AU2021374729A9

AU2021374729A9 - Energy storage cell, energy storage device, and method for producing an energy storage cell

Info

Publication number: AU2021374729A9
Application number: AU2021374729A
Authority: AU
Inventors: Peter Biedermann
Original assignee: RUAG Ammotec AG
Current assignee: RUAG Ammotec AG
Priority date: 2019-03-08
Filing date: 2021-07-22
Publication date: 2024-06-27
Also published as: EP4241033A1; WO2020182725A1; DE102019105988A1; CA3198780A1; WO2022096166A1; AU2021374729A1; DE102020129089A1; CN116615632A

Abstract

The invention relates to an energy storage cell comprising an elongated hollow metal container in which a phase change material is arranged and which has at least one open end that is closed in a gas-tight manner by a cover. The energy storage cell has an intermediate manufacturing state, in which the cover is pre-positioned in the metal container such that the phase-change material is prevented from exiting the metal container, and then a manufactured state, in which the cover and the metal container are additionally connected together in a bonded manner in order to permanently close the metal container in a gas-tight manner.

Description

Energy storage cell, energy storage device and method of manufacturing an energy storage cell

The present invention relates to an energy storage cell. In addition, the present invention relates to an energy storage device. Furthermore, the present invention provides a method for manufacturing an energy storage cell.

Known energy storage cells are generally realized as plastic capsules and have a phase change material inside the plastic capsule, which is adjusted in such a way that it changes to the liquid phase when heat is applied endothermicc reaction) and crystallizes again when cooled, thus releasing heat to its environment (exothermic reaction). The generic energy storage cells are mainly used in energy storage systems, which are essentially constructed as follows and function according to the following principle: a plurality of generic energy storage cells are arranged in a tank filled with a liquid, for example water or oil. At a time when there is excess energy, for example during the day when the sun is shining, the excess energy is used to heat the liquid in the tank. In this process, the liquid gives off heat to the energy storage cells so that the phase change material changes to the liquid phase under endothermic reaction. If the liquid in the tank cools down to a phase change material specific phase transition temperature, for example at night, the phase change material crystallizes under exothermic reaction, wherein heat is released or transferred to the liquid.

On the one hand, the energy storage cells must have sufficient sealing to an external pressure of 3 to 4 bar prevailing in the liquid tank. Another sealing aspect, however, is the phase change material arranged inside the energy storage cell. This must therefore also be resistant to chemicals and salts. In general, there is a desire to provide the energy storage cells with as large a surface area as possible, which is then available for heat exchange with the surrounding liquid. For this reason, the energy storage cells were previously manufactured in a spherical or egg-shaped form. The chaotic, uncontrollable arrangement of the energy storage cells in the tank, however, has proven to be a disadvantage. Furthermore, the known energy storage cells are too inert, i.e. the phase transitions of the phase change material as a result of temperature changes are too inert.

From the publication DE 10 2019 105 988 Al of the applicant, a faster-reacting and cheaper-to-manufacture generic energy storage cell is known, which in principle enjoys great popularity. The energy storage cell comprises a closed metal capsule in which phase change material is arranged.

Of critical importance to the safe and long-lasting functionality of the energy storage cell is the fluid-tight sealing of the capsule. The energy storage cell should ensure reliable separation of the phase change material from the environment, namely the fluid, over the lifetime of at least 20 years or 10,000 cycles, reversible exothermic and endothermic reaction. The inventors of the present invention have found that there is potential for improvement in the energy storage cell according to DE 10 2019 105 988 Al from both manufacturing and functional aspects.

It is the task of the present invention to improve the disadvantages from the known prior art, in particular to further develop an energy storage cell as well as an energy storage device in such a way that their fluid sealing is improved and their manufacture is simplified, in particular they are better suited for mass production.

The task is solved by the features of the independent claims.

In accordance with this, an energy storage cell, in particular an accumulator, is provided. The energy storage cell can be set up or arranged, for example in an energy store, in such a way that the energy storage cell is surrounded and/or flowed around by a liquid, such as water, oil or the like. The energy storage cell can function according to the following principle, for example: up to a certain liquid temperature, the energy storage cell absorbs heat, i.e. energy, from the liquid surrounding and/or flowing around the energy storage cell. The energy storage cell is designed to store the absorbed heat or energy. When required, the energy storage cell can release the stored energy again. This can be done, for example, without any control and/or regulating device or external access to the energy storage cell, but preferably exclusively by a temperature sensitivity with respect to the fluid surrounding and/or flowing around the energy storage cell. For example, the energy storage device is a water tank, such as a boiler, which is arranged outdoors and in which the energy storage cell is located. During the day, the water disposed in the water tank may be heated by solar radiation, thereby heating the energy storage cell, which stores the absorbed heat in the form of energy. When the water in the water tank cools down, for example at night, the energy storage cell can release the heat again to warm up the water. The absorption and release of energy can be reversible or repeated as often as required. The energy storage cell is rechargeable and/or designed as an accumulator.

