Enhancing flexible thermoelectric conversion by efficient interfacial heat conduction via synergistic effect of highly thermally conductive graphite sheets and highly adhesive hydrogels

Developing advanced thermal interface materials (TIMs) with high adhesion and high thermal conductivity is of fundamental and strategic significance for improving the heat conduction and operational efficiency of flexible thermoelectric conversion devices. However, at present, it is difficult to achieve both high adhesion and high thermal conductivity when constructing an integrated flexible thermoelectric conversion device. Here, we report a strategy to enhance the flexible thermoelectric conversion by utilizing the synergistic effect of highly thermally conductive graphite sheets and highly adhesive hydrogels. A highly adhesive hydrogel with an adhesion strength as high as 102.67 kPa was prepared using a physical-chemical crosslinking method. Graphite sheets with high in-plane and inter-plane thermal conductivity (144.54 W·m −1 ·K −1 and 17.85 W·m −1 ·K −1 , respectively) were designed using interface modification and cold pressing processes. Janus-type TIMs are constructed based on multiple interactions between modified graphite sheets and adhesive hydrogels. The adhesion strength and effective thermal conductivity of these TIMs are as high as 36.16 kPa and 1.80 W·m −1 ·K −1 , respectively. Finally, the integrated assembly of Janus-type TIMs and thermoelectric materials enhances flexible thermoelectric conversion. This work achieves an effective synergy between high adhesion and high thermal conductivity through a Janus-type multilevel structure, providing theoretical guidance for efficient and stable TIMs.