Title: Battery with extractible air electrode
Field of the invention
5 The present invention relates to the technical field of batteries comprising an air
electrode and more particularly batteries comprising a case and inside the latter an
air electrode, a liquid electrolyte and the negative electrode. This negative
electrode can be a metal electrode.
10 State of the art
Metal-air batteries belong to batteries comprising an air electrode and use a metal
negative electrode, based for example on zinc, iron or lithium, coupled to the air
electrode. During discharge, the following reactions take place:
M -, M"' + rive' negative electrode (metal electrode)
O2 + 2-HzO + 4.e' -, 4.OH' positive electrode (air electrode).
Thus, oxygen is reduced at the air electrode and the metal of the negative
electrode is oxidized. Usually, an aqueous alkaline electrolyte is used.
These metal-air batteries have several applications, for example zinc-air batteries
20 are marketed for use in auditory prostheses.
Numerous studies have been carried out over several decades for the development
and optimization of air electrodes making it possible to produce electrochemical
generators of the metal-air type, known for their high energy densities and capable
of reaching several hundred Whlkg.
2 5 Air electrodes are also used in alkaline fuel cells.
An air electrode makes it possible to use atmospheric air, which is available in
unlimited quantity anywhere and at any time, as oxidizing agent for the
electrochemical reaction.
An air electrode i s a porous solid structure in contact with the liquid electrolyte,
30 which is generally an alkaline solution. The interface between the air electrode and
the liquid electrolyte is a so-called "triple contact" interface, in which the active
solid material of the electrode, the gaseous oxidizing agent (air) and the liquid
electrolyte are present simultaneously.
A description of the different types of air electrodes for zinc-air batteries i s
35 disclosed for example in the bibliographical article by V. Neburchilov et al., entitled
"A review on air cathodes for zinc-air fuel cells": Journal of Power Sources, 195
(201 O), pages 1271 to 1291.
When a metal-air battery is to be electrically charged, the direction of the current
is reversed and the following reactions take place:
Mn+ + n-e' + M negative electrode (metal electrode)
4.OH- -+ O2 + 2.H20 + 4.e- positive electrode (air electrode)
Thus, oxygen is produced at the positive electrode and the metal is re-deposited
by reduction on the negative electrode.
Although these batteries operate without a major problem in the discharge phase,
10 they are not stable in the charging phase; the weak point of the metal-air battery
during the charging phase is the air electrode, which is not designed to be used in
the reverse direction (i.e. under oxidation).
In fact, the air electrode has a porous structure and operates in the form of a
volumetric electrode in which the electrochemical reaction takes place within the
15 volume of the electrode, at the interface between a gas (oxygen from the air), a
liquid (the electrolyte) and a solid (the active material of the electrode and
optionally a catalyst): this i s the triple contact. This porous structure i s important
because it offers a necessary large reaction surface area, and therefore a high
current density, as the density of the gaseous oxygen i s low with respect to a liquid.
20 For example, the molar density of the oxygen in air is equal to about 0.03 mollL
while water has a density of 55 mollL.
Thus, generally, an air electrode is manufactured from carbon granules with a
high surface area, such as vulcana XC72 marketed by Cabot. The surface area of the
carbon can also be further increased by reaction with a gas, such as C02, before i t s
25 incorporation into the air electrode. The carbon granules are then agglomerated in
order to form the air electrode, using a hydrophobic fluorinated polymer such as a
fluorinated ethylene propylene copolymer (FEP) marketed by Dupont. Document
WO 20001036677 describes such an electrode for a metal-air battery.
This large reaction surface area i s not necessary for the reverse oxidation reaction
30 at the positive electrode during the charging phase, since the concentration of active
material is much higher. On the contrary, the porous structure of the air electrode
has the drawback of being fragile: it was found by the inventors that the porous
structure of the air electrode was mechanically destroyed by the release of gaseous
oxygen when it was used for oxidation of the liquid electrolyte to oxygen. In fact, the
35 hydraulic pressure generated within the air electrode by the production of gaseous
oxygen is sufficient to cause breaking of the bonds between the carbon granules
constituting the air electrode.
The inventors also noted that the catalyst, which is added to the air electrode in
order to improve the energy yield of the oxygen reduction reaction such as
5 manganese or cobalt oxide, is not stable at the potential necessary for the oxygen
reduction. Furthermore, corrosion takes place by oxidation of the carbon in the
presence of oxygen and i s accelerated at high potentials.