The energy storage cell comprises an elongated, hollow metal container in which phase change material is arranged and which has at least one open end which is sealed gas-tight by means of a lid.

The metal container can be made of metal. The metals used are, for example, aluminium, brass, steel or copper and alloys thereof. Metals are inexpensive and easy to process. In the case of the metal containers according to the invention, it has proved advantageous that metals have a high thermal conductivity. This has made it possible to make a fast-reacting energy storage cell. Due to the increased thermal conductivity of metal, in particular compared to the previously used plastic material, the phase change material reacts significantly faster, in particular more sensitively, to temperature changes in the liquid surrounding and/or flowing around the metal container. Since the thermal conductivity of metals is generally 10 to 1000 factors higher than the thermal conductivity of plastics, the phase change material can react faster by this factor to temperature changes in the liquid. The metal container may have a wall defining a cavity, preferably a storage cavity, wherein in particular the wall serves to separate and/or shield the cavity from its surroundings. The metal container is generally not limited to a particular shape and/or geometry. In this context, the metal container may be designed to be fluid-tight with respect to the environment in such a way that no fluid from the environment can enter the metal container interior and/or no materials arranged within the metal container, such as phase change materials, can escape into the environment.

Phase change materials are generally materials that can store a large part of the thermal energy supplied to them in the form of latent heat. Latent heat is the enthalpy absorbed or released during a first-order phase transition. This means that phase change materials can store a high proportion of heat and/or cold energy and release it as heat in a phase-shifted manner as required. Phase change materials have the advantage of being able to store very large amounts of heat in a small temperature range around the phase change, for example from solid to liquid, or vice versa, gaseous to solid, or vice versa, or from gaseous to liquid. Phase change materials, or rather their energy storage capacities, are based on the utilization of the phase change enthalpy, for example during the solid-liquid phase transition (solidification-melting), or vice versa. Phase change materials may include, for example, salts, for example, Glauber's salt, sodium acetate, or inorganic compounds, for example, kerosenes, fatty acids, or the like. Other exemplary phase change materials include water or metallic phase change materials, such as an aluminum silicon alloy. In general, the phase change material may be selected or adjusted to perform an endothermic reaction when heat is applied and an exothermic reaction when heat is removed. Endothermic reaction is generally understood to mean a reaction in which energy, for example in the form of heat, is absorbed from the environment. The exothermic reaction refers to the opposite, in which energy, for example in the form of heat, is released to the environment, namely the liquid. The absorption and release of energy and/or the phase change can be reversible or repeated as often as desired. According to an exemplary further embodiment of the energy storage cell, the phase change material may be selected and/or adjusted such that it performs an endothermic reaction when heat is supplied and an exothermic reaction when heat is removed. The endothermic reaction and the exothermic reaction may be reversibly executable. The advantage of the energy storage cell is that it can be used not only once but repeatedly, i.e., it can absorb and store energy again after releasing the absorbed and stored energy. According to an exemplary further development, the phase change material can take at least two phases. Further, the phase change material may be adapted to absorb energy upon a phase change from the first phase to the second phase and to release energy upon a reverse phase change from the second phase to the first phase, and/or reversibly transform between the at least two phases. In a further exemplary embodiment, the energy storage cell according to the invention is set up to absorb and store energy from a liquid surrounding and/or flowing around the energy storage cell and, at a predetermined operating point, in particular at a predetermined temperature of the liquid, to release the stored energy, in particular to the liquid. For example, the fluid may be water, oil or the like. According to another exemplary embodiment of the invention, the metal container is made of a metal that is resistant to corrosion and/or salt and/or chemicals, in particular a noble metal or a stainless steel, for example a chromium-nickel steel. It has been found that, on the one hand, resistance to the phase change material arranged within the metal container and, on the other hand, resistance to the liquid surrounding and/or flowing around the metal container may be required. The materials specified have proven to be suitable in this respect.

According to the first aspect of the present invention, the energy storage cell comprises an intermediate manufacturing state in which the lid is pre-positioned in the metal container in such a way that leakage of phase change material from the metal container is prevented, in particular in such a way that the metal container is in particular temporarily sealed in a gas-tight manner, and a subsequent manufacturing state, in particular a final manufacturing state, in which the lid and the metal container are additionally bonded to each other in a material-tight manner for permanently sealing the metal container in a gas-tight manner.

One advantage of the present invention is, among other things, that the energy storage cell can be reliably handled or transported, for example transferred to the subsequent manufacturing station, already in an intermediate manufacturing state in which the phase change material is accommodated in the metal container and is already sealed with respect to the environment, without the energy storage cell already having been completely manufactured and the lid finally being materially connected to the metal container, without phase change material being lost or the desired pressure to be set within the energy storage cell being changed or lost.

