Synergistic effects of zinc-doping and nano-rod morphology on enhancing the electrochemical properties of spinel Li-Mn-O material

Abstract In this work, the zinc-doping and nano-rod morphology are used jointly to enhance the electrochemical properties of LiMn2O4 for the first time. The Zn-doped LiMn2O4 nanorods have been prepared by solid-state lithiation process with zinc nitrate and γ-MnOOH nanorods as zinc dopant, manganese precursor and template, respectively. XRD results indicate that the zinc-doping has no fundamental effect on the phase structure of LiMn2O4. All the obtained samples (LiMn2O4 nanorods, LiMn1.95Zn0.05O4 nanorods, and LiMn1.95Zn0.05O4 particles) present the intrinsic phase structure of LiMn2O4. SEM analysis shows that the LiMn1.95Zn0.05O4 nanorods preferably inherit the nano-rod morphology of γ-MnOOH nanorods. Electrochemical test results show that the combination of Zn-doping and nano-rod morphology has the synergetic effect for the significant improvement of cycling performance of LiMn2O4. When tested at 1.0 C, the LiMn1.95Zn0.05O4 nanorods exhibit satisfactory retention of 95.1% after 100 cycles with initial discharge capacity of 118.3 mAh g-1. Moreover, it demonstrates desirable rate performance, good high-temperature performance, and low charge transfer resistance. These results are mainly contributed by the combination of zinc-doping and nano-rod morphology, which effectively suppresses the Jahn-Teller effect, strengthen the spinel structure, and promote the transport rate of lithium ions and electronics.