In order to overcome this, some authors use a more resistant oxygen reduction
catalyst coupled with an oxygen release catalyst in the bifunctional electrodes
10 composed of two electrically-coupled layers (see for example patent US 5,306,579).
Unfortunately, these bifunctional electrodes have a short lifetime and a limited
number of cycles because the structure of these electrodes does not withstand the
release of gas produced over long periods of time and because the catalyst is not
stable and the carbon corrodes at the potentials applied during charging.
15 These degradations of the air electrode during the charging phase significantly
reduce i t s lifetime and are one of the main reasons that prevent the commercial
development of electrically rechargeable metal-air storage cells.
As a result, the lifetime of the air electrode is shorter than that of the metal
electrode for batterieslcells used alternately in discharge and charge mode. Now, it
20 would be a waste to have to discard the batterylcell when the metal electrode i s
still usable.
Generally, the problem associated with the release of gas during charging at the
air electrode i s found for any battery comprising an air electrode.
25
Disclosure of the invention
Thus, one of the objectives of the present invention i s to overcome at least one
drawback of the state of the art described above.
30 To this end, the present invention proposes a cathode compartment for a battery
with an air electrode, comprising an air electrode and suitable for extractible
insertion into a battery case. The air electrode i s in the form of a plate and the
cathode compartment is liquid-tight. The cathode compartment also comprises an
electrical connection for connecting the air electrode to a positive terminal of a
battery, and a hollow cartridge having an air inlet and an air outlet, with at least one
flat face formed at least partially by the air electrode.
Thus, the air electrode is comprised within an extractible cathode compartment.
It i s thus possible to continue to use the negative electrode, in particular the metal
5 electrode of a metal-air battery, in a simple manner when the air electrode i s at the
end of i t s life. In fact, there is no need to dismantle the batterylcell assembly in
order to replace the air electrode.
Other optional and non-limitative characteristics of the cathode compartment are
as follows.
10 As a variant, the cathode compartment also comprises a rim on i t s face, formed at
least partially by the air electrode of the cartridge, in order to limit the compression
of the negative electrode, in particular when the latter i s made from metal.
The cathode compartment advantageously also comprises an additional air
electrode in the form of a plate at least partially forming another face of the hollow
15 cartridge, the other face being opposite to the face formed at least partially by the
air electrode.
The cathode compartment advantageously comprises a honeycombed mechanical
reinforcement arranged inside the cartridge, abutting the air electrode.
The cathode compartment can have a lower part and an upper part, the lower
20 part comprising the air electrode(s) and the upper part having at least one section
below the section of the lower part.
The invention also proposes a rechargeable battery comprising a case and inside
the latter:
- an air electrode;
25 - a negative electrode; and
- an electrolyte; and
in which the air electrode can be extracted from the case and inserted into a
compartment as described above.
Thus, it i s easy to replace the air electrode when it reaches the end of i t s life.
3 0 Other optional and non-limitative characteristics of the battery are as follows.
In the case in which the negative electrode is a metal electrode, the electrolyte is
a liquid electrolyte; the cathode compartment is moveable within the case. The
battery then comprises an electrically insulating separator between the air electrode
and the metal electrode and a flexible element. The separator, the cathode
35 compartment and the metal electrode are arranged so that the flexible element acts
on the cathode compartment so that the latter compresses the metal electrode via
i t s face formed at least partially by the air electrode. This flexible element can be
the battery case or a compression system arranged against one wall of the case.
Advantageously, the battery comprises a second air electrode incorporated into a
5 second extractible moveable cathode compartment as described above, and a second
electrically insulating separator between the second air electrode and the metal
electrode. The two cathode compartments and the metal electrode are arranged so
that the metal electrode is compressed between the two cathode compartments via
their faces formed at least partially by the air electrodes.
10 The battery can also comprise a second positive electrode for charging the battery.
In this case, the second positive electrode is advantageously arranged between the
cathode compartment and the negative electrode. The battery then also comprises
at least one spacer placed in contact with the second positive electrode in order to
facilitate the removal of the oxygen bubbles produced on the second positive
15 electrode during charging. As a variant, two spacers can be arranged one on each
side of the positive electrode. Thus, the spacer can be provided against a face of the
second positive electrode turned towards the negative electrode, respectively
towards the air electrode. In this case, the battery also comprises at least one
mechanical protection arranged between the spacer and the negative electrode,
20 respectively the air electrode, in order to protect them against the spacer.
