Simulation And Experimental Study On Composite Additives Of Negative Substrate And Electrolyte For Zinc Nickel Single Flow Battery

Zinc electrode has the advantages of low cost,wide source,no environmental pollution,low equilibrium potential and high specific energy,which is widely used in alkaline batteries.However,zinc dendrite growth,passivation and self-discharge were easy to occur in zinc-based secondary batteries during charge discharge cycle,which will seriously affect the performance and cycle life of the battery.At present,the above problems were generally solved by changing the anode substrate and using electrolyte additives.The main research method was experiment,but the experiment process may be limited by environment,technology,experimental conditions and other factors,and cannot verify and explain the experimental results from a micro perspective.In this paper,the influence of four kinds of negative substrate such as nickel plated steel strip on zinc negative electrode of zinc nickel single flow battery was studied by first principle and experiment,and the best negative substrate for the comprehensive performance of zinc nickel single flow battery was selected.Based on the determination of anode substrate,the influence of composite additives?Sn,Ga and Pb?on battery performance was studied by means of cyclic voltammetry curves,constant current charge discharge and SEM image,so as to improve battery performance.The specific research contents and findings were as follows:First of all,considering the industrial production and battery industrial application,copper strip,nickel plated steel strip,stainless steel strip and manganese copper nickel alloy strip were selected as the negative substrate of zinc nickel single flow battery.Taking nickel plated steel strip,stainless steel strip,copper strip and manganese copper nickel alloy strip as models,the Zn adsorption energy,optimal adsorption position,surface energy and electronic work function of the model were calculated.The results showed that the best adsorption positions of nickel plated steel strip,stainless steel strip and copper strip model were vacancy,exothermic reaction and spontaneous,while the best adsorption position of copper strip was above Mn atom and not easy to spontaneous.The easy degree and adsorption rate of Zn adsorbed on the substrate were nickel plated steel strip,stainless steel strip,manganese copper nickel alloy strip and copper strip in turn,and the nickel plated steel strip model were the most stable and the worst activity after Zn adsorption.The electronic work function of copper strip model was the largest,followed by nickel plated steel strip model and stainless steel strip model,and manganese copper nickel alloy strip model was the smallest.Secondly,the effects off the four kinds of negative substrate on the zinc negative electrode of zinc nickel single flow battery were studied by cyclic voltammetry,self-discharge test and SEM images.The results were compared with the calculated results.The results showed that compared with the other three kinds of substrate,the exchange current density I₀ of nickel plated steel strip was the largest,which indicated that the dissolution rate of zinc deposition was the largest,which conformed to the above calculation results of adsorption energy,and the hydrogen evolution reaction and corrosion reaction of nickel plated steel strip were also the weakest.The coulomb efficiency of nickel plated steel strip was the highest under different current densities.The reaction resistance of nickel plated steel strip was smaller than that of the other three kinds of substrate,which was closer to that of zinc itself.The deposition morphology of nickel plated steel strip was the most flat,and the grain gap was the smallest,which was in accordance with the above surface energy calculation results.The self-discharge efficiency of nickel plated steel strip was next to that of copper strip,which was in accordance with the calculation results of electronic work function.Considering the results of calculation and experiment,the nickel plated steel strip was more suitable to be used as the negative substrate of zinc nickel single flow battery.Finally,the effects of composite additives?Sn,Ga and Pb?on the zinc negative electrode of zinc nickel single flow battery were studied by using the negative substrate of nickel plated steel strip.The results showed that the electrode with composite additives had strong cathodic polarization and the lowest potential for electrodeposition,and the hydrogen evolution reaction and self-corrosion reaction were also weak.The composite additive could improve the charging voltage and discharge voltage,and the coulomb efficiency was higher.The composite additives improved the morphology of electrodeposited coatings and produced smaller grains.The effect of Sn and Ga composite additives on self-discharge inhibition was better,and the addition of Pb could improve the self-discharge inhibition to some extent,but it was not obvious.