Subsurface Area

By Hugh Abner
[44 Years and Counting Manufacturing Batteries and Battery Machinery]

Some of us that mostly have dwelled in our battery world by melting Pb and making mud do not normally stop and consider the importance of the surface area. It is an accepted fact to us when we are assembling a battery with “Low” plates versus “Tall” plates that surface area is part of an over-all kind of thing. Generally though, we pass it off as making cheap batteries versus expensive ones.

We probably have at times tried to make the argument that the cheap ones could be the better of the two. This would come from the understanding that the plates are only good when totally immersed in electrolyte. Therefore a cheaper battery with short but immersed plates would perform better than an expensive one that had a low electrolyte level causing exposed plates and a loss of active material surface area.

Actually in the break rooms we had little discussions concerning the funny difference between Ford and Chevrolet plates. If you have forgotten, a Ford plate is, (Was), narrow and tall with the Chevrolet plate being wide and short but both measure out to the same surface area. In these discussions, depending upon which car we were fans of, we would explain to anybody listening that Ford’s narrow battery allowed them to put more engine under the hood. That was ignorant if not malicious talk. With that argument being a failure the Chevrolet folks would explain that with the wide short plate an allowance was created for the liquid level of the electrolyte to remain above the plate’s active material for a longer period of time between battery maintenance duties. I, for one, wonder what the break room discussions can even be about today since batteries are maintenance free. My present battery is certainly maintenance free since I simply have to replace it every 2 years right on schedule just like an advertised 5 year battery should be. Seriously though, note that I drive a Jeep and I blame this shortfall on two things: more than likely it is the Jeep peoples fault, (I love them still though), plus my battery supply people just throw in another without complaint and charge me very little for the replacement.

Here with surface area being the subject I feel it important to bring to the attention of true battery people, not you accountants and lawyers that hang around, some astounding surface area news. No, it is not Pb-Acid news for it is all about the new kids on the block: lithium ion and nickel-metal hydride.

What I have learned comes from an article in The Economist. I probably cannot just copy it and present it here for the pleasurable reading that it is but you can find it in the March 26th to April 1st issue of 2011. Yes, in the Science and Technology section. Recently in this blog I referred all of you to another battery interest which this great magazine gave us. I hope you read it for in it Einstein let us lean on him once more.

This article is great in two ways. First it more than explains the simplicity of all batteries within its first two paragraphs and then by the third it has us understanding how to create massive amounts of surface area in dense metallic material.  A Doctor Paul Braun from the University of Illinois is the scientist involved. In this article there is a description of taking a very dense material, electrodepositing it onto spheres of polystyrene. Then all of it is heated up to melt away the polystyrene and a highly porous battery substrate is created. The accompanying electrolyte has a miraculous quantity of pores to dwell in.

Now, I know, I probably will hear from thousands telling me how we have done this for years with Pb before we even knew about things like lithium. Please though, tell me again. I would like to hear from you.

I can tell you that on the back side of having material so massively porous which in turn lets us recharge a battery – in their words – (“In the time it takes to fill a gas tank”), is a big problem. The electrical conductors have to handle huge amperage loads. That’s right: the conductors to the battery and inside it.

So, check out this science information provided by The Economist. Being that you are one of us you will enjoy it.

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