Insights into the Size Effect of Ag Nanoparticles on the Electrochemical Performance of Ag-Coated LiMn2O4 Cathode Material

Spinel LiMn 2 O 4 with excellent cycling performance and low cost has been regarded as the most promising cathode material for lithium-ion batteries. However, the manganese dissolution and electrolyte decomposition significantly compromise structural stability, thereby hindering large-scale practical implementation. Here, we propose a surface modification strategy to enhance the structural stability of the LiMn 2 O 4 cathode using Ag nanoparticles as coating materials, where the size of the Ag nanoparticles is controlled by adjusting the decomposition temperatures of AgNO 3 to 600, 700, 750, and 800 °C. Combining the detailed structural characterization and performance characterization, we find that surface coating with the largest-sized Ag nanoparticles with 10.02 nm contributes to stabilizing the interface between the cathode materials and electrolyte, reducing the decomposition of electrolyte, and improving ion diffusion kinetics. Consequently, the corresponding Ag/LiMn 2 O 4 heterostructure exhibits outstanding cycle performance, with an initial discharge capacity of 101.6 mAh g -1 and capacity retention of 84.45% after 1000 cycles at 5 C under 25 °C. Our work demonstrates an effective method to improve the structural stability of LiMn 2 O 4 .