锂离子电池条件下界面化学对硅电极电化学性能的影响,Small

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锂离子电池条件下界面化学对硅电极电化学性能的影响
Small ( IF 13.0 ) Pub Date : 2023-06-03 , DOI: 10.1002/smll.202303442
Xiangdong Xu ₁ , Daniel Martín-Yerga _{1,

2} , Nicholas E Grant ₃ , Geoff West ₄ , Sophie L Pain ₃ , Minkyung Kang ₅ , Marc Walker ₆ , John D Murphy ₃ , Patrick R Unwin _{1,

2}

Affiliation

了解硅 (Si) 电极上固体电解质界面 (SEI) 的形成和（脱）锂现象是提高硅基锂离子电池性能和寿命的关键。然而，这些工艺仍然有些难以捉摸，特别是硅表面终端的作用值得进一步考虑。在这里，在手套箱中使用扫描电化学电池显微镜 (SECCM)，然后在相同位置进行二次离子质谱 (SIMS)，以研究局部电化学行为和相关的 SEI 形成，将 Si (100) 与天然氧化物层 (SiO2) 进行比较_x /Si）并用氢氟酸（HF-Si）蚀刻。_{与SiO x} /Si相比，HF-Si表现出更大的空间电化学异质性和较差的锂化可逆性。这归因于弱钝化SEI和Si表面不可逆的锂捕获。通过 SECCM 与同位 SIMS 对充电/放电循环进行组合筛选，揭示了 SEI 化学与深度的函数关系。虽然 SEI 厚度相对独立于循环次数，但化学成分（尤其是中间层）取决于循环次数，这表明 SEI 在循环过程中是动态的。这项工作为使用相关 SECCM/SIMS 作为一种强大的方法奠定了基础，以获取纳米和微米尺度上复杂电池过程的基本见解。

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Interfacial Chemistry Effects in the Electrochemical Performance of Silicon Electrodes under Lithium-Ion Battery Conditions

Understanding the solid electrolyte interphase (SEI) formation and (de)lithiation phenomena at silicon (Si) electrodes is key to improving the performance and lifetime of Si-based lithium-ion batteries. However, these processes remain somewhat elusive, and, in particular, the role of Si surface termination merits further consideration. Here, scanning electrochemical cell microscopy (SECCM) is used in a glovebox, followed by secondary ion mass spectrometry (SIMS) at identical locations to study the local electrochemical behavior and associated SEI formation, comparing Si (100) with a native oxide layer (SiO_x/Si) and etched with hydrofluoric acid (HF-Si). HF-Si shows greater spatial electrochemical heterogeneity and inferior lithiation reversibility than SiO_x/Si. This is attributed to a weakly passivating SEI and irreversible lithium trapping at the Si surface. Combinatorial screening of charge/discharge cycling by SECCM with co-located SIMS reveals SEI chemistry as a function of depth. While the SEI thickness is relatively independent of the cycle number, the chemistry – particularly in the intermediate layers – depends on the number of cycles, revealing the SEI to be dynamic during cycling. This work serves as a foundation for the use of correlative SECCM/SIMS as a powerful approach to gain fundamental insights on complex battery processes at the nano- and microscales.

更新日期：2023-06-03

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