Qin Xing, Zhou Mushang, Zong Bo, Guo Jianling, Gong Jiajia, Wang Li, Liang Guangchuan
Institute of Power Source and Ecomaterials Science, Hebei University of Technology Tianjin 300130 China
Key Laboratory of Special Functional Materials for Ecological Environment and Information (Hebei University of Technology), Ministry of Education Tianjin 300130 China.
RSC Adv. 2018 Aug 24;8(53):30087-30097. doi: 10.1039/c8ra05817b.
A hollow hierarchical LiNiMnO cathode material has been synthesized a urea-assisted hydrothermal method followed by a high-temperature calcination process. The effect of reactant concentration on the structure, morphology and electrochemical properties of the carbonate precursor and corresponding LiNiMnO product has been intensively investigated. The as-prepared samples were characterized by XRD, FT-IR, SEM, CV, EIS, GITT and constant-current charge/discharge tests. The results show that all samples belong to a cubic spinel structure with mainly 3 space group, and the Mn content and impurity content initially decrease and then increase slightly with the reactant concentration increasing. SEM observation shows that the particle morphology and size of carbonate precursor can be tailored by changing reactant concentration. The LiNiMnO sample obtained from the carbonate precursor hydrothermally synthesized at a reactant concentration of 0.3 mol L exhibits the optimal overall electrochemical properties, with capacity retention rate of 96.8% after 100 cycles at 1C rate and 10C discharge capacity of 124.9 mA h g, accounting for 99.9% of that at 0.2C rate. The excellent electrochemical performance can be mainly attributed to morphological characteristics, that is, smaller particle size with homogeneous distribution, in spite of lower Mn content.
采用尿素辅助水热法并结合高温煅烧工艺合成了一种空心分级结构的LiNiMnO正极材料。深入研究了反应物浓度对碳酸盐前驱体及相应LiNiMnO产物的结构、形貌和电化学性能的影响。通过XRD、FT-IR、SEM、CV、EIS、GITT和恒流充放电测试对所制备的样品进行了表征。结果表明，所有样品均属于立方尖晶石结构，主要为3种空间群，随着反应物浓度的增加，Mn含量和杂质含量最初降低，然后略有增加。SEM观察表明，通过改变反应物浓度可以调整碳酸盐前驱体的颗粒形貌和尺寸。由反应物浓度为0.3 mol L水热合成的碳酸盐前驱体制备的LiNiMnO样品表现出最佳的整体电化学性能，在1C倍率下循环100次后的容量保持率为96.8%，10C放电容量为124.9 mA h g，占0.2C倍率下放电容量的99.9%。优异的电化学性能主要归因于其形貌特征，即尽管Mn含量较低，但粒径较小且分布均匀。
