[ARC5] Batteries That Do Not Corrode?

[Tom Lee]

The notion of a "depolarizer" has a curious history. Manganese dioxide 
is a strong oxidizing agent and was originally added to the electrolyte 
in carbon-zinc batteries to scavenge the hydrogen liberated during 
normal operation. Hydrogen increases the cell resistance, so getting rid 
of it is important. Until it is removed, the cell will have less 
available energy, explaining why, after a heavy discharge, a carbon-zinc 
cell takes time to recover. This recovery time would be much longer were 
it not for manganese dioxide. It took an embarrassing number of years to 
realize that any chemical strong enough to oxidize hydrogen was itself 
acting as the cathode. The carbon rod is actually just a conductive 
terminal; it does not participate in the energy-releasing reactions. I 
fully expect Madison Avenue someday to relabel these old batteries as 
"manganese-chloride" cells to induce consumers to buy them.

Adding mercury to carbon-zinc batteries was occasioned mainly by a 
desire to reduce the rate of dissolution of the zinc can. I don't know 
what substitutes are now being used to provide corrosion resistance in 
mercury's stead.

--Tom

-- 
Prof. Thomas H. Lee
Allen Bldg., CIS-205
420 Via Palou Mall
Stanford University
Stanford, CA 94305-4070
http://www-smirc.stanford.edu
650-725-3383 (public fax; no confidential information, please)

On 6/9/2018 7:38 PM, Brooke Clarke wrote:
> Hi Wayne:
>
> Not quite.  Modern batteries, like Ever Ready/Energizer, are much 
> better than prior designs.
> In 1991 the EU banned Mercury in products.  This immediately showed up 
> as a ban of Mercury batteries ( all the military batteries with model 
> numbers of BA-1000 to BA-1999) plus civilian Mercury batteries.
> http://www.prc68.com/I/TS183.shtml#Hg
> But . . . Mercury was also used on the carbon rod of the Carbon-Zonc 
> battery as a depolarizer and it took a lot of work to replace that.
> Modern batteries have much lower internal resistance, i.e. they can 
> supply much higher currents (Flash Amps) than the older chemistries.
> http://www.prc68.com/I/No6.shtml#FA
>
> There's a YouTube video showing that if you connect a series string of 
> AA cells (maybe 10 of them?) and put that in parallel with a dead car 
> battery for a few minutes, you can start the car.
> -- 
> Have Fun,
>
> Brooke Clarke
> http://www.PRC68.com
> http://www.end2partygovernment.com/2012Issues.html
> -------- Original Message --------
>> What's old is made to seem new. Yet again.
>>
>> Wayne
>> WB4OGM
>>
>> -----Original Message-----
>> From: Bill Cromwell <wrcromwell at gmail.com>
>> To: arc5 <arc5 at mailman.qth.net>
>> Sent: Sat, Jun 9, 2018 6:39 pm
>> Subject: Re: [ARC5] Batteries That Do Not Corrode?
>>
>> Thanks,
>>
>> So it's all hype and slight of hand from Madison Avenue.
>>
>> 73,
>>
>> Bill KU8H
>>
>> On 06/09/2018 08:00 PM, Tom Lee wrote:
>> > Yes, that's correct. Ammonium chloride ("sal ammoniac" in oldspeak) is
>> > the electrolyte in carbon-zinc batteries.
>
>
>
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