Biomass waste-derived hierarchical porous composite electrodes for high-performance thermally regenerative ammonia-based batteries

Thermally regenerative ammonia-based battery (TRAB) is an electrochemical device for converting low-grade waste heat into electrical energy. To improve the power generation of TRAB, the biomass waste-derived hierarchical porous composite electrode is prepared through the corrosion method and the electroplating for the high specific surface area for electrochemical reactions and the hierarchical porous structure for mass transfer in this study. The use of the hierarchical porous composite electrodes induced a 77.4% higher maximum power density of TRAB (81.6 W m−2) compared with that of TRAB with copper foam electrodes (46.0 W m−2). As to the electrode preparation, the composite electrode structure is jointly influenced by the ratio of KOH and fungus bran pre-carbonized products (FBPC) and the electrodeposition time, affecting the battery performance. The optimal ratio of the KOH/FBPC and the optimal electrodeposition time are 1.0 and 20 min, respectively. In addition, the porous composite electrode is also applicable for bimetallic thermally regenerative ammonia-based batteries, in which the highest reported power density (848.2 W m−2) is obtained.