IMPROVEMENTS IN VOLTAIC BATTERIES
Year: 1884

page_text: We DESMOND GERALD FITZGERALD of 6 Akerman Road, Brixton, 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:-
Our Invention consists in a method of manufacturing negative elements for
primary voltaic batteries, applicable also as negative elements (anodes in charging)
for secondary batteries.
According to this method, peroxide of lead is generated electrolytically from
oxide of lead (or compounds containing or convertible into an oxide of lead) in
such a manner as to produce dense, coherent and conductive plates wholly or
almost wholly constituted of the peroxide, to be used as negative elements in voltaic
batteries without contact with any oxidisable support. Such plates or elements
may be used with or (if of comparatively small dimensions) without a support
of non-conducting material.
In carrying out our Invention we obtain plates, slabs, or other forms of oxide of
lead from a pasty mass containing this substance (which may advantageously be
in admixture with finely divided lead which subsequently becomes oxidised) and
these plates, &c, when dry and hard we convert into dense, conductive, peroxide
of lead by means of electrolysis. We usually enclose and compress the pasty
mass of oxide of lead (or other compound convertible into peroxide of lead)
together with a conducting plate, tang, strip or wire which serves to effect the
electrolytic conversion of the oxide of lead, between plates or slabs of non-conducting
material such as porous earthenware, plaster of Paris, wood or ebonite which
virtually constitute, or may take the form of, a mould. When, as in the last
instance, the nonconducting material is also non-porous, one at least of the plates
between which the lead compound is enclosed must be perforated with holes or
apertures in order to allow of the electrolytic action whereby the lead oxide is
converted into lead peroxide.
This conversion is effected by means of an electric current from a dynamo-
machine or other suitable source of electricity, and of an electrolyte (preferably
a solution of sulphate of magnesia) in which the mould and its contained conductor
and material to be converted into lead peroxide constitute the anode, opposed to
any suitable cathode such as a plate of lead covered with oxide of lead. When
the conversion into lead peroxide of the material within the mould is complete, the
nonconducting plates or slabs (or one of them only) may be removed and the con-
ducting plate or strip when of non-oxidisable material, such as platinum, inay also
be removed (excepting in the case when it is embedded in the substance of the
plate of peroxide and is intended to serve as a permanent contact piece) and the
lead peroxide is left in the form of a plate which, if the operation has been properly

page_text: carried out, is sufficiently dense and coherent (at least in the case of plates
of moderate dimensions) even when both of the nonconducting plates have
been removed, to bear handling, and sufficiently conductive to serve as a voltaic
element. Contact with the plate of peroxide is preferably established, in the case
of elements for primary batteries, by means of a thin strip of platinum (wrapped
over a portion of the upper edge of the plate) and a suitable clamping screw.
But, in the case of elements for secondary batteries, the original non-oxidisable
strip, tang, or wire embedded in the peroxide and utilised for the conversion should
be retained to constitute a permanent contact piece when the element is in use.
When, however, a conducting plate of oxidisable material such for instance as a
plate of lead (which may advantageously be very thin or in the form of foil) is
employed for the electrolytic conversion of oxide into peroxide of lead, this plate
should be completely oxidised by the electrolytic action. In this, as in the former
case, consequently, the resulting plate (or plates) of lead peroxide may be employed
as the negative element of a voltaic couple without being liable to the deterioration
arising from "local action" which takes place when the peroxide is in contact with
an oxidisable support. The "plates" above mentioned may be either flat or of any
other suitable form. In some cases one of the plates or slabs of nonconducting
material may be dispensed with.
The nonconducting plate when the same constitutes a support for the plate of
peroxide of lead (as would be the case especially in large elements) is generally
perforated with holes or apertures, even when a porous plate is used, into which
the oxide or composition (in the form of a paste) to be converted into peroxide is
initially forced by pressure.
