钠离子电池用磷/褶皱氮掺杂石墨烯负极材料的理性构建与性能研究

Room-temperature sodium-ion batteries have attracted great interest due to the huge abundant sodium resources and their low cost. Phosphorus is a promising candidate for sodium-ion battery anode because of its high theoretical capacity of 2600 mAh/g and low-cost nature. Despite encouraging advantages, the practical application of phosphorus anode is highly hindered by low electrical conductivity and large volume change of phosphorus in the cycling. In this project, we will design and synthesize highly crumpled nitrogen-doped graphene supported phosphorus nanoparticles as anode for sodium-ion battery, in which the doped graphene sheets can greatly improve the electronic conductivity and maintain the electrode structure while stabilize the solid-electrolyte interphase (SEI). The structure, morphology, and electrochemical performance of the phosphorus/crumpled graphene composite will be systematically investigated through multiple characterization techniques, such as SEM, TEM, XPS, and EIS. Moreover, the structure-performance relationship will be further discussed based on the aforementioned experimental analysis to clarify the mechanism of the composite anode of sodium-ion battery. The facile synthesis approach, rationally designed structure together with the clarified electrochemical mechanism will be greatly helpful for the design and fabrication of novel high-performance-electrodes with large volume change during cycling.

室温钠离子电池由于其低成本、材料来源广泛等优势成为新一代储能体系的热门选择。磷基负极材料具有很高的理论容量(2600 mAh/g)且价格低廉，极具发展潜力。然而，差的电子电导率和脱嵌钠离子引起的巨大体积膨胀易导致实际容量偏低和容量的快速衰减，严重阻碍其大规模应用。本项目拟利用具有高孔容的褶皱型氮掺杂石墨烯作为导电基体，通过“升华-沉积”法负载磷纳米颗粒到掺杂石墨烯的微/介孔内，以显著改善磷基负极材料电导率和稳定磷的纳米结构及固态电解质膜，解决困扰磷负极的核心问题。通过透射/扫描电镜、X-射线光电子能谱、电化学阻抗等手段研究复合材料的结构和电化学性能，明确石墨烯孔结构、掺杂量、沉积温度等制备参数对复合材料的纳米结构及电化学性能的影响。探寻影响室温钠离子电池用磷基负极性能的核心因素，并揭示其构效关系和内在机理，为具有大体积膨胀的电极材料的设计和制备提供有益借鉴和参考。

近年来，以太阳能、风能为代表的新能源产业的快速发展迫切需要新型低成本、安全、高比能非锂离子储能体系，以取代或部分代替锂离子电池，推动相关新兴领域的健康发展和保证我国能源战略安全。室温钠离子电池由于其低成本、材料来源广泛等优势成为下一代储能体系的热门选择。与碳基负极材料相比，磷基负极材料理论比容量高且价格低廉，发展潜力巨大。然而，红磷其本身低的电子电导和循环过程中巨大的体积变化，会使得其储钠性能迅速下降，严重阻碍其大规模应用。. 本项目设计并构筑了褶皱型氮掺杂石墨烯负载无定型红磷，利用褶皱型氮掺杂石墨烯的高电子、离子导电性和结构稳定性三者增强协同效应，实现了磷基负极材料在钠离子电池中的长循环寿命及高倍率性能的突破。对比了碳球、碳纳米管和氮掺杂石墨烯负载磷负极的结构及性能差异，揭示了影响磷/碳复合负极电化学性能的关键因素。确定了“升华-沉积”法最优热处理条件，避免了白磷的生成。掺杂石墨烯的孔体积决定了磷的最高含量，过多磷的载入易在嵌钠过程中由于过大的体积膨胀导致结构崩塌。我们还发现构建磷与碳之间的化学键可明显提升结构稳定性，实现磷负极的长寿命和高库伦效率。. 本项目所发展的大比表面积、高掺杂量石墨烯材料有望在催化、高分子复合材料、生物医用材料取得应用。此外，本项目发展的磷/碳复合材料等具有长循环寿命和高容量等特性，是钠离子电池中负极的理想选择，有望应用于大规模储能等技术领域，满足国家重大技术需求。本项目所发展的电极设计思路有望作为一种普适方法，为其他储能材料的设计和研究提供一种新的研究思路。