IMPROVEMENTS IN SECONDARY BATTERIES AND IN THE PROVISIONAL SPECIFICATION
Year: 1882

page_text: LETTERS PATENT to John Evelyn Liardet of Brockley in the County of
Kent and Thomas Donnithorne of Gracechurch Street in the City of London
LETTERS PATENT to John Evelyn Liardet of Brockley in the County of
Kent and Thomas Donnithorne of Gracechurch Street in the City of London
for an Invention of "IMPROVEMENTS IN SECONDARY BATTERIES AND IN THE
PROVISIONAL SPECIFICATION left by the said John Evelyn Liardet and
Thomas Donnithorne at the Office of the Commissioners of Patents on the
19th October 1882.
JOHN EVELYN LIARDET of Brockley in the County of Kent and THOMAS
DONNITHORNE of Gracechurch Street in the City of London "IMPROVEMENTS IN
SECONDARY BATTERIES AND IN THE MANUFACTURE OF THE SAME
"
This Invention has for its object improvements in secondary batteries and in the
manufacture of the same for storing electrical energy and consists in part of
improvements on and additions to the Invention described in the Specification of
the Patent applied for by us on the 9th January 1882 Ñº 120.
We prefer to construct the electrodes of the elements of which the secondary
battery is composed of very thin sheets of pure metallic lead-i.e. instead of using
the thick leaden plates which are customary in secondary batteries we prefer to
use the thinnest pure metallic lead which we can obtain taking such mechanical
precautions as may be necessary to support its weight when it is coated with the
salts of lead whether mixed or not with finely divided metallic lead.
We will afterwards describe the manufacture of the salts of lead.
In some cases we may use carbon plates as the electrodes but in those cases we
prefer to use thin plates of dense carbon and charge the pores of this carbon with
the salt of lead afterwards reducing it as far as practicable to a metallic state by
electrolitic action so as to increase the conductivity of the carbon.
To prepare the secondary battery we put a coating of suitable salts of lead
preferably prepared as hereinafter described upon the surface of this leaden or carbon
electrode. We prefer to retain this coating in place either by putting the
electrode inside a porous cell similar in character to the porous cells in use in

page_text: Grove's and other batteries but constructed so as to have the greatest practical
amount of porosity when combined with sufficient strength to retain the lead salts
and constructed of material which possesses low resisting power.
In some cases we prefer to use porous plates constructed in a similar way which
plates are adapted to and securely fixed in grooves or otherwise in cells or troughs
of vulcanite earthenware slate wood lined with non conducting material or other
suitable substance so as to form. cells in which the elements may be immersed.
One side of each of these cells i.e. the sides of the elements which are opposed to
each other will be constructed of porous slabs or plates while the other sides in
which tho elements are not opposed to each other will be constructed of impervious
non-conducting materials.
In other cases we prefer to construct the elements in a series of circular porous
pots nested one inside the other the spaces between the circular porous pots forming
alternately the elements of the secondary battery and the spaces between the
separate elements to contain the dilute sulphuric acid or other exciting fluid used.
Having thus constructed the cells and the electrodes we construct the elements
of which the secondary battery is composed as follows.
We take one or more of the oxides of lead that is under some circumstances we
use litharge, under some circumstances minium under some circumstances per
oxide of lead and under some circumstances one or more of them and we mix them
into a paste or creain with dilute sulphuric acid or in some cases with dilute
sulphuric acid which has been saturated with neutral salts so as to increase its
conductivity say for instanco, chloride of calcium or chloride of sodium and we
fill the porous cells in which the electrodes have been previously placed with this
cream or paste so as to allow of the said cream or paste being on the sides of the
respective elements which face each other.
When the cells are constructed by porous slabs secured in troughs as previously
described we fill them in the same way.
In certain cases we find it advantageous to mix more or less soluble salt of lead
such as chloride of lead with the mixed oxides of lead.
Having constructed the elements of the secondary battery in this way we fill the
spaces between the elements with dilute acid preferably sulphuric acid and proceed
to electrically form the elements as follows.
