WO2013107619A1

WO2013107619A1 - Energy conversion device having reversible energy storage

Info

Publication number: WO2013107619A1
Application number: PCT/EP2013/000047
Authority: WO
Inventors: Martin Greda; Jeffrey Roth; Bruno Zekorn; Ulrich Rost; Michael Brodmann; Jörg Neumann; Andre Wildometz; Cristian Liviu Mutascu
Original assignee: Westfälische Hochschule Gelsenkirchen Bocholt Recklinghausen; Propuls Gmbh
Priority date: 2012-01-18
Filing date: 2013-01-10
Publication date: 2013-07-25
Also published as: DE102012000755A1

Abstract

The invention relates to a device (1) for converting chemical energy into electrical energy and/or electrical energy into chemical energy, comprising a housing (2) in which at least one electrochemically active cell (3, 4) for performing the conversion is at least partially accommodated. A chemical storage medium (5) in which hydrogen is or can be stored is arranged in the housing (2). The storage medium (5) at least partially encloses the cell (3, 4), has a heat-transferring connection to the cell, and releases hydrogen while absorbing heat from the cell (3, 4) and/or binds hydrogen while outputting heat to the cell (3, 4).

Description

Device for energy conversion with reversible energy storage

The present invention relates to a device for converting chemical energy into electrical energy and / or electrical energy into chemical energy, comprising a housing in which at least one electrochemical cell for carrying out the transformation at least partially rests.

Such devices are as a fuel cell, Elektrolyseurzelle or whole

Units of several such cells known, for example from the German

Patent Application DE 10 2009 057 494 AI, whose contents are hereby incorporated by reference. The active electrochemical cell is one in this case

A fuel cell that converts chemical energy into electrical energy, or an electrolyzer cell that converts electrical energy into chemical energy. The cell is enclosed in a closed housing. The arrangement of several plate-shaped cells in a housing next to each other is called stack, in particular

Fuel cell stack or Elektrolyseurstack called.

In the case of a fuel cell, a fuel and an oxidizer are continuously supplied to the cell. In general, these are oxygen (oxidant) and hydrogen (fuel). The reaction of the two consumables becomes a current

CONFIRMATION COPY E of electrons and thus generates electrical energy. Conventional individual fuel cells generate a low voltage of about 1.2 V, on the other hand, however, a comparatively high current density up to several amperes per

Square centimeter of active reaction area, this area information being related to the size of the active areas in a fuel cell. Since these active surfaces in modern membrane fuel cells, for example, with a polymer electrolyte membrane (PEM) and on both sides of adjacent pole plates more than 100

Square centimeter, a single such fuel cell can deliver a current of several amps and more, with a DC voltage of less than 1.2V. The resulting current is formed from the product of the active area in cm ² and the maximum current density.

Since a DC voltage of less than 1.2 V is too low for many technical applications, in conventional fuel cell units often several cells are connected in series, so that the respective voltages of the cells add up. In addition to the electrical series connection can also be a series circuit of

Supply structure so that the supply of fuel and oxidant to a cell can be simultaneously the discharge of fuel and oxidant from the previous cell. Alternatively, a parallel circuit of

Supply structure be realized. In such an embodiment, particularly compact fuel cell units can be produced.

Conventionally, conventional fuel cells have a flat, planar shape with a substantially rectangular base so that the individual cells can be stacked side by side or one on top of another. This results in a cuboid overall structure whose dimension depends on the number and area of the cells. For the function of a fuel cell, it is necessary for the pole plates to exert a pressure on the polymer electrolyte membrane or a gas diffusion layer arranged between this membrane and the pole plate. Essentially, the pressure causes the necessary electrical contact between pole plates and gas diffusion layers, as well as the electrodes of the membrane, so that in the reaction in the fuel cell electrons are added or removed can. Therefore, a pressure is required inside the housing for the energy conversion, so that the housing must be sealed pressure-tight.

