FIELD OF THE INVENTION
The present invention relates to an electrochemical energy and/or voltage and/or current source, especially a metal-air battery or a fuel cell, in which seawater and/or an alkaline solution is usable as electrolyte.
BACKGROUND OF THE INVENTION
Such electrochemical energy, voltage and/or current sources are suited for a number of applications, in which they can be used as energy sources. Examples are ships and other watercraft, electronic devices, toys and the like. Various types of so-called seawater cells are known, which use seawater as electrolyte and which comprise a number of basic components, especially a cathode and an anode. One of the known types of a seawater cell is a magnesium/oxygen battery comprising a magnesium anode, which utilizes seawater as electrolyte as well oxygen dissolved in the seawater as oxidizing agent.
The chemical processes taking place in this cell are the following:
On the anode, magnesium is dissolved according to the equation
2Mg = 2Mg2+ + 4e-.
On the cathode, oxygen is consumed according to the equation
02 + 2H20 + 4e- = 40H-.
Summarizing, this can be described in a simplified manner as follows:

The anode material can be, for example, magnesium, zinc, a mixture of these elements and alloys thereof.

Document US 4,822,698 discloses an energy cell/battery for use in seawater. This battery works according to the aforementioned electrochemical reactions, with magnesium or zinc being used as anode material and an oxygen electrode as cathode. The oxygen supplied to the cathode is dissolved in the seawater. This seawater battery consists of a cylindrical oxygen electrode cathode. The structure comprises single or several anode rods, which contain magnesium or zinc. The oxygen electrode is similar to those used in many ways in other batteries, e.g. in US 6,372,371 Bl. In seawater saturated with air, the disclosed battery is capable of supplying approximately 1.5 volt with 50 mA. The cathode has a size of approximately 800 cm . The battery has a relatively small energy density of about lW/m2.
Document US 5,405,717 discloses a seawater cell, the power of which is slightly increased as compared to that of US 4,822,698. This power increase is caused by the effect of waves, which increases the flow of the seawater through the cathode so as to supply oxygen. The cell structure includes water flow conducting means, which make the water flow through the cell. As seawater contains little oxygen - about 10 g/m on the sea surface and decreasing to lower values depending on the depth and the geographic location - the energy density in this battery, too, is relatively small (1-1.5 W/m ). This energy density is about one hundred times smaller than in classical metal-air cells in the open air.
Document US 5,225,291 discloses a seawater battery, which is operable with or without dissolved oxygen due to the use of a hybrid cathode. The power of this cell is about 50 microampere/cm and 1 - 1.35 volt with dissolved oxygen (about 10 g/m ). The non-oxygen-based cell reactions are observed at cell voltages of about 0.5 volt. This seawater battery is a long-term battery with little output power.
Document US 5,427,871 relates to galvanic seawater cells and batteries, respectively, which use oxygen dissolved in the seawater as oxidizing agent. It is the object of this patent to provide galvanic cells having, as compared to prior cathodes, an improved

cathode structure. This patent discloses a particularly good geometry of the cathode structure in the form of a standard "laboratory bottle brush". This brush has a plurality of thin carbon fibers, which are separated from each other. If the fibers stick together, only the outer surfaces are supplied with fresh oxygen dissolved in seawater. The fibers may be made of any conductive material stable in seawater, e.g. copper or silver alloys, catalyzed stainless steel, titanium and/or carbon. A carbon fiber having catalytic surface modifications is a preferred material for the reduction of oxygen. A carbon fiber cathode disclosed in the patent is produced from a yarn, which includes 3000 fibers having a diameter of 7000 nm. The brush is treated with a solvent and heat. As a whole, the proposed carbon structure is similar to a porous oxygen-carbon cathode.
The cathode brush (30 mm to 150 mm) according to US 5,427,871 is, in one embodiment, surrounded by four magnesium anode rods in a test cell disposed at the surface of the seawater. The load corresponds to 250 mA. The power of the cell (cell voltage versus time (h)) is subject to normal cell voltage drops from 0.8-lVto0.2-0.3V. The cell voltage drops are caused by periods (10 - 20 h) with nearly still seawater. With sufficiently dissolved oxygen, hydrogen peroxide or chlorine and a sufficient seawater salt content this cell outputs approximately 1 volt and current of approximately 0.3 - 0.4 A. In this case, the energy density is at about 0.002 W/cm or 0.003 W/cm .
A battery based on the above principles is described in "Proceedings of the Ocean Drilling program, Initial Reports Volume 191 by Kanazawa, T., Sager, W. W., Escutia, C, et al., 2001. The anode is here an AZ61 magnesium alloy rod having a diameter of 0.184 m and a length of 2.2 m including the anode connecting device. The anode is surrounded by cathode elements, suspended on a titanium frame. The weight of the anode is 120 kg. The weight of the titanium cathode is 40 kg. The cathode elements are made of a titanium wire core with radially arranged carbon fibers.
The obtainable cell voltage is about 1.6 V, although this value is strongly dependent on the conductivity of the seawater, which varies with the temperature and the salt content. The