Drawings
Other objectives, characteristics and advantages will become apparent in the light
25 of the following description, with reference to the drawings given by way of
illustration and non-limitatively, in which:
Figure 1 shows diagrammatically a cathode compartment used in a
battery according to the present invention;
Figure 2 shows diagrammatically in cross section the cathode
30 compartment in Figure 1 comprising an air electrode and a honeycombed mechanical
reinforcement;
Figure 3 shows diagrammatically in cross section the cathode
compartment in Figure 1 comprising two air electrodes and a honeycombed
mechanical reinforcement;
Figure 4 shows diagrammatically in cross section the cathode
compartment in Figure 1 comprising an air electrode, a honeycombed mechanical
reinforcement, and the cartridge of which has a rim;
Figure 5 shows diagrammatically an embodiment of a battery according
5 to the present invention comprising a case, a metal electrode, two cathode
compartments from Figure 2 and two separators;
Figure 6 shows diagrammatically an embodiment of a battery according
to the present invention comprising a case, a metal electrode, two cathode
compartments from Figure 4 and two separators;
10 Figure 7 shows diagrammatically an embodiment of a battery according
to the present invention comprising a case, two metal electrodes, two cathode
compartments from Figure 2, a cathode compartment from Figure 3 and four
separators;
Figure 8 shows diagrammatically an embodiment of a battery according
15 to the present invention comprising a case, two metal electrodes, two cathode
compartments from Figure 2, a cathode compartment from Figure 3, four separators
and a compression system;
Figure 9 shows diagrammatically an embodiment of a battery according
to the present invention comprising a case, a metal electrode, two cathode
20 compartments from Figure 2, two second positive electrodes, and four separators;
Figure 10 represents diagrammatically an embodiment of a battery
according to the present invention comprising a case, a metal electrode, two
cathode compartments from Figure 2, two second positive electrodes, four
mechanical protections, and four spacers;
2 5 Figure 11 shows diagrammatically a battery according to the present
invention in which the cathode compartment presents an upper part and a lower part,
the cross section of the upper part reducing with increasing distance from the lower
part; and
Figure 12 shows diagrammatically a battery according to the present
30 invention in which the cathode compartment has an upper part and a lower part,
both of which are rectangular, the cross section of the upper part being less than the
cross section of the lower part, thus forming a shoulder at the interface between
them.
35 Description
A battery with an air electrode according to the invention i s described hereinafter
with reference to Figures 1 to 12. Generally, the term "battery" is used herein to
denote any electrical element making it possible to store energy in chemical form
5 and to restore it in electrical form. Thus, this term covers equally the terms "cell",
"fuel cell", "regenerative fuel cell" and "storage cell".
Such a battery 1 comprises a case 11 and, inside the latter, an extractible air
electrode 22, a negative electrode 3 and an electrolyte 4.
The air electrode 22 can thus be removed from the case 11, for example by
10 sliding, so that it can be replaced when it reaches the end of i t s life or deteriorates,
due, for example, to the fact that the structure of the agglomerated granules of
carbon is too damaged. The air electrode 22 can also be moveable inside the case 11,
in particular in order to allow the compression of the negative electrode 3 as will be
described in greater detail hereinafter.
15 The air electrode 22 is preferably made from a porous material that conducts
electrons. This porous material i s for example a compound of carbon black, a cobalt
or manganese oxide-based catalyst, a hydrophobic binder such as HFP
(hexafluoropropylene) or PTFE (polytetrafluoroethylene), and a current collector
such as a collector in the form of a nickel grid. An anion-conducting polymer can be
20 added to the electrode as described in the patent WO 20101128242 A1, in particular
when the electrolyte i s aqueous. This polymer has the function of preventing the
carbonation of the aqueous electrolyte by the C02 contained in the air. The
hydrophobic binder has the double function of producing a mechanically integrated
porous structure from a powder the electron percolation of which is ensured by
25 contact between the carbon granules, and of being sufficiently hydrophobic to
prevent the electrolyte from passing through the electrode when the electrolyte is a
liquid.
