Simulation Study On The Discharge Performance Of Aluminum-Water Battery Based On COMSOL

Aluminum-water batteries have the advantages of high specific energy,good safety and simple operation,and their application to UUVs can significantly enable the UUVs to have a longer operating capability.However,the aluminum-water battery does not have high output capacity,which will reduce the maneuverability of the UUV.The battery design parameters such as electrolyte conductivity and pole plate spacing of aluminum-water battery,as well as the anode corrosion and the concentration polarization caused by ion movement during the operation of aluminum-water battery will affect the battery capacity to provide power.Therefore,it is necessary to simulate and analyze the working process of aluminum-water battery,to study the influence of various factors on the battery performance during the working process of aluminum-water battery,and to provide theoretical basis and technical support for optimizing the battery structure and improving the output power of the battery.This paper adopts the secondary current distribution interface in COMSOL software and establishes the numerical model of single-stage aluminum-water battery.The effects of electrolyte conductivity,pole plate spacing and other design parameters on the battery performance are studied to provide theoretical basis for optimizing the structure of aluminum-water single cell and improving the battery discharge performance.The anode corrosion process of the aluminum-water battery is simulated and analyzed through the secondary current distribution interface combined with the level set function to study the influence of the corrosion process of the anode on the battery discharge performance.The motion of aluminum ions in the electrolyte was simulated using a secondary current distribution interface coupled with a diluted species transport interface.The influence of each factor on the concentration polarization was analyzed to improve the battery discharge performance by reducing the concentration polarization.The discharge performance of the battery pack with different displacements is studied.The discharge capacity of the battery is improved by constructing an aluminum-water battery pack.The main research results of this paper are as follows :(1)The following results are obtained from the numerical model simulation of singlestage aluminum-water battery: The maximum output power density of the battery is significantly increased by increasing the electrolyte conductivity,reducing the pole spacing and decreasing the passivation film thickness.When the conductivity is increased from 1S/m to 6S/m,the maximum output power density is increased by 2 times.The maximum output power density is increased by 66% when the pole plate spacing is reduced from 2cm to0.25 cm.When the passivation film resistance is reduced to 75% of the original value,the maximum output power density is increased by 30%.(2)The following results are obtained through the simulation calculation of the anode corrosion process of single-stage aluminum water battery: As the reaction proceeds,the anode reaction area decreases and the local current on the anode surface increases continuously,which intensifies the corrosion of the aluminum anode.In the process of anode corrosion,the cell voltage decreases continuously.(3)The following results are obtained by simulating the movement of aluminum ions in the electrolyte of single-stage aluminum water battery: As the electrode reaction proceeds,aluminum ions form a large concentration gradient near the electrode,resulting in concentration polarization,which causes the degradation of battery performance.Increasing the discharge current and decreasing the ion diffusion coefficient can prolong the discharge time.However,both will aggravate the concentration polarization and cause the loss of battery discharge performance.The electrolyte flow can significantly reduce the differential polarization and improve the discharge capacity of the battery.(4)A comparative analysis was conducted on the discharge performance of battery packs with different arrangement methods.The output power of series battery packs,parallel battery packs,and staggered electrode arrangement battery packs is significantly improved compared to individual batteries.The series battery pack has the highest output voltage and is suitable for applications where electrical appliances have a high demand for voltage.The staggered arrangement of electrode plates in the battery pack can achieve the highest output power while minimizing its volume,making it suitable for situations where voltage demand is not high,space is limited,and larger power is required.