04-05 19:30

本文选题：电动汽车　切入点：锂-空气电池　出处：《合肥工业大学》2017年硕士论文

【摘要】：作为下一代储能设备,锂-空气电池因其超大的理论比能量(11400 Wh/kg)和理论比容量(3860 mAh/g)、环境友好、结构相对简单和低成本等优点已经成为学术研究人员的主要研究对象。然而,锂-空气电池依然存在一些重要科学问题阻碍其广泛商业化应用,其中电池充放电过电位高是锂-空气电池面临的主要问题,寻找催化活性优异、导电性高、比表面积大、孔隙分布均匀和成本低的正极催化剂是解决上述问题的主要途径,基于此,我们从经济效益和实用性角度出发,采用简单易行的方法原位制备碳基催化剂,得到最优的活化方法,并探索了不同碳材料以及活化后的碳材料对有机体系锂-空气电池的影响。本论文中,我们首先使用最基础的碳纸材料作为锂-空气电池正极材料,通过创新性结合锂离子电池充放电机理,利用锂离子电池放电过程中的嵌锂机制,破坏碳纸原始结构得到比表面积更大、活性位点更多的碳材料,有效提高碳纸的催化性能,再次应用到锂-空气电池正极上时可以得到循环性能相对优异,电池过电位明显降低的锂-空气电池。我们采用控制变量法对几乎无催化活性的碳纸进行了一系列锂化处理。处理方式分别为在不同电流倍率和不同放电深度下对碳纸进行锂离子放电,其中采用0.1 C的电流,0.01 V的放电深度对原始碳纸进行锂化处理可以获得相对最优异循环性能和相对最低的充放电过电位的锂-空气电池,在电流大小为0.03 mA,充放电区间为2.2-4.5 V,放电比容量截至为1 mAh的条件下进行锂-空气电池测试,其电池循环性能达13次,电池首次充放电电压区间低至2.7 V-3.49 V。其次,我们结合上一章中探究得到的最优化锂化处理方式,对CNT,自制Co-CNT,Graphene和Super P四种碳材料进行电化学处理,处理方式为0.1 C电流下锂离子放电至0.01 V,处理后的材料直接用于锂-空气电池测试。我们发现四种碳材料在未处理时锂-空气电池性能较差,锂化处理后的材料结构发生变化,催化活性增强,电池循环性能和电池过电位都有所改善,特别是在过电位上,四种碳材料充电过电位平均降低0.75 V。
[Abstract]:As the next generation of energy storage equipment, lithium-air battery has become the main research object for academic researchers because of its super large theoretical specific energy ratio of 11400 mg / kg and theoretical specific capacity of 3860 mAh / g / g, environment-friendly, relatively simple structure and low cost.However, some important scientific problems still exist in lithium-air batteries. Among them, high charge-discharge overpotential is the main problem facing lithium-air batteries.The cathode catalyst with large specific surface area, uniform pore distribution and low cost is the main way to solve the above problem. Based on this, we adopt a simple and feasible method to prepare carbon based catalyst in situ from the point of view of economic efficiency and practicability.The optimal activation method was obtained and the effects of different carbon materials and activated carbon materials on the lithium-air batteries were investigated.In this thesis, we first use the most basic carbon paper material as the cathode material of lithium-air battery. Through the innovative combination of the charge and discharge mechanism of lithium ion battery, we utilize the lithium intercalation mechanism in the discharge process of lithium ion battery.When the original structure of carbon paper is destroyed, the carbon materials with larger specific surface area and more active sites can be obtained, and the catalytic performance of carbon paper can be improved effectively. When the carbon paper is applied to the positive electrode of lithium-air battery, the cycling performance is relatively excellent.The overpotential of the battery is significantly reduced by the lithium-air battery.A series of lithium treatment was carried out on carbon paper with little catalytic activity by controlling variable method.The method of treatment is to discharge carbon paper with lithium ion at different current rate and different discharge depth respectively.The Li-air battery with the best cycling performance and the lowest charge / discharge overpotential can be obtained by using 0.1 C current and 0.01 V discharge depth to treat the original carbon paper.When the current is 0.03 Ma, the charge / discharge range is 2.2-4.5 V and the specific discharge capacity is up to 1 mAh, the battery cycle performance is up to 13 times, and the initial charge and discharge voltage range of the battery is as low as 2.7 V-3.49 V.Secondly, combined with the optimized lithium treatment method in the previous chapter, we carried out electrochemical treatment of four kinds of carbon materials: CNT, Co-CNT Graphene and Super P.The treated material was directly used in the test of lithium-air battery after the lithium ion discharge reached 0.01 V at 0.1 C current.We found that the performance of the four carbon materials was poor in untreated lithium-air batteries. After lithiation treatment, the structure of the materials changed, the catalytic activity was enhanced, and the cycle performance and overpotential of the cells were improved, especially in the over-potential.The overpotential of four carbon materials decreased by 0.75 V on average.
【学位授予单位】：合肥工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O643.36;TM911.41

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