DE102013013291A1 - Energy storage module with supercapacitors - Google Patents

Abstract

Energy storage module with supercapacitors, each of the supercapacitors is formed from a substantially cuboidal, at least partially deformable capacitor package, which is accommodated in a closed foil bag, several of the supercapacitors are stacked with their respective bottom and top surfaces stacked, each of the supercapacitors at least at one its bottom or top surfaces a cooling plate is assigned, which at least partially corresponds in shape to the shape of the bottom or top surfaces of the supercapacitor, us between the bottom or top surfaces of the supercapacitors and the respective one of the cooling plates, the heat transfer from the bottom or top surfaces the supercapacitor is arranged to the respective cooling plates improving layer.

Description

Background, prior art

An energy storage module with supercapacitors is described below. In particular, it is about an energy storage module for use in electric mobility solutions or Avionikanwengungen.

Whereas until recently lead-acid batteries and nickel-metal hydride batteries were used for hybrid and electric vehicles, current electric cars increasingly use lithium-ion batteries. These offer significant advantages in terms of energy density, reliability, safety, volume and weight. In addition to the lithium-ion batteries are increasingly lithium-polymer batteries for electric vehicles in use.

The range of an electric car so far depends mainly on the capacity and performance of the battery. An increasingly popular alternative to batteries are so-called supercapacitors, which store the electricity electrically instead of electrochemically. Charging time is enormously shortened for supercapacitors, since such a capacitor is fully charged within a few seconds, while for a lithium-ion battery this can take several hours.

So-called super or ultra-capacitors called arrangements are electrochemical or double-layer capacitors, which store electrical energy in two series-connected capacitors each consisting of an electric double layer, which forms between the two electrodes of the capacitor and the ions in electrolytes. The distance in which the charge separation takes place is only a few Angstrom. Highly porous carbon with an internal surface area of up to 2500 m ² / g is usually used as the electrode and, even more so, by the use of nanostructures. Supercapacitors store electrical energy with two different storage principles, static storage in Helmholtz bilayers at the phase boundary between electrode surfaces and electrolyte in a double-layer capacitor, and Faraday charge transfer electrochemical storage using redox reactions on the surfaces of the electrodes in an idealized pseudocondenser. In the case of double-layer capacitors, the proportion of the static double-layer capacitance clearly predominates, while the proportion of faraday pseudo-capacitance is very small. Pseudocapacitors are supercapacitors of predominant pseudocapacity and much less bilayer capacity. Hybrid capacitors have both a large double-layered and a large pseudo-capacitance.

The power density and energy density of supercapacitors is given as kW / kg or as volume power density in kW / cm ³ . They are determined by the heat development at the current load via the internal resistance. High power densities enable applications for buffering consumers (energy storage), which require or give off a high current for a short time (eg recuperation braking). The energy density is the measure of the storable electrical energy. It is given as energy density in Wh / kg or kWh / kg or in Wh / cm ³ or kWh / cm ³ .

Supercapacitors have a high power density, which is reflected in the technically feasible very high charge and discharge currents, as well as long life, reliability, high efficiency and freedom from maintenance. They are therefore suitable for the recuperation of braking energy. In addition, they contain no toxic materials.

The magnitude of the currents flowing during charging and discharging (cycle operation) and the frequency of charging and discharging cycles determine the internal heating of the capacitors. Together with the ambient temperature, this results in the condenser temperature. This is decisive for the life of the capacitors. The changes in the electrical parameters are directly related to the condenser temperature. Cycle operation affects the electrical parameters. For large supercapacitors for power applications with a capacity greater than 1000 F, the short-time maximum current may be greater than 1000 A. At such high currents, a strong internal heating of the capacitors occurs, wherein the thermal expansion forms an additional stress factor. In addition, even strong electromagnetic forces with an effect on the mechanical strength of the electrode-collector connection arise.

The lifetime of supercapacitors depends largely on the operating voltage and the operating temperature. During operation of supercapacitors, the capacity decreases over time and the internal resistance increases. This is due to the heat-induced evaporation of the electrolyte through the seal as well as heat-promoted chemical processes that lead to changes in the properties of the collectors, the electrodes and the electrolyte. The heat development and the internal resistance are linked linearly. A higher internal resistance causes the heat loss to increase, which could lead to an impermissible gas pressure development in the condenser.

