DE102012018040A1 - Single cell i.e. lithium ion single cell, for high volt battery for e.g. electric car, has electrode stack wrapped on mandrel, and cell components surrounding electrode stack in sections and comprising phase transition material - Google Patents

Abstract

The cell (1) has a cell housing (2) and an electrochemical active electrode stack (3) arranged in the cell housing formed as cell components. The electrode stack is wrapped on a mandrel (4) and contacted with pole contacts. The cell components surround the electrode stack in sections, where the cell components comprises phase transition material (7). The phase transition material is arranged in the pole contacts, in or at the cell housing and/or in the mandrel. The phase transition material is arranged between cell housing walls. Independent claims are also included for the following: (1) an electrochemical battery (2) a method for operating a single cell.

Description

The invention relates to a single cell for an electrochemical battery according to the features of the preamble of claim 1. The invention further relates to an electrochemical battery according to the features of the preamble of claim 5. The invention further relates to a method for operating a single cell for an electrochemical battery according to the Features of the preamble of claim 6.

Conventional single cells, in particular lithium-ion cells, are very sensitive to excessively high temperatures. By a corresponding structural design and an adapted operating behavior, the individual cells are normally operated in the uncritical temperature range.

In the event of an external trauma or a defect in the single cell and a resulting cell short circuit, critical temperatures can occur in a single cell. This can then lead to the so-called thermal runaway of the affected individual cell, d. H. such an overheated single cell can open by internal pressure increase, which can lead to the formation of gas and smoke as well as a fire.

In such a thermal runaway of a single cell, the chemical cell constituents react exothermically with each other when the critical temperature is exceeded, without further ado, ie. H. with heat generation with heavy gas and smoke generation. This can lead to fire, since the individual cells contain combustible electrolyte liquids, for example organic solvents such as dimethyl carbonate.

Other adjacent individual cells in an electrochemical battery can be damaged or destroyed, so that may damage or destroy the entire electrochemical battery and / or the entire vehicle.

The DE 40 13 269 A1 describes a high temperature storage battery, which is limited by a thermal insulation, in the interior of electrically interconnected memory cells are arranged and supported. The memory cells are supported so that sufficient cooling and heating of the memory cells is possible. For this purpose, the memory cells are embedded to form a memory cell block in a potting compound or a coarse-grained bulk material. In this memory cell block cooling devices are integrated or arranged outside directly and heat conductively adjacent to this block. Heating elements for heating the memory cells are also provided.

The DE 10 358 582 A1 describes a battery with heat transfer means comprising at least one battery cell with a doll surrounded by a cell jacket. This doll is hollow in its interior and is flowed through by a heat conducting medium or filled with such a means. The doll and the cell jacket thereby represent means for heat dissipation from the inside of the battery.

The US Pat. No. 7,931,979 B2 describes a battery in whose housing a so-called phase change material is arranged.

It is an object of the present invention to provide a prior art single cell for an electrochemical battery, an improved electrochemical battery and an improved method of operating a single cell for an electrochemical battery.

The object is achieved by a single cell for an electrochemical battery having the features of claim 1.

With regard to the electrochemical battery, the object is achieved by the features specified in claim 6.

With regard to the method for operating a single cell for an electrochemical battery, the object is achieved by the features specified in claim 6.

Preferred embodiments and further developments of the invention are specified in the dependent claims.

The individual cell comprises as cell components at least one cell housing and an electrochemically active electrode stack arranged in the cell housing which is wound on a winding mandrel and contacted with pole contacts, wherein according to the invention at least one cell component at least partially surrounding the electrode stack and at least one cell component at least partially surrounded by the electrode stack have a phase change material.

By means of the phase change material, a temperature increase within the single cell, especially in the case of a cell short circuit, is slowed down and limited.

By arranging the phase transition material on or in a cell component surrounding the electrode stack at least in sections, and on or in a cell component at least partially surrounded by the electrode stack, the electrode stack is connected to the cell stack Phase transition material brought into operative connection both inside and outside. In this way, a particularly uniform heat distribution and heat absorption within the single cell and efficient heat removal from the single cell allows.

