Physical Changes in Positive Active Mass during Deep Discharge‐Charge Cycles of Lead‐Acid Cell

Cycle life of the lead-acid battery can be improved by exerting a mechanical pressure on the active material. It reaches up to 3000 cycles in determined conditions which are described. The longest cycle lives are obtained with an exerted pressure in the range 5.104 to 10-10 ~ Pa. These results led to a study of the evolution of stresses occurring in the battery during cycling. Dynamometric rings are put in place of the apparatus exerting the external pressure. Recordings for charges and discharges suggest that internal stress evolutions originate from two causes: thermal expansion and volume change associated with the formation of sulfate. Influence of parameters such as the temperature, the number of plates, the stiffness of the experimental apparatus are studied.

Section: First Series Of Experiments: Evidence Of a Thermalcontrasting

confidence: 71%

Internal Stress Variations in Lead‐Acid Batteries during Cycling

Alzieu

Koechlin

Robert

1987

“…However, despite this large body of work, the possible influence of hydrogen on the electrochemical activity of PbO2 is still open to question since many of the studies have provided ambiguous or conflicting data. Furthermore, recent studies (15,(26)(27)(28)(29) have corroborated earlier, largely ignored, work (30) that suggested that chemical PbO~ may not be electrochemically inactive after all.…”

mentioning

confidence: 57%

The Electrochemical Activity of PbO2 : A Nuclear Magnetic Resonance Study of Hydrogen in Battery and Chemically Prepared Material

Hill

Jessel

1987

Solid-state magic-angle-spinning nuclear magnetic resonance studies have been undertaken on positive plate material from lead-acid batteries and on samples of both pure ~-PbO2 and pure ~-PbO~ prepared by nonelectrochemical methods. Battery positive plate samples contain protons in two different surface and near surface configurations. One of these proton species is associated with mobile, isolated, adsorbed hydroxyl groups, and/or water molecules that can be removed by outgassing. The other proton species is not removed by outgassing; it probably corresponds to water molecules and/or closely spaced hydroxyl groups trapped on internal crystal surfaces. The proton species present in fresh (uncycled) positive plate material are not significantly different in either configuration or abundance from those in extensively cycled samples. Thus, it is unlikely that decline in battery capacity with cycling service is associated with a change in the hydrogen content of PbO2. Chemically prepared varieties of ~-PbO2 and ~-PbO2 are each different from their electrolytically formed counterparts in terms of both the abundance and the nature of the proton species on or near their surfaces; these differences can be related to differences in the manner of their preparation. With the possible exception of chemical ~-PbO2, none of the samples of PbO2 contain protons in configurations attributable to strongly bound, structural hydroxyl groups, as occur in the stoichiometric phase Pb302(OH)2.The role of hydrogen.--The lead-acid battery derives ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 129.173.72.87

“…The good cycle life performance of the test cell is probably due to the increase in the positive plate thickness after formation as described above. This is because the increase in the plate thickness causes enough compression on the element to prevent disintegration and shedding of the positive active mass (6).…”

Section: N T H E U N F O R M E D State T H E R E W a S N O D I F F E ...mentioning

confidence: 99%

Effect of Anisotropic Graphite on Discharge Performance of Positive Plates in Pasted‐Type Lead‐Acid Batteries

Tokunaga¹,

Tsubota²,

Yonezu³

et al. 1987

For improvement of the discharge performance of pasted-type lead-acid batteries for cycle service use, anisotropic graphite is added to the positive paste, and its effect on the discharge performance of the positive plates has been examined. The 6apacity of the positive plates increased remarkably and also cycle life was improved by the addition of graphite. These effects can be attributed to the increase in porosity of the positive active mass due to expansion of the graphite by anodic oxidation.