The negative electrode 3 can be a metal electrode as in the case of a metal-air
battery. The material of the metal electrode i s preferably zinc, iron or Lithium. In
30 this case, the electrolyte i s a liquid electrolyte.
The battery 1 can also comprise a cathode compartment 2 comprising a hollow
cartridge 21 and an electrical connection 23 for connecting the air electrode 22 to
the positive terminal of the battery 1 (see Figures 1 to 4). The cathode compartment
2 i s suitable for extractable insertion into the case 11 of the battery. The cathode
35 compartment 2 i s preferably liquid-tight, for example to the Liquid electrolyte 4 of
the battery 1, in particular when the cathode compartment 2 is intended to
compress the negative electrode 3 as will be described below.
The cartridge 21 thus has a cavity in which air may circulate. The cartridge 21
also has an air inlet 24 and an air outlet 25 for the circulation of air within the
5 cartridge 21 and contact with the air electrode 22. The air used to supply the
cartridge 21 can be untreated, or treated in order to be for example humidified,
dried, decarbonated (removal of the COz) or enriched with oxygen.
The air electrode 22 is incorporated into the cathode compartment 2 in a sealed
manner in the form of a plate forming at least partially one of the faces of the
10 cartridge 21. The cartridge 21 can then have a cylindrical shape with at least one
flat face formed at least partially by the air electrode 22. In this case the cartridge
21 can be extractible by sliding, perpendicularly to the apothem of the cylinder.
Thus, replacement of the extractible air electrode 22 can be carried out easily by
simply removing the cathode compartment 2.
15 As a variant, an additional air electrode 27 can be provided in the cathode
compartment 2. This additional second air electrode 27 forms at least partially a
second face of the cassette 21 opposite to the face formed at least partially by the
first air electrode 22 (see Figure 3). In this case, the cartridge 21 preferably has a
cylindrical shape with two parallel flat faces.
20 The cathode compartment 2 can also comprise a honeycombed mechanical
reinforcement 26 inside the cartridge 21 in order to reinforce it. This mechanical
reinforcement 26 abuts the air electrode 22.
This mechanical reinforcement 26 is particularly advantageous when the negative
electrode 3 is a metal electrode in the form of a plate and the cathode compartment
25 2 and the metal electrode 3 are arranged so that the cathode compartment 2
compresses the metal electrode 3 via its face formed at least partially by the air
electrode 22, for example against a wall of the case 11, preventing the deformation
of the air electrode 22 when the metal electrode 3 is compressed.
In such an embodiment, the battery 1 comprises a separator 5 electrically
30 insulating the air electrode 22 from the metal electrode 3 and arranged between
them. The separator 5 is an element made from a material that is electrically
insulating and ion conducting, for example a polyelectrolyte, i.e. a polymer
comprising charged groups. As a variant, it can also be made from an electrically
insulating material that is permeable to the liquid electrolyte, for example a felt.
35 Provision can be made for the separator 5 to be attached to the air electrode 22
andlor to the negative electrode 3. Furthermore, the battery 1 comprises a flexible
element acting on the cathode compartment 2 in order to hold it against the
negative electrode 3 via the separator 5.
Compressing the metal electrode 3 i s advantageous for the following reasons.
5 During the charging phase of the metal-air battery, the metal ion i s reduced to metal
at the negative electrode which is deposited there when the potential at this
negative electrode allows. Now, under certain conditions, the metal i s deposited in
the form of a foam that is poorly adherent to the surface of the metal electrode.
This poorly adherent foam may detach from the electrode, causing a loss of active
10 material and consequently a reduction in the capacity of the battery. The inventors
noted that compressing the metal electrode during the charging phase limited the
formation of this poorly adherent foam. Furthermore, this compression also prevents
the metal electrode from deforming during repeated charge and discharge cycles by
ensuring a uniform, homogeneous and dense distribution of the deposition of metal
15 on the metal electrode.
The flexible element can be formed by the case 11 of the battery. The elements
that are placed inside the case 11 are inserted therein by force. The flexible
element can also be produced in the form of a compression system 6. This
compression system 6 is arranged against a wall of the case 11 and another element
20 of the battery 1, for example the cathode compartment 2 or the metal electrode 3.
