IMPROVEMENTS IN VOLTAIC BATTERIES
Year: 1884

page_text: We, DESMOND GERALD FITZ-GERALD, of 6, Akerman Road, in the County of
Surrey, Electrician, and THOMAS JOHN JONES, of 12, Princes Street, Hanover
Square, in the County of Middlesex, Electrician, do hereby declare the nature of
the said invention for "IMPROVEMENTS IN VOLTAIC BATTERIES," and in what
manner the same is to be performed, to be particularly described and ascertained
in and by the following statement:-
The object of our Invention is to diminish the working cost and to increase the
efficiency of voltaic batteries to be employed in telegraphy, for actuating electric
bells and other apparatus, in telephony, for economically obtaining electric illumin-
ation more especially in private houses and on a comparatively small scale without
the inconvenient necessity for a gas or steam engine and a dynamo-machine as
part of the installation, for storing motive power within smaller bulk and weight
than have hitherto been praticable, and for other applications of the electric
agency.
This object we effect by constructing the positive and negative elements of the
battery, or the active portion of these elements, of materials which are capable of
generating a steady current under a high electro-motive force, and which are also
susceptible of being readily and economically regenerated or reconverted into their
original form by electro-chemical means after they have served for the production
of such current.
.
Hitherto, in primary batteries, zinc has been almost exclusively employed as the
positive element, being ordinarily converted into the sulphate of the metal. The
experience of many years has, however, shown that it is impossible economically
to recover the zinc in the metallic form from this salt, either by chemical or by
electro-chemical means. In lieu of zinc we employ as the positive element of our
battery, the metal lead which is readily reducible from most of its compounds,
either by chemical, metallurgical, or electro-chemical means. The active portion of
this (positive) element is lead in a more or less porous or spongy condition as
obtained by the compression of finely divided lead or by the electrolytic reduction
of the metal from one of its oxides or salts. The metal lead when in this porous
condition constitutes an excellent positive element for batteries, as, for instance, in
an electrolyte of dilute sulphuric acid which almost wholly converts it into sulphate
of lead when the circuit is closed without the production of any efflorescent salt

page_text: such as the sulphate of zinc which is so inconvenient and detrimental in voltaic
batteries wherein zinc is employed as the positive element. As the negative
clement we also employ lead coated by electrolysis with a coherent layer of the
peroxide of lead.
The essential feature of the present invention, however, consists in the conversion
of sulphate of lead into spongy lead to form the above mentioned positive elements,
and the further conversion of this spongy lead or of spongy load from another
source into peroxide, of lead for the production of negative elements, as will be
described.
The following are examples of the modes in which we construct the elements of
our battery.
Wo take a thin plate of lead preferably of the shape shown in Figure 1 of the
accompanying drawings, where A, B, C, D is the plate having at A and B two
tangs or projecting pieces which are soldered to a stout wire e, f, which may be of
copper varnished with sealing. wax or other varnish, and which is bent downwards
at one end for the purpose of bringing the plate into contact with mercury contained
in a grooved receptacle attached. outside the converting tank hereafter referred to,
and also the battery trough. This lead plate may, with advantage, be roughened
after the fashion of a nutmeg grater or be perforated with small holes, or it may be
amalgamated. Upon the clean surface of this plate is equally spread a layer of a
pasty mass composed of equivalents of sulphate of lead and magnesia (i,e. in the
proportions of one part by weight of magnesia to seven and a half parts by weight
of sulphate of lead) with water or of sulphate of lead made into à paste with an
alkaline solution. The plates which are intended to constitute the negative
elements of the battery should be coated with a layer of the paste of twice the
thickness of 'that upon the plates intended to constitute the positive elements of the
battery, and the tangs, as well as the supporting wire, are coated with an impervious
varnish as shown by the shaded portions A and B in Figure 2 of the drawings.