The compound we prefer to use for conversion into dense and conductive plates
of lead peroxide is a mixture of oxide of lead (litharge) with lead in a state of fine
division (in about the proportion of one by weight of the latter to two or three by
weight of the former) made into a paste with water or a dilute solution of sulphate
of magnesia. After being applied to the conducting plate and subjected to com-
pression, this composition is allowed to dry for several days (during which period
the finely divided lead becomes oxidised and the composition becomes extremely
dense and hard) and it is then subjected to the electrolytic action which results in
the production of a dense and conductive peroxide of lead.
A slab or plate of dense oxide of lead (obtained by moulding a pasty mass
preferably composed of oxide of lead (litharge) in admixture with finely divided
lend) may even be simply maintained in contact with an anode within an electro-
Jytic tank and be thus converted into a slab or plate of conductive peroxide of lead
suitable for use as a negative element in a voltaic battery, whether primary or
secondary, without maintaining the plate of oxide of lead between two surfaces
during the process of conversion, as previously described.
The following are examples of the manner of carrying out our Invention:-
We take a thin plate A (see the accompanying drawings, figure 1) of ebonite
(or porous earthenware) and place upon it a thin plate B of platinum preferably
perforated (or lead) of about the same dimensions as A, obtaining contact with
the latter by means of the binding screw S. We then coat plate B (all but a
portion of this plate near the upper edge) with a mixture or composition C of
oxide of lead (litharge) and finely divided lead (preferably in the proportions above
mentioned) made into a paste with water or a dilute solution of sulphate of
magnesia. A second plate D of ebonite or other non-porous, nonconducting
material perforated with through holes or apertures (or of porous earthenware
perforated or unperforated) is superposed upon the layer C and pressure is applied,
a sheet of felt or other suitable material being laid upon the plate D when the
latter is perforated for the purpose of absorbing moisture. This plate D may
advantageously take the form of a shallow tray with edges bevelled inside. The
plates A and D constitute in effect and may take the form of a mould. When
the plate D is constructed with holes or apertures, these should become wholly
filled by the effect of the pressure with the pasty composition. Bands of india-

page_text: rubber may be placed round the plates to prevent them from coming apart during
the conversion of the oxide of lead. The composition is allowed several days to
become dry, and in the process of drying, the finely divided lead becomes oxidised,
whilst the composition itself becomes very dense and hard. The mould, with its
enclosed lead composition and conductor, is then placed in a converting tank in
which the conductor constitutes an anode conveying a current from a dynamo
machine or other source of electricity through the composition and through an
electrolyte which is preferably a solution of sulphate of magnesia; any suitable
negative electrode (such as a plate of lead coated with lead oxide) being employed
to complete the circuit. It is not absolutely necessary to employ a plate of platinum
for effecting the conversion of the lead compound and in figures 1a and 1b we have
shown the platinum in the form of a curved strip or wire which may be used in
lieu of the plate B.
When the composition (together with the conducting plate, when this is of lead)
is converted into peroxide of lead, the plate A is removed. The conducting plate B
(if of platinum) may also be removed, and the plate C which has become converted
into peroxide of lead, may then be utilised as the negative element of a voltaic
couple, either in conjunction with D (which being in this case perforated serves
to strengthen and support the element) as shown in figure 2, or without this
supporting plate, as shown in figure 3. In either case a strip of platinum (Pt) may
be interposed between the peroxide and the clamping device S, or contact may be
obtained by means of a tang, strip or wire of platinum which has originally been
embedded in the composition and which may have been utilised in lieu of the plate
of platinum B to effect the complete conversion (though more slowly) of the whole
plate of dense oxide of lead into peroxide. This is shown in figure 1 in which C is
the peroxide and B a wire of platinum substantially of the form shown in figure 1b
embedded in the material.
The process admits of being varied in several ways, the essential point being the
electrolytic production of lead peroxide under conditions which ensure a high
degree of density and coherence. One of these alternative processes is illustrated
in figure 4 where B is the conducting plate of platinum (or lead) C C layers of any
suitable compound or paste containing oxide of lead, such as the composition
mentioned above in which the conducting plate B is embedded, and D D perforated
plates of ebonite (or plates of porous earthenware, either perforated or unper-
forated.) Two plates of conductive lead per-oxide, either with or without the
nonconducting supporting plates DD may be obtained by this method and the
whole may constitute a single element, or the plates of converted material may be
separated at the central plane parallel to the two faces of the plates so as to form
two elements, as will be readily understood.
