Waste heat management holds great promise to create a sustainable and energy-efficient society as well as contributes to the alleviation of global warming. Harvesting and converting this waste heat in order to improve the efficiency is a major challenge. Here we report biomimetic nacre-like hydroxyl-functionalized boron nitride (BN)-polyimide (PI) nanocomposite membranes as efficient 2D in-plane heat conductor to dissipate and convert waste heat at high temperature. The hierarchically layered nanostructured membrane with oriented BN nanosheets gives rise to a very large anisotropy in heat transport properties, with a high in-plane thermal conductivity (TC) of 51 W m⁻¹ K⁻¹ at a temperature of ∼300 °C, 7314% higher than that of the pure polymer. The membrane also exhibits superior thermal stability and fire resistance, enabling its workability in a hot environment. In addition to cooling conventional exothermic electronics, the large TC enables the membrane as a thin and 2D anisotropic heat sink to generate a large temperature gradient in a thermoelectric module (ΔT = 23 °C) through effective heat diffusion on the cold side under 220 °C heating. The waste heat under high temperature is therefore efficiently harvested and converted to power electronics, thus saving more thermal energy by largely decreasing consumption.

废热管理对建立可持续发展和高能效的社会具有巨大的希望，并有助于减轻全球变暖。收集和转化这些废热以提高效率是一项重大挑战。在这里，我们报告仿生珍珠母般的羟基官能化氮化硼（BN）-聚酰亚胺（PI）纳米复合膜作为有效的2D平面内导热体，可以在高温下消散和转化废热。具有定向BN纳米片的分层纳米结构化膜在传热性能方面具有非常大的各向异性，且面内热导率（TC）为51 W m ^-1  K ^-1在约300°C的温度下，比纯聚合物的温度高7314％。该膜还具有出色的热稳定性和耐火性，从而使其在高温环境下仍可使用。除了冷却常规的放热电子器件外，大的TC还可以使薄膜作为薄的2D各向异性散热器，通过在220°C下在冷侧有效地散热，从而在热电模块中产生较大的温度梯度（ΔT= 23°C）。 C加热。因此，可以有效地收集高温下的废热并将其转化为电力电子设备，从而通过大大减少能耗来节省更多的热能。