Ceramic powder, such as MgO, is added as a binder to prepare the green compacts of molten salts of an electrolyte for a thermal battery. Despite the addition of a binder, when the thickness of the electrolyte decreases to improve the battery performance, the problem with the unintentional short circuit between the anode and cathode still remains. To improve the current powder molding method, a new type of electrolyte separator with porous MgO preforms is prepared and characteristics of the thermal battery are evaluated. A Spherical PMMA polymer powder is added as a pore-forming agent in the MgO powder, and an organic binder is used to prepare slurry appropriate for tape casting. A porous MgO preform with 300 μm thickness is prepared through a binder burnout and sintering process. The particle size of the starting MgO powder has an effect, not on the porosity of the porous MgO preform, but on the battery characteristics. The porosity of the porous MgO preforms is controlled from 60 to 75% using a pore-forming agent. The batteries prepared using various porosities of preforms show a performance equal to or higher than that of the pellet-shaped battery prepared by the conventional powder molding method.

The effects of particle size of Li-Si alloy and LiCl-KCl addition as a binder phase for raw material of anode were investigated on the formability of the thermal battery anode. The formability was evaluated with respect to filling density, tap density, compaction density, spring-back and compressive strength. With increasing particle size of Li-Si alloy powder, densities increased while spring-back and compressive strength decreased. Since the small spring-back is beneficial to avoiding breakage of pressed compacts, larger particles might be more suitable for anode forming. The increasing amount of LiCl-KCl binder phase contributed to reducing spring-back, improving the formability of anode powder too. The control of particle size also seems to be helpful to get double pressed pellets, which consisted of two layer of anode and electrolyte.

FeS₂ has been widely used for cathode materials in thermal battery because of its high stability and current capability at high operation temperature. Salts such as a LiCl-KCl were added as a binder for improving electrical performance and formability of FeS₂ cathode powder. In this study, the effects of the addition of Li₂O in LiCl-KCl binder on the formability of FeS₂ powder compact were investigated. With the increasing amount of Li₂O addition to LiCl-KCl binder salts, the strength of the pressed compacts increased considerably when the powder mixture were pre-heat-treated above 350°C. The heat-treatment resulted in promoting the coating coverage of FeS₂ particles by the salts as Li₂O was added. The observed coating as Li₂O addition might be attributed to the enhanced wettability of the salt rather than its reduced melting temperature. The high strength of compacts by the Li₂O addition and pre-heat-treatment could improve the formability of FeS₂ raw materials.

Citations

Citations to this article as recorded by  

• Effects of Particle Size and Binder Phase Addition on Formability of Li-Si Alloy Powder for Thermal Battery Anode
  Sung-Soo Ryu, Hui-Sik Kim, Seongwon Kim, Hyung-Tae Kim, Hae-Won Cheong, Sung-Min Lee
  Journal of Korean Powder Metallurgy Institute.2014; 21(5): 331.     CrossRef