Improvements in Secondary Galvanic Batteries or Accumulators.
Year: 1899

page_text: PROVISIONAL SPECIFICATION.
Improvements in Secondary Galvanic Batteries or Accumulators.
We, RICHARD NORMAN LUCAS, of Spring Cottage, Byfleet, Surrey, and ERNEST
SANFORD NEW, of the Voltage, Woking, Surrey, Electricians, do hereby declare
the nature of this invention to be as follows:-
Our invention has for its object certain improvements in secondary batteries
and namely in the negative plate or plates employed therein. It further has
special reference to that class of negative plate in which the active material is
deposited electrolytically from solution during the periods of formation or
charge upon a grid or support of conducting material unacted upon by the
acid electrolyte which is employed in the battery.
The material which we prefer to employ is copper wire woven into the form of
moderately fine gauze. But we may also use perforated sheets of the same
metal as also sheets or gauze of metals or alloys which are not readily acted upon
Ly sulphuric acid but form alloys with mercury. We prefer to employ a double
sheet of this gauze and this may either form a single flat sheet or plate or may be
bent in and out zig-zag fashion in the known manner or over and under between
the position plates of the battery. We then deal with the sheet or plate of
copper gauze as follows:-
To a suitable part of the gauze grid or support is connected a leaden lug of
sufficient length of project well above the surface of the electrolyte when the
negative is in position in the battery. This projecting lug forms or is connected
to the negative terminal of the battery. It is secured to the gauze so as to form
a good mechanical and electrical connection with each of its longest wires either
by lead-burning, melting, rivetting, dressing, or by hydraulic pressure or a com-
bination of these methods.
This construction secures an equable distribution of current to and from
every portion of the gauze, grid or support both during charge and discharge.
We employ a leaden lug or connection applied in this manner because we have
found that if the copper itself be brought up to form a connection it becomes
attacked and ultimately destroyed in very short time at the surface of the
electrolyte.
Having in this manner provided our plate or sheet of gauze with a conducting
connection we proceed to the process or treatment forming the second character-
istic of our invention that is to say we immerse it in a dilute acid capable of
thoroughly etching or penetrating into the substance of the copper. Hydrochliic acid
or dilute aqua regia may be employed for this purpose. A mixture which we have
found to give a good result is one of one part of nitric acid to about five parts
of water by volume. The sheet or plate of gauze is immersed in this mixture
until a copious evolution of gas takes place and for some minutes after that,
when it is withdrawn from the dilute acid and examined if found to be thoroughly
well etched and attacked it is subjected to the next step in the treatment. If
it does not show distinct signs of being attacked it may be replaced in the dilute

page_text: acid until it does. When thoroughly attacked it is withdrawn as stated and
subjected to the next step in the process. This consists of insertion into a
strong acid solution of a salt of mercury of which we prefer the nitrate. The
plate is allowed to remain in this solution till it is well coated with a white
silvery deposit of metallic mercury. It is then removed, washed, and immersed
for some time in metallic mercury in which it is agitated or the mercury may be
rubbed in say with a cloth.
A variation of this process consists in employing a neutral solution of a
mercury salt for silvering in which case however the etching in the acid bath
must be carried further. If on the other hand the silvering bath be made
strongly acid the etching in the first acid bath may be omitted as it can be thus
efficiently performed in the silvering bath, the, first acid bath being in that case
used merely or mainly to clean the copper.
The negative is then assembled with an ordinary positive plate or plates or
with dummy plates and electrolytically coated with the active material which
may be and preferably is metallic zine deposited from a pure solution of the
sulphate but other metals such as cadmium may be employed.
When treated by our process as above described the metallic grid becomes
so interpenetrated with mercury as practically to form an alloy with that metai.
Indeed if broken up and examined the mercury will be found to have penetrated
into the very centre of the metal and the whole will be found to present a silvery
white appearance.
To the above described method of preparing and connecting the supporting
grid we attribute the success of our improved negative element.
Dated this 6th day of September 1899.
RICHARD NORMAN LUCAS,
Agent for the Applicants.
Improvements in Secondary Galvanic Batteries or Accumulators.
We, RICHARD NORMAN LUCAS, of Spring Cottage, Byfleet, in the County of
Surrey, and ERNEST SANFORD NEW, of The Voltage, Woking, in the County of
Surrey, Electricians, 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:-
Our invention has for its object certain improvements in secondary batteries
and namely in the negative plate or plates employed therein. It further has
special reference to that class of negative plate in which the active material is
deposited electrolytically from solution during the periods of formation or
charge upon a grid or support of conducting material unacted upon by the
acid electrolyte which is employed in the battery.
The material which we prefer to employ is copper wire woven into the form
of moderately fine gauze. But we may also use sheets of the same metal per-
forated in such a way as to give an equivalent surface. The most successful
results have been obtained with high grade commercial copper but we have
found that alloys of copper with zinc and tin may be used, provided that the
alloy contains a large proportion of copper. We prefer to employ a double sheet
of this gauze and this may either formed a single flat sheet or plate or may be
bent in and out zig-zag fashion in the known manner or over and under between
the positive plates of the battery. We deal with the sheet or plate of copper
gauze as follows:-

