Improvements in or relating to Electrodes for Secondary Batteries.
Year: 1894

page_text: Date of Application, 29th Jan., 1894
Complete Specification Lett. 9th Oct., 1894-Accepted, 29th Jan., 1895
PROVISIONAL SPECIFICATION.
Improvements in or relating to Electrodes for Secondary Batteries.
I, MARCEL WUILLOT, of 32 Place de l'Industrie, Brussels in the Kingdom of
Belgium, Engineer, do hereby declare the nature of this invention to be as
follows:-
The new method of forming electrodes for accumulators is characterized by the
electrodes being submitted to the secondary action of electrolysis of an alkaline
bath, instead of an acid bath; this substitution having the effect of greatly
accelerating the formation of the Planté electrodes and of entirely preventing their
rapid disintegration when they are made after the Faure type.
The formation of the Planté plates in the sulphuric acid bath is slow. The
nitric acid pickling which has been proposed with a view to accelerate the process
as far as possible, exercises only a purely mechanical effect. It was intended to
promote the formation of spongy lead and oxidisation. The addition by mechanical
means of active substances which however are submitted with difficulty to trans-
formations of the kind, was a primary improvement effected by Faure.
But the electrodes formed in this manner have still the disadvantage of becoming
disintegrated after a comparatively short period of use, owing to the injurious
action inevitable with and inseparable from all acid baths. It is thus the reaction
of the acid bath which renders difficult all chemical transformation of lead plates
in the Planté process, preliminary to the electrical action; whereas there is no
difficulty in the way of a suitable chemical transformation of the lead if one
utilises immediately the secondary action of electrolysis of an alkaline instead of
an acid bath.
In connection with this an extremely favourable allotropic modification of the
lead can be effected by transforming it, either superficially and to a variable depth
or entirely, in one mass, into carbonate of lead, and by then immersing this latter,
as electrodes in an alkaline bath, wherein the second allotropic change is brought
about. On issuing from this second transformation the regenerated metallic lead
has regained a texture as close and consistent as that of the primitive lead itself,
while at the same time its initial capacity of polarisation has been considerably
augmented.
The electrodes obtained by this method of treatment which takes some hours are
absolutely fixed and stable, and practically of unlimited durability.
In detail the process of manufacturing these electrodes is as follows;-
The lead is subjected to the action of carbon dioxide whereby it is converted.
superficially or if desired entirely into carbonate of lead, commonly known as white
lead, whereof the nature and quality will depend upon the process adopted for the
transformation. The electrodes, thus allotropically modified at the surface, are
immersed in an alkaline bath (e.g. an ammoniacal solution) so that they may therein
as in a suitable medium, undergo the secondary actions of electrolysis. When
they have remained for a few hours only, exposed to electrolytic action, a complete
reconversion has taken place in the carbonate of lead; at the negative pole it, has
been transformed into spongy lead, while the result at the positive pole has been
a hard and uniformly wrinkled skin of oxide whereof the confused but brilliant
crystals defy the finger-nails, and impart to the transformed metal the perfect
closeness and consistency of the primitive lead, and the fixity and stability of

