Electrical contact outlet for anodes

Electrical contact outlet for an anode sheet of a lithium generator with polymer electrolyte, consisting of one or more multilayer electrochemical cells. The cell comprises at least one lithium base sheet having a thickness between about 1 and 50 microns to constitute the anode and its collector and additionally includes a cathode and its collector as well as the polymer electrolyte. A lateral end of the anode sheet extends beyond corresponding ends of the cathode and the collector to constitute a projecting zone. A metallic layer consisting of at least one rigid metal which is compatible with lithium is in electrical contact with the lateral end of the anode sheet but without electronic contact with the other components of the cell. The metallic layer constitutes the external terminal of the generator when the latter is in non-finished condition. According to a variant, a conductive and cohesive intermediate metallic zone, which consists of lithium or lithium rich ductile alloys is in intimate contact with the lateral end of the anode sheet and the metallic layer mentioned above is therefore in electrical contact with the lateral end of the anode sheet by means of the intermediate zone of lithium. Generators provided with such contact outlet as well as a process for the preparation of these contact outlets are described.

BACKGROUND OF THE INVENTION 
(a) Field of the Invention 
The invention describes devices and processes including lateral electrical 
contact outlets on lithium sheets which are used as anodes in lithium 
generators consisting of at least one. multilayer assembly of thin 
electrode films and polymer electrolytes in wound or stacked form. The 
patent describes materials and devices including a contact outlet on thin 
sheets of lithium in the vicinity of the plastic materials of the 
generator as well as procedures for producing these devices. The claimed 
lateral contact outlet devices are particularly suitable for all solid 
polymer electrolyte generators because they are very slightly resistive, 
they are adapted to the chemical reactivity of lithium and its alloys and 
are capable of ensuring an efficient heat exchange between the generator 
and its external casing. In one of the preferred devices, the electrical 
contact on the thin lithium sheets is obtained with a compatible metal, 
preferably copper, iron, nickel of alloys thereof, directly applied on 
lithium. A variant of this device consists in first providing an 
intermediate metallic layer of a lithium base metal or low melting lithium 
alloys which is applied in the form of a compact deposit at the end of the 
sheets of lithium. This deposit, called intermediate metallic layer, 
thereafter enables to obtain a second electrical contact, on its other 
face, with an inert and rigid metal, which is compatible with lithium, and 
is capable of maintaining the quality of the electrical contact between 
the anode of the generator and the external casing in spite of a possible 
superficial oxidation of lithium or its alloys. 
The application of a metal such as copper which is in direct contact with 
lithium enables, whenever possible, to use the generator in dry air and 
additionally contributes to facilitate a thermic transfer between the 
latter and its external casing. The alternative which consists in using a 
metal such as lithium or its low melting alloys to provide an intermediate 
metallic layer, solves the problem of chemical reactivity with the lithium 
anode, facilitates the self-welding and cohesion of the deposit and 
ensures some deformability of the contact zone during thermic and 
electrochemical cycles of the generator. On the other hand, the low 
melting point of the filler metal facilitates its application on the edges 
of thin lithium films, even at a short distance from the other plastic 
components of the generator: insulating support films of lithium, 
electrolyte and composite cathode. The invention includes preferred 
embodiments and also describes means to obtain conductive and cohesive 
metallic deposits for the metallic layer which is compatible with lithium 
as well as for the lithium base intermediate layer. The quality of the 
weldings obtained according to the embodiments of the invention, between 
lithium and its alloys and certain hard and compatible metals is 
sufficient to preserve the electrical contacts of the anode from an 
oxidation of the surface of lithium by the surrounding gaseous phase. 
Another advantage of the devices according to the invention is to ensure 
an efficient heat transfer between the sheets of the generator and the 
outer casing of the latter. This aspect is particularly important for the 
safety of polymer electrolyte lithium generators where no free liquid 
electrolyte is present to facilitate heat exchanges between the generator 
per se and its external casing. 
(b) Description of Prior Art 
The development of primary and rechargeable lithium generators, has been on 
the increase during the latter years following an increasing demand for 
dense and light sources of energy. The important density of energy and the 
remarkable properties of preservation of lithium batteries give them a 
noted advantage over the other available systems which operate in aqueous 
media. However, a generally high manufacturing cost, a power which is 
sometimes limited at low temperature as well as consideration of safety 
with respect to the use of lithium still limit their use to small 
batteries and specialized markets. 
One way to remedy these limitations consists in replacing the liquid 
organic electrolytes presently used in lithium generators by thin films of 
polymer electrolytes generally consisting of polyether complexes and 
lithium salts. It is known that plastic films may be prepared rapidly and 
with large surfaces, by means of automated processes, in the form of thin 
films of the order of a few micrometers thick. These films, which are 
cheap to produce, enable, in principle, to produce large size and high 
power generators by a mere increase of the surface of the generator in the 
form of thin films. On the other hand, the preparation of an all solid 
generator by using non-fusible solid polymers, instead of organic liquids, 
enables, in principle, to produce a safer system because it is more 
susceptible of limiting the speeds of reactions of the chemical reactants 
with one another or, in case of accidental exposure to ambient air or 
water. The polymers which are capable of being used in such solid state 
generators have been described in previous patents (U.S. Pat. Nos. 
4,303,748; 4,578,326 and 4,357,401) as well as ways of assembling them 
(U.S. Pat. Nos. 4,897,917; 4,824,746 and French Patent No. 87 08539). 
