The Engineering Strategy in Fabrication and Application of High-Specific-Energy Cathode for Thermal Battery

Nickel chloride is a promising material as cathode candidate for thermal battery, attributed to its superior electrochemical performance including high operating voltage and high specific energy. However, high polarization and structural collapse have emerged as major challenge hindering the practical application of NiCl2 cathode. Herein we propose an engineering strategy to construct a high-specific-energy NiCl2-based cathode with rhombohedral structure and amorphous carbon-layer skin structure. Benefited from delicate structural characteristic and improved electrochemical activity, the cathode designed remarkably elevates the plateau voltage of a single cell to 2.5 V and achieves, for the first time, a specific energy of 266.5 Wh/kg at current density of 600 mA/cm2 in the thermal battery tests. Notably, in contrast to the lab-level methods, this engineering strategy is an industrially feasible approach to manufacture NiCl2-based cathode for expanded application in thermal battery. This strategy also provides new insight into the design of high-performance cathode.