Tg. Chang et Dm. Jochim, Structural changes of active materials and failure mode of a valve-regulated lead-acid battery in rapid-charge and conventional-charge cycling, J POWER SOU, 91(2), 2000, pp. 177-192
Citations number
34
Categorie Soggetti
Physical Chemistry/Chemical Physics","Environmental Engineering & Energy
Spirally wound 12-V valve-regulated lead-acid batteries were subjected to c
onventional-charge and rapid-charge cycling tests. The cycle life was 250 c
ycles for the conventional-charge regime and 1000 cycles for the rapid-char
ge regime. In conventional-charge cycling, the positive active material qui
ckly expanded and developed a coralloid structure in association with lower
ed utilisation and integrity. In rapid-charge cycling, no coralloid structu
re developed and the expansion was smaller and much slower. Correspondingly
, the particle size of the negative active material grew in both cycling te
sts, but at a much slower rate in rapid-charge cycling. With the expansion
of the positive active material, the negative active material was compresse
d. In the failed batteries, about one-third of the negative active material
in the centre of the electrode was compressed almost into a solid non-poro
us mass. This densification process also occurred at a much slower rate in
rapid-charge cycling. At the point of failure, the discharge capacity of al
l test batteries was limited by the negative electrode, although it was lim
ited by the positive electrode at the beginning of the cycling tests. The c
ause of failure for most of the batteries, regardless of the charging regim
e, was the occurrence of "soak-through" shorts caused by numerous minute le
ad dendrites formed in the separator. This might have been encouraged by th
e formation of shorter distances between the two electrodes, created by the
compression of the separator as a result of the expansion of the positive
active material. (C) 2000 Elsevier Science S.A. All rights reserved.