Journal of Applied Electrochemistry, Vol.46, No.8, 861-868, 2016
A study on Pb2+/Pb electrodes for soluble lead redox flow cells prepared with methanesulfonic acid and recycled lead
Electrodeposition and electrodissolution reactions of the Pb2+/Pb electrode were studied on a glassy carbon rotating disk electrode in aqueous solutions of CH3SO3H and Pb(CH3SO3)(2). The electrolytic parameters, kinematic viscosity and ionic conductivity, were determined with various concentrations of CH3SO3H and Pb(CH3SO3)(2). The diffusion coefficient of Pb2+ in this electrolyte prepared with CH3SO3H was determined by the Levich Equation. Both the concentrations of CH3SO3H and Pb(CH3SO3)(2) were found responsible for the equilibrium potential shifts and exchange current density variations. The electrochemical processes at the Pb2+/Pb electrode were identified as being under mixed ohmic-diffusion control. The electrolyte conductivity and the ionic activity of Pb2+ were recognized as important parameters for designing the soluble lead redox flow cells. During constant current charge-discharge measurement, the specific capacity of the Pb2+/Pb electrode was about 253 mAh g(-1)Pb, about 98 % of the theoretical value. The impurity elements Fe, Ba, Al, and Zn in the Pb2+ electrolytes prepared with recycled lead exhibited insignificant influences on the Pb2+/Pb reactions. It is reasonable to believe that the recycled lead can be applied in soluble lead redox flow batteries, and the cost may be further reduced with recycled lead because expensive impurity-control processes seemed to be avoidable.
Keywords:Soluble lead redox flow cells;Redox flow battery;Methanesulfonic acid;Lead electrodeposition;Lead acid battery;Recycled lead