双电解质锂-空气电池放电特性分析

Analysis of discharge characteristics of dual electrolyte lithium-air battery

空气电池的氧气传递与空气电极厚度和电流密度有密切联系。基于电极反应动力学和传质原理,利用COMSOL Multiphys软件,建立双电解质锂-空气电池二维瞬态等温模型,分析空气电极厚度和电流密度对放电过程中氧浓度、LiOH·H_(2)O体积、孔隙率分布和电池性能的影响。空气电极太薄,无法提供充足的氧气以及电化学反应活性位点;空气电极太厚,会增加反应物传递阻力,导致电池性能下降。较大的电流密度会增加欧姆阻抗和电池极化,导致电池性能降低,因此,较小的电流密度更有利于提升电池的放电性能。

The oxygen transfer in air battery was closely related with the thickness of air electrode and current density.Based on the principles of electrode reaction kinetics and mass transfer,a two-dimensional transient isothermal model of dual electrolyte lithium-air battery was established by using COMSOL Multiphys software.The effects of thickness of air electrode and current density on oxygen concentration in discharge process,LiOH·H_(2)O volume,porosity distribution and battery performance were analyzed.Sufficient oxygen and active sites of electrochemical reaction couldn’t be provided by too thin air electrode,while the reactant transfer resistance was increased and the battery performance was decreased by the influence of thick air battery.Ohmic impedance and battery polarization were increased and the battery performance was decreased by higher current density.Therefore,lower current density was more beneficial to improve the discharge performance of battery.