锂氧气电池钙钛矿型催化剂的制备及其电化学性能的研究

发布时间：2018-05-09 12:35

  本文选题：锂氧气电池 + 钙钛矿型氧化物　； 参考：《天津大学》2014年硕士论文

【摘要】：锂氧气电池是特殊的锂空气电池，两者的反应机理是相同的，只是在结构和工作环境上有差异。本文简要概述了锂空气电池的研究进展，及空气电池正极所用催化剂的种类，特别是钙钛矿型复合氧化物的研究现状及进展，并对几种常用制备钙钛矿型氧化物的方法做了简要介绍。通过查阅文献并结合本实验室的情况，最终选用溶胶-凝胶法制备钙钛矿型氧化物作为锂氧气电池的正极材料。 首先，研究传统溶胶-凝胶法合成钙钛矿型LaNi0.8Co0.2O3的最佳条件，并研究了用其作为锂氧气电池正极催化剂的电化学性能。本实验以金属硝酸盐为原料，研究制备过程中络合剂柠檬酸和分散剂乙二醇的含量、pH、反应温度、煅烧温度及时间对制备钙钛矿型LaNi0.8Co0.2O3结构、形貌和电化学性能的影响，并对其进行物相分析和电化学性能测试。结果表明：用胶-凝胶法，以柠檬酸为络合剂，乙二醇为分散剂，pH为8，n乙二醇:n酸:n总金属=2:2:1，90℃水浴加热5h，空气中700℃煅烧3h时制备出的LaNi0.8Co0.2O3结晶度好，颗粒粒径小，分散均匀，电化学性能好。以Super为碳材料，0.1C和截止放电电压为2V时，锂氧气电池首次放电比容量为2152mAh g-1；限制充放电时间为4h时，保持电压在2V以上可循环30圈；当电流增大到0.2C，设置充放电时间为2h时，保持电压在2V以上可循环25圈。 其次，研究了气体扩散电极的制备工艺。以LaNi0.8Co0.2O3为锂氧气电池的正极催化剂，通过Super P、乙炔黑和石墨烯三种碳材料对其电化学性能影响的对比，发现石墨烯的电化学性能最好。进而又对气体扩散电极的催化剂和聚偏氟乙烯用量进行优化，得出当石墨烯：催化剂：聚偏氟乙烯=8:1:1时，0.1C和截止放电电压为2V，首次放电比容量达到2223mAh g-1。 最后，用AgNO3做为银源，用抗坏血酸还原剂，制备出LaNi0.8Co0.2O3/Ag样品，研究了LaNi0.8Co0.2O3/Ag形貌和电化学性能。结果表明：把Ag包覆到LaNi0.8Co0.2O3上，，样品的颗粒稍变小，结晶度不变；以LaNi0.8Co0.2O3/Ag为气体扩散电极的催化剂，石墨烯：催化剂：聚偏氟乙烯=8:1:1时，在0.1C和截止放电电压为2V下，其首次放电比容量为2854mAh g-1；当0.4C时，首次放电比容量急剧减少到910mAh g-1。当设置其充放电时间为4h，0.1C时，放电电压保持在2V以上可循环60圈。
[Abstract]:Lithium-oxygen battery is a special lithium air battery. The reaction mechanism is the same, but the structure and working environment are different. In this paper, the research progress of lithium-air batteries and the types of catalysts used in the cathode of air batteries, especially perovskite-type composite oxides, are briefly reviewed. Several methods of preparing perovskite oxides are briefly introduced. Perovskite oxides were prepared by sol-gel method as cathode materials for lithium-oxygen batteries. Firstly, the optimal conditions for the synthesis of perovskite-type LaNi0.8Co0.2O3 by traditional sol-gel method were studied, and the electrochemical performance of perovskite LaNi0.8Co0.2O3 as cathode catalyst for lithium-oxygen battery was studied. The effects of the content of citric acid and dispersant ethylene glycol, pH, reaction temperature, calcination temperature and time on the structure, morphology and electrochemical properties of perovskite-type LaNi0.8Co0.2O3 were studied. Phase analysis and electrochemical performance tests were carried out. The results showed that the LaNi0.8Co0.2O3 prepared by gelatin-gel method, citric acid as complexing agent, ethylene glycol as dispersant, pH = 8% ethylene glycol: n: n total metal was heated in water bath at 2: 2: 1 ~ 90 鈩

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