Wang Zhenzhu, Wang Jie, Ni Jiangfeng, Li Liang
School of Physical Science and Technology, Center for Energy Conversion Materials & Physics (CECMP), Jiangsu Key Laboratory of Thin Films, Soochow University, Suzhou, 215006, China.
Light Industry Institute of Electrochemical Power Sources, Suzhou, 215699, China.
Adv Sci (Weinh). 2022 May;9(16):e2201209. doi: 10.1002/advs.202201209. Epub 2022 Apr 1.
Metals such as Sb and Bi are important anode materials for sodium-ion batteries because they feature a large capacity and low reaction potential. However, the accumulation of stress and strain upon sodium storage leads to the formation of cracks and fractures, resulting in electrode failure upon extended cycling. In this work, the design and construction of Bi Sb bimetallic alloy films with a compositional gradient to mitigate the intrinsic structural instability is reported. In the gradient film, the top is rich in Sb, contributing to the capacity, while the bottom is rich in Bi, helping to reduce the stress in the interphase between the film and the substrate. Significantly, this gradient film affords a high reversible capacity of ≈500 mAh g and sustains 82% of the initial capacity after 1000 cycles at 2 C, drastically outperforming the solid-solution counterpart and many recently reported alloy anodes. Such a gradient design can open up the possibilities to engineering high-capacity anode materials that are structurally unstable due to the huge volume variation upon energy storage.
诸如锑和铋之类的金属是钠离子电池的重要负极材料，因为它们具有高容量和低反应电位的特点。然而，储存钠时应力和应变的积累会导致裂纹和裂缝的形成，从而在长时间循环后导致电极失效。在这项工作中，报告了具有成分梯度的铋锑双金属合金薄膜的设计与构建，以减轻其固有的结构不稳定性。在梯度薄膜中，顶部富含锑，有助于提高容量，而底部富含铋，有助于降低薄膜与基底之间界面处的应力。值得注意的是，这种梯度薄膜具有约500 mAh g的高可逆容量，在2 C下循环1000次后仍能保持初始容量的82%，大大优于固溶体对应物和许多最近报道的合金负极。这种梯度设计为设计由于储能时巨大的体积变化而结构不稳定的高容量负极材料开辟了可能性。
