Carbonized flowery carbon derived from lignin for efficient heat to current conversion of low-grade heat

The urgent demand for stable, consistent, eco-friendly, and reliable power sources ultimately promotes the creation of new green energy materials. Due to their singular capacity of achieving efficient energy conversion between heat and power, nanoporous carbon-based thermally chargeable supercapacitors (TCS) have drawn interest due to their multiple applications in gathering of low-grade and waste heat. High-performance TCS is significantly influenced by the amount of active surface area and distribution of pore sizes of the electrode materials. Herein, the optimized porous flowery carbon made from enzymatic lignin has a high specific surface area of up to 897 m 2 g −1 , which gives it a promising thermal charging performance and the superior capacity to accommodate a large number of ions. With a temperature differential of 45 °C (K), the TCS using this carbonized flowery lignin electrode is capable of producing an open-circuit voltage of 513 mV with a Seebeck coefficient as high as 11.40 mV K −1 . This work not only demonstrates the applicability of carbonized lignin as an advanced material for energy applications but it also offers a fresh viewpoint on the advancement of TCS.