(上海海事大学 商船学院，上海 201306)
摘 要: 提出了具有渐变孔隙正极结构的主动式锂空气液流电池，利用溶液泵驱动电解液循环，结合渐变孔隙正极结构，强化电极内部Li+和O2扩散和结合能力，减弱电极钝化。基于COMSOL Multiphysics 5.3，建立二维电化学模型，用Darcy定律、Butler-Volmer方程和组分输运公式描述在渐变孔隙正极结构(ε=0.55+αX等)下电极内部电解液流动、正负极电化学反应及电解液中Li+和O2浓度场分布。由于Li2O2积聚在正极孔隙内，电极比表面积下降，采用Carman-Kozeny方程修正渗透率K。研究渐变孔隙率、压强差、氧气参数、正极厚度及动力学速率系数对该电池放电性能影响。结果表明：在放电电流密度0.1 mA/cm2，电池比电容量是被动式结构的2.5倍；与ε=0.85-0.1X相比，采用ε=0.55+αX结构的电化学性能较佳；在放电电流密度0.1 mA/cm2下，正极厚度为500~750 μm，电池放电性能较好。
关键字: 锂空气液流电池；主动式结构；渐变孔隙率；数值仿真
（School of Merchant Marine, Shanghai Maritime University, Shanghai 201306, China）
Abstract:Lithium-air flow battery with active gradual-change porosity cathode was proposed in which more oxygen in the electrolyte and electrochemical reaction occured due to the utilization of solution pump to drive electrolyte recycled and gradual-change porosity to achieve better O2 migration in cathode. Based on COMSOL Multiphysics 5.3, a two-dimensional electrochemical model was established. The electrolyte flow, electrochemical reactions in the cathode and anode as well as the Li+ and O2 concentrations in the gradual-change porosity cathode of ε=0.55+αX etc, were described by Darcy’s law, Butler-Volmer equation and component transport formulae, respectively. The permeability K inside porous cathode changed with the electrochemical reaction as the occurrence of Li2O2 deposition in the pore, which was modified by Carman-Kozeny equation. The effects of discharge current density, porosity, pressure difference, oxygen parameters, cathode thickness and kinetic rate coefficient were investigated. The results show that the 2.5 times capacitance occurs in the active lithium-air battery at 0.1 mA/cm2 current density than that of a passive mode; more electrochemical reaction happens in the gradual-change porosity cathode of ε=0.55+αX in comparison with that of ε=0.85-0.1X; and better discharge performance can be obtained in the 500 μm to 750 μm thick cathode of active lithium-air battery at 0.1 mA/cm2 current density.
Key words: lithium-air flow battery; active cathode structure; gradual-change porosity; numerical simulation