An increase of the active surface of lithium generators when polymer 
electrolytes are used is however met with the difficulty of developing 
equivalent surfaces for the current collectors of the anode and the 
cathode. A practical solution consists, for example, in the case of the 
cathode, to use aluminum and, in the case of the anode, to use the sheet 
of lithium per se as current collector. This approach is sometimes used in 
coiled organic liquid electrolyte generators, for example in AA, C or D 
formats; in this case, the anode consists of a film of lithium having a 
thickness of about 130 micrometers (.mu.). At such a thickness, lithium is 
sufficiently resistant to be freely handled by means of assembling 
machines and the collection of current from the anode is then ensured 
through the end of the sheet of lithium or, if needed, by means of 
transverse metallic tongues which are fixed to the film of lithium at 
regular intervals in order to reduce the ohmic drop in the collector. This 
solution is difficult to transpose in the techniques used for polymer 
electrolytes generators which use much thinner assemblies and which 
require lithium thickness between 40 and 1 micrometers. At these 
thicknesses, the films of lithium are much less mechanically stable and 
should be supported (e.g. U.S. Pat. Nos. 4,824,746 and 4,897,917) in order 
to be handled by assembling machines. The limited electrical conductivity 
of thin metallic lithium prevents on the other hand, in the case of coiled 
batteries, to collect the current which has accumulated at the end of the 
coil since the length to be drained is substantial and causes in a 
substantial ohmic drop in the collectors. This limitation, which is due to 
the thinness of the films and the lengths to be used in a technique based 
on ultra-thin films, therefore imposes a lateral collection of the coiled 
device in order to reduce the distance to be collected. This observation 
is also true in the case of generators which are made by stacking 
discontinuous thin batteries or are mounted in zig-zag in order to reduce 
ohmic drops. A known way to ensure lateral collection consists in applying 
transverse conductive tongues at regular intervals of the coiled anode or 
cathode in order to reduce the length to be drained. 
However this possibility is hardly suitable for very thin films (local over 
thickness or low mechanical property of the tongue). Another possibility 
consists in laminating the anode of lithium on a thin inert metallic 
collector thereby enabling a lateral collection, through conventional 
processes of welding, on the inert collector. However, this additional 
metallic collector for the anode has been found to be extremely damaging 
in terms of weight and cost. By way of example, the cost of nickel or 
copper sheets, which are compatible with lithium, is about 1$/ft.sup.2 at 
the required thicknesses (e.g., 5-10.mu.). 
The manufacture of ultra-thin capacitors including metallized plastics by 
pulverizing a lateral collector on the edge of the coiled films represents 
a more interesting model for the technique of assembling lithium batteries 
based on polymer electrolytes. This type of capacitor generally consists 
of two identical insulating plastic films (polypropylene or polyester, 
about 3 to 30 micrometers) which are metallized on one face, with the 
exception of one non-metallized lateral band, and are co-wound with a 
slight offset so as to be able to collect each of the films at one 
opposite end by means of a metallic deposit applied on the metallized end 
of each of the two films. The electrical contacts used in these devices 
are generally based on zinc, aluminum or silver applied in the form of 
conductive pastes including an organic binder or in the form of deposits 
obtained by pulverizing: by flame spray or with an electrical arc (or 
shooping) in the case of zinc and aluminum. The latter type of contact 
outlet, known in the industry of capacitors, is described in the European 
Patent Application published under number 0073555 and French Patent 
Application published under number 2,589,620. 
It has been observed experimentally that these types of assembly and 
lateral contact outlet, which are compact, rapid and economical may be 
adapted to polymer electrolyte generators when inert metallic collectors 
are used, for example, when the collector for the cathode is aluminum. Up 
to now, these processes would not seem to be easy to directly transpose to 
the collection of lithium anodes consisting of thin lithium films for the 
following reasons: 
the pulverization of zinc by flame spray used in capacitors is not 
compatible for lithium generators because of the release of water due to 
the combustion; 
the compositions of silver or zinc powder, generally based on organic 
binders of the epoxy type are not chemically stable in the presence of 
lithium, particularly at high temperatures; 
the chemical reactivity of lithium prevents the use of known metals such as 
zinc and aluminum and their alloys which are normally used for 
pulverization under an electrical arc (shooping) during the manufacture of 
the capacitors. As a matter of fact, it has been experimentally observed 
that these metals, react spontaneously with lithium to give hard and 
friable inter-metallic compounds which prevent the formation of a slightly 
resistive and reliable electrical contact; 
the metals which are compatible with lithium such as nickel, iron, copper, 
molybdenum, etc. have very high melting points and for this reason appear 
to be hardly applicable directly by vaporization on a multilayer assembly 
of lithium films and plastic materials. By way of example, tests made by 
the Applicant with a commercial device for plasma pulverization (Plasma 
Spray) with a Medco device (Division of Perkin-Elmer) Model MBN using 
nickel or copper powder as coating metal, show that there is an important 
heat degradation of the plastic films, which are PP insulating material 
and polymer electrolyte of the generator, when the metal is projected with 
a hot inert gas on the lateral border of the anode of a coiled generator. 
In principle, the technique of pulverization with an electric arc of these 
same metals seems to present the same difficulty because of thermic shock 
with the other plastic components of the generator. 
