Advanced Electrochemistry of Na-ion Battery Cathodes Through Chemically Controlled Materials Synthesis

Drexel University, Philadelphia PA

Investigators

Abstract

Non-Technical Abstract Intercalation reactions lie at the heart of the operation mechanism of lithium-ion battery, which remains the most used energy storage device for portable electronics and electric cars. Intercalation is usually a reversible process that involves the introduction of a guest species into a host electrode material. The realization that lithium is a limited resource, which potentially can result in a significant increase in the cost of lithium-ion batteries, has shifted research directions towards investigation of alternate intercalation systems, such as sodium-ion batteries. However the larger size and higher weight limits intercalation and diffusion of sodium ions through common electrode materials, compared to lithium ion. This results in significant electrode degradation (thereby resulting in capacity loss after the first cycle and reduced cycle life) and limitations in operation at high current rates. With support from the Solid State and Materials Chemistry program of the Division of Materials Research, this project focuses on addressing these shortcomings through chemical pre-intercalation of the specific types and amounts of inorganic ions. The proposed work has the potential to enable the development of sodium-ion battery cathodes that can be used to replace current lithium-ion batteries, providing sustainable energy storage that is cheaper, reliable, and environmentally friendly, contributing to the development of next-generation energy storage systems for transportation, grid-storage and other renewable energy applications. The project offers an excellent opportunity to engage senior undergraduate and graduate students in masters and doctoral-level research in the field of Materials Science and Engineering and its broader impact on Materials Chemistry and Electrochemistry. The principal investigator plans to integrate the results of this research in the course on materials for energy storage applications. This project enhances the dissemination of knowledge to a broad research community and general public through presentations at National/International conferences, refereed journal publications and demonstrations at science events. Technical Abstract Chemical pre-intercalation is a wet chemistry approach, in which the inorganic ions are inserted into the crystal structure of the electrode material in a solution followed by the formation of a gel and/or sol, or another form of a precipitate, with inorganic ions being 'trapped' in the structure of a solid material. The goal of this proposed research is to test the hypothesis that high capacity, long cycle life and high power can be achieved in Na-ion battery electrodes by introducing specific types and amounts of chemically pre-intercalated ions, which enables materials with high specific capacity, enhanced structural stability and fast ionic diffusion. Vanadium oxide, a material with rich crystal chemistry, structural flexibility and morphological architectures, is chosen as a host structure for chemical pre-intercalation. The project seeks a systematic understanding of synthesis - structure - performance relationships for chemically pre-intercalated vanadium oxide electrodes in Na-ion batteries. Electrochemical properties of the synthesized materials are evaluated by cyclic voltammetry, galvanostatic discharge/charge cycling, rate capability experiments and impedance spectroscopy measurements. The research team plans to determine how changes in the synthesis parameters affect electrochemical performance with the aim to understand fundamental phenomena related to materials chemistry and structure that may lead to larger amount of the stored charge, faster ion and electron transport, and excellent stability during reversible cycling of sodium ions.