Interfacial degradation of silicon anodes in pouch cells,Energy & Environmental Science

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Interfacial degradation of silicon anodes in pouch cells
Energy & Environmental Science ( IF 32.4 ) Pub Date : 2024-08-06 , DOI: 10.1039/d4ee01755b
Qiu Fang _{1,

2} , Shiwei Xu _{1,

3} , Xuechao Sha ₄ , Di Liu ₄ , Xiao Zhang _{1,

2} , Weiping Li _{1,

2} , Suting Weng _{1,

3} , Xiaoyun Li _{1,

2} , Liquan Chen ₁ , Hong Li _{1,

2,

3,

5} , Bo Wang _{6,

7} , Zhaoxiang Wang _{1,

2,

3} , Xuefeng Wang _{1,

2,

3}

Affiliation

The practical application of silicon (Si) anodes in the next-generation high-energy lithium-ion batteries (LIBs) is largely hindered by their capacity loss due to the formation of a solid electrolyte interphase (SEI). Although much work has been carried out to investigate the interfacial evolution of Si, most of them focused on nanostructured Si cycled in coin cells or customer-designed cells, whose working conditions are far from practical usage. Herein, the capacity degradation mechanism and associated interfacial evolution of the micro-sized Si particles cycled in pouch cells are uncovered through multi-scale imaging and spectroscopy techniques, especially cryogenic electron microscopy (cryo-EM). The results show that the surface of Si particles is gradually corroded by the electrolyte, forming a thick (up to 2.5 μm after 300 cycles) and porous SEI rich in organic carbonates and Li_xSiO_y. After profiling the nanostructure and chemical distribution across it, the porosity of the SEI is determined to be ∼53.5% and thus a bottom-up SEI growth mechanism is proposed. To achieve a dense and stable SEI, an elastic SEI with a crosslinking network is used to enhance the interfacial stability of the Si anode. Our findings not only reveal the underlying failure mechanism of the Si anode beneficial for its practical applications but also provide a comprehensive understanding of dynamic interfacial evolution enlightening for future interfacial design to achieve high-performance batteries.

中文翻译：

软包电池中硅阳极的界面降解

硅（Si）阳极在下一代高能锂离子电池（LIB）中的实际应用在很大程度上受到固体电解质界面（SEI）形成导致的容量损失的阻碍。尽管已经开展了大量工作来研究硅的界面演化，但其中大多数都集中在纽扣电池或客户设计的电池中循环的纳米结构硅，其工作条件与实际使用相距甚远。在此，通过多尺度成像和光谱技术，特别是低温电子显微镜（cryo-EM）揭示了软包电池中循环的微米尺寸硅颗粒的容量退化机制和相关的界面演变。结果表明，Si颗粒表面逐渐被电解液腐蚀，形成一层厚的（300次循环后可达2.5μm）多孔SEI，富含有机碳酸盐和Li _x SiO _y 。在分析了纳米结构和化学分布后，SEI 的孔隙率确定为 ~53.5%，因此提出了自下而上的 SEI 生长机制。为了实现致密且稳定的SEI，使用具有交联网络的弹性SEI来增强硅阳极的界面稳定性。我们的研究结果不仅揭示了硅负极的潜在失效机制，有利于其实际应用，而且还提供了对动态界面演化的全面理解，为未来实现高性能电池的界面设计提供了启发。

更新日期：2024-08-06

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