Study On Preparation And Properties Of NiCl₂ And Cu₂V_2-xMo_xO₇ Cathode Materials For Thermal Battery

The thermal battery has the characteristics of rapid activation,long storage time,excellent thermal stability and electrochemical performance,and can adapt to the harsh working environment.Therefore,it has the advantages that other batteries can't match in weapon equipment and some special fields.The most widely used is the LiSi/sulfide system.However,with the continuous development of science,thermal batteries are required to develop toward miniaturization,high voltage,and high specific capacity.In this paper,the high potential cathode materials such as copper vanadate?Cu₂V₂O₇?and NiCl₂ were studied.The Cu₂V_2-xMo_xO₇ cathode material with better conductivity was synthesized by sol-gel method.The structure and morphology were characterized by X-ray diffraction?XRD?,scanning electron microscopy?SEM?and differential thermal analysis?DTA?.The discharge performance of the single cell was tested by changing the Mo content,the electrolyte and the addition of the conductive agent in the positive electrode and the like,thereby obtaining the optimum test conditions.The results show that the positive electrode material with 25%electrolyte and 10%conductive agent Ag in the cathode material Cu₂V_1.85Mo_0.15O₇ has the best discharge performance,the initial discharge voltage is 2.964 V,the high voltage discharge platform is stable,and the specific capacity reached 580.2 mAh/g when the cut-off voltage is 1.0 V.The NiCl₂ material was treated by high temperature sublimation process.The characterization results show that the obtained NiCl₂ cathode material has better structure.In view of the poor conductivity of NiCl₂ materials,the addition of metal and non-metal conductive agents was studied,and the modification of mixed conductive agents was explored.It was found that when the compounded nickel powder:graphene was 7:3 mixed conductive agent,the single cell has the best discharge performance,the initial discharge voltage is 2.43 V,and the specific capacity at the cut-off voltage 1.0 V is 279.5 mAh/g.Based on the improvement of NiCl₂ and electrolyte impregnation,and improving the stability of discharge,carbon-coated NiCl₂ cathode material was prepared by carbon coating method.The best effect was achieved by using 10%sucrose,the initial discharge voltage was 2.46 V,and the specific capacity is 308 mAh/g when the cut-off voltage is 1.0 V.The NiCl₂ film electrode was prepared by screen printing.The selection of the binder showed that MgO can meet the requirements of high energy output,but the bonding performance of vapor phase SiO₂ is better.It was subsequently found that the blending binder can combine the advantages of both.The optimum blending ratio is MgO:SiO₂=90%:10%.At this time,the overall performance of the nickel chloride thermal battery is optimal,and as the cut-off voltage is 1.0 V,the specific discharge capacity is 245.7 mAh/g.When 10%activated carbon is added as a conductive agent,the initial discharge voltage is 2.4324 V,and the discharge platform voltage is high and stable.When the voltage is cut off at 1.0 V,the specific capacity reaches 209.3 mAh/g.