The compression system 6 makes it possible to ensure the compression of the metal
electrode 3 once the cathode compartment 2 and the metal electrode 3 are in place
and after their insertion. The compression system 6 i s advantageously produced from
a flexible material, for example a flexible foam. An example of flexible foam would
25 be for example a polychloroprene foam (also called Neoprene@), preferably the
neoprene foams marketed under the name BulatexB, in particular Bulatex C166, by
the Hutchinson company. Another example of such a foam would be the product
SylomerB G, a polyurethane foam marketed by the Plastiform company. The foam i s
preferably a closed-porosity foam and isolated from the liquid electrolyte. It i s
30 therefore preferably placed in a flexible, liquid-tight pouch and stable in contact
with the liquid electrolyte. For example a heat-sealable extruded polyethylene
pouch .
Provision can be made for the compression system 6 to be extractible, thus
making it possible after i t s withdrawal to remove the cathode compartment(s) 2
35 more easily.
The battery 1 can comprise two cathode compartments 2 as described above. In
the case of a battery 1 comprising a metal electrode as negative electrode 3, the
metal electrode 3 in the form of a plate can be compressed between the faces
formed at least partially by an air electrode 22 of the cathode compartments 2.
5 Separators 5 electrically insulate the metal electrode 3 from the air electrodes 22.
As yet another variant, the cathode compartment 2 can comprise two air
electrodes 22, 27 as described above, and the battery 1, two negative electrodes 3
in the form of a plate arranged one on either side of the cathode compartment 2 and
optionally, in the case of a metal electrode, each against a face formed at least
10 partially by an air electrode 22, 27. In the latter case, the cathode compartment 2
can at the same time compress both of the metal electrodes 3 in the same way as
described above.
The cartridge 21 of the cathode compartment 2 can comprise, advantageously
when the negative electrode 3 i s a metal electrode, a rim 28 on i t s face formed at
15 least partially by the air electrode 22, in order to limit the compression of the metal
electrode 3.
In the case in which the metal electrode 3 i s compressed between the cathode
compartment 2 and a wall of the case 11, the cathode compartment 2 compresses
the metal electrode 3 in the direction of the wall of the case 11 until the rim 28
20 comes into contact with the latter.
In the case in which the metal electrode 3 is compressed between two cathode
compartments 2, either a single one of the two compartments 2 has a rim 28, or
both of the compartments 2 have a rim 28. In the first case, the rim 28 will come
into contact with the face of the cartridge 21 of the other cathode compartment 2
25 without a rim, as mentioned above for the rim 28 and the wall of the case. In the
second case, the rims 28 are provided on the faces of the cartridges 21 so as to face
each other, in such a way that the two cathode compartments 2 compress the metal
electrode 3 until the two rims 28 come into contact with each other.
In the case in which the cathode compartment 2 comprises two air electrodes 22
30 at least partially forming opposite faces of the cartridge 21, it may comprise a rim
28 on one of the faces but not the other, or a rim 28 on each of the faces. The rim(s)
act(s) in the same way as described above.
The cathode compartment 2 can comprise a lower part zlNF and an upper part 2SUP,
the lower part zlNF comprising the air electrode(s) 22. The upper part 2SUPh as at
35 least one section perpendicular to the plane of the air electrode below that of the
lower part 21NFT. hus, at the upper part 2S~oPf the cathode compartment 2, a more
extensive space is provided in the case 11 of the battery 1 in order to collect the
liquid electrolyte 4. This allows at the same time a more compact format for the
battery 1. Equally, the additional volume created by the difference in cross section
5 of the upper fsupan d lower 2INF parts of the cathode compartment 2 makes it
possible to avoid the electrolyte 4 rising too high and spilling over during the
charging phase because the release of gaseous oxygen produces bubbles inside the
battery, which raises the level of the electrolyte.
For example, the lower part 2\,.,, has a rectangular shape and the upper part 2sup a
10 trapezoidal shape, in other words, the edges of the upper part are were cut on the
bias, so that the cross section of the upper part 2,up reduces as the distance from the
lower part 2,,, increases. The cross section of the upper part ZSUPc an then remain
constant (see Figure 1 1 ).
In another example, the lower part 21NF and the upper part ZSUPh ave a rectangular
15 shape forming a shoulder at the interface between the two parts 21NF, SUP (see
Figure 12).
