CAREER: Controlling two-dimensional heterointerface in layered oxides for electrodes with advanced electrochemical properties

非技术描述：该职业项目旨在创造一种具有先进电荷存储能力的全新陶瓷氧化物材料，为具有更高能量密度、更快充电速度和更长的寿命的下一代电池打开大门。这些新材料是二维（2D）氧化物基结构，由氧化物层和导电层交替构成，如石墨烯基化合物或过渡金属碳化物（MXenes）。由此产生的结构表现出对电池电极很重要的特征：允许离子运动的空间，以及能够快速传输电子的导电层。在高质量的层层结构中结合层状金属氧化物和碳基化合物，为发现和研究界面上发生的新现象提供了机会。这一基本认识对于创造具有更高能量和动力能力的电池非常重要。在这项工作中开发的材料和方法与更广泛的应用相关，包括能量存储，电致变色（负责可逆的颜色变化），传感，驱动（或运动控制）和水处理。这个项目的跨学科性质吸引了不同的本科生和研究生来研究。该项目将二维结构的合成和特性整合到PI所在机构的工程课程中，并通过制作关于材料合成和电化学特性的教育视频来丰富外展计划。一个以电化学为主题的游戏“Family Feud”的变体被用来吸引更多的学生进入STEM领域。技术细节：本研究的重点是了解如何在分层材料中创建和控制面对面的异质结构界面。其目标是生产具有高电子和离子输运的二维氧化物异质结构，从而提高锂离子、钠离子和k离子电池的储能能力。层状过渡金属氧化物在插层反应中表现出较高的氧化还原活性和相对较高的工作电位，使其在储能装置中用作阴极特别有吸引力。然而，大多数氧化物的低电子导电性限制了它们的性能。为了克服这一限制，层状氧化物通过可控制地交替不同材料的原子厚度层，以独特的异质结构与导电二维化合物结合在一起。二维异质结构电极采用溶胶-凝胶辅助过渡金属氧化物合成工艺，通过(1)化学预插层有机分子然后热解，或(2)在溶胶-凝胶过程中添加导电相（石墨烯或MXene）的固体纳米片。本工作对层状异质结构材料中离子和电子的输运以及电荷存储机制的进一步理解有望导致更好的电极和开辟令人兴奋的新研究方向。定制的二维异质界面使设计具有可调结构和成分的新型陶瓷材料成为可能，这些材料具有高离子存储能力、快速电子和离子传输以及增强的电化学稳定性。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。

NON-TECHNICAL DESCRIPTION: This CAREER project aims to create a completely new class of ceramic oxide materials with advanced charge storage capabilities, opening a door to next-generation batteries with higher energy density, faster charging and a much longer lifetime. These new materials are two-dimensional (2D) oxide-based structures that are built by alternating oxide layers and electronically conductive layers, such as graphene-based compounds or transition metal carbides (MXenes). The resulting structures exhibit characteristics important for battery electrodes: space that allows ion movement, and conductive layers that enable fast transport of electrons. Combining layered metal oxides and carbon-based compounds in high quality layer-by-layer architecture offers an opportunity to discover and investigate new phenomena occurring at interfaces. This fundamental understanding is important for the creation of batteries with improved energy and power capabilities. The materials and methods developed in this work are relevant to a wider range of applications, including energy storage, electrochromics (responsible for reversible changes of colour), sensing, actuation (or control of movement), and water treatment. The interdisciplinary nature of this project attracts diverse undergraduate and graduate students to research. The project integrates synthesis and properties of 2D structures into the engineering curriculum at the PI's institution and enriches outreach programs through the creation of educational videos on synthesis and electrochemical properties of materials. A variation on the gameshow Family Feud focused on electrochemistry is being used to attract more students to STEM fields.TECHNICAL DETAILS: This research is focused on understanding how face-to-face heterostructured interfaces can be created and controlled in layered materials. The aim is to produce 2D oxide-based heterostructures with high electron and ion transport leading to improved energy storage capabilities in Li-ion, Na-ion and K-ion batteries. Layered transition metal oxides show high redox activity in intercalation reactions and relatively high working potentials, making them especially attractive for use as cathodes in energy storage devices. However, the low electronic conductivity of most oxides limits their performance. To overcome this limitation, layered oxides are combined in unique heterostructured architectures with electronically conductive 2D compounds by controllably alternating atomically thick layers of different individual materials. The 2D heterostructure electrodes are constructed using a sol-gel assisted transition metal oxide synthesis process through (1) chemical pre-intercalation of organic molecules followed by pyrolysis, or (2) addition of solid nanoflakes of conducting phases (graphene or MXene) during the sol-gel process. The improved understanding of the transport of ions and electrons and charge storage mechanisms in layered heterostructured materials achieved in this work is expected to lead to better electrodes and open exciting new research directions. The tailored 2D heterointerfaces make it possible to design new ceramic materials with tunable structures and compositions that exhibit high ion storage capability, rapid electron and ion transport, and enhanced electrochemical stability.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.