The term "temporary" can, for example, be understood to mean that at least until the subsequent material closure manufacturing step, a temporary gas-tightness of the metal container is produced by means of the lid. Furthermore, the term "temporary" can be understood to mean that the gas seal achieved in the production state is not suitable or sufficient for the generic use of the energy storage cell, but is limited to handling or transport steps or periods during the production of the energy storage cell.

For example, a fit between the lid and the metal container may be selected to prevent phase change material from leaking from the metal container. Furthermore, a press fit may be present between the lid and the metal container in the intermediate state of manufacture. Alternatively or additionally, an outer dimension of the lid may be oversized with respect to an inner dimension of the metal container. Furthermore, it is possible that the lid is pressed to the metal container, in particular is pressed therein. In general, it is possible that in the intermediate state of manufacture there is a circumferential gap, in particular an air gap, of less than 0.01 mm between the lid and the metal container. The gap-free abutment of lid and metal container achieved in this way prevents phase change material from leaking out of the container and/or air from entering the interior of the metal container, in particular to maintain a desired pressure ratio within the metal container.

In an exemplary embodiment of the energy storage cell according to the invention, the lid and the metal container are joined together by welding, in particular by laser welding. Welding, in particular laser welding, has proved to be particularly advantageous and effective for generic energy storage cells made of metal, on the one hand to ensure low manufacturing costs, in particular for mass production, and on the other hand to achieve the imperative sealing, in particular gas-tight sealing, against the environment.

In another exemplary embodiment of the present invention, the lid is pre-positioned in the metal container such that the lid and the metal container are flush with each other. For example, the lid may be press-fitted to the metal container, in particular press-fitted therein. For example, the lid can be received inside the metal container, in particular in such a way that an outwardly referred transition between the metal container and the lid is flush, step-free, projection-free, edge-free and/or continuous. This makes it possible to generate a particularly good weld seam, especially a laser weld seam.

In another exemplary embodiment of the energy storage cell according to the invention, the metal container has a longitudinally oriented circumferential edge facing the surroundings at the open end. For example, the metal container has a rotational shape, in particular a hollow cylindrical shape. The peripheral edge may then form an annular surface. Further, the lid may be form-fitted with respect to the peripheral edge such that a circumferential, flush transition is formed between the lid and the peripheral edge. For example, the lid may have a planar base and a ring rim adjacent to the base and projecting from the base, the ring rim being adapted to abut the inner contour of the metal container and to be welded to the metal container. Furthermore, it is possible that the lid has a disc shape, which may be planar, such that a front surface of the metal container is obtained along the complete width extension, i.e. transversely to the longitudinal extension of the elongated metal container, wherein a transition between the lid and the metal container is circumferentially or circumferentially continuously flush, projection-free and/or edge-free.

In accordance with another aspect of the present invention, which may be combined with the foregoing aspects of exemplary embodiments, there is provided an energy storage cell which may be formed, for example, in accordance with any of the aspects and/or embodiments previously described.

The energy storage cell according to the invention comprises an elongated metal container defining a cavity. The metal container can be manufactured or made of metal. The metals used are, for example, aluminum, brass, steel or copper and alloys thereof. Metals are inexpensive and easy to process. In the case of the metal containers according to the invention, it has proved advantageous that metals have a high thermal conductivity. This has made it possible to create a fast-reacting energy storage cell. Due to the increased thermal conductivity of metal, in particular compared to the plastic material used so far, the phase change material reacted significantly faster, in particular more sensitively, to temperature changes of the liquid surrounding and/or flowing around the metal container. Since the thermal conductivity of metals is generally higher by a factor of 10 to 1000 than the thermal conductivity of plastics, the phase change material can react faster by this factor to temperature changes in the liquid. The metal container may have a wall defining a cavity, preferably a storage cavity, wherein in particular the wall serves to separate and/or shield the cavity from its environment. The metal container is generally not limited to a particular shape and/or geometry. The metal container may be designed to be fluid-tight with respect to the environment in such a way that no liquid from the environment can enter the metal container interior and/or no materials arranged within the metal container, such as phase change materials, can leak into the environment.

