IMPROVEMENTS IN THE MANUFACTURE of SECONDARY BATTERIES."
Year: 1882

page_text: LETTERS PATENT to Alexander Muirhead of Regency Street in the City of
Westminster, for an invention of "IMPROVEMENTS IN THE MANUFACTURE of
SECONDARY BATTERIES."
PROVISIONAL SPECIFICATION left by the said Alexander Muirhead at the
Office of the Commissioners of Patents on the 6th June 1882.
ALEXANDER MUIRHEAD of Regency Street in the City of Westminster.
PROVEMENTS IN THE MANUFACTURE OF SECONDARY BATTERIES:
"IM-
This Invention relates to improvements in the preparation or formation of the
metallic electrodes employed in the construction of secondary batteries of the
Planté type whereby economy in time and cost of production are obtained.
In carrying out, this invention the formation of the active surfaces of the lead
plates is effected by decomposing electrically a solution of a salt of lead such as the
acetate which is kept flowing in a continuous stream during the electrolysis
between the two sets of plates to form the electrodes of the battery and these
plates are coupled with a dynamo-electric machine or other suitable electric source.
A rapid and uniform deposition of peroxide of lead on one set of plates and of
finely subdivided metallic lead on the other set is thereby produced.
A small percentage of phosphoric or tartaric acid is sometimes added to the
solution of lead salt to increase the coherency of the precipitated lead on the
negative pole. Before passing the same solution past the plates a second time care
is to be taken to neutralize the free acetic acid formed during electrolysis as the
presence of such acid tends to prevent the formation of the peroxide of lead on the
positive pole.
Secondary cells built up of plates formed in the above manner are charged in the
usual way with a solution of sulphuric acid in water.

page_text: '
SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Alexander Muirhead in the Great Seal Patent Office on the
6th December 1882
ALEXANDER MUIRHEAD of Regency Street in, the City of Westminster. "IM-.
PROVEMENTS IN THE MANUFACTURE OF SECONDARY BATTERIES
"
My Invention relates to Improvements in the preparation or formation of the
metallic electrodes employed in the construction of secondary batteries of the
Planté type.
I effect the formation of the active surfaces of the plates employed in such
batteries by decomposing electrically a solution containing lead whilst the solution
is flowing in a stream past the plates.
In this way I produce upon the plates deposits of finely subdivided metallic lead
and deposits of peroxides of lead in condition such as to render the plates well
fitted to serve as the electrodes of secondary batteries.
The following is the manner in which I prefer to proceed. I find it best in the
first instance to obtain a metallic deposit on all the plates.
I take a large electro plating vat and I arrange within it against its two
opposite sides, the leaden plates which are to be prepared for use in the secondary
battery. All these plates I connect together and to a conductor passing out of the
vat. I place also in the vat between the two opposite sets or series of plates and
in a vertical position a large leaden plate, almost as long as the vat and as wide as
it is deep. This plate forms almost a partition dividing the vat longitudinally into
two equal parts but it is not to touch the ends or bottom of the vat and free space
is left for the flow of the liquid with which the vat is charged. This leaden plate
or partition is connected with another conductor.
I charge the vat with a solution of prot-oxide of lead in caustic potash
(P. b O + K. HO.) and containing say ten per cent of prot-oxide of lead. The
solution is admitted from an elevated cistern to the bottom of the vat, and an
over flow is allowed from the top. The overflow is into a cistern in which there
should always be some undissolved and finely divided oxide of lead to keep the
solution saturated with the metal. The overflow cistern is so mounted that when
full it can be raised above the electro plating vat, and the liquor drawn from it to
provide the continuous stream of solution, which I always maintain through the
electro plating vat and which I find to be necessary in order that the deposit may
take place uniformly and in proper condition. The stream need not be rapid; but
it should be such that the solution shall not be materially weakened in its passage
through the vat.
These arrangements having been made the two conductors are coupled with a
dynamo-electric machine, the plates being made positive and the central leaden
partition negative. On the current passing metallic lead in suitable condition is
deposited on all the plates. When it is judged that the coating is sufficiently
thick the vat is emptied and' the connection between the two sets or series of
plates on the two sides of the vat is removed. Each set or series of plates is then
to be separately connected with the dynamo-electric machine so that when the
machine is next set in motion. one set or series of plates may remain positive,.
whilst the other set or series becomes negative. The central leaden partition
remains without connection with the machine. The electro plating vat is now
charged as before but with a different solution viz: a solution of sulphate of lead
in dilute sulphuric acid, a solution containing say twenty per cent of H₂ S.O, and
as much sulphate of lead as this will dissolve.
.

page_text: This solution is used in the manner already described a stream of it being
caused to flow constantly through the electro plating vat so long as the machine is
at work.
The overflow is received into a cistern containing finely divided oxide of lead
and from this cistern when it is full the supply for the electro-plating tank may in
turn be drawn. After a time it will be found that the whole of the deposit upon
the negative plates is converted into peroxide of lead whilst but little change
beyond an advantageous consolidation of the surface of the metallic coating has
occurred to the positive plates. The operation is now complete; the plates are,
withdrawn from the electro plating vat and are arranged in the secondary battery
cells which are charged as usual with dilute sulphuric acid. The ordinary
couplings are provided and the secondary battery is then ready for use.
What I claim is the preparation or formation of the metallic electrodes of
secondary batteries by placing the plates in a vat through which a stream of a
solution containing lead is caused to flow and then producing deposits upon the
plates from the said stream of solution by the electrolysis of the liquid substantially
as described.
I also claim the manufacture of a secondary battery by arranging a number of
plates in a vat and coating them simultaneously by the electrolysis of a solution
containing lead and then arranging the plates in pairs in the separate secondary
battery cells.
In witness whereof I the said Alexander Muirhead have hereunto set my
hand and seal this Sixth day of December in the year of our Lord One
thousand eight hundred and eighty two.