KRUVIDIONAL DIE
Year: 1893

page_text: Date of Application, 3rd Mar, 1893:
Complete Specification Left,.4th Dec., 1893-Accepted, 13th Jan, 1894)
KRUVIDIONAL DIE
Improvements in the Manufacture and Production of Elements
for Secondary Batteries.
:. I
We, THE LITHANODE AND GENERAL ELECTRIC COMPANY LIMITED. of
11. Abchurch Lane, in the City of London and JOB THOMAS NIBLETT of.
64 Millbank Street in the City of Westminster, Electrical Engineer do hereby
declare the nature of our invention to be as follows:-
-
This invention relates to secondary battery elements (and more especially to the
positive plate or element) of the kind known as lithanode. This material as
produced prior to this invention has been of a dense character which has had great
electrical capacity but has necessited. slow discharge to utilize the. full' current
capacity of the battery. It is the object of this invention to provide a lithanode
element which overcomes this objection and this we. effect by employing in the
manufacture an inert material or salt which will afterwards be removed or dissolved
out and will leave the element in the condition of porous lithanode presenting large.
surface to the electrolyte.
A suitable salt for the purposes of this invention is sulphate of magnesia.
Presuming that sulphate of ammonia is used with the litharge in the making of the
lithanode we prefer to take the litharge and the sulphate of ammonia and the
sulphate of magnesia in a dry state and to thoroughly incorporate them and to
place the mixture in a mould. in this dry condition and then exert pressure upon it
with the intervention of felt or other material containing water or liquid which will
decompose the sulphate of ammonia forming lithanode containing in it'the crystals
or grains of sulphate of magnesia and when the element is removed from the mould
this crystals or grains are removed or, dissolved out leaving the lithanode in the
desired porous condition. Although we have mentioned sulphate of ammonia and
sulphate of magnesia we do not limit ourselves to these salts as any other
suitable matter or matters may be used which will provide the necessary sulphuric
acid for hardening the element into lithanode and the inert crystals or grains
which on removal or dissolving out leave the lithanode in the requisite, porous
condition.

page_text: performed to be particularly described and ascertained in and by the following
statement :-
This invention relates to secondary battery elements (and more especially to the
positive plate or element) of the kind known as lithauode. This material as produced
prior to this invention has been of a dense and hard character which has had great
electrical capacity but from its comparative impermeability and low conductive
power has necessitated slow discharge to utilize the full current capacity of the
battery in which it is employed. It is the object of this invention to provide a
lithanode element which overcomes this objection and this we effect by employing
in the manufacture an inert or comparatively inert material or salt which will
afterwards be removed or dissolved out and will leave the element in the condition
of porous lithanode presenting a greatly enlarged surface of exposure to the action
of the electrolyte.
A suitable salt for the purposes of this invention is sulphate of magnesium.
Presuming that sulphate of ammonium is used with the litharge in the making
of the lithanode we may carry the invention into effect by taking the 'litharge
and the sulphate of ammonium and the sulphate of magnesium in a dry..and more
or less triturated condition and after thoroughly incorporating them placing the
mixture in a mould in this dry condition and then exerting pressure upon it with
the intervention of felt c
or other material containing water or liquid which will
decompose the sulphate of ammonium forming lithanode containing in it crystals
or more or less pulverized grains of sulphate of magnesium and when the element
is removed from the mould these crystals or grains are removed or dissolved out
leaving the lithanode in the desired porous condition. This removal or dissolving
out may be effected by soaking in water or the crystals may be eliminated in the
forming" bath.
.
Although we have mentioned sulphate of ammonium and sulphate of magnesium
we do not limit ourselves to these salts as any other suitable matter or matters
can be used which will provide the necessary sulphuric acid for hardening the
element into lithanode and the inert crystals or grains which on elutriation or
dissolving out leave the lithanode in the requisite hard and porous condition.
For instance in place of sulphate of ammonium, sulphate of sodium or other
hydrated sulphate may be used and in place of the sulphate of magnesium there
may be used any other substance which will not be removed during the setting
operation but which is readily removed subsequently.
In lieu of employing the ammonium sulphate or the like in a dry condition as
aforesaid it may be used as a solution with which the felt or other material
employed in the pressing process is saturated or part of the ammonium sulphate
or the like may thus be used as a solution and part be mixed in a dry condition
with the other materials as aforesaid.
Or in place of using the compression with wetted felt or the like we may mix the
materials in a dry state as aforesaid and then introduce steam into the mould or
receptacle in which it is contained to remove the sulphate of ammonium or
the like.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed we declare that what
we claim is :-
1. In the manufacture of lithanode elements for secondary batteries the employ-
ment of an inert or comparatively inert material or salt which is afterwards
removed or dissolved out so as to leave the element in the condition of porous
lithanode substantially as herein before described.
2. In the manufacture of lithanode elements for secondary batteries the treatment
of litharge by means of sulphate of ammonium or equivalent matter which will
harden the litharge and of sulphate of magnesium or equivalent inert or
comparatively inert matter which will leave crystals or grains which can

page_text: subsequently be removed to leave the lithanode in a porous condition substantially
as hereinbefore described.
3. As a new article of manufacture an element for secondary batteries such as
can be produced as hereinbefore described.
Dated the 4th day of December 1893.
J. H. JOHNSON & Co.,
47, Lincoln's Inn Fields, London, Agents.