氮掺杂碳骨架中金属锂形核规律研究

Li metal batteries (LMBs) are strongly considered as the next-generation energy storage systems due to their ultra-high energy density (3~5 higher than that of traditional Li ion batteries). However, dendrite growth and infinite volume expansion on the Li metal anodes severely hinder the practical applications of LMBs. The plating of Li is actually a hostless process, which may induce immense internal stress fluctuation of battery and account for seriously deteriorated performance. Carbon matrix with a high specific surface area, controllable pore structure can provide a depositing site for Li metal and relieve the volume change during repeated Li plating/stripping. The tunable surface chemistry can effectively regulate the depositing behavior and suppress lithium dendrite growth. However, the nucleation and growth mechanism of Li metal in carbon matrix is unclear. This severely hinders the exploitation of effective host materials of Li metal anode. .This project focuses on the nucleation mechanism of Li metal in lithiophilic N-doped carbon matrix. Firstly, N-doped carbon with tunable surface properties including doping content, type, and location of nitrogen heteroatom, specific surface area, pore structure can be obtained. Through clear analysis on the relationship between diffusion/deposition behavior of Li metal and the surface properties of N-doped carbon, principles to design effective host materials with dendrite-suppressing ability can be achieved. Understanding on the deposition behavior of Li metal in these hosts can shed lights on the rational design and controllable synthesis of functional N-doped carbon /Li composite anodes. This project will present a material chemistry for dendrite-free and high Coulombic efficiency Li metal anode, finally a theoretical perspective for high-energy-density, high safety, and long lifespan LMBs.

锂金属电池以3~5倍于传统锂离子电池的能量密度有望在下一代储能电池中发挥重要作用，但目前金属锂负极还面临着枝晶生长和体积膨胀问题。金属锂无骨架沉积是其性能恶化的主要因素。碳材料作为一类比表面积大、孔道结构丰富、表面性质易调的负极骨架材料，有望解决金属锂负极的体积膨胀和枝晶生长问题。但目前对金属锂在碳骨架上的形核和生长规律缺乏清晰的认识，阻碍了其在金属锂电池中的应用。.本项目拟开展亲锂性氮掺杂碳骨架中金属锂的形核规律研究，计划通过改变碳材料中氮掺杂的含量、位置、种类以及碳材料的比表面积、孔道结构等表面性质，深入分析锂金属的形核和生长行为与骨架材料表面性质间的构效关系，进而实现金属锂的可控定向沉积。在此基础上实现氮掺杂碳/金属锂复合负极的可控制备，为设计下一代无枝晶生长、高利用率的金属锂负极提供材料基础，为构建高能量密度、高安全性能和长使用寿命的金属锂电池提供理论依据。

金属锂负极作为下一代高比能储能体系的重要电极材料，充满机遇与挑战。金属锂枝晶的生长成为限制金属锂电池实际应用的关键。纳米碳材料作为负极骨架可以有效抑制锂枝晶生长，但现阶段对负极骨架结构设计仍处在尝试阶段，缺乏理论性的指导依据，究其根本原因在于目前对金属锂在这类骨架上的形核和生长规律缺乏清晰的认识。.基于此，本项目以纳米碳骨架材料为载体，实现了不同特征氮掺杂碳材料的可控制备，掌握了其对金属锂形核和生长行为的影响规律，并制备出高性能的氮掺杂碳/金属锂复合负极，最终获得了高能量密度、长循环寿命、高稳定性的金属锂全电池。在此基础上，本项目还探究了其他种类碳材料对金属锂负极的保护作用，开展了金属锂/碳复合负极的大规模可控制备。