A Wood Plasticine With Controlled Phase‐Change Behavior and Malleability for Energy‐Closed‐Loop and Conformally Adaptive Thermal Management

ABSTRACT Solar heating enables energy conservation and carbon mitigation. However, this heating method struggles with the spontaneous heat loss, geometrically diverse heat‐demanding objects, and inefficient interfacial heat transfer. Herein, we fabricate a wood plasticine with controlled phase‐change and malleable characteristics, achieved through the synergistic effects of molecular‐scale and nano/micro‐scale hydrogen bonding networks. The supercooled wood plasticine enables stable room‐temperature solar heat storage for 48 h, owing to a raised nucleation energy barrier resulting from molecular‐scale hydrogen bonding networks between erythritol and glycerol. Through a force‐induced supercooling‐crystallization phase change, the wood plasticine can controllably release 108 J g ⁻¹ of stored solar heat. The wood‐derived cellulose dispersed in erythritol and glycerol enables the formation of nano/micro‐scale hydrogen bonding networks. The synergy between glycerol's fluidity and the spatial confinement of cellulose fibers enables the reversible disruption and reconstruction of multiscale hydrogen bonding networks under external pressure. Driven by this dynamic property, the wood plasticine achieves conformal contact with geometrically diverse heat‐demanding objects, reducing contact thermal resistance by 28.7%. An energy‐closed‐loop system based on a harvest‐storage‐release mechanism utilizing wood plasticine is conceptually demonstrated to enable versatile applications, such as thermoelectric conversion and battery/personal thermal management, providing a new paradigm for on‐demand and low‐loss solar heating.