Improvements in Electric Accumulators.
Year: 1893

page_text: Date of Application, 4th May, 1893-Accepted, 9th Dec., 1893
COMPLETE DIVIFICATION.
Improvements in Electric Accumulators.
I, FRIEDRICH WILHELM ELLERMANN, of 19, Aber Donau Strasse, Vienna, in
the Austrian Empire, 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 :-
"3
This invention relates to electric accumulators; its objects being to produce an
accumulator having, with comparatively small volume and weight, a considerably
higher capacity than that of the accumulators hitherto used, wherein moreover the
dangers of "short-closing ' are entirely avoided, and which is so to speak dry,
inasmuch as the plate does not hang in an electrolyte, but the greater part of the
fluid necessary for maintaining the electrolytic action is stored up in the plate
itself.
These objects are attained by applying an active porous mass in a comparatively
thick layer; electrically connecting the individual particles of such mass by means
of mercury so as to reduce the resistance; and, for the purpose of avoiding too
rapid a discharge, adding to the mass a finely-divided electrolytically inert body.
With a view to making the "active" mass (preferably consisting of an oxide of
lead, such as litharge or peroxide of lead) as porous as possible, a salt, soluble in
the electrolyte, especially sodium or magnesium sulphate, is added to the substances
used in the preparation of that mass; such combinations or bodies as do not exercise
a prejudicial influence on the electrolyte either by chemical or by electric action
being most advantageously employed. These salts or bodies are soon dissolved by
the liquid and eliminated from the mass, so that interstices or pores filled up by the
electrolyte remain. The addition of sulphates of light metals, such as sodium and
magnesium, serves to prevent the formation of insoluble sulphate of lead in the
pores of the mass, as the sulphates decompose and give up sulphuric acid to the too
much diluted acid of the electrolyte, and absorb such sulphuric acid again when
the electrical discharge takes place. In order to bring into closer contact with
each other the particles of the mass separated by the interstices or pores, and
thereby to increase the working capacity, a mercury compound, sulphate of
mercury being specially suitable, is added; the globules of mercury which form
under the influence of the current acting as electrical conductors.
For the prevention of too rapid a discharge, thereby avoiding the objectionable
effects of short-circuiting, a body (preferably peroxide of manganese), indifferent or
neutral in regard to electrolytic action, is intimately mixed with the mass in a
finely divided condition; such body being calculated to retain the available
quantity of current with great tenacity, while any increased resistance that may
result therefrom is compensated for by the mercury globules above alluded to.
Where the mass is applied in a very thick layer, nearly the whole of the
electrolyte may be stored up within the pores or interstices thereof, so that
practically a dry accumulator is obtained. The remainder of the electrolyte is
absorbed by asbestos dust which receives the accumulator-plates.
The improved accumulator mass is preferably prepared as follows:-
The positive mass is composed of

page_text: 70 parts water), moulded and pressed into plates, which are dried and enveloped in
sheets of lead; these not only preventing the mass crumbling or frittering away,
but also serving to properly distribute or collect the electric current during the
operation of charging or discharging.
The negative mass is prepared from the following ingredients :—
These ingredients are mixed and treated like those of which the positive mass is
composed.
The construction of accumulators by means of electrode plates prepared as herein
stated is carried out in the usual manner.
1 kilogramme of positive mass gives 50 ampère-hours. The charging takes
place at the rate of ampère per square metre of surface, and the discharge at the
rate of from 2 to 3 ampères per square metre.
Before being fitted together, the finished plates are placed in water (which should
be frequently renewed) for a period of from 8 to 14 days, so as to remove the
greater part of their sodium and magnesium combinations.
Having now particularly described and ascertained the nature of this invention
and in what manner the same is to be performed, I claim :-
1. In the manufacture of an accumulator, adding to the ingredients of the
"active" mass, which preferably consists of oxides of lead, such as litharge or
peroxide of lead, bodies soluble in the electrolyte, more especially soluble sulphates
of light metals, such as sodium and magnesium sulphates, in the proportion given or
thereabouts, and subsequently removing these bodies by means of a solvent for the
purpose of producing pores or interstices in that mass.
2. In high-resistance-accumulators, adding to the "active" mass a mercury com-
pound, more especially sulphate of mercury, and preferably in the proportion
stated, for the purpose of enhancing the conductibility of that mass owing to the
presence of mercury eliminated by the action of the current.
1...
3. In accumulatora of great capacity, the addition to the "active"mass of an
electrolytically inert substance, especially peroxide of manganese, preferably 'in the
proportion stated, for the purpose of counteracting the injurious effects of 'short-
circuiting.
4. An electric accumulator substantially as herein described, the same comprising
an "active" mass made porous in the manner set forth and containing a mercury
compound and an electrolytically inert substance.
Dated the 4th day of May 1893
G. G. M. HARDINGHAM,
191, Fleet Street, London, E.C., Chartered Patent Agent.