Outstanding lithium storage performance of a copper coordination complex [Cu(DMSO)2]Cl2 as anode material for lithium-ion batteries

Abstract

Copper coordination complexes are widely used as anode materials for lithium-ion batteries (LIBs) owing to their flexible structure and perfect electrochemical properties, nevertheless, their expensive ligands seriously limit their wide industrial applications. In this study, a low-cost copper coordination complex ([Cu(DMSO)₂]Cl₂) is successfully synthesized by coordinating dimethyl sulfoxide (DMSO) with copper chloride dihydrate (CuCl₂·2H₂O) directly at room temperature. Continuous zigzag chains of copper polyhedrons are formed and interconnect with each other via numerous weak hydrogen interactions (Cl⋯H), resulting in a whole three-dimensional structure. This complex is then employed as the anode electrode in LIBs for the first time. Benefiting from the weak but effective interaction of hydrogen interactions, the capacity of [Cu(DMSO)₂]Cl₂ is as high as 1050 mAh·g⁻¹ at 0.1 A·g⁻¹ after 500 cycles, which is considerably larger than that of pure CuCl₂·2H₂O (185 mAh·g⁻¹ at 0.1 A·g⁻¹). Additionally, the [Cu(DMSO)₂]Cl₂ exhibits excellent rate ability and enhances structural stability. With ex-situ X-ray photoelectron spectroscopy (XPS) measurement results, it can infer that the Cu²⁺ not only promotes the lithium storage process of DMSO, but also provides additional capacity for the battery. This strategy of using DMSO-transition metal complexes as anode materials may offer new tactics for developing novel low-cost LIBs with high performances.