User:KhalidH/Electrode production options

There are many different ways to make the physical electrodes given active material. The Edison process involved tubes packed with powdered active material, nickel or graphite flakes, molasses and some additives such as cobalt hydroxide (see other reactions and additives section) under about 4000 PSI and with about 8 grams of the mixture per tube, each of which was about a quarter of an inch in diameter and formed of nickel plated perforated sheet metal and reinforced with rings of metal in some areas. See his patents for details. These are then connected together to form the nickel electrode. He made the iron is in either a similar way or by compressing iron active material into a brick with copper crystals, mercury and other additives.

A very similar process is was still used as lately as the nineties by some manufactures, who may still be using it. For some reason they use smaller tubes only a few millimeters wide.

The changhong batteries are pocket-plate type. Verification is needed on exactly what pocket plate indicates. It can include tubular but there seems to be a distinct method as well in use which involves essentially denting the surface into pockets, much like a tv dinner tray. This could be easier and cheaper.

Other current collectors that are described as being or having been used commercially are:

• Nickel fiber mesh and paper
• Sintered nickel powder
• A foil or mesh on nickel or nickel plated steel which is covered in powder then sintered to bond the particles to it, increasing surface area
• Foil (for teflon bonded) can be bend or scored or etched to increase surface area
• Nickel foam- nickel powder is mixed with e.g. polyurethane foam particles the surface of which they coat, packed together and heated at greater than 700 degrees, removing the polyurethane and leaving the nickel.
• Nickel plated steel wool

Others described in patents but which don't seem to be used:

• Carbonized polymer material, heat some polymers to 900 degrees and they carbonize into a relatively durable and conductive material which is chemically compatible more or less with both the nickel and iron electrodes. Carbon particles of activated carbon are mixed in too.

There may be others as well

Other ideas

Getting the material onto the substrate

Active material includes additives etc.

Used commercially: Mix the active material with teflon or another hydrophobic plastic particles, graphite particles, and some elastomer and a thickener. Exact compositions described in patents. Apply to mesh or foil and press hard, like 700 kg per cm2.

Mix it into a paste and apply to a mesh or foam by running the foam or cloth through rollers along with the paste. Apparently it stays put in the foam without any additives like thickeners or binders though I would have though it would slowly fall out. de-emulsifiers, thickeners and other additives are sometimes used to make the details of production easier.

Vacuum impregnation

A common method called vacuum impregnation is to dip the mesh or foam in melted nickel nitrate and then into hot sodium hydroxide solution, converting the nitrate to hydroxide. Presumably it is done under a vacuum else the air in the foam would prevent entry of the liquids.

Electrochemical impregnation

There are several ways to do it and a chemist could probably come up with more, but basically the right nickel compound precipitates out of solution in fine particles on the surface of the nickel matrix. The source of the nickel can be either the metallic nickel matrix (beefed up with extra nickel of course) or the surrounding solution.

Other methods

Described in patents but not apparently used: In some cases the active material can be mixed with e.g. nickel fibers or fibers of the polymer to be carbonized, then the whole thing heated, bonding the fibers, flakes, whatever, together into a continuous mesh. The heating does not damage the active material if it is formulated right and done in the right atmosphere (not hard though).