Synthesis, structure and lithium storage performance of a copper–molybdenum complex polymer based on 4,4′-bipyridine

Abstract

A novel bimetal organic complex polymer (MOCP) with the molecular formula C20H16Cu2MoN4O4 (shortened as bpyMoCu2) was prepared by hydrothermal synthesis, and the structure was revealed by single crystal X-ray diffraction. BpyMoCu2 shows one-dimensional (1D) structure that is made up of copper and molybdenum atoms as nodes (the molar ratio Cu:Mo ​= ​2:1) being bonded with 4,4′-bipyridine (4,4′-bipy) ligand as linker. It is worth mentioning that copper is coordinated by three atoms and molybdenum is coordinated by four O atoms, which provide a large number of active sites around them (Cu and Mo). BpyMoCu2 shows a rectangular parallelepiped mesoporous morphology, which is more conductive for lithium ion to transfer at electrode/electrolyte interface. As an anode material of lithium ion batteries (LIBs), bpyMoCu2 shows an ultra-high capacity of 1628.6 ​mAh g-1 for the first cycle at a current density of 100 ​mA g-1, and the capacity could still be maintained at 805.4 ​mAh g-1 after 100 cycles. Besides, bpyMoCu2 shows an excellent rate performance due to the 1D structure and synergistic lithium storage mechanisms.