IMPROVEMENTS IN SECONDARY BATTERIES OR ACCUMULATORS
Year: 1884

page_text: I DESMOND GERALD FITZ GERALD of 6 Akerman Road, Brixton, in the County
of Surrey, Electrician, do hereby declare the nature of the said invention for
"IMPROVEMENTS IN SECONDARY BATTERIES OR ACCUMULATORS," to be as follows:-
The object of my Invention is to greatly diminish the time requisite to "form"
the plates in the Secondary battery of the "Planté" type and to allow of the
substitution in other forms of accumulator of a simple plate of lead in lieu of
anodes of more complicated structure. This Invention in fact allows of the
formation upon the surface of a plate of lead, even in a single operation of charging,
of a coherent layer of peroxide of lead sufficient in thickness to constitute this
plate an efficient element in a secondary battery.
My Invention consists in the employment, as the electrolyte in charging the
secondary battery, of a solution of sulphate of magnesia alone or in conjunction
with other salts. As the solution of sulphate of magnesia becomes acid by the
effect of electrolysis, I from time to time add magnesia or the carbonate of this
earth to the solution in order to neutralise the sulphuric acid liberated. This
charging solution may, when the secondary battery is discharged be replaced by
a solution of higher conductivity such as dilute sulphuric acid.
Thus in batteries of the Planté type I substitute for dilute sulphuric acid as the
electrolyte in charging the battery, a solution of sulphate of magnesia which may
be half saturated or of greater strength. By this means I obtain upon the anode
in the first operation of charging, a layer of peroxide of lead incomparably greater
in thickness than that which can be obtained in one such operation when dilute
sulphuric acid is used as the electrolyte. By subsequently reversing the current,
the peroxide of lead on this plate becomes reduced to metallic lead in a porous
condition whilst peroxide is formed upon the opposing plate. Thus the process of
forming" can be effected by one reversal of the current, i.e. by two operations of
charging, the second of which is in the direction opposite to the former instead
of by a lengthened series of such reversals with long intervals between them.
"
I construct also secondary batteries partly on the Planté and partly on the Fauro
type, in which, by the use of a solution of sulphate of magnesia as the electrolyte,
the process of" forming" the anode (in charging) which consists of a simple plato
of lead which may be roughened, corrugated, or perforated with small holes, may
be completed in one operation of charging. In this form of battery the cathode

page_text: (in charging) consists of a plate of lead, preferably roughened or perforated with
small holes coated or prepared with a layer of an oxide or insoluble salt of lead or
with a mixture consisting of equivalents of sulphate of lead and magnesia which is
readily reduced by the action of nascent hydrogen, or again, with a layer of lead
in a spongy or finely divided condition. Or instead of so coating the surface of
the cathode plate with a layer of such materials, the latter may be held or contained
within the small holes with which the plate may be perforated.
In the case of batteries constructed in the spiral form, I prefer to separate the
plates by means of a ribbed fabric of cotton, linen, woollen or asbestos, the direction
of the ribs being vertical so as to allow of the escape of any hydrogen or oxygen
gas that may be liberated in the process of charging.

