Study on the enhanced electrochemical performance of LiMn2O4 cathode material at 55 °C by the nano Ag-coating

• Nano-sized Ag-coated LiMn2O4 particles were prepared through a combustion method.
• The rate performance and cycling property of LiMn2O4 at 55 °C were enhanced by Ag.
• The Ag particles dramatically increased the electronic conductivity of LiMn2O4.
• The dissolution of LiMn2O4 at 55 °C could not be completely inhibited by Ag.
• The dissolution of LiMn2O4 at higher C-rates at 55 °C was weaker.

In this paper, the nano-sized Ag particles were coated on the surfaces of the spinel LiMn2O4 nanoparticles through a one-step combustion method. It was shown that the rate performance and cycling performance of LiMn2O4 could be effectively improved by the appropriate amount of Ag (5 wt%) not only at room temperature (25 °C) but also at high temperature (55 °C). This was because the Ag particles dispersed on the surface of LiMn2O4 had dramatically increased its electronic conductivity. Definitely, the electrochemical performance of the Ag-coated LiMn2O4 particles at 55 °C was not as excellent as that at 25 °C. Besides, the Ag-coated LiMn2O4 displayed much better cycling performance at higher C-rates (2 C and 5 C) at 55 °C, compared with that at lower C-rate (0.5 C). This was because Ag was just dispersed rather than being densely coated on the surface of LiMn2O4, so the dissolution of LiMn2O4 at 55 °C could not be completely inhibited by Ag. Moreover, the dissolution of LiMn2O4 at 2 C and 5 C at 55 °C was much weaker than that at 0.5 C, caused by the faster transformation between Mn3+ and Mn4+. As a result, the electrochemical performance of LiMn2O4 could be enhanced by the Ag-coating at high temperature.