DE102015200700A1 - High-temperature battery - Google Patents

Abstract

The invention relates to a high-temperature battery (1) comprising a battery module (2) which comprises at least one module housing (3) and a plurality of battery cells (4) arranged in the module housing (3). A tempering medium, which serves to dissipate heat from the battery cells (4), is designed as a tempering liquid (5). The module housing (3) has at least one passage (12, 20, 21) for the temperature control liquid (5), via which a receiving space (11) for the temperature control liquid (5) and the at least one module housing (3) are fluidically coupled together.

Description

The invention relates to a high-temperature battery having a battery module which comprises a module housing and a plurality of battery cells arranged in the module housing. A tempering medium serves to dissipate heat from the battery cells.

High temperature batteries are operated in a temperature range between about 150 ° C and about 450 ° C. At lower temperatures, such batteries, which are also referred to as thermal batteries, inactive. Only at the high operating temperatures, an electrolyte or the electrode melt, so that sufficient for the provision of electrical energy transfer of energy between the electrodes is established. The battery cells can be formed, for example, of the sodium sulfur accumulator type (NaS accumulator) or as sodium nickel chloride cells (NaNiCl ₂ cells). In NaNiCl ₂ cells, for example, a solid electrolyte based on a ceramic beta-aluminate is installed, which separates the two half-cells of the respective battery cell. This electrolyte becomes significantly conductive only at elevated temperatures above 150 ° C.

The individual battery cells are usually arranged upright in the module housing and spaced a few millimeters apart, so that the battery cells in the module housing are packed comparatively compact. In the charging and discharging operation, it is advantageous to keep the battery cells at a temperature level that is as constant as possible. Especially the ceramic electrolyte, but also the commonly used TCB seals (TCB = thermal glass bonding, thermal bonding by glass) at the transition of the beta-aluminate ceramic to the metal are sensitive to stress due to both thermal and mechanical stress. Strong thermal alternating loads of the battery cells or dynamic temperature differences along the battery cells, for example during the charging or discharging process thereby lead to an accelerated aging of the same and therefore reduce the life of the high-temperature battery.

In the operation of the battery (charging / discharging) there is a permanent heat release due to irreversible losses, for example, due to internal resistances, which may be both chemically by ion diffusion, as well as electrically. At the same time, during the charging and discharging process, due to the underlying reaction enthalpies of the chemical storage reaction, a superimposed reversible release or formation of reaction heat occurs. However, this effect is lower at higher specific charging and discharging rates than the heat release from irreversible losses. The battery therefore usually has to be deprived of energy during active operation in order to avoid overheating. This can be done by "active cooling" by convection or, if sufficient, by passive heat dissipation into the environment. At standstill or at very low rates of charge and discharge, on the other hand, it is necessary to compensate for thermal losses to the environment due to a thermal insulation which is always limited in its effect.

It is known from the prior art to use air or inert gases as the tempering medium for active cooling. Accordingly, such a high temperature battery has air cooling. However, air cooling is comparatively inefficient due to the low heat capacity and density of gases (typically 1000 times less than that of liquids) when it comes to dissipating heat from the battery cells during operation of the high temperature battery. The same is true when it comes to keeping them in a homogeneous temperature state and (depending on the load profile of the battery) to buffer an irregular heat release.

Object of the present invention is to provide an improved high-temperature battery of the type mentioned.

This object is achieved by a high-temperature battery having the features of patent claim 1. Advantageous embodiments with expedient developments of the invention are specified in the dependent claims.

The high-temperature battery according to the invention comprises a battery module which comprises at least one module housing and a plurality of battery cells arranged in the at least one module housing. A tempering medium for removing heat from the battery cells is designed as a tempering liquid. The at least one module housing has at least one passage for the heat transfer liquid. About the at least one passage, a receiving space for the heat transfer fluid and the at least one module housing are fluidly coupled together.