maximum cell power is limited by the rate at which oxygen is supplied to the cathode. The oxygen supply rate is proportional to the oxygen concentration in the seawater and drops very strongly as the depth increases. In order to obtain the specified output power of 6 W for each cell, a minimum circulation of 20 mm/s, an oxygen concentration of 3 ppm and a salt content of 20 °/00 are necessary. A 24-V DC/DC converter converts the low cell voltage (1.6 V) into an output voltage (24 V). If the cell voltage becomes lower than 1.2 V, the 24-V DC/DC converter becomes inactive until the cell voltage is increased to 1.41 V.
All of the aforementioned batteries/cells suffer from a limited time period with a continuous output power. This is due to voltage drops in the batteries/cells, caused by time periods with nearly stagnant seawater with oxygen dissolved therein by the slow diffusion of oxygen molecules in water (in the air, this process takes place much faster). The transport of oxygen to the surface of the cathode is a reaction step which, accordingly, substantially limits the power of the above-described batteries/cells.
Another galvanic type of seawater batteries, in which normally seawater is used as an electrolyte, comprises a magnesium anode and a cathode of copper chloride or silver chloride. These long-term batteries do not need oxygen dissolved in seawater, but they have a small output energy density, are generally heavy and require a great amount of space. A Mg/CuCl battery with a watt-year as output energy may have a length of 8 Vi feet, a diameter of 9 inches and a weight of approximately 100 pounds. Moreover, these batteries have a limited flexibility with respect to the design and are restricted to a longitudinal shape. Examples are described in US 4,601,961, US 5,288,564, US 6,656,628 B2, which shall be a part of the present application.
Metal-air cells are known primary cells, comprising an anode made of metal, e.g. of aluminum, magnesium or zinc, and an air cathode, which is disposed with a small spacing from the metallic anode, but does not touch the same. A suited electrolyte is provided in a space between the cathode and anode. The anode is immersed into the electrolyte. Different embodiments of such batteries and methods for the production and use of such

batteries are known from the prior art, compare, for example, US 5,004,654, US 5,360,680, US 5,376,471, US 5,415,949, US 5,316,632. Typical metal-air batteries and metal-air fuel cells, respectively, are described, for example, in US 6,127,061. These batteries/fuel cells have good performance characteristics, such as volt/ampere characteristics, power and energy density, flexible design. However, these metal-air cells cannot utilize seawater or be immersed in seawater.
OBJECTS OF THE INVENTION
One of the principle objects of the invention is to develop an electrochemical energy and/or voltage and/or current source, which may specifically serve as an energy source and is preferably usable in seawater, by simultaneously having a flexible design and compatible weight.
STATEMENT OF INVENTION
Accordingly the present invention provides an Electrochemical energy and/or voltage and/or current source, especially fuel cell or battery, wherein seawater (21) and/or an alkaline solution are usable as electrolyte, comprising the following features: at least one anode (2) suited for the use in an electrochemical metal-air cell, at least one, especially plate-shaped, gas diffusion cathode or air cathode (3) having at least one hydrophobic layer, a casing (9), having a casing space (4), especially an interior one, which is limited by one or more liquid-impermeable walls (15, 25 - 30), wherein air or oxygen can be supplied to the casing space (4) through at least one opening (24), at least one (29, 30) of the liquid-impermeable walls (15, 25 - 30) of the casing space (4) is formed, at least partially or region-wise, by the hydrophobic layer of the cathode (3), the anode (2) is spaced apart from the cathode (3) by forming a spacing (13), and is disposed outside the casing space (4), and the spacing (13) between the cathode and the anode (2) is at least partially tillable with an electrolyte (5), especially seawater (21), salt water or an alkaline solution.
BRIEF DESCRIPTION OF THE DRAWINGS
Figs. 1 and 2 show simplified representations of typical metal-air batteries/fuel cells,
comprising one single or a bi-cathode according to the prior art.

