Enhanced electrochemical performance of LiMn2O4 by constructing a stable Mn2+-rich interface

Spinel LiMn2O4 has drawn continuous attentions due to its low cost, good electrochemical performance, environmental friendliness and natural abundant resources. In view of its severe capacity fading, some types of manganese-based compounds with different Mn oxidation states are selected to protect bare LiMn2O4 by constructing a stable coating layer. In this work, LiMn2O4@LiMnPO4 composite, spherical LiMn2O4 (LMO) as core and Mn2+-rich phase of LiMnPO4 (LMP) as shell, is designed and synthesized. Two composites of LiMn2O4 particles coated with 3 wt% and 10 wt% LiMnPO4 have been compared studied. After 100 cycles at 0.5C rate, the two samples deliver capacity retentions of 96.63% and 93.23% of their initial capacities. Moreover, LMO coated by 3 wt% LiMnPO4 delivers 100.3 mAh g−1 after 200 cycles at 10C rate and 76.3 mAh g−1 after 1000 cycles at 20C rate, much higher than bare LiMn2O4 with 90 mAh g−1 and 45.8 mAh g−1, respectively. This core-shell structure with Mn2+-rich phase as a coating layer effectively enhance the material's cycling performance and rate capacity by reducing the contact of LiMn2O4 with electrolyte.