RII Track 4: Isolating the Role of Metal Centers in the Capacitive Behavior of Porous Framework Electrodes

电极存在于我们的许多口袋和公文包中（例如，在锂离子电池的两极）。它们通常基于导电材料，如石墨，具有“存储”或吸收大量离子（例如锂离子）的设计特性，这些离子位于构成其结构的紧密间隔的原子行之间的致密体中。最近，研究表明，这些离子的超快传输（导致储能装置的快速充放电）可以在具有内置分子通道或称为金属有机框架（mof）的孔的新型材料中实现，如果它们具有适当的导电性-这是材料化学家设计的一项重要任务。我们的项目旨在将这种导电mof与蒙大拿州合成的一类无金属碳框架进行比较，这种框架被称为沸石模板碳（ztc），它在石墨（无孔碳）和mof（多孔含金属材料）之间提供了逻辑上的中间地带。这种比较可以用来分离mof结构中存在的金属原子的作用，以确定它们是否以及如何在多孔框架电极的快速离子储存中发挥作用。蒙大拿州立大学（MSU）的Stadie研究小组和麻省理工学院（MIT）的dincei研究小组将开展合作，旨在弥合mof和ztc之间的科学差距。这两类具有自底向上可设计结构和化学性质的开放多孔框架固体，都已应用于电容储能设备，如超级电容器和混合电池，但对其电化学性能的研究一直脱节。尽管ztc具有优异的储能性能，但缺乏晶体结构或现实的原子模型阻碍了其基础研究。另一方面，人们对mof中的电荷传输、离子迁移率和电容能量存储有了更多的了解，但到目前为止，这些材料的应用前景还不如多孔碳。迫切需要一种基于原子物理化学观点的通用语言和一套度量标准，以有效地结合从每个研究机构获得的见解。我们的计划是将新开发的、真实的结构模型和几个原始ztc样品带到dinczi实验室，对多孔框架固体的电导率和相关电化学性能进行实验和理论结合研究。这项工作的主要目标将是确定无金属碳ztc框架内电荷传输的机制，并随后定制具有高导电性和离子存储容量的新型mof和ztc。这些研究将为下一代储能应用的电容电极材料的合理设计提供新的见解。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Electrodes exist in many of our pockets and briefcases (e.g., at either pole of a lithium-ion battery). These are typically based on a conductive material like graphite that has the designed property of “storing” or absorbing a large number of ions (e.g., lithium ions) in the dense bulk “in between” the tightly spaced rows of atoms that make up its structure. Recently, it has been shown that ultrafast transport of these ions (leading to rapid charging and discharging of the energy storage device) can be achieved in novel materials with built-in molecular channels or pores referred to as metal-organic frameworks (MOFs), if they are suitably conductive - a nontrivial task for the materials chemist to design. Our project aims to compare such conductive MOFs with a class of metal-free carbon frameworks synthesized in Montana, known as zeolite-templated carbons (ZTCs), providing a logical middle ground between graphite (nonporous carbon) and MOFs (porous, metal-containing materials). This comparison can be used to isolate the role of the metal atoms present in the MOFs’ structures, in order to determine whether and how they play a role in rapid ion storage in porous framework electrodes.A collaborative effort will be forged between the Stadie Research Group at Montana State University (MSU) and the Dincă Research Group at the Massachusetts Institute of Technology (MIT) aimed at bridging the scientific gap between MOFs and ZTCs. These two classes of open, porous framework solids of bottom-up designable structure and chemistry, have both been deployed in capacitive energy storage devices such as supercapacitors and hybrid batteries, but investigations of their electrochemical properties have been disjointed. The lack of crystalline structure or a realistic atomistic model have hindered fundamental studies of ZTCs despite their excellent energy storage properties. On the other hand, more is known about charge transport, ion mobility, and capacitive energy storage in MOFs, but these materials have so far fallen short of porous carbons in their promise for applications. A common language and set of metrics founded on an atomistic physical chemical perspective are direly needed to effectively combine the insights gained from each body of research. Our plan is to bring newly developed, realistic structural models and several samples of pristine ZTCs to the Dincă laboratory to carry out combined experimental and theoretical investigations of electrical conductivity and related electrochemical properties of porous framework solids. A primary goal of this work will be to ascertain the mechanism of charge transport within the metal-free carbon framework of ZTCs, and subsequently tailor new MOFs and ZTCs with both high electrical conductivity and ion storage capacity. These studies will shed new insight into the rational design of capacitive electrode materials for next-generation energy storage applications.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.