UNS: Dendrite-Free Storage of Lithium Metal in Porous Graphene Networks

PI：Nikhil Koratka Proposal number：1510828可充电锂离子电池通过存储风能和太阳能等可再生资源产生的电力，或通过使用可再生资源为零排放电动汽车充电，来支持可持续能源系统的发展。锂离子电池的一个基本可靠性问题是在电池内形成锂金属晶须，最终会使电池短路，造成潜在的火灾危险并缩短电池寿命。该项目的目标是开发一种锂离子电池电极，其中含有一种名为多孔石墨烯的碳，旨在抑制这种有害的过程。该项目将寻求对多孔石墨烯上锂金属形成的基本了解，然后利用这些信息设计更高性能、更安全的锂离子电池。与该项目相关的教育活动包括开发用于工程课堂的锂离子电池互动学习模块，以及向当地高中推广纳米技术主题。用于电化学能量存储的锂离子电池的一个基本问题是，最终在阳极外表面电镀锂金属而不是在需要高能量密度存储的阳极内形成锂金属树枝晶。这些微小的突起在反复循环的过程中生长，最终刺穿隔板，触摸阴极，使设备短路。这项研究的总体目标是对微孔石墨烯阳极中锂金属电镀和枝晶形成有一个基本的了解，然后利用这些信息开发微结构多孔石墨烯网络，以抑制树枝晶的形成并将锂金属电镀限制在多孔网络内。为此，研究计划有四个目标。第一个目标是了解石墨烯缺陷在吸引锂离子和启动电镀机理中的作用。第二个目标是调整石墨烯中缺陷的类型和密度，以控制多孔石墨烯网络中的锂金属存储。第三个目标是探索如何利用机械约束和电场调制效应来抑制多孔石墨烯结构中锂树枝晶的形成。最后，在目标4下，将表征锂离子在多孔石墨烯结构中的扩散动力学。结合详细的从头计算和分子动力学模拟，以及X射线光电子能谱(XPS)、电化学阻抗谱(IES)、扫描电子显微镜和透射电子显微镜，将是实现这些目标的工具。在这四个目标下获得的基本理解将用于制造具有微结构多孔石墨烯阳极的锂离子电池，旨在抑制锂金属树枝晶的形成。性能将通过能量密度、功率密度和充放电循环测量进行评估。研究成果将被用于开发一个基于石墨烯的锂离子充电电池电极结构设计的交互式虚拟实验室，用于本科机械系统实验室课程。

PI: Nikhil KoratkarProposal Number: 1510828Rechargeable 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. A fundamental reliability issue with lithium ion batteries is the formation of lithium metal whiskers within the battery that ultimately short out the battery, creating a potential fire hazard and reducing battery life. The goal of this project is develop a lithium ion battery electrode which contains a form of carbon called porous graphene that will be designed to suppress this detrimental process. The project will seek fundamental understanding of lithium metal formation on the porous graphene and then use this information to design a higher performance, and safer, lithium ion battery. The educational activities associated with this project include the development of interactive learning module on lithium ion batteries for engineering classroom use, and outreach on nanotechnology topics to local high schools.A fundamental problem with lithium ion batteries for electrochemical energy storage is the eventual formation of lithium metal dendrites resulting from the plating of lithium metal on the outside surface of the anode, as opposed to within the anode where it is needed for high-energy density storage. These microscopic projections grow upon repeated cycling and ultimately pierce the separator, touch the cathode, and short out the device. The overall goals of the proposed research are to develop a fundamental understanding of lithium metal plating and dendrite formation in microporous graphene anodes, and then to use this information to develop micro-structured porous graphene networks that suppress dendrite formation and confine lithium metal plating within the porous network. Towards this end, the research plan has four objectives. The first objective is to understand the role of graphene defects in attracting lithium ions and initiating the plating mechanism. The second objective is to tune the type and density of defects in graphene in order control lithium metal storage within porous graphene networks. The third objective is to explore how mechanical confinement and electric field modulation effects can be used to suppress the formation of lithium dendrites in porous graphene structures. Finally, under objective 4, the kinetics of lithium ion diffusion though porous graphene structures will be characterized. A combination of detailed Ab initio and molecular dynamics simulations, as well as X-ray photoelectron spectroscopy (XPS), electrochemical impedance spectroscopy (IES), SEM, and TEM, will be the tools used carry out these objectives. Fundamental understanding obtained under these four objectives will be used to fabricate a lithium ion battery with microstructured porous graphene anodes designed to suppress lithium metal dendrite formation. Performance will be assessed through energy density, power density and charge/discharge cycling measurements. The research results will be used to develop an interactive virtual laboratory on the design of graphene based electrode structures for Li-ion rechargeable batteries for use in an undergraduate mechanical systems laboratory course.