Film strains enhance the reversible cycling of intercalation electrodes
Film strains enhance the reversible cycling of intercalation electrodes
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DOI：
10.1016/j.jmps.2021.104551
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发表时间：
2021-06
期刊：
影响因子：
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通讯作者：
De-long Zhang;J. Sheth;B. Sheldon;A. R. Balakrishna
中科院分区：
文献类型：
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作者：
De-long Zhang;J. Sheth;B. Sheldon;A. R. Balakrishna
电池电极化学机械退化的一个关键原因是它们在充放电周期中发生突然相变。这种相变伴随着晶格错配应变，形成微裂纹，诱发断裂，在极端情况下，使嵌入电极非晶化。在这项工作中，我们提出了一种防止插入电极化学-机械降解的策略：我们表明，通过工程设计合适的薄膜应变，我们可以调节薄膜插入电极的相变并避免大的体积变化。我们使用理论和实验相结合的方法来测试这一策略：我们首先分析得出薄膜应变对薄膜插入电极电化学响应的影响，然后将我们的分析模型应用于具有代表性的例子（lixv2o5多相转变）。然后我们用实验来检验我们的理论预测。具体来说，我们电化学循环了不同薄膜应变的v2o5薄膜电极，并测量了它们的结构、电压和应力响应。我们的研究结果表明，拉伸膜应变降低了薄膜v2o5电极相变的电压，并促进了它们在更宽的电压窗内的可逆循环，而不会发生化学-机械降解。这些结果表明，薄膜应变工程是防止插入电极化学-机械降解的另一种方法。除了薄膜电极之外，我们的研究结果也适用于颗粒基电极的应力诱导相变和阴极颗粒上形成的薄表面层的研究。
A key cause of chemo-mechanical degradation in battery electrodes is that they undergo abrupt phase transformation during the charging/discharging cycle. This phase transformation is accompanied by lattice misfit strains that nucleate microcracks, induce fracture and, in extreme cases, amorphize the intercalation electrode. In this work, we propose a strategy to prevent the chemo-mechanical degradation of intercalation electrodes: we show that by engineering suitable film strains we can regulate the phase transformations in thin-film intercalation electrodes and circumvent the large volume changes. We test this strategy using a combination of theory and experiment: we first analytically derive the effect of film strain on the electrochemical response of a thin-film intercalation electrode and next apply our analytical model to a representative example (LixV2O5with multiple phase transformations). We then test our theoretical predictions experimentally. Specifically, we electrochemically cycle thin-film V2O5electrodes with different film strains and measure their structure, voltage, and stress responses. Our findings show that tensile film strains lower the voltage for phase transformations in thin-film V2O5electrodes and facilitate their reversible cycling across a wider voltage window without chemo-mechanical degradation. These results suggest that film strain engineering is an alternative approach to preventing chemo-mechanical degradation in intercalation electrodes. Beyond thin-film electrodes, our findings from this study are applicable to the study of stress-induced phase transformations in particle-based electrodes and the thin surface layers forming on cathode particles.