Why do batteries inevitably wear out?

It isn't due to sulfation. The idea that sulfation causes batteries to wear out has been consistently rejected by scientists and battery manufacturers. Sulfation is caused by undercharging. Undercharging is common. The cure is obvious and very simple. Charge the batteries as soon as possible after use.  

Research that led to the discovery of Batteryvitamin identified a specific mechanism inherent in lead-acid motive power batteries responsible for batteries wearing out - at the same time provided a solution to defeat the wearing out process.

Besides being effective at storing electrochemical energy, when operated long term, surprisingly, battery cells additionally behave as ultra low efficiency electroplating cells.

In an electroplating cell, metal at a positive electrode is corroded, becomes dissolved and is electrolytically deposited on a negative electrode.

In a battery cell this results, over time, in disintegration of the vital metallic grid structures of the positive plates, causing the active material to lose its support and to fall out.

The way in which lead-acid battery cells work causes the grids of the positive electrodes to be subjected to quite severe corrosion. Consequently, the outer layer of the lead metal of the grids becomes converted to a lead oxide which, fortunately, slows down the effects of corrosion. The lead metal of the grids is usually alloyed with a little antimony, to form a passivating layer over the lead metal, in turn significantly improving the resistance against corrosion. (In maintenance-free batteries the grid lead is alloyed with calcium. Lead-calcium offers little or no resistance to corrosion, hence these batteries react very badly to overcharging.)

Comparative testing based on Battery Council International Deep Cycling Battery Test Procedure (5/93), in which specific batteries were dosed with the Batteryvitamin substance and the remainder received none, (see Graphs 1 & 2), and subsequent teardowns and examinations, convincingly demonstrated that electroplating had been behind the wearing out process.

The only way electroplating could have occurred is for some of the lead metal in the positive grids to have become dissolved in the battery acid electrolyte, despite the protection provided against corrosion at the positive grids.

The corrosion aspect has long been accepted but the electroplating aspect appears to have been subject to a great deal of conjecture within the battery industry for many years.

It appears to have been argued that since lead is a comparatively insoluble metal in the context of lead-acid batteries that, therefore it will not electroplate. In fact, electrolytic refining of lead is well established using a lead hexafluorosilicate electrolyte. Lead is commercially electroplated using lead tetrafluoroborate, lead methanesulfonate and lead pyrophosphate electrolytes, (reference 1)

The solubility of the electrolytic lead is in the order of 600 grams per liter and that of the battery lead in sulfuric acid 4 milligrams per liter, (reference 1 & 2.)

From an electroplater's technological point of view, anodic lead will become dissolved in an acidic electrolyte in the presence of oxygen. Oxygen is given off by the positive electrodes during normal overcharging, (ironically, a degree of overcharging is necessary to prevent sulfation), resulting in lead (as well as antimony at 15 milligrams per liter solubility), becoming progressively solubilized at the end of each successive charge. Has the industry perhaps been too conservative in the past to follow through on this aspect?

What it all boils down to is that even though battery lead may be about 150,000 times less soluble than electrolytic lead, after about 3-8 years in service, a lead-acid motive power battery will have been exposed to an amount of electroplating at least comparable to the work performed by electrolytic refining and electroplating cells over a period of several hours.

The benefits provided by Batteryvitamin are superior to the benefits provided by rubber separators, for example, Microporous Ace-Sil* and Flex-Sil*, and dramatically superior to Cellforce*, Daramic HD* and Entek's experimental industrial separators containing very fine recycled truck tire rubber particles, (*registered trademarks), (references 1.  2.  3.).

Batteryvitamin has a very specific functionality and is thereby able to cut down electroplating and to extend battery life without otherwise significantly affecting battery operation, (see Life Expectancy A B C D.)
 

REFERENCES:

SCHLESINGER, M and PAUNOVIC, M, "Modern Electroplating", The Electrochemical Society, Inc., (John Wiley & Sons, New York, Fourth Edition 2000), References 1, pp 362 - 365; 3, pp 355 - 367.

BODE, H, "Lead Acid Batteries", (John Wiley & Sons, New York, 1977), References 2, pp 25 - 32; 4, pp 238 - 242 & 338 - 345.

(1.) PAIK, SL and TERZAGHI, G, "Rubber Separators for Tomorrow: Performance Characteristics and Selection Guide", (1994), Amerace Microporous Products, Inc., website PDF - www.mplp.com/TechSheets/tomorrow.pdf . (2.) Daramic LLC publication, website PDF - www.daramic.com/uploads/documents/HD.pdf . (3.) Entek International LLC flyer, website PDF - www.entek-international.com/Publications/entek_industrial_flyer.pdf