If we have used chloride of lead or other similar salt of lead with the mixture of
enlts of lead as last described we first pass a current from a dynamo inachine or
other suitable source of electricity in such a direction and to such an extent as by
hydrogenation of one plate to convert the proportion of chloride of lead which wo
have used into lead, in a metallic form which will be finely distributed through the
mass of oxides of lead then reversing the current and per oxidising the mixture of
oxides of lead and metallic lead present in these elements while at the same time
hydrogenizing the opposing elements and reducing them to the condition of lead in
a lower form of oxidation and probably partly lead in a metallic condition.
When we have not used Chloride of Lead or any similar salt this reversal of the
current is not necessary for this purpose but it is often advantageous to reverse
the current after the batteries have been charging for some short time with n
view of increasing the conductivity of the intermediate products which are formed
and which otherwise interpose considerable resistance to the rapid and, successful
charging of the battery.
In either case when the current has passed for a sufficient length of time to
strongly peroxide one set of elements and highly hydrogenize the opposite or
opposing set of elements the battery will be charged and may be used as a
secondary battery. It will retain its charge of electricity for a considerable length
of time and give it up when the wires connected with the terminals are brought in
circuit.
When the battery has been charged with electricity it is advantageous if it is
not required to be used immediately to draw off the, liquid and refill the cells when
it is required for use.

page_text: +
In many cases we prefer to prepare the oxides and salts of lead which we use
from Galena as described in our previous Specification but in that case we find it
is advantageous to treat the Galena which is being operated upon whether the
sail Galena has been roasted or has not been roasted with Hydrochloric acid mixed
with Chloride of Sodium or Chloride of Calcium so as to increase the solubility of
the Chloride of. Lead which is formed and we find that it is practically essential that
in every case the Galena or roasted Galena should be so treated at a boiling
temperature. By this means the Chloride of Lead or other salt formed, is extracted
in a more pure condition.
It is also desirable that the Galena to be treated should be very free from Zinc
or iron or other similar metal which night produce local action and so not only
diminish the efficiency of the Secondary Battery when formed but also cause' a
waste of power.when charging it.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said John. Evelyn Liardet and Thomas. Donnithorne in the Great Seal
Patent Office on the 19th April 1883.
JOHN EVELYN LIARDET of Brockley in the County of Kent and THOMAS
DONNITHORNE of Gracechurch Street in the City of London "IMPROVEMENTS IN
SECONDARY BATTERIES AND IN THE MANUFACTURE OF THE SAME
'23
We construct the electrodes of the elements of which the secondary battery is
composed of very thin sheets of pure metallic lead ie. instead of using the thick
leaden plates which are .customary in secondary batteries, we prefer to use the
thinnest pure metallic lead which we can obtain from the ores of lead and galena
taking such mechanical precautions as may be necessary to support its weight when
it is coated with the salts of lead whether mixed or not with finely divided metallic
lead.
In some cases we may use carbon plates as the electrodes but in those cases wo
prefer to use thin plates of dense carbon and charge the pores of this dense carbon
with the salt of lead afterwards reducing it as far as practicable to a metallic state
by electrolytic action so as to increase the conductivity of the carbon.
To prepare the secondary batteries we put a coating of suitable salts of lead
preferably prepared as hereinafter described upon the surfaces of these leaden or
carbon electrodes. We prefer to retain this coating in place either by putting the
electrode inside a porous cell similar in character to the porous cells in use in Groves
and other batteries but constructed so as to have the greatest practical amount of
porosity and in such form that when combined with sufficient strength-they will
retain the lead salts such cells being constructed of material which possesses low
conducting power.
In some cases we prefer to use porous plates constructed in a similar way which
plates are adapted to retain and support the salts of lead and are securely fixed in
grooves in cells or troughs of earthenware or slate or wood or other suitable
substance so as to form exterior cells in which the elements with the porous cells.or
plates may be immersed. One side of each of these cells i.e. the side of the
elements which are opposed to each other will be constructed of porous slabs or
plates while the exterior or other sides of the elements which are not opposed to
each other will be constructed of impervious non-conducting materials.
In other cases we prefer to construct the elements in a series of circular porous
-pots nested one inside the other the spaces between the circular porous pots forming
alternately the elements of the secondary battery and the spaces between the
separate elements to contain the dilute sulphuric acid or other exciting fluid
used.
