棒状尖晶石型LiMn_2O_4材料的合成及其性能研究

Performance of Rodlike Spinel Li Mn_2O_4 Material Preprared with Urchin-like β-MnO_2Precursor

以MnSO_4·H_2O与NaClO_3为原料,NH_4F为辅助剂,通过水热法合成了海胆状β-MnO_2前驱体,研究了NH_4F用量对前驱体形貌的影响。以形貌最优的β-MnO_2作为前驱体与LiOH·H_2O通过高温烧结合成棒状尖晶石型LiMn_2O_4,并将它与商业MnO_2为前驱体合成的尖晶石型LiMn_2O_4进行了结构和性能比较。通过X射线衍射分析(XRD)、扫描电镜(SEM)以及电化学性能测试等手段对MnO_2前驱体以及尖晶石型LiMn_2O_4产物进行了表征。实验结果表明,棒状LiMn_2O_4具有更优越的电化学性能:0.2C下首次放电比容量为119.8 m Ah/g,最高达到123.2 m Ah/g,30圈循环后,容量保持率为94.07%。

Urchin-like β-MnO_2 was prepared by a hydrothermal method via a redox reaction between NaClO_3 and MnSO_4·H_2O assisted with NH_4F,and the effect of NH_4F dosage on the morphology of β-MnO_2 was studied. Usingβ-MnO_2 with the best morphology as the precursor,rodlike spinel LiMn2O4 was synthesized by sintering of the precursor with LiOH·H_2 O,and its structure and performance were evaluated by comparing with spinel Li Mn2O4 prepared with commercial MnO_2 as the precursor. X-ray diffraction（ XRD）,scanning electron microscopy（ SEM） and electrochemical performance test were used to characterize MnO_2 precursors and LiMn_2O_4 products. The results show that,rodlike LiMn_2O_4 exhibits superior electrochemical properties,with the initial and the highest discharge capacity in 0. 2C reaching119.8 m Ah / g and 123.2 m Ah / g,respectively,and capacity retention ratio remaining to be 94.07% after 30 cycles.