Improvements in and in the Manufacture of Plates for Electric Accumulators or Secondary Batteries.
Year: 1895

page_text: Date of Application, 21st Oct., 1895
Complete Specification Left, 21st July, 1896-Accepted, 12th Sept., 1896
PROVISIONAL SPECIFICATION.
Improvements in and in the Manufacture of Plates for Electric
Accumulators or Secondary Batteries.
I, JOHANNES KÖRNER, of No. -9, Lit. Q. VII Mannheim, in the Empire of
Germany, Engineer, do hereby declare the nature of this invention to be as
follows:-
The many improvements in secondary batteries hitherto effected related either
to special forms of the grids, latticed plates or supports for the paste, or to the
composition of the latter, or to the devices for constructing the finished electrodes ;
but hitherto no efforts have been made to protect from the destructive action of
the electrolyte, tho grids, latticed-plates, or supports, and conductors of the electric
current in order to impart to the accumulator an almost unlimited duration of life, as
the duration of life of the accumulator depends on the maintenance of these grids, or
supports in their original condition.
This invention has for its object, by the use of sulphate of potash in the
electrolyte, to cover the above mentioned supports for the paste or active material
and the conductors in electric accumulators of all kinds, with a protective coating
against the destructive action of the electrolyte, such coating consisting of fiue
crystals of sulphate of potash and acid sulphate of potash, whereby the duration of
life of the accumulator is considerably prolonged.
It will be evident from the following specification in what manner this is
attained.
The conductors for the olectric current, in the form of grids, boxes or frames of
various sections or as plates with even or uneven surfncos serve also as supports for
the paste or active material. Before these conductors are coated with the paste
which accumulates the current, they must be protected in some suitable manner
against the electrolyte in order that the duration of life of the accumulator inny not
be very considerably shortened by their destruction. In order to obtain this
protection of the conductors, a deposit of crystals of normal sulphate of potash and
acid sulphate of potash has been found to be the most suitable, as these crystals in
consequence of their great hardness in contrast to sulphate of soda, for instance,
have much less tendency to again dissolve.
With
The grids or supports are inserted in a vessel in alternating succession of
negative and positive plates in the usual manner and are metallically connected.
In this vessel sulphuric acid is poured, to which sulphate of potash is then added
and an electric current is discharged into it until the liquid becomes warın.
the increasing heat of the electrolyte, its property for dissolving the sulphate of
potash also increases and continues as long as the solution is not fully saturated.
A portion of the sulphate of potash is converted precisely by this heating into
acid sulphate of potash, which as a consequence of the electrolytic action of the
electric current passing through the liquid, is deposited in the form of rhombic
pyramids on the conductors. As the surface of the conductors becomes pitted
under the electrolytic action of the current, the aforesaid crystals adhere more
firmly, and then to a certain extent an amalgamation as it may be called of
the crystals with the conductor which is pitted on its surface, takes place.
After the layer of crystals has set, and become sufficiently thick, the grids,
latticed-plates, or supports are ready for conting with the paste or active material.
The finished electrodes are then, during the period of formation, immersed in