SUMMARY OF INVENTION 
The present invention aims at solving the difficulties associated with the 
lateral collection of lithium film anodes in thin film polymer electrolyte 
generators. The invention describes devices for providing compact lateral 
contacts, which are only slightly resistive and are chemically stable, on 
anodes of ultra thin lithium sheets. The invention also comprises 
processes for the rapid application of these contacts so as to facilitate 
the production of reliable and economical ultra thin polymer electrolyte 
generators. Other advantages of the invention will appear in the 
description which follows. 
The present invention describes an arrangement of lateral electrical 
contact outlets on thin lithium sheets used as anodes in thin 
electrochemical devices (less than 150 micrometers per elementary cell) 
utilizing substantial lengths of films, which are generally in the form of 
cylindrical windings, flat or in the form of a stacking of one or more 
thin batteries. 
The preferred devices according to the invention include an electrical 
contact provided on the lateral projection of the anode sheet(s) used as 
collector, in a polymer electrolyte generator. These contacts are 
preferably obtained by application of one or more conductive metallic 
layers on the surface and/or the sides of the edges of the anode sheets so 
as to facilitate the electrical collection of the anode assembly and also 
to facilitate heat exchanges between the nucleus of the generator and its 
external casing.

DESCRIPTION OF PREFERRED EMBODIMENTS 
The preferred devices are described schematically in FIG. 1 with their main 
characteristics. FIG. 1a illustrates a cross-section of the laminated 
sheet of the generator with lateral projection of the lithium anode, x, on 
which contact may be established. On this Figure, y represents, by way of 
non-limiting example, the projection of the collector of a cathode 
enabling the application of a second lateral contact, which is also 
compact, obtained by utilizing known techniques used with electrical 
capacitors; silver conductive pastes, zinc and aluminum powders, welding 
tin . . . directly applied on the inert collector. 
FIGS. 1b, 1c and 1d illustrate three preferred embodiments of lateral 
contacts adapted for the collection of anode sheets of lithium not 
provided with inert collectors. The possible materials used to constitute 
the various layers illustrated are identified in the description and the 
examples which follow, as well as the main thermic, electrical and 
mechanical processes enabling to obtain optimum electrical and thermic 
contacts. A preferred way to produce the devices of the invention consists 
in pulverizing at least one of the metallic layers of the lateral contact. 
The advantages of the layers obtained by pulverization are: the 
compactness of the deposit to reduce the over-crowding of the contacts, 
the capacity of following the surface contour of the substrate without any 
risk of mechanical damage in the contact zone, the capacity of optimizing 
the heat exchange surface and the surface collection of the entire lateral 
contact surface of the generator. 
Figures f, g and h, illustrate three preferred embodiments of generators in 
which the devices of the invention may be used. FIG. 1f illustrates a 
cylindrical winding device with central nucleus 1, in which, at the upper 
end, there is a collection device for the anode, m, made with either of 
arrangements of FIGS. 1b, 1c or 1d. The lower end includes, by way of 
example, a device, n, for lateral collection, illustrated at 1e in which k 
is a metal which is in contact with the inert collector of the cathode. 
Element 1g illustrates a flat generator obtained by winding at least one 
laminated element, illustrated in FIG. 1a, on a flat mandrel, o, also 
collected at the ends, m and n. FIG. 1h, illustrates a flat generator 
consisting of one or more laminated elements, illustrated in FIG. 1a, 
individually stacked or folded in zig-zag shape and also collected at the 
ends, m and n. 
A first preferred embodiment of the invention is illustrated in FIGS. 1a 
and b. This device consists of an added intermediate metallic layer g, 
made of lithium or its alloys and thus enables to reduce the thermic shock 
produced on the other plastic components of the generator, by applying and 
welding low melting metal on the projection, x, of the sheets of the 
anode, b. This layer is applied at the lateral ends, and if needed on the 
edges, of the stacked sheets of lithium of the generator. This 
intermediate metallic layer is deposited under conditions enabling the 
production of a relatively dense, conductive and cohesive layer g, of 
about 1 mm, which intimately welds and mechanically consolidates the 
different sheets of the anode, b, between one another so as to prevent 
losses of electrical contact by a possible oxidation at the surface of the 
sheets. A preferred way of applying this intermediate metallic layer 
consists in contacting, under an inert atmosphere, the edges of the sheets 
of lithium with lithium in liquid form, or close to its melting point, by 
means of a process such as pulverization of droplets of lithium or alloys 
thereof having lower melting points. The intermediate metallic layer, g, 
thus constituted, facilitates the application of a second more rigid 
metal, ff, selected for its compatibility with the lithium of the second 
intermediate layer, and also facilitates electrical and thermic exchanges 
between the nucleus of the generator and its external casing. In this non 
limiting example, the generator includes, in addition to the sheets of 
lithium, an insulating film of polypropylene which may or may not adhere 
to the sheet of lithium, a, the electrolytes of the generator, c, the 
cathode, f, and its collector, e. These films are more or less offset with 
respect to one another by plurality of mm. These offsets are very 
important relative to the true thicknesses of the films which are of the 
order of 1-40 microns; on FIG. 1, the thickness of the films is amplified 
disproportionately to facilitate its understanding. 
