Dawson-Type Polyoxomolybdate Anions (P2 Mo18 O626- ) Captured by Ionic Liquid on Graphene Oxide as High-Capacity Anode Material for Lithium-Ion Batteries

Abstract

The development of advanced anode materials is of significance for the next generation of lithium-ion batteries (LIBs). Herein, imidazolium-based ionic liquids (ILs) are grafted covalently on the surface of graphene oxides (GO) through the carboxyl-amino bond, providing a loading hotbed for the Dawson-type polyoxometalate (POM) of (NH₄ )₆ P₂ Mo₁₈ O₆₂ (denoted as P₂ Mo₁₈ ). The as-prepared GO-IL-P₂ Mo₁₈ nanocomposite is characterized by FTIR and Raman spectroscopy, TGA, SEM, TEM, and XPS. The nanocomposite is used as the anode material for LIBs, and shows a high reversible capacity of 903.9 mAh g^-1 with a long cycle life over 1000 cycles. Galvanostatic cycling tests, CV measurements, and AC impedance spectra reveal that the POMs in the GO-IL-P₂ Mo₁₈ nanocomposite give an enhanced specific capacity during the Lithium insertion/extraction process, and the IL provides a favored contact between the electrolyte and the electrode.

Keywords: anode materials; electrochemistry; graphene oxide; ionic liquids; polyoxometalates.