Influence of lead foam grid on charge acceptance of VRLA battery

Lead foam and cast grid were used as the negative electrode for valve-regulated lead acid (VRLA) batteries. Results of charge-discharge cycle test show that, when pasted the same negative active material (NAM), both the utilization of NAM and the capacity of lead foam VRLA battery are higher than those of cast grid VRLA battery, and lead foam VRLA battery has better charge acceptance. Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and SEM were applied to the two kinds of negative electrodes at the state of discharge, and the real surface areas were tested by chronoamperometry. The results show that compared with the cast grid negative electrode at the state of charge, the oxidization peak of lead foam is a little negative and the reduction peak is positive; the values of the current for the oxidization peak and the reduction peak are larger; electrochemical reaction resistance is smaller; real surface area is larger; size of PbSO₄ crystals formed in the NAM is smaller; and that lead foam to the charge reaction.