Robust BNNS/ANF aerogel skeleton-based PEG composite phase change materials with high latent heat for efficient thermal management

In this work, PEG-based phase change materials with high latent heat were fabricated by integrating ANF with two-dimensional BNNS to create a robust hybrid aerogels skeleton with subsequent PEG impregnation. Specifically, BNNS was initially obtained by boric acid-assisted ball milling, and BNNS/ANF hybrid aerogels were then obtained by freeze-drying. The hybrid aerogel had pores uniformly distributed with a size range of 73–190 μm and exhibited a compressive strength of 28.1 kPa with 50 wt% BNNS. The BNNS/ANF porous skeletons were employed as packaging materials for PEG, offering not only a high-load environment and excellent mechanical support, but also outstanding thermal conductivity. The composite phase change material demonstrated a thermal conductivity of 0.48 W/m·K with 40 wt% BNNS, which was 200 % higher than that of pure PEG. In particular, the rigid BNNS/ANF hybrid aerogels skeleton facilitated PEG storage, achieving a maximum loading rate of 98.73 % and an enthalpy efficiency of 99.87 %, respectively. The phase change enthalpy of the composites was as high as 189.19 J/g. The rigid support and adsorption capabilities of the skeleton structure also improve the shape stability and cycle stability during phase transition. Even after 50 thermal cycles, the phase transition temperature and enthalpy of the composites remained largely unchanged.