Construction and application of biochar-based composite phase change materials

•Methods to enhance the performance of biochar-based composite PCMs are summarized.•The application scenarios of biochar-based composite PCMs are summarized.•Prospects for the future development of biochar-based composite PCMs are presented. Biomass-synthesized biochar has abundant pore structure, large specific surface area, and strong adsorption capacity. Phase change materials (PCMs) have obvious advantages in using clean energy and improving energy efficiency. Biochar-based composite PCMs use the abundant pore structure of the biochar to efficiently encapsulate PCMs, which not only achieve carbon sequestration but also have broad application prospects in the fields of solar energy usage, energy-saving buildings, and environmental temperature control. This review summarizes the synthesis of biochar and biochar-based composite PCMs in detail, as well as their application. Importantly, the prospect of biochar-based composite PCMs development is presented. This review will provide references for advancing the study of biochar-based composite PCMs, which are crucial for resource recycling, as well as green and low-carbon development.