The use of phase change materials (PCMs) for solar thermal collection can solve the mismatch problem of energy supply and demand caused by intermittent solar radiation. Traditionally, photo-thermal storage performance has been limited by the low thermal conductivity of PCMs and the massive heat transfer loss between PCMs and their external environment. Herein, we demonstrate that embedding a highly oriented graphite sheet (GS) network in a PCM results in an anisotropic thermal conduction structure, endowing the material with rapid internal thermal conduction and reduced heat loss to the external environment, thereby enhancing photo-thermal storage performance. We imitate the structure of layer cake to create a multilayered composite phase change material (CPCM), Mg(NO₃)₂∙6H₂O/g-C₃N₄-GS (MNH/CN-GS), which has a highly oriented anisotropic thermal conductivity. The through-plane and in-plane thermal conductivities of MNH/CN-GS reach 0.55 and 15.70 W/(m·K), respectively, at 40 wt% GS loading in the CN-GS matrix. This corresponds to a high anisotropic degree of thermal conduction of 28.56, which results in a high average photo-thermal storage efficiency of 88.4%. The photo-thermal storage efficiency remains above 80% even at a high temperature of approximately 94 ℃. The proposed anisotropic thermal conduction structure eliminates the trade-off between high photo-thermal conversion rate and high energy efficiency in solar thermal storage.

使用相变材料（PCMs）进行太阳能集热可以解决间歇性太阳辐射引起的能源供需不匹配问题。传统上，光热存储性能受到相变材料的低导热性以及相变材料与其外部环境之间大量的热传递损失的限制。在此，我们证明在 PCM 中嵌入高度取向的石墨片 (GS) 网络会产生各向异性的热传导结构，使材料具有快速的内部热传导并减少向外部环境的热损失，从而提高光热存储性能. 我们模仿层状蛋糕的结构创造了一种多层复合相变材料（CPCM），Mg(NO ₃ ) ₂ ∙6H₂ O/gC ₃ N ₄ -GS (MNH/CN-GS)，具有高度定向的各向异性热导率。在 CN-GS 基体中负载 40 wt% GS 时，MNH/CN-GS 的面内和面内热导率分别达到 0.55 和 15.70 W/(m·K)。这对应于 28.56 的高各向异性热传导度，这导致 88.4% 的高平均光热存储效率。即使在约94℃的高温下，光蓄热效率也保持在80%以上。所提出的各向异性导热结构消除了太阳能热存储中高光热转换率和高能效之间的权衡。