Fig. 3 shows a perspective diagonal view of an inverse fuel cell/battery according to the invention.
Fig. 4 shows a sectional view of the battery of Fig. 3, immersed in seawater.
Figs. 5 and 6 show a parallel and series connection of the inverse battery of Fig. 3.
Fig.7 shows a simplified representation of the inverse seawater battery of Fig.3
DETAILED DESCRIPTION OF INVENTION
The primary embodiment of the present invention is Electrochemical energy and/or voltage and/or current source, especially fuel cell or battery, wherein seawater (21) and/or an alkaline solution are usable as electrolyte, comprising the following features: at least one anode (2) suited for the use in an electrochemical metal-air cell, at least one, especially plate-shaped, gas diffusion cathode or air cathode (3) having at least one hydrophobic layer, a casing (9), having a casing space (4), especially an interior one, which is limited by one or more liquid-impermeable walls (15, 25 - 30), wherein air or oxygen can be supplied to the casing space (4) through at least one opening (24), at least one (29, 30) of the liquid-impermeable walls (15, 25 - 30) of the casing space (4) is formed, at least partially or region-wise, by the hydrophobic layer of the cathode (3), the anode (2) is spaced apart from the cathode (3) by forming a spacing (13), and is disposed outside the casing space (4), and the spacing (13) between the cathode and the anode (2) is at least partially fillable with an electrolyte (5), especially seawater (21), salt water or an alkaline solution.
In yet another embodiment the casing, which is especially made of plastics, comprises a frame (15) or a frame-like structure (15), on which the cathode (3) is mounted in a liquid-tight manner.

In still another embodiment the walls (15, 25 - 30) of the casing space (4) form, at least approximately, a cuboid.
In still another embodiment at least two opposite walls (29, 30) of the casing space (4) are formed, at least region-wise, by plate-shaped cathodes (3) or the hydrophobic layers of the plate-shaped cathodes (3), respectively.
In still another embodiment each cathode (3) is assigned a plate-shaped anode (2) on the side facing away from the casing space (4), wherein the plate-shaped anodes (2) are connected, especially detachably, to the casing (4).
In still another embodiment the casing space (4) is supplied with the air or the oxygen through at least one through-hole (24) provided in one of the casing space walls (25).
In still another embodiment the through-hole (24) is arranged in a wall (25) of the casing space (4) not formed by the cathode(s) (3).
In still another embodiment in relation to the destined use of the voltage/current source (8), the through-hole (24) is arranged in the upper region of the walls (15, 25 - 30) of the casing space (4), preferably in the upper side wall (25) of the casing space walls (15, 25 -30) forming a cuboid.
In still another embodiment an air supply line (17), which preferably extends in the upward direction, is connected to the through-hole (24) in a liquid-tight, especially integral manner.
In still another embodiment the air supply line is provided with an air inlet opening (24) at the end opposite the through-hole (14).

