Collaborative Research: Tunable Control of Mixed Ionic and Electronic Conductivity through Ion Irradiation in Electroceramic Materials for Energy Storage System

非技术描述：这项基础研究的目标是显著提高锂离子电池的性能。这些电池是最有前途的能源存储技术之一，对于可再生能源和电动汽车市场的近期增长非常需要。该项目研究了电陶瓷材料（用于电池）如何通过添加杂质或产生其他缺陷来有意改变。对于电极（即阳极和阴极）材料来说，电导率对于高能和大功率锂离子电池至关重要。最近的研究表明，当电极材料含有缺陷时，性能会得到改善，有可能延长电池的能量、功率密度、稳定性、极端条件下的耐受性和日历寿命。该项目专注于探索模型氧化系统，二氧化钛（TiO2），以揭示这些电陶瓷材料中潜在的导电性现象。此外，该项目还与两所参与大学（博伊西州立大学和普渡大学）的教育、多样性和培训活动相结合。例如，这个项目正在实施一个跨机构的本科生研究人员“交流”计划。技术细节：本研究提出了一种独特的利用辐照来剪裁离子/电子导电性的方法，这可能为辐照增强材料的功能开辟新的研究途径，并导致电陶瓷材料在剪裁电化学性能方面取得前所未有的进步。该项目研究了一种假设，即辐射诱导缺陷可以对电陶瓷材料中的混合离子/电子电导率进行可调控制，从而为锂离子电池的应用提供增强的电化学性能。含有外在缺陷（如掺杂）和内在缺陷（如空位、阳离子无序）的电极表现出更好的电化学性能。具体来说，外在缺陷可以提高电子导电性，而内在缺陷可以提高离子导电性。中能量离子辐照产生本征缺陷，而辐照离子则以外征缺陷的形式植入靶材料。因此，理论上可以认为，适当选择辐照离子种类和能量可以调整离子和电子电导率，从而产生更好的电化学性能。这个项目的重点是模型金属氧化物，TiO2（锐钛矿）。用铌离子辐照的样品会产生内在缺陷和外在缺陷，与用氦离子辐照的样品进行比较，氦离子从目标材料扩散，只留下内在缺陷。这一假设正在晶体薄膜上进行测试，这使得对中间能量辐照对金属氧化物的影响的机理理解得以形成。在此基础上，进一步研究了离子辐照对多晶纳米TiO2电极电化学性能的影响。这项研究正在被纳入教学和推广模块，以便在两个参与机构之间进行整合，并通过NanoHUB提供。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: The goal of this foundational study is to significantly improve the performance of lithium ion batteries. These batteries are among the most promising energy storage technologies and are much needed for near-term growth of the renewable energy and electric vehicle markets. This project examines how electroceramic materials (used in batteries) can be intentionally altered by adding impurities or producing other defects. For electrode (i.e., anode and cathode) materials, conductivity is critical for high energy and high-power lithium ion batteries. Recent research demonstrates improved performance when electrode materials contain defects, with the potential to extend battery energy, power density, stability, tolerance in extreme conditions, and calendar life. This project focuses on and explores the model oxide system, titania (TiO2) to shed light on the underlying conductivity phenomena in these electroceramic materials. In addition, this project is coupled to education, diversity, and training activities that are integrated across two participating universities (Boise State and Purdue). For example, this project is implementing a cross-institutional undergraduate researcher 'exchange' program.TECHNICAL DETAILS: This study presents a unique method for tailoring ionic/electronic conductivity using irradiation, which could open new research pathways in irradiation-enhanced materials functionality and lead to an unprecedented advancement in tailoring electrochemical performance in electroceramic materials. The project investigates the hypothesis that irradiation-induced defects can provide tunable control over the mixed ionic/electronic conductivity in electroceramic materials, thus delivering enhanced electrochemical properties for lithium-ion battery applications. Electrodes containing extrinsic (e.g., doping) and intrinsic defects (e.g., vacancies, cation disorder) exhibit improved electrochemical properties. Specifically, extrinsic defects may enhance electronic conductivity, while intrinsic defects may enhance ionic conductivity. Intermediate energy ion irradiation creates intrinsic defects, while the irradiating ion species becomes implanted in the target material as extrinsic defects. Thus, it is theorized that the appropriate selection of the irradiating ion species and energy enables tuning of the ionic and electronic conductivity to produce better electrochemical properties. This project focuses on a model metal oxide, TiO2 (anatase). Specimens irradiated with niobium ions to produce both intrinsic and extrinsic defects, are compared to specimens irradiated with helium ions, which diffuse from the target material and leave behind only intrinsic defects. The hypothesis is being tested on crystalline thin films, which enables a mechanistic understanding of intermediate energy irradiation effects on metal oxides to be formed. Building on these results, research on a polycrystalline nanoarchitectured TiO2 electrode follows to elucidate the ion irradiation effect on the electrochemical properties of the electrode. This research is being incorporated into teaching and outreach modules for integration across the two participating institutions and is being made available via NanoHUB.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.