Cobalt- and Cadmium-Based Metal–Organic Frameworks as High-Performance Anodes for Sodium Ion Batteries and Lithium Ion Batteries

Two multifunctional metal–organic frameworks (MOFs) with the same coordination mode, [Co(L)(H2O)]n·2nH2O [defined as "Co(L) MOF"] and [Cd(L)(H2O)]n·2nH2O [defined as "Cd(L) MOF"] (L = 5-aminoisophthalic acid) have been fabricated via a simple and versatile scalable solvothermal approach at 85 °C for 24 h. The relationship between the structure of the electrode materials (especially the coordination water and different metal ions) and the electrochemical properties of MOFs have been investigated for the first time. And then the possible electrochemical mechanisms of the electrodes have been studied and proposed. In addition, MOFs/RGO hybrid materials were prepared via ball milling, which demonstrated better electrochemical performances than those of individual Co(L) MOF and Cd(L) MOF. For example, when Co(L) MOF/RGO was applied as anode for sodium ion batteries (SIBs), it retained 206 mA h g–1 after 330 cycles at 500 mA g–1 and 1185 mA h g–1 could be obtained after 50 cycles at 100 mA g–1 for lithium-ion batteries (LIBs). The high-discharge capacity, excellent cyclic stability combined with the facile synthesis procedure enable Co(L) MOF- and Cd(L) MOF-based materials to be prospective anode materials for SIBs and LIBs.