page_text: To a suitable part of the gauze grid or support is connected a leaden lug of
sufficient length of project well above the surface of the electrolyte when the
negative is in position in the battery. This projecting lug forms or is connected
to the negative terminal of the battery. It is secured to the gauze so as to form
a good mechanical and electrical connection with each of its longest wires either
by lead-burning, melting, rivetting, dressing, or by hydraulic pressure or a com-
bination of these methods.
In practice we have found that a reliable connection may be obtained by
laying the edge of the copper gauze on a suitable leaden bar or lug and melting
down lead strip on to the copper by means of a hydrogen flame, until the melted
lead strip combines homogeneously with the leaden lug thus entirely enclosing
the copper.
This construction secures an equable distribution of current to and from
every portion of the gauze, grid or support both during charge and discharge.
We employ a leaden lug or connection applied in this manner because we have
found that if the copper itself be brought up to form a connection it becomes
attacked and ultimately destroyed in a very short time at the surface of the
electrolyte.
Having in this manner provided our plate or sheet of gauze with a conducting
connection we proceed to the process or treatment forming the second characteristic
cf our invention that is to say we immerse it in a dilute acid capable of thoroughly
etching or penetrating into the substance of the copper. Hydrochloric acid
or dilute aqua regia may be employed for this purpose. A mixture which we have
found to give a good result is one of one part of nitric acid to about five parts
of water by volume. The sheet or plate of gauze is immersed in this mixture
until a copious evolution of gas takes place and for some minutes after that.
when it is withdrawn from the dilute acid and examined if found to be thoroughly
well etched and attacked it is subjected to the next step in the treatment. If
it does not show distinct signs of being attacked it may be replaced in the dilute
acid until it does. When thoroughly attacked it is withdrawn as stated and
subjected to the next step in the process. This consists of insertion into a
strong acid solution of a salt of mercury of which we prefer the nitrate. The
plate is allowed to remain in this solution till it is well coated with a white
silvery deposit of metallic mercury. It is then removed, washed, and immersed
for some time in metallic mercury in which it is agitated or the mercury may be
rubbed in say with a cloth.
A variation of this process consists in employing a neutral solution of a
mercury salt for silvering in which case however the etching in the acid bath
must be carried further. If on the other hand the silvering bath be made
strongly acid the etching in the first acid bath may be omitted as it can be thus
efficiently performed in the silvering bath, the first acid bath being in that case
used merely or mainly to clean the copper.
The negative is then assembled with an ordinary positive plate or plates or
with dummy plates and electrolytically coated with the active material which is
metallic zinc deposited from a pure solution of the sulphate. It is advisable
that the amount of zinc so deposited shall be in excess of the amount which
is dissolved during a normal discharge. In practice we prefer to deposit twice
the amount so dissolved.
When treated by our process as above described the metallic grid becomes
so interpenetrated with mercury as practically to form an alloy with that metal.
Indeed if broken up and examined the mercury will be found to have penetrated
into the very centre of the metal and the whole will be found to present a silvery
white appearance.
We are aware that copper gauze superficially amalgamated with mercury and
coated electrolytically with zinc has been used in secondary batteries: but it is
to the special process and method of treating the said inactive support and also
to the application and affixture thereto of the conducting leaden connection that

page_text: we attribute the success of our invention and in particular the avoidance of
solution of copper in the electrolyte which has hitherto been a difficulty in this
class of battery.
Having now particularly described and ascertained the nature of our said
invention and in what manner the same is to be performed, we declare that
what we claim is:-
1. The process of formation of negative electrodes for secondary batteries con-
sisting of first subjecting a gauze or other equivalent plate of copper or equivalent
metal to the action of an acid solvent and a soluble mercury salt so as to
produce a thorough interpenetration of mercury, and the subsequent electrolytic
deposition of zinc thereon for the purposes described.
2. A negative electrode for secondary batteries consisting of gauze or perforated
sheet of copper or equivalent material interpenetrated with mercury and electro-
lytically coated with zinc, and having a leaden lug so connected thereto as to be
in complete mechanical and electrical contact therewith and to be the sole part
of the support of the negative element which passes above the battery fluid,
substantially as described.
Natal this Sixth day of Tune 1000
RICHARD NORMAN LUCAS,
Agent for Applicants.