Numerical Simulation And Analysis For Internal Multi-physical Fields Of Zinc-nickel Single Flow Battery

The need for renewable energy is due to the recognition that the supply of fossil fuels is rapidly drying up for adverse environmental impacts and energy consumption is increasing because of the growth of the global population and the demand for a higher standard of living.The utilization of intermittent renewable energy in the future requires low-cost and reliable energy storage system.It has long been recognized that stationary systems could save substantial quantities of energy,as well as provide other potential benefits,such as improved reliability and reduced emissions.In all kinds of electrochemical energy storage systems,redox flow batteries have the advantages of strong independent energy storage and power generation capacity,flexible positioning,high efficiency,low scale cost,long charging and discharging cycle,etc.,and have broad application prospects.Among them,zinc-nickel single-flow battery has high open-loop voltage and energy density,simple structure and low cost,which has attracted extensive attention in recent years.The main research work of this paper is as follows:(1)Assuming that the electrolyte in the porous electrode is stationary,a threedimensional stationary model was established.The model is based on the universal conservation laws and a kinetic model for reaction involving hydroxide and zinc ions,and is applied to describe a zinc-nickel single flow battery cells stack.The electrolyte within the porous electrode is assumed to be stationary.The model is validated against the experimental data and is used to describe the spatial distribution of flow,concentration,current density and potential.The effects of variations in electrolyte flow rate and concentration are further studied.(2)A two-dimensional transient model for the study of zinc-nickel single flow battery was developed.The model is based on a comprehensive description of mass,momentum and charge transport and conservation,combining with a global kinetic model for reactions involving ions and proton.The model further considers the flow in porous media.The model is validated against the experimental date and is used to study the effects of variations in concentration,flow rate,and applied current density.(3)Based on the comprehensive description of mass,momentum and charge transport and conservation,as well as the dynamic equation involving ion and proton reactions,the previous two-dimensional transient model was extended to three-dimensional.The model is more detailed and considers the structure of the current collectors and the pole lugs.The validity of the model is verified by experiments.On this basis,the influence caused by the presence of electrode lugs,including the change on the distributions of current density and concentration distribution and the loss of voltage.Finally,the model is used to design and optimize the parameters of electrode lugs including structure,location and number.