Mechanistic Studies of Transition Metal‐Terephthalate Coordination Complexes upon Electrochemical Lithiation and Delithiation

Abstract

Redox‐active organic molecules are intriguing candidates as active electrode materials for next‐generation rechargeable batteries due to their structural diversity, environmental friendliness, and solution‐phase preparation processes. Recently, a transition metal–organic coordination approach is exploited to construct high capacity anodes for lithium‐ion rechargeable batteries. Here, a family of transition metal–organic coordination complexes with terephthalate ligands is synthesized that exhibit reversible capacities above 1100 mA h g−1. The reaction mechanism to describe the multi‐electron redox processes is investigated at the molecular‐level via the synchrotron‐sourced X‐ray absorption spectroscopy and solid‐state NMR analyses. The spectroscopic studies reveal that the electrochemical process involves oxidation state changes of the transition metals followed by additional lithium insertion/extraction in the conjugated aromatic ligands. The combined approaches assisted by synthetic organic chemistry and solid‐state analysis provide mechanistic insights into excessive lithiation processes that have implications for the design of high‐performance anode materials.