This is based on the finding that heat can be dissipated from the battery cells during the charging operation or discharge operation thereof in a particularly efficient manner by using a tempering liquid as the tempering medium. However, a volume of possible tempering liquids, which are in the operating temperature range of the high-temperature battery in the liquid phase, increases when heated. This is through the Provision of the additional receiving space for the temperature control taken into account.

The increase in volume of the temperature control liquid thus does not lead to such a pressure increase in the module housing that the battery cells are crushed or otherwise damaged or that the module housing is dented or bursts. On the contrary, the temperature-controlling liquid which expands when heated can escape via the at least one passage into the receiving space. Although liquids are almost incompressible, therefore, no overpressure damaging the battery cells can build up in the module housing. Thus, an improved high-temperature battery is created.

Since the battery cells are preferably surrounded on all sides by the temperature control liquid within the module housing, ie bathing in the liquid temperature control medium, the heat can be dissipated particularly well by the battery cells. This avoids accelerated aging and prolongs the life of the high-temperature battery. Therefore, a particularly economical operation of the high-temperature battery can be ensured.

In particular, the battery may comprise a plurality of module housings, in each of which a plurality of battery cells may be electrically connected in series and / or in parallel. A respective module housing having modules can then in turn be electrically coupled together. The module housings can communicate with a common receiving space or with respective receiving spaces.

In particular, a so-called thermal oil can be used as the tempering liquid, for example in the form of a mineral oil or a synthetic oil, for example a silicone oil. With such commercially available thermal oils results in a heating of 25 ° C to 300 ° C an increase in volume of about one third of the cold volume of the thermal oil. By providing the fluidically coupled to the module housing receiving space even such an increase in volume of the thermal oil does not lead to the occurrence of a battery cell damaging overpressure within the module housing or an unwanted escape of thermal oil from the module housing.

In principle, it is possible to compensate for the additional volume to be absorbed during the heating of the bath liquid by passing the excess liquid volume resulting from the heating over a pipe or the like into a reservoir which is open to the surroundings of the module housing. By providing such a surge tank, which is open to the ambient air, it can be achieved that the pressure in the module housing does not rise above the ambient pressure. Such a high-temperature battery is thus pressure-free.

In such an open system, however, the bath liquid is exposed to the ambient air in the expansion tank. The contact with oxygen in turn has a negative effect on the life of many tempering liquids (for example commercially available thermal oils). This aging effect increases exponentially with the increase of the temperature of the tempering liquid at the contact surface to the oxygen (for example, from the ambient air).

If thermal oil is used as the bath liquid, cooling of the expansion tank is required. Otherwise, the thermal oil would react above about 200 ° C with the atmospheric oxygen. In particular, it may then lead to a coking of the thermal oil, which impairs the functionality of the thermal oil. For a stationary operated high-temperature battery, the cooling of the expansion tank can still be realized comparatively easily and is thus practicable.

In particular, however, when the high-temperature battery is to be used for mobile applications, among other things, the compactness of the high-temperature battery is gaining in importance. At the same time sloshing of the liquid level, in particular thermal oil level, among other things, for safety reasons as possible to avoid. Such a sloshing can be caused by the movement in a mobile application of the battery and thus have a possible emission of the bath liquid result. An over spilling of the temperature control liquid can also be caused by a simple unwanted displacement of the center of gravity of the expansion tank.

A hermetically closed operation of the battery is therefore to be preferred.

In a preferred embodiment of the invention, therefore, the receiving space is closed to an environment of the module housing and has a variable volume. In such, to the environment of the module housing towards hermetically sealed receiving space, a contact of the bath with ambient air is prevented. Such a hermetically sealed receiving space (apart from the at least one passage to the module housing) does not require any elaborate cooling, as required by the provision of an expansion tank open to the environment. Therefore, by the high-temperature battery with the closed receiving space, which prevents contact of the bath with the ambient air, a particularly large compactness achievable.

