Effects of AgNPs-coating on the electrochemical performance of LiMn2O4 cathode material for lithium-ion batteries

The Jahn-Teller effect and severe side reactions with liquid electrolyte have been considered as the main obstacles to the further application of LiMn2O4 electrodes. Herein, Ag nanoparticles (AgNPs) were successfully coated on the surface of LiMn2O4 particles via chemical deposition and pyrolysis methods. The properties, microstructures, and morphologies of LiMn2O4 electrodes were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectrometer, and electrochemical performance tests. The results indicated that the LiMn2O4 coated with AgNPs delivered excellent cycling stability and high-rate capability. Especially when the mass fraction of AgNPs-coating was 8 wt%, the specific discharge capacity of the LMO-8 sample was 127.5 mAh g(-1) at 0.2C rate; the capacity retention rates over 500 and 100 cycles at 0.5 and 1C rate were 90.2% and 95.4%, respectively; and the specific capacity could reach 101.3 mAh g(-1) even at 5C rate. The enhanced electrochemical performance of AgNPs-coated LiMn2O4 can be ascribed to the stabilized surface, high electronic conductivity, and superior kinetic properties. This work demonstrates AgNPs are a kind of coating material suitable for surface modification of LiMn2O4 cathode, and can also be used in the preparation of other types of electrode materials.