Transition-Metal-Free Boride Cathodes

可充电电池的高成本是电动汽车和电网规模储能系统广泛采用的一个问题。目前使用的电极类型，即嵌入阴极，是昂贵的并且具有低能量密度。这就导致了电池价格的上涨。该项目由美国国家科学基金会材料研究部固体与材料化学项目资助，通过利用氧化还原活性阴离子电荷补偿机制，探索了一种设计高能量密度无过渡金属嵌入阴极的新策略。具有共价阴离子骨架的晶体结构类型允许设计用于Na离子和Mg离子电池化学的新阴极。此外，该项目还包括在无机材料合成和表征领域对研究生和本科生进行全面培训;为来自大新奥尔良地区的教师成立了高中科学教师俱乐部。教师俱乐部旨在让教师参与分享有效的教学策略，并就当前的研究课题对教师进行教育。为了提高科学教育的水平，还建立了一个教育设备借阅图书馆，现在可以向许多高中生进行演示，提高他们对科学的兴趣。技术概要：设计具有氧化还原活性阴离子（RAA）电荷补偿机制的阴极材料是一种新的和有吸引力的可能性，用于提高阴极能量密度。新奥尔良大学的研究人员研究了具有共价阴离子网络的过渡金属和无氧化合物，作为具有RAA的阴极的候选者。该项目由NSF材料研究部的固态和材料化学计划资助，通过具有扩展共价阴离子网络的RAA阴极的实验概念验证，为可能的氧化还原活性阴离子阴极提供了新的重要的基本见解。所选硼化物中的强共价硼-硼键在电化学循环期间保持共价硼骨架。密度泛函理论（DFT）计算表明高能量密度和离子导电性的镁离子阴极材料的研究。本论文主要研究了几种硼化物的合成、结构和电化学性能，它们是潜在的钠离子和镁离子阴极材料。软化学方法的利用将可获得的组合物扩展到新化合物。DFT测定的平均电压和体积变化的阳离子脱嵌以及阳离子扩散和离子电导率的活化能进行。此外，该项目还包括在无机材料合成和表征领域对研究生和本科生进行全面培训;为来自大新奥尔良地区的教师成立了高中科学教师俱乐部。教师俱乐部旨在让教师参与分享有效的教学策略，并就当前的研究课题对教师进行教育。以提高科学教育为目标，还设立了教育设备借阅图书馆，现在可以向许多高中生进行演示，并提高他们对科学的兴趣。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 SUMMARY:High cost of rechargeable batteries is a problem for the widespread adoption of electrical vehicles and grid-scale energy storage systems. The type of electrodes currently used, intercalation cathodes, are expensive and have low energy densities. This leads to the high price of batteries. This project, funded by the Solid State and Materials Chemistry program in the Division of Materials Research at NSF, explores a new strategy for the design of transition-metal-free intercalation cathodes with high energy density by utilizing redox active anions charge compensation mechanism. A crystal structure type with covalent anion framework allows designing new cathodes for Na-ion, and Mg-ion battery chemistries. Additionally, the project includes comprehensive training of graduate and undergraduate students in the areas of inorganic materials synthesis and characterization; the High School Science Teachers Club for the teachers from the Greater New Orleans area has been formed. The Teachers Club is designed to involve teachers in sharing effective teaching strategies and to educate the teachers on current research topics. With the goal of improving the science education, an Educational Equipment Lending Library has also been established, and now enables demonstrations which reach many high school students and to increase their interest in science.TECHNICAL SUMMARY:Design of cathode materials with a redox active anions (RAA) charge compensation mechanism is a new and attractive possibility for increasing cathode energy density. The researchers at the University of New Orleans study transition metal and oxygen-free compounds with covalent anionic networks as candidates for cathodes with RAA. This project, funded by the Solid State and Materials Chemistry program in the Division of Materials Research at NSF, provides new and important fundamental insights into possible redox active anions cathodes through experimental proof-of-concept of RAA cathodes with extended covalent anionic networks. The strong covalent boron-boron bonds in the selected borides preserve a covalent boron framework during electrochemical cycling. Density functional theory (DFT) calculations indicate high energy density and ionic conductivity for the Mg-ion cathode material studied. The research focuses on syntheses, structural and electrochemical properties investigations of several borides, which are potential Na-ion, and Mg-ion cathodes. Utilization of soft chemistry approaches extends the accessible compositions to new compounds. DFT determination of average voltages and volume changes on cation deintercalation as well as activation energies of the cation diffusion and ionic conductivities are performed. Additionally, the project includes comprehensive training of graduate and undergraduate students in the areas of inorganic materials synthesis and characterization; the High School Science Teachers Club for the teachers from the Greater New Orleans area has been formed. The Teachers Club is designed to involve teachers in sharing effective teaching strategies and to educate the teachers on current research topics. With the goal of improving the science education, an Educational Equipment Lending Library has also been established, and now enables demonstrations which reach many high school students and to increase their interest in science.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.