Phase change material is arranged in the cavity. Phase change materials are generally materials that can store a large part of the thermal energy supplied to them in the form of latent heat. Latent heat is the enthalpy absorbed or released during a first order phase transition. This means that phase change materials can store a high proportion of heat and/or cold energy and release it as heat in a phase-shifted manner as required. Phase change materials have the advantage of being able to store very large amounts of heat in a small temperature range around the phase change, for example from solid to liquid, or vice versa, gaseous to solid, or vice versa, or from gaseous to liquid. Phase change materials, or their energy storage capacities, are based on the utilization of the phase change enthalpy, for example during the solid-liquid phase transition (solidification-melting), or vice versa. Phase change materials may include, for example, salts, for example Glauber's salt, sodium acetate, or inorganic compounds, for example kerosenes, fatty acids, or the like. Other exemplary phase change materials include water or metallic phase change materials, such as an aluminum-silicon alloy. In general, the phase change material may be selected or adjusted to perform an endothermic reaction when heat is applied and an exothermic reaction when heat is removed. An endothermic reaction is generally understood to be one in which energy, for example in the form of heat, is absorbed from the environment. The exothermic reaction refers to the opposite, in which energy, for example in the form of heat, is released to the environment, namely the liquid. The absorption and release of energy and/or the phase change may be reversible or repeated as often as desired. According to an exemplary further embodiment of the energy storage cell, the phase change material may be selected and/or adjusted to perform an endothermic reaction when heat is supplied and an exothermic reaction when heat is removed. The endothermic reaction and the exothermic reaction may be reversibly executable. The advantage of the energy storage cell is that it can be used not only once but repeatedly, i.e., it can absorb and store energy again after releasing the absorbed and stored energy. According to an exemplary further development, the phase change material may take at least two phases. Further, the phase change material may be adapted to absorb energy upon a phase change from the first phase to the second phase and to release energy upon a reverse phase change from the second phase to the first phase, and/or reversibly transform between the at least two phases. In a further exemplary embodiment, the energy storage cell according to the invention is arranged to absorb and store energy from a liquid surrounding and/or flowing around the energy storage cell and, at a predetermined operating point, in particular at a predetermined temperature of the liquid, to release the stored energy, in particular to the liquid. For example, the liquid may be water, oil or the like. According to another exemplary embodiment of the invention, the metal container is made of a metal resistant to corrosion and/or salt and/or chemicals, in particular a noble metal or a stainless steel, for example a chromium-nickel steel. It has been found that, on the one hand, resistance to the phase change material arranged within the metal container and, on the other hand, resistance to the liquid surrounding and/or flowing around the metal container may be required. The specified materials have been found to be suitable in this respect.

The metal container has at least one open end which is sealed in a gas-tight manner by means of a lid. According to the further aspect of the present invention, the lid is shaped such that the lid increasingly wedges with the metal container during axial insertion, in particular pressing, into the cavity. For example, the metal container is rotationally symmetrically shaped. Furthermore, the metal container may have a circumferential wall which bounds the cavity transversely to the longitudinal extent of the metal container. During axial insertion of the lid into the metal container, an outer side of the lid may increasingly wedge with an inner side of the metal container wall. For example, this can be understood to mean that during axial insertion, a normal force acting between the lid and the metal container and acting perpendicularly on the metal container and/or lid increasingly increases. In this way, it can be ensured that the metal container is already sealed, in particular gas-tight, when the lid is inserted into the metal container, in particular without the metal container and the lid already being finally joined to one another, in particular welded, in particular laser-welded. In any case, it can be ensured that phase change material cannot leak out of the metal container into the environment. In this way, handling and transport of the unfinished metal container are possible in a simple manner, wherein loss of the phase change material is excluded.

According to an exemplary further development of the energy storage cell according to the invention, the lid comprises a planar base and a ring rim adjoining the base, which is shaped in such a way that the ring rim increasingly wedges with a circumferential wall of the metal container during axial insertion into the cavity. For example, the ring rim can be connected to the planar base via a predetermined bending or buckling point relative to which the ring rim is bent over during axial insertion, in particular pressing, into the metal container, in particular as a result of the normal force acting between the circumferential wall and the ring rim.

In a further exemplary further development of the energy storage cell according to the invention, the ring rim projects from the plane base in the longitudinal direction of the metal container and is oriented in an angular range of1 to 5, in particular of 30, with respect to the longitudinal axis of the metal container. For example, an outer diameter of the ring rim continuously decreases in the direction of the base. Considered alone, the ring rim may have, for example, a frustoconical shape wherein a longitudinal dimension of the frustoconical shape is substantially smaller in dimension than a transverse dimension thereof.

In a further exemplary embodiment of the energy storage cell according to the invention, the lid has a frustoconical shape. In this case, the lid can basically be formed as a planar disc, wherein a circumferential wall of the disc is curved, resulting in an in particular circumferential cone mantle. The circumferential cone mantle of the lid can be oriented in relation to the longitudinal axis of the lid in an angular range of 1 to 5, in particular of 3.

According to an exemplary further embodiment of the present invention, an outer dimension of the lid is oversized with respect to an inner dimension of the metal container. In this way, on the one hand, a tight closure of the metal container can be achieved and, on the other hand, a wedge can be formed between the lid and the metal container, which can further increase the sealing. For example, there is an interference in the range of 0.04mm to 0.08mm.

