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In this paper, single-phase pyrite with different particle sizes is prepared by hydrothermal method with the reactants of NaS, S, and FeSO. Compared with natural pyrite powder, synthesized pyrite nanocubes with small particle sizes and fine distribution have lower resistance, higher specific capacity and power density during the discharging process. The enlarging contacting surface area of pyrite with electrolytes will reduce the concentration polarization caused by the discharging current and improve the utilization efficiency of the pyrite materials. When pulse currents are loaded, compared with natural pyrite single-cell thermal battery, synthetic ones have smaller voltage drops and higher power density during the pulse discharging process. Influences of particle sizes on the thermal stability of the pyrite powders have also been investigated. [ABSTRACT FROM AUTHOR]

This paper describes the synthesis and properties of the porous MgO fibers used as a binder of the electrolyte for thermal batteries. Porous MgO fibers with controlled pore size were prepared by a facile hydrothermal method in the presence of polyethylene glycol (PEG). The effect of PEG addition on the pore sizes of the porous MgO fibers was systematically investigated. The influence of porous MgO fibers having different pore sizes on the electrolyte (LiCl-KCl) leakage and electrochemical performances of the corresponding model cells were measured. The results show that a large amount of PEG leads to porous MgO fibers having high specific surface area and total pore volume, and reaching the maximum, 13.65 m 2 g −1 and 0.097 m 3 g −1 respectively, at 1.5 mol% of PEG addition. The model cell fabricated with porous MgO fiber having high surface area and pore volume shows low deformation and electrolyte leakage, as well as high discharge capacity. Electrochemical impedance spectroscopy (EIS) analysis shows that, the ionic conductivity of the cell increases as the porous MgO fiber pore size increasing. These performances are much better than the performances of cell fabricated with traditional MgO powders. The dimensional stability and large surface area contact of porous MgO fibers with molten electrolyte should account for the superior physical and electrochemical performances of model cell fabricated with porous MgO fibers. [ABSTRACT FROM AUTHOR]

In this study, MgO fibers were used to immobilize the molten electrolyte in thermal batteries, which replaced the current MgO powders. MgO fibers were synthesized via a facile hydrothermal method. Solvent concentration was found to influence the aspect ratio of MgO fiber regularly. A lower concentration led to a larger aspect ratio. The effects of fiber's aspect ratio on the electrolyte (LiCl-KCl) leakage, discharge properties, and ionic conductivity of model cell were evaluated. The higher the fiber aspect ratio was, the lower the molten electrolyte leakage was. The electrolyte leakage of pellet using fiber was obviously lower than that using powder. Moreover, during the discharge process, the cell using fiber maintained a longer discharge time than that using powder, while the ionic conductivities were very close. The well performance of MgO fiber-filled cell was due to its dimensional stability and large contact area with molten electrolyte, which was generated from low aggregation and similar net structure. [ABSTRACT FROM AUTHOR]

Cobalt disulfide (CoS 2 ) is a promising thermal battery electrode material for its superior thermal stability and discharge performance. However, the low natural resource and poor air stability restrict its application in thermal battery fabrication. In this work, carbon coated CoS 2 composite was prepared by a facile one-pot hydrothermal method with glucose as carbon source. During the growth of CoS 2 , the glucose molecules were in situ adsorbed and carbonized on the surface of the as-synthesized CoS 2 , and the resultant carbon coating provided improved electrical conductivity and discharge performances to the composite. The thermal battery cell, which was fabricated with such a composite cathode and with a Li-Si anode, can output a capacity of 235.8 mAh g −1 and an energy density of 416.9 Wh kg −1 at a cut-off voltage of 1.7 V. This carbon coated CoS 2 composite also presented enhanced air stability. After being stored in dry air for 3 months, the composite can still provide a capacity of 232.4 mAh g −1 to 1.7 V, whereas the capacity of bare CoS 2 stored with the same condition dropped from 202.4 mAh g −1 to 189.7 mAh g −1 . [ABSTRACT FROM AUTHOR]

CoS 2 /CNTs composites were prepared by a facile and simple hydrothermal growth of CoS 2 in the presence of carbon nanotubes (CNTs), as a novel approach of synthesizing cathode composites for thermal battery fabrication. The incorporation of CNTs in the CoS 2 cathode materials thus synthesized effectively improved the electrical conductivity and discharge performance of the resultant cathode, without significantly compromising its thermal stability. The thermal battery cell fabricated with such a composite cathode and with a common Li–Si anode showed all functional features of a proper thermal battery cell. The specific discharge capacity at a cut-off voltage of 1.7 V was 219.8 mA h g −1 , and the corresponding energy density was 387.2 W h kg −1 . With a pulse current density of 500 mA cm −2 , the battery delivered a pulse power of 2.45 W, and maintained 64% of this power after 30 pulses. Regarding thermal stability, the CoS 2 /CNTs cathode was stable at least at 625 °C. [ABSTRACT FROM AUTHOR]