Study Of Lead And Tin-lead Electroplating On Titanium For Bipolar Lead Acid Battery

Lead-acid batterises have a significant share of the secondary battery market allthe time because of their traditional advantages such as mature production technology,low price and excellent security, etc. However, there are also many disadvantages oflead-acid batterises such as the lower capacity. But bipolar lead-acid batteries have aseries of advantages such as low interal resistance, uniform current density, highspecific capacity, excellent power density and campact battery structure which wellmeet the requirements of the eletric vehicle and eletric bicycles. The key component ofthe bipolar lead-acid batteries is the bipolar substrate. In this paper, lead and tin-leadalloy are electrodeposited on the titanium substrate, then deposit adhesion wasincreased considerably, finally obtained the conductive satisfactory substrate.In this paper, firstly the pre-treatment method of titanum was studied. Afterresearch, the technological process which the grinding, degreasing, washing, etching,water washing, roughening, cleaning, activation treatment process were included wasdetermined. The main focus was on the etching program which aimed at obtaining thefresh titanium substrate; on the roughening program which was with the purpose ofstenghthening the mechanical adhesion; on the activation programs to get a layer ofhydrogenated membrane which could improve the suface adhesion significantly.Besides, optimizing the coarsening and activation programs which increased theefficiency can obtain the titanium surface with a excellent coating adhesion.By studying the lead plating system with the different complexing agents andadditives, the pyrophosphate lead plating system with the additives of TP-2wasdetermined. The coating was smooth and bright and the adhesion of the coating isexcellent. The composition of the bath was simple to prepared and maintained easily.After further research, the optimized process was obtained which was lead acetate:60-64g/L, potassium pyrophosphate:200-240g/L, TP-2:2.5-5g/L, cathode current densityrange:0.5-1.5A/dm2, temperature range:35-45℃, magnetic stirring or stirring byagitator blade.On the basis of lead plating system, stannous mono-sulphate was added into thelead plating system as the tin salt. As a result, the coating appearance was similar to thepure lead plating. The optimization process was: lead acetate:62g/L, potassiumpyrophosphate:220g/L, stannous sulfate:1.67g/L, TP-2:2.5g/L, cathode currentdensity:1A/dm2, temperature:35℃, magnetic stirring or stirring by agitator blade.And the tin content of alloy coating obtained was1.3%. Bipolar lead acid batteries were assembled by the titanium substrate plated by thelead and tin-lead. Through the charge and discharge tests, the discharge capacityretention of the batteries which included the titanium plated lead was only22.5%after60cycles. By contrast, the others is80.6%which is far higher than the previous former.