Both the electrochemical activity and the energy density of polyaniline (PANI) microparticles suspensions are enhanced by using the compact PANI powder, which is synthesized galvanostatically with 4,4′-diaminobiphenyl as additive. A Zn//PANI suspension rechargeable flow battery system is proposed, in which the flowable PANI suspension is used as cathode electroactive material, zinc plate as anode. A microporous membrane is used as separator to prevent PANI particles from getting into the anode compartment. Results obtained from the small laboratory battery show that the discharge capacity density gradually decreases with number of cycles and the average of discharge capacity loss during 32 cycles is about 0.07% per cycle. However, an average coulombic efficiency of 97% has been achieved at the current density of 20 mA cm−2 and the value of coulombic efficiency shows no significant change during 32 charge/discharge cycles. The flow-through mode for PANI cathode material enables the PANI-based battery to operate at a higher current density in comparison with the conventional Zn–PANI film batteries, and the present findings can mark a new route to improve the performance of conductive polymer-based energy storage devices.