A New or Improved Porous Plate, Body, or Electrode.
Year: 1895

page_text: Date of Applicati n, 24th Sept., 1895-Accepted, 23rd May, 1896
COMEDVED DEE
[Communicated from abroad bу JOHN JOHNSON, Manufacturer, of 639 Kent
Avenue, and JAMES HART ROBERTSON, Electrician, of 1287 Fulton Street,
both of Brooklyn, County of Kings, State of New York, United States of
America.]
A New or Improved Porous Plate, Body, or Electrode.
I, WILLIAM HENRY BECK, of 115 Cannon Street, in the City of London,
Consulting Engineer, and Chartered Patent Agent, do hereby declare the nature of
this invention, and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement :-
The present invention relates to an improved porous plate or body for any useful
purpose in the arts, such as for an electrode in a secondary battery, and to an
improved method of making the same.
The invention is designed to produce mechanically what may be termed a porous
plate or body, that is to say, a plate or body which is ramified more or less
throughout its entire structure with pores or cells which act to provide a greatly
enlarged surface so that when used as an electrode in a secondary or other battery,
such increased surface will be exposed to the action of the electrolyte; the degree
of porosity of the plate or body being governed by the uses to which it may be
desired to adapt it in practice.
In carrying out the invention we take a suitable metal, such, for instance, as
lead, and heat it until it is brought to a molten and fluid condition, and then add
to the same a granulated or powdered and artificial or preferably natural porous
substance such as pumice stone, brick dust, kaolin, coral, and the like; such
substance being also preferably an inert substance and thus obviating, when the
plate, for example, is used as an electrode in an electric battery, any local action.
The addition of this granulated substance and its mixture and incorporation with
the metal forms a pasty mass which may be further kneaded, mixed or rolled in a
manner similar to the kneading of flour-dough, or in any other suitable manner
that will obtain the proper incorporation and dissemination of the granulated
substance throughout the mass in as even and uniform condition as is possible. The
mass is then, while in this more or less pasty condition, and with the added granular
material, rolled, molded or pressed into a mold of the required size, according as the
uses to which the plate or body is to be put may indicate.
The porous substance employed as above described contains innumerable air
cells, the air from which is greatly expanded out into the molten metal by the heat
of the latter, thereby producing air spaces therein, or what may be termed an aerated
condition thereof.
While the mixture is in the mold, the mold and the material therein may be
subjected to a slightly elevated temperature sufficient to enable the exterior surface
of the plate or body to be made or become smoother than it ordinarily would without
such additional heating. The now completed porous plate or body may be removed
from the mold and subjected to other treatment or employed directly in any of the
arts as may be desired.
It is advantageous, but not necessary, to add to the lead in the first instance a

page_text: small quantity of tin or bismuth in order that the temperature at which the pasty
condition of the mass will obtain will be lowered a few degrees below that of lead
alone.
When the plate is to be used as an electrode of a battery the finished plate may
be subjected to such action as may be necessary to provide or form throughout its
nechanically produced pores or cells the so-called "active material," which, in the
present knowledge of storage batteries, is necessary to the use of such plate. Thus
the porous plate may be placed in an electrolytic fluid, be connected in circuit with
an electric generator and be subjected to the action of an electric current so that
there will be formed in the usual manner throughout its body such active material,
this active material being produced principally or partly upon the walls of the air
spaces or pores of the plate, both in those spaces which are empty and in those
containing the grains of the porous material.
In practice we have used the metal and porous inert substance in about equal
proportions in bulk, or in other words, a plate weighing, say, one pound fourteen
ounces, will contain about three-quarters of an ounce of granulated pumice stone,
such pumice stone being of the size of ordinary white sand and such as is sold in
the market and known as coarsely granulated punice stone. The quantity of porous
substance added to the pasty mass may be varied according to the degree of porosity
desired.
On account of the great porosity of this plate or body and the large surface
attained and the practicability of obtaining the very large dissemination of the active
material throughout the entire body of the electrode, it is obvious that fewer plates
may be used than usual and yet obtain the same result, and with the added result
of a much lighter battery.
While we have mentioned the use of the porous plate for an electrode of a
secondary or other battery, it is obvious that it has other uses in the arts.
The porous inert substance added to the metal to obtain the porosity described
may without objection remain a part of the finished plate or body, as we have found
in practice that its presence does not detract from the useful functions of such
plate.
We employ the word metal to mean an elemental substance, such for instance as
metallic lead, as distinguished from the oxide of a metal.
Having now particularly described and ascertained the nature of our said inven-
tion, and in what manner the same is to be performed, we declare that what we
claim is :
1. The herein described porous plate or body for electrodes and other purposes
consisting of a mechanical mixture of a metal in its metallic form and an inert
nonconducting porous substance, said plate or body containing air spaces in addition
to those occupied by said substance.
2. The herein described porous electrode plate consisting of a mechanical mixture
of a metal in its metallic form and an inert nonconducting porous substance, said
plate containing air spaces in addition to those occupied by said substance and
containing in its spaces an active material.
3. The herein described porous lead electrode, consisting of a mechanical mixture
of metallic lead and granulated pumice stone.
4. The herein described method of making a mechanical mixture of a metal and
an inert nonconducting porous substance, which consists in heating the metal until
brought to a molten condition and then while in such condition adding the inert
substance to and kneading it with such metal, whereby the air in said porous
substance is expanded and caused to produce air spaces in the fluid metal.
5. The herein described method of making an electrode for a battery, which
consists in making a mechanical mixture of a molten metal and an inert non-
conducting porous substance, and subjecting the mixture to an electric current.
6. The herein described method of making an electrode for a battery, which

page_text: consists in making a mechanical mixture of molten metallic lead and granulated
pumice stone, and subjecting the mixture to an electric current.
Dated this 24th day of September 1895.
W. H. BECK,
115 Cannon Street, London, E.C., Applicant.