The use of a metal such as lithium or its low melting alloys, g, as an 
intermediate metal serving as contact outlet with the thin sheets of the 
anode has the following advantages: 
1) it solves the problem of chemical compatibility of the added metal with 
the sheets of lithium; 
2) it enables to ensure an intimate electrical and thermic contact (lithium 
easily welding to itself by melting and/or mechanical pressure) and 
consolidates the lateral end of the anode; 
3) it enables some possibility of deformation of the contact zone during 
thermic or electrochemical cycle of charge/discharge (lithium and some of 
its alloys being highly malleable); 
4) the low melting points of lithium (180.degree. C.) and of some of its 
alloys facilitate their application on the thin sheets of lithium even in 
the vicinity of various plastic films of the generator; 
5) the capacity of lithium to produce a coherent and dense deposit enables 
to protect the area of contacts of the sheets from oxidation by impurities 
which may be present within the generator. 
The processes of applying metal such as lithium so as to constitute this 
intermediate metallic layer, g, are however associated with a major 
difficulty, e.i., the need to heat lithium or its alloys at a temperature 
close to the melting point without risking to cause the oxidation of 
lithium and without risking to melt the plastic components which are 
adjacent the sheets of lithium. Preferred processes are described to solve 
this problem, such as mechanical pulverization or pulverizing under 
electric arc, under inert atmosphere, of liquid or semi-liquid lithium at 
a temperature enabling the welding of the sheets to the added metal. 
Alternatives to the process of pulverization are also possible, such as by 
producing the intermediate layer from alloys of lithium having low melting 
point. The compositions of the lithium base alloys may be selected, by way 
of non-limiting example, among the following binary systems: Li-Ca, Li-Sr 
and Li-Na, Li-Mg, described in the text book "Constitution of Binary 
Alloys" Ed. Max Hansen published by McGraw-Hill Book Company, N.Y., or 
among more complicated systems including these elements whose compositions 
are rich in lithium and which are substantially liquid at temperatures 
lower than 350.degree. C. 
FIG. 2 illustrates, by way of example, a device for pulverizing molten 
lithium through a mechanical process which utilizes a jet of hot inert gas 
to project droplets of lithium in particular form, which is liquid or 
semi-liquid, thereby producing electrical contact of good quality on the 
edges of the sheets of lithium. The main elements of this Figure are: a, a 
vat containing lithium or its alloy in molten state m, b, the impervious 
cover of the vat a, c, heating elements for vat a and a hot inert gas 
inlet g, d, a capillary tube of internal diameter of about 0.4 mm, e, a 
pulverization nozzle, f, an external tube for the circulation of hot gas. 
In this device, a jet of molten metal, 1, is obtained by forcing the 
lithium to rise, by means of an inert gas under pressure introduced at k, 
in a capillary tube d so as to produce a jet of liquid or semi-liquid 
particles which is carried with a hot inert gas which circulates in the 
pulverization nozzle e. A protection sheath h also flushed with a colder 
inert gas entering at i and diffused at j, enables to use the device in 
the presence of oxygen or dry air. 
Other variants of this mechanical process for the production of the 
intermediate layer may be used, in particular by pulverizing molten 
lithium in an electric arc, supplied by two lithium rods, by means of an 
inert gas which projects the fine droplets of liquid lithium against the 
sheets of the anode. This process which is derived from zinc or aluminum 
shooping may be carried out by directly utilizing rods of lithium or 
lithium rich alloys to generate the electrical arc; preferably, these rods 
will be extruded directly in the proximity of the electrical arc. 
A second contact outlet preferred device based on an alternative way of 
producing the intermediate metallic layer is illustrated FIG. 1c. It 
consists in providing, when producing the anode film and when assembling 
the generator, a free lithium projection, x, relatively important, 
preferably between 0.2 and 1.0 cm, to enable the production, after 
assembly, of an intermediate metallic layer, i, formed from the projection 
of the anode sheet. The intermediate conductive layer, i, is preferably 
prepared by compaction and self-welding of the ends of the films with one 
another. One way of producing this intermediate layer in-situ without any 
risk of oxidation of the surfaces of lithium, consists in welding the end 
of the films with one another by mechanical pressing or local welding of 
lithium, by ultra-sonic wave or by melting. 
In the two devices 1b and 1c, based on the production an intermediate layer 
consisting of lithium or alloys thereof, it is necessary to apply a second 
conductive layer, respectively f and h, consisting of a metal which is 
rigid and compatible with lithium. This second metallic layer is essential 
and should be very intimately welded with the lithium of the intermediate 
layer to maintain the property of electrical contact between the anode and 
the external casing of the generator in spite of a possible superficial 
oxidation of lithium or its alloys. The application of a second layer, f 
or h, on the lithium base intermediate metallic layer, preferably nickel, 
copper, iron, molybdenum, titanium or alloys thereof is facilitated by the 
increase of mechanical behavior of the multilayer anode/intermediate layer 
assembly and by the fact that the metallic layer, g or i, separates and 
protects the plastic components of the generator against a thermic or 
mechanical shock resulting from the insertion of this second metal. This 
happens, for example, when applying metal, f or h, by processes of 
pulverization by plasma or electrical arc or still, more easily, by 
mechanical, thermic or electrical processes, for example, by ultra-sonic 
treatment, melting or spot-welding. These processes are used to fix and 
intimately weld the second metal, f or h, to the metal of the intermediate 
layer, g, so as to be able to produce a complete lateral current collector 
enabling the passage of current and heat through the external sheath of 
the generator. 
More generally, the provision of an intermediate metallic layer which 
separates the sheets of lithium from the second layer of a rigid metal 
which is compatible with lithium presents the advantage of well 
consolidating the sheets of lithium with one another and above all of 
protecting the other plastic components of the generator from thermic or 
mechanical shocks. This improvement enables to substantially reduce the 
width of the lateral projections of the electrodes which are required to 
prevent thermic degradations and accidental short-circuits resulting from 
the application of external contacts. 
