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 10 8 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.