Enhanced electrochemical performance of LiMn 2 O 4 by constructing a stable Mn 2+ -rich interface

Abstract Spinel LiMn 2 O 4 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 LiMn 2 O 4 by constructing a stable coating layer. In this work, LiMn 2 O 4 @LiMnPO 4 composite, spherical LiMn 2 O 4 (LMO) as core and Mn 2+ -rich phase of LiMnPO 4 (LMP) as shell, is designed and synthesized. Two composites of LiMn 2 O 4 particles coated with 3 wt% and 10 wt% LiMnPO 4 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% LiMnPO 4 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 LiMn 2 O 4 with 90 mAh g −1 and 45.8 mAh g −1 , respectively. This core-shell structure with Mn 2+ -rich phase as a coating layer effectively enhance the material’s cycling performance and rate capacity by reducing the contact of LiMn 2 O 4 with electrolyte.