The lifetime is approximately doubled per 10 ° K lower operating temperature because the changes in the electrical parameters are correspondingly slower.

The operating voltage also affects the life of supercapacitors. Particularly in the case of supercapacitors whose capacitance results from a very high proportion of redox pseudocapacity, high charge and discharge currents can also cause a corrosion of the collectors. Such processes are accelerated by high temperatures that occur during frequent charging and discharging.

Underlying problem

Based on these problems, the goal is to provide a compact, lightweight, and highly efficient energy storage module with supercapacitors adapted to the needs of electromobility solutions.

solution

In order to achieve this goal, an energy storage module with supercapacitors is proposed, in which each of the supercapacitors is formed from a substantially parallelepiped, at least partially deformable capacitor package, which is accommodated in a closed film pocket. Several of the supercapacitors with their respective bottom and top surfaces are stacked adjacent to each other (over or next to each other). Each of the supercapacitors is associated with a cooling plate at least at one of its bottom or top surfaces, which corresponds in shape at least partially to the shape of the bottom or top surfaces of the supercapacitor. Between the bottom or top surfaces of the supercapacitors and the respective one of the cooling plates, there is arranged a layer which improves the heat transfer from the bottom or top surfaces of the supercapacitors to the respective one of the cooling plates.

Properties and configurations of the energy storage module

On the one hand, the cooling plates cause considerably improved heat dissipation from the supercapacitors, as a result of which the disadvantages of the increased operating temperature described above are at least greatly reduced. By appropriate design of the cooling plates made of aluminum, copper, ceramic (for example aluminum nitride) and the shape of the supercapacitors opposite equivalent shape of the cooling plates, the cooling of the supercapacitors by up to 50% and more compared to only air-cooled arrangements is improved. In addition, the provision of the cooling plates also allows a mechanically more stable, vibration, shock and vibration resistant arrangement of the supercapacitors in the energy storage module. Thus, the stability and the life of the energy storage module can be improved. The heat transfer enhancing layer between the bottom or top surfaces of the supercapacitors equalizes differences between the surfaces of the supercapacitors and the respective ones of the heatsinks. This is significant insofar as the supercapacitors in their film bags are not rigid, but somewhat flexible, and their surfaces, especially the bottom and top surfaces are not flat and thus good heat transfer to the heat sink without this layer is not given.

Such supercapacitors in foil bags are available from the companies, Yunasko from Ukraine (for example Yunasko 1200 F), and JM Energy from Japan (for example JM Energy ultimo 1100 F or 2300 F).

The heat transfer improving layer between the bottom or top surfaces of the supercapacitors and the respective of the cooling plates allows a particularly uniform, area-wide cooling of the supercapacitors, also because it can compensate for any unevenness or deformation of the bottom or top surfaces of the supercapacitors. Thus, the formation of so-called. Hot spots, so local heat ester in the supercapacitors are reduced, which avoids the damage of the supercapacitors by excessive degassing during operation.

In a variant of the energy storage module, the cooling plates protrude laterally beyond the supercapacitors at two mutually opposite edges. Alternatively, in each case three of the cooling plates can enclose two of the supercapacitors, that is, n supercapacitors can be enclosed by n + 1 cooling plates, where n = {1, 2, 3, 4,.

In particular, if the cooling plates are thermally and mechanically coupled to the two mutually opposite edges with a heat sink, there is a very good heat dissipation of the supercapacitors, but also a particularly stable mechanical arrangement.

In a preferred variant, two of the cooling plates in each case hold one of the supercapacitors on its bottom and top surfaces. This allows the supercapacitors to be housed in a solid and rigid enclosure. This enclosure also improves the stability and life of the overall assembly and enhances the overall design Heat dissipation from the supercapacitors across the heatsinks to the heat sink (s).

The heat transfer enhancing layer may comprise a thermal grease, an alumina-bearing silicone, a barium titanate-containing paste, or the like.

The energy storage module can be realized in a variant such that the cooling plates are each connected with their opposite edges to a heat sink, wherein at least one of the heat sinks is flowed through by a cooling fluid. The connection can be implemented by one or more welds, screws, rivets, clamping or plug connections or the like.