In still another embodiment the cathode (3) comprises a gas-permeable hydrophobic layer, a gas-impermeable hydrophilic layer and an electrically conductive element, especially an electrically conductive or current collector layer.
In still another embodiment the walls (15, 25 - 30) of the casing space (4) completely enclose this casing space (4), except the through-hole(s) 14 in the wall(s) (15, 25 - 30).
In still another embodiment the gas-permeable hydrophobic layer is arranged on the side facing the casing space (4) and the gas-impermeable hydrophilic layer is arranged on the side facing away from the casing space (4).
In still another embodiment the electrically conductive or current collector layer, respectively, is arranged between gas-permeable hydrophobic layer and the gas-impermeable hydrophilic layer.
In still another embodiment the gas diffusion cathode or air cathode (3) is formed of plastic-carbon composite materials, especially of thermoplastic carbon composite materials.
In still another embodiment the gas diffusion cathode or air cathode (3) comprises several layers including at least one electrically conductive or current collector layer, respectively, of an inert metal, such as nickel or the like, or of a non-inert metal, such as aluminum or copper or the like, coated with Au, Pt, Ni, Pb or Sn.
In still another embodiment the electrically conductive layer or current collector layer, respectively, is provided with dendritic protrusions.
In still another embodiment the gas diffusion cathode or air cathode (3) comprises a hydrophobic layer and a hydrophilic active layer, which is/are catalyzed by precious metals, such as Pt-Pd or Ag or silver oxide, and/or complex macrocycles or chelates, such as carbon fullerenes or carbon nanotubes.

In still another embodiment a container, e.g. a balloon or a tank, is associated with the electrochemical energy and/or voltage and/or current source, especially with the casing, especially with the casing space (4), which can be filled/is filled with air or gas, wherein the gas can be supplied from at least one opening of the container to the casing space (4), especially to the gas diffusion cathode or air cathode (3).
In still another embodiment the container is arranged inside the casing space (4).
In still another embodiment a DC/DC or DC/AC converter is arranged inside the casing space, especially to adapt the load.
In still another embodiment a supply line through which the air or the gas can be supplied from the container to the casing space (4), especially to the gas diffusion cathode or the air cathode (3).
List of Reference Numbers
1 metal-air battery / fuel cell
2 anode
3 cathode
4 casing space
5 electrolyte
6 side wall
7 bottom wall
8 fuel cell / air-metal battery voltage / current source
9 plastic casing
10 mesh-type layer
11 electric line
12 cable

13 spacing
14 through-hole
15 frame structure
17 air supply line
18 electrode connection
19 negative output
20 positive output
21 seawater
22 load
23 rubber strip tapes
24 through-hole
25 upper wall
26 lower wall
27 side wall
28 side wall
29 side wall
30 side wall
According to the invention, a new structure of an electrochemical energy, voltage and/or current source is provided, especially a metal-air battery/fuel cell, which is operable in various seawater applications and devices. Advantageously, the energy, voltage and/or current source according to the invention is capable of working without problems even if no or too little oxygen is dissolved in the seawater, namely because the energy, voltage and/or current source can be positioned in the seawater in such a way that outer air can be supplied to the cathode(s) through the opening of the casing space. Contrary to the seawater batteries according to the prior art the cathode, therefore, need not use the oxygen dissolved in the seawater for the reduction, but can directly use the oxygen from the air. The inventive energy, voltage and/or current source can, therefore, supply energy almost continuously. Furthermore, the inventive energy, voltage and/or current source is constructed to be environmentally compatible.

The electrochemical energy, voltage and/or current source may comprise a single cell or a plurality of cells and, moreover, additional suited components/ frames/casings/ and devices, such as DC/DC converters or the like. Each cell has an air cathode or air bi-cathodes as interior elements of the casing space, as well as one or more outer anode elements. The respective outer anode element is made of a material selected from the group of aluminum, zinc, magnesium, aluminum alloys, magnesium alloys, zinc alloys and mixtures thereof. The anode is arranged with a small spatial distance from the cathode, that is, it is spaced apart from the same, but does not touch the cathode. Seawater as the electrolyte is provided between the anode and cathode. The outer anode is completely or partially immersed into the electrolyte. A seawater electrolyte is preferred, however, according to the invention, the electrochemical energy, voltage and/or current source can also be operated with an alkaline electrolyte.
The anode is made of a material selected from the group consisting of aluminum, zinc, magnesium and alloys thereof. In addition, effective amounts of additives may be provided ofGa, In, Sn, Cd, Pb.
Preferably, the air/gas diffusion cathode comprises several layers, namely at least one current collector mesh, a gas-impermeable, hydrophilic, active layer with a high-dispersion porous carbon and a gas-permeable, hydrophobic layer.
The casing of the energy, voltage and/or current source, which is especially made of plastics, may comprise one or more frames or frame-like structures, on which the cathodes are each mounted in a liquid-tight manner. In a preferred advancement of the electrochemical energy, voltage and/or current source the walls of the casing space form, at least approximately, a cuboid. As will be appreciated by the person skilled in the art, of course, other shapes are feasible as well. Preferably, at least two opposite walls of the casing space are formed, at least region-wise, by the especially plate-shaped cathodes or the hydrophobic layers of the cathode, respectively.

