Two-dimensional transient discharge model of zinc-nickel single flow battery

  Objectives  In order to investigate the internal mechanism of the zinc-nickel single flow battery during its operation,

  Methods  a two-dimensional transient model for a second generation zinc-nickel single flow battery was established taking into account of the momentum and mass transfer, charge conservation and reaction dynamics equations. The finite element method was used for coupling calculation and the distribution of the flow and concentration inside the battery were analyzed. The calculation results were verified through experiment. On this basis, the effects of the electrolyte flow rate and ion concentration were studied.

  Results  The results show that the electrochemical reaction is more intense at larger flow rate. For every 0.5 times increase(or decrease) of flow rate, the hydroxide ion concentration interval decreases(or increases) by 36%-41%, and the zinc ion concentration interval increases(or decreases)by 6.5%-6.6%. The ion concentration distribution tends to be uniform at a larger flow rate, while changing the initial ion concentration has no effect on the uniformity of concentration distribution. The discharge voltage increases by 27 mV on average when the initial hydroxide ion concentration increases by 22%, while the larger initial zinc ion concentration is not conducive to improving the discharge performance of the battery.

  Conclusions  The model can accurately calculate the discharge performance of the battery and is suitable for the mechanism study of zinc-nickel single flow battery.