Having thus constructed the cells and the electrodes we construct the elements
of which the secondary battery is composed as follows:-
We take one or more of the oxides of lead-that is under some circum-
stances we use litharge under some circumstances minium under some circumstances
another oxide of lead and under some circumstances one or more of them
and we mix them into a paste or cream or of the consistence of creain with
dilute sulphuric acid or in some cases with dilute sulphuric acid which
has been saturated with neutral salts so as to increase its conductivity say for
instance chloride of calcium or chloride of sodium and we fill the porous cells in
which the electrodes have been previously placed with this paste so as to allow of
the said paste being on the sides of the respective elements which face each
other.

page_text: When the cells are constructed with porous slabs or plates placed in troughs as
previously described we fill them in the same way.
In certain cases we find it advantageous to mix more or less soluble salt of lead
such as chloride of lead with the mixed oxides of lead.
Having constructed the elements of the secondary battery in this way we fill the
spaces between the elements with dilute acid preferably sulphuric acid or muriatic
acid and proceed to electrically form the elements as follows:-
If we have used chloride of lead or other similar salt of lead with the mixture of
salts of lead as last described we first pass a current from a dynamo machine or
from any other suitable source of electricity in such a direction and to such an
extent as by hydrogenation of one plate to convert the proportion of chloride of
lead which we have used into lead in a metallic form which will be finely distributed
through the mass of oxides of lead then reversing the current and peroxidising the
mixture of oxides of lead and metallic lead present in these elements while at the
same time hydrogenizing the opposing elements and reducing them to the
condition of lead in a lower form of oxidation and probably partly lead in a
metallic condition.
When we have not used chloride of lead or any similar salt of lead this
reversal of the current is not necessary for this purpose but it is often advantageous
to reverse the current after the batteries have been charging for some short time in
order to increase the conductivity of the intermediate which are formed and which
otherwise interpose considerable resistance to the rapid and successful charging of
the battery.
In either case when the current has passed for a sufficient length of time to
strongly peroxidize one set of elements and highly hydrogenize the opposite or
opposing set of elements the battery will be charged and may be used as a secondary
battery. It will retain its charge of. electricity for a considerable length of time
and give it up when the wires connected with the terminals are brought in
contact.
When the battery has been charged with electricity it is advantageous if it is not
required to be used immediately to draw off the liquid and refill the cells when it
is required for use.
In many cases we prefer to prepare the oxide and salts of lead which we use from
galena or other ores of lead as described in our previous specification but in that
case we find it is advantageous to treat the galena or lead ore which is being
operated upon whether the said galena has been roasted or has not been roasted
with hydrochloric acid mixed with chloride of sodium or chloride of calcium so as
to increase the solubility of the chloride of lead which is formed and we find that
it is practically essential that in every case the galena or roasted galena or lead ore
should be so treated at a boiling temperature. By this means the chloride of lead
or other salt formed is extracted in a more pure condition.
It is also desirable that the galena to be treated should be very free from zinc or
iron or other similar metal which would produce local action and so not only
diminish the efficiency of the secondary battery when formed but also cause a waste
of power when charging it
Having now described the nature of the Invention we will proceed to describe
the manner in which the same is to be carried into effect and may promise that
the aim or object of the modifications which we have introduced is to diminish the
weight of the elements or other portions of which secondary batteries are composed
and to increase the durability or efficiency of those batteries either by increasing
the conducting power of some portions of the active electrodes or by increasing the
amount of substance capable of acting as an electrode.
The electrodes of secondary batteries constructed according to this Invention are
compound in character consisting first of a backing of lead carbon or some other
suitable material really to serve as a conductor or collector of the electric currents
and secondly of an active portion of lead or oxides of lead or salts or other
:
"

page_text: compounds of lead the chemical constitution of which is capable of being changed.
under the influence of an electric current.
In most cases we prefer to use lead for the backing and in such cases we
diminish the weight of the backing very greatly by using extremely thin lead..
That which we have found most suitable for the purpose of small sized elements
is what is known as lead weighing about 1/4 to 1/2 lb per square foot. It will bo
Been that this weight presents a great contrast to the weight of the lead used with
the older form of secondary batteries which was often as high as 16 to 18 lbs per
square foot.
This thin lend. plate may with advantage in many cases be attached or fixed to
the divisions between the cells or elements of the batteries.
