锂空气电池氧电极构效关系及三维化研究

In recent years, research on the catalystic material of lithium-air batteries has made progress continuously, but the structure-activity relationship of the catalyst is not yet clear and still lacking distinct catalyst design ideas. At the same time, although the noble metal catalysts (Pt, Pd, Ru etc.) showed excellent catalytic performance for the oxygen electrode, because of their limited resources, they need to be substitute by non-noble metals with much lower price. This project aims to study the structure-activity relationship and three-dimensional structure of non-noble metal oxygen electrode for lithium-air batteries. First by using planar electrodes, we want to reveal the relationship of the following three, which are the key properties of the oxygen electrode catalyst, the morphology and physical/chemical properties of Li2O2, and the electro-catalytic performance of catalysts. Combining with the density functional theory (DFT) calculations, this study will quantitatively describe the properties of the catalyst that determine the performance of the electrode, and then applied it to the design of three dimensional non-noble metal electrodes. In this project, by combining the basic study on the structure-activity relationship of catalyst and the practical application of 3D network structure of electrode, it is expected to get both excellent catalytic performance and high capacity lithium-air battery with non-noble metal oxygen electrode, which will not only has the basis of scientific value, and also play a guiding role in actual application.

锂空气电池催化剂方面的材料研究近年来不断取得进展，但催化剂本身的构效关系尚未明确，仍缺乏清晰的催化剂设计思想。同时，尽管贵金属催化剂（Pt、Pd、Ru等）表现出优异的氧电极性能，但由于其资源受限，需要使用价格低廉的非贵金属替代。本项目拟开展锂空气电池非贵金属氧电极构效关系与三维化研究。将先通过平面电极的研究，揭示有机介质氧电极的“催化剂关键性质-Li2O2形貌与物理化学性质-电催化性能”三者之间的联系，结合密度泛函理论计算(DFT)对决定电极性能的催化剂关键表面性质进行指认与定量描述，然后将之应用到非贵金属三维网络电极的设计中。本项目将催化剂构效关系的基础研究与针对实际应用的三维网络电极结构相结合，有望获得兼具优良催化性能与高容量的锂空气电池非贵金属氧电极，既具有基础科学价值，也将对实际应用起指导作用。

寻找高效的氧电极催化剂是锂空气电池的重要研究方向。当前锂空气电池的氧电极催化剂的相关材料研究并不缺乏，但清晰、系统的催化剂构效关系则研究较少。清晰的构效关系研究对指导高效催化剂的设计具有重要意义。本项目通过明确、系统的实验，使用磁控溅射方法研究了十多种平面模型电极对锂空气电池氧电极的催化性能，通过将放电产物Li2O2形貌这一特殊参数作为指纹，结合DFT理论计算模拟揭示了不同金属表面对氧或超氧离子的吸附能差异是导致放电产物Li2O2形貌差异的根本原因。同时明确指出不同形貌的Li2O2同时具备不同晶型。这种晶型的差异是导致后续充电平台差异的主要原因。这对指导锂空气电池氧电极高效催化剂的设计与合成具有清晰、明确的指导意义。其中重要结果及创新点如下：.1..使用磁控溅射法批量、可控的制备多种金属模型电极，方便平行的性能比较；.2..自制适合平面模型电极研究的锂空气电池测试装置；.3..使用DFT计算不同模型电极表面的LiO2吸附能，将其作为指纹与相应锂空气电池充放电性能进行关联；.4..清晰揭示锂空气电池氧电极催化活性及放电产物Li2O2形貌存在对应性，结合DFT计算发现这种现象的物理本质是由表面对ORR中间体LiO2的吸附作用强度决定的。.5..使用金属盐悬浊液沉积法成功制备多种三维网络金属电极。