In Situ Formed Core-Shell LiZn x Mn 2- x O 4 @ZnMn 2 O 4 as Cathode for Li-Ion Batteries.

Elemental doping and surface modification are commonly used strategies for improving the electrochemical performance of LiMn 2 O 4 , such as the rated capacity and cycling stability. In this study, in situ formed core-shell LiZn x Mn 2- x O 4 @ZnMn 2 O 4 cathodes are prepared by tuning the Zn-doping content. Through comprehensive microstructural analyses by the spherical aberration-corrected scanning transmission microscopy (Cs-STEM) technique, we shed light on the correlation between the microstructural configuration and the electrochemical performance of Zn-doped LiMn 2 O 4 . We demonstrate that part of Zn 2+ ions dope into the spinel to form LiZn x Mn 2- x O 4 in bulk and other Zn 2+ ions occupy the 8a sites of the spinel to form the ZnMn 2 O 4 shell on the outermost surface. This in situ formed core-shell LiZn x Mn 2- x O 4 @ZnMn 2 O 4 contributes to better structural stabilization, presenting a superior capacity retention ratio of 95.8% after 700 cycles at 5 C at 25 °C for the optimized sample (LiZn 0.02 Mn 1.98 O 4 ), with an initial value of 80 mAh g -1 . Our investigations not only provide an effective way toward high-performance LIBs but also shed light on the fundamental interplay between the microstructural configuration and the electrochemical performance of Zn-doped spinel LiMn 2 O 4 .