LaMO_(3)(M=Mn、Fe、Co、Ni)的制备及储锂性能研究

Preparation and lithium storage properties of LaMO_(3)(M=Mn,Fe,Co,Ni)

镧基钙钛矿型氧化物因其理论容量高、制备简单、原材料丰富等优点深得科研人员的青睐,但是这类材料仍然存在不足,即容量易衰减,电导率低,在脱嵌锂过程中大的体积效应。本文采用简单的溶胶凝胶法制备不同B组分的钙钛矿氧化物,分别制备了LaMO_(3)(M=Mn、Fe、Co、Ni)钙钛矿氧化物材料。采用X射线衍射仪测试样品的晶体结构,使用Rietveld方法对XRD数据进行精修处理,采用场发射扫描电子显微镜观察样品的形貌和微观结构,最后将电极材料组装成CR2032扣式电池来评价电极材料的电化学性能,采用多种电化学测试手段分析各自的电化学性能。研究发现,由溶胶-凝胶法制备的镧基钙钛矿氧化物的粒径大小不同,电化学性能有所差异。其中,LaNiO_(3)纳米颗粒在500 mA·g^(-1)电流密度下循环500周后放电比容量达到了573.8 mAh·g^(-1),并且曲线更平稳且呈持续增长趋势。即使在5 A·g^(-1)的大电流密度下,放电容量仍然能达到146 mAh·g^(-1),明显高于其他三种材料。最后,本文总结了LaNiO_(3)电化学性能优异的原因。

Lanthanide-based perovskite-type oxides are deeply favored by researchers because of their high theoretical capacity,simple preparation,and abundance of raw materials,but these materials still have shortcomings,i.e.,the capacity is prone to decay,the conductivity is low,and the volumetric effect during de-embedded lithium process.In this paper,LaMO_(3)(M=Mn,Fe,Co,Ni)chalcogenide oxide materials with different B-components were prepared by a simple sol-gel method.X-ray diffractometer was used to test the crystal structure of the samples,Rietveld method was used to fine-tune the XRD data,field emission scanning electron microscope was used to observe the morphology and microstructure of the samples,and finally,the electrode materials were assembled into a CR2032 battery to evaluate the electrochemical properties of the electrode materials,and multiple electrochemical tests were used to analyze the respective electrochemical properties.It was found that the electrochemical properties of LaMO3(M=Co,Fe,Mn,Ni)prepared by sol-gel method varied with different particle sizes.Among them,LaNiO_(3) nanoparticles own the discharge specific capacity reaches 573.8 mAh·g^(-1) after 500 cycles at 500 mA·g-1 with a smoother curve and a continuous growth trend.Even though at a high current density of 5 A·g^(-1),its discharge capacity also reaches 146 mAh·g^(-1),which is significantly higher than that of the other three materials.Finally,the paper summarizes the reasons for the excellent electrochemical performance of LaNiO_(3).