Polarization analysis and optimization of negative electrode nickel foam structure of zinc-nickel single-flow battery

Abstract

The polarization of zinc‑nickel single-flow battery (ZNB) seriously affects the power density of the battery. In this paper, the polarization of ZNB is studied by establishing a three-dimensional polarization model and using the numerical simulation method. Nickel foam (NF) is used to replace conventional nickel-plated steel strip (NS) as the anode, and the polarization of the battery with nickel foam as the negative electrode is studied by the response surface method for the first time. The reliability of the numerical model is proved by experimental comparison, and the effectiveness of the response surface method is also proved by analysis of variance. In this paper, the influence of multiple parameters (thickness of nickel foam, porosity, and flow rate of inlet electrolyte) on the negative polarization degree of the battery is discussed. The coupling function of the negative polarization to each parameter is fitted, and the optimal structure is given. The results show that the optimal nickel foam structure is compared with the traditional nickel-plated steel strip structure, negative activation polarization overpotential and concentration polarization overpotential decrease by 90.28 % and 88.12 % respectively when a state of charge is 0.5. In addition, the negative polarization of the optimal nickel foam structure is discussed with time and space.