IMPROVEMENTS IN SECONDARY OR STORAGE BATTERIES
Year: 1882

page_text: LETTERS PATENT to Desmond Gerald Fitz-Gerald of Brixton in the county
of Surrey Electrician and Thomas John Jones of Princes Street Hanover
Square in the County of Middlesex Electrician for an Invention of "IMPROVE-
PROVISIONAL SPECIFICATION left by the said Desmond Gerald Fitz-Gerald
and Thomas John Jones at the Office of the Commissioners of Patents on the
1st September 1882.
DESMOND GERALD FITZ GERALD of Brixton in the County of Surrey Electrician.
and THOMAS JOHN JONES of Princes Street Hanover Square in the County of
Middlesex Electrician IMPROVEMENTS IN SECONDARY OR STORAGE BATTERIES
"
This invention relates to improvements in secondary or storage batteries and
consists mainly in a practically efficacious method of utilising Carbon generally in
the form of rods, plates or hollow cylinders of Gas carbon surrounded with or
surrounding a mixture of fragments of the same material and metallic lead or an
oxide or insoluble salt of this metal, in the construction of secondary or storage
batteries. We have ascertained by repeated experimental trial, that carbon when
employed as a positive electrode or anode, becomes oxidised and corroded, that it
does not allow of the conversion of lead or its oxide into the peroxide, and that
therefore no secondary battery with a carbon anode can give practically useful
results. On the other hand we have ascertained that carbon in the form above
mentioned when employed as a negative electrode or cathode, in contact with oxide
of lead or an insoluble salt of this metal becomes "polarised" by hydrogen and
coated with lead in such manner as to become an unusually effective positive
element in a couple having lead in contact with peroxide of lead for the negative
element. Now whenever the use of carbon as an electrode in secondary batteries
has been specified, mentioned or claimed, no limitation of it to the construction of
the electrode constituting the cathode when the battery is being charged has

page_text: hitherto been made, with the result that secondary batteries with carbon electrodes
have necessarily resulted in failure. But according to our invention carbon, in
contact with lead or with an oxide or insoluble salt of lead is employed only in
the construction of the electrode which is to constitute the cathode in charging, or
the anode in discharging, the secondary couple or battery. For the electrode which
constitutes the anode in charging, we prefer to use a plate of lead to which a coating
of considerable thickness of lead amalgam has been applied any excess of mercury
being removed from the amalgam by pressure or by simply allowing such excess to
drain away. The electrolyte usually employed viz: dilute sulphuric acid may be
used in conjunction with these electrodes