When we use carbon as the backing of the electrode we prefer to use very thin
plates of dense carbon instead of the tolerably thick plates of light porous carbon.
previously employed and we prefer to prepare this carbon for use as follows:-
We immerse the plates in a dilute solution of a soluble salt of lead say acetate of
lead or chloride of lead and boil, the plates in this solution to expel the air from
the pores or we extract the air from the pores by means of an air pump. We thus
fill the pores of the plates with the solution of lead salt and allow it to cool while
in the liquor. When cold the plates are removed from the liquor and the salt of
lead is reduced to a state of metallic lead either by a galvanic current or by decom-
position in a vessel of acidulated water in which a plate of zinc or other suitable
imetal is brought opposite to the plates of carbon.
In either case the result is the same as we obtain a plate of dense carbon the
pores of which are filled with metallic lead thereby greatly increasing its
conductivity and forming a better basis for the attachment of the working part of
the electrode.
These electrodes are now to be cut to a suitable thickness and coated with salts
of lead in a state suitable for peroxidizing or for hydrogenating as the case may be
or with oxides of lead in a peroxidized state and with metallic lead in a spongy or
crystalline state or with a mixture of all these and in each case whatever we adopt
it is our special object to ensure that the salts of lead or compounds of lead used are
free from metals or other impurities which would set up local action and so cause the
battery to work irregularly.
In order to keep the coating in place and prevent it from crumbling away under
the continued charging and discharging of the battery we prefer in every case to
use the porous plates or porous cells so manufactured as to retain and support the
salts of lead as herein before described fixed at a short distance from the backing of
the electrode.
We will now describe the mode in which we carry the manufacture of these
clements into practice, and how we apply the working portion, of the electrode.
We construct water tight troughs having say 10 divisions each so that each
division shall form a separate cell. A useful size for these cells is 12 inches deep
6 inches wide from side to side of the trough and 2 inches in the clear wide from
side to side of each cell with a division half an inch thick between each cell and
the adjoining cell. We shall thus obtain a tray having external dimensions of
about 2 feet 2 inches long 7 inches wide and 12 inches deep containing 10 cells
each 12 inches by 6 inches by 2 inches. These cells must be made of hard, wood
thoroughly jointed together with liquid india rubber solution or other suitable
waterproof composition and screwed with copper screws or bolts.
In each of the cells there must be formed from top to bottom and across the.
bottom 2 grooves or channels about / inch wide and 1 inch deep so that 2 porous
plates measuring 12 × 6 × ¼ inches thick can drop down into them. These
grooves should be in such a position that the plates should be about half an inch
apart. These plates will not require to be cemented into place provided they fit
fairly tightly
%. When each of the cella has been fitted with these porous plates we shall have a
tray ready for the introduction of the backing electrodes which is done as follows:―

page_text: The sheet of thin lead before referred to is cut to a size of 13. x 6 inches and is
passed down just inside of the external wooden ends of the trough until it touches
the bottom of the cell and is secured in its place by turning the top over and
fastening it with a sufficiency of copper nails.
A terminal screw is attached to this piece of lead.
Nine other pieces of lead are then cut each 24'/, x 6 inches and each of these is
doubled into the form of a U and inverted so that the open part is downwards and
dropped over the 9 divisions which divide the trough into 10 cells so that each of
these slips forms the backing of an electrode in two different cells the positive
electrode in one cell and the negative electrode in the other.
Another strip of lead 13%, x. 6 inches is put onto the last division and a
terminal screw fixed to this also.
The backing and terminals, of the cells are now complete.
In some cases we vary the construction of this trough as follows:-
Instead of putting two porous plates into each cell constructed as above described
we cut one broader groove in the ends of each cell and put in a porous cell in such
a way that the two sides of the flat porous cell may take the place of the two porous
plates and that the hollow plates of the porous cell itself may serve as the space
between the two porous plates.
Whichever way we have constructed our troughs and cells the central division
between the two porous cells is intended to contain the exciting liquid of the battery,
whether it be dilute sulphuric muriatic or nitric acids or whatever other suitable
liquid and the 2 external divisions are to contain the elements of the electrodes―- .
one the positive and the other the negative.
In charging these hollow electrodes we use salts or compounds of lead and as far
as practicable we prefer to use those which have been made directly from selected
ores of lead so that they may contain an acid mixture of foreign metals and
interfere less with the action by which we introduce spongy lead into them.
