| 题名 | 基于碳材料的高能锂空气电池正极材料的研究 |
| 作者 | 王 珊 |
| 学位类别 | 硕士 |
| 答辩日期 | 2013-06 |
| 授予单位 | 中国科学院研究生院 |
| 授予地点 | 北京 |
| 导师 | 崔光磊 |
| 关键词 | 碳材料 硒化物 锂空气电池 正极 催化剂 |
| 学位专业 | 化学工程 |
| 中文摘要 | 锂空气电池具有超高的能量密度，被认为是最有潜力应用在未来电动汽车发展中的一种电池。由于锂空气电池仍处在初步的研究阶段，很多问题阻碍了其产业化。其中高过电势和低循环性是面临的两个最主要的问题。本文从锂空气电池正极出发，制备具有高稳定性、高催化活性的电极材料，构建高效空气电极，对材料的氧还原性能进行研究，并分别应用于双电解液和纯有机电解液两个体系的锂空气电池，进行充放电测试，考察倍率性能、循环性能，并进行一部分机理探讨工作。氧化石墨表面含有丰富的含氧基团，与具有良好导电性的碳纳米管进行复合，作为一种非金属氧气还原催化剂进行研究。通过对不同含氧量的复合材料进行电化学研究，发现含氧基团的存在能够促进材料催化氧气还原的效果，具体表现为还原电位正移，还原电流信号增大，催化反应由两电子还原变为四电子还原。理论计算的结果表明氧化石墨表面含氧基团的存在有利于对氧气分子的吸附，并能够促进随后的四电子还原反应。制备的氧化石墨/碳纳米管复合材料结合了氧化石墨表面丰富的含氧基团和碳纳米管良好的导电性，用于双电解液锂空气电池，有效地减小了电池的过电势，在0.1 mA cm-2的电流密度下，充放电电压差仅有0.17 V。
采用原位氧化硒化钴纳米带的方法，得到纳米级CoSe2/CoO复合材料，与导电炭黑（Super P）复合，制备锂空气电池正极。比较单纯的Super P和CoSe2/CoO/Super P空气电极的充放电行为，发现加入CoSe2/CoO之后，电池充电电压明显降低，由4.1 V降低到4 V以内，且电极循环稳定性大幅增强，放电十圈后，纯Super P电极的容量保持率仅有22.5 %，而掺入CoSe2/CoO之后，电极容量保持率高达87 %。通过分析首次充电气体产物，发现掺入CoSe2/CoO之后，CO2产物的含量明显降低，表明CoSe2/CoO的加入有效地降低了碳电极与强亲核性试剂（如O2-等）反应的速率，减少了碳电极的分解，从而维持了电极的高稳定性 |
| 英文摘要 | Lithium air battery, which has a high theoretical energy density, has been considered one of the most promising energy storage devices for electric vehicles. Whereas the research of lithium air battery is in its initial stage, there are several problems to be resolved. Among them high overpotential and low cycle life are two main problems. This paper focus on the investigation of the cathode. Materials with high stability and high activity are prepared and investigated as oxygen reduction catalysts. Then hybrid electrolyte and aprotic electrolyte lithium air batteries are fabricated. Rate performance and cycling performance are examined through charge/discharge tests. A primary study of the cathode mechanism of the two systems is also conducted.Graphene oxide, with sufficient oxygen-containing groups, is integrated with electronically conductive carbon nanotube to be explored as an efficient metal-free catalyst for oxygen reduction reaction (ORR). The ORR performance dependent on different content of oxygen-containing groups is evaluated by electrochemical measurements, which show positive shifted onset potential, enlarged current density and calculated transferred electron number per oxygen molecule changes from 2 to 4, revealing evident correlations between ORR electrocatalytic activity and the content of oxygen-containing groups. Theoretical calculations indicate that the existence of oxygen-containing groups is favorable for the adsorption and subsequent four-electron reduction reactions of O2. The hybrid material exhibited a very low overpotential (The voltage gap at 0.1 mA cm-2 is only 0.17 V) and better electrocatalytic performance when attempted as cathode in aprotic/aqueous hybrid electrolyte Li-air batteries, owing to abundant oxygen containing groups on graphene oxide and excellent electroconductivity of carbon nanotube. CoSe2/CoO nanocomposite is prepared by in situ oxidation of cobalt selenide nanobelt. Then the cathode based on the mixture of this composite and Super P is prepared. By comparing the charge-discharge curves of lithium air batteries based on pure Super P and CoSe2/CoO/Super P, it is found that the addition of CoSe2/CoO into the cathode decreases the charge plateau from 4.1 V to 4.0 V and exhibits a more impressive cycle life with 87 % capacity retention for 10 cycles, while that of battery based on pure Super P is only 22.5 %. The composition of the gas released at the end of the first charging cycle is investigated. Compared with pure Super P electrodes, the presence of CoSe2/CoO nanocomposites lower the proportion of CO2. This result confirms that CoSe2/CoO/Super P cathode can protect carbon material from being oxidized by the strong nucleophilic superoxide (such as O2-) during charge process and thus maintains the high stability of the cathode. |
| 语种 | 中文 |
| 学科主题 | 仿生能源系统 |
| 公开日期 | 2013-07-13 |
| 内容类型 | 学位论文 |
| 源URL | [http://ir.qibebt.ac.cn:8080/handle/337004/1509]  |
| 专题 | 青岛生物能源与过程研究所_仿生能源与储能系统团队 |
| 推荐引用方式 GB/T 7714 | 王 珊. 基于碳材料的高能锂空气电池正极材料的研究[D]. 北京. 中国科学院研究生院. 2013. |
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