The sulphate of lead, above referred to, is usually the spent material which results
from the working of lead batteries. The mixture or pasty mass of sulphate of lead
should be applied to the plates before it has had time to set or harden. When the
composition has hardened upon the plates, these are subjected to electrolytic action
as cathodes in a trough or tank such as that shown in figure 3 of the drawings, in
which the electrolyte is sulphate of magnesia.
The corresponding anodes within such troughs, or a portion of such anodes
(eg anodes having one half the charging capacity of the whole of the anodes) may
be plates which have previously been treated as cathodes so as to obtain upon their
surface a layor of porous lead which is preferably subjected to compression and
allowed to become oxidised by exposure to the atmosphere. It will be seen that
if such plates, only, were employed as anodes in the tank, the result of the
operation would be the manufacture of negative or "peroxide" elements exclusively
This result is sometimes desirable as for instance when a number of "peroxide"
negative elements are required. for use with zinc positive elementa. But when
economy of working in the resulting battery is aimed at (the employment of zinc
as a positive element being in such case out of the question for reasons herein-
before adverted to) "reduced lead" positive elements equivalont in practice to the
peroxide negatives obtained should also be manufactured. In this case it is
necessary that a portion at least of the anodes omployed in the electrolytic or
charging tank should be derived from an outside source je, should be elements
that have not previously been employed as cathodes within the tank. Bearing in
mind the fact that the plates intended for negative elements in the battery should
preferably be of double substance, and that therefore, two plates suitable for positive
elements may be coated with porous lead in the operation of originally peroxidising
one negative element coated with oxide of lead derived from the oxidation of
spongy lead, it will be understood that the system generally most convenient in
practise is to employ anodes from an outside source to the extent of one half
the total charging capacity. We have found that when the electrolyte within the

page_text: charging tank is a solution of sulphate of magnesia such "anodes from an outside
source may be constituted by simple plates of lead which in this electrolyte
readily become coated with a layer of peroxide of lead of considerable thickness
and then constitute useful negative elements. But any other suitable lead anode
may be employed, either alone or in conjunction with the anodes hereinafter
specially described for obtaining spongy lead upon the cathodes prepared with the
mixture of sulphate of lead and magnesia.
When a number of the plates prepared with the pasty mixture of sulphate of
lead and magnesia, or of sulphate of lead and an alkaline solution, have been acted
upon electrolytically so as to convert the surface material into spongy metallic lead,
such of the plates as are intended to constituto positive elements in the battery,
are preserved in water until they are required for use and the remaining portion
of the plates which have been coated with porous lead may, after washing, be
exposed to the atmosphere until the porous lead on their surface has become
converted into oxide of lead. The plates so covered with a layer of oxide of lead
are to be used as anodes in conjunction with the cathodes coated with the pasty
mass or sulphate of lead mixture as above described. The electrolytic trough in
which this conversion is effected is furnished on each side with a grooved
receptacle a, a, and b,b containing mercury and connecting the anode and cathode
plates which are arranged alternately within the trough.
The anodes and the cathodes prepared as above in the electrolytic tank are, when
required for use, arranged in the battery trough as shown in figure 4, the negative
plates aa in one cell being maintained in contact with the positive plates b b in
the next cell by means of the mercury in the receptacles c c which are connected
together in couples by means of the wires ww. The negative elements in the
terminal cell P are, however, merely connected together by the mercury in the
terminal mercury receptacle c¹, this mercury being in contact with the binding
screw marked and constituting the positive pole of the battery. The positive
eleinents in the terminal cell N are similarly connected together and with the
binding screw marked - which constitutes the negative pole of the battery, by the
mercury in the receptacle c², or the plates may be connected by means of binding
screws as is well understood.