In many cases we prefer to use a mixture of peroxide of lead, minium and a
mixture of the lowest oxides of lead for the negative.
We will describe the composition charging on this assumption. We take the
necessary quantity of peroxide of lead and minium in the proportion of about
4 of the former to one of the latter both in a state of fine powder and admix
intimately with them one tenth of their weight of acetate of lead or chloride of
lead or other soluble salt of lead in a state of fine powder. We prefer however to
use the acetate. We mix the whole with dilute sulphuric acid (5 per cent acid
95 per cent water) or with water into a thick cream and pour it into the hollow
electrode and proceed in this way until all the positive electrodes are charged.
In a similar manner we grind the lower oxides of lead to a fine powder and
mix them with one tenth of their weight of by preference acetate of lead and mix
this into a paste with dilute sulphuric acid or water and pour it into the hollow of
the negative electrodes until all are filled
If we decide to use other salts of lead or other compounds of lead instead of the
oxides referred to the mode of procedure is identical although it may be necessary
in certain cases to use a different acid but we have specified the compounds of lead
which we think most likely to be used and the admixture of the salt of lead which
will most likely be beneficial.
We can if we please mix some neutral salt such as chloride of sodium or chloride
of calcium with the liquid so as to increase the conductivity of the mass and of
the porous cells.
We proceed to reduce the acetate of lead or other suitable salt of lead to metallic
lead in one or other of the following ways.
First in the centre division of each cell between the 2 porous plates we place a
plate of zinc and we fill this division with water and from time to time for some
hours we draw off this water and replace it by fresh water. The acetate of lead
will become decomposed the acetic acid pass over to the zinc and the lead reduced
to the form of spongy metallic lead which will be distributed through the mixed

page_text: oxides of lead in such a way as to greatly increase their conductivity and combine
them together as a compact but very porous electrodo.
When this process is to be adopted it is desirable in fact almost essential that
the acetate, of lead, and the salts of lead should have been mixed into a paste with
water instead of dilute acid.
Or we may reduce the acetate of lead by means of an electric current passed
alternately through the whole of the positive electrodes in one tray and then
through the whole of the negativo electrodes the current being collected in each
case by temporary electrodes placed between the porous plates.
Whichever way is adopted the same result would be obtained.
The next thing is to proceed to form the battery.
To do this the interior cells between the porous cells must be filled with dilute
sulphuric acid and a current passed through the cells as in the ordinary form of a
Planté or Faure Battery observing somewhat, similar precautions to those which
are always necessary in secondary batteries vis that the formation must take place
very slowly at first and that it is not desirable to carry the charging to the
extreme on the first occasion but rather to let the batteries slowly discharge
through a resistance and recharging then again before charging them to their full
power.
It would be found very advantageous to renew the acid, 2 or 3 times so as to
ensure the removal of the acetic acid which may have been left.
Sometimes it is advantageous to reverse the direction of the charging current
for a few minutes as it appears to increase the conductivity and certainly improves
the homogeneity of the mass in the cells.
When the batteries have been charged and discharged twice they may be fully
charged by a dynamo taking care that the current is not passed in too rapidly.
The charging may be continued until the resistance of each cell has fallen to one
tenth of an Ohm.
The batteries will then be completed and will retain their charge for a
considerable time.
If they are required to be set aside for months without use it is advantageous
to draw off the acid from the cells and replace it when they are wanted to be
discharged.
Having thus described the nature of our said Invention and the manner of
performing the same we would have it understood that we claiin:-
First Construction and manufacture of secondary batteries for the storage of
electricity substantially as herein before described.
Second. The use of soluble salts of lead in conjunction with oxides of lead or
other compounds of lead in secondary batteries as herein before described and the
reduction of these soluble salts of lead to the state of spongy lead in the lead salts.
contained in the elements substantially as herein before described.
Third. The use of finely divided spongy lead and the formation of spicules of
lead chemically produced in the electrodes of secondary batteries in order to
increase their conductivity substantially as herein before described.
In witness whereof we the said John Evelyn Liardet and Thomas Donnithorne
have hereunto set our hands and seals this Nineteenth day of April in the
vear of our Lord One thousand eight hundred and eighty three.