New Route toward POM[6]Catenane Members for Lithium-Ion Batteries

A new general route was developed for the synthesis of polyoxometalate (POM)-based [6]catenane frameworks. The hydrothermal reaction of 1,2,4-triazole and AgNO3 with the saturated Keggin polyoxoanions [SiW12O40]4–/[PMo12O40]3–/[AsW12O40]3– as a template led to the successful isolation of POM[n]catenane members [Ag(trz)][Ag12(trz)9][HSiW12O40]·2H2O (1), [Ag(trz)][Ag12(trz)9][PMo12O40]·2H2O (2), and [Ag(trz)][Ag12(trz)9][AsW12O40]·2H2O (3). Single crystal X-ray diffraction analysis not only clearly reveals their [6]catenane nature but also discloses their regular three-dimensional infinite polycatenated structure with a self-dual NaCl-type topology. And for the first time, POM[6]catenane (1 and 2) are used as anode materials in lithium-ion batteries, which exhibit promising electrochemical performance with the first discharge capacities of 1182 mAh g–1 for 1 and 1355 mAh g–1 for 2, and stabilized discharge capacity of 330 mAh g–1 for 1 and 520 mAh g–1 for 2 after 100 cycles at the current density of 0.5 A g–1.