Scalable Preparation and Improved Discharge Properties of FeS2@CoS2 Cathode Materials for High-Temperature Thermal Battery.

Long-time thermal batteries with high specific energy are crucial for improving the fast response ability of long-range weapons. Due to its high capacity, safety, and stability, the new sulfide cathode has attracted extensive attention. In this study, an FeS2@CoS2 composite cathode with a core-shell structure was prepared via a combination of hydrothermal and high-temperature vulcanization processes. The novel FeS2@CoS2 cathode not only delivers a high discharge voltage and output capacity, but also has high thermal stability and excellent conductivity. Benefiting from the synergistic effect of FeS2 and CoS2, the as-synthesized cathode yields a high specific capacity. At a large current density of 1 A/cm2, the utilization rate of FeS2@CoS2 cathode material can reach 72.33%, which is 8.23% higher than that of FeS2. Moreover, the maximum output capacity is up to 902 As/g, with a utilization rate of 79.02% at 500 mA/cm2. This novel design strategy holds great promise for the development and application of high-performance thermal batteries in the future.

Fabrication of the Ni-NiCl2 Composite Cathode Material for Fast-Response Thermal Batteries.

Thermal batteries with a high power density and rapid activation time are crucial for improving the fast response ability of sophisticated weapons. In this study, an Ni-NiCl2 composite was prepared via hydrogen reduction and employed as a cathode material. Discharge tests on a battery assembled using the fabricated composite revealed that its initial internal resistance decreased and the activation time reduced. Notably, the Ni-NiCl2 cathode increased the energy output by 47% (from 6.76 to 9.94 Wh in NiCl2 and Ni-NiCl2, respectively) with a cut-off voltage of 25 V; the power density of the novel battery system reached 11.4 kW/kg. The excellent performance of the thermal battery benefited from the high electrode potential and low internal resistance of Ni-NiCl2. This study contributes to the development of high-performance electrode materials for next-generation thermal battery-related technologies.

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

Transition-metal sulfides are key cathode materials for thermal batteries used in military applications. However, it is still a big challenge to prepare sulfides with good electronic conductivity and thermal stability. Herein, we rapidly synthesized a Co-doped NiS2 micro/nanostructure using a hydrothermal method. We found that the specific capacity of the Ni1-xCoxS2 micro/nanostructure increases with the amount of Co doping. Under a current density of 100 mA cm-2, the specific capacity of Ni0.5Co0.5S2 was about 1565.2 As g-1 (434.8 mAh g-1) with a cutoff voltage of 1.5 V. Owing to the small polarization impedance (5 mΩ), the pulse voltage reaches about 1.74 V under a pulse current of 2.5 A cm-2, 30 ms. Additionally, the discharge mechanism was proposed by analyzing the discharge product according to the anionic redox chemistry. Furthermore, a 3.9 kg full thermal battery is assembled based on the synthesized Ni0.5Co0.5S2 cathode materials. Notably, the full thermal battery discharges at a current density of 100 mA cm-2, with an operating time of about 4000 s, enabling a high specific energy density of around 142.5 Wh kg-1. In summary, this work presents an effective cathode material for thermal battery with high specific energy and long operating life.

A Solution-based Method for Synthesizing Pyrite-type Ferrous Metal Sulfide Microspheres with Efficient OER Activity.

Simple and stable synthesis of transition metal sulfides and clarification of their growth mechanisms are of great importance for developing catalysts, metal-air batteries and other technologies. In this work, we developed a one-step facile hydrothermal approach to successfully synthesize NiS2 microspheres. By changing the experimental parameters, the reason that affects the formation of nanostructured spheres is investigated and discussed in detail, and the formation mechanism of microspheres is proposed innovatively. Furthermore, electrochemical testing results show that the 7 h-NiS2 catalyst exhibits a remarkable oxygen evolution reaction (OER) activity with an overpotential of 311 mV at 10 mA cm-2 in 1.0 M KOH, superior to precious metal RuO2 . The NiS2 catalyst also exhibits a robust durability. This work will contributes to the rational design and the understanding of growth mechanism of transition metal chalcogenide electrocatalysts for diverse energy conversion technologies.