NSF-BSF: Role of Heteroatom Doping on Aqueous Electrochemical Ion Insertion in Vanadium Oxides

About This Grant

PART I: NON-TECHNICAL SUMMARY Electrochemical ion insertion into inorganic metal oxide materials is an important mechanism that can enable energy storage, smart window, electronic, and environmental technologies. If the host materials are vanadium oxides, electrochemical insertion of ions can change their structure and properties in ways that are useful for such applications. Doing so from aqueous electrolytes is attractive from the standpoint of safety, sustainability, and scalability. However, vanadium oxides tend to degrade in water, making their use in aqueous systems challenging. This research, with support from the Solid State and Materials Chemistry program in NSF’s Division of Materials Research, takes a new approach to improving the stability of vanadium oxides in water. The research team introduces small amounts of other transition metals into vanadium oxides, using a method known as heteroatom doping. This improves the stability of vanadium oxides in aqueous electrolytes and encourages the desired ion insertion behavior. The project utilizes advanced in-situ electrochemical tools to investigate how the structure and composition of heteroatom-doped vanadium oxides influence their charging mechanism and, consequently, their electrochemical performance. The project brings together researchers from the United States and Israel with complementary expertise and will train students in both countries in state-of-the-art solid-state materials electrochemistry. The knowledge gained from this project could inform the design of next-generation energy, electronic, and environmental technologies, advancing U.S. goals in energy security, scientific innovation, and economic growth. Additionally, this project trains undergraduate and graduate students to work on collaborative, interdisciplinary research team and develops hands-on teaching tools on dynamic property changes through electrochemical ion insertion for undergraduate students in the U.S. and Africa through Prof. Augustyn’s Africa-U.S. collaboration project, SciBridge. PART TWO: TECHNICAL SUMMARY Electrochemical ion insertion is an important mechanism for storing charge and dynamically tuning the optical, electronic, and magnetic properties of vanadium oxides. Doing so from aqueous electrolytes is attractive from the standpoint of safety, sustainability, and scalability. However, vanadium oxides undergo numerous proton-coupled dissolution mechanisms in aqueous electrolytes. With this project, supported by the Solid State and Materials Chemistry program in NSF’s Division of Materials Research, the researchers investigate the role of heteroatom doping of vanadium oxides on electrochemical insertion of divalent cations and the accompanying co-insertion processes of water and/or protons from aqueous electrolytes. The hypothesis is that vanadium oxides can be stabilized to favor divalent cation insertion by doping them with more acidic early transition metals, such as Ti4+, while conversely, proton-coupled vanadium oxide dissolution is favored by doping with more basic, later transition metal cations (e.g., Mn4+). The international research team synthesizes heteroatom-doped hydrous and anhydrous vanadium oxides to understand the aqueous chemistry of the heteroatom-doped vanadium oxides and determine the electrochemical mechanisms using in situ and operando electrochemical methods. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.