Mechanically and Thermally Guided, Honeycomb-like Nanocomposites with Strain-Insensitive High Thermal Conductivity for Stretchable Electronics

Thermal management materials have become increasingly crucial for stretchable electronic devices and systems. Drastically different from conventional thermally conductive materials, which are applied at static conditions, thermal management materials for stretchable electronics additionally require strain-insensitive thermal conductivity, as they generally undergo cyclic deformation. However, realizing such a property remains challenging mainly because conventional thermally conductive polymer composites generally lack a mechanically guided design. Here, we report a honeycomb-like nanocomposite with a three-dimensional (3D) thermally conductive network fabricated by an arrayed ice-templating technique followed by elastomer infiltration. The hexagonal honeycomb-like structure with thin, compact walls (≈ 40 μm) endows our composite with a high through-plane thermal conductivity (≈ 1.54 W m^-1 K^-1) at an ultralow boron nitride nanosheet (BNNS) loading (≈ 0.85 vol %), with an enhancement factor of thermal conductivity up to 820% and thermal-insensitive strain up to 200%, which are 2.7 and 2 times higher than those reported in the literature. We report an intelligent strategy for the development of advanced thermal management materials for high-performance stretchable electronics.