Because of their commercial acceptability, Lead-Acid batteries are of significant importance, thus researchers constantly attempt to find new approaches to enhance their efficiency. In the present study, I sought to modify surface of the negative grids with aniline in sulfuric acid solution. Then, the modified grids were used as current collectors in negative plates of the cells in Lead-Acid batteries. The XRD, SEM, XPS, chronopotentiometry and cyclic voltammetry were employed for characterization of the modified grids, and constant current charge/discharge and electrochemical impedance spectroscopy techniques were used for studying the performance of the Lead-Acid cells. The results indicate that the growth of polyaniline fractal modifies the distance between the collector grids and active materials and the process of PbSO4 reduction to the metallic lead is enhanced on the modified lead grid. Although modification of the collector grids in negative plate seems to have no significant effect on the initial capacity of the cells, the grids modified with a 5mM aniline solution shows a higher cumulative capacity after 90 complete charge/discharge cycles. XRD analysis on the negative active materials revealed a decrease in accumulation of the lead sulfate crystals on the negative plate. So, taking the decay in capacity to 35% of the initial amount as a criterion, cycle life of cells increased from 35 in the cells with commercial plates to >100 in the cells of the modified grids. Such a modification with three folds increment in battery life would help the Lead-Acid batteries to compete in the modern world.