It is an object of the present invention, the efficiency of a

Energy conversion device of the type described above while maintaining their compact design to increase, while their production costs should be low.

This object is achieved by a device having the features of claim 1. Advantageous developments are specified in the subclaims.

According to the invention, a device for converting chemical energy into electrical energy and / or electrical energy into chemical energy is proposed which has a housing in which at least one electrochemical cell for

Carrying out the conversion at least partially rests, wherein in the housing, a chemical storage medium is disposed in which hydrogen is stored or stored, wherein the storage medium surrounds the cell at least partially, is with its heat transferring compound and releasing hydrogen by absorbing heat of the cell and / or releases hydrogen to the cell while releasing heat.

The basic idea according to the invention consists in surrounding the electrochemical cell in a heat-conducting compound by a hydrogen-storing medium which, by absorbing heat from the cell, releases hydrogen in an endothermic process or absorbs hydrogen by releasing heat to the cell through an exothermic process.

The electrochemical cell may be, for example, a fuel cell, a

Elektrolyseurzelle or a conventional battery. The absorption of heat with release of hydrogen is particularly important for the use of the electrochemical cell as a fuel cell, the uptake of hydrogen with the release of heat for the use of the electrochemical cell as electrolyzer cell, why the cell is preferably a fuel cell or a Elektrolyseurzelle. This will be explained below.

Fuel cells operate at different temperature levels, depending on the particular fuel cell type. For example, the temperature range in fuel cells with polymer electrolyte membranes (PEM), for which the present invention is preferably suitable, by 70 ° C (low temperature, in so-called NT-PEM, or about 180 ° C (high temperature) in so-called HT According to the invention, the heat released during the operation of the fuel cell is released to the storage medium surrounding the cell, which consequently releases the hydrogen stored in the storage medium thus acting as a heat sink, thereby reducing the cooling power required to cool the fuel cell and increases the overall efficiency of the fuel cell or the fuel cell unit.

The released from the storage medium as a result of heat absorption hydrogen is supplied to the fuel cell. An additional external supply of hydrogen can be dispensed with. The hydrogen demand for the fuel cell can be provided exclusively from the stored hydrogen in the storage medium. Only one supply line for the oxygen is still required.

When using the electrochemical cell in the inventive

Device as Elektrolyseurzelle result in the same physical

Interdependencies in the opposite direction. In an electrolyzer cell, water is split into hydrogen and oxygen. This requires an electric current, i. electrical energy, as well as a temperature level, which is in the case of using a electrolyzer cell with polymer electrolyte membrane in a similar temperature range, as has been previously stated for the fuel cell. The required heat is generated in the electrolyzer cell. This heat is generated by the power line inside the cell and the ohmic losses associated with it. This is usually a consciously higher voltage at the

Electrolysis cell created so that an "internal" heating of the cell takes place. If hydrogen is supplied to the storage medium, ie conveyed into the housing of the device according to the invention, the storage medium absorbs the hydrogen in an exothermic process. The heat energy released in this case is transferred to the electrolyzer cell, so that less energy is required for the heating. This increases the efficiency of the device when using the electrochemical cell as electrolyzer cell.

The hydrogen uptake process continues as long as the storage medium absorbs hydrogen. Produced excess hydrogen can be filled into an external store. Similarly, in the case of using the electrochemical cell as a fuel cell, the process proceeds as long as that

Storage medium releases hydrogen.

Preferably, in the housing of the device to the at least one required cell another electrochemical cell or two, or more electrochemical cells at least partially einliegen and of the

Be surrounded storage medium. In this way, a whole array of cells can be formed, which obtain hydrogen from the storage medium or store hydrogen in the storage medium. The cells can be flat in design

be formed and arranged parallel to each other, so that the

Overall arrangement forms a stack of cells. This will be a compact

Construction achieved, in addition, there is a largely homogeneous heat distribution.

In one embodiment, all cells of the device may be of similar design. This means that all cells are identical in construction and, in particular, are designed either as fuel cells or as electrolyzer cells, so that the device forms a fuel cell stack or an electrolyzer cell stack.

