Optimization Of Electrolyte System And Analysis Of Mesoscopic Mass Transfer In Lithium Air Battery

Lithium air battery is a clean,environmental-friendly metal-air battery,which has attracted much attention because of its ultra-high energy density.It has high prospects for future applications in electric vehicles and energy storage.However,the development and application of lithium air battery has been severely limited due to the problems of poor electrolyte stability,high overpotential,and low number of cycles.On the basis of reading a lot of related literatures of lithium air battery,the classification,working principle,and battery structure of lithium air battery were summarized in this paper.At the same time,the development history of lithium air battery and the problems in their development were introduced.The test platform for lithium-air battery was improved and the performance was conducted.The experiments focused on the effects of electrolyte concentration and lithium iodide content on battery.The behavior characteristics of lithium ion diffusion across the membrane was analyzed.The simulation focused on diffusion and order of positive mass transfer in mesoscopic conditions of lithium air battery.The research includes two parts.The first part is about experiment.?1?To investigate the performance changes of lithium air battery under different concentrations of electrolyte?TEGDME-Li TFSI?.The study found that the peak current,the ohmic impedance,the electrochemical reaction impedance,the degree of oxygen diffusion and the first discharge specific capacity of the lithium air battery increase with the increase of electrolyte concentration.?2?When TEGDME-Li TFS with the same concentration and different volume ratio was added to the 1mol/L TEGDME-Li TFS,the change of battery performance was studied.The study found that with the increase of the amount of lithium iodide in the electrolyte,the peak current of the voltammetric curve gradually increases.The increase of lithium iodide improved the potential difference and the reversibility of the lithium-air battery,which have a positive effect on stabling discharge process and improving the discharge efficiency of lithium air battery.?3?Carbon nanotubes were used as the electrodes of lithium air battery to analyze the diffusion of lithium ions in the electrodes.By changing the temperature of the experimental device,lithium ion concentration,the law of change of diffusion coefficient were explored.The study found that,the diffusion coefficient of lithium ions increased with temperature and decreased with concentration,which are consistent with the simulation part.The second part is about simulation.A mesoscopic mass transfer model of lithium air battery was established.Based on the principle of Martini force field,the Mesocite module in Material Studio was used to build a mesoscopic model.The coarse-grained molecular dynamics simulation method was used to study the change trend and diameter of the diffusion coefficients of H₂O,Li⁺,OH^-and O₂beads in solution distribution function.The effects of temperature,carbon nanotube length,carbon nanotube content and electrolyte concentration for lithium air battery were discussed.The type of carbon nanotubes and the quality of different mixed carbon nanotubes on the diffusion coefficient and ordering of particles were also analyzed in the positive electrode of lithium air battery.The study found that increasing the porosity of the system,reducing the concentration of the electrolyte,and adjusting the complexity of the system are conducive to the improvement of the diffusion coefficient of each particle in the solution system.