Abstract: The discharging performance of positive active mass containing different additives in lead-acid batteries was studied. On the condition that the capacity of lead-acid battery was limited by a single positive plate, the discharging capacity and energy of lead-acid batteries added with different kinds of additives, such as Bi₂O₃, CdSO₄, CaSO₄ and PbO₂, was tested at different rates of discharge. On the basis of experimental results, higher specific capacity and energy were observed than was recently reported. Some parameters of average diameter, surface area, numbers and distribution of micro-pores were tested by microscopic imaging analysis apparatus and some scanning pictures were taken. Relevant laws of influence and mechanism of the additives were discussed.