Cao Kai, Wang Kangping, Shen Taotao, Wang Wenlou, Chen Dongming
Department of Chemical Physics, University of Science and Technology of China Hefei Anhui 230026 P. R. China
Nano Science and Technology Institute, University of Science and Technology of China Suzhou Jiangsu 215123 P. R. China.
RSC Adv. 2018 May 22;8(33):18589-18596. doi: 10.1039/c8ra03038c. eCollection 2018 May 17.
A lithium-rich layered oxide with different shell structures was synthesized by a simple wet-chemical surface deposition method. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and other techniques were applied to characterize the crystal structure, morphology, and micro-structure of the samples. The surface of the lithium-rich layered oxide can successively produce island-like spinel, ultra-thin spinel, and thick two-phase (spinel and amorphous manganese oxides) separation shell layers with an increase in the coating amount. The formation process of the different shell structures and the effect of the shell structure on the lattice parameters were discussed. The different shell structures play an important role in the electrochemical performance of the lithium-rich oxide. In particular, when the coating amount is 1 wt%, the lithium-rich material with a uniform LiMnO spinel shell layer exhibits superior electrochemical performance, and can maintain a discharge capacity of 209.9 mA h g and 166.8 mA h g at rates of 2C and 5C.
通过一种简单的湿化学表面沉积方法合成了具有不同壳层结构的富锂层状氧化物。采用X射线衍射（XRD）、扫描电子显微镜（SEM）、透射电子显微镜（TEM）、X射线光电子能谱（XPS）等技术对样品的晶体结构、形貌和微观结构进行了表征。随着包覆量的增加，富锂层状氧化物的表面可依次产生岛状尖晶石、超薄尖晶石和厚的两相（尖晶石和非晶态锰氧化物）分离壳层。讨论了不同壳层结构的形成过程以及壳层结构对晶格参数的影响。不同的壳层结构对富锂氧化物的电化学性能起着重要作用。特别是当包覆量为1 wt%时，具有均匀LiMnO尖晶石壳层的富锂材料表现出优异的电化学性能，在2C和5C倍率下可分别保持209.9 mA h/g和166.8 mA h/g的放电容量。
