Structure-Property Engineering of Redox-Active Tetrathiafulvalene- and Bipyridine-Based Metal-Organic Frameworks for...

Redox-active metal-organic frameworks (MOFs) are gaining increasing attention as next-generation electrode materials owing to their tuneable porosity, structural versatility, and ability to host electronically active ligands. Tetrathiafulvalene (TTF) derivatives are an attractive class of π-conjugated redox units for constructing MOFs that exhibit efficient charge transport. In this study, we investigated the structure-property relationships of TTF-based MOFs by employing tetrathiafulvalene-tetrabenzoate (H₄TTFTB) as a multi-electron redox ligand. We first investigated Cd₂(TTFTB) MOF, a representative TTF-MOF with relatively high electronic conductivity, as a cathode material for lithium-ion and sodium-ion batteries. Cd₂(TTFTB) MOF delivers stable cycling and competitive rate capability, particularly in sodium-ion systems, benefiting from its robust framework and intrinsic porosity, which facilitate ion diffusion. To further enhance the charge-storage performance, we introduced bipyridine co-ligands to construct TTF-hybrid-MOF with dual redox centers. The resulting framework exhibits a markedly improved capacity and electronic conductivity through synergistic redox activity. This study demonstrates a molecular-level design strategy for activating multielectron redox centers in conductive MOFs, highlighting TTF-based coordination frameworks as versatile and promising cathodes for rechargeable batteries.