Pyrite thin films prepared for thermal batteries via sulfuring electrodeposited iron sulfide films: Structure and physical properties

• Theoretical formula was deduced to provide parameters for preparing pyrite films.
• Properties of pyrite film are discussed based on probable use in thermal battery.
• AFM is employed to investigate topography and grain distribution of pyrite film.
• TGA is imported to evaluate purity and thermal stability of pyrite film.
• Pyrite films exhibit high crystallinity, purity, thermal stability and activity areas.

In recent years, pyrite thin film has received considerable attentions in energy storage. But rare attentions have been dedicated to its possible application in thermal batteries. In this study, we synthesized pyrite films by sulfuring electrodeposited iron sulfide films at 773 K under dynamic sulfur atmosphere, and analyzed their physical properties for thermal battery use. To determine the sulfuring parameters, we fabricated for the first time a theoretical relationship of sulfur partial pressure, molar weight of sulfur, carrier gas flux and heating rate in dynamic system. The effect of annealing time on topography of films and grain distributions were investigated by atomic force microscopy (AFM). The purity and thermal stability were evaluated by thermal gravimetric analysis (TGA). Several superior physical properties make pyrite thin film an attractive cathode material for thermal batteries.