Improvements in Dry Batteries.
Year: 1893

page_text: Date of Application, 27th Dec., 1893-Accepted, 17th Feb., 1894
Improvements in Dry Batteries.
I, HARRY TORREY JOHNSON, Electrician, of 36 Cortlandt Street, in the City,
County and State of New York, United States of America, 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 :--
My invention relates to that class of primary batteries or cells which are
peculiarly adapted for open circuit work, and which are popularly known as dry
batteries. In such batteries the negative electrode, usually formed of retort
carbon, is surrounded with a semi-solid depolarizing-conducting mixture. The
depolarizing layer of the cell, which is ordinarily in contact with the negative
electrode, sometimes consists of granulated or powdered carbon, but is more often
formed of a mixture of carbon and peroxide of manganese in a comminuted or
powdered condition.
The object of my invention is to provide for a more intimate and tenacious
contact between the surface of the negative electrode and the surrounding substance,
whereby such contact will be prevented from becoming impaired sufficiently to
create an excessive internal resistance in the cell; and to this end my invention
consists of a galvanic battery of the character described having a negative electrode
forined with an uneven contact surface, which will operate to bind or wedge the
electrode in position, and to reduce the tendency of the surrounding mass to fall
away from the surface of the electrode, either through shrinkage or settling of the
mass under ordinary conditions of use, or through careless handling of the cell in
transportation or setting up.
In the accompanying drawings
Figure 1 is a central sectional elevation of a galvanic cell embodying my
invention;
Fig. 2 is a view of the negative electrode in elevation ;
Fig. 3 is a horizontal section on the line 3-3 (Fig. 1);
Fig. 4 is a view in elevation showing a modification in the construction of the
negative electrode ;
Fig. 5 is a horizontal section thereof on the line 5-5 (Fig. 4);
Fig. 6 is a view in elevation showing another modification in the construction of
the negative electrode, and
Fig. 7 is a horizontal section thereof on the line 7-7 (Fig. 6).
Similar letters and figures of reference are employed to designate corresponding
parts in all the views.
In the specific form of battery shown in the drawings, A designates the negative
electrode, which in the construction shown is formed of hard or retort carbon.
Surrounding the electrode A is a layer B of finely divided carbon and manganese
mixed in approximately equal quantities, and packed tightly around the electrode A,
either by tamping or otherwise. Surrounding and enclosing the layer B is a cup or
diaphragm C of porous substance. I have derived the best results by constructing
the cup or diaphragm C of heavy absorbent paper, such as blotting paper; but
where said cup or diaphragm is employed, other materials may be employed
therefor. Around the cup or diaphragm C lies a layer D of semi-solid substance
containing an exciting salt such as sal ammoniac. The layer D is preferably
formed by dissolving the sal ammoniac in water and mixing sufficient plaster of Paris
therewith to cause the mass to set and form a semi-solid substance when poured
into place. The zinc cup E serves both as a containing vessel and a positive
Im...oll

page_text: electrode for the cell. The open ends of the cups C and E are covered with the
layers of bitumen cand e which form an hermetic seal for the cell, and the electrodes
are provided with the usual binding screws.
The negative electrode A instead of having all the surfaces thereof, which contact
with the depolarizing layer B, flat and comparatively smooth, as they have heretofore
been constructed, has one or more of its surfaces, preferably both of its widest sides,
formed with an uneven surface, as shown. This uneven contact surface may be
produced by forming transverse parallel grooves or depressions therein extending
across the face of the carbon, as shown in Fig. 1 as well as in many other ways, as
for instance by forming knobs or projections thereon as shown in Figs. 6 and 7 .or
by perforating, slotting or recessing the electrode, as shown in Figs. 4 and 5. 1
prefer the use of the transverse grooves, ridges or corrugations however, as they
tend to hold the carbon more firmly in place, and also increase the area of the
conducting surface of the electrode.
The advantages of my improved construction, which is applicable to any of the
different makes of dry batteries on the market, are obvious. In a cell constructed
with a smooth electrode such as heretofore used, the falling away of the substance
surrounding the electrode, which is very apt to occur, either through the settling
of the mass, or through its shrinkage caused by the evaporation of the moisture
which it contains, or through careless handling in transportation or setting up, will
by destroying the contact between the electrode and such substance, greatly
increase the internal resistance of the cell and impair its efficiency; but with my
improved electrode, having an uneven contact surface, if the surrounding mass
settles or shrinks, it will still remain in contact with the electrode, and the
wedging action of the mass on the protuberances or depressions of the electrode
will hold the electrode firmly in place and prevent its accidental displacement.
Another serious defect which is frequently developed in dry batteries as heretofore
constructed is the slight resistance which the mass surrounding the negative
electrode presents to the withdrawal of the carbon from the cell. This is due to
the fact that the smooth surface of an electrode of the old form presents but slight,
if any, obstacle to its vertical movement in the surrounding substance, and it often
happens, particularly where the hermetic seal has been cracked or loosened, that if
a cell containing a smooth electrode be litted by the electrode which presents a
convenient handle for that purpose, the same will be drawn bodily out of the cell,
and the cell will be completely ruined, because it is impossible to replace the
electrode properly without making the cell entirely over again; but with my
improved electrode, its uneven surface causes it to be wedged tightly in place by
the packing of the mass B around it, and even if the seal be entirely destroyed,
the electrode will be so firmly gripped thereby that it cannot be accidentally
displaced. It will also be observed that these advantages are attained without any
substantial increase in the cost of the cell, and also without complicating its
construction or increasing the number of its parts.
I use the term uneven surface herein to denote a surface which is provided with
projections, depressions, perforations or recesses, either in regular or irregular
arrangement.
Having now particularly described and ascertained the nature of this said inven
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. In a dry battery the combination of a containing cup or cylinder forming the
positive electrode a semi-solid filling within the same and a negative electrode
having an uneven surface embedded in said filling substantially as shown and
described.
2. In a dry battery the combination of a cup shaped positive electrode a porous
diaphragm or cup within the same a semi-solid mixture containing an excitant
between the same and said positive electrode a negative electrode surrounded by
said porous diaphragm and having an uneven surface, and a semi-solid filling

page_text: between the surface of the electrode and said diaphragm substantially as shown
and described.
3. Roughening perforating or otherwise making irregular the surface of the
negative electrode of a dry battery for the purpose of increasing the adhesion
between the said electrode and the depolarizing material.
Dated this 27th day of December 1893.
W. P. THOMPSON & BOULT,
Agents for the Applicant.