tailieunhanh - Selection of pre-blended expanders for optimum leadracid battery performance

Expanders are an essential component of leadracid batteries. They prevent performance losses in negative plates that would otherwise be caused by passivation and structural changes in the active material. The functions of the components of modern negative-plate expanders are described and data are presented to show how the capacity and life of the battery are affected by the type and amount of barium sulfate and lignin incorporated in the expander blend. The differences between expanders for automotive, deep-cycle and standby-power batteries are illustrated and typical formulations shown for each application. There are several ways in which expanders can be. | ELSEVIER Journal of Power Sources 73 1998 89-92 Selection of pre-blended expanders for optimum lead acid battery performance . Boden Hammond Lead Products A Division of Hammond Group 2323 165th Street Hammond IN 46325 USA Received 10 August 1997 accepted 20 December 1997 Abstract Expanders are an essential component of lead acid batteries. They prevent performance losses in negative plates that would otherwise be caused by passivation and structural changes in the active material. The functions of the components of modern negative-plate expanders are described and data are presented to show how the capacity and life of the battery are affected by the type and amount of barium sulfate and lignin incorporated in the expander blend. The differences between expanders for automotive deep-cycle and standby-power batteries are illustrated and typical formulations shown for each application. There are several ways in which expanders can be incorporated into negative plates. These range from adding the individual components to the paste mix to adding a pre-blended formulation. The benefits of pre-blending are more uniform distribution of expander in the plate simplification of paste mixing and improved quality control. 1998 Elsevier Science . All rights reserved. Keywords Lead acid batteries Expanders Lignosulfonates Barium sulfate Negative plate 1. Introduction Without the use of expanders the active material sponge lead in the negative plates of lead acid batteries will lose performance rapidly when cycled. This performance loss is due to passivation which results from deposition of an impermeable film of lead sulfate on the lead substrate and to loss of porosity caused by shrinkage of the lead sponge. Studies have shown 1-3 that there is considerable reduction in the surface area of the negative plate after relatively few cycles. The above behaviour can be reduced significantly by the use of certain additives to the negative plate. These additives are usually .