Impedance spectra of enhanced flooded batteries for micro-hybrid applications

•At lower frequencies, there is a smaller slope in the impedance spectra of the carbon-containing battery.•There is deviation from a semicircle in the diffusion branch of the fully charged battery.•An explanation for the deviation is a hindered diffusion process.•Impedance data hint that carbon acts as catalyst especially for the charge reaction.

The contribution presents impedance spectra of enhanced flooded batteries (EFBs) with reference electrodes for micro-hybrid applications. Batteries of different manufacturers are compared, also with respect to the temperature-dependency of their impedance spectra. Spectra fitting to suitable electrochemical equivalent circuits (EECs) allows a more thorough understanding of the physicochemical processes in these lead-acid batteries.