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Desmond Gerald Fitz-Gerald and Thomas John Jones in the Great
Seal Patent Office on the 1st March 1883.
DESMOND GERALD FITZ-GERALD of Brixton in the County of Surrey, Electrician,
and THOMAS JOHN JONES of Princes Street, Hanover Square in the County of
Middlesex, Electrician IMPROVEMENTS IN SECONDARY OR STORAGE BATTERIES
In constructing secondary batteries according to our Invention we employ
carbon in conjunction with finely divided lead or an oxide or insoluble salt of this
metal as the electrode which is to constitute the cathode in charging (or strictly
speaking the support for the reduced metal which becomes the cathode) and the
anode in discharging the secondary battery. The limitation of the use of carbon
to this electrode is the main point of novelty and utility in the present invention
which has no reference to secondary batteries constructed with carbon as the
material mainly entering into the composition of both electrodes, in accordance
with the methods which have hitherto been suggested for utilising carbon in
secondary batteries; which methods. we have found by experimental trials
extending over a considerable period of time to be ineffective and impracticable.
For the electrode which is to constitute the anode in charging or the cathode in
discharging the battery, we preferably employ metallic lead in conjunction with
the same metal in a finely divided (but non-compressed) condition, or with an
oxide or insoluble salt, of this metal (and more particularly the "indestructible"
anode for which application for provisional protection has been made by one of the
present inventors dated the first day of March A.D. 1883) but although we herein-
after specify certain electrodes which we have found to be effective as anodes
(in charging) when employed in conjunction with our carbon cathodes, we would
have it understood that we do not limit ourselves to or claim as novel the anodes
thus specified; but that we use carbon as the cathode (in charging) in conjunction
with any suitable anode.
We will now proceed particularly to describe and specify the modes in which
according to our invention carbon is employed in the construction of the electrode
which is to constitute the cathode (when charging) of our secondary batteries.
We take rods or plates of gas carbon or of any other kind of carbon which does
not readily become disintegrated and on one extremity or edge of such rods or
plates we cast a cap or contact piece of lead or any suitable alloy in which may be
imbedded a wire or strip of metal and we preserve such contact piece from
corrosion preferably by means of paraffin-wax with which the carbon in proximity
to such contact piece is saturated, as is well understood. The rods or plates of
carbon if sufficiently porous, may be impregnated with metallic lead or with an
oxide or an insoluble salt of lead by immersing the carbon in a solution of a soluble
salt of lead and after drying, heating the carbon to low redness with or without
access of air or treating it with any reagent (such as an alkaline solution or dilute
sulphuric acid, or an alkaline sulphate tartrate or phosphate) which will decompose
the soluble salt of lead and precipitate oxide or an insoluble salt of lead within the
pores of the carbon; the process being repeated until a sufficient degree of
impregnation has been obtained. In this case the carbon electrodes so treated
(more especially if they be grooved, recessed or perforated) may be employed alone
as the cathode in charging but we prefer to surround the rods or plates of carbon,
so impregnated or otherwise, with fragments of carbon which also may be
impregnated with metallic lead or with an oxide or insoluble salt of lead in the
manner just described or by electro-deposition. The carbon fragments which are

page_text: to surround the rods or plates of carbon are in any case coated either with metallic
lead preferably by electro-deposition or with an oxide of lead (litharge or red-lead)
or with an insoluble salt of lead, preferably by moistening the fragments with
water or with very dilute sulphuric acid and agitating them in contact with the
oxide or insoluble salt of lead. And when the carbon fragments are placed in
position around the central carbon.conductors the interstices between them may be
wholly or in part filled up with the oxide or insoluble salt of lead. To maintain
the carbon fragments in contact with the carbon conductors, a casing or diaphragm
of felt or other porous material may be employed; but we prefer to use a perforated
plate or receptacle of carbon, lead or other substance, either conducting or non-
conducting, which is not detrimentally acted upon by dilute sulphuric acid or other
fluid constituting the electrolyte. We have found a rectangular casing or
receptacle formed of perforated sheet lead to answer very effectively the purpose
of maintaining the carbon fragments, prepared and coated as described, in contact
with the carbon plates or rods. The prepared carbon fragments should be tightly
rammed in this receptacle the latter being placed within a mould for the purpose.
In constructing such receptacles, the edges of the perforated sheet may be fastened
together by means of a folded joint or by autogenic soldering.
The perforations in the sheet lead or other material (conducting or non-
conducting) of which the receptacle is constructed may be of any size such as will
not allow of the passage of the smallest of the carbon fragments employed; but we
have found sheet lead inch in thickness, with perforations 065 in diameter of
which there are 120 to the square inch to answer the required purpose effectively.
When the perforated receptacle is of sheet lead, carbon or other conducting
material, we sometimes dispense with the central plate or rods of carbon, and
employ the receptacle itself as the means of obtaining contact with the carbon
fragments. The diaphragm, casing or receptacle necessary to maintain the carbon
fragments in position may take the form of a network of any metallic wire not
detrimentally acted upon by the electrolyte, or of any suitable non-conducting
material such as gutta percha or vulcanite. We prefer to construct these electrodes
of a flat rectangular form, but they may be made of cylindrical shape; the pre-
pared carbon fragments being in that case contained within a perforated cylinder of
carbon, lead or non-conducting material. The central carbon conductor is in the
latter case essential. We sometimes construct compound electrodes, one surface of
which becomes an anode and the other a cathode in charging, such plates being
used to divide a trough into cells as is well understood. In this case we usually
dispense with the carbon fragments, and impregnate with lead or with an oxide or
insoluble salt of lead (as hereinbefore described) a plate of porous carbon of which
one surface is preferably grooved or recessed. To the other surface is cemented by
means of marine glue or other waterproof and insulating cement, a plate of lead,
brought into good conductive contact with the carbon at a point in what is
intended to be the upper edge of the compound plate. Such plate of lead which
may be coated with lead-amalgam, or with finely divided lead, or with an oxide or
insoluble salt of lead maintained by suitable means in contact with the metal,
constitutes the anode surface of the compound plate in charging; the prepared
carbon being always the cathode surface in charging,
As the anode (in charging) used in conjunction with our carbon cathode, we have
employed a plate of lead coated with lead amalgam. But in this case in order to
obviate the effects of disintegration or scaling it is expedient to use a porous
diaphragm of felt or similar material which is objectionable not only from its want
of durability but because it adds to the resistance of the battery and sometimes
occasions the short circuiting of a cell. This applies also to anodes formed by
maintaining an oxide of lead in contact with a plate of this metal. For this reason
we prefer to use an anode consisting of a rectangular receptacle of perforated lead
similar to that employed for holding in position the prepared carbon fragments
in the cathode element, but of considerably less capacity although ordinarily of the
same height and width and with somewhat smaller perforations the lead of which