As already stated, the device according to the invention can have only a single electrochemical cell which operates as a fuel cell. However, it may also include two or more such cells. These can be, for example

be executed plate-shaped and lie next to each other, so that they have a Form fuel cell stack. In a corresponding manner, the device according to the invention can have only a single electrochemical cell, which is known as

Electrolysis cell works. However, it may also include two or more such cells. These, for example, can be designed plate-shaped and lie next to each other, so that they form a fuel cell stack. Since a device with fuel cell (s) and a device with Elektrolyseurzelle (s) in terms of their hydrogen production and their hydrogen consumption complement each other, they can be technically and functionally cooperatively arranged. Thus, with their separate housings, for example, they can be arranged directly adjacent to one another and connected to one another or be such that the electrolyzer cell device supplies the fuel cell device with the hydrogen that it requires. The two housings can be surrounded by an overall housing.

In an alternative embodiment variant of the device according to the invention, at least one of the cells in the housing is a fuel cell and at least one of the further cells is an electrolyzer cell, so that at least two electrochemical cells arranged in the housing are present, each of which

Storage medium are at least partially surrounded. In this structural arrangement, the storage medium thus surrounds both cells simultaneously. This has the advantage that with the electrolyzer cell hydrogen can be enriched in the storage medium, which can be regarded as "charging" of the device, whereas with the fuel cell, the consumption of enriched hydrogen can be done with the release of electrical energy, which in a similar analogy as " Unloading "of the device can be considered. The fuel cell and the electrolyzer cell are thus active at different times.

The energy conversion device thus obtained can be used in a particularly advantageous manner then to convert electrical energy from the electrolyzer cell into chemical energy, which then in the form of hydrogen in the

Storage medium is stored, whereas the fuel cell, this stored chemical energy at a later time back into electrical energy can convert. The device is thus one for energy conversion with reversible energy storage.

A particularly advantageous use of this device is to decentrally store decentrally generated energy, for example from regenerative energy sources, and, if necessary, to make it available at decentralized locations, for example in a vehicle.

The storage medium according to the invention must possess the property in which

Temperature range in which the fuel cell and / or the electrolyzer cell is / are operated to give off hydrogen endothermically or to take up exothermically. As a storage medium in which the hydrogen is already stored, for example, a metal hydride can be used.

The term "hydride" in the narrower sense refers to the binary compounds of metals and some semi-metals with hydrogen, in a broader sense also complex molecules or ionic compounds containing a metal-hydrogen bond

Binding character and their properties, binary hydrides can be classified into the three classes "ionic or salt-like hydrides", "covalent hydrides" and "metallic hydrides." The relevant metallic hydrides, hereinafter called metal hydrides, have metal valence electrons which are both a bond with the

Hydrogen as well as a metallic bond are involved. However, metal hydrides include not only compounds of pure metals with hydrogen, but also metal alloys with hydrogen. These metals or metal alloys absorb at a certain pressure and temperature ratio elemental hydrogen, which is incorporated into the crystal structure of the metal. The result is a brittle compound that can be solved by increasing the temperature or lowering the pressure (desorption). As metal alloys, for example, titanium-iron (TiFe) or lanthanum-nickel (LaNi ₅ ) can be used. The general reaction proceeds in both directions as follows:

Metal / metal alloy + hydrogen <-> metal hydride + heat. Metal hydrides will vary according to their applications

Assigned to temperature ranges. Thus, so-called cryogenic hydrides are known which give off hydrogen in the range of -30 ° C to 80 ° C, medium-temperature hydrides, where this takes place at 80 ° C to 150 ° C, and high-temperature hydrides, in which the hydrogen release at more than 150 ° C. he follows. For each metal hydride there is a certain temperature at which an optimal addition of the hydrogen takes place (absorption). This always occurs with an increase in pressure until a

Saturation concentration is reached. Typical pressure levels are in the range of 1-5 MPa (10 to 50 bar). Such pressure can be in the inventive

Build device inside the housing and compress the electrochemical cells in this way, so that the pole plates exert pressure on the polymer electrolyte membrane or on the arranged between the membrane and pole plate gas diffusion layer. For the delivery of hydrogen from the storage medium, the temperature must then be increased only slightly, i. a small amount of heat are supplied to the storage medium.