According to another aspect of the present invention, which is combinable with the foregoing aspects and exemplary embodiments, there is provided an energy storage cell which may be formed, for example, according to any of the foregoing aspects or exemplary embodiments, as the case may be.

The energy storage cell comprises an elongated, hollow metal container having phase change material arranged therein and having at least one open end.

The metal container can be made of metal. The metals used are, for example, aluminum, brass, steel or copper and alloys thereof. Metals are inexpensive and easy to process. In the case of the metal containers according to the invention, it has proved advantageous that metals have a high thermal conductivity. This has made it possible to create a fast-reacting energy storage cell. Due to the increased thermal conductivity of metal, in particular compared to the plastic material used up to now, the phase change material reacted significantly faster, in particular more sensitively, to temperature changes in the liquid surrounding and/or flowing around the metal container. Since the thermal conductivity of metals is generally a factor of 10 to 1000 higher than the thermal conductivity of plastics, the phase change material can react faster by this factor to temperature changes in the liquid. The metal container can have a wall which delimits a cavity, preferably a storage cavity, wherein in particular the wall serves to separate and/or shield the cavity from its environments. The metal container is generally not limited to a particular shape and/or geometry. In this context, the metal container may be designed to be fluid-tight with respect to the environment in such a way that no fluid from the environment can enter the metal container interior and/or no materials arranged within the metal container, such as phase change materials, can leak into the environment.

Phase change materials are generally materials that can store a large part of the thermal energy supplied to them in the form of latent heat. Latent heat is the enthalpy absorbed or released during a first-order phase transition. This means that phase change materials can store a high proportion of heat and/or cold energy and release it as heat in a phase-shifted manner as required. Phase change materials have the advantage of being able to store very large amounts of heat in a small temperature range around the phase change, for example from solid to liquid, or vice versa, gaseous to solid, or vice versa, or from gaseous to liquid. Phase change materials, or their energy storage capacities, are based on the utilization of the phase change enthalpy, for example during the solid-liquid phase transition (solidification melting), or vice versa. Phase change materials may include, for example, salts, for example, Glauber's salt, sodium acetate, or inorganic compounds, for example, kerosenes, fatty acids, or the like. Other exemplary phase change materials include water or metallic phase change materials, such as an aluminum-silicon alloy. In general, the phase change material may be selected or adjusted to perform an endothermic reaction when heat is applied and an exothermic reaction when heat is removed. An endothermic reaction is generally understood to be a reaction in which energy, for example in the form of heat, is absorbed from the environment. The exothermic reaction refers to the opposite, in which energy, for example in the form of heat, is released to the environment, namely the liquid. The absorption and release of energy and/or the phase change can be reversible or repeated as often as desired. According to an exemplary further embodiment of the energy storage cell, the phase change material can be selected and/or adjusted in such a way that it performs an endothermic reaction when heat is supplied and an exothermic reaction when heat is removed. The endothermic reaction and the exothermic reaction may be reversibly executable. The advantage of the energy storage cell is that it can be used not only once but repeatedly, i.e., it can absorb and store energy again after releasing the absorbed and stored energy. According to an exemplary further development, the phase change material may take at least two phases. Further, the phase change material may be adapted to absorb energy upon a phase change from the first phase to the second phase and to release energy upon a reverse phase change from the second phase to the first phase, and/or reversibly transform between the at least two phases. In a further exemplary embodiment, the energy storage cell according to the invention is arranged to absorb and store energy from a liquid surrounding and/or flowing around the energy storage cell and, at a predetermined operating point, in particular at a predetermined temperature of the liquid, to release the stored energy, in particular to the liquid. For example, the liquid may be water, oil or the like. According to another exemplary embodiment of the invention, the metal container is made of a metal resistant to corrosion and/or salt and/or chemicals, in particular a noble metal or a stainless steel, for example a chromium-nickel steel. It has been found that, on the one hand, resistance to the phase change material arranged within the metal container and, on the other hand, resistance to the liquid surrounding and/or flowing around the metal container may be required. The specified materials have been found to be suitable in this respect.

According to a further aspect of the invention, the open end is sealed gas-tight by press fitting with a lid. The inventors of the present invention have found that the proven press fitting technique is very well suited for the energy storage cells according to the invention in order to ensure sufficient sealing of the metal container in a manner that is simple and inexpensive in terms of production technology and also suitable for mass production, which prevents both leakage of the phase change material from the metal container into the environment and entry of air and/or water from the environment into the interior of the metal container.