The casing space can be supplied with the air or the oxygen through at least one through-hole provided in one of the casing space walls. In relation to the destined use of the energy, voltage and/or current source, especially in relation to the positioning thereof in seawater, the through-hole is preferably arranged in the upper region of the walls of the casing space, more preferably in the upper side wall of the casing space walls forming a cuboid. In another embodiment, an air supply line may be provided, which preferably extends in the upward direction and which is connected to the through-hole in a liquid-tight manner, especially integrally, or extends into the same.
In another embodiment of the present invention, a container, e.g. a balloon or a tank, may be associated with the electrochemical energy and/or voltage and/or current source, especially with the casing, especially with the casing space, which can be filled/is filled with air or gas, wherein the air or the gas can be supplied from at least one opening of the container to the casing space, especially to the gas diffusion cathode or the air cathode. In this embodiment, the electrochemical energy and/or voltage and/or current source does not depend on ambient air, whereby the container can preferably be disposed inside the casing space. Moreover, it may be provided to supply the air or the gas from the container to the casing space, especially to the gas diffusion cathode or the air cathode via a supply line.
Additional features of the present invention can be inferred from the appended dependent claims, from the following description of preferred embodiments of the present invention as well as from the appended drawings.
Fig. 1 and 2 show a metal-air battery/fuel cell 1, comprising one single cathode and bi-cathodes 3, respectively. The single and the bi-cathodes 3, respectively, are each arranged and oriented in such a way that their gas-permeable, hydrophobic layers face the open ambient air so as to absorb oxygen for a reduction reaction. In the metal-air battery/fuel cell 1 according to Fig. 1, the single cathode 3 forms together with a side wall 6 and a bottom wall 7 an inner casing space 4, which is filled with an electrolyte 5. An anode 2 is

immersed into the electrolyte 5. In the embodiment of Fig. 2, the side wall 6 is formed by the bi-cathode 3. The single cathode 3 and the bi-cathodes 3, respectively, each have a hydrophilic layer, which is impermeable to gas, on their sides facing the casing space 4.
Fig. 3 shows an inventive electrochemical energy, voltage and/or current source, namely an inverse fuel cell/air-metal battery 8. The energy, voltage and/or current source 8 comprises a substantially rectangular plastic casing 9. The casing 9 is formed by an upper wall 25, a lower wall 26 and side walls 27, 28, 29, 30. The side walls 29, 30 of casing 9 are formed by two planar, plate-shaped cathodes 3. Each of the two cathodes 3 is connected to a frame structure 15 of the casing 9 in a liquid-tight manner, that is, is attached to this structure in a suited way. Each of the two frame structures 15 is, again, integrally connected to the upper and lower walls 25, 26 and side walls 27, 28, or extend into the same, respectively.
The cathodes 3 and the bi-cathode 3, respectively, are air/gas diffusion cathodes. Preferably, each cathode is formed of thermoplastic composite materials and comprises a multi-layer structure. One of these layers is a current collector layer, preferably with dendritic protrusions, selected from an inert metal such as nickel, copper, with a coating of Au, Ni, Pb, Sn or the like. Furthermore, a gas-impermeable, hydrophilic, active layer is provided, which is preferably made of a high-dispersion porous carbon. Moreover, a gas-permeable, hydrophobic layer is provided, preferably of a porous carbon. The hydrophobic layer and the hydrophilic, active layer can be catalyzed by precious metals such as Pt-Pd or Ag or silver oxide and/or complex macrocycles or chelates such as carbon fullerenes or carbon nanotubes. Possibly, a PTFE porous membrane can be used as gas-permeable, hydrophobic layer.
In general, the gas diffusion cathode 3 is similar to an oxygen/air electrode, which is used in standard metal-air batteries/fuel cells in many embodiments, compare US 4,448,856, US 4,885,217, US 5,312,701, US 5,441,823, US 6,127,061, US 6,203,940. These references can be used for the construction of a suitable electrode.

