In situ formed Ag nanoparticle decorated LiMn2O4 cathodes with outstanding electrochemical performance

Abstract

Surface coating is an effective approach for realizing the commercialization of cathode materials. Nowadays, ionically conducting surface coatings are commonly used to improve the electrochemical stability of LiMn₂O₄. In this work, LiMn₂O₄ cathodes decorated with in situ formed Ag nanoparticles with high electronic and ionic conductivity are prepared via a simple calcination process. The detailed microstructural mechanism of the influence of Ag on the electrochemical performance enhancement of spinel LiMn₂O₄ is uncovered by spherical-aberration-corrected (Cs-corrected) scanning transmission electron microscopy (STEM). The results demonstrate that the Ag coating helps to promote the transport of Li⁺ and strengthen the cycling stability by alleviating the decomposition of the electrolyte and manganese dissolution. Accordingly, the capacity retention rate of the optimized 5 wt% Ag/LiMn₂O₄ sample reached 80% after 900 cycles with an initial discharge-specific capacity of 100 mA h g⁻¹ at 5 C (1 C = 148 mA h g⁻¹). This work indicates that Ag coating is a promising technology for producing high-energy density lithium-ion batteries.