page_text: "
I DESMOND GERALD FITZ GERALD of 6 Akerman Road, Brixton in the County
of Surrey, Electrician, do hereby declare the nature of the said invention for
"IMPROVEMENTS IN SECONDARY BATTERIES OR ACCUMULATORS 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 my Invention is to greatly diminish the time requisite to "form
the plates in the secondary battery of the "Planté" type and to allow of the
substitution in other forms of accumulator of a simple plate of lead in lieu of
anodes of more complicated structure; this Invention in fact allowing of the
formation upon the surface of a plate of lead, even in a single operation of charging,
of a coherent layer of peroxide of lead, sufficient in thickness to constitute this
plate an efficient negative element in a secondary battery.
"
My Invention consists in the employment as the electrolyte in "forming" and
charging" (or in "charging" only in the case where no "forming" is necessary)
the secondary battery of a solution consisting essentially of sulphate of magnesia,
or of an electrolyte containing this salt in sufficient proportion to produce the
effect desired.
As this solution becomes acid by the effect of electrolysis, I find it desirable
(when I do not intend to use the same electrolyte during the discharge of the
battery as hereafter mentioned) to add magnesia, or the carbonate of this earth, to
the solution during the process in order to neutralise the sulphuric acid liberated.
This charging solution may, when the secondary battery is to be discharged, be
replaced by a solution of higher conductivity such as dilute sulphuric acid; or the
Bolution of sulphate of magnesia which has become acid by the effect of electrolysis
(and which has not been neutralised as above mentioned) may be retained with or
without the addition of a further quantity of sulphuric acid.
"
Thus, in batteries of the Planté type, I substitute for dilute sulphuric acid as the
electrolyte in charging the battery, a solution of sulphate of magnesia which may
be half saturated (at 60° Fah :) or composed of one part by weight of the common
crystallised salt to about two parts of water, i.e. one part by weight of the
anhydrous salt to five parts of water. The specific gravity of this solution is
about 1-207, but I do not confine myself to the use of a solution of this particular
strength. By this means I obtain upon the anode in the first operation of
charging," a layer of peroxide of lead incomparably greater in thickness than
that which can be obtained in one such operation when dilute sulphuric acid is
used as the electrolyte. By subsequently reversing the current, the peroxide of
lead on this plate becomes reduced to metallic lead in a porous condition, whilst
peroxide is formed upon the opposing plate. Thus, the process of "forming" and
charging" can be effected by one reversal of the current, i.e. by two operations,
in the latter of which the passage of the current is in the opposite direction to the
former, instead of by a lengthened series of such reversals with long intervals
between them as is ordinarily requisite.
It is advisable, after charging the secondary couple in one direction, to "run
down" the couple before commencing to charge in the opposite direction, not only

page_text: in order to avoid obtaining a mixture of pride of lead and reduced lead upon
the surface of the plate which was made the anode in the initial operation of
charging, but also in order to obtain a more coherent layer of the reduced metal.
I construct, also secondary batteries of a composite character in which, by the
use of a solution (preferably a half saturated solution), of sulphate of magnesia as
the electrolyte, the process of "forming" and "charging" the elements may be
completed in one operation. In this case the anode (in charging) consists of a
simple plate of lead which may be roughened, corrugated, perforated, or pitted with
small holes, and the cathode (in charging) consists of a plate of lead (preferably
roughened or perforated with small holes) coated, or prepared with a layer of an
oxide or insoluble salt of lead, or with a mixture consisting of equivalents of
sulphate of lead and magnesia which is readily reduced by the action of nascent
hydrogen, or again with a layer of lead in a spongy or finely divided condition.
Or, instead of so coating the surface of the cathode plate with a layer of such
materials, the latter may be held or contained within the small holes with which
the plate may be perforated or pitted.
In the case of batteries constructed in the spiral form, I prefer to separate the
plates by means of a ribbed fabric of cotton, linen, woollen, or asbestos, the
direction of the ribs being vertical so as to allow of the escape of any hydrogen or
oxygen gas that may be liberated in the process of charging.
A solution of sulphate of magnesia which may be in admixture with another
salt such as the sulphate of zinc or the sulphate of soda-may also be advan-
tageously employed as the electrolyte in charging batteries other than those
hereinbefore referred to, that is to say in batteries wherein a lead anodo is
employed in conjunction with a cathode of another metal.
Having now particularly described and ascertained the nature of the said
Invention and in what manner the same is to be performed, I declare that what
I claim is
1st In the construction, or preparation, of a secondary battery of the Planté type,
the combination with anodes and cathodes of lead of an electrolyte consisting of
sulphate of magnesia in solution, or of an electrolyte containing this salt in
sufficient quantity to enable the process of "forming" and "charging" to bo
effected by two passages of the current in opposite directions.
2nd In the construction, or preparation, of a secondary battery, the combination
with a lead anode and with a cathode of lead coated, prepared with, or supporting
an oxide or insoluble salt of lead, or a mixture of sulphate of lead and magnesia, or
lead in a spongy or divided condition, of an electrolyte consisting of sulphate of
magnesia in solution or of an electrolyte containing this salt in sufficient quantity
to enable the process of charging to be effected with one passage of the current.
3rd In the preparation of a secondary battery, the herein described process of
producing upon a lead anode a layer or deposit of peroxide of lead of sufficient
thickness to act as an efficient negative element in discharging, by submitting said
anode (in conjunction with any suitable cathode) to electrolysis in a solution of
sulphate of magnesia, or in a solution containing this salt in sufficient proportion
to produce the desired effect, substantially as specified.
DESMOND G. FITZ GERALD.
By A. M. & W Clark, Patent Agents,
53, Chancery Lane, London.