Metal hydrides are usually available granulated or powdered, so that their processing, in particular the filling of the metal hydride as a storage medium in the housing of the energy conversion device in a simple manner possible. If the storage medium is formed by a powdery structure or granules, it contains many free areas between the grains, in which unabsorbed gas can accumulate, which inevitably leads to a pressure in the housing interior. The use of a hydrogen-storing or hydrogen storable medium in the housing of the energy conversion device according to the invention thus simultaneously effects the operation of the at least one electrochemical cell

necessary pressure.

Alternatively, as a storage medium in which hydrogen is already stored, a heterocyclic chemical compound can be used. Carbazoles are

heterocyclic compounds, which formally derive from the substance pyrrole by adding two benzo groups. The molecular formula of carbazole is C12H9N. Suitable is Here, for example, the chemical substance 9-ethylcarbazole, which is present at about 70 ° C in liquid form. The loading of the carbazole with hydrogen is exothermic and the discharge endothermic, analogous to metal hydrides.

As already stated, it is necessary for the operation of the device according to the invention as a fuel cell, that in the storage medium is already stored hydrogen, which dissolves during operation of the cell and for the

Combustion process is used in the cell. If only fuel cells are present in the device, or only one fuel cell is present, the hydrogen stored in the storage medium can come from an external source, for example an external electrolyzer cell. In the case of an electrolyzer cell as an electrochemical cell, however, it is necessary that the storage medium such a medium in which the hydrogen can be stored. Thus, in the state of the electrolyzer cell at the beginning of its operation, the storage medium should be hydrogen-free. Therefore, it is advantageous if the

Storage medium for this case is a metal, a metal alloy or a mixture of these substances and is present in particular in powder or granular form, so that it reacts with the hydrogen to form a metal hydride.

In particular, in the case of a device according to the invention with at least one cell, which operates as a fuel cell and at least one further cell, as

Elektrolyseurzelle works, and with a storage medium that surrounds all cells simultaneously, it becomes clear that this storage medium is a substance that two

Memory conditions must have. A first memory state in which no

Hydrogen is stored, and a second memory state in which hydrogen is stored. This physical property is achieved by a metal hydride.

According to the invention, therefore, the storage medium at the beginning of the operation of the device as a fuel cell may be a metal hydride which passes during operation of the fuel cell with elimination of hydrogen (desorption) in the metal hydride forming metal, the corresponding metal alloy or the mixture of metal and metal alloy, and Metal, the metal alloy or the mixture of these in operation the device as electrolyzer cell with absorption of hydrogen (absorption) in the metal hydride passes.

Preferably, the cell or cells are completely surrounded by the storage medium. This has the advantage that an effective and maximum heat transfer from the storage medium to the cell (s) and / or from the cell (s)

Storage medium is reached.

Furthermore, it is advantageous if in the housing a temperature control for

Heating and / or cooling of the storage medium is arranged. Depending on requirements, this temperature control can then be used for additional heating or cooling of the cell or cells. This is especially true for a invention

Energy conversion device useful in the at least one cell

Fuel cell is, so a cooling of the cell is required, and at least one cell is a Elektrolyseurzelle, so a heating of the cell is necessary. Depending on which of the cells is then in operation (fuel or electrolyzer cell), the tempering device can then be used for heating or cooling. This is possible for example by means of a Peltier element, in which only the

Polarity must be reversed.

