ORIGINAL PAPER B. Rezaei Æ S. Damiri Effect of solidification temperature of lead alloy grids on the electrochemical behavior of lead-acid battery Received: 12 October 2004 / Revised: 28 October 2004 / Accepted: 12 November 2004 / Published online: 22 January 2005 Ó Springer-Verlag 2005 Abstract One of the main electrochemical characteristics of a lead-acid battery is amount of water consumption. The effect of solidification temperature on electrochem- ical behavior (mainly hydrogen overvoltage) of Pb–Ca– Sn–Al (0.09%, Ca; 0.9%, Sn; 0.02%, Al) and Pb–Sb–Sn (1.7%, Sb; 0.24%, Sn) alloys, which are used in making the grid of lead-acid batteries, has been studied by cyclic voltammetry (CV) and linear sweep voltammety for different concentrations of sulfuric acid (ranging from 0.5 mol L À1 to 4.0 mol L À1 ). The morphology of the grid at some solidification temperatures was studied by optical microscopy. After one sweep of CV the surface of the electrode was investigated by using scanning electron microscopy.The results show that the potential of hydrogen evolution depends on the solidification temperature of the grids during production (mold tem- perature of grid casting). Also, at different solidification temperatures, different passivation phenomena, elec- trode surface constituents, and structure were observed. Keywords Lead alloy Æ Mold temperature Æ Hydrogen overvoltage Æ Lead-acid battery Introduction Lead–antimony and lead–calcium alloys are most widely used for production of lead- acid battery grids. These alloys are extremely strong and creep-resistant and can be cast into rigid, dimensionally stable grids that are capable of resisting the stresses of charge/discharge reactions. As the antimony content of battery grids has been reduced, the mechanical properties of the alloys have decreased significantly [1]. The SLI battery grids employed have about 1–3% antimony; antimony en- hances electrolysis of water into hydrogen and oxygen during charging, leading to water loss. Therefore, in order to decrease the amount of water lost and for the production of hybrid and maintenance-free (MF) bat- teries, low-antimony–lead alloys (1.6–1.7 wt.% Sb) were used for grid production and many researchers have paid attention to the electrode characteristics of these alloys [2–4]. It has been shown in the literature that antimony in a lead–antimony electrode affects the microstructure and electrochemical behavior of active materials and corrosion layers on the electrode [5–11]. The use of low-antimony or antimony-free alloys is an effective way to minimize gassing and to achieve maintenance-free lead-acid batteries. Thus, new materi- als have been employed in grid manufacture, e.g., lead– calcium alloy. As little as 0.1% Ca in the lead alloy is sufficient to reduce gassing to a level where the battery can virtually be sealed and no water addition is required [12–13]. These alloys are significantly weaker than lead– antimony alloys. Lead–calcium alloys suffer higher rates of corrosion as the calcium content is increased, but higher calcium contents up to about 0.08 wt.% increase the mechanical properties of the alloys [1]. Tin additives to lead–calcium alloys improve its mechanical properties by changing the mode of precipitation from Pb 3 Ca to the more stable Pb(Sn,Ca) 3 [14]. The use of lead–calcium alloys have lead to ‘‘passivation’’ phenomena at the positive plates; these are attributed to the formation of a poorly conducting oxide layer that has been identified as tetragonal lead oxide, referred as a-PbO. Alloying with tin (the original objective of which was to improve flu- idity during casting) was found to be effective in decreasing grid passivation. Tin decreases the thickness of the PbO layer and increases the electronic conduc- tivity of the passivation layer. The result showed that the conductivity increases sharply for alloying with a tin content higher than 1.5 wt.%. Also, alloying with tin increases the overvoltage of the oxygen and hydrogen evolution reaction [12]. B. Rezaei (&) Æ S. Damiri College of Chemistry, Isfahan University of Technology, Isfahan, Iran E-mail: rezaei@cc.iut.ac.ir Tel.: +98-311-3912351 Fax: +98-311-3912350 J Solid State Electrochem (2005) 9: 590–594 DOI 10.1007/s10008-004-0628-4