Deposition Behavior of Lead in Lead Methanesulfonate Flow Batteries with the Addition of Tin(II) Methanesulfonate

The formation of lead dendrites easily causes short circuiting during charging in lead methanesulfonate flow batteries. In this work, tin(II) methanesulfonate is used as an additive to improve the surface morphology of the lead layer. It has been found that the lead layer is smooth and compact in an electrolyte of 1.5 M Pb(CH3SO3)2 + 1.0 M CH3SO3H with 8 m mol l−1 of additive. During charging, lead and tin can be co-deposited to increase the density of the nucleus number and decrease the diffusion rate of Pb2+. The type of nucleation of lead is changed from three-dimensional instantaneous nucleation to three-dimensional progressive nucleation in the process controlled by the diffusion of Pb2+. This is beneficial for the formation of small-sized lead particles, leveling the morphology of the lead layer, and inhibiting the formation of lead dendrite. The energy efficiency of the flow cell is around 80%, and 380 cycles are achieved in the electrolyte of 1.5 M Pb(CH3SO3)2 + 1.0 M CH3SO3H with 8 mmol l−1 of tin(II) methanesulfonate.