The device may include lines through which the hydrogen discharged from the storage medium to the fuel cell or fuel cells

Use in their energy conversion process. Alternatively or additionally, the device may comprise lines through which the hydrogen formed by the electrolyzer cell or the electrolyzer cells from the electrolysis of water is supplied to the storage medium. Furthermore, the device can have lines through which the oxygen for the fuel cell is "sucked in." The reaction water formed can also be flushed out via these lines By means of this line, it is also possible to discharge the oxygen which is not required, which is formed during the reaction, for example into the environment outside the housing. Further advantages and features of the invention will be explained with reference to the following description of embodiments with reference to the accompanying figures. Show it:

Figure 1: schematic representation of a device according to the invention with only one electrolyzer cell

Figure 2: schematic representation of a device according to the invention with

only one fuel cell

Figure 3: schematic representation of a device according to the invention with a

Elektrolyseurzelle and a fuel cell

Figure 4: Perspective view of a device according to the invention with a plurality of electrochemical cells

FIG. 1 shows a device 1 according to the invention for converting electrical energy into chemical energy, wherein the chemical energy in the form of hydrogen is stored in the device. The device 1 comprises a housing 2, in which an electrochemical cell 4 is arranged, which operates here as electrolyzer cell. The device 1 thus forms an electrolyzer 1. In this

Electrolysis cell 4, hydrogen is produced by the electrolysis of water. This requires electrical energy and heat energy. The electrical energy is the electrolyzer cell 4 at the electrical terminals 8 by a

Electricity provided. The electrolyzer cell 4 consists of an anode and a cathode, to each of which an electrical line 8 leads. The energy required by the cell 4 results from the reaction equations of the electrolytic decomposition of water of the electrolyzer cell 4 or of the electrolyzer 1, which can be represented by the following implication:

Water + electrical energy + thermal energy - hydrogen + oxygen. As shown in Figure 1, the Elektrolyseurzelle 4 water (H ₂ 0) is supplied. This can be done from a tank, not shown, from the water to

Electrolyzer 1 is pumped. There are formed as reaction products oxygen 0 ₂ and hydrogen H ₂ and a proportion of undissolved water H ₂ 0, all of which are removed from the electrolyzer 4. The derived from the cell 4 hydrogen H ₂ is introduced directly into the housing 2 of the electrolyzer 1 via a line.

As a result, a pressure is generated in the housing. The housing is therefore sealed pressure-tight. An optional hydrogen processing unit 9, which is arranged outside or inside (not shown) of the electrolyzer 1 and serves to purify and / or dry the hydrogen H ₂ coming from the electrolyzer cell 4, may optionally be present.

In the housing 2 of the electrolyzer 1, a powdery or granulated metal alloy 5 is arranged, for example, titanium-iron (TiFe) or lanthanum-nickel (LaNi ₅ ), the hydrogen introduced into the housing 2 H ₂ with release of heat and to form a Metal hydride absorbs. The resulting heat is then delivered to the electrolyzer cell 4, so that the heat energy that must be externally supplied to heat the cell or generated from internal losses, is lower by about the originating from the storage medium 5 amount.

As a rule, due to the internal resistances in the electrolyzer cell, the required heat energy is provided by the cell itself. A synergy effect in the storage of hydrogen in metal hydrides is the transfer of the at

Hybrid formation developed heat, which raises the temperature level and thus the ultimately required electrical energy for heating the

Electrolysis process is reduced. In the energy balance, this increases the electrical efficiency of the electrolyzer. 1

For additionally required heat energy, the device 1 can optionally contain a heater 6, 7 for heating the electrolyzer cell 3, which is arranged in the interior of the housing 2 next to the cell 3. Such a heater is shown schematically in FIG shown in dashed lines. It comprises a heat exchanger 6 and a heat source 7, wherein the heat exchanger 6 and the heat source 7 may be formed as a combined unit, for example in the form of a heating coil or a

Peltier element, the cooling side may abut, for example, on the inside of the housing wall.

The electrolyzer 1 or its cell 4 can be designed in the pocket construction described in DE 10 2009 057 494 A1. As a result, a particularly compact design is achieved.