A third preferred lateral contact outlet device on the lithium anode of an 
electrochemical generator is illustrated in FIG. 1d. This simple device is 
particularly well adapted to a polymer electrolyte generator. It is 
obtained by directly producing a pulverized layer of a metal which is 
compatible with lithium, j, more particularly copper, nickel, iron or 
alloys thereof, in intimate contact with the end of the sheets of lithium 
or the anode. The interest of this specific device is to optimize both the 
electrical and thermic conductivity of the lateral conduction layer zone, 
particularly when the metal is in direct contact with the sheets of 
aluminum and is based on copper. We have verified that these devices may 
be obtained by pulverization under electric arc and it was established, by 
means of tests, that an electrical contact of quality is obtained on thin 
sheets of lithium, without thermic damage for the plastic components, in 
spite of the fact that the pulverized metals have very high melting 
points, over 1000.degree. C. Production of conductive metallic layers 
which adhere to lithium is obtained, by pulverization under an electric 
arc between two copper wires of 1.6 mm diameter which are continuously 
supplied by means of a jet of local compressed air applied at the level of 
the electrical arc. The power used for the arc is 1-3 kW. Under the 
experimental conditions used and with the selected designs, no thermic 
damage or short-circuit was observed on the generator. A process of 
pulverizing these metals which are compatible with lithium under an 
electric arc therefore enables to prepare the contact outlet device of an 
anode of lithium without the inert collector film of FIG. 1d, rapidly, 
safely and economically. In particular, the pulverization of copper under 
an electric arc, on lithium, may be carried out under dry air as well as 
under an inert atmosphere and does not result in dusts of reactive 
lithium. Moreover, the use of copper as metal contact ensures an optimal 
thermic exchange capacity between the generator and its external casing. 
FIG. 3 illustrates a laboratory device used to demonstrate the quality of 
the lateral electrical contacts produced on free sheets of lithium. A 
symmetrical winding 3c, illustrated schematically, is produced by 
co-winding, on a plastic nucleus of 1.3 cm diameter, the combination of 
the following films: 
a--3 films of bi-stretched polyethylene 28.mu. thick and 12.1 cm wide, 
b--a film of aluminum, 20.mu. thick and 11.4 cm wide, 
c--a film of lithium, 35.mu. thick and 12.7 cm wide. 
The respective positions of these five films are indicated in FIG. 3a. The 
film of lithium exceeds the three films of propylene, placed at the same 
height, by 3.2 mm while the film of aluminum is set back by 3.2 mm with 
respect to these three films. FIG. 3a which is used to describe the films 
and their positions, does not enable to visualize the high ratio between 
the width of the projections and the thickness of the films, since the 
latter are illustrated with an enlarged thickness by a factor of about 100 
to facilitate the identification of the films. In the medallion 
illustrated in FIG. 3b, this ratio is reduced to 10, which already enables 
to understand more easily why it is possible to contact the excess of 
lithium film with a pulverized metal without for this reason 
short-circuiting the film of aluminum which is set back, e, and which is 
accessible only through opening, d, corresponding to its thickness. FIG. 
3c illustrates a winding of 4 meters produced with the five films 
described in FIG. 3a on a plastic mandrel of 1.5 mm, f. The representation 
is schematical and illustrates only that a number of lateral turns of 
contact outlet, g and g' are schematic and the various contact devices 
under study are described in the example which follows. Measurements of 
contact resistances between lithium and the lateral collectors are 
obtained by a 4 point method. A current of 10 Amp. is allowed to circulate 
between points P1 and P4, FIG. 3c, while the intermediate points, P2 and 
P3, are used as probes to measure local contact resistances. The film of 
aluminum, b, is electrically accessible at h, and it is intended to detect 
possible short-circuits resulting from the application of various lateral 
contacts produced according to the invention. The relative thickness of 
the assembly of co-wound films is determined so as to be near the spaces 
between the films and the lateral projections of a complete generator such 
as described in the example which follows. 
FIG. 4 describes more in detail a complete polymer electrolyte generator 
obtained by winding various components by utilizing either of the contact 
outlet devices for the sheets of free aluminum of the anode: FIGS. 1b, 1c, 
1d and 1e. The relative positions of the films used are indicated in FIG. 
4a. A variant of this arrangement is also schematically illustrated in 
FIG. 4b, in which, lithium without additional metallic collector is 
supported on a film of adherent polypropylene in order to facilitate 
certain modes of mounting. The films used to produce the generator and the 
manner of obtaining the lateral projections required for the lateral 
collection of the anode are illustrated in 4a, 4b and 4c, they are: 
a--an insulating film of polypropylene 20 microns thick, 
b--a sheet of free lithium 35 microns thick laterally projecting at the 
upper end by about 6.3 mm relative to the cathode and its aluminum 
collector, 
c--a polymer electrolyte, 30 microns thick, laterally projecting past the 
collector of the cathode at the upper end by 2.2 mm on the one hand, as 
well as past the sheet of lithium at the other end of the generator on the 
other hand, 
d--a vanadium oxide base composite cathode film 45 microns thick in lateral 
recess on its aluminum collector, 
e--an aluminum collector for the cathode, 18 microns thick, laterally 
projecting beyond the lower end by about 6.3 mm relative to the sheet of 
lithium, 
f--a second rigid metal, with high melting point, chemically compatible 
with lithium and having good electrical and heat conductivity to enable 
heat exchange towards the outside of the generator, 
g--plastic nucleus or internal mandrel of the generator having an external 
diameter of about 1.3 cm, 
h--lateral contact outlet device of the cathode applied on the projection 
of its aluminum collector, 
i--a lithium base intermediate metallic layer in intimate contact with the 
sheets of lithium and with a second metal, f, which is rigid and 
compatible with lithium. 
