Eutectic Diol‐Acid Phase Change Composite Reinforced With Expanded Graphite for High Performance Thermal Management

A bio‐based binary eutectic phase change material (PCM) composed of 1,10‐decanediol (DDL) and sebacic acid (SEA) was developed for passive thermal management of electronic devices. The eutectic composition was optimized through theoretical calculations and experimental validation to achieve a high latent heat. Expanded graphite (EG) was incorporated as a highly conductive supporting matrix to fabricate DDL–SEA/EG composite PCMs (CPCMs). The thermophysical properties, shape stability, thermal cycling reliability, and thermal management performance of the CPCMs were systematically evaluated. Results demonstrate that the CPCM with 12 wt% EG achieves a thermal conductivity of 9.305 W·m ⁻¹ ·K ⁻¹ (16.5‐fold enhancement) and a latent heat of 194.1 kJ·kg ⁻¹ , while maintaining high shape stability with negligible leakage. Furthermore, the CPCM retains 98.5% and 99.6% of its initial melting and solidification enthalpy after 200 thermal cycles. Thermal management tests using a simulated electronic heat source reveal that the DDL–SEA/EG CPCM prolongs the time to reach 80 °C from 285 to 1400 s (a 391% increase) and suppresses the steady‐state operating temperature by 10.3 °C. These findings indicate that the DDL–SEA/EG CPCM effectively resolves the tradeoff between energy storage capacity and thermal conductivity, presenting a highly promising, sustainable material for advanced passive electronics thermal management.