The heat sinks may have rectangular areas in contact with the top surfaces of the supercapacitors, from which domed flags extend to angled mounting or end portions.

Brief description of the drawing

Other features, properties, advantages and possible modifications will become apparent to those skilled in the art from the following description in which reference is made to the accompanying drawings.

In 1 a lateral schematic view of an energy storage module is illustrated.

In 2 is a schematic plan view of a supercapacitor of the energy storage module 1 illustrated, wherein the supercapacitor has a substantially cuboidal, at least partially deformable capacitor package, which is accommodated in a closed film pocket.

In 3 is a schematic perspective side view of a stack of supercapacitors of the energy storage module 1 illustrated, wherein the supercapacitors at their bottom or top surfaces are associated with cooling plates, and between the bottom or top surfaces of the supercapacitors and the cooling plates, a heat transfer layer is arranged.

In 4 is a schematic perspective side view of one of the two heat sinks of the energy storage module 1 illustrated.

Detailed description of preferred embodiments

An energy storage module illustrated in the figures 10 has several (in the example twelve) supercapacitors 12 , Their electrical wiring is not further discussed in the present description.

These supercapacitors 12 are formed of a substantially cuboid capacitor pack. This capacitor pack has a plurality of positive electrodes stacked on top of one another and negative electrodes, which are each separated from one another by a separator. Two electrodes each are electrically connected with a conductive electrolyte, an inner conductor. The electrodes are separated by the ion-permeable separator and protected against direct short-circuiting contact. Collectors not further illustrated herein contact the respective positive and negative electrodes and connect them to the positive and negative terminals, respectively. This capacitor pack is in a hermetically sealed foil bag 14 is taken and, since it is formed from a stack of flexible electrode films, at least partially deformable. The foil bag 14 is made of aluminum coated plastic films which are tightly welded together by the action of microwaves.

In the present example the 1 are several of the supercapacitors 12 with their respective floor and top surfaces 12a . 12b arranged stacked adjacent to each other. In each case between two of the supercapacitors 12 is at its bottom or top surface 12a . 12b a cooling plate 16 assigned. The heat sink 16 has an area 18 , the dimensions of the floor and top surfaces 12a . 12b has appropriate dimensions and a rectangular shape, so that in its shape the shape of the floor or top surfaces 12a . 12b of the supercapacitor 12 roughly equivalent.

Between the bottom or top surfaces 12a . 12b the supercapacitors 12 and the respective one of the cooling plates 16 is one of the heat transfer from the bottom or top surfaces 12a . 12b the supercapacitors 12 to the respective one of the cooling plates 16 improving layer 20 is arranged. This layer 20 is a thermal grease, for example, an alumina-bearing silicone, a grease, a barium titanate-containing paste, or the like. This layer 20 has several functions: Firstly, it equalizes unevenness in the surfaces of the supercapacitors relative to the respective heat sink 16 , On the other hand, it improves the heat transfer. Third, it improves the mechanical storage of supercapacitors 12 between the cooling plates 16 , To reduce weight in the presently shown variant, the cooling plates 16 with a central recess 16x Mistake. Instead of a recess 16x can also be provided several strip or lattice-shaped recesses.

The cooling plates 16 tower over at their two opposite short edges 16a . 16b the supercapacitors 12 laterally. Of the ones with the top surfaces 12a . 12b the supercapacitors 12 (about the respective layers 20 ) in contact rectangular areas 18 rich domed flags 24 to angled end sections 26 , The end sections 26 are angled to ensure a good, flat heat transfer and a stable attachment to the heat sinks 18a . 18b to achieve with which the cooling plates 16 thermally and mechanically coupled. These are in the present example of the energy storage module 10 the cooling plates 16 with their opposite edges 16a . 16b at the end sections 26 each with one of the cuboid heat sink 18a . 18b by in the example three screw connections 22 connected. The heat sinks 18a . 18b contain not further illustrated cooling channels and are flowed through in the present example of a cooling fluid, here water or oil.

