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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]

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]