The battery 1 can also comprise a second positive electrode 7 for charging the
battery 1 (see Figure 9). This second positive electrode 7 i s preferably arranged
between the negative electrode 3 and the air electrode 2. A separator 5, for
20 example in the form of felt that i s permeable to the liquid electrolyte, can be used
between the air electrode 22 and this second positive electrode 7 and/or the
negative electrode 3 and the second positive electrode 7.
The second positive electrode 7 can also be attached to the cartridge 21 of the
cathode compartment 2 in order to facilitate the insertion or the removal of the air
25 electrode 22 as there is then no need to pay attention to the location of the
insertion of the cathode compartment 2 with respect to the second positive
electrode 7.
The second positive electrode 7 provides protection to the air electrode 22 during
the charging phase of the battery 1. In fact, during the charging phase of the battery
30 1, the air electrode 22 i s disconnected from the positive terminal and the second
positive electrode 7 connected thereto. Thus, during the charging phase, the air
electrode 22 is not used, and the second positive electrode 7 replaces it. It may be .
decided that the air electrode 22 and the second positive electrode 7 are used at the
same time at the start of charging and that only the second positive electrode 7 i s
35 used when the charging voltage i s greater than a given value. Further details relating
to the use of a second positive electrode 7 are given for example in the document
WO 201211 56639.
A spacer 8 can be placed in contact with the second positive electrode 7 in order
to maintain the second positive electrode 7 at a distance from the other elements of
5 the battery so as to facilitate the removal of the oxygen bubbles produced on the
second positive electrode 7 during charging. For example, the spacer 8 i s arranged
between the second positive electrode 7 and the negative electrode 3 andlor
between the second positive electrode 7 and the air electrode 22. This spacer 8 is
permeable to the electrolyte when the latter is liquid. This spacer 8 can be, for
10 example, a plastic grid. The compression pressure on the metal electrode can be
exerted via the spacer 8. As a variant, provision can be made for two spacers 8,
arranged one on either side of the positive electrode 7.
In this case, a mechanical protection 9 that is permeable to the liquid electrolyte,
for example a felt, can be provided between the spacer 8 and the metal electrode 3
15 or the air electrode 22 in order to protect the metal electrode 3 or the air electrode
22 of the spacer.
Generally, the number of possible cathode compartments 2 and that of the metal
electrodes 3 are adapted according to requirements. The only limit imposed is that
each air electrode 2 is coupled to a metal electrode 3 with a separator 5 between
20 them. Illustrative embodiments are described below and can be combined together.
Although these illustrative examples refer to a metal-air battery, the following
paragraphs can easily be adapted to other types of batteries comprising an air
electrode.
In a first embodiment (Figure 5) the battery 1 comprises two cathode
25 compartments 2, each having a single air electrode 22 forming a part of a face of the
cassette 21, and a mechanical reinforcement 26. The battery 1 also comprises a
metal electrode 3. This metal electrode 3 is arranged between the two cathode
compartments 2 so as to be compressed between them.
In a second embodiment (Figure 6)) the battery 1 is identical to the first
30 embodiment with the exception that each of the cathode compartments 2 comprises
a rim 28. These rims 28 are arranged so as to face each other.
In a third embodiment (Figure 7) the battery 1 comprises two cathode
compartments 2, each having a single air electrode 22 forming at least a part of a
face of the cassette 21, and a mechanical reinforcement 26. The battery 1 also
35 comprises a cathode compartment 2, having two air electrode 22 forming at least a
part of two opposite faces of the cassette 21. The battery 1 also comprises two
metal electrodes 3 and four separators 5. The cathode compartments 2, the metal
electrodes 3 and the separators 5 are arranged in the following order: a first cathode
compartment with a single air electrode against a first wall of the case, a first
5 separator, a first metal electrode, a second separator, the cathode compartment
with two air electrodes, a third separator, a second metal electrode, a fourth
separator and finally the second cathode compartment with a single air electrode
against a second wall of the case opposite the first wall.
In a fourth embodiment (Figure 8), the battery 1 is identical to the third
10 embodiment with the exception that it also comprises a compression system 6
arranged after the second cathode compartment 2, between the latter and the
second wall of the case 11.
In a fifth embodiment (Figure 9), the battery 1 is identical to the first
embodiment with the exception that it also comprises two second positive electrodes
15 7. The elements of the battery are arranged inside the case so that they are in the
following order: a first cathode compartment 2 with an air electrode, a first
separator 5, a first second positive electrode 7, a second separator 5, the metal
electrode 3, a third separator 5, a second second positive electrode 7, a fourth
separator 5 and a second cathode compartment 2 with an air electrode.
