In Situ Polymerized Composite Phase Change Materials with Dual-Enhanced Conductivity for Electrothermal Conversion

Electrothermal conversion and thermal energy storage represent a pivotal approach to mitigating the spatiotemporal mismatch between energy supply and demand. However, their advancement is constrained by critical issues such as phase change materials (PCMs) leakage and inadequate electrical and thermal conductivity. In response to the above issues, this study proposes an in situ fabrication strategy based on free radical polymerization: the phase change component, octadecyl acrylate (OA), is directly polymerized within a carbon fibers (CFs) array integrated with thermal fins–boron nitride@ nanodiamonds (BN@NDs). The axially continuous structure of the CFs ensures a high electrical conductivity exceeding 100 S/m in the composite PCM (CPCM). Meanwhile, the addition of BN@NDs increases the radial thermal conductivity from 0.52 to 1.67 W/(m·K). The CPCM exhibits a ΔH of 85.45 J/g and an electrothermal conversion efficiency of 78.45% under 5 V, providing new insights for the design of novel high-performance electrothermal PCMs.