Facile fabrication of NiCl2/g-C3N4 composite as high-performance cathode material for thermal battery

Abstract

The NiCl2 cathode material used in thermal batteries still encounters challenges such as poor compatibility with ternary electrolytes, high polarization internal resistance and long activation time, all of which hinder its widespread application. In this research, lamellar structure NiCl2/g-C3N4 cathode composites (NCCN) are prepared by the ball milling-calcination method. The triangular porous structure of graphitic carbon nitride (g-C3N4) promotes the specific surface area of the material and accelerates the transport of reactive particles. Meanwhile, the protective effect of g-C3N4 mitigates direct contact between NiCl2 and the ternary lithium electrolyte, improving the discharge compatibility of the battery. The attraction of free electrons by the pyridine nitrogen reduces the energy barrier for carrier transition from the valence band to the conduction band, thereby enhancing the conductivity of NiCl₂. The 5 wt.% g-C3N4-modified NiCl2 composite exhibits a high discharge capability, high-rate performance and a relatively short thermal activation time. At a cut-off voltage of 1.50 V and a current density of 300 mA cm−2, it achieves a specific capacity of 310.74 mAh g−1 and a high specific energy of 701.39 Wh kg−1. Furthermore, the thermal activation time of the 5 wt.% g-C3N4-modified NiCl2 composite was reduced by about 40% in comparison to that of pure NiCl2, which is of great significance for broadening the application of NiCl2-based cathode materials in the field of emergency equipment.