Preparation Of Transition Metal Disulfides And Its Application In Thermal Batteries

Thermal battery is made of molten salt as electrolyte,using the internal heat source to make the battery reach the working temperature,so as to achieve high power discharge capacity.The thermal battery is mainly composed of cathode material,electrolyte,anode material,fluid collection and heat source,because the electrolyte at room temperature is a solid and non-conductive.However,liquid state has a very high conductivity,and the node material is lithium alloy material,so the thermal battery has the advantages of high specific energy,high specific capacity,long storage time,reliable operation,simple preparation technology and maintenance free.It is commonly used in the military fields,aerospace fields and as an emergency backup power source,such as emergency ejection seats for aircraft and fire alarm systems.With the deepening of the exploration of unknown fields and the development of national defense,the thermal battery is in an increasingly irreplaceable position.The most important component of thermal battery is cathode material,the performance of a thermal battery often depends on the cathode material.The most commonly used cathode material is transition metal sulfide.Thermal batteries using FeS₂ as cathode material have been widely used in various fields due to their abundant resources and good comprehensive performance.However,there are still many defects in sulfide cathode materials,such as poor thermal stability or low voltage platform,and the preparation of new cathode materials is often difficult or the synthesis cost is high.Therefore,it is necessary to modify sulfide cathode material to improve the electrochemical performance of thermal battery.This thesis is committed to realizing the modification of sulfide cathode materials.We use efficient and green synthesis method to prepare better performance of cathode materials for thermal batteries,and explore its electrochemical performance.Specific work is as follows:（1）NiS₂,CoS₂ and CoS₂@C were synthesized by hydrothermal method,and the electrochemical performance of single batteries using the synthesized nanomaterials as cathode materials was explored and compared.The specific capacity of CoS₂ cathode material is 552.5 m Ah·g^-1,which is larger than that of NiS₂ cathode material(542.7m Ah·g^-1).After the introduction of C element,the specific capacity of the single battery using CoS₂@C as the cathode material is 572.7 m Ah·g^-1,and the single battery has a more stable pulse discharge curve.（2）Ni-Co compound sulfide was synthesized by hydrothermal method.The single thermal cell using the cathode material was measured by constant current discharge test and pulse discharge test.When the cut-off voltage is 0.5 V,the single battery with C1（add 10%Co element）cathode material has the best discharge performance and the specific capacity(528.9 m Ah·g^-1)higher than the single battery with pure NiS₂ cathode material(489.9 m Ah·g^-1).（3）The FeS₂@Al₂O₃ material was synthesized by liquid phase method and high temperature sintering method to improve the wettability of cathode material.It was found that the specific capacity of FeS₂ with 3 wt%Al₂O₃ nanoparticles as cathode material is 341.3 m Ah·g^-1,which is higher than that of pure FeS₂ cathode material(319.7 m Ah·g^-1)under the same conditions.At the same time,a small amount of Al₂O₃nanoparticles were added to modify the FeS₂ cathode material,which can reduce the polarization phenomenon and improve the discharge stability of thermal battery effectively.In this thesis,there are 38 figures,6 tables and 115 reference articles.