The arched flags 24 between the rectangular areas 18 and the angled mounting or end portions 26 Practice - depending on the choice of material for the cooling plates 16 - A tension or spring force between the at the cuboid heat sinks 18a . 18b attached end sections 26 and the rectangular areas 18 the cooling plates 16 out. This will be the supercapacitors 12 with the heat transfer improving layers 20 tight between the cooling plates 16 clamped. This also promotes uniform and good heat transfer between the supercapacitors over the area 12 and the cooling plates 16 ,

In the present example, three of the cooling plates each 16 two of the supercapacitors 12 one. The cooling plates are formed in the present variant of aluminum and provide a mechanically stable, mechanically durable arrangement of the supercapacitors in the energy storage module.

The above-described variants of the methods or the devices and their functional and operational aspects serve merely to better understand the structure, the mode of operation and the properties; they do not restrict the revelation to the exemplary embodiments. The figures are partially schematic, wherein essential properties and effects are shown partially enlarged significantly to illustrate the functions, principles of operation, technical features and features. In this case, every mode of operation, every principle, every technical embodiment and every feature which is / are disclosed in the figures or in the text, with all claims, every feature in the text and in the other figures, other modes of operation, principles, technical embodiments and features contained in or arising from this disclosure are combined freely and arbitrarily, so that all conceivable combinations are assigned to the devices described. In this case, combinations between all individual versions in the text, that is to say in every section of the description, in the claims and also combinations between different variants in the text, in the claims and in the figures. Also, the claims do not limit the disclosure and thus the combination options of all identified features with each other. All disclosed features are also explicitly disclosed individually and in combination with all other features herein.

Claims (7)

Energy storage module ( 10 ) with supercapacitors ( 12 ), wherein - each of the supercapacitors ( 12 ) is formed from a substantially cuboidal, at least partially deformable capacitor packet, which in a closed film pocket ( 14 ), - several of the supercapacitors ( 12 ) with their respective bottom and top surfaces ( 12a . 12b ) are stacked adjacent to each other, - each of the supercapacitors ( 12 ) at least on one of its bottom or top surfaces ( 12a . 12b ) a cooling plate ( 16 ) is assigned, the shape of the shape of the bottom or top surfaces ( 12a . 12b ) of the supercapacitor ( 12 ) at least partially, and - between the bottom or top surfaces ( 12a . 12b ) of the supercapacitors ( 12 ) and the respective one of the cooling plates ( 16 ) one the heat transfer from the bottom or top surfaces ( 12a . 12b ) of the supercapacitors ( 12 ) to the respective one of the cooling plates ( 16 ) improving layer ( 20 ) is arranged. Energy storage module ( 10 ) with supercapacitors ( 12 ) according to claim 1, wherein the cooling plates ( 16 ) on two mutually opposite edges ( 16a . 16b ) the supercapacitors ( 12 ) protrude laterally. Energy storage module ( 10 ) with supercapacitors ( 12 ) according to claim 1 or 2, wherein the cooling plates ( 16 ) on two mutually opposite edges ( 16a . 16b ) with a heat sink ( 18a . 18b ) are thermally and mechanically coupled. Energy storage module ( 10 ) with supercapacitors ( 12 ) according to one of claims 1 to 3, wherein in each case two of the cooling plates ( 16 ) one of the supercapacitors ( 12 ) or in each case three of the cooling plates ( 16 ) two of the supercapacitors ( 12 ). Energy storage module ( 10 ) with supercapacitors ( 12 ) according to one of claims 1 to 4, wherein the heat transfer layer ( 20 ) comprises a thermal grease, an alumina-bearing silicone, a barium titanate-containing paste, or the like. Energy storage module ( 10 ) with supercapacitors ( 12 ) according to one of claims 2 to 5, wherein the cooling plates ( 16 ) with their opposite edges ( 16a . 16b ) each with a heat sink ( 18a . 18b ), welded, screwed ( 22 ), wherein at least one of the heat sinks ( 18a . 18b ) is flowed through by a cooling fluid. Energy storage module ( 10 ) with supercapacitors ( 12 ) according to one of claims 2 to 5, wherein the cooling plates ( 16 ) with the cover surfaces ( 12a . 12b ) of the supercapacitors ( 12 ) in contact rectangular areas ( 18 ), of which curved flags ( 24 ) to angled end sections ( 26 ) pass.

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