A two-dimensional semiconducting Cu(i)-MOF for binder and conductive additive-free supercapattery

Abstract

Two-dimensional (2D) semiconductive metal–organic frameworks (MOFs) have emerged as potential electrode materials for electrochemical energy devices, combining both the merits of a battery and supercapacitor owing to their porous structure containing redox active metal centers. These electrode materials often suffer from poor conductivity and low cyclic stability and often require conductive additives. Herein, we report the synthesis of a CuCN-based semiconducting MOF (CuCN-MOF) formed from the reaction of CuCN with a nitrogen-rich multidentate 2-(1H-1,2,4-triazol-1-yl)pyridine (2TzPy) linker. The ligand with multiple binding sites along with μ₂-C:N and μ₃-C:C:N coordination modes of cyanide forms a 2D structure, which further generates a 3D architecture due to π–π stacking with cyanide and triazole rings of different layers. Due to the presence of redox-active Cu(I) centers, porous structure, and conducting nature, the applicability of materials has been investigated as a binder and conductive additive-free electrode material. The investigation confirms the supercapattery behavior of the material with a specific capacity of 508 C g⁻¹ at 1 A g⁻¹. Further, the symmetric device formed by CuCN-MOF delivers outstanding energy and power densities (^maxE_d = 68.175 W h kg⁻¹, ^maxP_d = 5.54 kW kg⁻¹) with exceptionally high cyclic stability (96.5% up to 10 000 cycles).