Study On Modification For Lithium Fluoride Carbon Primary Battery

Lithium fluoride carbon battery is the primary battery with the highest theoretical mass energy density,up to 2160 Wh/Kg.Lithium fluoride carbon primary battery has the characteristics of stable voltage platform,can be adapted to discharge at various temperatures,small self-discharge rate,long service life and so on.However,due to the strong covalentity of the fluorocarbon bond in the fluorinated carbon materials,the fluorinated carbon materials has poor conductivity.At the same time,the surface energy of the fluorinated carbon is low,and the permeability of the electrolyte is poor.When the positive electrode materials is used,the battery polarization is serious,the rate performance is poor,and voltage delay is prone to occur.It is difficult to meet the requirements of special occasions such as high rate and large current discharge.In order to improve the rate performance of the battery and reduce the voltage delay,the thesis aims at optimizing the composition of the positive electrode sheet and surface coating of the fluorinated carbon materials for the above problems.For the optimization of the composition of the positive pole piece,three different conductive additives Super P,Ketjen Black,and carbon nanotubes(CNTs)were mixed with fluorocarbon to make the positive pole piece of the battery.By optimizing the best positive electrode active materials,conductive agent,and adhesion according to the mixing ratio of the binding agent,the best positive electrode sheet composition:mass ratio of active materials,conductive agent and binder is 85:5:10.On this basis,the mixture of carbon and manganese dioxide is coated on the surface of the carbon fluoride,and the manganese dioxide acts as an active materials,effectively alleviating the voltage delay problem of the lithium carbon fluoride cathode materials;but due to the high temperature decomposition of glucose,The carbon has poor conductivity,which makes it difficult to play the capacity of the battery.In the following research,high-conductivity carbon nanotubes(CNTs)and fluorinated carbon/manganese dioxide materialss were selected to effectively reduce the polarization.At a 2 C rate the specific capacity is 558 mAh/g,accounting for64.9% of the theoretical specific capacity,which is 6.3% higher than the original CFx materials.Finally,this paper also designs a three-dimensional current collector modified lithium anode Structure.Nickel foam is used as the three-dimensional framework,and the zinc oxide nanoarray layer is grown in situ on the surface to provide lithium-philic adsorption sites.Zn-MOF has high ion conductivity,and further improves the lithium-philic adsorption sites and increases the three-dimensional current collector capacity for lithium.The three-dimensional lithium anode structure can effectively avoid the formation of lithium dendrites and improve the life of lithium batteries.The lithium nucleation potential of the prepared ZnO-MOF@Ni composite structure can be as low as 5.6 mV,only one-seventh of the bare nickel foam as the anode carrierAfter 40 cycles,the battery's coulombic efficiency is still close to 97%,while nickel foam as the skeleton shows a significant short circuit phenomenon,and the coulombic efficiency is reduced to zero.