page_text: a bath of the same composition, and charged with current in such a way that
the bath again becomes heated and thereby as much sulphate of potash as possible
is brought into a soluble condition. Here again as a consequence of the electro-
lytic action of the current each particle of the paste is also enclosed with a
crystalline coating.
This coating with crystals of sulphate of potash produces, in addition to a
considerable diminution of the inner resistance, a thorough contact of the paste
with the conductor and the hardness of the crystal's renders it more difficult
for the active substance to fall off. It is therefore necessary for the practical
use of the accumulator that sulphate of potash be always present in excess in the
electrolyte.
Dal thin 101k ton of 100
COMPLETE SPECIFICATION.
Improvements in and in the Manufacture of Plates for Electrio
Accumulators or Secondary Batteries.
1, Johannes Körner of No. 9 Lit. Q. VII Mannheim in the Empire of
Germany, Engineer, do hereby declare the nature of this invention and in what
manner the same is to be performed, to be particularly described and ascertained
in and by the following statement :—
The many improvements in secondary batteries hitherto effected related either
to special forms of the grids, latticed-plates or supports for the paste, or to the
composition of the latter, or to the devices for constructing the finished electrodes;
but bitherto no efforts have been made to protect from the destructive action of the
electrolyte, the grids, latticed-plates, or supports, and conductors of the electric
current, in order to impart to the accumulator an almost unlimited duration of life,
as the duration of life of the accumulator depends on the maintenance of these grids,
or supports, in their original conditiou.
This invention has for its object, by the use of sulphate of potash in the electro-
lyte, to cover the above mentioned supports for the pasto or active material and the
conductors in electric accumulators of all kinds, with a protective coating against
the destructive action of the electrolyte, such coating consisting of fine crystals of
sulphate of potash and acid sulphate of potash, whereby the duration of life of the
accumulator is considerably prolonged.
It will be evident from the following specification in what manner this is
attained.
The conductors for the electric current, ia the form of grids, boxes or frames
of various sections or as plates with eveu or uneven surfaces serve also as supports
for the paste or active material. Before these conductors are coated with the
paste which accumulates the current, they must be protected in somo suitable
manner against the electrolyte in order that the duration of life of the accumulator
may not be very considerably shortened by their destruction. In order to obtain this
pirotection of the conductors, a deposit of crystals of normal sulphate of potash and
acid sulphate of potash has been found to be the most suitable, as these crystals in
cbusequence of their great hardness in contrast to sulphate of soda, for instance;
have much less tendency to again dissolve.
The grids or supports are inserted in a vessel in alternating succession of
negative and positive plates in the usual manner and are metallically connected.
In this vessel sulphuric acid is poured, to which sulphate of potash is then addod.
and an electric current is discharged into it until the liquid becomes warm.

page_text: With the increasing heat of the electrolyte, its proporty for dissolving the
sulphate of potash also increases and continues as long as the solution is not
fully saturated. A portion of the sulphate of potash is converted precisely by
this heating into acid sulphate of potash, which as a consequence of the electrolytic
action of the electric current passing through the liquid, is deposited in the form
of rhombic pyramids on the conductors. As the surface of the conductors
becomes pitted under the electrolytic action of the current, the aforesaid
crystals adhere more firmly, and then to a certain extent an amalgamation as it
may be called of the crystals with the conductor which is pitted on its surface
takes place.
After the layer of crystals has sct, and become sufficiently thick, the grids,
latticed-plates, or supports are ready for coating with the paste or active material.
The finished electrodes are then, during the period of formation, immersed in a
bath of the same composition, and charged with current in such a way that the
bath again becomes heated and thereby as much sulphate of potash as possible is
brought into a soluble condition. Here again as a consequence of the electrolytic
action of the current cach particle of the paste is also enclosed with a crystalline
onating.
This coating with crystals of sulphate of potash produces, in addition to a
considerable diminution of the inuor resistance, a thorough contact of the paste
with the conductor and the hardness of the crystals renders it more difficult
for the active substance to fall off. It is therefore necessary for the practical use
of the accumulator that sulphate of potash be always present in excess in the
electrolyte.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed; 1 declare that what I
claim is :-
1. The improvement in the manufacture of plates for electric accumulators_or
secondary batteries, consisting in exposing the carrying frames, plates, or grids,
before they are coated with the active material or paste, to the action of the electrio
current in a solution of sulphate of potash and sulphuric acid in order to deposit a
crystalline coating thereou, for the purpose of protecting them from the destructive
action of the electrolyte, substantially as set forth.
2. Plates for electric accumulators or secondary batteries, consisting of grids or
other carriers or conductors coated with a protective layer composed essentially of
acid sulphate of potash, substantially as described.
Dated this 20th day of July 1898.
WM. P. THOMPSON & Co.,
Of 6, Lord Street, Liverpool, Agents for tho Applicant.