The casing space defined by the walls 25 - 30 and the frames 15, respectively, includes a through-hole 24 on the upper side wall 25. Through this through-hole 24 air or oxygen can be supplied to the casing space 4. An air supply line 17 extends vertically from the upper side wall 25. With one of its ends, the air supply line 17 is connected to the through-hole 24 or extends into the same, respectively. The air supply line allows the deep immersion of the energy, voltage and/or current source 8 into the seawater. In doing so, it is important that the free end of the air supply line 17, which is opposite the casing space 4 and has an opening 14, is disposed above the seawater level. Then, the casing space 4 and thus the cathodes 3 are still supplied with outer air or ambient air through the air supply line.
On the side facing the casing space 4, each of the cathodes 3 has a gas-permeable, hydrophobic layer. On the outer side of each cathode 3, i.e. on the side facing away from the casing space 4, each cathode 3 is provided with a gas-impermeable, hydrophilic, active layer. A mesh-like layer 10 is disposed between the outer and the inner layer of the cathodes, which is connected to an electric line 11, especially an electric cable, which forms the positive electrical connection.
Outside the casing space 4, namely opposite the cathodes 3, plate-shaped anodes 2 are arranged. The anodes 2 are arranged with a small spatial distance from the cathodes 3 to form a spacing 13.
After being run-down, the anode plates 2 can easily be replaced mechanically by new anode plates (charging the battery). The anode matrix material may be formed of metals, which are selected from the group of aluminum, zinc, magnesium and alloys thereof, and can include effective amounts of one or more additives of Ga, In, Sn, Cd, Pb.
Each anode comprises a connection 18, which is connected to electric lines or cables 12, respectively, which form the negative connection.



In this redox process, electrons each flow from the anode 2 via lines 11 and a load 22 and via lines 12 of the pair 19 or 20 to the respective gas diffusion cathode 3, whereby the loads 22 are each separately connected to the outputs 19 and 20.
Fig. 5 shows a parallel arrangement or parallel connection, respectively, of the anodes 2 and the cathodes 3 by connecting in parallel the unipolar lines 11 and 12. An electric circuit connection in terms of a parallel connection has the output voltage of the respective individual cell, while the source impedance is smaller by double the amount. Therefore, the current and the power can be higher by double the amount. In this situation, there is no loss of current.
Fig. 6 shows a connection of the anodes 2 and cathodes 3 in series, wherein the positive line 11 of the output 20, which belongs to the one fuel cell, is connected to line 12 of the output 19 of the second fuel cell. The series connection nearly has double the output voltages due to a smaller current loss by the seawater electrolyte in the very narrow spacing 13.
A simplified view of the inverse seawater battery according to the present invention is illustrated in Fig. 7. The rectangular plastic casing 9 has a size of 9 cm x 5 cm x 2 cm, with the plastic material being polyethylene.
The anode material is made of 99.4 % w/w Al with additions of 0.6 % w/w In, incorporated into the aluminum matrix. The size of the anode plates is 8.5 cm x 4.5 cm x 0.2 cm, and the weight of each plate is 28 g. The anodes 2 comprise the negative electrode connection 18, which is connected to the insulated lines 12 as current collector. The anode plates 2 are loosely fixed to both sides of the casing 9 by means of rubber strip tapes 23. The width of the spacing 13 between the anode plate surface and the gas-impermeable, hydrophilic, active outer layer of the cathodes 3 is 1.5 mm.

