Using Electrodeposition to Understand the Effects of Composition and Element Segregation on the Physical Properties of Anodes for High Energy-Density Rechargeable Batteries

Colorado State University, Fort Collins CO

Investigators

Abstract

PART 1:  NON-TECHNICAL SUMMARY Energy conversion and storage technology is critical to the operation, maintenance, and development of modern society. The United States now produces over 25 terawatt hours of electricity per year, with the vast majority being provided by non-renewable fuels such as coal, natural gas, and oil. Developing new technologies that are more efficient than existing ones, or technologies that help existing technologies use energy more efficiently, is therefore critical to our future. Over the last few decades, it has become clear that energy storage devices are a key component in a wide range of proposed technologies. The technical requirements vary dramatically based on the specific constraints of each desired application, and as such there is need for a wide range of functional materials, chemistries, and architectures that can be used to build targeted and specific energy storage devices. The research, funded by the Solid State and Materials Chemistry program, focuses on developing non-toxic, inexpensive manufacturing methods for three potential anode materials that could be used in lithium and sodium rechargeable batteries. These materials are known, but how they degrade (and why) is not. Understanding how these materials work and what their key limitations are is the main goal of this study. This is the critical first step toward finding out how to extend the life of these materials and thereby the life of batteries. This Solid State and Materials Chemistry award furthermore enables the principle investigator to conduct outreach activities related to her research involving students at all grade levels as well as the general public and policymakers. For example, the CSU 'Chemistry Club' engages elementary school students, high school students are mentored by the principle investigator and her students in the research lab, the principle investigator gives invited talks about science at local clubs, and she is a board member of the Colorado Clean Energy Cluster, which impacts policy in Colorado directly. PART 2:  TECHNICAL SUMMARY Battery materials that store large amounts of lithium and operate reversibly at the extreme ends of the electrochemical potential range of electrolytes enable high voltage and high energy density battery cells. Among available candidates, elemental alloying materials such antimony and related antimonides possess exceptionally high volumetric capacities and operate at potentials close to the plating of lithium metal, allowing for high theoretical energy density. Nevertheless, they suffer from low reversibility as a result of large changes in their volume during cycling, and poor surface passivation that causes significant degradation of the electrolyte at the anode surface and a subsequent rise in the cell impedance. This work develops direct electrodeposition methods for producing low-cost, high-performance anodes for alkali metal ion (lithium and sodium) rechargeable batteries. The advantage of using electrodeposition is that the composition and morphology of the material can be controlled, and inactive binders are completely eliminated (which greatly aides in the characterization of the functional materials). The research endeavor involves a strategy of synthesizing directly electrodeposited thin films and nanostructures of three key antimonides (nickel, copper, and zinc and animonide) and characterizing them fully to develop a deeper understanding of the lithiation and delithiation reactions that occur as a function of composition, and how these reactions may lead to degradation and ultimately cell failure. Observing the phase formation and elemental composition across films during cycling further aids in the development of a clear model of how these materials work, how they degrade, and ultimately, the development of hypotheses for how to extend cycle life and utility. With this grant the principle investigator also conducts a variety of educational and outreach activities. Besides engaging students at all grade levels in STEM-related activities, she also communicates her findings directly to the general public through invited talks about science at local clubs and as a board member of the Colorado Clean Energy Cluster, which serves to impact policy in Colorado related to the economic development of clean tech companies.