page_text: it is made being however thicker, say for instance 1/16 inch. This receptacle is filled
with lead in a condition of minute subdivision or with the crystalline lead obtained
by reducing lead from a soluble salt of the metal such as the acetate, by means of
zinc. Contact with this loosely coherent lead is obtained by means of the lead
receptacle. Or, in this case again the minutely subdivided or crystalline lead may
be contained in a perforated receptacle of any suitable non-conducting material
such as gutta percha or vulcanite the contact being established by means of a plate
of lead surrounded with the loosely coherent metal. Theoretically, the weight of
the minutely subdivided lead entering into the composition of the anode should be
less (in about the proportion of 100 to 108) than the weight of oxide of lead sur-
rounding the carbon fragments; but as the conversion of the former into peroxide
of lead is not so complete as the reduction of the latter into metallic lead, and as
hydrogen as well as lead is reduced at the cathode, there is no disadvantage in
using equal weights of the finely divided lead and oxide of lead respectively at the
anode and cathode in charging. When a secondary battery, so constructed with
metallic lead at the anode and an oxide of lead at the cathode (in charging), is first
mounted, it is advantageous to short circuit it before proceeding to charge it, the
result being the formation of some oxide of lead at the anode and some reduced
lead at the cathode. If this be not done, a quantity of electricity double that
which is requisite in subsequent chargings is at first requisite in order to convert
the metallic lead at the anode into peroxide of lead. This double quantity of
electricity which is required to traverse each cell is 234 ampère hours for every
pound avoirdupois of finely divided lead used in constructing the anode of the cell.
In subsequent chargings, half this quantity, or 117 ampère hours, is required for
every pound of active lead at the anode surface.
Having described the nature of our said Invention and the manner of performing
the same, we declare that what we claim as our Invention to be protected by the
herein before in part recited Letters Patent is:-
The construction and use of secondary batteries having the electrode which
constitutes the cathode in charging the battery made of carbon in conjunction with
finely divided lead or an oxide or insoluble salt of this metal and having the other
electrode made of a substance other than carbon, substantially as specified.
In witness whereof we the said Desmond Gerald Fitz-Gerald and Thomas
John Jones, have hereunto set our hands and seals, this first day of March,
in the year of our Lord, one thousand eight hundred and eighty-three.