Elsevier

Ceramics International

Volume 42, Issue 5, April 2016, Pages 5693-5698
Ceramics International

Electrochemical evaluation of LiZnxMn2−xO4 (x≤0.10) cathode material synthesized by solution combustion method

https://doi.org/10.1016/j.ceramint.2015.12.098Get rights and content

Abstract

The spinel LiZnxMn2−xO4 (x≤0.10) cathode materials have been synthesized by solution combustion method at 600 °C for 3 h. The structure and the morphology of LiZnxMn2−xO4 were characterized by X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM), respectively. All the obtained samples were identified as the spinel structure of LiMn2O4, the lattice parameters of samples decreased and the particle size increased as the Zn content increased. The effects of Zn-doping on the electrochemical characteristics of LiMn2O4 were investigated by galvanostatic charge–discharge experiments, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Among them, LiZn0.05Mn1.95O4 particles presented outstanding cycling stability with a capacity retention of 82.9% at a discharge rate of 1 C (1 C=148 mA h g−1) after 500 cycles. Spinel LiZn0.05Mn1.95O4 had reversible cycling performance, revealing that doping LiMn2O4 with Zn improves its electrochemical performance.

Introduction

Recently, many researchers are interested in spinel LiMn2O4 for its low cost, superior safety and environmental friendliness etc. [1], [2], [3]. Nevertheless, the capacity fading of LiMn2O4 is a deadly obstacle which limits its commercial use. The reasons of the spinel LiMn2O4 capacity fade were mainly included the following several factors: (1) the dissolution of Mn3+, (2) the Jahn–Teller distortion effect, (3) the decomposition of electrolyte [4], [5], [6]. To restrict the Jahn–Teller distortion effect, the partial substitutions of Mn by other cations, such as Ni2+ [7], [8], Si4+ [9], [10], Mg2+ [11], [12], Cu2+ [13], [14], Al3+ [15], [16] and Zn2+ [17], [18] have been studied and single doped or multiple doped has been proposed as an effective way to inhibit capacity fading upon cycling. Among these materials, the single Zn2+ ion doped LiMn2O4 were studied only by a few researchers [18], [19], [20]. Zn2+ doped spinel LiMn2O4 with improved cycling stability was reported that Gummow et al. [18]. Ein-Eli et al. [19] synthesized the LiZnxMn2−xO4 (x=0, 0.25 and 0.5) by sol–gel method and Zn doped spinel LiZn0.25Mn1.75O4 delivered discharge capacity of 70 mA h g−1 during the first cycle. Arumugam et al. [20] prepared spinel LiZnxMn2−xO4 (x=0.00–0.15) by sol–gel technique using succinic acid as the chelating agent, and among them Zn doped spinel LiZn0.10Mn1.90O4 has improved the structural stability, high reversible capacity and excellent electrochemical performance of rechargeable lithium batteries. The initial discharge capacities for LiZn0.10Mn1.90O4 is 117 mA h g−1 at 1 C, and the capacity retention reached 58% after 100 cycles. To the best of our knowledge, no reports are available in the literature about the Zn-doped LiMn2O4 prepared via solution combustion route.

In this work, LiZnxMn2−xO4 (x≤0.10) cathode materials were produced by solution combustion method, and the structural, morphology and performance of the spinel LiZnxMn2−xO4 materials were studied in detail.

Section snippets

Experimental

The spinel LiZnxMn2−xO4 (x=0, 0.02, 0.05, and 0.10) samples were prepared by H3NO3-assisted solution combustion method, and stoichiometric raw materials of LiNO3, Mn(CH3COO)2·4H2O and Zn(CH3COO)2·2H2O were weighted and placed into a 300 mL crucible. Then, the 9 mol L−1 nitric acid were added to the mixture. Finally, the mixture was heated in a muffle furnace at 600 °C for 3 h. LiZnxMn2−xO4 powders were obtained after cooling to room temperature. The electrode for electrochemical test was prepared by

Structure analysis

The XRD patterns of the LiZnxMn2−xO4 (x=0, 0.02, 0.05, and 0.10) samples presented in Fig. 1 exhibit the characteristic diffraction peaks of cubic spinel LiMn2O4 with the Fd3m space group (JCPDS, PDF 35-0782) corresponding to the eight crystal planes of (111), (311), (222), (400), (331), (511), (440) and (531). There is no significant difference in the crystal structure after Zn substitution. This indicates the addition of Zn does not change the spinel structure of LiMn2O4. However, a small

Conclusions

Zn-doped LiZnxMn2−xO4 powders were successfully synthesized via solution combustion method. The agglomeration of the samples decreased with increasing Zn content. LiZn0.05Mn1.95O4 produced by this method exhibited a capacity retention of 82.9% at a discharge rate of 1 C after 500 cycles, showing excellent cycling stability. LiZn0.05Mn1.95O4 showed good reversibility and a high peak current in electrochemical studies, which are favorable for electrodes in LIBs. Electrochemical impedance

Acknowledgments

This work was financially supported by the National Natural Science Foundation of China (51262031, 51462036), Program for Innovative Research Team (in Science and Technology) in University of Yunnan Province (2011UY09), Yunnan Provincial Innovation Team (2011HC008), and Innovation Program of Yunnan Minzu University (2015TX09, 2015YJCXZ24, 2015YJCXZ21).

References (29)

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