Discarded sericultural mulberry branch based triple layer composite phase change material with lignin enhanced thermal management capability.

With the exhaustion of fossil fuels, prior phase change materials are characterized by such drawbacks as poor thermal conductivity, weak shape stability, and high costs. Therefore, the preparation of phase change materials with brilliant thermal-insulating properties, high thermal conductivity, and leakage-free properties has emerged as a crucial research focus. Herein, a sericultural mulberry branch-derived (SMB) composite phase change material was prepared by deep eutectic solvent pretreated SMB and vacuum-assisted impregnated paraffin wax with cupric oxide (CuO). The anisotropic porous SMB features a whole trunk structure similar to pith, xylem, and bark, which is closely tied physiological functions and provides a foundation for thermal storage and release. Triple layer porous structure of SMB as supporting material determined the excellent shape stability of composite phase change material. The addition of CuO significantly enhances the thermal conduction capacity. After 50 cycles heating, CuO/PW/DSMB retained 98 % of latent heat capacity and enthalpy change for heat absorption was measured at 91.66 J/g, which represents a decrease of 17.94 J/g, demonstrating a significant superior latent thermal effect and excellent thermal stability. Moreover, the triple layer of SMB uneven thermal transfer generate a self-regulating thermal management functional structure to achieve mutual thermal compensation. In summary, this composite phase change material, with its excellent properties of thermal insulation, high thermal conductivity, leakage-free nature, low cost, and easy availability, has broad application prospects in thermal energy storage and energy conservation.