In Situ Formed Core–Shell LiZn_xMn_2–xO₄@ZnMn₂O₄ as Cathode for Li-Ion Batteries

Abstract

Elemental doping and surface modification are commonly used strategies for improving the electrochemical performance of LiMn2O4, such as the rated capacity and cycling stability. In this study, in situ formed core–shell LiZn x Mn2–x O4@ZnMn2O4 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 LiMn2O4. We demonstrate that part of Zn2+ ions dope into the spinel to form LiZn x Mn2–x O4 in bulk and other Zn2+ ions occupy the 8a sites of the spinel to form the ZnMn2O4 shell on the outermost surface. This in situ formed core–shell LiZn x Mn2–x O4@ZnMn2O4 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 (LiZn0.02Mn1.98O4), 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 LiMn2O4.