Furthermore, no connections for the tempering need to be provided to the outside. Rather, only a fluidic coupling of the receiving space with the module housing via the at least one passage is sufficient to allow the temperature control liquid to enter the receiving space. Such a high-temperature battery provides increased security against leakage of heat transfer fluid. This is particularly advantageous when the heat transfer fluid is a thermal oil, since contamination of the environment with the thermal oil can thus be largely avoided.

In addition, such a compact high-temperature battery with a closed receiving space is characterized by a particularly simple installation, which simplifies the replacement of the high-temperature battery for repair or service purposes.

Furthermore, associated with the cooling of an open surge tank standby losses. In fact, cooling power does not have to be applied in order to keep the heat transfer liquid in an expansion tank well below 200 ° C., as in an open system.

As a result of the hermetically closed operation of the high-temperature battery, the temperature-control liquid is thus sealed off from the environment and thus an access of atmospheric oxygen to the temperature-control liquid is avoided. This reduces degradation due to atmospheric oxygen of the bath liquid during operation. This makes it possible to achieve a particularly long service life of the bath fluid.

This is especially true when a thermal oil is used as the bath liquid. In particular, when operating the high-temperature battery at temperatures close to the operating limit of the high-temperature battery can be about 50 times to 100% increase the useful life of a thermal oil when access of atmospheric oxygen is inhibited to the thermal oil.

The receiving space can be provided for example by a diaphragm bellows. Such a diaphragm bellows as an expansion vessel or expansion element provides an additional volume even at low overpressures of the bath liquid by expansion and thus prevents the battery cells from being damaged. By connecting a diaphragm bellows to the module housing filled with the temperature control fluid, in particular the thermal oil, the module housing breathes when heated and cooled, without relevant overpressures forming inside the module housing. This makes it particularly easy to avoid mechanical damage to the battery cells.

Preferably, the membrane bellows is arranged on the module housing in such a way that the force of gravity promotes a movement of the receiving space from a first state with a first volume to a second state with a second, lower volume. The diaphragm bellows can be arranged for this purpose, for example, with respect to the direction of gravity at an upper side of the module housing. Then, the force of gravity acts on an upper-side wall of the diaphragm bellows and assists in contracting the diaphragm bellows during cooling of the temperature-control fluid. This makes it particularly easy to provide the receiving space with the variable volume.

As further advantageous, it has been shown that the high-temperature battery comprises at least one spring element, by means of which a reduction in the volume of the receiving space is effected. Accordingly, then an increase in volume of the receiving space takes place against the force of the at least one spring element, when the bath liquid heated. On cooling the tempering liquid, on the other hand, the at least one spring element assists in reducing the volume of the receiving space. This makes the high-temperature battery particularly reliable.

Additionally or alternatively, the receiving space may be provided by a strain cell. In such a strain cell membrane-like walls may be connected to each other at the periphery, which limit the receiving space. Also, such a Dehnzelle can be particularly easily provide a closed to the environment of the module housing receiving space with a variable volume.

As a further advantage, it has been shown that the receiving space limiting walls are arranged within a chamber, which is arranged on the module housing. Thus, a volume occupied by the chamber and the module housing remains unchanged, even if the volume occupied by the bath fluid changes. This simplifies the handling of the high-temperature battery, and in particular the possibility of installing the high-temperature battery at a desired location of a plant, a vehicle or the like.

Preferably, the chamber and the module housing are surrounded by an insulating material. So will ensured that the necessary for the operation of the high-temperature battery temperature can be maintained particularly easily.

Also, a plurality of the chambers and a plurality of module housings of the high-temperature battery may be surrounded by an insulating material.

As a further advantage, it has been shown, if at least one wall of the receiving space is flexible. This can for example be accomplished by the wall is made of a thin-walled metal, the profiling allows a change in volume of the receiving space. Additionally or alternatively, at least one wall of the receiving space may be formed of an elastic material to provide the variable volume.

