Shape-stabilized and antibacterial composite phase change materials based on wood-based cellulose micro-framework, erythritol-urea or erythritol-thiourea for thermal energy storage

The excellent shape-stabilized composite phase change material (PCM) with high phase change enthalpy plays a very important role in thermal energy storage and solar energy utilization. In this work, different proportions of erythritol-urea (E-U) and erythritol-thiourea (E-T) incorporated into the cellulose skeleton retention of paulownia chip (DPW) have been conducted to obtain biomass-based PCMs (EU-DPW, ET-DPW). The SEM analysis results show that DPW has a rich honeycomb pore structure, which can achieve high loading of erythritol-urea and erythritol-thiourea. The E7U3-DPW and E7T3-DPW composite materials obtained at the optimal ratio of E-U and E-T show high phase change enthalpies of 232.2 J/g and 273.3 J/g. The higher phase change enthalpy of E7T3-DPW is due to the higher phase change energy storage performance of E7T3 compound itself, the better compatibility between E7T3 and DPW, and the higher loading capacity of E7T3 in DPW. In addition, high light-to-heat conversion efficiency is considered to be a key factor for converting light energy into heat energy to realize energy storage applications. E7U3-DPW and E7T3-DPW can provide excellent light-thermal conversion efficiencies of 72.6% and 75.8%, respectively. E7U3-DPW and E7T3-DPW show good antibacterial properties against E. coli and S. aureus. After 100 heating–cooling cycles, the DSC curves and phase transition enthalpies of E7U3-DPW and E7T3-DPW remained almost unchanged, maintaining good thermophysical properties, and the structure of characteristic functional groups remained almost unchanged, maintaining good chemical stability, which shows great potential in medium-temperature solar energy and thermal energy harvesting in the field of antibacterial and thermal insulation.