Improvements in and relating to Secondary or Storage Batteries.
Year: 1892

page_text: Date of Application, 16th Dec., 1892-Accepted, 28th Jan., 1893
COMPLETE SPECIFICATION.
Improvements in and relating to Secondary or Storage Batteries.
I JAMES YATE JOHNSON of 47 Lincoln's Inn Fields in the County of
Middlesex Gentleman do hereby declare the nature of this invention (which has
been communicated to me from abroad by Auguste Marie Michel citizen of the
French Republic and resident of Paris France) 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 the preparation of the so called "active material "
or secondary or storage batteries that is to say material readily oxidized and
deoxidized and also to the formation of the negative elements of such batteries.
To produce lead in a spongy or "frothy" condition so that it shall retain its
cellular structure and be readily permeable by the battery fluids, I proceed as
follows.
(1) An alloy of lead and another metal which is capable of elimination such as
zinc is formed in the proportion of the metals being preferably ninety six parts by
weight of lead to four parts by weight of zinc but other proportions may be used if
deemed advisable, or suitable for the purpose.
(2) The alloy thus formed is disintegrated which may be effected by mechanical
or physical means for example it may be reduced by cutting tools to shavings,
gratings or the like or it may be reduced by melting and then agitating the mass
while cooling, so as to reduce it to a granular or pulverulent condition.
(3) The alloy thus reduced to a state of division is treated by an acid preferably
sulphuric acid the effect of which is to combine with the zinc forming a soluble
compound such as a sulphate of zinc which can afterwards be eliminated by washing
although other means of elimination may be resorted to such as electrolysis for
example in an acidulated bath forming therein with a metal (for instance copper)
in the form of a plate or in other suitable form a negative pole upon which the zinc
after decomposition will be deposited.
The last operation causes the formation in and through the mass of a large
quantity of gas which causes a foaming or frothing and a distending of the mass by
the formation of cells, with thin walls which do not collapse but are easily com-
pressible, even by hand.
This honey-combed lead is employed for the manufacture of plates for secondary
or storage batteries as follows. It may be spread upon lead plates or supports (in
which case there being no adhesion the plate would have to be kept in a horizontal
position) or it may be slightly compressed by pressure (which should not exceed
50 kilos. per square centimeter) into the apaces of skeleton supports or between two
or more such supports forming intermediate cushions as it were, or into forms of
briquettes which may be filled into the spaces of corresponding shape left in the
support for the reception of the active material, or the briquettes may be strung
upon or between lead rods, which may be clamped together to form a plate. The
briquettes may also be placed in moulds in which the frame or support is formed
around the briquettes by molten lead poured into the mould. Other methods may
be found expedient to make plates with the substance prepared as aforesaid an
essential point being that it shall be properly exposed to the action of the electrolyte
of the battery so that the said electrolyte may penetrate throughout the whole mass.
My foreign correspondents has attempted to accomplish this result by forming the
mass by compression of granular or pulverulent lead and zinc alloy and eliminating
therefrom the zinc, but has found that the effect of climination from the compressed
mass creates a tendency to explode and break up the mass so as to render it liable
when exposed to the action of the electrolyte to crumble or break up and particles to
become detached and drop to the bottom of the battery vessel.

