Abstract

We report on a rationally designed microsphere composite consisting of Nb₂O₅ and Si nanoparticles for application to secondary Li batteries as an anode material. The micron-sized spherical Nb₂O₅–Si composite was first prepared using a solvothermal method with appropriate surfactants. Heat treatment was performed to achieve both crystallization of Nb₂O₅ and pyrolysis of the carbon precursor, yielding a carbon-coated Nb₂O₅–Si microsphere composite. To characterize the synthesized material, X-ray diffraction, electron microscopy, and X-ray photoelectron spectroscopy were employed. The electrochemical test results demonstrated that the composite electrode delivered a high capacity of approximately 900 mAh g⁻¹ after 100 cycles. This improved cycling stability can be attributed to the microstructure. In the microsphere composite, Si nanoparticles play a role as the main active material for Li storage; however, they suffer large volume changes during Li insertion and extraction cycling. In our composite material, crystallized orthorhombic Nb₂O₅ buffers the volume change and facilitates rapid Li transport through its microspheres. Additionally, the carbon coating layer acts as a secondary buffering medium and propels fast electronic/ionic transport.

Graphic Abstract

中文翻译：

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碳包Nb 2 O 5 -Si复合材料为可逆锂存储材料的组织设计

摘要

我们报告了由Nb ₂ O ₅和Si纳米粒子组成的合理设计的微球复合材料，可用于二次Li电池作为负极材料。首先使用溶剂热法和适当的表面活性剂制备微米级球形Nb ₂ O ₅ -Si复合材料。进行热处理以实现Nb ₂ O _5的结晶和碳前体的热解，从而得到碳涂层的Nb ₂ O ₅–Si微球复合材料。为了表征合成的材料，使用了X射线衍射，电子显微镜和X射线光电子能谱。电化学测试结果表明，复合电极在100次循环后提供了约900 mAh g ^-1的高容量。这种改善的循环稳定性可以归因于微观结构。在微球复合材料中，Si纳米颗粒起着锂存储的主要活性材料的作用。然而，在锂的插入和提取循环中，它们的体积变化很大。在我们的复合材料中，结晶的正交晶Nb ₂ O ₅缓冲体积变化，并促进锂通过其微球的快速运输。另外，碳涂层充当辅助缓冲介质并推动快速的电子/离子传输。

图形摘要