High rate and long cycle life in Li-O2 batteries with highly efficient catalytic cathode configured with Co3O4 nanoflower
High rate and long cycle life in Li-O2 batteries with highly efficient catalytic cathode configured with Co3O4 nanoflower
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DOI：
10.1016/j.nanoen.2019.103896
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发表时间：
2019-10-01
期刊：
影响因子：
17.6
通讯作者：
Sun, Hui
中科院分区：
文献类型：
--
作者：
Jiang, Zhuo-Liang;Xu, Gui-Liang;Sun, Hui
非水Li-O-2电池的反应机理是基于Li2O2的沉积和分解。在高倍率条件下运行，Li-O-2电池的极化会迅速增加，导致电池的早期容量衰减。因此，精心设计的具有独特结构和优异催化能力的催化剂是提高Li-O-2电池往返性能（尤其是在高电流密度下）的重要途径。在这项工作中，使用2-甲基咪唑（2-MIM）作为结构导向剂合成了由Co3O4纳米片组装的独特纳米花结构。 X射线光电子能谱（XPS）和拉曼光谱显示Co3O4纳米花表面存在丰富的氧空位，这有利于氧还原和析出反应以及较长的往返寿命。密度泛函理论结果表明，具有氧空位的Co3O4催化剂可以促进Li2O2在基底上的润湿并形成Li2O2纳米膜，从而提高Li-O-2电池的放电容量。由于丰富的氧空位、独特的结构和优异的析氧反应的协同效应，Co(3)O(4)纳米花基电池在0.5 A g(-1)和1 A g(-1)的充放电电流密度下分别具有276次和248次循环的超长寿命和1000 mAh g(-1)的放电容量。这项研究揭示了长寿命 Li-O-2 电池催化剂制备的新策略。
The reaction mechanism of non-aqueous Li-O-2 batteries is based on the deposition and decomposition of Li2O2. The polarization of Li-O-2 batteries can be rapidly increased by operation under a high rate condition, resulting in the early capacity fade of the cells. Therefore, a well-designed catalyst with a unique structure and excellent catalytic ability is an important way to boost the round-trip performance of Li-O-2 batteries, especially under high current density. In this work, a unique nanoflower structure assembled with Co3O4 nanosheets is synthesized by using 2-methylimidazole (2-MIM) as a structural directing agent. X-ray photoelectron spectroscopy (XPS) and Raman spectra reveal abundant oxygen vacancies on the surface of the Co3O4 nanoflower, which are beneficial for oxygen reduction and evolution reactions and long round-trip lifetime. Density functional theory results demonstrate that Co3O4 catalyst with oxygen vacancies could promote the wetting of Li2O2 on substrate and formation of a Li2O2 nanofilm, thereby boosting the discharge capacity of Li-O-2 batteries. On account of the synergistic effect of abundant oxygen vacancies, the unique structure, and excellent oxygen evolution reaction, Co(3)O(4 )nanoflower-based cells could deliver ultralong lifetime of 276 and 248 cycles with a discharge capacity of 1000 mAh g(-1) under charge/discharge current densities of 0.5 A g(-1) and 1 A g(-1), respectively. This study has shed light on a new strategy for catalyst preparation for long lifetime Li-O-2 batteries.