The cathode layers of the cathode 3 include an active region for the electrochemical reactions of approximately 64 cm , with 32 cm (4 cm x 8 cm) on each side respectively. The thermoplastic composite cathode layer comprises three layers, such as a hydrophilic active layer, a gas-permeable hydrophobic layer and a current collector mesh. The current collector mesh, namely a nickel mesh, is embedded into a mixture of the hydrophobic and hydrophilic composition, which results in a firm bond of the nickel mesh with the aforementioned layers. The detailed description of the cathode structure as well as the manufacture of the same do not represent a main aspect of this patent.
In a test, the above-mentioned battery was immersed completely into a seawater solution, which had a concentration of 5 % w/w of sea salt per liter of water. The voltage measured in an electric circuit exceeded 1.2 volt for each cell at the outputs 19, 20 in the case of the parallel connection (Fig. 5). In the case of the series connection (Fig. 6), the test battery showed approximately 2.2 volt and supplied continuously and without interruption approximately 1.9 volt with a load of 0.6 ampere as well as 1.4 volt with a load of 1 ampere. The maximum power was approximately 1.8 watt.
With the battery being discharged by 50 %, when the weight of the anodes was reduced by about 50 %, the energy capacity was approximately 70 watt-hours. The power density was approximately 0.03 watt per cm2 of that cathode/anode spacing area that takes part in the electrochemical reaction within the seawater solution. These values exceed the values of prior seawater batteries by 10 times.

WE CLAIM
1. Electrochemical energy and/or voltage and/or current source, especially fuel cell or
battery, wherein seawater (21) and/or an alkaline solution are usable as electrolyte,
comprising the following features:
a. at least one anode (2) suited for the use in an electrochemical metal-air cell,
b. at least one, especially plate-shaped, gas diffusion cathode or air cathode (3)
having at least one hydrophobic layer,
c. a casing (9), having a casing space (4), especially an interior one, which is
limited by one or more liquid-impermeable walls (15, 25 - 30), wherein air or
oxygen can be supplied to the casing space (4) through at least one opening
(24),
d. at least one (29, 30) of the liquid-impermeable walls (15, 25 - 30) of the casing
space (4) is formed, at least partially or region-wise, by the hydrophobic layer
of the cathode (3),
e. the anode (2) is spaced apart from the cathode (3) by forming a spacing (13),
and is disposed outside the casing space (4), and
f. the spacing (13) between the cathode and the anode (2) is at least partially
fillable with an electrolyte (5), especially seawater (21), salt water or an
alkaline solution.
2. Electrochemical energy and/or voltage and/or current source as claimed in claim 1, wherein the casing, which is especially made of plastics, comprises a frame (15) or a frame-like structure (15), on which the cathode (3) is mounted in a liquid-tight manner.
3. Electrochemical energy and/or voltage and/or current source as claimed in claims 1 or 2, wherein the walls (15, 25 - 30) of the casing space (4) form, at least approximately, a cuboid.
4. Electrochemical energy and/or voltage and/or current source as claimed in claims 1, 2 or 3, wherein at least two opposite walls (29, 30) of the casing space (4) are formed, at least region-wise, by plate-shaped cathodes (3) or the hydrophobic layers of the plate-shaped cathodes (3), respectively.

