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 LiMn₂O₄ positive materials. A facile strategy of manipulating the KMnO₄ concentration is introduced to precisely fabricate 1 D LiMn₂O₄ 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 Mn²⁺ is electrochemically inactive on the surface of the sample, which explains the adverse effects observed on LiMn₂O₄ nanorods with the minimum diameter of 30–40 nm, such as decreased discharge capacity. The LiMn₂O₄ 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.

中文翻译：

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锂离子电池一维尖晶石LiMn2O4正极材料的可控制备和锂存储动力学：临界直径的探索

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，由于其优异的Li ⁺扩散动力学，已经对锂离子电池的一维电极材料进行了深入研究。人们普遍认为，较小尺寸的电极材料可导致更好的锂存储动力学。在这项研究中，发现在1 D LiMn ₂ O ₄正极材料中情况并非如此。引入了一种控制KMnO ₄浓度的简便策略来精确制造1 D LiMn ₂ O ₄纳米棒具有从30到170 nm的四个不同的直径梯度。通过比较表征方法阐明了一维晶体尺寸在影响界面化学物种和电化学性能中的作用。X射线光电子能谱（XPS）的Ar离子蚀刻技术表明Mn ²⁺在样品表面上是电化学惰性的，这解释了在最小直径30–40 nm的LiMn ₂ O ₄纳米棒上观察到的不利影响，例如放电容量降低。LiMn ₂ O ₄临界直径约为70–80 nm的纳米棒显示出最高的放电容量和有希望的循环性能。这项工作阐明了以前被忽略的重要特性，并加深了对锰基正极材料设计的理解。