Thermostable Nickel Chloride Film as High Specific Power Cathode for Thermal Battery

Film components have been progressively included in thermal battery due to their unique volume and performance superiority. With poor thermal stability, organic adhesives in film will decompose at operation temperature, generating gas within the battery shell. Considering structural integrity, organic adhesives in film components cannot be completely eliminated in prior reports. This research proposes a type of remarkable thermostable film cathode. Nickel chloride (NiCl₂) film cathode is fabricated using poly(vinylidene fluoride) (PVDF) and sodium silicate (Na₂SiO₃) as adhesives by tape-casting, densification, and heat treatment processes. The compact and tight structure of raw NiCl₂ film is obtained in densification process. Active materials loading can be tailored. After heat treatment, the thermostability of NiCl₂ film can be maintained well until 551 °C caused by thorough disintegration of organic adhesives. NiCl₂ film shows excellent mechanical properties derived from the exceptional binding effect of Na₂SiO₃. In thermal battery, NiCl₂ film exhibits the superior voltage platform, achieving an exceptional specific power of 31.24 kW kg^-1, which is 2.0 times greater than that of NiCl₂ tablet. Due to the short ion transport distance, NiCl₂ film demonstrates the higher ion diffusion coefficient at the late stage of discharge. This work provides an effect design strategy for film electrodes and film components operating under high-temperature conditions.