Supramolecularly Anchored Skeleton‐Intrinsic Phase‐Change Monoliths Enabling Passive Thermal Homeostasis of Outdoor Electronics

ABSTRACT Mitigating extreme temperature fluctuations is critical for maintaining data integrity and preventing failure in outdoor electronics. However, durable passive thermal homeostasis for such electronics under fluctuating outdoor conditions remains challenging. Here, we report a skeleton‐intrinsic phase‐change monolith (SPCM) fabricated through supramolecular anchoring. A noncovalent supramolecular network robustly confines molten phase‐change domains within a load‐bearing skeleton, combining a high latent‐heat capacity of 125 J g −1 with an ultralow thermal conductivity of 0.027 W m −1 K −1 . The monolith retains 99% of its mass after 100 thermal cycles and remains leak‐free under 50% compressive strain. By integrating thermal insulation, latent‐heat buffering, and radiative heat dissipation, SPCM protects electronic devices against external thermal shocks. An SPCM‐packaged electronic device exhibits a temperature variation of less than 1.5°C when exposed to a 120°C heat source, compared with approximately 25°C for an unprotected device. The monolith also largely retains its phase‐change behavior, thermal insulation performance, and spectral selectivity after thermal cycling and environmental exposure, demonstrating stability under the tested harsh conditions. This work establishes a supramolecular skeleton‐engineering strategy for passive thermal management of electronics in fluctuating outdoor environments.