Three-Dimensional π-d Conjugated Coordination Polymer Enabling Ultra-Long Life Magnesium-Ion Storage.

There has been increasing interests in π-d conjugated coordination polymers (CCPs) for energy storage because of their rapid charge transfer through long-range planar π-d conjugation between ligands and metal centers. Nevertheless, currently reported CCPs for energy storage are mostly based on one-dimensional (1D) or two-dimensional (2D) structures. There are few three-dimensional (3D) CCPs reported to date because of the great challenge in constructing non-planar coordination geometries, let alone their applications in multivalent ions storage. Herein, we successfully synthesize a triphenylene-catecholate-based 3D CCP (Mn-HHTP) assembled from the multidentate chelating groups of hexahydroxytriphenylene (HHTP) ligands and their isotropic coordination with Mn 2+ ions. The 3D conjugated structure of Mn-HHTP enables an exceptional cycle life of >4,000 cycles at 0.5 A g -1 for multivalent Mg 2+ ion storage, which is far superior to most organic and inorganic electrode materials. Experimental characterizations combined with theoretical calculations indicate that the semiquinone radicals at the HHTP ligands are the electroactive centers for Mg 2+ ions storage. The excellent performance of Mn-HHTP opens a new avenue towards the design of 3D CCPs for long-life rechargeable magnesium-ion batteries. This article is protected by copyright. All rights reserved.