The electrolyte in the cells of the battery is preferably dilute sulphuric acid, the
strength of which may vary from one of acid to ten of water, to one of acid to only
five of water, by measure, according to the size of the cell and the quantity of
active material on the elements contained in it. The minimum weight of sulphuric
acid contained in each cell should be rather more than sufficient to convert into
sulphate the whole of the porous lead entering into the composition of the positive
elements within the cell, say one part by weight of the theoretical acid (H, SO₁)
to two parts of the porous lead. In the case of portable batteries however a much
lower proportion of acid may be made to suffice, but in such cases the electrolyte
should contain a salt, such as the sulphate of magnesia or the sulphate of an
alkali.
When the positive and negative elements in such a battery have become spent or
exhausted (ie. when the porous lead on the positive elements has become converted
into sulphate of lead, and the peroxide of lead on the negative elements has become
converted into an inert compound containing some peroxide with protoxide and
sulphate of lead) they are replaced by fresh elements and the spent material
(consisting mainly of sulphate of lead) is removed (by scraping and brushing)
from the old positive plates which may then be prepared as before with a mixture
of sulphate of lead (spent material) and magnesia in equivalent proportions. In a
similar manner the spent material may be removed from the surface of the negative
plates, and after treatment with a caustic alkali (or with magnesia) may again be
applied to the surface of such plates; or the exhausted negative plates may simply
be dipped in a solution of caustic alkali and be then reconverted into active
negative plates by treatment as anodes within the electrolytic trough.

page_text: The solution of sulphate of magnosis with which the electrolytic converting tank
is preferably charged, becomes strongly acid by use, and should from time to time
be neutralised by the addition of magnesia or its carbonate.
This process of preparing the elements for our battery differs essentially from the
method of working a secondary battery inasmugh na :—
(1). The elements after being conted respectively with reduced lead and peroxidé
of lead in an electrolytic trough or tank, are transported to a stationary battery
trough when required for uso.
(2). The charging or conversion is effected in an electrolyte (usually a solution of
sulphate of magnesia or an alkaline sulphate) other than that within the battery
trough in which the elements are discharged.
(3). The sulphate of lead formed upon our elements by the action upon them of
the sulphuric acid within the battery trough, is always converted (virtually or
actually) into oxide of lead by treating the spent material on the surface of the
plates with an alkaline solution or by removing such sulphate of lead from the
surface of the elements and mixing it with its equivalent of magnesia or with an
alkaline solution, such as that of caustic soda. By this means the difficult and
unsatisfactory process of electrolysing sulphate of lead is entirely avoided.
Having now particularly described and ascertained the nature of the mid
invention and in what manner the same is to bo performed we declare that what
we claim is
1st. The herein described method of manufacturing a positive element for a
primary voltaic battery, which consists in subjecting to electrolysis as a cathode
(in conjunction with any suitable anode) a mixture composed of sulphato of lead
and magnesia, or sulphate of lead and an alkali, applied in a plastic state to, or
formed on, the surface of a suitable conductor, whereby the sulphate of lead is
reduced to the state of an adherent layer of porous lead, substantially as specified.
2nd The herein described method of manufacturing a negative element for a
primary voltaic battery, which consists in first subjecting to electrolysis as a
cathode (in conjunction with any suitable anode) a mixture composed of sulphate
of lead and magnesia, or sulphate of lead and an alkali, applied in a plastic state to,
or formed on, the surface of a suitable conductor; then exposing the porous lead
thereby produced to the atmosphere for the purpose of oxidation; and finally
converting the layer of porous lead into peroxide of lead by electrolysis, sub-
stantially as specified.
3rd The production of elements for primary voltaic batteries by subjecting anode
plates of lead and cathode plates of lead, coated with a mixture of sulphate of lend
and an equivalent of magnesia or of sulphate of lead with an alkali, to electrolytic
action in a solution of sulphate of magnesia, substantially as specified.
4th The production of a negative element for a primary voltaic battery by
subjecting a plate of lead to electrolytic action as an anode in a solution of sulphate
of magnesia alone or in admixture with other salts in conjunction with any suitable
cathode substantially as specified.