Atomistic Origin of the High Supercooling of Erythritol for Seasonal Thermal Energy Storage: Decoupling Thermodynamic and Kinetic Barriers for Crystallization

Crystallization from supercooled liquids is a scientific challenge across diverse disciplines. For seasonal thermal energy storage (TES), erythritol is a promising phase change material (PCM) due to its high natural degree of supercooling. However, successfully suppressing its spontaneous crystallization under extreme climates requires a fundamental understanding of the underlying nucleation and crystal growth mechanisms of such PCMs. Here, the thermodynamic and kinetic barriers governing the supercooled state of erythritol are systematically decoupled at the atomic scale. It is revealed that the suppression of crystallization relies on a highly synergistic “dual-locking” mechanism, characterized by a decoupling gap of ∼70 K between the maximum crystal growth rate and the maximum steady-state nucleation rate. Specifically, at low degrees of supercooling, spontaneous nucleation is thermodynamically suppressed by a massive solid–liquid interfacial entropy penalty, which induces an insurmountable critical nucleation barrier. Liquid molecules must sacrifice substantial conformational degrees of freedom to match the crystal lattice, quantified by a significant conformational entropy gap of approximately 9–10 J/(mol·K). In contrast, at high degrees of supercooling, while the critical nucleation barrier sharply diminishes to theoretically facilitate nucleation, the stabilization transitions to an extreme kinetic lock. It is demonstrated that interconnected cooperative hydrogen bond networks induce severe global dynamical arrest. This mechanism exponentially stretches the structural relaxation time to the microsecond time scale, essentially paralyzing molecular diffusion and plummeting crystal growth rate by orders of magnitude. This decoupled microscopic insight provides a targeted theoretical foundation for the rational design of PCMs with ultrahigh supercooling for future long-duration TES applications.