A Single-Phase Mixed Ion-Electron Conducting Metal–Organic Framework
(2026) Journal of the American Chemical Society — Vol. 148, n° 4, p. 4339-4348 (2026)
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- Mixed ionic-electronic conductors (MIECs) are highly sought after for electrochemical systems because they support concurrent charge and mass transport. Yet, structurally well-defined single-phase MIECs remain scarce, as most systems rely on physical mixtures of ionic and electronic conductors. Here, we introduce a cation-rich design strategy to realize solid-state mixed Li +-electronic conduction in a two-dimensional copper− catecholate metal−organic framework, Cu 3 (HOTAT) 2 , built from the 3-fold symmetric new ligand 2,3,7,8,12,13-hexahydroxytriaza-truxene (HHTAT). Owing to the combined redox activity of Cu 2+ /Cu + and the HOTAT ligand, controlled fractional reduction generates a family of Li x Cu 3 (HOTAT) 2 (0 ≤ x ≤ 7.50) phases with tunable transport properties, in good agreement with electronic-structure calculations. The Li-rich phase Li 7.50 Cu 3 (HOTAT) 2 exhibits intrinsic mixed conduction at room temperature, with an electronic conductivity of 2.8 × 10 −3 S cm −1 , and solid-state Li + conductivity of 1.1 × 10 −3 S cm −1. As a proof of concept, Li 7.50 Cu 3 (HOTAT) 2 operates as a homogeneous cathode in all-solid-state Li batteries, delivering 100 mAh g −1 after 100 cycles with ∼99.8% Coulombic efficiency, indicative of highly reversible electrochemical behavior. These results establish cation-rich reduction of redox-active 2D MOFs as an efficient route to engineer solid-state mixed Li +-electronic conductors, opening a pathway toward dual-conducting porous materials for solid-state electrochemical technologies.
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Apostol, P., Zhang, Y., Dubois, S., Lin, X., Guo, X., Markowski, R., Wang, J., Shi, W., Caputo, L., Tie, D., Frano, V., Darsi Rambabu, Bakuru, V. R., Robeyns, K., Dincă, M., Ajayan, P., Charlier, J.-C., & Vlad, A. (2026). A Single-Phase Mixed Ion-Electron Conducting Metal–Organic Framework. Journal of the American Chemical Society, 148(4), 4339-4348. https://doi.org/10.1021/jacs.5c18105 (Original work published 2026)