Performance-differentiated phase change sandwich composite with gradient thermal conductivity for transient thermal shock protection and multi-source thermal management

Effective thermal management is crucial for multifunctional applications and energy efficiency, yet phase change materials (PCMs) are often limited by the fixed thermal conductivity in dynamic environments. We proposed a novel sandwich-structured composite based on composite phase change materials (CPCMs) with gradient thermal conductivities. This layered design uniquely integrates an outer silica aerogel (SA)/PCM layer providing excellent thermal insulation and shock buffering, with an inner flake graphite (FG)/PCM layer ensuring rapid internal heat dissipation and temperature regulation. A middle pure aerogel layer provides thermal decoupling. N-octadecane/melamine formaldehyde resin microencapsulated phase change materials (MPCM) is incorporated as the core thermal storage component. Specifically, the SA/PCM-70 composite demonstrated an ultralow thermal conductivity of 0.0725 W·m −1 ·K −1 and a phase change enthalpy of 109 J·g −1 . In contrast, the FG/PCM-70 composite, achieved a high thermal conductivity of 1.752 W·m −1 ·K −1 (an 8-fold increase over pure MPCM) while retaining a significant latent heat of 111.3 J·g −1 , considering a balance between them for the sandwich application. Transient thermal shock and multidirectional non-uniform heat disturbance tests confirmed the exceptional thermal insulation and temperature regulation capabilities in complex environments, such as building envelopes requiring external heat rejection and internal temperature stabilization, or battery modules needing both normal operation heat dissipation and thermal runaway protection. Furthermore, tests based on real outdoor temperatures demonstrated that rooms equipped with the sandwich composite maintained more stable indoor temperatures, with a single-day maximum indoor temperature reduction of 3.15 °C than that using pure aerogel . These findings highlight the significant potential of the proposed sandwich-structured composite for advanced thermal management applications. • Phase change materials are integrated with silica aerogel and graphite to achieve tunable thermal conductivity . • Performance-differentiated sandwich composite prepared by the hot-pressing method. • The sandwich phase change material enables thermal shock protection and multi-source heat control simultaneously. • The sandwich composite improves indoor cooling efficiency by 3.2 °C than pure silica aerogel in summer.