In an exemplary embodiment of the present invention, the lid is sleeve-shaped, in particular as a press fitting, and/or telescopically slid onto the metal container and firmly connected to the metal container by means of press fitting. The lid, in particular the press sleeve, can be provided with a sealing element to strengthen the seal between the metal container and the lid. For example, the sleeve defines an opening into which the metal container is inserted. The sleeve wall internal dimension may be adapted with respect to a metal container external dimension, in particular such that there is a gap, especially an air gap, between the metal container and the sleeve of less than 0.01mm. Furthermore, a press fit can be set between the socket inner dimension and the metal container outer dimension.

According to an exemplary further embodiment, a particularly circumferential, axial press length between lid and metal container is at least 10%, in particular at least 20%, 25%, 30%, 35% or at least 40% of a total longitudinal dimension of the metal container.

According to another exemplary embodiment of the present invention, the metal container is formed closed towards one end. For example, the metal container has a cup shape. The cup-shaped metal container is sealed gas-tight at the opposite end by means of the lid. Alternatively, the metal container can be open at both ends, in particular have a tubular shape, and be sealed gas-tight at both open ends by means of a lid. The attachment of lid and metal container for gas-tight sealing of the respective open ends of the metal container can be carried out in accordance with one of the aspects described above or exemplary embodiments. Thus, the energy storage cell according to the present invention is not limited to a particular form of raw material, but may be manufactured on the basis of a tubular or cup-shaped starting material.

According to a further aspect of the present invention, which can be combined with the preceding aspects and exemplary embodiments, an energy storage device, in particular an accumulator system, is provided. The energy storage device may be arranged, for example, to receive and store the excess energy when there is a surplus of energy, and to release the excess energy again when required. The energy storage device is rechargeable and/or designed as an accumulator.

The energy storage system comprises a fluid-tight tank that is at least partially filled with a liquid such as water, oil or the like. The liquid serves essentially as an energy carrier or energy receiver from which or to which energy is delivered or transferred.

According to the invention, at least one energy storage cell, preferably a plurality, in particular several hundreds or thousands of energy storage cells, is arranged in the tank, which are designed according to one of the aspects described above or exemplary embodiments.

According to a further aspect of the present invention which is combinable with preceding aspects and exemplary embodiments, there is provided a method for manufacturing an energy storage cell configured in particular according to one of the aspects or exemplary embodiments described above.

According to the method, an elongated hollow metal container open at at least one end and a lid for closing the open end may be provided. Reference is made to the foregoing with respect to exemplary embodiments of the metal container and lid.

According to the invention, an elongated, hollow metal container is sealed in a gas tight manner at at least one open end by means of a lid by first pressing the lid into the metal container and then joining the lid to the metal container by a material bond.

One advantage of the method according to the present invention is, among other things, that the energy storage cell can be reliably handled or transported, for example transferred to the subsequent manufacturing station, already in an intermediate manufacturing state in which the phase change material is accommodated in the metal container and is already sealed with respect to the environment, without the energy storage cell already having been completely manufactured and the lid finally being materially connected to the metal container, without phase change material being lost or the desired pressure to be set within the energy storage cell being changed or lost.

According to a further aspect of the present invention, which is combinable with the foregoing aspects and exemplary embodiments, there is provided a method for manufacturing an energy storage cell formed in particular according to one of the foregoing aspects or exemplary embodiments.

According to the method, an elongated hollow metal container open at at least one end and a lid for closing the open end may be provided. With respect to exemplary embodiments of the metal container and lid, reference is made to the foregoing.

According to the further aspect of the invention, a lid is increasingly wedged in an elongated, hollow metal container in order to seal the metal container in a gas-tight manner. The wedging can ensure, among other things, that the metal container is already sealed in a gas-tight manner when the lid is inserted into the metal container, in particular without the metal container and the lid already being finally joined to one another, in particular welded, in particular laser-welded. In any case, it can be ensured that phase change material cannot leak out of the metal container into the environment. In this way, handling and transport of the unfinished metal container are possible in a simple manner, wherein loss of the phase change material is excluded.

According to an exemplary further development of the method according to the invention, the method is arranged to produce an energy storage cell according to one of the aspects or exemplary embodiments described above.

Preferred embodiments are given in the sub-claims.

In the following, further properties, features and advantages of the invention will become clear by means of description of preferred embodiments of the invention with reference to the accompanying exemplary drawings, in which show:

Figure 1 a perspective view of an exemplary design of an energy storage cell according to the invention;

Figure 2 a sectional view of the energy storage cell according to Figure 1;

Figure 3 a detailed view of a detail Ill of Figure 2; and

Figure 4 a sectional view of a further exemplary embodiment of an energy storage cell according to the invention.

In the following description of exemplary embodiments of the present invention, an energy storage cell 1 is generally designated by the reference numeral 1. For example, the energy storage cell 1is made of a corrosion-resistant metal.

