Supercooled Liquids in a Core-Shell Coordination Structure for Practical Long-Term Energy Storage.

Abstract

Mutual acquisition of phase-stability and controllable phase-transition becomes a predominant criterion of phase-change materials for the practical long-term energy storage but seems contradictory always. Here a strategy combining coordination and hydrogen bonds hierarchically to create a supercooled liquid in a core-shell coordination structure is reported, addressing that demand successfully. This new material is composed of a Mn-methylurea complex (MM) core and the hierarchically bonded erythritols shell. MM glass core with a viscosity of 10⁸ Pa·s determines its thermal phase-stability. As discovered, the ingenious ligand-exchange between erythritol and Cl^- ion coordinated with MM core accounts for this effectively reversible phase-transition. This can be triggered by a small shear-stress of 10 Pa within tens of seconds, exhibiting good practicability. Thermodynamics and kinetics of phase-transition are explored.