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| 脱嵌锂循环过程中硅纳米材料变形原位测量与机理分析 |
| In-situ measurement of deformation of silicon nanomaterials and mechanism analysis during the lithiation and delithiation cycle |
| 投稿时间：2023-09-21 修订日期：2023-10-22 |
| DOI： |
| 中文关键词: 电化学诱导应变 硅纳米材料 非线性演化 原位测量 拉曼光谱 |
| 英文关键词:Electrochemical induced strain Silicon nanomaterials Nonlinear evolution In situ measurement Raman spectroscopy |
| 基金项目:国家自然科学基金项目（面上项目，重点项目，重大项目） |
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| 中文摘要: |
| 微结构变形测量与演化分析是研发高性能电极材料的重要基础，然而受限于电化学过程的复杂性和实验测量技术，目前纳米颗粒变形演化分析明显不足。本文针对高比容量硅纳米材料脱嵌锂循环过程中的应变演化分析开展微尺度原位实验研究。提出了电化学诱导应变的原位拉曼光谱测量方法，结合晶格动力学方程建立了电化学应变模型，实现了硅复合电极前两圈脱嵌锂循环过程中应变演化的原位测量。结果展示了多种实验新现象，如拉-压应变转变、倒“U”形非线性演化和应变滞后等。根据原位实验结果分析其应变演化过程并揭示机理，指出：第一圈嵌锂过程中持续增大的压应变起源于锂化相/晶硅相两相界面不断向中心扩散，除此之外脱嵌锂过程中压应变演化起源于梯度相的扩散。 |
| 英文摘要: |
| Microscale deformation measurement and evolution analysis are important foundations for the development of high-performance electrode materials. However, limited by the complexity of electrochemical processes and experimental measurement techniques, the deformation evolution analysis of nanoparticles is currently significantly insufficient. Therefore, this paper conducts microscale in-situ experimental investigation on the strain evolution of high specific capacity silicon nanomaterials during the lithiation and delithiation cycle. An in-situ Raman spectroscopy measurement method for electrochemical induced strain is proposed. An electrochemical strain model is established based on the lattice dynamics equation, realizing in-situ measurement of strain evolution during the first two lithiation and delithiation cycles in silicon composite electrode. The experimental results demonstrate some new phenomena, including strain tension-compression transition, strain nonlinear evolution with inverted "U" shape, and strain hysteresis. Furthermore, the process and mechanism of strain evolution are analyzed based on the in-situ experimental results. It is pointed out that the continuously increasing compressive strain during the first lithiation process originates from the continuous diffusion of the lithiated phase/crystalline silicon phase interface towards the center. In addition, the evolution of compressive strain during the other lithiation and delithiation process originates from the diffusion of gradient phases. |
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