Synthesis Of CoS₂and Preparation Of Thin-film Electrode For Thermal Battery

With the emergence of new technology weapons, the rapid development of militaryindustry puts forward higher demands for the performances of thermal battery,especially hopes for the thermal battery with high power and energy output capability atthe same time. At the moment, the most commonly used cathode material for thermalbattery is FeS₂, but some shortcomings of itself restrict its application in thermal batteryseverely. CoS₂with high power and energy output capability at the same timeovercomes the inherent defects of FeS₂, making it become a kind of ideal cathodematerial which can replace FeS₂. Besides, the current preparation process for thermalbattery is pressed-powder, which has many disadvantages including strict ambientrequirements （relative humidity less than3%）, complex preparation process and lowutilization of active material. These disadvantages not only limit the large-scaleproduction of thermal battery but also damage the performances of thermal battery.Therefore, firstly due to the disadvantages of preparation methods for the thermalbattery cathode material CoS₂, CoS₂materiales were synthesized by hydrothermalprocess, and the effects of reaction temperature, reaction time, reactant concentration,the amount of EDTA-2Na and pH on the properties of CoS₂were discussed by using thetechniques of XRD, SEM, laser particle size analyzer, specific surface area/aperturetester and differential thermal analyzer. Next, due to the shortcomings of the currentpreparation process for single cell, the thin-film cathodes were prepared by screenprinting thin-film process. The addition levels of electrolyte and conductive agent inthin-film cathodes were studied, which are the major factors influencing on thedischarge performances of single cells. Finally, CoS₂thin-film cathodes were preparedby screen printing thin-film process. The conclusions are as follows:（1） High purity CoS₂materiales were prepared by hydrothermal process. Theoptimum conditions for preparing CoS₂materiales: heating temperature of180℃,heating time of24h, molar ratio of1:2:0.5of CoSO₄·7H₂O:Na₂S₂O₃·5H₂O:EDTA-2Na.The CoS₂with hollow sphere-like, block and flake-like morphologies were preparedunder different pH values. The block and flake-like samples have the larger specific surface area and higher decomposition temperature, which are helpful for high powerand energy discharge of their single cells.（2） Screen printing thin-film process can be operated under normal circumstances.Its preparation process is simple and can be large-scale production. The optimal additivequalities of electrolyte and conductor in thin-film cathodes are20wt%and3wt%. Inaddition the discharge temperature is a relatively sensitive factor for thermal batteries,the large current discharge performance is very poor when temperature is less than400℃. Compared with the traditional cold pressing of powder process, the single cellprepared by screen printing thin-film process have smaller internal resistance and betterlarge current discharge performance.（3） The CoS₂thin-film cathodes were prepared by screen printing thin-film processand assembled into single cells for discharge tests. Compared with the hollowsphere-like CoS₂material, the single cells which are prepared using the block andflake-like samples have better discharge performances when the large current discharge.So the block and flake-like samples are more suitable for the preparation of high powerthermal batteries.