Improvements in the Manufacture of Electrodes for Primary and Secondary Batteries.
Year: 1890

page_text: Date of Application, 19th Aug., 1890-Accepted, 27th Sept., 1890
COMPLETE SPECIFICATION.
Improvements in the Manufacture of Electrodes for Primary and
Secondary Batteries.
I, DAVID PEPPER, Jr., of 1827 Spruce Street, in the City and County of
Philadelphia, State of Pennsylvania, United States of America, Electrician, do hereby
declare the nature of my invention, and in what manner the same is to be
performed, to be particularly described and ascertained in and by the following
statement:-
per
The object of my invention is to produce electrodes fitted for use in primary or
secondary batteries and which can be produced both rapidly and cheaply. This I
accomplish in the following way, viz.: I take a salt or oxide of lead, preferably an
oxide, and of the oxides, preferably litharge. The salt or oxide of lead must be in a
finely divided condition, preferably a powder, and with this salt or oxide I mix a
fusible and soluble salt of an alkaline metal or earth such as soda, potash, ammonia,
or magnesia; or a mixture of two or more of these salts. The proportion of the
last-named salts to the salt or oxide of lead should be in the neighbourhood of
twelve cent. in the case of nitrate of soda about one to eight, or about twelve per
cent. I have found to be best. This percentage I believe will be about as low as can
be conveniently and advantageously used with my process. The porosity of the plate
is increased as the percentage of the fusible and soluble salt is increased. The fusible
salts mixed with the salt or oxide of lead should also of course be finely divided to
enable the mixture to be effected. Having mixed the salts or salts and oxide
thoroughly I place the mixture in a mould and heat it to a temperature which will
fuse the fusible and soluble salts, then permit it to cool and remove it from the
mould in the form of a strong coherent plate, the salt or oxide of lead being
thoroughly cemented by the fusible salt in admixture with it and which, in many
cases, also enters into chemical union with the lead salt or oxide. The plates thus
made are converted into electrodes suitable for use in a battery by using them as
the anodes or cathodes in a suitable electrolyte such as dilute sulphuric acid. When
used as the anode of a primary or secondary battery the salt or oxide of lead is
oxidized to peroxide of lead or a salt or oxide easily.converted into peroxide and
the fusible soluble salt dissolved out and eliminated from the plate during its con-
version. When used as the cathode of the battery the salt or oxide of lead is
converted into metallic lead and the fusible soluble salt dissolved and eliminated in
the same way. In both cases the plates are left in a thoroughly, porous condition and
yet strong and coherent.
Where my process is applied for the manufacture of the positive plate the soluble
and fusible salt or salts used in admixture with the salt, salts or oxide of lead
should preferably be such as will have an oxidizing effect; when heated thus I prefer
to use in the manufacture of such plates a mixture of nitrate of soda eight parts, and
one or two parts of a salt or salts which have strong oxidizing properties when heated
in admixture with the salt or oxide of lead and the fusible salt; such salts are the
chlorates per chlorates, manganates and per manganates of soda, or potash or ammonia.
I prefer to use chlorate of potash. These salts will act upon the salt or oxide of
lead when they are heated to fusion and during this part of the process begin the con-
version of the salt or oxide of lead into a peroxide forming a mixture of red lead and
peroxide, and during the subsequent treatment in the bath of the battery the sulphuric
acid of the electrolyte acting on the nitrate of soda converts it into free nitric acid
and sulphate of soda; the nitric acid uniting with the lead forming nitrate of lead
which salt is easily convertible in the peroxide of lead and the sulphate of soda of
course dissolving readily. The electrolyte also acts upon the chlorate of potash or
similar salt remaining in the mixture decomposing it into oxygen, free chlorine gas,

page_text: and sulphate of potash, the free gas acting as a powerful oxidizing agent on the salt
of lead and the sulphate of potash dissolving out from the mass; where a manganate
is used the electrolyte acting upon it liberates oxygen gas which acts immediately
upon the lead salt or oxide.
When manufacturing negative plates for batteries I prefer to use a soluble and
fusible salt which will have a reducing action upon the salt or oxide of lead and can,
if desired, and without injury to the plate, mix with the salt an additional reducing
agent such as carbon, a compound easily converted into carbon, or a small proportion
of an acetate or oxalate preferably of lead. The salts which I would prefer for use in
the manufacture of the negative plates are the nitrates of soda or potash in admixture
with sulphates or chlorides of magnesia, potash, soda, and ammonia, all of which have
a reducing action on the salt or oxide of lead. The nitrate of soda can, however, be
used alone with good results and economically in the manufacture of the negative as
well as the positive plates.
The coherent mixture effected by my above-described treatment of the mixed
powdered salts or salts and oxides in the inould is amorphous and the salt or oxide of
lead preferably never heated to the point of fusion.
The plates made by my method may be provided with connections in any suitable
way.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is:
First: The method of manufacturing plates for conversion into electrodes which
consists in mixing with an oxide or a salt of lead, a fusible and soluble salt, placing
the mixture in a mould, and heating it to the point of fusion of the fusible and
soluble salt.
Second As a new article of manufacture a plate suitable for conversion into
an electrode composed of an amorphous mass of a lead oxide or salt cemented
together by the fusion of a fusible and soluble salt.
Third: The method of manufacturing plates suitable for conversion into positive
electrodes which consists in mixing litharge with a fusible soluble and oxidizing salt
or mixture of salts, placing the mixture in a mould and heating it to the point of
fusion of the fusible and soluble salt.
Dated this 10th dor of August 1800.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, Agents for the Applicant.