Biomimetic and Compressible Wood Phase Change Gel With Hierarchically Aligned Lamellar Structure for Controlled Thermal Management

ABSTRACT The recovery and utilization of ubiquitous low‐grade heat are crucial for mitigating the fossil energy crisis. However, uncontrolled spontaneous heat dissipation limits its practical application. Inspired by skeletal muscle thermogenesis, we develop a compressible wood phase change gel with mechano‐controlled heat release by infiltrating xylitol gel into wood aerogel. The xylitol gel can store recovered low‐grade heat for at least 1 month by leveraging its inherent energy barrier. The hierarchically aligned lamellar structure of wood aerogel facilitates mechanical adaptation, hydrogen bond formation, and energy dissipation between the wood aerogel and the xylitol gel, increasing the compressive strength and toughness of wood phase change gel fivefold compared to xylitol gel. This enhancement effect enables repetitive contact‐separation motions between the wood phase change gel and the substrate during radial compression, overcoming the energy barrier and releasing approximately 178.6 J g ⁻¹ of heat. As a proof‐of‐concept, the wood phase change gel serves as the hot side in a thermoelectric generator, providing about 2.13 W m ⁻² of clean electricity by the controlled utilization of recovered solar heat. This study presents a sustainable method to achieve off‐grid electricity generation through the controlled utilization of recovered low‐grade heat.