Nanostructured Orthorhombic Niobium Oxide as Electrode Material for High-Rate 3D Li-Ion Batteries

Funding Source

Students

2018
Engineering and Applied Sciences

Faculty

Assistant Professor

Project Summary

Conventional store-bought Li-ion batteries are typically made with laminar sheets of cathode, anode, and electrolyte separator laid upon one another, generally considered to be a “2D battery design.” 2D battery designs experience a tradeoff between high energy density and high power density. With thicker sheets of electrode, the battery is able to store more energy at one time (high energy density), but the charge rate of the battery is slow due to the longer ion diffusion paths (low power density). With thinner sheets of electrode, the battery can be charged more quickly (high power density), but the overall capacity of the battery is lower (low energy density). By making a 3D battery, we are able to make the thickness of the electrode layers thin while keeping overall large amounts of electrode material, allowing for both high energy density and high power density.

This summer, I synthesized and tested nanostructured orthorhombic niobium oxide for use as a 3D Li-ion battery electrode. Niobium oxide has been shown to reach high capacity even at fast cycle rates, allowing for even faster charging with little impact on the capacity of the battery, making niobium oxide particularly attractive as an electrode material. I started by synthesizing nanoporous niobium oxide through a delithiation and heat treatment process. Through characterization using X-ray diffraction and scanning electron microscopy, I was able to confirm the sample I had synthesized was indeed nanoporous orthorhombic niobium oxide. Having synthesized the correct material, I needed to perform electrochemical tests to determine if the material could reach electrochemical performances reported in literature. I made electrode slurries using the niobium oxide powder I synthesized, various carbon components to increase conductivity, and a binder. Once the slurries were deposited on copper foil and dried, I made coin cells, using the niobium oxide slurry as the cathode and lithium metal as the anode. These coin cells were tested using cyclic voltammetry.

Working under Dr. Detsi has given me tremendous insight on what I want to do after graduation. Working on such battery technologies and learning about some of the forefront issues on energy has greatly influenced me to look into the energy industry for a career. Further, I was able to learn how to use several advanced laboratory equipment, including the scanning electron microscope, a glove box, and advanced potentiostats/galvanostats. I also had the opportunity to be more involved in safety around the lab and in overall lab management, learning about a lot of the things that go into making research possible. Thank you to CURF, Dr. Detsi, and the Detsi Lab for an amazing summer and for the fantastic opportunity to experience research in college.