The energy storage cell 1 comprises the following main components: A hollow cylindrical metal container 3, which according to the exemplary embodiments of Figures 1 to 3 is open on one side and thus forms a cup shape and according to the exemplary embodiments in Figure 4 is open on both sides and has a tubular shape; and a lid 5, by means of which the at least one open end of the metal container 3 is sealed in a gas-tight manner.

Figure 2 shows a sectional view of an exemplary embodiment of a first embodiment of an energy storage cell 1 according to the invention as shown in Figure 1. The metal container 3, which comprises an open end 9 and an opposite bottom 11 viewed with respect to the longitudinal direction L, has a circumferential metal container wall 13, in particular made in one piece, which bounds a cavity 7. The metal wall has, for example, a constant wall thickness. Phase change material (not shown) is arranged within the cavity 7. For exemplary embodiments and the properties of the phase change materials used according to the invention, reference is made to the above description in order to avoid repetition. Exemplarily, the cavity 7 can be occupied between 40% to 60% with phase change material, wherein the filling amount can be adjusted depending on the phase change material to be selected.

As can be seen in particular from the detailed view shown in Figure 3, the lid 5 is made in one piece and has a constant wall thickness. The lid 5 comprises a planar, disc-shaped base 15 and an adjoining ring rim 17 extending substantially in the direction of the longitudinal axis L, which is adapted to come into contact with an inner side 19 of the metal container wall 13. The lid 5, in particular its ring rim 17, and the metal container 3 are flush with respect to each other or merge flush with each other. In other words, there is a continuous transition 21 between the ring rim 17 and the axial end section of the metal container wall 13 without any steps or transitions.

The ring rim can be slightly frustoconical in shape or oriented in its longitudinal extension relative to the longitudinal axis L at an acute angle in the range from 1 to 50, in particular about 30. During axial, telescopic insertion of lid 5 and mantle 3 into one another, the lid 5, in particular its ring rim 17, becomes increasingly wedged with the metal container wall 13. This is also realized, among other things, by an outer dimension of the ring rim 17 being oversized with respect to an inner dimension of the metal container wall 13. Accordingly, the lid 15 is pressed into the metal container 3. On the one hand, this has the advantage that an intermediate manufacturing state is already obtained which already prevents the phase change material from leaking out of the metal container 3. Furthermore, the in particular essentially gap-free abutment of lid 5 and metal container 3 provides an optimum prerequisite for the subsequent material-fluid joining, in particular welding, such as laser welding. The lid 5 can be dimensioned and/or designed in such a way that, during axial pressing into the metal container 3, the ring rim 17 changes its orientation with respect to the longitudinal axis L by being bent radially inwards with respect to a predetermined bending point 23 connecting the ring rim 17 to the base 15. For example, the metal container 33 is made of a material with a higher modulus of elasticity than the material of the lid 5.

Figure 4 shows an alternative embodiment of an exemplary energy storage cell 1 according to the invention. To avoid repetition, the differences arising with respect to the preceding embodiment will be essentially discussed.

One difference between the energy storage cell 1 of Figure 4 and the energy storage cell 1 of Figures 1 to 3 is that the metal container is open on both sides, i.e. in addition to the open end 9 it comprises a further open end 10 opposite the open end 9. Thus the metal container 3 has a rotationally tubular shape which must be sealed gas-tight on both sides to form the energy storage cell.

For this purpose, two in particular identical lids 5 are provided, which differ in several respects from the lid 5 according to the embodiments of Figs. 1 to 3. The lids 5 are rotationally shaped press sleeves which are placed on the metal container from the radial outside and are rigidly fastened to the container by means of press fitting for gas-tight sealing of the container. At the end of the lid 5 arranged on the metal container 3, the lid has a ring bead 27 projecting in the radial direction, i.e. transversely to the longitudinal direction L, in the ring space 29 of which a sealing ring 31is arranged.

An axial circumferential press length is provided with the reference sign a in Figure 4 and amounts to approximately 20% to 25% of a total extension of the metal container 3. The press sleeve 5 according to Figure 4 comprises a cap-shaped form with a closed cap bottom 33, which is oriented substantially perpendicular to the longitudinal direction L and is arranged at an axial distance in longitudinal direction L with respect to a respective face end 35 of the metal container 3. The cap bottom 33 passes by means of a rounded transition 37 into a press shell 39 extending parallel to the longitudinal direction L and thus to the metal container wall 13, at which the press length a is measured.

The features disclosed in the foregoing description, the figures and the claims may be of importance both individually and in any combination for the realization of the invention in the various embodiments.

