复杂系统下锂氧气电池正极界面电化学反应机理研究

There have been deeply researches in Li-O2 batteries which operate in a “dry oxygen” system. The reaction mechanism of “electrode/electrolyte/oxygen” interface in the “dry oxygen” system has been proven and the performance of electrode has entered the stage of progressively optimizing process. However, this “dry oxygen” system is unable to meet the requirements of performance improvement and practical application. This project aims to extend the ‘dry oxygen’ system to a complex system that contains CO2, H2O and N2, take the porous cathode/ electrolyte surface of Li-O2 battery under this complex system as the research object, systematically investigate the reaction mechanism, stability of porous cathode. This project innovatively employs a sequence of in-situ electrochemical methods such as differential electrochemical mass spectrometry, EQCM method, superoxide radical simulation and the combination of isotopic tracing of 13C and GC-MS. We want to thoroughly investigate the electrochemical reaction process of mixed gas at electrode/ electrolyte surface, mechanism of carbon corrosion and the anodic decomposition mechanism of Li2CO3 and LiOH. At the same time the reaction mechanism of trace amounts of water at porous electrode surface and the stability of electrolyte at complex system also will be researched. The implementation of this project will lay a solid theoretical foundation for the performance improvements and practical application of Li-O2 batteries. radical simulation and the combination of isotopic tracing of 13C and GC-MS. We want to thoroughly investigate the electrochemical reaction process of mixed gas at electrode/ electrolyte surface, mechanism of carbon corrosion and the anodic decomposition mechanism of Li2CO3 and LiOH. At the same time the reaction mechanism of trace amounts of water at porous electrode surface and the stability of electrolyte at complex system also will be researched. The implementation of this project will lay a solid theoretical foundation for the performance improvements and practical application of Li-O2 batteries.

对“干燥氧气”系统中的锂氧气电池研究已较为深入，关于该体系中“电极/电解液/氧气”界面反应机理已基本探明，电极性能逐步优化。但该系统已难以满足电池性能提升和实用化的要求。本申请项目将“干燥氧气”系统扩展到包含CO2、H2O、N2等的复杂扩展系统，以此复杂环境中的锂氧气电池多孔正极/电解液界面为研究对象，系统研究多孔正极反应机制和稳定性。本项目创新地利用一系列电化学在线研究手段如：差分电化学质谱、EQCM监控、超氧根负离子模拟、在线同位素C13-质谱联合跟踪等，深入探究混合气体在电极/电解液界面电化学反应过程、碳材料腐蚀机理、Li2CO3和LiOH阳极分解过程。同时考察电解液中痕量水在多孔电极界面反应机理、电解液在复杂系统中的稳定性等问题。本项目的实施将为锂空气电池性能的提升和实用化打下坚实的理论基础。

锂氧气电池因其超高的比能量被认为是很有前景的下一代电化学蓄电装置。对“干燥氧气”系统中的锂氧气电池研究已较为深入，关于该体系中“电极/电解液/氧气”界面反应机理已基本探明，电极性能逐步优化。本项目将“干燥氧气”系统扩展到包含CO2、H2O等的复杂扩展系统，以此复杂环境中的锂氧气电池多孔正极（金属锂负极）/电解液界面为研究对象，对多孔正极制备优化、反应机制分析、电解质（液）设计、负极优化保护等方面开展了以下工作：.1、探明复杂系统下，空气正极界面反应机制。包括探明二氧化碳还原和碳酸锂分解析出反应机理；提出金属钌催化剂对二氧化碳还原与析出反应的可逆催化调控机制；解析高比表面积碳材料表面吸附水对氧电极的催化路径和性能提升原理；发现氧气和二氧护碳气体在醚类电解液中，对于金属锂负极循环提升的现象，并解析了该现象的机理。.2、设计、制备了一系列高性能的锂空气电池正极催化剂。提出N-甲基吩噻嗪、含有类血红素活性位点的金属有机框架纳米酶，作为锂空气电池高效可溶性液相催化剂；设计制备Ru纳米颗粒、二维MoN单晶纳米片、自支撑结构Ru@超轻泡沫镍等正极催化材料。.3、锂空气电池功能性电解液的设计与性能研究。发现氯甲酸三氯乙酯添加剂能显著提升锂空气电池的倍率性能和循环稳定性。设计出一种高浓度三盐电解液和一种高浓度双盐电解液，提高金属锂负极低过量系数下的库伦效率。.4、研究全固态锂空气电池。采用二维固态核磁共振谱技术观测和研究了固-固界面空间电荷层。设计并制备出可在-70℃超低温下稳定运行的太阳能驱动全固态锂空气电池；以及固态电解质LAGP与电极界面稳定性研究。.以上相关工作在Joule, Energy & Environmental Science, Angew Chem Int Edit, Advanced Materials, Advanced Energy Materials等国际著名期刊上发表，共计SCI论文51篇，申请锂空气电池方面的专利9件。通过该项目的实施，显著提升我国在锂空气电池领域的国际学术界的影响力。进一步获得国家重点研发计划“新能源汽车”重点专项的（课题负责人）和2019年基金委“优秀青年基金”的资助。.