IMPROVEMENTS IN SECONDARY BATTERIES."
Year: 1881

page_text: LETTERS PATENT to Arthur Pillans Laurie, of Nairne Lodge, Duddingstone,
Edinburgh, North Britain, for an Invention of "IMPROVEMENTS IN SECONDARY
BATTERIES."
PROVISIONAL SPECIFICATION left by the said Arthur Pillans Laurie at
the Office of the Commissioners of Patents on the 4th October 1881.
ARTHUR PILLANS LAURIE, of Nairne Lodge, Duddingstone, Edinburgh, North
Britain. "LMPROVEMENTS IN SECONDARY BATTERIES."
My Invention relates to improvements upon that description of secondary battery
in respect of which I made application for Letters Patent dated the 28th June
1881, No. 2823.
According to my present Invention I employ two copper plates, or one plate of
zinc or other suitable metal (hereinafter designated plate No. 1), and one copper
plate (hereinafter designated plate No. 2), immersed in a solution of chlorido of zinc
or the chloride of any other metal I may find suitable, such for example, as chloride
of aluminum.
Plate No. 2 may with advantage be coated with copper in a fine state of
division and then wrapt round with linen, parchment, paper, or any other suitable
material.
When this battery is charged by means of an electric current zinc is deposited
on plate No. 1, and chlorine is set free at plate No. 2.
The chlorine immediately attacks the copper to form cuprous chloride.
If this cell is now used to supply a current, the chlorine of the chloride of zinc
attacks the deposited zinc and sets free zinc on plate No. 2.
The zinc set free on plate No. 2 combines with the chlorine of the cuprous
chloride to form chloride of zinc, leaving metallic copper.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Arthur Pillans Laurie in the Great Seal Patent Office on the
31st March 1882.
ARTHUR PILLANS LAURIE, of Nairne Lodge, Duddingstone, Edinburgh, North
Britain. "IMPROVEMENTS IN SECONDARY BATTERIES."
My Invention relates to secondary batteries wherein the essential feature is the
storing of chlorine for use as a source of electricity by combining it with copper to
form cuprous chloride, as hereinafter described.
According to my said Invention I employ two copper plates (which are
respectively referred to hereafter as plate No. and plate No. 2) immersed in a
solution of chloride of zinc.
If a current is passed through this cell from some external source of electricity,
the chloride of zinc is decomposed, zinc being deposited on the one copper
plate No. 1, and chlorine being separated at the other copper plate No. 2.
The chlorine separated at the copper plate No. 2 combines with the copper to
form cuprous chloride a white insoluble precipitate.
This is now a charged cell, and if the copper plates are connected by a wire an
electric current will flow through the wire until all the deposited zinc has been
reconverted into chloride of zinc. The zinc is converted into chlorido of zinc at
the expense of the cuprous chloride, chloride of zinc and metallic copper being
formed.
The cell is now in its original state, and on again passing an electric current
through the cell from an external source, zinc is again deposited and cuprous
chloride is formed, as before described.
It is necessary to keep the cuprous chloride formed in the cell while being
charged in contact with the copper plate, and to prevent it from diffusing through
the cell and reaching the zinc deposit, where it would be reduced, thus causing
waste. The substance found to be most suitable for preventing this diffusion of
the cuprous chloride is parchment paper. If a secondary cell, as above described,
is being charged by an external electric current, it rapidly opposes a very high
resistance to the charging current, this being due to a skin of cuprous chloride
formed on the plate No. 2. This increase of resistance may be retarded by
exposing a very large surface of copper to the action of the chlorine, and this
surface is best prepared by covering the copper plate with a paste of cuprous
chloride, and then reducing the cuprous chloride to metallic copper by means of a
zinc plate dipped into the chloride of zinc solution, and in metallic connection with
the copper plate.
A cell is therefore to be constructed as follows:-
A copper plate is coated with a paste of cuprous chloride and then wrapped in
parchment paper. It is then dipped into a solution of chloride of zinc along with
a zinc plate. The zinc and copper plates are then put in metallic connection, and
un electric current flows and continues flowing until all the cuprous chloride is
reduced to a mass of spongy copper. The zinc plate is then taken out of the liqnid
and replaced by a copper plate. The cell is now ready for charging.
The action of the chlorine on the spongy copper can be regulated by means of
copper gauze placed over the spongy copper, and in metallic connection with the
copper plate, that is to say, connected by solder.
There are in this way two surfaces of action, one on each side of the spongy
copper.
The cells may consist of vertical plates placed in a box, or of shallow copper
trays. These trays can be placed one inside another, and in this way a very
compact series of cells can be made.

page_text: The trays may with advantage be stamped with a shallow depression across
which wire gauze is fastened by solder or otherwise, which must be protected with
some varnish or by deposited copper.
The shallow depression is then filled with a paste of cuprous chloride, and
covered with parchment paper. The resistance to charging can be still further
lessened by the addition of small quantities of nitrate of zinc to the chloride of zinc
solution.
Plate No. 1 may be made of zinc or any other suitablo metal, though I prefer to
use copper.
Having now described and particularly ascertained the nature of my said
Invention, and the manner in which the same is or may be used or carried into
effect, I would observe in conclusion that what I consider to be novel and original,
and therefore claim as the Invention secured to me by the herein before in part
recited Letters Patent is,-
The hereinbefore described improvements in secondary batteries, the essential
feature of which is the storing of chlorine for use as a source of electricity by
combining it with copper to form cuprous chloride, substantially as hereinbefore
described.
In witness whereof, I, the said Arthur Pillans Laurie, have to this my
Specification, set my hand and seal, this Twenty eighth day of March, One
thousand eight hundred and eighty two.
A. P. LAURIE. (L.S.)