Zhu Chaoye, Zhang Yao, Ma Zhihong, Wang Hui, Sly Gunnar L
School of Materials Science and Engineering, Jiangsu Key Laboratory of Advanced Metallic Materials, Southeast University, Nanjing 211189, People's Republic of China.
School of Materials Science & Engineering, Baise University, Baise 533000, Guangxi, People's Republic of China.
Nanotechnology. 2021 Feb 19;32(8):085403. doi: 10.1088/1361-6528/abc77f.
Silicon is a promising anode for new-generation lithium ion batteries due to high theoretical lithium storage capacity (4200 mAh g). However, the low conductivity and large volumetric expansion hamper the commercialization of the silicon anode. In this case, we present a yolk-void-shell Si-C anode (denoted as Si@Void@C), which is synthesized through nano-Si oxidation, surface carbonization and etching of SiO . The void can be fabricated only by the self-generation and etching of SiO layer on the Si surface, without the help of template materials. Moreover, the void size can be adjusted only by means of the annealing temperature, which can be easily and precisely operated. The Si@Void@C/rGO with void size of 5 nm offers a discharge capacity of 1294 mAh g after 100 cycles at a current density of 500 mA g. These enhanced performances can be ascribed to an appropriate size (5 nm) of void space which sufficiently accommodates the silicon volume expansion and stabilizes the carbon shell. At the same time, the voids effectively inhibit the growth of the solid electrolyte interface layer by depressing the decomposition of the electrolyte on the surface of Si in Si@Void@C/rGO. Furthermore, interfaces between Si@Void@C particles and rGO sheets construct bridges for electrons' conduction. In general, the present work provides a viable strategy for synthesizing silicon-carbon anode materials with long life.
由于具有较高的理论锂存储容量（4200 mAh/g），硅是新一代锂离子电池中很有前景的负极材料。然而，低导电性和大体积膨胀阻碍了硅负极的商业化。在这种情况下，我们提出了一种蛋黄-空隙-壳结构的硅-碳负极（表示为Si@Void@C），它是通过纳米硅氧化、表面碳化和SiO₂蚀刻合成的。空隙仅通过硅表面SiO₂层的自生和蚀刻即可形成，无需模板材料的帮助。此外，空隙尺寸仅可通过退火温度进行调节，操作简便且精确。空隙尺寸为5 nm的Si@Void@C/rGO在500 mA/g的电流密度下循环100次后，放电容量为1294 mAh/g。这些增强的性能可归因于适当尺寸（5 nm）的空隙空间，其足以容纳硅的体积膨胀并稳定碳壳。同时，空隙通过抑制Si@Void@C/rGO中硅表面电解质的分解，有效地抑制了固体电解质界面层的生长。此外，Si@Void@C颗粒与rGO片之间的界面为电子传导搭建了桥梁。总的来说，本工作为合成具有长寿命的硅-碳负极材料提供了一种可行的策略。