FIG. 2 shows a device 1 according to the invention for converting chemical energy into electrical energy, wherein the chemical energy in the device is obtained in the form of hydrogen. The device 1 also comprises a pressurized housing 2, in which an electrochemical cell 3 is arranged, which operates here as a fuel cell 3. The device 1 consequently forms a fuel cell 1. In this fuel cell 3, hydrogen H ₂ and oxygen 0 _{2 are} burned to water H ₂ 0. The fuel cell 3 consists of an anode and a cathode, to each of which an electrical line 8 leads. These lines can be removed during operation of the fuel cell 3 at a comparatively low voltage of less than 1.2V, a high current of several amperes. The complete conversion of energy stored chemically in hydrogen into electrical energy is practically impossible in the fuel cell. Heat is always also developed, which is due to the internal ohmic resistance of the cell 3. This is represented by the following implication:

Hydrogen + Oxygen - »Water + Electric Energy + Heat Energy.

The resulting heat loss, which must be dissipated in the prior art for cooling the cell of this, according to the invention for discharging the

Storage medium 5 used that the fuel cell 3 completely surrounds. The

Storage medium 5 is a metal hydride, for example a powdered or granulated hydrogenated metal alloy such as titanium-iron (TiFe) or lanthanum-nickel (LaNi ₅ ). By the Heat of the fuel cell 3, the hydrogen H _{2 is dissolved} out of the metal hydride 5. It is therefore no longer necessary to cool the fuel cell. It is then fed from the housing 2 via a feed line of the fuel cell 3. In this supply line, a valve 10 may be provided to control and / or regulate the amount of hydrogen. Optionally, a particle filter 9 may be present in the supply line in order to purify the hydrogen.

For the initiation of the desorption at the beginning of the process, when the fuel cell 3 is still cold, a heater 6, 7 may be arranged in the housing next to the cell 3, which comprises a heat exchanger 6 and a heat source 7. Preferably, this heating is generally designed as a tempering, which can alternatively also cooling, so that it is able to cool the cell 3, if necessary, if that

Storage medium 5 absorbs less heat energy than the fuel cell 3 generates. Such a temperature control 6, 7 may be formed for example by a Peltier element.

FIG. 3 shows a further embodiment variant of the device 1 according to the invention, in which a fuel cell 3 and an electrolyzer cell 4 are arranged together in the housing 2 and completely surrounded by the storage medium 5. The

Storage medium 5 is a metal hydride, but initially present as a pure metal or metal alloy. To charge the device 1, the first

Operated electrolyzer cell 4, wherein the current for the electrolysis of water can come from renewable energy. The resulting from the water

Hydrogen is introduced into the housing 2 and connects there in an exothermic process with the metal or the metal alloy to said metal hydride 5. This charging process is completed when the metal hydride 5 no further

Can absorb more hydrogen. In this state, the fuel cell can then be operated and supply electricity, which dissolves the hydrogen from the metal hydride 5 again by their heat and burns with the supplied oxygen 0 ₂ . This discharging process takes place until no more hydrogen is released from the metal hydride 5. This can then again through the electrolyzer 4

to be charged. Figures 4 and 5 shows a schematic perspective view of a further variant of a device 1 according to the invention with a plurality of electrochemical cells 3, 4, as described in the German patent application DE 10 2009 057 494 A1. FIG. 4 shows the device 1 in a partially cutaway view.

The cells 3, 4 are designed in a flat design as plates and are parallel equidistant in the cuboid, in particular approximately cube-shaped housing 4 side by side. The arrangement of the cells 3, 4 is such that alternately an electrolyzer cell 4, a fuel cell 3 and a plate-shaped temperature control means 6 are juxtaposed in the same order. As can be seen in FIG. 5, the apparatus comprises three electrolyzer cells 4, three fuel cells 3 and two temperature control plates 6. The two temperature control plates 6 each lie between an electrolyzer cell 4 and a fuel cell 3. In the pressurized housing 2, the metal hydride is used as the storage medium 5 is present, which completely surrounds the cells 3, 4 or the pockets in which they are inserted.

