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 (Li_xV₂O₅ with multiple phase transformations). We then test our theoretical predictions experimentally. Specifically, we electrochemically cycle thin-film V₂O₅ electrodes 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 V₂O₅ electrodes 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.

电池电极化学机械退化的一个关键原因是它们在充电/放电循环期间经历了突然的相变。这种相变伴随着晶格失配应变，使微裂纹成核，诱导断裂，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层电极化学机械退化的策略：我们表明，通过设计合适的薄膜应变，我们可以调节薄膜插层电极中的相变并避免大的体积变化。我们结合理论和实验来测试这个策略：_x V ₂ O ₅具有多个相变）。然后我们通过实验测试我们的理论预测。具体而言，我们对具有不同薄膜应变的薄膜 V ₂ O ₅电极进行电化学循环，并测量它们的结构、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 V ₂ O _{5 中}相变的电压电极并促进它们在更宽的电压窗口内可逆循环，而不会发生化学机械退化。这些结果表明，薄膜应变工程是防止嵌入电极中化学机械降解的另一种方法。除了薄膜电极之外，我们从这项研究中得到的发现适用于研究粒子基电极中的应力诱导相变和阴极粒子上形成的薄表面层。