Zhu Chengyi, Zhang Yannan, Yu Xiaohua, Dong Peng, Duan Jianguo, Liu Jiaming, Liu Jianxiong, Zhang Yingjie
National and Local Joint Engineering Laboratory for Lithium-ion Batteries and Materials Preparation Technology, Key Laboratory of Advanced Battery Materials of Yunnan Province, Faculty of Materials Science and Engineering, Kunming University of Science and Technology, Kunming, 650093, P.R. China.
National and Local Joint Engineering Laboratory for Lithium-Ion Batteries and Materials Preparation Technology, Key Laboratory of Advanced Battery Materials of Yunnan Province, Faculty of Metallurgical and Energy Engineering, Kunming University of Science and Technology, Kunming, 650093, P.R. China.
ChemSusChem. 2020 Feb 21;13(4):803-810. doi: 10.1002/cssc.201902846. Epub 2020 Jan 21.
The morphology and size of nanoelectrode materials determine their properties. Compared to the bulk structure electrodes, 1 D electrode materials for Li-ion batteries have been intensively studied owing to their excellent Li diffusion kinetics. It is generally accepted that smaller-sized electrode materials lead to better Li storage kinetics. In this study, this is found to not be the case in 1 D LiMn O positive materials. A facile strategy of manipulating the KMnO concentration is introduced to precisely fabricate 1 D LiMn O nanorods with four distinct diameter gradients from 30 to 170 nm. The role of 1 D crystal size in effecting interface chemical species and electrochemical performance is elucidated by comparative characterization methods. X-ray photoelectron spectroscopy (XPS) Ar-ion etching technology shows that the Mn is electrochemically inactive on the surface of the sample, which explains the adverse effects observed on LiMn O nanorods with the minimum diameter of 30-40 nm, such as decreased discharge capacity. The LiMn O nanorod with a critical diameter of approximately 70-80 nm displays the highest discharge capacity and promising cycling performance. This work clarifies an important property that has previously been neglected and deepens the understanding for design of Mn-based positive materials.
纳米电极材料的形态和尺寸决定了它们的性能。与块状结构电极相比，锂离子电池的一维电极材料因其优异的锂扩散动力学而受到广泛研究。人们普遍认为，尺寸较小的电极材料具有更好的锂存储动力学。在本研究中，发现一维LiMnO正极材料并非如此。引入了一种控制KMnO浓度的简便策略，以精确制备具有30至170 nm四个不同直径梯度的一维LiMnO纳米棒。通过比较表征方法阐明了一维晶体尺寸对界面化学物种和电化学性能的影响。X射线光电子能谱（XPS）氩离子蚀刻技术表明，样品表面的Mn在电化学上是不活跃的，这解释了在最小直径为30-40 nm的LiMnO纳米棒上观察到的不利影响，如放电容量降低。临界直径约为70-80 nm的LiMnO纳米棒表现出最高的放电容量和良好的循环性能。这项工作阐明了一个以前被忽视的重要性质，并加深了对锰基正极材料设计的理解。