The cells 3, 4 are arranged via supply lines 13 in the bottom plate 12, at whose ends corresponding terminals 11 a, 1 1 b, 1 1 c, 1 1 d, 11e, 1 1 h, 11 i, 11j, with air ( Oxygen), hydrogen and water. Terminal 11 a denotes the air inlet for the fuel cell 3, port 1 1 b the corresponding

Air outlet. Terminal 1 1c denotes the hydrogen inlet for the fuel cell 3, terminal 1 1 d the corresponding hydrogen outlet.

Port 11e indicates the connection for the water inlet at the

Elektrolyseurzellen 4, the corresponding outlet 11 h for water is on the opposite side of the device shown 1. Another connection 1 1j for the hydrogen outlet of the electrolyzer cells 4 is also present on the other side. In the bottom plate 12 is also a line 1 1 i for a so-called dead end of Elektrolyseurzellen 4 available. The electrical connections 8a are connected to the fuel cells 3, the electrical connections 8b to the

Electrolyzer cells 4. Connection 1 1f designates an inlet for the temperature control plate 6, through which a heating or cooling medium can be supplied. A corresponding port 1 1g for the outlet is on the opposite side. The cells 3, 4 are modular in the housing 2 formed in there, not shown pockets used. The device 1 is characterized particularly compact and physically small.

FIG. 6 shows an alternative embodiment to that in FIGS. 4 and 5. It differs from the embodiment in FIGS. 4 and 5 in that the supply lines of the fuel cells 3 and the electrolyzer cells 4 extend on opposite sides of the housing 4. So are the

Supply lines 11 a to 1 1 d for the fuel cell 3, their electrical

Connections 8a and the supply lines 1 1f, 1 1 g for the tempering 6 arranged in the lid 14 of the housing 2. In contrast, the supply lines 1 1e, 11h, 1 1 i and 11 j are provided for the Elektrolyseurzellen in the bottom plate 12. This arrangement has the advantage that structurally all cells can be formed identically, in particular with regard to the position of their supply connections, whereas in the embodiment in FIG. 5 the position of the connections for the fuel cells 3 and for the electrolyzer cells 4 must be different for reasons of space.

For the construction of the device 1 according to the invention in FIGS. 4 to 6, a design is selected that allows a modular introduction of electrochemical cells 3, 4 (fuel cell / electrolyzer) into the housing 2. These cells 3, 4 are introduced from the outside into a pocket located directly in the storage medium 5, i. in the metal hydride. The result is a geometry in which the electrochemical cells 3, 4 are completely surrounded by the metal hydride 5. The built-up in the hydrogen storage 5 pressure compresses the introduced cells 3, 4, which has a positive effect on their properties. By an adapted compression pressure can be

Optimum between electrical contacting of the layers of an electrochemical cell (pole plate, gas diffusion layer »membrane electrode assembly) and the loading of the memory can be achieved.

The metal hydride 5 used is chosen so that the recorded or

amount of heat released (absorption / desorption) to the electrolyzer Fuel cell system is suitable to reduce the one hand, the required electrical energy for water electrolysis or to use the waste heat of the fuel cell 3 for the desorption of hydrogen. In addition, an operating pressure should be selected which ensures optimum compression of these cells 3, 4, occurring

To compensate for temperature differences, are introduced in addition to the electrochemical cells 3, 4 heat exchanger 6 with an intelligent temperature control modular over the pocket system in the housing 2 of the device.

The present invention has described an energy system which

integrated electrochemical cells in an energy storage device with variable pressure level. Electrochemical cells, e.g. Electrolysers or fuel cells or batteries are able to reversibly convert chemical energy into electrical energy. In the case of an electrolyzer fuel cell system, water in the electrolyzer is decomposed into hydrogen and oxygen with the supply of electrical energy and heat, the storage of the hydrogen being e.g. done in a metal hydride storage. From this memory, hydrogen is taken to recover electrical energy by means of a fuel cell under the supply of atmospheric oxygen.

