| Aviation lithium battery,as the emergency power supply and ground auxiliary power supply of civil aircraft,has been widely used in aircraft,and once it is on fire,the consequences will be very serious.In order to improve the performance of aircraft,it is necessary to develop a safe lithium battery system with higher energy density.The metallic lithium anode has an ultra-high theoretical specific capacity and has become one of the best materials for the next generation of rechargeable lithium battery anodes with high specific energy.However,the spontaneous solid electrolyte interface（SEI）with uneven surface and poor mechanical properties of lithium anode causes the instability of electrodeposition interface,leading to battery failure and even explosion accidents.Therefore,in this paper,the cost-effective strategy of building in-situ artificial SEI film is adopted to modify the SEI film of metallic lithium anode.The substitution reaction between THF solution of Al Cl3 and metallic lithium is designed to form Al/Li Cl composite SEI film on the surface.The metallic lithium anode was assembled into a Li-Li symmetrical battery for testing,the concentration of 0.05 M Al Cl3 solution and the reaction time of 15s were determined as the best preparation process.Under the current density of 1m A/cm2and consant current charge discharge of 1m Ah/cm2,the battery stably cycles for 300 cycles,and the overpotential is always less than 0.1V.The electrochemical impedance spectroscopy test was tested.When Al/Li Cl-Li anode is cycled from 10 to 50 cycles,the impedance growth of SEI film is much smaller than that of bare lithium anode,which improves the stability of the battery interface.The cathode LiFePO4 was assembled into a full battery,the results show the significance of Al/Li Cl SEI film in practical production.It stably cycles for 200 cycles at 1 C and the capacity retention rate is about 91.4%.No dendrites are produced after 100 cycles.Under the 0.2 C-5 C rate,the capacity is increased by about 20 m Ah/g.The rate performance is improved.Comprehensive analysis of the relationship between the structure morphology and electrochemical performance of the in-situ composite SEI film shows that the Al/Li Cl component improves the diffusion ability of lithium ions in the SEI film,and enhances the chemical and structural stability of lithium anode.The experimental results were used to obtain parameters such as the diffusion coefficient of lithium ions in the Al/Li Cl composite SEI film,and the battery discharge model was simulated.The lithium-sulfur battery with Al/Li Cl-Li anode has a small decrease in capacity and voltage at 5 C,and the concentration of the lithium ion is evenly distributed at 0.2 C,which improves rate performance.The discharge behavior under the influence of temperature was studied.The voltage decreases with the decrease of temperature,and the low temperature reduces the discharge capacity of the battery,indicating that the rapid diffusion of the SEI film can not improve the degree of temperature influence on the battery. |
