Sequencing 4f-2p Gradient Orbital Coupling Within Guanidinium-Based Coordination Nanoplates to Boost Lithium-Ion Conductivity.

Gaining a comprehensive grasp of how the electronic structure of a central metal in coordination polymers (CPs) relates to Li-ion conductivity is crucial yet challenging. Here, we present four novel cationic guanidinium-based coordination nanoplates as solid Li-ion conductors, focusing on strategies to enhance ion-pair dissociation, anion immobilization, and ionic mobility. Our goal is to precisely manipulate the coordination modes at the metal sites through the utilization of two positional isomers. The intentional modification enabled us to precisely adjust the charge density at the metal sites through the manipulation of the sequence of gradient 4f-2p orbital coupling. The experimental and theoretical analyses demonstrate that the energy levels of the 4f-orbital splitting alter in accordance with the sequence of gradient 4f-2p orbital coupling. This adjustment serves to finely adjust the positive charge density at the metal sites, thereby enhancing the ion-pair dissociation trends and bolstering a strong adsorption strength toward anions in order to optimize a maximum Li-ion conductivity value of 3.11 × 10-3 S cm-1 with an activation energy of 0.23 eV. The MD simulation, in conjunction with the RDF plot, illustrates that, among the different interaction sites, the migration of Li-ions along the axial pathway is preferred over the planar pathway.