Collaborative Research: Engineering the Chemistry at Solid-Solid Interfaces of Li-O2 Battery Cathodes

锂氧电池的储能能力有可能与汽油燃料相媲美，但在这项技术商业化之前，还有很多基础科学知识需要了解。特别是，在电池运行过程中形成的一些化学产物会慢慢降解并毒害材料，导致长时间运行的性能损失。这个研究项目试图通过探索一种廉价的混合金属氧化物电催化剂来克服这些问题，这种催化剂可能会改变锂氧电池的化学性质。该项目旨在开发一个框架来设计锂氧电池的化学结构，并提高其性能，锂氧电池是潜在的下一代储能设备。这些研究结合了先进的表征方法和理论计算，以确定氧化物表面的特性如何影响锂氧电极上产生的产品。这些见解将用于开发设计原则，以帮助识别氧化物电催化剂，提高电池性能。参与该项目的研究人员将与当地K-12学校合作，通过暑期实习和学生交换，让经济困难的学生参与拟议的研究。他们的目标是激励学生从事科学和工程方面的职业。对发生在固-固界面上的反应的基本理解对于下一代能量存储设备（如锂氧电池）的发展至关重要。近年来，锂氧电池因其极高的理论能量密度而引起了人们的极大兴趣。即使达到15%的能量密度，也将相当于汽油的价值，这使得每次充电行驶500英里的锂氧电池在商业上可行。虽然这项技术非常有吸引力，但在广泛采用之前还需要克服许多技术挑战。其中一些挑战包括：(i)固体放电反应产物的不溶解性，导致阴极堵塞，最终导致电池死亡；（ii）低往返（充放电循环）效率由于高电荷过电位解离主要的放电反应产物，过氧化锂；(3)电解质在高过电位下的不稳定性。本研究项目旨在通过设计锂氧电池正极的固体-固体界面来缓解这些问题，这种界面可以选择性地稳定不绝缘的锂缺乏放电产物，并且可以在合理的过电位下解离。研究人员将采用实验和理论相结合的方法来研究这些固体-固体界面的化学性质，目的是设计出可以选择性地调整放电产物分布的材料，从而提高电池性能。特别是，这项工作将涉及高级表征研究和理论计算的结合，以确定元素组成、电子性质和氧化物表面的对称性如何影响锂氧阴极中的放电产物分布。这些研究将阐明整体氧化物晶体结构对放电产物形成的影响，并导致确定氧化物电催化剂的设计原则的发展，这些电催化剂对形成缺锂氧化物放电产物具有高度选择性，因此具有低电荷过电位。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。

Lithium-oxygen batteries potentially could have energy storage capacities that rival gasoline fuel, but there remains much fundamental scientific knowledge to learn about these batteries before the technology can be commercialized. In particular, some of the chemical products formed during the operation of the batteries can slowly degrade and poison the materials, leading to performance losses over extended periods of operation. This research project seeks to overcome these problems by exploring a class of inexpensive, mixed metal oxide electrocatalysts that may alter the chemistry of lithium-oxygen batteries. This project aims to develop a framework to engineer the chemistry of lithium-oxygen batteries, which are a potential next-generation energy storage device, and to improve their performance. The studies combine advanced characterization methods and theoretical calculations to determine how the properties of the oxide surfaces influence the products that are produced on lithium-oxygen electrodes. These insights will be leveraged to develop design principles that will aide in identifying oxide electrocatalysts that improve battery cell performance. The researchers involved in this project will partner with local K-12 schools to involve economically disadvantaged students with the proposed research through summer internships and student exchanges. They aim to inspire the students to pursue careers in science and engineering. A fundamental understanding of the reactions occurring at solid-solid interfaces is critical for the development of next-generation energy storage devices, such as lithium-oxygen batteries. Lithium-oxygen batteries have attracted significant interest in recent years due to their exceptionally high theoretical energy density. If even 15% of this energy density is achieved, then it would equal the value of gasoline, making lithium-oxygen batteries with driving ranges of up to 500 miles per charge commercially viable. While this technology is very attractive, numerous technical challenges need to be overcome before its widespread adoption is possible. Some of these challenges include: (i) insolubility of the solid discharge reaction products, leading to clogging of the cathode and eventually resulting battery cell death; (ii) low roundtrip (discharge-charge cycle) efficiency due to high charge overpotentials to dissociate the main discharge reaction product, lithium peroxide; and (iii) instability of electrolytes at high overpotentials. This research project seeks to alleviate these issues by designing solid-solid interfaces at the cathode of lithium-oxygen batteries that selectively stabilize lithium-deficient discharge products that are not insulating and can be dissociated at reasonable overpotentials. The researchers will apply a combined experimental and theoretical approach to study the chemistry at these solid-solid interfaces with the aim of designing materials that can selectivity tune the discharge product distribution such that it leads to improved battery performance. In particular, the work will involve a combination of advanced characterization studies and theoretical calculations to determine how the elemental composition, electronic properties, and symmetry of the oxide surface influence the discharge product distribution in lithium-oxygen cathodes. The studies will elucidate the effect of the global oxide crystal structure on the discharge product formation and lead to the development of design principles for identifying oxide electrocatalysts that are highly selective towards the formation of lithium-deficient oxide discharge products and therefore exhibit low charge overpotentials.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.