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Abstract：
Metal sulfides have been intensively investigated for efficient sodium-ion storage due to their high capacity. However, the mechanisms behind the reaction pathways and phase transformation are still unclear. Moreover, the effects of designed nanostructure on the electrochemical behaviors are rarely reported. Herein, a hydrangea-like CuS microsphere is prepared via a facile synthetic method and displays significantly enhanced rate and cycle performance. Unlike the traditional intercalation and conversion reactions, an irreversible amorphization process is evidenced and elucidated with the help of in situ high-resolution synchrotron radiation diffraction analyses, and transmission electron microscopy. The oriented (006) crystal plane growth of the primary CuS nanosheets provide more channels and adsorption sites for Na ions intercalation and the resultant low overpotential is beneficial for the amorphous Cu-S cluster, which is consistent with the density functional theory calculation. This study can offer new insights into the correlation between the atomic-scale phase transformation and macro-scale nanostructure design and open a new principle for the electrode materials\' design.
摘要：
金属硫化物由于其高容量而被深入研究用于有效的钠离子储存。然而,反应途径和相变背后的机制尚不清楚。此外，设计的纳米结构对电化学行为的影响鲜有报道。在这里，通过简单的合成方法制备了绣球花状CuS微球，并显示出显着提高的速率和循环性能。与传统的嵌入和转化反应不同，在原位高分辨率同步辐射衍射分析的帮助下，证明和阐明了一个不可逆的非晶化过程，和透射电子显微镜。初级CuS纳米片的取向（006）晶面生长为Na离子插层提供了更多的通道和吸附位点，由此产生的低超电势有利于无定形Cu-S簇，这与密度泛函理论计算是一致的。这项研究可以为原子级相变与宏观纳米结构设计之间的相关性提供新的见解，并为电极材料的设计开辟了新的原理。