In full details, the contact outlet device of the anode illustrated on the 
generator of FIG. 4c is the one of FIG. 1b as obtained from the 
pulverization apparatus of FIG. 2. However, the elements f and j may also 
illustrate the contact outlet device produced with the devices of FIGS. 1c 
and 1d. In the latter case, element f is removed and element j then 
consists of a metal which is rigid and compatible with lithium, preferably 
obtained by arc pulverization. 
The manners of obtaining lateral projections of the cathode and the lateral 
contact outlets are given by way of non-limiting examples, and many other 
technical solutions are applicable to this electrode, for example welding 
of the sheets of aluminum collector, application of silver base conductive 
paste, pulverization of zinc or aluminum. 
Examples 1 to 3 describe contact outlet devices according to the invention 
and the ways of producing them. These examples are carried out on the 
projections of the sheets of lithium of the two ends of the symmetrical 
windings described in FIG. 3. The interest of these devices is to enable 
to specifically study the contact resistance between the sheets of lithium 
and their lateral collection device. The external dimensions of the rolls 
used are: width 13.6 cm, diameter of internal plastic nucleus, g, 1.3 cm, 
external diameter of winding, 3.0 cm. The length of the films used was 4 
meters. The values of the local resistances are obtained through a 4 point 
measuring device illustrated in FIG. 3c which enables to determine local 
contact resistances. In this manner, the electrical contact resistance 
between the sheets of lithium and the lateral contact device is verified. 
Three different tests are then used to evaluate and compare the quality of 
the contact: 
1--measurement of the contact resistance after mounting the lateral 
collector; 
2--modification of this resistance as a function of time at 60.degree. C. 
for a plurality of days, i.e., the stability of the collectors as a result 
of shocks and thermic cycles; 
3--measurement of the resistance after controlled oxidation, at 60.degree. 
C., of lithium and its alloys by the gaseous phase. This test is carried 
out by maintaining the winding of FIG. 3 inside a sealed enclosure 
containing about 500 ml ambient air so as to cause a superficial oxidation 
of any surface of lithium which is accessible to the gaseous phase. The 
lateral collector of the anode of lithium should include an interface 
lithium or lithium alloy/metal compatible with lithium and which is 
non-oxidizable and non-reactive, and the weld therebetween should be 
sufficient to be resistant against a superficial oxidation of the 
accessible surfaces. 
Examples 4 to 7, describe the contact outlet devices mounted on complete 
generators and confirm the quality of the contacts through an analysis of 
their global performances. These examples describe many types of contact 
devices made and models of generators produced. 
EXAMPLE 1 
The first example describes the way of making the contact outlet device 
illustrated in FIG. 1b on the symmetrical winding 3c. 
To make device 1b, the device for pulverizing molten lithium illustrated in 
FIG. 2 is used. The conditions of use of the device are the following: 
temperature of the bath of molten lithium: 250.degree. C., approximate 
temperature and flow of the jet of helium, 250.degree. C. and 150 l/min., 
pressure above the molten bath: 30 psi. The jet of molten lithium is 
projected against the end of winding 3c, including a 35 micron projection 
of a film of lithium. The deposit corresponding to the intermediate 
conductive layer g, FIG. 1b, is carried out during three passes of about 5 
seconds and has a relatively uniform thickness of 1 mm. On the external 
face of the intermediate layer, there is then applied a sheet of nickel, 
second hard metal compatible with lithium, f of FIG. 1b, which is welded 
by local melting of lithium in contact with nickel. The contact 
resistances corresponding to the weldings of the two collection layers g 
and f are very good: less than 0.02 milliohms of slice surface of the 
sheets to be collected. These contact resistances are inferior to the 
resistances observed between the external collectors and the lateral 
collectors g and g', of FIG. 3c, for example in the case where the 
contacts are merely mechanical contacts. No significant change is seen 
after storage at 60.degree. C. for 7 days and after a superficial 
oxidation of the surfaces of lithium which are in contact with the gaseous 
phase during 7 days at 60.degree. C. No short-circuit is noted between 
aluminum, h, FIG. 3c, and the lateral collectors thus produced. After 
dismantling, an examination of the mechanical properties of the deposit of 
pulverized lithium confirms the cohesion of the intermediate metallic 
layer and its adhesion with the sheets of lithium. The unwinding of the 
films indeed produces a pulling of the sheet of lithium outside the 
welding zone with the projected lithium. On the other hand, examination 
after dismantling of the films indicates no significant degradation of the 
film of propylene in the proximity of the zone where molten lithium has 
been projected; however, it can be noted, after a test for pollution in 
air, that the lithium of the intermediate zone is gray and oxidized in 
surface. The low resistances noted in this case confirm that the weldings 
between the sheets, the particles of the intermediate zones and the metal 
of the second conductive layer are sufficiently mixed to be resistant 
against a superficial oxidation of lithium or its alloys. 