Particularly advantageously, such local overtemperature regions within the single cell, which can form a starting point of the described thermal runaway, are largely avoided.

Particularly advantageously, by means of the outside of the electrode stack, for example, on or in the cell housing, arranged phase transition material, a thermal energy of adjacent individual cells in an electrochemical battery can be accommodated.

This advantageously prevents an individual cell from exceeding a critical temperature due to an internal or external short circuit, at which point the described thermal runaway occurs.

Furthermore, a fire of the damaged individual cell and / or the electrochemical battery is avoided. In particular, a so-called domino effect in the cell assembly of the electrochemical battery, d. H. damage to surrounding single cells by a single defective single cell, avoided.

Thus, a security of a single cell according to the invention is significantly improved.

In one possible embodiment, the phase change material is arranged in at least one pole contact, in or on the cell housing and / or in the winding mandrel. In a preferred embodiment, the cell housing is double-walled, wherein the phase transition material is arranged between the cell housing walls. As a result, the phase change material is safely separated from the remaining chemically active materials of the single cell.

Advantageously, thermal energy can be absorbed by the phase transition material through a phase change. Thus, the free in case of damage to the single cell thermal energy, which usually causes the fire, safely absorbable.

Particularly advantageously, the phase change can be carried out at a predeterminable temperature. Thereby, the temperature rise within the single cell can be limited to a temperature which is below a destruction temperature of the individual components of the electrochemically active electrode stack.

Conveniently, a plurality of individual cells designed according to the invention are electrically connected in series and / or parallel to an electrochemical battery.

In the method for operating a single cell for an electrochemical battery, a phase change material is arranged according to the invention in at least one cell component, in particular in at least one pole contact, in or on a cell housing and / or in a mandrel, so that a temperature increase within the single cell slows down and on a specifiable temperature is limited. In this way, an uncontrolled release of thermal energy and / or a fire of the single cell are safely avoided.

As a predeterminable temperature, a temperature below a destruction temperature of the individual components of the electrochemically active electrode stack is preferably predetermined. As a result, a temperature increase within the single cell is limited to a non-critical temperature even in the event of a malfunction of the same and a so-called thermal runaway is certainly avoided.

The temperature increase within the single cell is limited by means of a phase change of the phase change material. In this phase change of the phase change material, the released thermal energy of the single cell is completely or almost completely absorbed and converted by the phase change material.

In particular, the phase change of the phase change material is effected by the thermal energy released in the event of a short circuit of the single cell.

Particularly advantageously, a recordable by means of the phase change of the phase transition material amount of thermal energy is formed corresponding to a storable within the single cell amount of electrical energy. As a result, the thermal energy exiting in the event of a malfunction of the individual cell is completely absorbed or absorbed by the phase transition material.

Embodiments of the invention are explained in more detail below with reference to drawings.

Showing:

1 1 is a schematic sectional view of a single cell in a first embodiment variant;

2 schematically a sectional view of a single cell in a second embodiment,

3 schematically a partial sectional view of a single cell in a first embodiment in a perspective view and

4 schematically a detailed representation of a pole contact.

Corresponding parts are provided in all figures with the same reference numerals.

1 schematically shows a sectional view of a single cell 1 in a first embodiment as a so-called prismatic single cell 1 ,

2 schematically shows a sectional view of a single cell 1 in a second embodiment as a round single cell 1 ,

The single cell 1 is preferably formed as a lithium-ion single cell and part of a conventional, not shown, electrochemical battery. The battery is, for example, a high-voltage battery for use as an energy store for electrical energy in a vehicle, not shown. The vehicle is in particular an electric vehicle or a hybrid vehicle, wherein at least one electric drive motor of the vehicle can be operated by means of the electrical energy stored in the battery. Alternatively or additionally, the battery, a so-called starter battery, can be used to start an internal combustion engine of the vehicle, wherein the vehicle can also have exclusively an internal combustion engine for driving.

