Synthesis, structure and electrochemistry of Ag-modified LiMn2O4 cathode materials for lithium-ion batteries

Spinel lithium manganese oxide was prepared by sol–gel method and a series of Ag/LiMn2O4 composites with different Ag additive contents were prepared by thermal decomposition of AgNO3 added to the pure LiMn2O4 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/LiMn2O4 composite powders. Phase analysis showed that Ag particles were dispersed on the surface of LiMn2O4 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 LiMn2O4 by increasing the electrical conductivity between LiMn2O4 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/LiMn2O4 composites is also investigated in detail.