A Single-Phase Mixed Ion-Electron Conducting Metal−Organic Framework
imcn | Louvain-la-Neuve
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, Cu3(HOTAT)2, built from the 3-fold symmetric new ligand 2,3,7,8,12,13-hexahydroxytriazatruxene (HHTAT). Owing to the combined redox activity of Cu2+/Cu+ and the HOTAT ligand, controlled fractional reduction generates a family of LixCu3(HOTAT)2 (0 ≤ x ≤ 7.50) phases with tunable transport properties, in good agreement with electronic-structure calculations. The Li-rich phase Li7.50Cu3(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, Li7.50Cu3(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.
Authors : Petru Apostol, Xiaodong Lin, Simon M.-M. Dubois, Yan Zhang, Robert Markowski, Xiaolong Guo, Jiande Wang, Wenjie Shi, Laura Caputo, Da Tie, Viliam Frano, Darsi Rambabu, Vasudeva Rao Bakuru, Koen Robeyns, Mircea Dincă, Pulickel M. Ajayan, Jean-Christophe Charlier, Alexandru Vlad
A Single-Phase Mixed Ion-Electron Conducting Metal−Organic Framework, J. Am. Chem. Soc. 2026, 148, 4339−4348