AN IMPROVED PROCESS OF " FORMING OR PREPARING ELECTRODES FOR SECONDARY BATTERIES
Year: 1882

page_text: "
LETTERS PATENT to Alexander Melville Clark of the firm of A. M and
W. Clark of 53, Chancery Lane, in the County of Middlesex, Patent Agents.
for an invention of AN IMPROVED PROCESS OF "
FORMING OR PREPARING
ELECTRODES FOR SECONDARY BATTERIES Communicated to him from abroad
by Jean Marie Anatole Gérard-Lescuyer of Paris, France, Engineer
PROVISIONAL SPECIFICATION left by the said Alexander Melville Clark
at the Office of the Commissioners of Patents on the 7th June 1882.
<<
"
"
ALEXANDER MELVILLE CLARK of the firm of A. M. & W. Clark of 53 Chancery
Lane in the County of Middlesex Patent Agents, "AN IMPROVED PROCess of
FORMING OR PREPARING ELECTRODES FOR SECONDARY BATTERIES. [Commu-
nicated to him from abroad by Jean Marie Anatole Gérard-Lescuyer of Paris,
France, Engineer]
Most salts of which the radicle is an oxide acting as an acid, are powerful
oxidising agents, and this Invention consists in the application of this remarkable
property to the rapid formation of secondary pairs.
In an electro chemical bath containing one or more of these salts, I substitute
for the soluble anode the secondary pair to be formed. The two poles of this pair
are connected together and attached to the positive pole of the generator of
electricity which is to decompose the bath, and at the negative pole I place a plate
of any suitable metal or of carbon. Under the action of the current the negative
pole becomes metallised whilst the lead forming the anode becomes rapidly oxidised
at the expense both of the bath and of the decomposed salt whose oxygen goes to
the positive pole. The application of heat augments or hastens these results.
Manganates, ferrates, alkaline chromates, zincates, stannates, antimoniates, &c,
possess this property but those salts which are most convenient of use are plumbates
and plumbites. For the sake of economy I generally use sodic or potassic plumbite
which I prepare in the following manner :-
In an alkaline lye at 32° to 35° Beaumé I dissolve by boiling, 15 to 20 grammes
of massicot or litharge per litre (= about 1000 to 1400 grains per gallon.) When

page_text: this combination is effected, the bath is fit for use and as soon as it has cooled
down to 70° C. I immerse therein the secondary pair which I attach to the positive
pole of the electrical generator and for greater simplicity I use the containing
vessel itself as the negative electrode. The action commences at once; the sides
of the vessel become covered with non-adherent spongy lead and the plates of lead
composing the pair become covered with a coat of a fine red color which is
plumbate of protoxide of lead or minium. If the temperature of the bath falls to
about 15° C. minium is no longer formed at the positive, a brown coat of plumbic
acid being then obtained.
The hot method is the most rapid, a few hours, 3 or 4 at the outside, sufficing
to transform completely through, a plate of lead 2 millimetres (=1/12 of an inch)
thick. The oxide thus formed is crystalline and strongly adherent to the lead
which it envelops like a sheath.
If whilst these effects are being produced, the temperature of the bath be again
raised to boiling, the oxide formed is dissolved and the lead is attacked and
diminishes in thickness until it disappears if the volume of the liquid is sufficient.
It is therefore necessary not to exceed the temperature above indicated. This
result enables one however to reconstitute the bath for by reversing the direction
of the current and by replacing the pair by a very small metal plate, the spongy
lead which in the first case was deposited on the sides of the vessel, becomes
oxidised in turn and redissolved in the bath which is then ready to recommence a
fresh oxidising operation. A small excess of massicot or litharge is advantageous
to compensate for waste and maintain the bath always at the point of
saturation.
As above mentioned the oxide formed in the cold is plumbic acid; it has a
peculiar velvety aspect and it also adheres strongly to the lead. In this latter
case the operation is longer and requires a charge of at least 10 to 12 hours.
The current required need not be of great intensity, the bath being a very good
conductor.
When the coat of oxide is considered sufficient, the pair is withdrawn from the
bath and plunged into an earthen pot of hot or cold water which is renewed two
or three times so as to eliminate the last traces of alkali, or I may immerse in
slightly acidulated water which saturates the remaining soda and afterwards wash
in plain water.
The bath should be kept absolutely clean and care taken to prevent any organic
matter falling in as this would cause its decomposition. It has also been remarked
that certain highly sulphurised caoutchoucs cause the formation of sulphides which
immediately destroy the bath. By this simple process I am enabled in less than
3 hours to form a pair composed of two plates of lead 3 feet 3 inches long by
8 inches broad which in 20 minutes at the first charging has stored a current of
45 amperes.
I am also enabled by this process to coat with lead or with oxide of lead either iron,
copper, or other metals in plate, wire, granular, or powdered form, as likewise wire
cloth made of these metals and gilt or platinised if necessary.
In the same way I
may coat plates, sticks, or broken fragments of carbon, whereby I am enabled to
reduce to a minimum the weight of the accumulator and at same time ensure the
maximum of active surface.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Alexander Melville Clark in the Great Seal Patent Office on the
7th December 1882.
"
"
ALEXANDER MELVILLE CLARK of the firm of A. M. and W. Clark of 53 Chancery
Lane in the County of Middlesex, Patent Agents. "AN IMPROVED PROCESS, OF
OR PREPARING ELECTRODES FOR SECONDARY BATTERIES
A commu
nication to me from abroad by Jean Marie Anatole Gérard-Lescuyer of Paris,
France, Engineer.
" FORMING
Most salts, of which the radicle is an oxide acting as an acid, are powerful
oxidising agents, and this Invention consists in the application of this remarkable
property to the rapid formation of secondary pairs.
In an electro chemical bath containing one or more of these salts, I substitute
for the soluble anode the secondary pair to be formed. The two plates of this pair
are connected together, and attached to the positive pole of the generator of
electricity which is to decompose the bath, and to the negative pole I connect a
plate of any suitable metal or of carbon. Under the action of the current the
cathode becomes metallised whilst the pair of lead plates forming the anode becomes
rapidly oxidised at the expense, both of the bath and of the decomposed salt whose
oxygen goes to the anode. The application of heat augments or hastens these
results. Manganates, ferrates, alkaline chromates, zincates, stannates, antimoniates,
&c, possess this property, but those salts which are most convenient of use are
plumbates and plumbites. For the sake of economy I generally use sodic or
potassic plumbite which I prepare by dissolving massicot or litharge in a boiling
alkaline lye at 32° to 35° Beaumé in the proportion of 15 to 20 grammes of
massicot or litharge per litre (= about 1000 to 1400 grains per gallon). A small
excess of massicot or litharge is advantageous to compensate for waste and maintain
the bath always at the point of saturation. When this combination is effected the
bath is fit for use, and as soon as it has cooled down to 70° C. I immerse therein
the secondary pair which I attach to the positive pole of the electrical generator,
and for greater simplicity I use the containing vessel itself as the cathode. The
action commences at once; the sides of the vessel become covered with loosely
adherent spongy lead and the pair of lead plates become covered with a coat of a
tine red color which is plumbate of protoxide of lead or minium. If the tempera-
ture of the bath falls to about 1.5° C minium is no longer formed at the anode, a
brown coat of plumbic acid being then obtained. The hot method is the most
rapid, a few hours, 3 or 4 at the outside, sufficing to transform completely through
a plate of lead 2 millimetres (= 1/1, of an inch) thick. The oxide thus formed is
crystalline and strongly adherent to the lead which it envelops like a sheath.
If, whilst these effects were being produced, the temperature of the bath were to
be again raised to boiling, the oxide formed would be dissolved and the lead would
be attacked and diminished in thickness until it disappears if the volume of the
liquid is sufficient. It is therefore necessary not to exceed the temperature above
indicated. This result enables one however to reconstitute the bath for by reversing
the direction of the current and by replacing the pair by a very small metal plate,
the spongy lead which in the first case was deposited on the sides of the vessel
would become oxidised in turn and redissolved in the bath which would then be
ready to recommence a fresh oxidising operation.
As above mentioned, the oxide formed in the cold is plumbic acid; it has a
peculiar velvety aspect and it also adheres strongly to the lead. In this latter case
the operation is longer and a battery made up with plates coated with plumbic