An equivalent test made by using an alloy of lithium and calcium 10% at. in 
the device of FIG. 2 leads to equivalent resistances and enables to reduce 
the temperature of the bath of lithium, m, FIG. 2, and to reduce the risks 
of short-circuit or thermic shocks on the generator. 
Two other tests were made by applying in one case a high purity silver base 
epoxy and in the other case zinc, projected by shooping on the lithium of 
the intermediate face, give a low initial resistance of 0.08 milliohms for 
the surface of the lateral slice of the sheets of lithium to be collected, 
i.e. 1.4 cm (or 35.mu..times.400 cm) which rapidly increases after storage 
at high temperature during many days and after a test for pollution in air 
3 milliohms. These latter tests confirm that the solution traditionally 
used for electrical capacitors, are not applicable to the direct lateral 
collection of the anodes of lithium of a generator. 
EXAMPLE 2 
This example is directed to the device of FIG. 1c as well as the ways of 
producing it with the winding of FIG. 3c. 
In this type of lateral collection device, the intermediate conductive zone 
of lithium, i, of FIG. 1c is obtained after assembling the winding by 
compressing the edges of lithium 3 mm wide and by welding them together by 
means of an ultrasonic probe. The intermediate layer thus obtained is 
about 1 mm thick. A sheet of copper is thereafter applied thereto, and the 
latter is welded to the intermediate layer by local melting of lithium, 
under inert atmosphere, by means of a heating plate so as to constitute 
the second conductive layer h, FIG. 1c. 
The contact resistances of these collection devices are good, about 0.1 
milliohm for 1.4 cm.sup.2 of lateral surface of the sheets to be collected 
and the devices have a good resistance at 60.degree. C. and under a test 
for pollution by the gaseous phase. 
A variant of this test consists in previously coating the copper sheet, h, 
with a lithium-calcium alloy of lower melting point (10% at. Ca) and which 
is adherent, so as to facilitate the melting and local welding of the 
sheet to the intermediate layer i. The mechanical adhesion confirms in 
this case the quality of the contact device thus produced. 
A test which is equivalent to the previous ones in which a powder of copper 
or nickel is used in a device for plasma pulverization so as to constitute 
the second metallic layer h, FIG. 1c, also gives resistances which are 
equivalent and stable in time. 
A test which is equivalent to the previous ones in which no inert metal 
compatible with lithium is welded to the intermediate conductive layer i, 
FIG. 1c, is made. A metal such as steel or nickel is mechanically applied 
against layer i, so as to simulate a direct mechanical contact between the 
inter-metallic layer and an external casing of a generator. The resistance 
of this contact is initially low, about 0.05 to 0.10 ohm; however this 
value increases strongly as soon as the contact is heated at 60.degree. C. 
or undergoes a pollution test. This test confirms the need to finish the 
natural collection device of the sheets of the anode with a rigid metal, 
which is inert and compatible with lithium so as ensure the stability of 
the contact at the external terminals of the generator without casing. 
The absence of short-circuit when applying the second conductive metallic 
layer h through different processes, confirms the interest of the second 
intermediate conductive layer based on lithium or alloys thereof to 
mechanically consolidate the end of the winding 3c and to protect the 
plastic components thereof during thermic shocks caused by the application 
of the second inert metal h. 
EXAMPLE 3 
This example is directed to the device of FIG. 1d as well as the ways of 
producing it with the winding of FIG. 3c. 
This device containing a single layer is obtained by pulverizing under an 
electrical arc a layer of copper, g, FIG. 1, about 0.5 mm thick directly 
against the ends of the sheets of lithium which projet by about 3 mm. The 
apparent difficulty of this type of simple device, is to intimately weld a 
metal melting at about 1080.degree. C. on a thin metal melting at 
180.degree. C. and without on the other hand, damaging the other plastic 
films, a, FIG. 3a, of the winding, which are located in the vicinity (3 
mm) of the latter. The conditions under which this metallic layer is 
obtained are given in the description of FIG. 3 and also account for the 
designs of the windings, essentially, the ratio between the width of the 
projections, e, FIG. 3, and the space, d, FIG. 3, which separates the film 
and which results from the thickness of the set back film or films. The 
granulometry of the droplets produced during pulverization under arc, for 
example in the case of copper, also plays an important role when producing 
the conductive layer. It has been observed that the presence of a 
substantial portion of particles of a size substantially equivalent to the 
thickness of the films of electrolyte and the cathode obtained by 
adjusting the shape of the jet of compressed air which is injected in the 
electrical arc improves the reliability of the contacts thus established 
by reducing the risks of accidental short-circuit resulting from the 
accumulation of excessively fine powders in the zones where one of the 
conductive films is set back, d, FIG. 3b. The resistances of the contacts 
noted on devices obtained by respecting the dimensions indicated have very 
low contact resistances and an excellent behavior at 60.degree. C. and 
during pollution tests. The typical values obtained are from 0.01 to 0.02 
milliohms/cm.sup.2 of lateral surface of collector to be contacted. 
After dismantling, it is noted that, even after a test for pollution in 
ambient air, there is a very good coherence of the copper layer and a 
strong adhesion between lithium and the copper layer which has been 
consolidated by pulverization. 
The interest of this single layer device is that its simplicity and the 
nature of the materials used, for example copper, optimize to the maximum 
the electrical conductivity of the collection layer as well as its thermic 
conductivity which is required for the thermic operation of a generator 
and its safe operation. On the other hand, the combination of a rapid 
melting obtained under an electric arc with a jet of cold gas which 
projects the particles against lithium, makes this process particularly 
interesting for producing device 1d. 
