IMPROVEMENTS Kent IN SECONDARY BATTERIES, ALSO APPLICABLE TO ORDINARY GALVANIC BATTERIES,
Year: 1882

page_text: PROVISIONAL SPECIFICATION left by Arnold Frank Hills at the Office of
the Commissioners of Patents on the 24th October 1882.
"IMPROVEMENTS
ARNOLD FRANK HILLS of Penshurst in the County of Kent
IN SECONDARY BATTERIES, ALSO APPLICABLE TO ORDINARY GALVANIC BATTERIES,
The chief desiderata in Secondary or storage batteries are a large extent of
surface and perfect contact of the plates with the fluid in which they are immersed ;
and with a view to obtain these advantages to the greatest degree possible the
tendency of most recent improvements on this class of Battery has been to obtain
the lead used to form the plates in the highest possible state of subdivision.
Experience has further proved that during the process of charging, or in other
words "forming" the battery the lead becomes oxydised in a high and a low
degree respectively and with a view to assist the process of oxydation the metallic
lead plates have been coated with oxide of lead (red lead) in the form of paint.
This coating of oxide of lead has however a deleterious effect, inasmuch as it
causes in combination with the metallic lead a considerable amount of local action,
which may be said to be the weak point in most of the existing secondary
batteries.
Now the object of this invention is to obtain the greatest amount of surface
contact, and thereby increased capacity for storing electrical energy; at the same
time avoiding the inconvenience of the local action referred to above.
To this end I employ in making my improved batteries oxide of lead in powder.
This oxide presents the lead, not only in the highest state of subdivision, but also
already oxidised or in the best possible chemical condition for the purpose required..
Lead oxide forms a middle term in that series of oxydation which is necessary
for forming the maximum and minimum points of electrical storage that is to say
it only requires to be deoxydised or reduced on the one hand to form the negative
pole of the battery, and to be per-oxydised on the other hand to form the positive
pole of the battery, and is therefore in the best condition obtainable for alternate
oxydation and reduction at the positive and negative poles.
Further the success or failure of the battery and the presence or absence of local
action depends materially on the purity of the metal employed and such purity is
ensured by the use of the oxide.

page_text: One advantage immediately obvious from this principle is that the process of
storing can be conducted continuously in one direction, thus avoiding the loss
of time and energy involved in the constant reversals and intervals of rest required
in ordinary accumulators.
In constructing a storage battery I take a suitable trough, say of wood, and
divide it into a convenient number of cells. In each cell Ï place at a suitable
distance one from the other two perforated lead plates. The spaces between the
lead plates and the walls of the cells I fill up with lead oxide; and between the lead
plates I place a suitable electrolyte. The external faces of the lead plates may be
insulated with any suitable insulating substance to induce the generation of the
oxygen and Hydrogen at the alternate poles inside, and therefore in close contact
with the mass of oxide.
The negative partition of the cell may with advantage be made considerably
larger than the positive, probably in the proportion of 2 to 1. When formed by
the passage of the current there is nothing in the battery but a high per-oxide of
lead opposed to a protoxide of lead, always excepting the two conducting lead.
plates which should be as thin as is consistent with necessary strength, but the
mass of oxide at either pole being far larger in proportion than the mass of the
plates, the local discharge at the poles when the circuit is broken is practically
inappreciable, and thus the defect of local action is eliminated.
If it is desired to form the cells with plates in order to reduce the internal
resistance of the cell, I take sheets of lead foil properly perforated and fold them
into sacks. These sacks I fill with oxide of lead and use the top fold of the sack
for the necessary terminal, still observing the proportion already referred to
between the positive and negative poles.
The rapidity of oxydation may be further increased by mixing a small
_percentage of sulphur with the oxide of lead, but only at the positive pole and
by adding a percentage of alcohol or ammonia to the electrolyte.
The oxides of other metals may be employed instead of lead such as the oxides
of Zinc, Iron, Copper or aluminium. In such a case the electrolyte employed
must be one that does not attack the metal used, as for instance hydrochloric
acid, chromic acid, a solution of caustic soda or potash. Or metals removed
from one another in the electro chemical scale may be employed namely:
lead Oxide and Copper, with an electrolyte of sulphate of copper; or zinc and
iron or zinc and copper with a suitable electrolyte. Apart from commercial
reasons the combination of the metals is unimportant, provided that the principle
is kept in view of using the oxides of the metals where possible at either pole.
In constructing an ordinary galvanic battery according to the principles above
explained I take an oxide of zinc, lead, or iron, and oppose it in a suitable
electrolyto such as a mixed solution of nitric and sulphuric acid, or a simple
solution of nitric or sulphuric acid, or per-oxide of hydrogen, or a solution of one
of the alkalies, to a negative pole of carbon, or platinum.
Then as already explained the oxide is advanced along the path of oxydation,
and a direct chemical advantage is gained, and further if proper precautions are
taken for preventing the polarization of the negative pole by electrolytic
hydrogen eg, by placing it in contact with nitric acid, or where a lead negative
pole is employed by allowing it to be reduced, and provided also that the
electrolyte is present in sufficient quantities, the battery may run on constantly
until the entire positive pole is exhausted, when it can again be restored to its
original condition, by passing a current through it from the negative to the
positive poles.