The energy store is designed such that electrochemical cells can be introduced modularly into the storage housing, in which case the cells are completely surrounded by the storage medium. Due to the pressure in the housing 2, the integrated cells are pressed hydraulically / pneumatically. Between the electrochemical cells and the storage medium can be energetically favorable Rekuperationseffekte achieve, u.a. contribute to an increase in system efficiency.

Claims

claims

1. Device (1) for the conversion of chemical energy into electrical energy and / or electrical energy into chemical energy, with a housing (2), in which at least one electrochemical cell (3, 4) for performing the conversion at least partially rests, characterized in that a chemical storage medium (5) in which hydrogen is stored or storable is arranged in the housing (2), wherein the storage medium (5) at least partly surrounds the cell (3, 4) and is in heat-transferring connection with it absorbing heat from the cell (3, 4) and / or releasing hydrogen to the cell (3, 4) while releasing heat.

2. Device (1) according to claim 1, characterized in that the cell (3, 4) is a fuel cell (3).

3. Device (1) according to claim 1, characterized in that the cell (3, 4) is an electrolyzer cell (4).

4. Device according to one of the preceding claims, characterized

in that in the housing (2) one, two or more further electrochemical cell (s) (3, 4) are at least partly inlaid / surrounded by the storage medium (5).

5. Device (1) according to claim 4, characterized in that all cells (3, 4) are similar.

6. Device (1) according to claim 4, characterized in that

at least one of the cells (3, 4) is a fuel cell (3) and at least one of the further cells (3, 4) is an electrolyzer cell (4).

7. Device according to one of the preceding claims 1, 2, 4, 5 or 6, characterized in that the storage medium (5) is a metal hydride or a heterocyclic chemical compound.

8. Device according to one of claims 1, 3, 4, 5 or 6, characterized

characterized in that the storage medium (5) is a metal, a

Metal alloy or a mixture of these is.

9. Apparatus according to claim 6, characterized in that the

Storage medium (5) at the beginning of its operation as a fuel cell (3) is a metal hydride, which passes in the operation of the fuel cell (3) with elimination of hydrogen in the metal hydride forming metal, the corresponding metal alloy or the mixture of metal and metal alloy, and Metal, the metal alloy or the mixture of these in the operation of the device as electrolyzer cell (4) merges with hydrogen into the metal hydride.

10. Device according to one of the preceding claims, characterized

in that the cell (3, 4) or the cells (3, 4) are completely surrounded by the storage medium (5).

1 1. Device according to one of the preceding claims, characterized

characterized in that in the housing (2) a temperature control means (6, 7) for heating and / or cooling of the storage medium (5) is arranged.

12. Device according to one of the preceding claims 2, 4 to 7 or 9 to 11, characterized in that the of the storage medium (5) discharged hydrogen to the fuel cell (3) or the fuel cell (3) is guided for use in their energy conversion process.

13. Device according to one of the preceding claims 3 to 6 or 8 to 11, characterized in that the electrolysis of the cell (4) or the electrolyzer cells (4) from the electrolysis of water formed hydrogen is supplied to the storage medium (5).

14. Device according to one of the preceding claims 6 to 13, characterized

characterized in that in the housing (2) alternately a plate-shaped fuel cell (3) and a plate-shaped electrolyzer cell (4)

are arranged side by side.

15. Device according to one of the preceding claims 6 to 14, characterized

characterized in that between a fuel cell (3) and a

Electrolysis cell (4) a particular plate-shaped temperature control (6) is arranged.

16. Device according to one of the preceding claims 6 to 15, characterized

in that the supply connections (1 1 a, 1 lb, 11 c, 11 d) for the fuel cells (3) or fuel cells (3) and the

Supply terminals (1 1e, 1 1 h, 1 1 i, 11j) for the electrolyzer cell (3) or electrolyzer cells (3) are arranged on opposite sides of the housing (2).