IMPROVEMENTS IN SECONDARY BATTERIES OR ACCUMULATORS .
Year: 1883

page_text: LETTERS PATENT to Desmond Gerald Fitz-Gerald of Brixton in the county
of Surrey Electrician for an Invention of IMPROVEMENTS IN SECONDARY
BATTERIES OR ACCUMULATORS
.
PROVISIONAL SPECIFICATION left by the said Desmond. Gerald Fitz-Gerald
at the Office of the Commissioners of Patents on the 1st March 1883.
DESMOND GERALD FITZ-GERALD of Brixton in the County of Surrey
Electrician "IMPROVEMENTS IN SECONDARY BATTERIES OR ACCUMULATORS"
This Invention relates to improvements in secondary batteries or accumulators.
In secondary batteries with lead electrodes as hitherto constructed, the anode
plate becomes rapidly disintegrated by reason of "local action" set up between the
metal and the coat of lead-peroxide; these being in contact with each other and
with the electrolyte.
Now my Invention consists in the manufacture of indestructible electrodes, or of
electrodes which will last for an indefinite period, by the use of any suitable
impervious and insulating materials with which the electrode or the supporting
plate backing is in part coated, prepared or saturated.
Or if the electrode or supporting plate be porous the whole of it, instead of a
portion only, may be saturated with a the impervious material, which however is
partly or wholly removed from the surface of the electrode so as to allow of good
contact between it and an electrolytic fluid. It will be understood that the object
of so coating, saturating or preparing the electrode or supporting plate is to prevent
its total disintegration, more especially in the case of the anode or positive
electrode, generally by preserving a frame or network of unaltered material which
can only be attacked by the fluid in the direction of the plane of the plate, instead
of at every point of the surface as hitherto has been the case. Any appreciable
augmentation of the resistance of the cell may be obviated by covering the partly
coated or the prepared or saturated plate with a layer of materials to be converted
into peroxide of lead.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
46
by the said Desmond Gerald Fitz-Gerald in the Great Seal Patent Office on
the 1st September 1883.
DESMOND GERALD FITZ-GERALD of Brixton in the County of Surrey, Electrician
IMPROVEMENTS IN SECONDARY BATTERIES OR ACCUMULATORS."
This Invention relates to improvements in secondary batteries or Accumulators.
In secondary batteries with lead electrodes as hitherto constructed, the plate
constituting the anode in charging becomes more or less rapidly disintegrated by
reason of local action set up between the metal and the lead peroxide produced,
these being in contact with each other and with the electrolyte.
Now my Invention consists in the manufacture of "indestructible electrodes "
(that is to say, of electrodes which will last for an indefinite or comparatively
lengthened period) by the use of any suitable impervious and insulating material
with which the electrode is in part coated or protected. The object of so coating
or protecting an electrode is to prevent its total disintegration, more especially in
the case of the anode or positive electrode (in charging) by preserving certain
portions of unaltered metal which can be attacked by the electrolyte only in the
direction of the plane of the plate instead of at every point of the surface of the
plate as hitherto has been the case. With this construction the internal
resistance of the battery is not materially augmented if the protection be
confined to the anode.
The impervious and insulating materials I prefer to make use of are either of
the substances known in commerce respectively as Prouts' Glue, Charakite, and
Jeffreys Marine Glue. The first named material gives the best result, but inixtures
of two or more of the following substances, viz-Caoutchouc, Shellac, Resin,
Asphalte, Paraffine-wax, Bees-wax, Pitch, Asbestos (in powder) may be found
suitable.
My indestructible electrodes may be made in either of the following forms or
ways, but it must be understood that I do not limit myself to these particular
modes of construction:-
(1) I take a sheet of lead a (see the accompanying sheet of drawings-Figure 1)
punctured over both surfaces (or one surface only in the case of terminal plates)
by means of needle points as set forth in the specification of former Letters Patent
dated 6th December 1881 N° 5338 whereby the surface and consequently the
charging capacity of the plate are increased. I then protect certain portions of
the surface by the application of a network 6 of the impervious material, formed
by rolling it into sheets of suitable thickness and then making through openings
of any suitable shape in the sheets by punching out or otherwise removing the
material so as to leave it in the form of a regular open network or framework
which is then applied to the lead plate whilst the latter is sufficiently hot to cause
the material to adhere firmly thereto. When both surfaces of the lead plate are
to be protected, it is desirable that the apertures of the insulating coverings should
coincide with one another so as to ensure the preservation of a network or
honey-comb-like structure of lead unaltered throughout its thickness. Instead of
applying the impervious material in the above form, it may be applied in the form
of strips which may be crossed or interlaced, or preferably arranged in parallel
strips with intermediate distance pieces or cross bars fitting between the longi-
tudinal strips and united thereto by the heat which at same time causes-them to
adhere to the plate. I do not however limit myself to the precise methods of
applying the impervious material, as others might also be adopted.

page_text: (2) I enclose in a perforated receptacle constructed as hereafter described, porous
or spongy lead which may be obtained by chemical precipitation, as for instance
from the acetate by means of zinc or by electro-deposition as in the cathode
compartment of the electrolytic tank referred in the specifiation [sic] of a Patent of
even date herewith granted to myself and T. J. Jones, N° 1121, or mechanically.
The envelope or casing is formed of a sheet of lead a or any suitable alloy of this
metal perforated with small holes placed so close together that at least 50% of
the material is removed by the perforation. This perforated sheet is protected on
both sides by a network of impervious material 6 applied as above described and
shown in Figure (care being taken that the apertures in the two protecting
sheets coincide.) This protected perforated sheet having been bent double as shown
in cross section in Figure 2 and the Spongy lead having been placed between as
shown at c. the edges of the envelope are bent inwards and the whole is subjected
to sufficiently powerful pressure in a suitable mould to make the spongy lead and
envelope form a coherent plate. The edges of the compound plate may be
enclosed by strips of the impervious material applied after the plate is compressed.
I obtain contact with the element by means of this perforated casing alone, or
in conjunction with a central conducting plate d either of lead or of a suitable
alloy of this metal. I cover or enclose this central conducting plate on both sides
with a perforated, reticulated, or open work sheet of the preservative insulating
material b¹ as in the case of the electrode previously described.
A modification of the last described method of construction is to extend the
central protected plate d to the whole depth and width of the electrode and to
dispense with the perforated metallic envelope a the external insulating material b
alone serving to prevent disintegration of the porous material. In this mode of
construction very powerful pressure should be applied to consolidate the plate prior
to the application of the protective covering b which is then caused to adhere by
the aid of heat as first above described.
Having described the nature of my Invention and the manner of performing the
same, I would have it understood that I do not limit myself to the methods of
producing the electrodes above described as these are given by way of example
only, but that what I claim as my Invention to be protected by the hereinbefore
in part recited Letters Patent is :
In Secondary batteries or Accumulators, the employment in combination with
the electrodes and more particularly the anode, of a partial covering of impervious
and insulating material applied in such a form and way as to protect portions of the
electrode from the action of the electrolyte and leave a continuous network or
framework of unaltered metal, substantially as specified.
In witness whereof I the said Desmond Gerald Fitz-Gerald have hereunto
set my hand and seal this thirty first day of August A.D. 1883.
T. W. KENNARD
Clerk to
A. M. &. W. Clark
53 Chancery Lane
Patent Agents,
DESMOND, G. FITZ-GERALD. (LS.)