CAS-Climate:Collaborative Research:Understanding How Electrochemical Cation Trapping in Metal Oxides Enhances Subsequent Reversible Insertion of Anions in Forming Metal Oxyhalides

摘要：更多地采用可再生能源需要经济和可扩展的电能存储解决方案。新型电池化学是实现可持续社会所需的下一代电能存储技术的关键。传统电池利用以阳离子为中心的电池化学，这意味着带正电荷的离子在电池充放电过程中迁移。在这个项目中，俄勒冈州立大学和范德比尔特大学的研究人员在材料研究部的陶瓷项目的支持下，研究了阴离子电池（用带负电荷的离子而不是带正电荷的离子迁移）用于电网存储的可能机制。阴离子电池有很大的潜力取代目前的阳离子电池进行可扩展的能量存储，但缺乏基本的机制理解。该项目产生了关于金属氧化物电池材料中哪种化学环境更适合电池运行过程中阴离子的运输和储存的知识。该项目只研究可持续的、地球上丰富的元素，包括锰基和铁基氧化物、卤化物离子和氢氧化物；它们与廉价和安全的水电解质结合在一起。新的电池化学，如果开发成功，将极大地造福我们的社会，通过提供一个低成本，环保的能源存储解决方案在未来。作为该项目的一部分，pi向来自服务欠缺社区的学生介绍最新的新型电池化学材料研究，并通过在线课程等机构工具向公众传播知识。技术摘要：寄主中电化学阴离子插入的知识仍然有限，特别是当寄主是金属氧化物时。阴离子在金属氧化物中的插入本身就是一项挑战，因为在金属氧化物的间隙中，氧化物会排斥进入的阴离子。该项目由材料研究部陶瓷项目支持，通过用捕获阳离子改变金属氧化物的局部结构，精确地解决了这个问题。俄勒冈州立大学和范德比尔特大学的研究人员阐明了一种新的离子插入机制，即阳离子在金属氧化物中的不可逆插入促进了可逆阴离子的储存，从而形成金属氧卤化物。他们的研究验证了一个中心假设，即阳离子捕获改变了金属氧化物的结构和化学环境，从而大大增强了随后的阴离子插入。他们阐明了阳离子捕获如何改变金属氧化物的局部结构以及阴离子如何与捕获的阳离子相互作用，并促进了我们对化学环境以及阳离子捕获和阴离子插入引起的变化的理解。利用电化学和结构表征的专业知识以及第一性原理预测建模的协同作用，研究人员通过研究尖晶石Mn3O4的模型结构，建立了对这种新机制的机理理解，其中捕获的zn离子增强了氯化物的储存。该项目还开发了跨不同阳离子被捕获、金属氧化物作为宿主和阴离子电荷载体的新机制的一般原理。此外，实验与计算相结合的研究为阴离子插入形成金属氧卤化物的新研究领域奠定了基础。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 Abstract: Greater adoption of renewable energy sources necessitates economical and scalable electric-energy storage solutions. Novel battery chemistry holds the key to much-needed next-generation electric energy storage technologies to enable a sustainable society. Conventional batteries utilize cation-focused battery chemistry, which means positively charged ions migrate during the charge and discharge of a battery. With this project, supported by the Ceramics program in the Division of Materials Research, researchers at Oregon State University and Vanderbilt University investigate a possible mechanism for anion-based batteries (with migrating negatively charged ions instead of positively charged ones) for grid storage. Anion batteries have a great potential to replace current cation batteries for scalable energy storage, but fundamental mechanistic understanding is lacking. The project generates knowledge about what chemical environment in the metal-oxide battery material is more suitable for the transport and storage of anions during battery operation. Only sustainable, earth-abundant elements are investigated in the project for the electrodes, including manganese- and iron-based oxides, halide ions, and hydroxide; they are coupled with inexpensive and safe aqueous electrolytes. The new battery chemistry, if developed successfully, will greatly benefit our society by providing a low-cost, environmentally friendly energy-storage solution in the future. As part of the project the PIs introduce state-of-the-art materials research of novel battery chemistry to students from underserved communities and disseminate the knowledge to the public through institutional tools such as an online course.Technical Abstract:The knowledge of electrochemical anion insertion in hosts remains limited, particularly when the hosts are metal oxides. Anion insertion in metal oxides is inherently challenging because the interstitials are lined with oxides that repulse incoming anions. This project, supported by the Ceramics program in the Division of Materials Research, precisely tackles this problem by transforming the local structures of metal oxides with trapped cations. Researchers at Oregon State University and Vanderbilt University elucidate a new ion insertion mechanism whereby the irreversible insertion of cations in metal oxides promotes the reversible anion storage to form metal oxyhalides. Their research tests the central hypothesis that cation trapping transforms the structure of metal oxides and the chemical environment such that the subsequent anion insertion is greatly enhanced. They elucidate how the cation trapping alters the local structures of metal oxides and how the anions interact with the trapped cations and advance our understanding of the chemical environment and the changes caused by cation trapping and the anion insertion. Utilizing the synergy of expertise in electrochemical and structural characterization and first principles predictive modeling, the researchers establish mechanistic understandings of this new mechanism by investigating the model structure of spinel Mn3O4, in which the trapped Zn-ions enhances chloride storage. The project also develops a general principle of the new mechanism across different cations to be trapped, metal oxides as hosts, and anion charge carriers. Additionally, the integrated experimental and computation studies lay the foundation for a promising new research field using anion insertion to form metal oxyhalides.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.