5. Electrochemical energy and/or voltage and/or current source as claimed in one or more of the preceding claims, wherein each cathode (3) is assigned a plate-shaped anode (2) on the side facing away from the casing space (4), wherein the plate-shaped anodes (2) are connected, especially detachably, to the casing (4).
6. Electrochemical energy and/or voltage and/or current source as claimed in one or more of the preceding claims, wherein the casing space (4) is supplied with the air or the oxygen through at least one through-hole (24) provided in one of the casing space walls (25).
7. Electrochemical energy and/or voltage and/or current source as claimed in claim 6, wherein the through-hole (24) is arranged in a wall (25) of the casing space (4) not formed by the cathode(s) (3).
8. Electrochemical energy and/or voltage and/or current source as claimed in claims 6 or 7, wherein, in relation to the destined use of the voltage/current source (8), the through-hole (24) is arranged in the upper region of the walls (15, 25 - 30) of the casing space (4), preferably in the upper side wall (25) of the casing space walls (15, 25 - 30) forming a cuboid.
9. Electrochemical energy and/or voltage and/or current source as claimed in claims 6, 7 or 8, wherein an air supply line (17), which preferably extends in the upward direction, is connected to the through-hole (24) in a liquid-tight, especially integral manner.
10. Electrochemical energy and/or voltage and/or current source as claimed in claims 6, 7, 8 or 9, wherein the air supply line is provided with an air inlet opening (24) at the end opposite the through-hole (14).
11. Electrochemical energy and/or voltage and/or current source as claimed in one or more of the preceding claims, wherein the cathode (3) comprises a gas-permeable hydrophobic layer, a gas-impermeable hydrophilic layer and an electrically conductive element, especially an electrically conductive or current collector layer.
12. Electrochemical energy and/or voltage and/or current source as claimed in one or more of the preceding claims, wherein the walls (15, 25 - 30) of the casing space (4) completely enclose this casing space (4), except the through-hole(s) 14 in the wall(s) (15,25-30).

13. Electrochemical energy and/or voltage and/or current source as claimed in one or more of the preceding claims, wherein the gas-permeable hydrophobic layer is arranged on the side facing the casing space (4) and the gas-impermeable hydrophilic layer is arranged on the side facing away from the casing space (4).
14. Electrochemical energy and/or voltage and/or current source as claimed in one or more of the preceding claims, wherein the electrically conductive or current collector layer, respectively, is arranged between gas-permeable hydrophobic layer and the gas-impermeable hydrophilic layer.
15. Electrochemical energy and/or voltage and/or current source as claimed in one or more of the preceding claims, wherein the gas diffusion cathode or air cathode (3) is formed of plastic-carbon composite materials, especially of thermoplastic carbon composite materials.
16. Electrochemical energy and/or voltage and/or current source as claimed in one or more of the preceding claims, wherein the gas diffusion cathode or air cathode (3) comprises several layers including at least one electrically conductive or current collector layer, respectively, of an inert metal, such as nickel or the like, or of a non-inert metal, such as aluminum or copper or the like, coated with Au, Pt, Ni, Pb or Sn.
17. Electrochemical energy and/or voltage and/or current source as claimed in one or more of the preceding claims, wherein the electrically conductive layer or current collector layer, respectively, is provided with dendritic protrusions.
18. Electrochemical energy and/or voltage and/or current source as claimed in one or more of the preceding claims, wherein the gas diffusion cathode or air cathode (3) comprises a hydrophobic layer and a hydrophilic active layer, which is/are catalyzed by precious metals, such as Pt-Pd or Ag or silver oxide, and/or complex macrocycles or chelates, such as carbon fullerenes or carbon nanotubes.
19. Electrochemical energy and/or voltage and/or current source as claimed in one or more of the preceding claims, wherein a container, e.g. a balloon or a tank, is associated with the electrochemical energy and/or voltage and/or current source, especially with the casing, especially with the casing space (4), which can be filled/is filled with air or gas,

wherein the gas can be supplied from at least one opening of the container to the casing space (4), especially to the gas diffusion cathode or air cathode (3).
20. Electrochemical energy and/or voltage and/or current source as claimed in one or more of the preceding claims, wherein the container is arranged inside the casing space (4).
21. Electrochemical energy and/or voltage and/or current source as claimed in one or more of the preceding claims, wherein a DC/DC or DC/AC converter is arranged inside the casing space, especially to adapt the load.
22. Electrochemical energy and/or voltage and/or current source as claimed in one or more of the preceding claims, wherein a supply line through which the air or the gas can be supplied from the container to the casing space (4), especially to the gas diffusion cathode or the air cathode (3).
23. Electrochemical energy and/or voltage and/or current source, especially fuel cell or
battery, wherein seawater (21) and/or an alkaline solution are usable as electrolyte is
substantially as herein described along with accompanying drawings.
Dated this 21st day of October, 2008.