Numerical Modeling And Parameter Sensitivity Analyses On The Performance Of An Aluminum-air Battery With Dual Electrolyte Structure

As the main driving energy source for new energy vehicles,power batteries are cleaner and have a higher energy transfer rate than traditional petroleum fuels.Among them,aluminum-air batteries(hereinafter referred to as aluminum-air batteries)stand out from many power batteries because of their high specific energy,high specific power,abundant aluminum resources,safe use and environmentally friendly reaction products.In this paper,a new type of aluminum-air battery with a double electrolyte structure is proposed for the problem that aluminum-air batteries are prone to self-corrosion in alkaline electrolyte.As a research object,the fitting equation of the passive film resistance of the aluminum anode surface is fitted by experiments,Add ion exchange membrane model,and use the modified electrochemical kinetics equation to establish a two-dimensional numerical model of a double electrolyte aluminum-air battery.The experimental results of the simulation results are compared with each other to verify the validity of the numerical model.And use Matlab software to study the sensitivity analysis of battery performance by adjusting various model parameters.The main research contents and results of this article are as follows:1.Double electrolyte battery design,the anode electrolyte uses a neutral electrolyte with low aluminum corrosion rate,and the cation exchange membrane is used to separate the aluminum anode from the OH~-in the catholyte to inhibit the hydrogen evolution reaction;the alkaline with high oxygen reduction activity The aqueous electrolyte acts as a cathode electrolyte to increase the air electrode reactivity.2.A three-electrode device was used to measure the corrosion behavior of different Cl~-concentrations on the passivation film of the aluminum plate,and the surface of the polarized aluminum plate was observed using a scanning electron microscope.According to the experimental test results,the fitting formula of the resistance value of the passivation film on the aluminum anode surface with the discharge current density under different Cl~-ion concentrations is proposed.3.A two-dimensional numerical model that can simulate an aluminum-air battery with a dual electrolyte structure was created,and compared with the experimental results,the validity of the model was verified.The internal characteristic simulation results show that:(1)When an external current passes through the electrode,the electrode will be out of equilibrium,and the potential transition phenomenon will occur at the junction between the positive and negative electrodes and the electrolyte;(2)Due to the selective permeability of the ion exchange membrane,OH~-and Cl~-in the solution are repelled,and a potential transition occurs at the boundary of the ion exchange membrane,causing the Donnan potential to shift.4.A single factor is used to analyze the influence of battery internal design parameters on battery performance.The changes of battery polarization curve and power density curve at 0.25,0.5 and 0.75 times the resistance of the passive film are studied.The results show that:(1)The resistance value of the passivation film on the aluminum electrode is the main obstacle to improve the performance of the battery.When the passive film resistance is reduced to 25%of the existing experimental film resistance,the open circuit voltage can be moved to 1.5 V,and the open circuit potential of the battery is close to that of an aluminum-air battery using an alkaline solution;(2)The thickness of the electrolyte is a secondary factor.When the electrolyte layer is reduced from 10 mm to 2.5 mm,the peak power density of the battery will increase by 210%.5.Using Latin hypercube sampling and SRC global sensitivity analysis,the sensitivity of the selected five battery design parameters was analyzed.The results show that:(1)The film resistance of aluminum-air batteries under normal conditions has a large part of the influence on potential and power;(2)For the discharge current and power of the battery at 1 V,the NaOH concentration also shows good sensitivity.