Transition-Metal-Free Boride Cathodes

非技术综述：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，插层阴极，价格昂贵，能量密度低。这导致电池价格居高不下。该项目由美国国家科学基金会材料研究部固态和材料化学项目资助，探索了一种利用氧化还原活性阴离子电荷补偿机制设计高能量密度无过渡金属插层阴极的新策略。具有共价阴离子骨架的晶体结构类型允许为钠离子和镁离子电池化学物质设计新的阴极。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综合培训；为来自大新奥尔良地区的教师设立了高中科学教师俱乐部。教师俱乐部的目的是让教师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。为了促进科学教育，还建立了教育设备借阅图书馆，现在可以向许多高中生提供演示，增加他们对科学的兴趣。技术摘要：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提高阴极能量密度的一种新的、有吸引力的可能性。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RAA阴极的候选者。该项目由美国国家科学基金会材料研究部的固态和材料化学计划资助，通过扩展共价阴离子网络的RAA阴极的概念实验验证，为可能的氧化还原活性阴离子阴极提供了新的和重要的基本见解。所选择的硼化物中的强共价硼-硼键在电化学循环中保持了共价硼的骨架。密度泛函理论(DFT)计算表明，所研究的镁离子正极材料具有较高的能量密度和离子电导率。本论文主要研究了几种潜在的钠离子和镁离子正极化合物的合成、结构和电化学性质。软化学方法的应用将可及组合物扩展到新化合物。用密度泛函方法测定了阳离子脱嵌的平均电压和体积变化，以及阳离子扩散和离子电导的活化能。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综合培训；为来自大新奥尔良地区的教师设立了高中科学教师俱乐部。教师俱乐部的目的是让教师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。为了改善科学教育，还建立了教育设备借阅图书馆，现在可以向许多高中生提供演示，增加他们对科学的兴趣。该奖项反映了NSF的法定使命，并通过使用基金会的智力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.