tailieunhanh - Semi-suspension technology for preparation of tetrabasic lead sulfate pastes for lead-acid batteries

A new technology for production of 4BS pastes for the positive (lead dioxide) plates of lead-acid batteries has been developed based on an Eirich Evactherm1 mixer. The basic principle of this new technology is that 4BS crystals with dimensions between 20 and 25 mm are formed ®rst from a semi-suspension at a temperature higher than 908C and then the excess water is removed from the semi-suspension under vacuum until the desired paste density is obtained. During the vacuum treatment the temperature of the paste decreases and small 4BS and PbO crystals are formed. . | ELSEVIER Journal of Power Sources 95 2001 191-202 Semi-suspension technology for preparation of tetrabasic lead sulfate pastes for lead-acid batteries D. Pavlov S. Ruevski Central Laboratory of Electrochemical Power Sources Bulgarian Academy of Sciences 1113 Sofia Bulgaria Abstract A new technology for production of 4BS pastes for the positive lead dioxide plates of lead-acid batteries has been developed based on an Eirich Evactherm1 mixer. The basic principle of this new technology is that 4BS crystals with dimensions between 20 and 25 pm are formed first from a semi-suspension at a temperature higher than 90oC and then the excess water is removed from the semi-suspension under vacuum until the desired paste density is obtained. During the vacuum treatment the temperature of the paste decreases and small 4BS and PbO crystals are formed. During the paste formation procedure the large 4BS crystals build up the PbO2 skeleton of the PAM whereas the small crystals form the energetic PbO2 structure which participates in the charge-discharge processes on cycling of the battery. It has been found through XRD and thermogravimetric analysis that the 4BS particles comprise crystal and amorphous zones. The crystal zones contain water molecules part of which can be easily removed from the particles under vacuum treatment and curing as a result of which the crystallinity of the 4BS particles decreases. Another part of the bound water remains in the 4BS particles after curing of the pastes and can leave them only after heating to 250oC. The ability of water to leave the particles depends on the density of the semi-suspension used for preparation of the paste. Experimental tests have shown that the highest battery performance is obtained when the paste is prepared under the following conditions degree of lead oxidation in the leady oxide LO 85 PbO LO H2SO4 LO ratio 5-6 liquid content H2SO4 H2O in the semi-suspension 240-260 ml kg LO temperature of the semi-suspension equal to or