锂空气电池正极界面催化的机制研究与微观结构设计

Due to a high specific energy density, Li-air battery is considered as one of important energy storage technologies which can be applied in electric vehicles. However, a practical application of Li-air battery is currently prevented by the sluggish kinetic rates of charging and discharging reactions which further leads to many electrochemical problems such as high overpotential, poor cyclic performance, low current density, unstable electrodes, and electrolyte decomposition. Therefore, developing a highly active bifuncational catalyst to improve kinetics is a hot topic in the research field of Li-air battery. In this project, the joint first-principles calculations, microscopic structure characterization, and electrochemical measurement will be performed to study solid-solid interfacial catalysis on charging and discharging reactions by transition metal oxides, carbide, and nitrides, to unravel structural characteristic of a highly active catalyst. Further, we will correlate bifuncational catalytic activity with surface structure, interfacial structure, electron transfer, adsorption energy of O2, and finally obtain structural characteristic of highly active catalyst. Based on microscopic structure design and crystal predict, the highly active bifuncational catalysts are predicted to improve the kinetics of electrochemical reactions in Li-air battery. The research project not only solves the fundamental scientific problem of slow kinetic rate of charging and discharging reactions in Li-air battery, but also becomes a typical model of “materials genome” research, and offers a theoretical basis on screening a highly active catalyst.

高比能量锂空气电池是未来大容量纯电动汽车潜在的动力电源技术之一，然而由于充放电动力学速率低限制了其实际性能的提升，导致其充电过电位高、循环性能差、电流密度低、电极材料不稳定、电解质分解等问题。发展高活性双功能的催化剂，提高反应速率是锂空气电池的研究热点。本项目将第一性原理热力学计算与催化剂表面结构表征以及电化学测试结合，研究廉价的过渡金属氧化物、碳化物、氮化物体系对充放电反应的固-固界面催化作用机理，建立催化剂表面结构、界面结构、电荷转移特征、吸附能等对催化活性影响的相关规律，揭示高活性双功能催化剂的特征结构，通过催化剂的表面微观结构设计与晶体结构预测发展新型高活性的催化剂，改善电池电化学性能。本研究不仅解决锂空气电池中充放电反应动力学速率低等基本科学问题，而且为“材料基因组”研究建立典范，为筛选高活性催化剂提供理论指导。

高比能量锂空气电池是未来大容量纯电动汽车潜在的动力电源技术之一，然而由于充放电动力学速率低限制了其实际性能的提升，导致其充电过电位高、循环性能差、电流密度低等问题。本项目将第一性原理热力学计算与催化剂表面结构表征以及电化学测试结合，研究廉价的过渡金属氧化物、碳化物、氮化物体系对充放电反应的固-固界面催化作用机理，建立催化剂表面结构、界面结构、电荷转移特征、吸附能等对催化活性影响的相关规律，通过催化剂的表面微观结构设计与晶体结构预测发展新型高活性的催化剂，改善电池电化学性能。通过本项目的研究，提出“表面酸性”和“能级匹配”作为锂空气电池正极充电反应界面催化活性的理论筛选规则，理论预测了Co3O4、TiC、IrO2，Cr2O3，MnN等高电化学活性的催化剂；设计构建强电荷转移能力材料与导电体纳米复合的ZnO/VACNTs电极结构，实现放电产物为类超氧化物的锂空气电池，揭示锂空气电池放电产物成分调控的纳米尺寸效应与电极界面效应，充电电压降低3.5V和循环寿命提高到150次。本研究不仅解决锂空气电池中充放电反应动力学速率低等基本科学问题，而且为“材料基因组”研究建立典范，为筛选高活性催化剂提供理论指导。