Reversible Energy Storage in Layered Copper-Based Coordination Polymers: Unveiling the Influence of the Ligand's Functional Group on Their Electrochemical Properties

Coordination polymers represent a suitable model for studying redox mechanisms in materials where both metal cations and ligands undergo electrochemical reactions and are capable of proceeding through reversible multielectron-transfer processes with the insertion of cations and anions into their open structures. Designing new coordination polymers for electrochemical energy storage with improved performance relays also on the understanding of their structure-property relationship. Here, we present a family of copper-based coordination polymer with hexafunctionalized benzene ligands forming a kagome-type layered structure, where the influence of the functional groups in their structure and electrochemical properties is investigated. Their chemical and structural properties have been explored by means of powder X-ray diffraction (PXRD) and Fourier-transform infrared and Raman spectroscopies, followed by investigation of their electrochemical performance in Li half-cells by cyclic voltammetry and galvanostatic cycling techniques. Ex situ PXRD, Raman, X-ray photoelectron spectroscopy, and time-of-flight secondary ion mass spectrometry measurements of cycled electrodes have been carried out to provide insights into the redox mechanism of these copper-based coordination polymers as positive electrode materials.