Battery chemistry "activation"

[Phaserburn]

Battery chemistry \"activation\"

I've read elsewhere on CPF about how when alkalines are first used for a few minutes that it essentially starts a deathspin for the battery to self discharge it's power over the next months and circumvents the years of "shelf life".
1. Is this true of today's alkalines?
2. How about lithium 123's?
3. How about titaniums or other chemistry?
I know NiMH discharge starting when they leave the charger. I didn't see any info on this on the manufacturer's websites.

I want to give my Dad a new light. Besides size and other operational specs that matter to him, one of his biggest gripes is the flashlight=tube to hold dead batteries. He wants to be able to use it sporadically but have life when he needs it. I know he'd get that from lithiums if not used, but what about when used intermittently? /ubbthreads/images/graemlins/help.gif

 

[Doug S]

Re: Battery chemistry

I too remember seeing that said somewhere on CPF. I am a bit skeptical about this claim. I have never seen any mention of this phenomenon in any technical literature and I've read a lot of it. If there is any truth to it I would like to see someone provide a citation to a creditable reference.

 

[shiftd]

Re: Battery chemistry

Well, Doug.
I don't have any citation handy, but I recall (like what i told in the other threads) that the shelf life of the button Zinc is whole lifetime as long as the battery had never been used. I think this is also applies to the other.
As for Phaserburn question, the best way to ensure that your dad always get light out of his flashlight is to recycle and test the battery every 6 months. It is true that the battery will undergoes self discharge after you use it the first time, but the rate is not constant and eventually will decrease as the battery discharge itself.
well, enough babbling.
Sorry Doug of not giving a citation or any creditable reference, but it is better to believe now than to regret later, right?

 

[Doug S]

Re: Battery chemistry

[ QUOTE ]
shiftd said:
Well, Doug.
I don't have any citation handy, but I recall (like what i told in the other threads) that the shelf life of the button Zinc is whole lifetime as long as the battery had never been used. I think this is also applies to the other.
As for Phaserburn question, the best way to ensure that your dad always get light out of his flashlight is to recycle and test the battery every 6 months. It is true that the battery will undergoes self discharge after you use it the first time, but the rate is not constant and eventually will decrease as the battery discharge itself.
well, enough babbling.
Sorry Doug of not giving a citation or any creditable reference, but it is better to believe now than to regret later, right?

[/ QUOTE ]

If you are extrapolating from air-zinc button cells to alkalines then I would say that no, it is not right to "believe now". Air-zinc button cells actually use oxygen from the air to react with the zinc. They are packaged with a seal to exclude air until they are to be used. At this time the seal is removed to admit air into the cell to enable the reaction.

 

[Ray_of_Light]

Re: Battery chemistry

Alkaline batteries uses powdered zinc at negative side of the battery. As is documented in any inorganic chemistry book, the zinc is a metal with a special property: it is corroded from acid AND from alkalis.
Heavy duty (zinc carbon) batteries uses ammonium chloride or zinc chloride as electrolyte, which is a "neutral" salt and doesn't attack the zinc.
With alkalines is a whole different story. The electrolyte is constituted from potassium hydroxide, a strong alkaline used in liquid form, because it has a very low electrical resistance.
The electrolyte would dissolve the zinc in short time, if no precaution are taken.
Until 10 years ago or more, manufacturers were adding mercury to the zinc, and the "alloy" so formed was indefinetively protecting the zinc from the potassium hydroxide.
When mercury had to be removed from commercial batteries, manufacturers started using various additives in the zinc and the electrolyte, to form a "passivation" layer (which is a kind of inert oxide) around the zinc.
This "layer" is present at manufacture and guarantees the expiration date of the battery.
This layer dissolves with use (while adding some "inertia" to the battery "readiness") of the battery, and reforms when the battery is idle. Of course... the reformed passivating layer is "weaker" of the original, and becomes even weaker with the use of the battery.
Some off-brand alkalines have this layer not formed at all after first use. They are "timed batteries"...

This problem affects only alkaline batteries. High-end alkalines uses purer chemicals, and are less prone to the self discharge problem. The problem is strongly worsened from high temperatures.

Titanium is a chemical used to further reduce the internal resistance of the battery. It is added to the manganese dioxide (positive side).

I cannot provide any reference, since these problems are not mentioned at all on batteries manufacturer's sites. I gained these "information" by comparing what is known of manufacturing technology with some "in house" experimentation... that anybody can independently verify.

Regards

Anthony

 

[Tomas]

Re: Battery chemistry

Here's a list of references (via google search) on the effect of the passivation layer on lithium battery shelf life and performance.

Search: lithium+battery+shelf+life+passivation

I haven't spent the time to search in detail for the one, specific, all-knowing reference, though I recall reading several when lithuim's were first coming out for commercial use a couple of decades or so ago ... /ubbthreads/images/graemlins/ooo.gif

I'm sure there are numerous references to the passivation layer or film that normally forms on one of the electrodes in a lithium cell, which greatly reduces it's self discharge.

Forming this film does take some energy from the cell, and constantly re-forming the film is one of the mechanisms that reduces the shelf life of lithium cells after use. Also, while the film is forming additional energy is dissapated (self discharge) until the film again fully protects the cell.

Short form: The passivation layer formed on an inactive lithium cell's electrode greatly extends it's shelf life by insulating the layer and greatly reducing self discharge.

When a lithium cell is used, there is a delay for it to come to full power (it really isn't instantaneous) while this film is destroyed. When the cell again goes inactive, it uses some of it's energy to rebuild this passivation film to the same thickness it was before at a rapid rate, then drops back to it's very tiny energy use as it continues to thicken the film (yes, this uses cell energy and is why the shelf life is "long" not "infinite").

A cell that is constantly building and re-building it's passivation layer at the higher rate (to get back to it's "remembered" thickness) uses a bit more energy than one that stays at the very low un-used rate. This reduces the overall energy that can be drawn from the cell for external use, and therefore "shelf life."

IIRC it was actually found that an extremely low, continuous, micro-Amp discharge rate prevents the film from reforming, and actually greatly reduces the life of the cell because of self-discharge.

The rate of discharge while being used, even in short bursts, can seriously affect the longevity of the cell and it's total capacity because of permanent effects to the forming and re-forming of the passivation layer. (High discharge rates can form a "permanent" passivation film during recovery that can prevent the use of the cell's energy.)

Obviously, the search criteria for this Google search can be changed, and an obvious change would be from "battery" to "cell" or "batteries" or "cells." Another would be to change from "shelf life" to "shelflife," etc. Minor search criteria changes like this can drasticly change the results.

I'm going back to bed - dredging disused information out of the deeper recesses of a damaged memory was too much work. /ubbthreads/images/graemlins/icon23.gif

Hope it helped!

/ubbthreads/images/graemlins/jpshakehead.gif