Improvements in Plates or Electrodes for Accumulators.
Year: 1894

page_text: Date of Application, 7th Apr., 1894-Accepted, 2nd June, 1894
COMPLETE SPECIFICATION.
Improvements in Plates or Electrodes for Accumulators.
I, ROBERT JACOB GÜLCHER of 18, Kantstrasse, Charlottenburg 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 :-
This invention relates to the manufacture of peculiar plates or electrodes for
accumulators, and has for its object to obtain as great a capacity and durability
(life) in the accumulators as possible. The invention further affords the extremely
valuable property of a very light weight.
The improvement consists in that instead of conveying the active substance on
to plates, or compressing it into lattice work, as has hitherto been done, it is
introduced on and between the fibres of woven, knitted, or otherwise produced
fabrics, such as felt and the like. The fibres may be of natural as well as
artificial origin.
By this means the active substance is retained by the fibres of the fabric, and the
effective layer thus formed is extremely porous and has a very great firmness in
spite of its flexibility. Further the electrolytic fluid can easily penetrate into its
interior by capillary attraction, so that in this way an even action is obtained on all
parts of the active substance.
This invention may be carried out in various ways.
For instance, the fabric in question may be impregnated with a paste formed of
oxide of lead and diluted sulphuric acid, and the oxide of lead may then be formed
into effective layers by means of the electric current. By this and similar
processes as well as by the direct impregnation of the fabrics with metallic lead
(lead dust), the lead does not adhere so firmly to the fibres, and is not so finely
distributed in the fabric as by the following process:- -This process, which
repeated experiments have shown to be the most preferable, consists in producing
on and between the various fibres of the fabric a spongy lead by chemical means.
For this object, the fabric, which, for instance, may preferably consist of sheep's
wool slightly or not at all felted (fulled) and of the form and size of the plates or
electrodes which are to be produced, is impregnated with sulphate of lead. This
is attained either by saturating the fabric first with a concentrated solution of
acetate of lead and then placing it in a bath of diluted sulphuric acid, sulphate of
lead being then deposited on and between the fibres of the fabric, or by pressing a
paste of sulphate of lead and distilled water directly into the fabric in such a way
that it thoroughly penetrates the same and also covers its surfaces.
The fabrics impregnated with sulphate of lead are then placed between zinc
plates of suitable size and immersed in a somewhat inclined position in a bath. This
fatter consists of a solution of common salt, or of water slightly soured with
sulphuric acid. In this bath all the sulphate of lead, according to the thickness
of the fabric, is converted, within one or more days, into spongy lead, which
very firmly adheres in an extremely finely divided condition to the fabric employed.
As the spongy lead easily remains adhering to the zinc plates, on the fabrics
being removed, a smaller or greater part of the spongy lead formed would be
easily torn off. In order to prevent this, the surfaces of the zinc plates against
which the material rests, are preferably coated with filter paper through which the
chemical action proceeds in a perfectly satisfactory manner. As soon as all the
sulphate of lead contained in the fabrics is converted into spongy lead in the manner
herein before described, the fabrics thus obtained only need to be thoroughly

page_text: washed in order to allow of their being immediately used as plates or electrodes for
accumulators.
The negative electrodes then are quite ready for use, whilst the positive merely
require to be exposed to the oxidising action of the current. The positive and
negative electrodes may also first be put together in a condition of pure lead and
only then the positive plates be converted into superoxide of lead by the first
charging current. This conversion takes place very quickly however on account
of the extremely fine subdivision of the lead and more particularly on account of
the spongy lead being very easily oxidised.
The attachment of the electrodes prepared according to this invention, to suitable
conducting pieces and the connection of the same with one another may take place
in any suitable way without the essential part of this invention being thereby
modified in any way.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what I
claim is-
Improved lead electrodes for accumulators, consisting of supports formed of
woven, knitted or the like material, which is non-conducting, and which resists the
electrolytic liquid, on and between the fibres of which material first sulphate of
lead is either deposited by chemical means or into which a paste of sulphate of lead
and water is introduced and the sulphate of lead subsequently reduced to spongy
lead, substantially as described.
Dated this 6th day of April 1894.
W. P. THOMPSON & Co.,
Of 6, Lord Street, Liverpool, Agents for the Applicant.