Electrolyte Role in SEI Evolution at Si in the Pre-lithiation Stage vs the Post-lithiation Stage
Electrolyte Role in SEI Evolution at Si in the Pre-lithiation Stage vs the Post-lithiation Stage
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锂化前阶段与锂化后阶段电解质在 Si 的 SEI 演变中的作用
DOI：
10.1149/1945-7111/acb617
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发表时间：
2023
影响因子：
3.9
通讯作者：
Sa, Niya
中科院分区：
文献类型：
--
作者：
Cora, Saida;Key, Baris;Vaughey, John;Sa, Niya
为了解决不可逆容量损失和延长电池循环寿命，尚未完全了解硅阳极/电解质界面处动态固体电解质界面（SEI）的形成和演变。在此，研究了两种电解质体系中SEI的演变及其在Si阳极/电解质界面的动态特性，即EC：EMC 3：7（wt％）电解质中的1.2 M LiPF 6（称为Gen2）和EC：EMC 3：7（wt％）电解质中的1.2 M LiTFSI（称为LiTFSI）。研究了两个锂化阶段：锂化前（pre-Li）SEI阶段和锂化后（post-Li）阶段。研究结果表明，在前锂阶段，SEI 的形成开始于早期，并有助于 Si/Gen2 中更大的质量增益，其主要是在 Si/Gen2 中形成不均匀的富 F 和 P 层，与 Si/LiTFSI 界面处的均匀含 F 和 C 层形成鲜明对比。 LiTFSI 中最初形成的 SEI 进一步有利于电荷转移动力学。在后 Li 阶段，在 Si/LiTFSI 中观察到更显着的 SEI 演变。这项研究提供了对电解质依赖性 SEI 动态演化的基础理解。本报告的研究结果为解决 Si 上复杂的 SEI 稳定性问题提供了重要见解。
The formation and evolution of the dynamic solid electrolyte interphase (SEI) at the Si anode/electrolyte interface are yet to be completely understood to solve irreversible capacity loss and increase battery cycle life. Herein, the evolution of SEI and its dynamic properties at the Si anode/electrolyte interface are investigated in two electrolyte systems, a 1.2 M LiPF 6 in EC: EMC 3: 7 (wt%) electrolyte (referred to as Gen2) and a 1.2 M LiTFSI in EC: EMC 3: 7 (wt%) electrolyte (referred to as LiTFSI). Two lithiation stages are studied: the pre-lithiation (pre-Li) SEI stage and the post-lithiation (post-Li) stage. Findings reveal at the pre-Li, SEI formation starts at an early potential and contributes to the greater mass gain in the Si/Gen2, and it is dominated by the formation of a non-uniform F-and P-rich layer in Si/Gen2, in contrast to a homogeneous F-and C-containing layer at the Si/LiTFSI interphase. The initially formed SEI in LiTFSI further benefits the charge transfer kinetics. At the post-Li stage, a more substantial SEI evolution is observed at Si/LiTFSI. This study offers a foundational understanding of the SEI dynamic evolution with electrolyte dependence. Findings from this report offer important insights into solving the complex SEI stability issues on Si.