Improved Filling Mass or Active Material for the Production of Solid Accumulator Plates.
Year: 1899

page_text: Date of Application, 22nd Sept., 1899-Accepted, 28th July, 1900
1.
COMPLETE SPECIFICATION.
Improved Filling Mass or Active Material for the Production of Solid
Accumulator Plates.
We, CARL FRIEDRICH PHILIPP STENDEBACII, Electrician, of 45, Plagwitzer-
strasse, Leipzig, and HEINRICH MAXIMILIAN FRIEDRICH REITZ, Landed Proprietor,
of Dewitz-Dobitz, near Taucha, Leipzig, in the Empire of Germany, 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 chief defects in the active material for accumulators of the kind hitherto
employed consist, as is known, in the inserted filling material not being very
porous and not adhering quite firmly to the supports. The first of these defects
is especially observable in plain pressed plates, which latter certainly show a
higher capacity but only allow of a slight current tension, about 0.36 amperes per
square decimeter of surface, whilst this tension, in perforated electrodes can be
generally increased to twice the extent, that is, to about 0.70 to 0.80 amperes
per square decimeter of positively flat surface.
If this tension be increased upon the charging or discharging of the plates.
there is in both cases, a great loss of energy and, further, in the latter case,
appearances as of explosions in the interior of the plates to be taken into con-
sideration, the consequence of which is that the active material falls out of the
support and the whole plate is thereby destroyed.
The reason of this is that the filling acid, owing to the mass being but
slightly porous, does not penetrate uniformly to all the parts thereof, for which
reason, only one part of the same, and that the outer, can participate in the
chemical conversion, when the charging and discharging are effected and, in
consequence of this, the conversion is effected in a continuously smaller degree,
the further it extends into the interior of the plate.
From this it also follows that only plates of moderate thickness can be pre-
pared and that, if it be desired to combine higher capacity with greater tension,
it becomes necessary to select thin, and therefore, a large number of plates,
which, again, leads to an increase in the deadweight of an element and also to a
considerable increase in the cost of production.
By means of the new filling material, all these disadvantages and the direct
consequences thereof are obviated.
This material, in consequence of its highly porous nature allows the filling acid
to reach all its parts, whereby the plate can be advantageously used even to
the farthest interior thereof The capacity of such a plate remains almost the
same when the discharge current, that is to say, the current tension is increased
to twice the extent and more per square decimeter, that is, to about 1.5 to 2
amperes per square decimeter of positively flat surface.
By means of this arrangement it is consequently possible to produce plates of
any desired thickness, that is, to combine great capacity with great tension and
in consequence of this, to reduce the weight and the costs of production of an
element

page_text: In order to ensure this high degree of porousness and the strength of the mass,
is desirable, before the material is spread in, the supports, in other words,
before the same is pressed into a solid plate, to add to the known preparations,
peroxide of lead, litharge and the like, a quantity of saccharine matter, suit-
ably to the desired degree of porousness, in addition to the usual binding
materials, (glyceric-sulphuric acid) and preferably in the form of syrup.
If other substances besides glyceric-sulphuric acid (a mixture of glycerine &
sulphuric acid, the sulphuric acid serving to clean the frame or skeleton when
the filling material is introduced, while the glycerine is intended to promote the
connection) be employed as binding materials, or if the formation of the plates
is to take place as quickly as possible after the spreading on of the material, that
is, if no long drying process is to be gone through, the plates dried in the air
- are preferably steeped in linseed-oil before being formed, in order that the filling
acid, at the beginning of the formation, may not too strongly penetrate them
during the first few minutes of this process, and thus cause the not yet sufficiently
hardened material to fall out, which is avoided by the oil absorbed by the plates,
the oil dissipating only gradually during the formation and constantly making
further particles of the material.accessible to the filling acid and the charging
current.
Having now particularly described and ascertained the nature of our said
invention and in what manner the same is to be performed, we declare that
what we claim is:-
Production of a highly porous and very strong filling material for accumu-
lators, the distinguishing feature of which is that, in the production thereof, a
quantity of saccharine matter, suitable to the desired degree of porousness, is
added thereto, preferably in the form of syrup, and which material, otherwise,
is as described.
T11
กด 1 1
WHEATLEY & MACKENZIE,
40, Chancery Lane, London, W.C., Agents.