Preparation And Discharge Performance Of Nickel-based Cathode Materials For Thermal Batteries

As a special kind of special military battery,thermal battery is widely used in military weapons due to its unique structural characteristics,and its development has been widely concerned by scientific researchers from all over the world.Compared with the research process of foreign thermal batteries,the research progress of thermal batteries in my country is relatively slow,and affected by the current changeable international situation,all countries in the world are constantly strengthening their own national defense forces and constantly updating weapons and equipment,especially It is high-tech weapons and equipment such as nuclear bombs,supersonic missiles and various artillery defense systems.The research and development of these continuously upgraded high-tech weapons is almost inseparable from the thermal battery as a power source or activation power source.Therefore,my country’s thermal battery research must keep up with the upgrading needs of weapon electronic equipment.At present,the thermal batteries that have been commercialized in my country are mainly lithium-based,and the cathode materials are mostly Fe S₂ and vanadium oxide.However,these cathode materials have problems such as easy decomposition at high temperature,matching with electrolyte,and single battery model,which cannot meet the needs of military batteries.Due to the demand for multiple models and high performance,it is necessary to further study and improve new cathode materials on the basis of traditional materials.In view of the current application requirements of thermal batteries for high power and long life,NiCl₂ and NiO are selected as cathode materials,and their discharge performance is studied,and different solutions are proposed according to the respective defects of the two materials.The main work content as follows:Firstly,the flake NiCl₂ powder with loose structure was prepared by a simple segmented high temperature method,and its discharge performance under different discharge regimes was studied.The results show that the suitable working temperature of the NiCl₂/E cathode is 500℃,but it is accompanied by serious leaching and overflow.The negative effect of Mg O on the discharge performance of the battery is clarified.But it will increase the internal resistance and reduce the voltage;NiCl₂/E-TiN is prepared by using TiN instead of Mg O,the results show that TiN can be used stably in the positive electrode,and the discharge curve is stable;TiN has a certain inhibitory effect on the overflow phenomenon of NiCl₂ positive electrode,And due to its conductive effect,it can improve the discharge voltage platform and specific energy;the discharge performance at a circuit density of 0.3 A/cm² exceeds that of the NiCl₂/E-Mg O cathode,which can reach a specific capacity of 410m Ah/g and a specific energy of 874.8 Wh/kg;Combining the respective advantages of Mg O and TiN,NiCl₂/E-Mg O/TiN was prepared and the discharge test was carried out.A specific energy of 341m Ah/g and a specific energy of 790 Wh/kg;when NiCl₂:E-Mg O/TiN=8:2 in NiCl₂/E-Mg O/TiN,the single cell has the best discharge performance;At the same time,the mechanism of Mg O/TiN improving the discharge performance of NiCl₂ cathode was analyzed.Mg O and TiN have a synergistic effect in the cathode,which can reduce the internal resistance of the battery while controlling the overflow infusion.Secondly,for the long-life cathode material,NiO was selected as the cathode material,and its discharge performance under different conditions was studied.The ternary Li Cl-Li Br-Li F electrolyte can better match the NiO cathode,and is suitable for discharge at different temperatures,and the curve is more stable.When discharged at a current density of 0.15 A/cm²,NiO has a specific discharge capacity of 672.9 m Ah/g,while when discharged at a current density of 0.05 A/cm²,NiO has a specific discharge energy of 866.5 Wh/kg;at the same time,NiO also has a certain discharge capacity.The working time of NiO anode can be better extended by increasing the amount of anode,and the proportion of voltage above 1.0 V is more than 90%.When the amount of cathode is 0.4 g,the working time exceeds 3000 s,which shows that NiO is well suited for use as a long-life thermal battery cathode.Adding 15%Ni powder conductive agent can better improve the discharge performance of NiO cathode.The discharge specific capacity of the battery is 690 m Ah/g,the specific energy is 963.1 Wh/kg,and the voltage platform is increased to between 1.4 and 1.5 V.Finally,the Ni/NiO composite cathode material was prepared by a simple thermal decomposition method.The effects of temperature and holding time on the phase composition and microstructure of Ni/NiO were studied,and further discharge tests were carried out.The results showed that:The thermal decomposition of Ni（Ac）₂·4H₂O can prepare Ni/NiO composites without other impurities.The microscopic morphology shows spherical particles of～1μm,accompanied by some nanoparticles dispersed around,and these spherical particles are composed of finer nanoparticles..The preparation temperature with optimal discharge performance is 450°C and the holding time is 4.5 h.At this time,the battery has a maximum voltage of 1.5951 V,a specific capacity of 632.55 m Ah/g,and a specific energy of 919 Wh/kg,which is higher than that of the NiO cathode.This is due to the existence of Ni in Ni/NiO and nanomaterials shortening the ion transport path and reducing the internal resistance of the battery.