Co-induced performance optimization of Fe-based coordination polymers for lithium storage

Abstract

As electrode for lithium ion batteries (LIBs), Coordination polymers (CPs) have exhibited considerable potential. However, due to the unsatisfactory cycling and rate performance, their practical application often encounters obstacles. This work reports Fe-based coordination polymers with improved lithium storage performance induced by cobalt ions for the first time. The introduction of cobalt ions is confirmed to obviously increase the active sites and conductivity for the electrode. When used as anode of LIBs, the unique Fe–Co-BDC pencil-like polyhedron exhibits a large reversible capacity of 1188 mAh g−1 at 100 mA g−1 after 300 cycles and also shows a good cycling life at the large currents. The lithium storage mechanism of Fe–Co-BDC is demonstrated to be associated with carboxylate groups and benzene rings of the organic ligands during lithiation and delithiation based on the ex situ FTIR and XPS spectra.