Another alternative process consists in producing plates of dense oxide of lead
(by moulding or otherwise) and, after allowing such plates to become dry and
hard, effecting the conversion by simply maintaining them in contact with a
suitable anode surface within an electrolytic tank. Such anode surface may for
instance be of platinum, or lead previously peroxidised by the passage of the
current, and when this anode surface is horizontal or inclined, the plate of prepared
oxide of lead may be merely laid upon or against such anode surface until the
conversion is completed. When, however, the anode surface is vertical, suitable
means must be employed for holding the slab or block of prepared oxide of lead
in contact with the anode surface. By this modification elements may be obtained
without any supporting plates and without confining the oxide of lead between
two surfaces during the process of conversion. But we may have a single sup-
porting plate as in figure 5 where D represents a perforated plate of ebonite or
porous material, and C the composition of oxide of lead or other suitable lead
compound which, by pressure, has been forced into the perforations in D. Contact
with the anode surface, for effecting the conversion, may be made on either side of
the compound plate. Or again, we may coat both sides of a perforated or porous
noncordue ing plate or support with the composition, at the same time filling up

page_text: the apertures or pores in the support (as seen in Figure 6) and convert the com-
position as before; or this support may be merely roughened or grooved instead
of being perforated or made of porous material so as to cause the composition to
adhere. In this manner we obtain an element which is materially strengthened
by a nonconducting support.
Having now particularly described and ascertained the nature of the said
Invention and in what manner the same is to be performed, we declare that what
we claim is
1st The production of negative elements for voltaic batteries of dense, conductive,
peroxide of lead, by first preparing plates or masses of oxide of lead from a pasty
composition containing this material (preferably in admixture with finely divided
lead which becomes subsequently oxidised) then drying such plates or masses of
oxide of lead (under pressure when this is necessary to obtain the required density,
as in the case when metallic lead is not added to the oxide) and subsequently
converting the oxide of lead into peroxide of lead by maintaining the plates or
masses in contact with a suitable anode surface within an electrolytic cell or tank,
substantially as specified.
2nd The production of plates or masses of conductive peroxide of lead, to be
used as negative elements in voltaic batteries without contact with any oxidisable
support, by acting electrolytically upon a dense composition of oxide of lead, or
other suitable compound containing lead, whilst such compound is confined between
two plates or in a mould of porous material, substantially as described.
3rd The production of plates or masses of conductive peroxide of lead, to be
used as negative elements in voltaic batteries without contact with any oxidisable
support, by acting electrolytically upon a dense composition of oxide of lead, or
other suitable compound containing lead, whilst such material is confined between
two plates or in a mould of non-porous, nonconducting material, one at least of
such plates, or of the two portions constituting the mould, being perforated,
substantially as described.
4th The manufacture of negative elements for voltaic batteries from a paste
composed of oxide of lead, finely divided lead and water or any suitable solution,
substantially as specified.
5th The process of converting plates of dense oxide of lead to be employed as
negative elements in voltaic batteries into peroxide of this metal by means of elec-
trolysis in a solution of sulphate of magnesia, substantially as specified.
6th In the construction of negative elements for voltaic batteries, the combination
of a perforated or apertured support of nonconducting material and of a pasty mass
susceptible of being converted into peroxide of lead by electrolysis, which mass is
filled into the apertures and thereby held against the surface or surfaces of the said
support, substantially as specified.
7th The process of constructing the negative-elements of voltaic batteries by
causing a suitable lead compound in the form of a pasty mass to adhere to a
nonconducting perforated or porous, support, or a support having a grooved or
irregular surface, drying the pasty mass, and then converting the same into
peroxide of lead by electrolysis, substantially as specified.
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