Antisite defects are a type of point defect ubiquitously present in intercalation compounds for energy storage applications. While they are often considered a deleterious feature, here we elucidate a mechanism of antisite defects enhancing lithium intercalation kinetics in LiFePO₄ by accelerating the FePO₄ → LiFePO₄ phase transformation. Although Fe_Li antisites block Li movement along the [010] migration channels in LiFePO₄, phase-field modeling reveals that their ability to enhance Li diffusion in other directions significantly increases the active surface area for Li intercalation in the surface-reaction-limited kinetic regime, which results in order-of-magnitude improvement in the phase transformation rate compared to defect-free particles. Antisite defects also promote a more uniform reaction flux on (010) surface and prevent the formation of current hotspots under galvanostatic (dis)charging conditions. We analyze the scaling relation between the phase boundary speed, Li diffusivity and particle dimensions and derive the criteria for the co-optimization of defect content and particle geometry. A surprising prediction is that (100)-oriented LiFePO₄ plates could potentially deliver better performance than (010)-oriented plates when the Li intercalation process is surface-reaction-limited. Our work suggests tailoring antisite defects as a general strategy to improve the rate performance of phase-changing battery compounds with strong diffusion anisotropy.

反位缺陷是插层化合物中普遍存在的一种点缺陷，用于能量存储应用。尽管通常将它们视为有害特征，但在此我们阐明了通过加速FePO ₄  →LiFePO ₄相变来增强LiFePO _4中锂嵌入动力学的反位缺陷机理。尽管铁_锂的反位点会阻止锂在LiFePO _4中沿[010]迁移通道移动。，相场建模表明，它们增强Li在其他方向上的扩散的能力显着增加了在表面反应受限的动力学范围内嵌入Li的有效表面积，与相变速率相比，其幅值得到了改善无缺陷的颗粒。反位缺陷还可以促进（010）表面上更均匀的反应通量，并防止在恒流（放电）放电条件下形成当前的热点。我们分析了相边界速度，Li扩散率和颗粒尺寸之间的比例关系，并得出了缺陷含量和颗粒几何形状共同优化的标准。令人惊讶的预测是（100）取向的LiFePO ₄当Li嵌入过程受到表面反应限制时，这些板可能比（010）取向的板具有更好的性能。我们的工作建议定制反位缺陷作为提高具有强扩散各向异性的相变电池化合物的速率性能的一般策略。