An Improved Process for the Preparation of Electrodes for Primary, Secondary, and Dry Batteries.
Year: 1895

page_text: Date of Application, 26th Sept., 1895-Accepted, 11th Jan., 1896
COMPLETE SPECIFICATION.
An Improved Process for the Preparation of Electrodes for Primary,
Secondary, and Dry Batteries.
We, HENRY LEITNER, Philologist and EMANUEL REICHER, Actor both of
Nieder-Schönhausen 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 process forming the subject of the present application for Letters Patent
has for its object the preparation of an electrode, possessing an immense capacity
relatively to its volume and weight, and moreover great hardness, so that it is
very resistant to external influences.
By means of the process hereinafter set forth a completely homogeneous
relatively efficient and strong lead peroxide mass is obtained, which
"
combined
with a carbon body in so intimate a manner, that whilst there still exists a
separate carbon body and peroxide body respectively, there is an extremely
efficacious contact between them. The process is preferably carried out in the
following manner :-
In
To an oxide of lead mass in a pasty condition there is added a small percentage
of carbon dust to ensure electrical conductivity throughout the compound.
addition to the carbon dust any suitable binding material for instance glycerine is
added and the mass thus composed, which is relatively a good conductor can be
moulded by pressure into a solid body, composed principally of lead oxide. In
order however to fully adapt it for the purposes intended, the lead oxide mass must
be converted into peroxide by further oxidation.
Experiments have proved that this further oxidation is best accomplished by
subjecting the mass to the action of an approximately saturated solution of sodium
hypochlorite, conveniently prepared by adding bleaching powder to saturated
sodium carbonate solution. If after this an electric current be passed through
the mass the same becomes thoroughly peroxidised throughout and the glycerine is
removed, without in any way damaging the firmness of the inass.
If before the mass is exposed to the above process small rolls of lead, preferably
made of rolled-up lead foil, be pushed into the mass, these rolls are thoroughly
oxidised, whilst being firmly supported so that they cannot fall to pieces. As
already stated the above described lead oxide mass is whilst still in a pasty state,
that is previous to peroxidation, pressed into a hollow carbon body under great
pressure in such a manner that the same penetrates the pores of the receptacle
and secures a thoroughly effective contact therewith.
When an electrode prepared in the above manner is subjected to the action of
acidulated water and connected with a zinc electrode, a source of current is
obtained distinguished by its capacity and intensity (2.5 volts).
The electrode prepared according to the manner above set forth, is advantageously
converted into an element as shewn in the accompanying drawing by enclosing it
in an envelope c with bottom d made of insulating material; a represents the carbon
mass and 6 the lead peroxide. In the centre of the hollow space is provided an
acid proof rode on which is placed a leaden tube f. Upon this latter chemically
pure zinc g is deposited, forming the second electrode. In order to set the element
thus constructed in operation, it is only necessary to pour dilute sulphuric acid,
alum solution or the like into the hollow space. By means of this zinc electrode,

page_text: the heavy and voluminous negative lead plate usual in accumulators can be
dispensed with. The carbon body is preferably made tubular and forms the outer
envelope whilst the lead peroxide mass, also tubular in shape forms an extremely
intimate inner lining to the same, as shewn in the accompanying drawing.
Having now particularly described and ascertained the nature of our said inven-
tion, and in what manner the same is to be performed, we declare that what we
claim is :-
1. The process for the construction of a lead peroxide and carbon electrode,
consisting essentially in oxidising an oxide of lead mass mixed with carbon dust
and made electrically conductive, with addition of a binding medium (glycerine), and
pressing same into a carbon body in such manner that a compact mass is formed
consisting partly of carbon and partly of conducting peroxide of lead.
2. The use of sodium hypochlorite for effecting the further oxidation of the
mass described in Claim 1 with the addition of metallic lead slips inserted, whereby
an efficient oxidation is secured without endangering the strength of the mass.
Dated this 26th day of September 1895.
W. P. THOMPSON & Co.,
31, High Holborn, London, W.C., Patent Agents for the Applicants.