Binder-Free Cathode for Thermal Batteries Fabricated Using FeS2 Treated Metal Foam

Abstract

In this study, we fabricated a cathode with lower amounts of additive materials and higher amounts of active materials than those of a conventional cathode. A thermal battery was fabricated using FeS 2 treated foam as the cathode frame, and its feasibility was verified. X-ray diffraction, transmission electron microscopy, and scanning electron microscopy were used to analyze the effects of thermal sulfidation temperature (400 and 500 • C) on the structure and surface morphology of the FeS 2 foam. The optimal temperature for the fabrication of the FeS x treated foam was determined to be 500 • C. The FeS 2 treated foam reduced the interfacial resistance and improved the mechanical strength of the cathode. The discharge capacity of the thermal battery using the FeS 2 treated foam was about 1.3 times higher than that of a thermal battery using pure Fe metal foam.

Cobalt-Doped NiS2 Micro/Nanostructures with Complete Solid Solubility as High-Performance Cathode Materials for Actual High-Specific-Energy Thermal Batteries

“…Consequently, such properties are valuable for military applications including missiles, ammunition, torpedoes, aircraft ejection seats, and nuclear weapons. − Generally, thermal batteries use FeS 2 as the cathode material due to its semiconductor characteristics, affordability, and high capacity properties. However, its application is limited because it self-discharges severely at low currents and decomposes to Fe 7 S 8 and S 2 at 550 °C. − On the other hand, CoS 2 exhibits remarkable discharge performance and outstanding thermal stability (it decomposes at 650 °C); thus, thermal batteries incorporating CoS 2 as a cathode material have enhanced discharge properties. − Apart from FeS 2 and CoS 2 , NiS 2 , which is also a sulfide of group VIII transition metals, has received great attention recently due to its large first platform theoretical specific capacity according to the Faraday equation − In comparison, the discharge capacity is higher than the first platform theoretical discharge capacity of FeS 2 (1206 As g –1 ) . Therefore, the integration of CoS 2 into NiS 2 promises a higher discharge capacity.…”

“…With the limitation of halogen molten salt electrolytes, sulfide systems are commonly applied in thermal batteries. − Specifically, MoS 2 and WS 2 transition-metal sulfides, whose thermal decomposition temperatures are well beyond those of 3d orbital transition-metal sulfides, have been developed for cathode materials. , However, due to the inclusion of a 4d or 5d orbital element, its discharge voltage is generally low, which limits the specific energy of the battery. For a thermal battery to supply power to a missile, a high precision discharge of 70–75% of the platform’s peak voltage is required. ,− Thus, much effort has been devoted to developing a high-performance cathode with a larger specific capacity via optimizing electrode preparation methods or designing new cathode materials. ,,− …”

In Situ Fabrication of NiS2 Nanoparticle-Coated g-C3N4 as a Cathode for Enhanced Lithium Thermal Battery Performance

“…(a) Discharge specific capacity of 2NCN and 5NCN samples at 100 mA cm –2 at 500 °C; (b) discharge capacity of the 5NCN sample at 50, 100, 300, and 500 mA cm –2 at 500 °C; (c) discharge capacity of the 5NCN sample at 100 mA cm –2 at 450, 475, 500, and 525 °C; (d) comparison of the specific capacity and peak voltage of different cathode materials for Li thermal batteries reported in the literature; ,,− (e) pulse discharge curve and internal resistance of 2NCN and 5NCN with a pulse current density of 300 mA cm –2 for 2 s every 30 s under a constant current density of 100 mA cm –2 ; (f) EIS curves of 2NCN and 5NCN electrodes.…”

Recent Developments of Cathode Materials for Thermal Batteries

“…Such method can be easily scaled up, but increases the internal resistance of the battery due to the presence of different polymer binders ( Masset et al, 2005 ; Cha et al, 2018 ). Various studies shows the phase transformations of FeS 2 discharging process as follows ( Tomczuk et al, 1982 ; Choi et al, 2014 ; Chen et al, 2017 ; Cha et al, 2018 ; Zhang and Tran, 2018 ; Kim et al, 2020 ; Zou et al, 2020 ; Thu et al, 2021 ): FeS 2 →Li 3 Fe 2 S 4 →Li 2+x Fe 1-x S 2 →Fe.…”