IMPROVEMENTS IN SECONDARY RATTERIES
Year: 1882

page_text: LETTERS PATENT to Charles Henry Cathcart of Cressingham Grove Sutton
in the County of Surrey for an Invention of "IMPROVEMENTS IN SECONDARY
RATTERIES"
PROVISIONAL SPECIFICATION left by the said Charles Henry Cathcart at
the Office of the Commissioners of Patents on the 1st July 1882.
CHARLES HENRY CATHCART of Cressingham Grove Sutton in the County of
Surrey "IMPROVEMENTS IN SECONDARY BATTERIES"
My improvements relate to the construction of secondary battery described in a
Provisional Specification filed by me and C. B. G. Cole on the 2nd of May 1882
No. 2068.
My present improvements have for their object to prevent as far as possible
the polarization of the positive plates of such secondary batteries, which causes a
constant waste of electrical energy; to allow of free circulation of the liquid in
the battery; and to secure a firm deposit of metal on the positive plate when the
cell is fully charged.
This is accomplished by giving to the positive or zinc plates of such batteries a
very large extent of surface within a small compass by using perforated zinc bent
into various shapes. The perforation of the zinc allows of the free circulation of
the liquid, and the metallic deposition takes place not only on the outer surfaces
but also on the inner surfaces of the plates (brought about by the configurations
of the same).
The improved form of secondary battery is constructed as follows: The positive
clement consists of a plate or plates of perforated zinc, as described above, covered
with a coating of electrolytically deposited pure zinc, the whole being finally
amalgamated with mercury.
The negative element consists of a plate or plates of (1) lead amalgamated with
mercury and oxidised to a considerable depth by electrolytic action, or (2) lead or
carbon coated mechanically with one or more of the oxides of lead; if plates of
this description be used the battery will require "forming" by passing an electric
current through the cell in the charging direction for some days. In either case it

page_text: is desirable that the lead plates should be scratched or otherwise roughened, and
that some fabric be used to prevent the oxide from falling away from the plate.
The positive and negative plates as above described (arranged alternately if
there be more than two) being held in position by a framework of ebonite or other
suitable material and metallically connected with their respective terminals or
binding screws are immersed in a nearly saturated solution of sulphate of zinc in
water acidified with sulphuric acid and containing sulphate of soda, sulphate of
ammonia, or other similar salts or mixtures of the same.
It will be understood that the shape and size of the cell are of but minor
importance, and that any number of zinc and lead (or carbon) plates may be
employed therein.
It will also be seen that no particular form need be assigned to the positive or
zinc plate of this secondary battery, as the object of the Invention is to utilise a
large extent of surface, thereby securing a strongly adherent deposit of metal when
the battery is fully charged, at the same time avoiding polarization while the
operation of charging is going on and allowing free circulation of the liquid owing
to the perforation of the zinc plates, and therefore any configuration of the zinc
plates which produces these results comes within the limits of this invention.
A convenient arrangement however consists in bending the zinc into corrugations
which are brought closely one against the other.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Charles Henry Cathcart in the Great Seal Patent Office on
the 30th December 1882.
CHARLES HENRY CATHCART of Oressingham Grove, Sutton in the County of
Surrey IMPROVEMENTS IN SECONDARY BATTERIES'
My Invention relates to improvements in secondary batteries of the kind
described in the Specification to Letters Patent granted to me and C. B. G. Cole
on the 2nd May 1882, No. 2068.
.
My improvements have for their object to prevent as far as possible the
polarization of the positive or zinc plates of such secondary batteries during the
process of charging; to allow of free circulation of the liquid in the battery, and
to secure a firm deposit of metal on the positive or zinc plate when the cell is
charged.
This is accomplished by giving to the positive or zinc plates of such batteries a
very large extent of surface within a small compass by using perforated zinc,
corrugated or bent into various shapes. The perforation of the zinc allows of the
free circulation of the liquid and the metallic deposition takes place not only on the
outwardly exposed surfaces but also on the surfaces inside the curvatures of the
plates.
The improved form of secondary battery is constructed as follows:-The
positive element consists of a plate or plates of perforated zinc bent or corrugated
as described above. These are in the first place well amalgamated with mercury
and are then covered with a coating of electrolytically deposited pure zinc, the
whole being finally again amalgamated with mercury. The negative element
consists of a plate or plates, which may be of lead amalgamated with mercury and
oxidised to a considerable depth by electrolytic action, or may be of lead or carbon
coated mechanically with one or more of the oxides of lead; if plates of this
latter description be used, the battery will require "forming" by passing an electric
current through the cell in the charging direction for some days. It is preferred
that the plates be scratched or otherwise roughened on the surface and that they
be wrapped in some fabric such as flannel to prevent the oxide from falling away
from the pintes. The positive and negative plates as above described arranged
alternately being held in position by a framework of ebonite or other suitable
insulating material and metallically connected with their respective terminals
or binding. screws, are immersed in a nearly saturated aqueous solution of pure
sulphate of zinc acidulated by sulphuric acid. The shape, size and number of the
cells may be varied as desired, as well as the character and form of the flexures
given to the positive or zinc plates. A convenient arrangement is to bend the zinc
into corrugations brought closely one against the other.
Having thus described the nature of my invention and in what manner the same
is to be performed, I claim :-
The use in secondary batteries of positive plates of perforated zinc, bent or
corrugated so as to present extended surface substantially.as, and for the purposes
herein set forth.
In witness whereof I the said Charles Henry Cathcart have hereunto set
my hand and seal this Thirtieth day of December in the year of our Lord,
one thousand sight hundred end eighty-two