UNS: Three-Dimensional Porous Nanographene for Highly Efficient Energy Storage in Li-Ion Batteries

PI：乌钢提案编号：1511528可充电锂离子电池通过存储风能、太阳能等可再生资源产生的电力，或通过可再生资源充电为零排放电动汽车提供动力，支持可持续能源系统的发展。然而，目前锂离子电池的存储容量、充电时间和功率输出必须提高，才能进一步渗透电动汽车的市场。该项目的目标是重新设计电池的碳电极，以从根本上改善性能。新的碳电极将基于石墨烯，这是一种碳的形式，被排列成一个原子厚的薄片。将开发新的方法，将石墨烯形成三维结构，通过科学原理设计，以提供高容量、快速充电和重复充电时的稳定性。与该项目相关的教育活动包括为三名来自代表不足的工程学群体的本科生进行暑期研究体验，以及对纽约布法罗地区的小学进行亲身实践。纳米结构石墨烯已成为一种潜在的变革性材料，用于替代交通应用中可充电锂离子电池负极中的多孔碳，因为它具有高比表面积和电子传导性的潜力，从而导致更高的容量和更快的充放电速率。然而，在重复的充放电循环下，由于石墨烯片层的重新堆叠，存储容量迅速衰减。为了解决这一问题，并扩大石墨烯在锂离子电池负极中的应用能力，需要新的纳米石墨烯合成方法。这项研究的总体目标是通过原子级自组装和杂原子取代，合理设计稳定的、具有特定结构和电子性质的三维石墨烯负极，从而对锂离子在该负极中的插入和提取过程有一个基本的了解。拟议的研究有三个目标。第一个目标是开发新的可扩展的合成方案，通过Suzuki偶联和共价稳定来制备一系列结构稳定的氮(N)掺杂纳米管，然后通过控制d晶格间距和N掺杂水平来微调最终三维结构的晶格几何和电子性质。材料的性质将通过光致发光、核磁共振和质谱学来表征。第二个目标是利用具有明确分子尺寸、结构和掺杂的纳米分子模型体系，建立锂离子在掺杂纳米分子上的吸附、解吸和扩散动力学的基本理解。为此，将使用高分辨率电子显微镜成像和显微分析技术的现场电化学中子实验来测量锂离子插入/提取反应过程中石墨烯阳极的组成、结构和热力学过程的变化。采用密度泛函理论(DFT)和纳米尺度动力学模拟方法，对掺氮纳米分子筛上的锂反应机理进行了计算研究。第三个目标是设计和合成具有化学和结构性能的结构化三维多孔纳米烯负极材料，旨在优化锂容量、扩散速度和循环稳定性。研究成果还将用于为布法罗大学关于先进能源材料的新课程开发教学材料。

PI: Gang WuProposal Number: 1511528Rechargeable lithium ion batteries support the development of sustainable energy systems by storing electricity generated by renewable resources such as wind and solar energy, or by powering zero-emission electric vehicles charged by electricity from renewable resources. However, the storage capacity, recharging time, and power output from current lithium ion batteries must improve to enable further market penetration for electric vehicles. The goal of this project is to redesign the carbon electrode of the battery to make fundamental improvements in performance. The new carbon electrode will be based on graphene, a form of carbon that is ordered into sheets one atom thick. New methods will be developed to form graphene into a three-dimensional structure designed through scientific principles to provide high capacity, rapid recharge times, and stability during repeated charging. The educational activities associated with this project include summer research experiences for three undergraduate students from under-represented groups in engineering, and hands-on outreach to elementary schools in the Buffalo, New York area.Nanostructured graphene has emerged as a potentially transformative material for replacing porous carbon in the anode of rechargeable lithium ion batteries for transportation applications because it offers the potential for high surface area and electronic conductivity, leading to higher capacity and faster charge/discharge rates. However, under repeated charge/discharge cycles, the storage capacity fades rapidly because the graphene sheets restack. New synthesis approaches for nanographene are needed to address this problem and to extend the capabilities of graphene for use in lithium ion battery anodes. The overall goals of this proposed research are to rationally design stable, three-dimensional graphene anodes of defined structure and electronic properties for lithium ion batteries through atomic level self-assembly and heteroatom substitution, and then develop a fundamental understanding of lithium ion insertion and extraction processes in this anode. The proposed research has three objectives. The first objective is to develop new and scalable synthetic protocols to prepare a series of structurally stable, nitrogen(N)-doped nanographenes with functional linkers via Suzuki coupling and covalent stabilization, and then fine-tune the lattice geometry and electronic properties of the final three-dimensional structure through controlled d-lattice spacing and N-doping level. Material properties will be characterized by photoluminescence, nuclear magnetic resonance, and mass spectroscopies. The second objective is to establish a fundamental understanding of lithium ion adsorption, desorption, and diffusion kinetics on doped nanographene using nanographene model systems of well-defined molecular size, structure, and doping. Towards this end, in situ electrochemical neutron experiments complimented by high-resolution transmission electron microscope imaging and microanalysis techniques will be used to measure changes in composition, structure, and thermodynamic processes of graphene anodes during lithium ion insertion/extraction reactions. The lithium reaction mechanisms on nitrogen-doped nanographene will be investigated computationally by Density Functional Theory (DFT) and nanoscale dynamic simulation. The third objective is to design and synthesize structured three-dimensional porous nanographene anode materials with chemical and structural properties designed to optimize lithium capacity, diffusion rate, and cyclic stability. Research outcomes will also be used to develop instructional materials for a new course on advanced energy materials at the University of Buffalo.