A new strategy for balancing thermal stability and latent heat of solid–liquid PCMs via a solid–solid PCM as a supporting skeleton

Abstract

Insufficient thermal stability of phase change materials (PCMs) remains a fundamental limitation for next-generation battery thermal management. Here, we present a low-temperature skeleton-engineering strategy to construct a three-dimensional solid–solid phase change polymer (SSPCM) that immobilizes a solid–liquid PCM, yielding a composite PCM (CPCM) with exceptional thermal stability and application versatility. The SSPCM was formed by in situ free-radical copolymerization of stearyl acrylate (SA) and hexamethylene diacrylate (HA) as monomers within a paraffin matrix, using a redox initiation system. This process proceeds under mild conditions (as low as 40 °C), without requiring high temperature, pressure, or sealed environments, enabling a scalable and energy-efficient fabrication route. The resulting CPCM exhibits remarkable thermal stability, with a mass loss of only 0.35 wt% after 120 h at 55 °C (above its phase transition temperature), and retains structural integrity up to 250 °C. It also delivers a high latent heat of 112.02 J g⁻¹ and a thermal conductivity of 2.36 W m⁻¹ K⁻¹. When applied in lithium-ion battery modules, it significantly suppresses temperature rise, limiting the peak temperature to 49.1 °C and the temperature gradient to 1.82 °C under 2C discharge. This work offers a scalable, low-energy fabrication route to structurally stabilized PCMs, enabling multifunctional thermal management solutions in both energy storage and broader thermal control applications.