UNS: Improving Energy Density of Layered Vanadium Pentoxide Nanostructure for Aqueous Electrochemical Energy Storage

Teng，1511014采用可再生的非碳排放能源有可能减少对石油的依赖，并显著减少温室气体排放。可再生的太阳能和风能通常有峰期和非峰期的负荷变化。为了提供清洁和高效的能源解决方案，电化学储能(EES)装置的开发可以加速可再生能源的采用。因此，在非高峰时段产生的电力可以被有效和经济地储存起来，以供在高峰需求时使用。这类设备需要具有较高的能量密度(定义为单位体积或质量在给定系统或空间区域中存储的能量)才能在经济上可行。电化学反应释放出这种材料中的能量。PI计划开发具有足够高能量密度的电化学电容器(ECs)，通常称为超级电容器。智能优点：提高ECs能量密度的方法包括设计层状纳米材料以缩短离子传输的扩散距离，以及利用一价和二价电荷载流子(例如Na+和Mg2+)代替锂离子来增加EES的离子电导和存储容量。该项目将研究五氧化二钒(V2O5)和银掺杂V2O5(Agx-V2O5；X：0.1、0.5和1)层状纳米结构作为电极材料在各种含有一价和二价阳离子(如Na+和Mg2+)的水溶液中的电荷储存机理。材料合成、结构和功能表征以及原位/非原位同步加速器/中子测量获得的结果将使人们从根本上了解影响V2O5和Agx-V2O5纳米层中Na+和Mg2+存储的因素，并帮助设计具有定制厚度和面间距离的新型层状纳米结构，以在保持EC器件高功率性能的同时提高能量存储能力。这些假设是：(I)Ag掺杂将改善V2O5的电导率；(Ii)V2O5和Agx-V2O5纳米层的厚度和晶面间距有利于离子的传输；(Iii)Na+和Mg2+离子在水中的离子电导率高于Li+。特别是，二价镁离子将通过在相同离子输运的情况下带来更多的电荷转移来进一步提高EES器件的电容。为了验证假设，PI将：(I)合成和表征成分、厚度和晶面间距可控的V2O5和Agx-V2O5层状纳米材料；(Ii)在半电池和纽扣电池中进行电化学测量和电动研究。广泛的影响：拟议的研究成功可能导致一种新型的ECS，它可以超越电池和静电电容器，并可能有利地影响能源领域。该项目将通过既定的合作和暑期研究项目，整合致力于在本国机构和国家实验室对学生进行跨学科培训的教育项目。拟议研究的教育目标是在国内研究所建立一个研究平台，培训研究生和本科生以及高中教师进行能源研究的基础研究，并为高中科学和工程教育开发开放的教材。PI将指导高中化学教师在Pi？S实验室参加为期三周的暑期研究，以便将基于暑期研究的优质教学材料结合起来，加强STEM课程和教育。

Teng, 1511014Adoption of renewable non-carbon-emitting energy offers the potential to reduce dependence on petroleum and significantly reduce greenhouse gas emissions. Renewable sun and wind energy sources generally have on-peak and off-peak load variations. To provide clean and efficient energy solutions, the development of electrochemical energy storage (EES) devices can accelerate the adoption of renewable energy generation sources. Thus, electricity generated during off-peak hours can be stored efficiently and economically for use during peak demand. Such devices need to have high energy density (defined as the amount of energy stored in a given system or region of space per unit volume or mass) to be economically viable. Electrochemical reactions release the energy in such materials. The PI plans to develop electrochemical capacitors (ECs), often called supercapacitors, with high enough energy density to be used as EES devices.Intellectual Merit: Means to increase the energy density of ECs include the design of layered nanomaterials to shorten diffusion distance of ionic transport, and the utilization of mono- and bi-valence charge carriers (e.g., Na+ and Mg2+) for EES instead of lithium-ion to increase the ionic conductance and storage capacity. The proposed project will investigate the charge-storage mechanism of vanadium pentoxide (V2O5) and silver doped V2O5 (Agx-V2O5; X: 0.1, 0.5 and 1) layered nano structures as electrode materials for (ECs) in various aqueous electrolytes containing mono- and bi-valence cations such as Na+ and Mg2+. Results obtained from material syntheses, structural and functional characterizations, and in situ/ex situ synchrotron/neutron measurements will provide fundamental understanding of the factors that influence of Na+ and Mg2+ storage inside the V2O5 and Agx-V2O5 nanolayers, and help design new types of layered nanostructures with tailored thickness and interplanar distance to enhance energy storage capacity while retaining high power performance in an EC device. The hypotheses are: (i) Ag dopant will improve the electrical conductivity of V2O5; (ii) tailored thickness and interplanar distance of V2O5 and Agx-V2O5 nanolayers will facilitate ionic transport; (iii) Na+ and Mg2+ ions have higher ionic conductivity in water than Li+. Particularly, bi-valence Mg2+ will further improve the capacitance of the EES devices by bringing more charge transfer upon same amount of ionic transport. To validate the hypotheses, the PI will: (i) synthesize and characterize V2O5 and Agx-V2O5 layered nano materials with controlled composition, thickness and interplanar distance; and (ii) perform the electrochemical measurements and electro-kinetic studies in half-cells and button-cells.Broader Impact: Success with the proposed research could result in a new type of ECs that could outshine batteries and electrostatic capacitors, and could favorably impact the energy sector. The project will integrate educational programs dedicated to the cross-disciplinary training of students at their home institution and national laboratories via established collaborations and summer research programs. The educational goals of the proposed research are to create a research platform at the home institute for training graduate and undergraduate students as well as high school teachers on the fundamental study of energy research, and to developlearning materials for high school science and engineering education. The PI will mentor high school chemistry teachers to participate in three-week summer research in the PI?s lab, so that quality instructional materials based on the summer research can be combined to enhance STEM curriculum and education.