Synthesis, structure and electrochemistry of Ag-modified LiMn 2O 4 cathode materials for lithium-ion batteries

Abstract

Spinel lithium manganese oxide was prepared by sol–gel method and a series of Ag/LiMn 2O 4 composites with different Ag additive contents were prepared by thermal decomposition of AgNO 3 added to the pure LiMn 2O 4 powders. X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive analysis of X-ray (EDAX) and various electrochemical measurement methods were used to examine the structural and electrochemical characteristics of the Ag/LiMn 2O 4 composite powders. Phase analysis showed that Ag particles were dispersed on the surface of LiMn 2O 4 instead of entering the spinel structure. According to the electrochemical tests results, it is clearly to see that Ag additives efficiently improved the cycling stability, reversibility and high-rate discharge capacity of pristine LiMn 2O 4 by increasing the electrical conductivity between LiMn 2O 4 particles, decreasing the polarization of cathode and reducing the dissolution of Mn. Meanwhile the influence of the Ag additive contents on the electrochemical properties of the Ag/LiMn 2O 4 composites is also investigated in detail.