20 In a sixth embodiment (Figure 10) the battery 1 is similar to the fifth embodiment
except for the fact that the separators have been replaced by assemblies each
comprising a spacer 8 and a mechanical protection 9, the spacer 8 being arranged
against a second positive electrode 7 and the mechanical protection 9 against a
metal electrode 3 or an air electrode 22.

Claims
1. Cathode compartment (2) for an air electrode battery, comprising an air
electrode and is suitable to be inserted into the battery case in an extractible way,
5 in which the air electrode is in the form of a plate, and in which the cathode
compartment (2) is liquid-tight and also comprises an electrical connection (23) for
connecting the air electrode to a positive terminal of a battery, and a hollow
cartridge (21) having an air inlet (24) and an air outlet (25), with at least one flat
face formed at least partially by the air electrode (22).
10
2. Cathode compartment (2) according to claim 1, also comprising a rim (28) on its
face, formed at least partially by the air electrode (22) of the cartridge (21).
3. Cathode compartment (2) according to claim 1 or claim 2, also comprising an
15 additional air electrode (27) in the form of a plate at least partially forming another
face of the hollow cartridge (21), the other face being opposite to the face formed at
least partially by the air electrode (22).
4. Cathode compartment (2) according to one of claims 1 to 3, also comprising a
20 honeycombed mechanical reinforcement (26) arranged inside the cartridge (21)
resting against the air electrode (22).
5. Cathode compartment (2) according to one of claims 1 to 4, having a lower
part (21NF) and an upper part (2SUP),t he lower part @INF)c omprising the air
25 electrode(s) (22, 27) and the upper part (2SUP)h aving at least one section
perpendicular to the plane of the air electrode below the section of the lower part.
6. Rechargeable battery (1) comprising a case (1 1) and inside the latter:
- an air electrode (22);
3 0 - a negative electrode (3); and
- an electrolyte;
in which the air electrode (22) is extractible from the case and incorporated into a
cathode compartment (2) according to one of claims 1 to 5.
7. Battery (1) according to claim 6, in which the negative electrode is a metal
electrode, the electrolyte a liquid electrolyte, and comprising moreover an
electrically insulating separator (5) between the air electrode (22) and the metal
electrode (3) and a flexible element,
5 in which the cathode compartment (2) i s according to one of claims 2 to 6 and
moveable within the case (1 I),
in which the separator (5), the cathode compartment (2) and the metal electrode
(3) are arranged so that the flexible element acts on the cathode compartment (2) so
that it compresses the metal electrode (3) via its face formed at least partiaNy by
10 the air electrode (22).
8. Battery (1) according to claim 7, in which the flexible element i s formed by
the case (1 1 ) or is a compression system (6) arranged against a wall of the case.
15 9. Battery (1) according to claim 7 or claim 8, also comprising a second air
electrode (22) incorporated into a second moveable cathode compartment (2) and
extractible according to one of claims 1 to 7, and a second separator (5) between the
second air electrode (22) and the metal electrode (3),
in which the two cathode compartments (2), the metal electrode (3) the
20 separators (5) and the flexible element are arranged so that the metal electrode (3)
is compressed between the two cathode compartments (2) via their faces formed at
least partially by the air electrodes (22).
10. Battery (1) according to one of claims 6 to 9, also comprising a second
25 positive electrode (7) for charging the battery.
11. Battery (1 ) according to claim 10, in which the second positive electrode (7) is
arranged between the cathode compartment (2) and the negative electrode (3), and
in which the battery (1) also comprises at least one spacer (8) placed in contact with
30 the second positive electrode (7) in order to facilitate the removal of the oxygen
bubbles produced on the second positive electrode (7) during charging.
12. Battery (1 ) according to claim 11, comprising two spacers (8) placed one on
either side of the positive electrode (7).
35
13. Battery (1) according to claim 11 or claim 12, in which at least one spacer (8)
can be provided against a face of the second positive electrode turned towards the
negative electrode (3), respectively towards the air electrode (22),
and also comprising at least one mechanical protection (9) arranged between the
5 spacer (8) and the negative electrode (3), respectively the air electrode (22).