It is also advantageous if at least one wall of the receiving space is formed from a steel and / or an aluminum alloy. Namely, such a material is particularly simple in meeting the requirements for resistance to the operating temperatures of the high-temperature battery. In particular, it can be provided that the metallic walls of the receiving space are up to temperatures of about 450 ° C resistant.

Furthermore, metals such as, in particular, steel and / or aluminum have a sufficient resistance to thermal oil as a tempering liquid. Also, therefore, the use of these materials for providing the at least one wall of the receiving space is preferred.

Finally, it has proven to be advantageous if the volume of the receiving space has a maximum size with an increase in the pressure of the bath liquid of about 200 mbar. This ensures that the receiving space increases its volume even with a particularly small increase in the pressure of the bath liquid. Furthermore, this pressure is well below the pressure for which battery cells of high temperature batteries are usually designed.

For example, the cell housings of the battery cells of a sodium nickel chloride battery consist of thin-walled metal sheets with a wall thickness of 0.3 millimeters. Such battery cells are designed so that they can withstand a pressure of up to about 500 mbar. Accordingly, the receiving space preferably ensures that the pressure exerted by the bath liquid on the battery cells overpressure is less than 500 mbar.

The features and feature combinations mentioned above in the description as well as the features and feature combinations mentioned below in the figure description and / or shown alone in the figure can be used not only in the respectively specified combination, but also in other combinations or in isolation, without the scope of To leave invention. Thus, embodiments are also included and disclosed by the invention, which are not explicitly shown or explained in the figure, however, emerge and can be produced by separated combinations of features from the embodiments explained.

Further advantages, features and details of the invention will become apparent from the claims, the following description of preferred embodiments and from the drawing.

Here, the figure shows schematically a high-temperature battery with a module housing, which encloses a plurality of battery cells, wherein in a chamber adjacent to the module housing a receiving space for a thermal oil is provided, which has a variable volume.

A high-temperature battery shown in the figure 1 includes a battery module 2 with a module housing 3 and with a plurality of battery cells 4 , which in the module housing 3 are arranged. The high temperature battery 1 can, for example, battery cells 4 of the type sodium nickel chloride (NaNiCl ₂ ) or sodium sulfur (NaS). Such battery cells 4 are operated in a temperature range between 150 ° C and 450 ° C.

The individual battery cells 4 have a respective cell housing made of thin-walled sheet metal and are within the module housing 3 present standing upright. In spaces between the battery cells 4 as well as between the battery cells 4 and walls of the module housing 3 is a tempering liquid, preferably in the form of a thermal oil 5 , From the walls of the module housing 3 which the battery cells 4 the high-temperature battery 1 encloses all sides, are in this case a bottom plate 6 , a first sidewall 7 , a second side wall 8th and a top wall 9 shown.

When heated turns on the thermal oil 5 an increase in volume. This can be at a heating of 25 ° C to 300 ° C about one third of the volume, which is the thermal oil 5 at 25 ° C occupies. In order for this extra volume of thermal oil 5 Make room without putting on the cell case of the battery cells 4 applied pressure is too high, is at the high-temperature battery 1 for example through a diaphragm bellows 10 one accommodation space 11 for the thermal oil 5 provided. The recording room 11 , which is inside the diaphragm bellows 10 is formed, is through a passage 12 with the interior of the module housing 3 fluidly coupled. Accordingly, through the passage 12 thermal oil 5 from the module housing 3 in the recording room 11 enter.

Characterized in that a volume of the diaphragm bellows 10 zoom in and out, the diaphragm bellows 10 So having a variable volume, the fact can be taken into account that the thermal oil 5 when heated and cooled each occupies a different volume. An inflow of thermal oil 5 in the diaphragm bellows 10 during heating or from the diaphragm bellows 10 in the module housing 3 when cooling the thermal oil 5 is in the figure by a double arrow 13 illustrated.

