CAREER: Cathode Materials for Aluminum Batteries: Understanding Factors Influencing Al Ion Intercalation into MXenes

用于车辆运输和可再生电网存储的先进电池可以改善国内能源安全，但性能差距和成本限制了使用。此外，利用地球上丰富的资源和国内丰富的资源来生产这些新型电池化学物质是可取的。这个CAREER项目将对先进的电池化学和电池组件进行基础研究，这些组件在安全运行的同时具有更高的能量密度和循环性能的潜力。在考虑的选项中，可充电铝电池（Al-batteries）因铝重量轻且储量丰富而具有吸引力。铝具有低可燃性，并且可以很容易地在空气中处理，用于更简单的电池制造技术。此外，铝离子是三价的，这种性质可以潜在地用于更高的能量密度。铝电池的主要技术挑战是寻找能够可逆存储铝离子的正极材料。该项目解决了这一关键问题，提供了一种新的层状和二维（2D）材料的基本特性，称为MXenes，作为铝电池的正极材料。本项目的研究重点是了解影响Al离子插入到几种MXene组合物结构中的动力学和热力学因素。通过该项目获得的基础知识将使设计一个全新的铝电池正极材料家族成为可能。该项目还包括为阿拉巴马州东南部的初高中学生设计的推广和教育活动，以在科学和工程公平竞赛中取得成功。将开发侧重于确定和执行科学博览会项目的教育模块，并通过教师培训讲习班向当地学校传播。此外，该教育计划利用“科学和工程作为艺术”项目，培养本科生和研究生在科学交流和传播科学概念和发现方面的创造力。这个CAREER项目解决了锂离子电池以外的电池化学需求，其预期结果将使铝电池正极材料的合理设计成为可能。本项目有三个研究目标。目的1涉及阐明组成和表面化学对MXenes的电荷转移动力学和Al离子输运性质的作用。M2CTx MXenes（其中M为Ti、V、Cr或Mo， C为碳，Tx为表面官能团O、F或OH）将被合成并用于研究Al离子插层对阴极界面和结构性质的依赖。目的2涉及研究纳米层间水对Al离子插入MXene结构的影响。本研究的主要重点是了解Al离子在纳米层间水的作用下向MXenes迁移的机理，并研究水合阴极材料的结构和电化学稳定性。最后的目标3涉及了解阳离子预插层对MXene阴极性能的影响，并建立通过阳离子诱导组装工艺设计多层和异质层MXene阴极的原则。在这一目标下的研究寻求在设计具有可控层间环境和高效电子和离子传输途径的铝电池正极材料方面取得变革性进展。通过研究每个因素获得的见解将连接到MXenes结构中电荷转移和Al离子输运的内聚图中。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。

Advanced batteries for vehicle transport and renewable electricity grid storage applications could improve domestic energy security but performance gaps and cost limit use. In addition, it is desirable to use earth abundant and domestically plentiful resources for these new battery chemistries. This CAREER project will conduct fundamental research on advanced battery chemistries and battery components that have the potential for greater energy density and cycling performance while operating safely. Among the considered options, rechargeable Aluminum batteries (Al-batteries) are appealing as aluminum is lightweight and abundant. Aluminum has low flammability and and can be easily handled in the air for simpler battery fabrication techniques. Furthermore, Al ions are trivalent, and this property can be potentially harnessed for higher energy density. The main technology challenge of Al-batteries is finding cathode materials that can reversibly store Al ions. This project addresses this crucial problem by providing a fundamental understanding of the properties of a new class of layered and two-dimensional (2D) materials, called MXenes, as cathode materials for Al-batteries. The research efforts in this project are focused on understanding factors that influence the kinetics and thermodynamics of Al ion intercalation into the structure of several MXene compositions. The fundamental knowledge gained through this project will enable the design of an entirely new family of cathode materials for Al-batteries. This project also includes outreach and educational activities that are designed for middle and high school students in Southeastern Alabama to succeed in science and engineering fair competitions. Educational modules focused on defining and performing science fair projects will be developed and disseminated to local schools through teacher training workshops. In addition, the educational plan utilizes "science and engineering as art" projects to foster creativity in science communication and dissemination of scientific concepts and discoveries among undergraduate and graduate students. This CAREER project addresses the need for battery chemistries beyond Li-ion, and its expected outcomes will enable a rational design of cathode materials for Al-batteries. There are three research objectives in the project. Objective 1 involves elucidating the role of composition and surface chemistry on the charge transfer kinetics and Al ion transport properties of MXenes. M2CTx MXenes (where M is Ti, V, Cr, or Mo, C is carbon, and Tx represents surface functional groups O, F, or OH) will be synthesized and used to study the dependence of Al ions intercalation on the interfacial and structural properties of the cathode. Objective 2 involves studying the effects of nanoconfined interlayer water on the intercalation of Al ions into MXene structures. The main focus of research under this objective is to gain a mechanistic understanding of Al ion transport into MXenes with nanoconfined interlayer water and investigate the structural and electrochemical stability of hydrated cathode materials. The final Objective 3 involves understanding the effects of cation pre-intercalation on the properties of MXene cathodes and establishing the principles of designing multilayered and heterolayered MXene cathodes through a cation-induced assembly process. The research under this objective seeks transformative advances in designing aluminum battery cathode materials with controlled interlayer environments and efficient electronic and ionic transport pathways. The insight obtained through studying each factor will be connected into a cohesive picture of charge transfer and Al ion transport in the structure of MXenes.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.