Study On Preparation And Electrochemical Of Lithium Carbon Composite Anode

At present,the energy density of lithium ion battery is close to the theoretical limit,which limits its application in power battery with long range and electronic products with long standby time.Lithium metal has much higher theoretical capacity than graphite anode and very low chemical reaction potential,which has been widely concerned by researchers and industry.However,some problems,such as short circuit caused by lithium dendrite formation,serious volume change in circulation process,and side reaction between electrolyte and lithium,still hinder the practical application of lithium anode.Therefore,this paper designed two kinds of lithium carbon composite anode materials,and studied the influence of carbon material structure and carbon content on the structure and electrochemical performance of lithium carbon anode.1.The mixture of AB and CNT（ABC）was obtained by mixing acetylene black（AB）and carbon nanotubes（CNT）.Li ABC anode was prepared by fusion of lithium metal and ABC by hot melting method.Due to the low density of ABC,the lithium philicity of AB,the good conductivity of CNT and the availability of porous skeleton,the symmetrical battery assembled with Li ABC negative electrode shows excellent performance at 1m A/cm² and 0.5 m Ah/cm² surface capacity:After 500 cycles,the overpotential of Li ABC-0.1（carbon content 0.1 wt.%）symmetric battery is 0.03 V,the interfacial resistance is 8.4Ω,the transfer resistance is 56Ω,and only a few cracks and lithium dendrites are generated on the surface.Li ABC-0.1 electrode and lithium iron phosphate electrode（LFP）are assembled into a full battery.After 100 cycles at 0.5 C,the specific discharge capacity of Li ABC-0.1/LFP is 143.9 m Ah/g and coulomb efficiency is 99.6%.At different current densities of different rates,The discharge specific capacity of Li ABC-0.1/LFP full battery is higher than that of Li/LFP full battery.2.Li CZC anode is prepared by fusion of lithium metal with acidified Co₃Zn C（referred to as CZC）by hot melt method.Co₃Zn C is a high temperature carbonized Metal-organic frameworks material（MOFs）.MOFs has the advantages of large specific surface area and porous three-dimensional skeleton structure,which can inhibit the volume expansion of lithium anode and provide sites for lithium deposition.the symmetrical battery assembled with Li CZC anode has excellent performance at 0.5 m Ah/cm² and 1 m A/cm²:After 1000cycles,the Li CZC-10（carbon content 10 wt.%）symmetric battery has 0.008 V overpotential,the interfacial resistance is 2.4Ω,the transfer resistance is 2.3Ω,and only a few cracks and lithium dendrites on the surface.The intensity of the corresponding characteristic peak on the（200）crystal plane is obviously superior.At 0.5 C,Li CZC-10/LFP discharge capacity is145.2 m Ah/g,Coulomb efficiency is 98.2%after 100 cycles,and its reversibility is higher than pure lithium.The discharge specific capacity of Li ABC-0.1/LFP battery is higher than that of Li/LFP battery at different current densities.