page_text: Plates constructed as herein before described retain their adhesiveness during the
operation of the battery and another important advantage of this present invention
is that as now according thereto a maximum pressure of 50 kilos. per square centi-
meters is used whereas formerly it was necessary to use a pressure of from four to
Eix times greater and consequently great economy in power and tools is effected.
In the use of the lead-zinc battery there is practical difficulty due to the loss of
charge by spontaneous dissolution of the zinc on open circuit (deposited on the
negative electrode).
Attempts have been made in various ways to diminish or remove this objection
such as by reducing the dimensions of the surface of the negative element or by
amalgamating the surface of a lead plate or by using porous vessels or by the
employment of special exciting solutions. In some of these batteries when charged
the electrolyzed zinc finding upon the negative plate an insufficient quantity of
mercury amalgamates itself imperfectly and therefore dissolves spontaneously after
charge even while the circuit was open.
My foreign correspondent has observed that to prevent the zinc from being
attacked by the acidulated liquor the quantity of mercury present would require to
be quite considerable for instance about equal proportions by weight of zinc and
mercury. This proportion however is not absolute as will be hereinafter shewn. It
is therefore desirable when a lead-zinc battery is being charged that the zinc
deposited upon the negative plate shall as electrolysis proceeds find a sufficient
quantity of mercury in order that it may thereby become inattackable by or
protected against the action of the acidulated water while the circuit is open.
During the discharge however the zinc becoming dissolved forms a soluble
sulphate of zine the effect of which is a decrease of the zinc in the negative
electrode and the mercury which was allied to or amalgamated with that metal is
set free. The mercury should not fall to the bottom of the vessel or receiver
because then its effect would be lost when the accumulator is charged again to
become amalgamated with the zinc which proceeds from the decomposition of the
sulphate. It is therefore necessary for the best results that during the charging of
the battery electrolyzed zinc shall as fast as it becomes deposited be in contact with
an abundant quantity of mercury in order to form with it a strong amalgam and
further that the mercury necessary for this powerful amalgamation shall not be
liable to drop off the negative plate when the battery is discharged. It is therefore
necessary and important that the mercury should as it were be immobilized or held
in place in or upon each negative plate and should be distributed or spread over
the whole surface as evenly as possible.
The object of this part of the present invention is to attain these essential or
desirable conditions and consists in the means substantially as hereinafter described
of depositing the zinc while the battery is being charged upon a layer of amalgam
(zine or other metal) sufficiently rich in mercury to yield all the mercury that may
be necessary to combine with the electrolyzed zinc.
The said means consists of accumulator plates which are produced in the manner
substantially as follows:-
It is well known that a combination of a metal and mercury may be effected at
high temperature, and that when the proportion of mercury is not too great the
alloy may be moulded into any form and solidified by cooling. Plates may
therefore be formed by this means, but they are brittle.
To obviate this defect and to make plates, tubes or rods of relatively small
thickness, yet of sufficient solidity I consolidate the alloy by mechanical means
upon or into or around devices such as cores skeleton frames, open work supports or
the like, which may be buried in or applied outside the mass before, during, or after,
the moulding of the plate. These alloys rich in mercury, may be made in varying
proportions. I have found for instance that the zinc amalgam containing one part
by weight of zinc, to from three to four parts by weight of mercury, are sufficiently
solid to be thus employed.
The following may be the procedure. Take sufficient. mercury for the quantity

page_text: of zinc used to make an amalgam of pasty consistency, but not more than is
necessary to have it solid at the ordinary temperature. This alloy when slightly
compressed, becomes again for the time being pasty and thus constitutes an
amalgam which can be spread over and squeezed into the meshes of a support made
of metallic wire netting, or gauze, or a skeleton or open work frame of any suitable
or convenient form. Rigid and solid plates are thus produced that have a very
great electric capacity, which may be determined by the weight of zinc which may
be usefully deposited.
The last described proceeding may be reversed; that is to say upon the amalgam
rich in mercury, zinc resulting from the decomposition of the sulphate of zinc may
be deposited until its weight at the end of the charge will equal that of the mercury
in the plate, or from the plate containing equal proportions of mercury, and zinc,
enough may be eliminated by discharge of the accumulator to correspond with the
quantity of electrical work which the plate ought to perform.
Finally, if in the aforesaid methods of forming what may be called the initial
amalgam (which so to speak, is only a reservoir or mercury) a metal be used which
is electro-negative with respect to that in solution, identical results may be
obtained.
Thus in the present case (lead and zinc accumulator) the initial amalgam may be
formed with tin, lead, copper, silver or the like.
Application of plates thus produced may be made in any system of accumulators
in whole or in part to elements which require powerful amalgamation, the metal
serving as the base being changed according to circumstances.
The plates may be of any suitable form and may be arranged vertically or
horizontally or at any angle according to circumstances.
The plates are generally used as negatives, the positive plates and the liquid
being constituted according to circumstances. Thus in the lead zinc accumulator
the positive plates are lead plates which may be made in any ordinary or suitable
way.
In using accumulator plates made according to this invention it is found
expedient to cover the plates with a wrapper or envelope of parchment paper or
equivalent material, held in place by rubber bands, or other suitable means the
presence of this protective covering rendering it possible to charge and discharge
the battery rapidly, without injuring the plates.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
1. The hereinbefore described process of making active material for secondary or
storage batteries by forming an alloy of lead and other metal, such as zinc,
disintegrating or reducing the alloy, eliminating the metal alloyed with the lead
and leaving the latter in a porous, distended condition, and compressing into the
desired form.
2. In a lead zinc secondary or storage battery a negative element consisting of
the combination with a frame, core or other suitable support, of an amalgam rich in
mercury, securely held therein.
3. The manufacture of electrodes for lead zinc secondary or storage batteries
by spreading over or introducing into the interstices or spaces between frames,
divisions, wire gauze, rods or supports of any suitable form, amalgams rich in
mercury, that is to say, composed of about equal proporations of mercury and of the
other metal employed.
Dated this 16th day of December 1892.
J. H. JOHNSON & Co.,
47, Lincoln's Inn Fields, W.C., Agents.