One-time sintering process to synthesize ZrO2-coated LiMn2O4 materials for lithium-ion batteries

Herein, different amounts of ZrO2-coated LiMn2O4 materials are successfully prepared by one-time sintering ZrO2-coated Mn3O4 and Li2CO3. Scanning and transmission electron microscopy results confirm that the ZrO2 coating layer on the surface of Mn3O4 can still be maintained on the surface of the final LiMn2O4 particles even after long-term high-temperature heat-treatment. Three key factors to realize ZrO2-coated LiMn2O4 materials via the one-time sintering process are as follows: (i) the Mn3O4 precursor is coated by ZrO2 in advance; (ii) the ionic radius of Zr4+ is much larger than those of Mn3+ and Mn4+; (iii) the pre-calcination temperature is set in the reaction temperature range between Li2CO3 and Mn3O4 and lower than that between Li2CO3 and ZrO2. The 3 wt% ZrO2-coated LiMn2O4 material exhibits excellent electrochemical properties with an initial specific discharge capacity of 118.8 mA h g(-1) and the capacity retention of 90.1% after 400 cycles at 25 degrees C and 88.9% after 150 cycles at 55 degrees C. Compared with the conventional coating method, the one-time sintering process to synthesize ZrO2-coated LiMn2O4 materials is very simple, low-cost, environmentally friendly, and easy to scale up for large-scale industrial production, which also provides a valuable reference for preparing other coating-type cathode materials for lithium-ion batteries.