Lithium iron phosphate (LiFePO₄) is the prototypical two-phase battery material whose complex patterns of lithium ion intercalation provide a testing ground for theories of electrochemical thermodynamics. Using a depth-averaged (a-b plane) phase-field model of coherent phase separation driven by Faradaic reactions, we reconcile conflicting experimental observations of diamond-like phase patterns in micron-sized platelets with observations of surface-controlled patterns in nanoparticles. Elastic analysis predicts this morphological transition for particles whose a-axis dimension exceeds twice the bulk elastic stripe period. We also simulate a rich variety of non-equilibrium patterns, influenced by size-dependent spinodal points and electro-autocatalytic control of thermodynamic stability.

磷酸铁锂（LiFePO ₄）是典型的两相电池材料，其复杂的锂离子嵌入模式为电化学热力学理论提供了测试基础。使用由法拉第反应驱动的相干相干的深度平均（ab平面）相场模型，我们可以将微米级血小板中类金刚石相图案的相互矛盾的实验观察结果与纳米颗粒中的表面可控模式观察结果进行协调。弹性分析预测a轴尺寸超过整体弹性条纹周期两倍的粒子的这种形态转变。我们还模拟了多种非平衡模式，受大小相关的旋节点和热力学稳定性的电自动催化控制的影响。