Construction of a hierarchical porous surface composite electrode by dynamic hydrogen bubble template electrodeposition for ultrahigh-performance thermally regenerative ammonia-based batteries

• Hierarchical porous Cu/Ni electrode was proposed for thermally regenerative battery. • Bubble template electrodeposition was used to create hierarchical pores on electrode. • Ultrahigh performance was observed in battery with hierarchical porous electrodes. • A bimetallic electrode system was further applied for the highest performance. Developing porous electrodes that have large surface area, low mass transfer resistance and stable structure for electrochemical reactions is extremely important for the performance improvement and future application of thermally regenerative ammonia-based batteries (TRABs). In this work, a multilayer Cu/Ni composite electrode with hierarchical porous surface is proposed for TRABs and prepared via three steps of electroplating including dynamic hydrogen bubble template (DHBT) electrodeposition method. It is demonstrated that this Cu/Ni composite electrode with high electrode area, hierarchical porous surface and high conductivity are beneficial for the electrochemical reaction and mass transport, hence an ultrahigh power density of TRAB. The maximum power density of TRAB using hierarchical porous surface Cu/Ni composite electrode (TRAB-P) is 102 Wm −2 , which is increased by 149% and 82% compared with that of TRABs with copper mesh and copper foam. Moreover, relative high performance in energy generation and stable discharging process are obtained in TRAB-P. Based on this novel electrode, a highest reported power density (1002 Wm −2 ) is obtained by applying a bimetallic electrode system. This indicated that the use of hierarchical porous surface composite electrodes is a promising choice for the operation of TRABs, especially in future applications.