Synergism between Cationic and Anionic Redox Reactions in Materials with Colossal Intercalation Capacity
The CARiM is designed to advance an entirely new concept for triggering a synergism between cationic and anionic redox reactions in layered sodium transition metal oxides (NaxTMO2) and MOFs with an aim to reach a colossal intercalation capacity. The dual redox reaction breaks the paradigm of the materials for limited number of intercalated ions: instead of compensating the charges of guest ions only by the change in the oxidation state of TM cations of the host material, the boosting of the anion redox activity enables an extra amount of guest ions to be intercalated. The proof-of-concept is built on the development of experimental and theoretical approaches for surface and structural engineering of three layered NaxTMO2 and MOFs. The research plan is broken into four work packages; each of them is dedicated to one of the research objectives. The unlocking of dual redox reactions during Li+/Na+ intercalation will be reached by selective substitution of TM ions in NaxTMO2 with intercalation inactive ions (Mg2+, Ti4+ and Ge4+), followed by creation of metal vacancies inside the layers. The deposition of oxygen-storage materials on NaxTMO2 is a strategy to stabilize the anionic redox reaction by avoiding the side surface reactivity. The covalent and coordination bonding in MOFs assembled from redox active TM and linkers also allows to reach a massive alkali intercalation. Based on DFT in periodic boundary conditions, the predicted redox active MOFs will be experimentally validated. The smart combination of ex-situ and in-situ diffraction and spectroscopic techniques will permit us to get insight into the mechanism of the intercalation reactions and it is this mechanism that is needed to understand the redox chemistry of materials. The most risky part of CARiM is the formulation of new principles for materials with colossal intercalation capacity. The research capacity of the PI and the interdisciplinary research team are capable to tackle these ambitious targets.