page_text: precipitated lead; and in this manner the electrodes are rendered proof against all
deterioration.
The alkaline bath exercises an analogous allotropic modification upon
electrodes made of salts of lead produced artificially or mechanically, as in the
Faure process; that is to say that the respective transformations of the salts at the
anode and at the cathode are effected to the entire exclusion of all sulphur com-
pounds, whereby the resulting metal is proof against all disintegration or deforma-
tion, in other words allowing a formation which is of absolute fixity and stability
and of unlimited durability.
Subordinately, the beneficial effects of the alkaline bath result in like advan-
tage with any electrodes of lead salts, artificially or otherwise obtained, in
the sense that the said bath plays with respect to them the part of a true
desulphurizing agent, hence all existing electrodes of this kind may be very easily
corrected or improved by the new process either when first made or while in use.
In consequence of the stability and fixity secured for such electrodes by means of
the alkaline bath they may be used without detriment as plates for accumulators
and for charge and discharge in the acid bath which has no deteriorating action
whatever on their surface by reason of the immunity conferred on them in such a
bath. The manufacture in this way of electrodes of carbonate of lead or other
salts of lead or the like creates certain bye-products which may find utilisation
in other industries and manufactures with which they are directly or indirectly
associated.
Dated this 29th day of January 1894.
W. P. THOMPSON & BOULT,
Agents for the Applicant.
Improvements in or relating to Electrodes for Secondary Batteries.
I, MARCEL WUILLOT of 32 Place de l'Industrie Brussels in the Kingdom of
Belgium, 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 :-
The object of this invention is to prevent the rapid wearing away of lead
electrodes in general, and of plates prepared by oxide coatings in particular, as
practised by Faure, so that the development of the disturbing element causing
the wear is prevented either by chemical transformation of the lead into lead salts
or by coating the plates thus formed. By this method the electrodes are formed
by electrolysis in an alkaline instead of an acid bath, thus accelerating the
formation of the Planté electrodes and preventing their rapid disintegration when
made after the Faure type. The formation of the Planté plates in the sulphuric
acid bath is slow, and the nitric acid pickling which has been proposed, with a view
to accelerate the process, exercises only a purely mechanical effect, it being intended
to promote oxidisation and the formation of spongy lead.
The electrodes formed after the Faure type become disintegrated after a
comparatively short period, owing to the injurious action inevitable with acid
baths. It is thus the reaction of the acid bath which renders all chemical trans-
formation of lead plates in the Planté process so difficult preliminary to the
electrical action; whereas there is no difficulty in the way of a suitable chemical
transformation of the lead if the action of electrolysis is employed in an alkaline
instead of an acid bath.
Ordinarily the disturbing element is introduced into the formation or electro-
lytic process by the oxides or salts giving rise to sulphate compounds, which now
only increase the internal resistance of accumulators but also after a very short

page_text: time cause the decomposition and falling away of the active substance. These
disadvantages can naturally be avoided either by eliminating such sulphates if
accidentally present or preferably preventing their formation, this latter as is stated
above may be accomplished by formation of the plates by electrolysis in an alkaline
bath.
This method offers great advantages by reason of its simplicity, and its
favourable action is explained by the fact that by electrolysis in an alkaline bath
(e.g. an ammoniacal solution) the acid and hydrogen combine at once with the
oxides or salts while the free ammonia remains neutral towards the lead derivatives
and no sulphur compounds are formed. Thus on the one hand we have spongy
lead and on the other only cellular compact and evenly wrinkled oxide, the texture
of which is as close and consistent as that of the primitive lead itself, while at the
same time its power of endurance in the battery has been considerably augmented,
so that electrodes are obtained after several hours treatment which are absolutely
stable and practically of unlimited durability.
Therefore if ordinary lead is either in part or wholly transformed by carbonic
acid into carbonate of lead and subsequently passed through the above described
process, the entire carbonate is transformed, at the negative pole into spongy lead,
and at the positive pole into hard wrinkled oxide the employment of which largely
increases the capacity of secondary batteries.
Similar advantages may be obtained by treatment of lead oxide electrodes,
(made by mechanical process after Faure's method) in alkaline baths; as a
transformation of the salts as above described is thereby effected and the formation
of sulphates avoided.
While as above mentioned the ammonia of the alkaline bath is neutral towards
the lead derivatives, it combines with any sulphur compounds present in the
electrodes, separating them out as sulphates of ammonia. Thus electrodes formed
under the old process may by these means be regenerated and transformed into
absolutely stable and durable electrodes perfectly protected against wear and
decay.
Having now particularly described and ascertained the nature of the said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is ;-
1. The process for the production of electrodes formed throughout of lead and
lead salts or oxides for secondary batteries whereby all sulphate formations are
prevented and all sulphur compounds present are removed the original lead being
transformed into pure oxide and spongy lead respectively by the formation of such
electrodes by electrolysis in an alkaline bath substantially as described.
2. Producing electrodes for secondary batteries by the utilisation of electrolysis
in an alkaline bath by means of electrodes of lead or of salts of lead substantially as
described.
3. In the formation of electrodes for secondary batteries the use of electrodes
of lead converted superficially or entirely into lead carbonate substantially as
described.
4. In the formation of electrodes for secondary batteries the use of electrodes of
salt or salts of lead artificially prepared or entirely made of salt or salts of lead
produced mechanically chemically electro-chemically galvanically by adhesion
or by any other mode of formation substantially as described.
5. The process of desulphatisation of electrodes for secondary batteries either in
the course of their manufacture or after use substantially as described.
Dated this 9th day of October 1894.
W. P. THOMPSON & BOULT,
Agents for the Applicant.