The diaphragm bellows 10 or such an expansion body or such an expansion vessel provides a sufficiently large receiving space 11 ready to absorb the volume of oil resulting from heating the thermal oil 5 to the maximum operating temperature of the battery cells 4 established.

In addition, an additional volume is already at low pressures of the thermal oil 5 provided. This prevents the battery cells 4 due to the volume increase of the thermal oil 5 to be damaged.

The cell case of the battery cells 4 can consist of thin-walled sheets which withstand a pressure of up to about 500 mbar. Accordingly, the diaphragm bellows 10 or such a thin-walled metal expansion body such as steel or aluminum is preferably designed to reach its maximum extent in the range of about 200 mbar. The formation of the diaphragm bellows 10 Made of metal such as steel or an aluminum alloy also ensures a durability of the diaphragm bellows 10 relative to the temperature control, in this case the thermal oil 5 , and to temperatures of preferably up to about 450 ° C.

Since the diaphragm bellows 10 to an environment of the module housing 3 hermetically closed, is a contact of the thermal oil 5 suppressed with atmospheric oxygen. Accordingly, a degradation of the thermal oil 5 slowed down. Furthermore, does not need like an open expansion tank, the thermal oil 5 cooled to less than 200 ° C to coking the thermal oil 5 to avoid. In addition, it points to the passageway 12 to the module housing 3 hermetically sealed diaphragm bellows 10 no further oil connections to the outside. This increases the safety against oil leakage.

The passage 12 is present in the upper wall 9 of the module housing 3 shown trained. Accordingly, the diaphragm bellows 10 on the top side of the module housing 3 arranged. Accordingly, the supports on an upper wall 14 of the diaphragm bellows 10 acting gravity the contraction of the diaphragm bellows 10 when cooling the thermal oil 5 , bellows 26 of the diaphragm bellows 10 , which on the upper wall 14 of the diaphragm bellows 10 are adjacent, are flexible and thus allow the increase in volume of the diaphragm bellows 10 ,

In the present case is the diaphragm bellows 10 within a chamber 15 arranged, which to the module housing 3 borders. Between an upper wall 16 the chamber 15 and the upper wall 14 of the diaphragm bellows 10 are present compression springs 17 arranged, which may be provided if the diaphragm bellows 10 when cooling the thermal oil 5 does not reform enough by itself. The compression springs 17 namely, are designed to reduce the volume of the receiving space 11 to effect. double arrows 18 illustrate increasing or decreasing the volume of the receiving space 11 when the top wall 14 of the diaphragm bellows 10 to the upper wall 16 the chamber 15 towards or from the upper wall 16 the chamber 15 moved away.

Additionally or alternatively to the diaphragm bellows 10 can, as shown here by way of example, the receiving space 11 for the thermal oil 5 through a strain cell 19 be provided. The recording room 11 the expansion cell 19 In the present case, at least one, preferably two, passages against the background of a lighter initial filling 20 . 21 with the interior of the module housing 3 fluidly coupled. Accordingly, when heating the thermal oil 5 the thermal oil 5 over the passages 20 . 21 in the recording room 11 the expansion cell 19 flow in or during cooling of the thermal oil 5 from the recording room 11 the expansion cell 19 flow out.

The flow of thermal oil 5 over the passages 20 . 21 in the recording room 11 into or out of the recording room 11 Out is illustrated in the figure by further double arrows. The expansion cell 19 contains from the beginning a certain amount of thermal oil 5 However, it is before the inflow of more thermal oil 5 not yet bulging. When volume increase of the thermal oil 5 the expansion cell bulges 19 off, at volume decrease, the Dehnzelle pulls 19 together again.

A deformation of walls 22 the expansion cell 19 is in the figure by more double arrows 23 illustrated. In the present case is the expansion cell 19 on the side wall 8th of the module housing 3 arranged and not on the top wall 9 of the module housing 3 adjacent. At the expansion cell 19 Thus, in the present case, gravity is not used to reduce the volume of the receiving space 11 used, which through the Dehnzelle 19 is provided. The walls 22 the expansion cell 19 namely have the desire to take their lower initial volume again, if due to the cooling of the thermal oil 5 this again from the recording room 11 in the module housing 3 flows.

