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

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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.