page_text: acid would require a charge of at least 10 to 12 hours. The current required need
not be of great intensity, the bath being a very good conductor. When the coat of
oxide is considered sufficient, the pair is withdrawn from the bath and plunged into
hot or cold water which is renewed two or three times so as to eliminate the last
traces of alkali, or I may immerse in slightly acidulated water which saturates the
remaining soda, and afterwards wash in plain water. The bath should be kept
absolutely clean and care taken to prevent any organic matter falling in as this
would cause its decomposition. It has also been remarked that troughs or cells
made of certain highly sulphurised caoutchoucs cause the formation of sulphides
which immediately destroy the bath. By this simple process I am enabled in less
than 3 hours to "form a pair composed of two plates of lead 3 feet 3 inches long
by 8 inches broad capable in 20 minutes at the first charging of storing a current
of 45 ampères.
"
I am also enabled by this process to coat with spongy metallic lead or with
oxide of lead either iron, copper, or other metals in plate, wire, granular, or
powdered form as likewise wire cloth made of these metals and gilt or platinised
if necessary. In the same way I may coat plates, sticks, or broken fragments of
carbon whereby I am enabled to reduce to a minimum the weight of the accumulator
and at same time ensure the maximum of active surface.
With the plates or electrodes "formed " by the process hereinbefore described I
construct accumulators in the usual way, either by rolling up the plates of lead into
a spiral form and separating them by caoutchouc, wood, felt, or other suitable
insulating material and immersing them in water acidulated with one-tenth of
sulphuric acid, or by arranging flat, corrugated or undulated lead plates in a
vertical position very close together and insulated from one another and connecting
the alternate plates in two series in the usual way.
In the process of formation herein before described, I include under the terms
plate or electrode for accumulators, lead in sheets, sticks, granules, or other form,
and I reserve the right to apply the said process of formation to existing
accumulators.
Having described the nature of the said Invention and the manner of performing
the same, I declare that what I claim as the Invention to be protected by the
herein-before in part recited Letters Patent is.
The "formation" of the plates or electrodes of secondary batteries by the action
of an electric current on an alkaline solution of suitable metallic salts in which the
plates or electrodes to be formed are immersed as herein described preparatory to
transferring the plates or electrodes to an acid solution to be charged in the ordinary
way,
In Witness whereof I the said Alexander Melville Clark have hereunto set