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

非技术摘要：可再生能源的更大采用需要经济和可扩展的电能存储解决方案。新型电池化学是急需的下一代电能存储技术的关键，以实现可持续发展的社会。传统电池利用阳离子聚焦电池化学，这意味着带正电的离子在电池的充电和放电期间迁移。通过该项目，由材料研究部陶瓷计划支持，俄勒冈州州立大学和范德比尔特大学的研究人员研究了基于阴离子的电池（迁移带负电荷的离子而不是带正电荷的离子）用于网格存储的可能机制。阴离子电池有很大的潜力取代目前的阳离子电池用于可扩展的能量存储，但缺乏基本的机理理解。该项目产生了关于金属氧化物电池材料中的化学环境更适合电池运行期间阴离子的运输和储存的知识。在该项目中，只有可持续的、地球上丰富的元素才被用于电极，包括锰基和铁基氧化物、卤离子和氢氧化物;它们与廉价安全的水性电解质相结合。新的电池化学如果开发成功，将在未来通过提供低成本，环保的储能解决方案大大造福我们的社会。作为该项目的一部分，PI向来自服务不足社区的学生介绍了新型电池化学的最先进材料研究，并通过在线课程等机构工具向公众传播知识。技术摘要：电化学阴离子插入宿主的知识仍然有限，特别是当宿主是金属氧化物时。在金属氧化物中插入阴离子本质上是具有挑战性的，因为金属氧化物内衬有排斥进入的阴离子的氧化物。该项目由材料研究部的陶瓷项目支持，通过改变金属氧化物的局部结构来精确地解决这个问题。俄勒冈州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，即金属氧化物中阳离子的不可逆插入促进了可逆的阴离子储存，形成金属卤氧化物。他们的研究测试了中心假设，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。它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被捕获的阳离子相互作用，并推进了我们对化学环境以及阳离子捕获和阴离子插入所引起的变化的理解。利用电化学和结构表征以及第一性原理预测建模方面的专业知识的协同作用，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械理解，其中捕获的Zn离子增强了氯化物储存。该项目还开发了新机制的一般原理，包括不同的阳离子被捕获，金属氧化物作为主体和阴离子电荷载体。此外，综合实验和计算研究为一个有前途的新研究领域奠定了基础，该领域使用阴离子插入形成金属卤氧化物。该奖项反映了NSF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.