Yang Juan, Zhang Jiaming, Zhou Xiangyang, Ren Yongpeng, Jiang Min, Tang Jingjing
School of Metallurgy and Environment , Central South University , Changsha 410083 , China.
ACS Appl Mater Interfaces. 2018 Oct 17;10(41):35216-35223. doi: 10.1021/acsami.8b12242. Epub 2018 Oct 2.
To address the huge volumetric change and unstable solid electrolyte interphase (SEI) issues of Sn-based anodes, this paper proposes a Sn-Co-C ternary composite with a cubic yolk-shell structure. The proposed Sn-Co nanoalloys encapsulated in N-doped carbon hollow cubes (Sn-Co@C) are simply synthesized by the conformal polydopamine coating of home-made CoSn(OH) hollow nanocubes subsequent with hydrogen reduction. The cubic Sn-Co@C yolk-shell structure possessing an optimized carbon shell thickness displays excellent cyclic performance and superior rate capability when utilized as an anode for lithium-ion batteries. The composite shows an initial discharge capacity of 885 mA h g at 200 mA g with a high capacity retention of ∼91.2% after 180 cycles. It can still deliver a considerable capacity of 560 mA h g at a high current density of 1 A g after 200 cycles. This attractive electrochemical characteristic can be ascribed to the distinct cubic yolk-shell architecture, in which the inner inactive Co can buffer the volumetric expansion of Sn, the void can provide external space for the volumetric change of Sn, and the outer carbon shell can effectively prevent the agglomeration of Sn-Co nanoalloys and maintain the stability of SEI films.
为了解决锡基负极巨大的体积变化和不稳定的固体电解质界面（SEI）问题，本文提出了一种具有立方蛋黄壳结构的Sn-Co-C三元复合材料。封装在氮掺杂碳空心立方体中的拟议Sn-Co纳米合金（Sn-Co@C）通过对自制的CoSn(OH)空心纳米立方体进行聚多巴胺保形包覆随后进行氢还原简单合成。当用作锂离子电池的负极时，具有优化碳壳厚度的立方Sn-Co@C蛋黄壳结构表现出优异的循环性能和卓越的倍率性能。该复合材料在200 mA g下的初始放电容量为885 mA h g，180次循环后具有约91.2%的高容量保持率。在200次循环后，在1 A g的高电流密度下仍可提供560 mA h g的可观容量。这种有吸引力的电化学特性可归因于独特的立方蛋黄壳结构，其中内部的惰性Co可以缓冲Sn的体积膨胀，空隙可为Sn的体积变化提供外部空间，而外部碳壳可以有效防止Sn-Co纳米合金的团聚并保持SEI膜的稳定性。