REFERENCE LIST

1 Energy storage cell

3 Metal container

5 lid

7 cavity

9,10 openend

11 bottom

13 Metal container wall

15 base

17 Ring rim

19 Insidewall

21 Transition

23 Target bend

25 End

27 Ring bead

29 Ring space

31 Ring seal

33 Cap bottom

35 Face end

37 transition

39 Press sleeve

L Longitudinal direction

a Press length

Claims

1. Energy storage cell (1) comprising an elongated, hollow metal container (3) in which phase change material is arranged and which has at least one open end which is closed off in a gas-tight manner by means of a lid (5), wherein the energy storage cell (1) has an intermediate manufacturing state in which the lid (5) is pre-positioned in the metal container (3) in such a way that an escape of phase change material from the metal container (3) is prevented, and a subsequent manufacturing state in which the lid (5) and the metal container (3) are additionally connected to one another in a materially bonded manner for the permanent gas-tight sealing of the metal container.

2. Energy storage cell (1) according to claim 1, wherein the lid (5) and the metal container (3) are connected to each other by means of welding, in particular laser welding.

3. Energy storage cell (1) according to one of the preceding claims, wherein the lid (5) is pre-positioned in the metal container (3) in such a way that the lid (5) and the metal container (3) merge into each other flush.

4. Energy storage cell (1) according to one of the preceding claims, wherein the metal container (3) has at the open end a longitudinally oriented peripheral edge facing the environment and the lid (5) is form-fitted thereto in such a way that a circumferential, flush transition is formed between the lid (5) and the peripheral edge.

5. Energy storage cell (1), in particular according to one of the preceding claims, comprising an elongated metal container (3) which delimits a cavity (7) in which phase change material is arranged, wherein the metal container (3) has at least one open end which is sealed in a gas-tight manner by means of a lid (5) which is shaped in such a way that the lid (5) becomes increasingly wedged with the metal container (3) during axial insertion, in particular pressing, into the cavity (7).

6. Energy storage cell (1) according to one of the preceding claims, wherein the lid (5) comprises a planar base (15) and a ring rim (17) adjoining the base (15), said ring rim (17) being shaped such that the ring rim (17) increasingly wedges with a circumferential wall of the metal container upon axial insertion into the cavity (7).

7. The energy storage cell (1) according to claim 6, wherein the ring rim (17) projects from the planar base (15) in the longitudinal direction of the metal container and is oriented at an angle in the range of 1 to 5, in particular 3, with respect to the longitudinal axis of the metal container.

8. Energy storage cell (1) according to one of the preceding claims, wherein the lid (5) has a truncated cone shape, wherein in particular a circumferential cone shell of the lid (5) is oriented with respect to its longitudinal axis at an angle in the range of 1 to 5, in particular of 3.

9. Energy storage cell (1) according to one of the preceding claims, wherein an outer dimension of the lid (5) is oversized with respect to an inner dimension of the metal container, wherein in particular there is an oversize in the range of 0.04 mm to 0.08 mm.

10. Energy storage cell (1), in particular according to one of the preceding claims, comprising an elongated, hollow metal container (3) in which phase change material is arranged and which has at least one open end which is sealed in a gas-tight manner by means of press fitting with a lid (5).

11. Energy storage cell (1) according to claim 10, wherein the lid (5) is designed in the form of a sleeve, in particular as a press sleeve, and/or is pushed onto the metal container (3) in a telescope-like manner and is firmly connected to the metal container (3) by means of press fitting.

12. Energy storage cell (1) according to one of the preceding claims, wherein the metal container (3) is designed to be closed at one end, in particular has a cup shape, and is sealed in a gas-tight manner at the opposite end by means of the lid (5) or is designed to be open at both ends, in particular has a tubular shape, and is sealed in a gas-tight manner at both open ends by means of a lid (5) in each case.

13. Energy storage device comprising a tank which is sealed in a fluid-tight manner and is at least partially filled with a liquid and in which at least one energy storage cell (1), in particular a plurality of energy storage cells (1), formed in accordance with one of the preceding claims is arranged, wherein in particular a pressure of more than 1 bar, in particular of more than 2 bar, 3 bar or 4 bar prevails in the tank.

14. A method of manufacturing an energy storage cell (1) formed in particular in accordance with one of claims 1 to 12, in which an elongate, hollow metal container (3) is sealed in a gas-tight manner at at least one open end by means of a lid (5) by first pressing the lid (5) into the metal container (3) and then joining the lid (5) to the metal container (3) by a material bond.

15. Method, in particular according to claim 14, for producing an energy storage cell (1) formed in particular according to one of claims 1 to 12, in which a lid (5) is increasingly wedged in an elongated, hollow metal container (3) in order to seal the metal container (3) in a gas-tight manner.

16. Method, in particular according to claim 14 or 15, for manufacturing an energy storage cell (1) formed in particular according to one of claims 1 to 12, in which an elongated, hollow metal container (3) is closed in a gas-tight manner by means of press fitting with a lid (5).

17. The method of one of claims 14 to 16, adapted to manufacture an energy storage cell (1) according to one of claims 1 to 12.