Also the expansion cell 19 is present in a chamber 24 taken, which on the module housing 3 is arranged. So it remains independent of the volume, which is the thermal oil 5 takes that from the chambers 15 . 24 and the module housing 3 occupied volume constant.

An insulating material 25 , which is the module housing 3 and the chambers 15 . 24 encloses, is only partially shown in the figure. In the high-temperature battery 1 encloses however the insulating material 25 both the module housing 3 as well as the to the module housing 4 adjoining chamber 15 . 24 ,

In the figure is a module housing 3 with two to the module housing 3 adjacent chambers 15 . 24 shown. However, in alternative embodiments, only one chamber may be used 15 . 24 be provided, in which, for example, the diaphragm bellows 10 or the expansion cell 19 can be located.

The battery 1 may also be a plurality of module housings 3 include, which with one or more of the receiving spaces 11 to be able to communicate. The insulating material 25 then preferably surrounds the majority of the module housing 3 as well as the at least one chamber 15 . 24 in which at least one expansion vessel or expansion body the at least one receiving space 11 provides.

Claims (12)

High temperature battery ( 1 ) with a battery module ( 2 ), which at least one module housing ( 3 ) and a plurality of in the at least one module housing ( 3 ) arranged battery cells ( 4 ), and with a tempering medium for dissipating heat from the battery cells ( 4 ), characterized in that the temperature control medium is used as the bath liquid ( 5 ), wherein the at least one module housing ( 3 ) at least one passage ( 12 . 20 . 21 ) for the bath liquid ( 5 ) over which a receiving space ( 11 ) for the bath liquid ( 5 ) and the at least one module housing ( 3 ) are fluidly coupled together. High-temperature battery according to claim 1, characterized in that the receiving space ( 11 ) to an environment of the module housing ( 3 ) is closed and has a variable volume. High-temperature battery according to claim 1 or 2, characterized in that the receiving space ( 11 ) by a diaphragm bellows ( 10 ). High-temperature battery according to claim 3, characterized in that the membrane bellows ( 10 ) on the module housing ( 3 ) is arranged such that gravity causes a movement of the receiving space ( 11 ) from a first state having a first volume to a second state having a second, lower volume. High-temperature battery according to one of claims 2 to 4, characterized in that the high-temperature battery ( 1 ) at least one spring element ( 17 ), by means of which reducing the volume of the receiving space ( 11 ) is feasible. High-temperature battery according to one of claims 1 to 5, characterized in that the receiving space ( 11 ) by a strain cell ( 19 ). High-temperature battery according to one of claims 1 to 6, characterized in that the receiving space ( 11 ) bounding walls ( 14 . 22 ) within a chamber ( 15 . 24 ) are arranged, which on the module housing ( 3 ) is arranged. High temperature battery according to claim 7, characterized in that the chamber ( 15 . 24 ) and the module housing ( 3 ) are surrounded by an insulating material. High-temperature battery according to claim 7 or 8, characterized in that a plurality of the chambers ( 15 . 24 ) and a plurality of module housings ( 3 ) are surrounded by an insulating material. High-temperature battery according to one of claims 1 to 9, characterized in that at least one wall ( 26 . 22 ) of the recording room ( 11 ) is flexible and / or formed of an elastic material. High-temperature battery according to one of claims 1 to 10, characterized in that at least one wall ( 14 . 26 . 22 ) of Recording room ( 11 ) is formed of a steel and / or an aluminum alloy. High-temperature battery according to Claim 2 or according to one of Claims 3 to 11, in the back reference to Claim 2, characterized in that, when the pressure of the heat transfer medium ( 5 ) of about 200 mbar the volume of the receiving space ( 11 ) has a maximum size.

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