A test made by utilizing iron instead of copper to produce the conductive 
collection layer j, FIG. 1, under air, produces a deposit which is less 
coherent and more resistive. However, the use of an inert gas improves the 
process as well as the appearance of the contacts thus produced. The use 
of nickel in an equivalent test gives contacts which are more coherent and 
cohesive even when air is used to project the molten metal under an 
electric arc. 
EXAMPLE 4 
This example describes how the contact outlet devices of the anode, 
schematically illustrated in FIG. 1, (b and c), may be used in a complete 
polymer electrolyte generator such as schematically illustrated in FIG. 
4c. 
The external characteristics of the generator used in the form of a 
cylindrical winding are: internal diameter of the plastic nucleus 1.3 cm, 
external diameter of the generator 3.3 cm, width of the winding 13.6 cm, 
length of the films used 4 meters. The elementary cell used for the 
example is that described in FIG. 4a. It is assembled and wound 
continuously by consecutive transfer/lamination, of the various films at 
high temperature. The capacity which has been introduced into the 
non-optimized generator is 10.9 Wh on the basis of an extrapolation of the 
performances of laboratory cells 4 cm.sup.2 using the same materials. 
Contact of the anode is made as in FIG. 1c by contacting and welding with 
ultrasonic waves the edges 3 mm wide of the lithium sheets, b, of FIG. 4a 
so as to constitute an intermediate layer i, about 1 mm thick. This 
intermediate layer is then used to protect the other films of the 
generator from a thermic and mechanical shock resulting from the 
application of a sheet of copper, h, by superficial fusion welding of the 
lithium of layer i. 
The device for lateral collection of the cathode used in this case 
comprises a thin layer, about 0.5 mm zinc, obtained by directly shooping 
on the projections of the aluminum collector of the cathode. FIG. 1e, 
describes this type of contact where k then consists of pulverized zinc. 
A precise verification of the quality of the contacts on the anode is more 
difficult to obtain with a generator of this size operating at 60.degree. 
C. An evaluation is made by means of measurements of the interruption of 
current during discharge. Currents of 0.4 to 4 Amperes, corresponding to 
discharges varying between 10 and one hour, are used. Such currents are 
required for applications of the electrical vehicle battery type. The 
global ohmic decreases observed are about 25 milliohms. These values 
substantially correspond to excepted values from measurements of the 
impedance of this type of battery made in laboratory at 60.degree. C. 
(about 80 .OMEGA./cm.sup.2) after deducting the other contact resistances 
of the complete measurement device. These results confirm that the 
resistance of the lateral contact device of the anode, evaluated in 
Example 2 to be 0.01 milliohm for a 1.4 cm.sup.2 section of lithium sheet 
to be laterally collected (35.mu. by 4 meters) is negligible as compared 
to the resistance of the electrochemical system taking into account the 
active surface of the entire winding of 10 Wh. 
An additional verification of the quality of the contact device of the 
anode is obtained by completely discharging the generator at variable 
rates. The rate of use of the active materials which have been observed 
correspond to expected values, within the precision of the measurements, 
which confirms that the entire surface of the anode is well drained by the 
lateral collector. The variation of the rate of use of the generator with 
a discharge current between 0.4 and 4 amperes moreover corresponds to that 
expected from the electrochemical characteristics of the battery, which 
confirms the good operation of the lateral contacts. The characteristics 
of ohmic decrease and of rates of utilization of the reactants are not 
affected in the cycles which follow a test of temporarily exposing the 
generator in ambient air (500 mls) at 60.degree. C. for 48 hours, which 
confirms the quality of the weldings used in the lateral contacts of the 
sheets of the anode. 
EXAMPLE 5 
This example is equivalent to the preceding example except for the 
intermediate zone of the contact outlet device of the anode which is that 
of FIG. 1b produced in the same manner as in example 1. The 
characteristics of the generator are equivalent to that noted in example 
4. 
This example and its illustration in FIG. 4c, shows well how the large 
collection surfaces resulting from this type of lateral contact outlet 
facilitate heat exchanges. The nature of the lateral contact, its small 
thickness and its surface highly contribute to the heat transmission 
between the nucleus of the generator and its external casing, particularly 
when the cylindrical winding rests directly against the casing, i.e. 
against the bottom and against the upper cover of the casing, not 
illustrated in FIG. 4. 
EXAMPLE 6 
This example uses the contact outlet device of FIG. 1d in which copper is 
directly pulverized by pulverization under an electrical arc against the 
edges of the sheets of lithium of a winding described in FIG. 4c and made 
with laminate 4a. In this case however, the copper deposit corresponds to 
deposit j of FIG. 4c, while sheet f is removed. The characteristics of the 
generator are equivalent to those of examples 4 and 5 and the small 
thermic heating observed the generator when depositing about 0.5 mm copper 
under air confirms the interest of this process to produce this lateral 
collection device of thin sheets of lithium. 
EXAMPLE 7 
This example is identical to the preceding one except for placing the films 
used to produced winding 4c which is that illustrated in FIG. 4b. In this 
case, the laminate used to produce the winding includes supported lithium 
and adheres on a plastic film until reaching the projection zone of the 
anode. The mechanical and electrical characteristics of the copper 
deposited confirm that the process of pulverization under an electric arc 
may be used to deposit very high melting metals, 1000.degree. C., on the 
lithium of a generator even if the latter is in direct contact with a 
plastic support.