Enhanced Structural Integrity and Electrochemical Performance of AlPO 4 -Coated MoO 2 Anode Material for Lithium-Ion Batteries

Abstract

AlPO 4 nanoparticles were synthesized via chemical deposition method and used for the surface modification of MoO 2 to improve its structural stability and electrochemical performance. Structure and surface morphology of pristine and AlPO 4 -coated MoO 2 anode material were characterized by electron microscopy imaging (SEM and TEM) and X-ray diffraction (XRD). AlPO 4 nanoparticles were observed, covering the surface of MoO 2 . Surface analyses show that the synthesized AlPO 4 is amorphous, and the surface modification with AlPO 4 does not result in a distortion of the lattice structure of MoO 2 . The electrochemical properties of pristine and AlPO 4 -coated MoO 2 were characterized in the voltage range of 0.01–2.5 V versus Li/Li + . Cyclic voltammetry studies indicate that the improvement in electrochemical performance of the AlPO 4 -coated anode material was attributed to the stabilization of the lattice structure during lithiation. Galvanostatic charge/discharge and electrochemical impedance spectroscopy (EIS) studies reveal that the AlPO 4 nanoparticle coating improves the rate capability and cycle stability and contributes toward decreasing surface layer and charge-transfer resistances. These results suggest that surface modification with AlPO 4 nanoparticles suppresses the elimination of oxygen vacancies in the lattice structure during cycling, leading to a better rate performance and cycle life.