Li/CO2-O2和Li/CO2电池分级多孔NiO/石墨烯正极的构建及电化学性能研究

Development of high specific batteries has become one of the leading topics in the research field energy storage devices. Rechargeable Li/CO2-O2 and Li/CO2 batteries offers a promise for very high energy density. However, to make this happen, major fundamental scientific breakthroughs are needed that could address various bottlenecks associated with their poor cycle life and power performance. It is because of serious polarization and difficult-to-decompose Li2CO3. Therefore, it is very important to study the influences of morphology and structure on cathode. As a consequence, hierarchical porous material (nickel oxide/graphene, NiO/graphene) will be prepared in this work.The hierarchical porous NiO/graphene will be synthesized by hydrothermal method and microwave radiation. Firstly, the regulation effects of the preparation methods on the morphlogy, composition and structure of NiO/graphene material will be studied in detail. Secondly, electrochemical perfor-mance of cathode made of NiO/graphene will be studied by various test methods. Thirdly, the relationship between cathode electrochemical performance and the morphlogy, composition and structure of material. The important factors affecting the electrochemical performance of the materials and the corresponding mechanism of electrochemical reaction will be discovered. And a theoretical technical foundation for high energy density, long cycle life cathode of Li/CO2-O2 and Li/CO2 batteries will be established.

发展高比能量电池是电化学储能器件研究的前沿课题之一。Li/CO2-O2和Li/CO2电池比能量高、环境友好，然而正极放电产物Li2CO3难分解、电池极化严重，导致其循环寿命短、功率性能差。研究形貌、结构与电极性能的关系，是改善Li/CO2-O2和Li/CO2电池性能的关键。因此，本项目提出设计组装分级多孔NiO/石墨烯正极，拟采用水热法和微波技术构建分级多孔NiO/石墨烯材料，研究合成方法对材料的形貌、组成以及结构的调控规律，研究上述材料构筑的正极在电池中的电性能，研究材料形貌、组成以及结构与正极电性能相互关系并确定影响电性能的关键因素，探讨相关电化学反应机理，为高比容量、高循环稳定性的Li/CO2-O2和Li/CO2电池正极材料的设计提供研究依据。

新型储能器件因其转换率高、易于构建和储存方便等优势越来越多受到人们重视，其中锂氧电池比能量密度高达3500 Wh kg-1以上。然而,该体系存在许多难题，如容量发挥较差、循环效率较低、电解质易分解和循环寿命短等。主要原因如下：1）充放电反应过程中副反应严重；2）高效催化剂匮乏。基于此，本项目开展了设计构筑套层微纳结构球形NiO、微纳二次结构Pt/NiO和CNT/NiO微球的研究工作。采用水热法制备多层纳米球结构的NiO材料在恒流测试条件下，放电截止电压为2.0 V时，放电比容量可以达到3040 mAh g-1。此外，在0.1 mA cm-2恒定比容量800 mAh g-1条件下，可以循环50次以上。微纳二次结构Pt/NiO双效复合催化剂，在恒流测试条件下，放电比容量可达到2329 mAh g-1，恒流循环20次依然可以保持放电比容量在900 mAh g-1以上。在恒容800 mAh g-1条件下，电池可以稳定循环47次。海胆状CNT/NiO材料，其放电容量为4639 mAh g-1，在恒容500 mAh g-1和恒容800 mAh g-1条件下分别循环30次。电流密度为100mA g-1时，氮硫共掺杂石墨烯负载NiO复合材料（N,S-3DG@NiO），作为锂氧电池正极催化剂时，电流密度为100mA g-1条件下，放电比容量达到17300mA h g-1，作为Li-CO2电池的正极催化剂时，放电比容量为13400 mAh g-1。.本项目主要探讨了影响二次微纳结构球状NiO 的生长的因素，阐明其生长机理；通过研究其组成、形貌、结构、表/界面化学与电化学催化性能之间的构效关系，揭示二次微纳结构球状NiO材料催化机理。此外，还研究了氮硫共掺杂石墨烯负载NiO复合材料制备、结构与其催化性能之间影响规律，并探讨了其作为锂氧电池和锂二氧化碳电池正极材料的电化学性能与结构之间的影响规律。