The battery includes a plurality of electrically connected in series and / or parallel individual cells 1 , which are called prismatic (as in 1 shown) or round (as in 2 shown) single cells 1 can be trained. Each of the single cells 1 has as cell components at least one cell housing 2 and one in the cell case 2 arranged and surrounded by this electrochemically active electrode stack 3 on. The electrode stack 3 is formed in a manner not shown of stacked anode and cathode films, which are each separated by a Separatorfolie. The anode and cathode films and the separator film are conventionally on a winding mandrel 4 wound so that the electrode stack forms an electrode coil. Alternatively, the electrode stack 3 in unwrapped form within the cell housing 2 arranged.

3 schematically shows a partial sectional view of a single cell 1 in a first embodiment in a perspective view.

For electrical coupling, each of the individual cells comprises 1 at least two pole contacts 5 . 6 , where the single cells 1 an electrochemical battery by means not shown cell connectors are electrically coupled in parallel and / or in series with each other.

According to the invention, at least one of the electrode stack 3 at least partially surrounding cell component and at least one of the electrode stack 3 at least partially surrounded cell component in each case a phase change material 7 on.

This is the phase change material 7 in at least one of the pole contacts 5 . 6 , in or on the cell case 2 and / or in the winding mandrel 4 arranged.

By the arrangement of the phase change material 7 on or in one of the electrode stacks 3 at least partially surrounding cell component, such as the cell housing 2 , and on or in one of the electrode stacks 3 At least partially surrounded cell component, such as the pole contacts 5 . 6 or the winding mandrel 4 , is the electrode stack 3 with the phase change material 7 brought into operative connection both on the inside and on the outside. In this way, a particularly uniform heat distribution and heat absorption within the single cell 1 allows.

Furthermore, by means of the phase change material 7 a particularly uniform and efficient heat removal from the single cell 1 allows.

Particularly advantageously, such local over-temperature ranges are within the single cell 1 which can form a starting point of the so-called thermal runaway, safely avoided.

Particularly advantageously, by means of the outside on the electrode stack 3 , for example, on or in the cell housing 2 , arranged phase transition material 7 a thermal energy of adjacent single cells 1 can be received in an electrochemical battery.

Such a phase change material 7 In certain combinations of pressure and temperature changes its state of aggregation from solid to liquid and from liquid to gaseous and vice versa. In such a change of state of aggregation may be a phase change material 7 At constant temperature, a large amount of thermal energy, the so-called latent heat, give or absorb.

In other words, in a phase change material 7 the latent heat of absorption is much greater than the heat that it could absorb and store due to its normal specific heat capacity without the phase change effect.

Phase change materials 7 work by exploiting the enthalpy of reversible thermodynamic state changes. The most frequently used principle is the utilization of the phase transition from solid to liquid, ie solidification and melting.

In the area of the phase transition occurs despite receiving a large amount of thermal energy through the phase change material 7 no significant temperature change.

In this case, the phase change takes place at a predeterminable temperature, which in particular of a phase change material used 7 is dependent.

By means of the phase change material 7 is a temperature rise within the single cell 1 , especially with a cell short circuit, slows down and limits.

Particularly advantageously, the thermal energy released in the case of a cell short circuit of the single cell is completely or almost completely absorbed and converted by the phase transition material during a phase change.

In a first embodiment, the cell housing 2 formed double-walled, wherein between the cell housing walls, the phase change material 7 is arranged. This is the phase change material 7 certainly from the remaining chemically active materials of the single cell 1 , For example, the electrode stack 3 , separated.

In the in 2 illustrated embodiment is the phase change material 7 in the mandrel 4 brought in. In this case, the phase transition material is in the interior of the at least partially hollow winding mandrel 4 arranged and thus completely surrounded by the mandrel material.

In the in 1 illustrated embodiment is the phase change material 7 on the cell case 2 , For example, arranged on the outside.

4 schematically shows a detailed representation of a pole contact 5 . 6 , Such a pole contact 5 . 6 is at least partially hollow in the interior and with the phase transition material 7 filled.

In a particularly preferred embodiment, the phase change material 7 in several places in or on the single cell 1 arranged.

In operation of the single cell 1 is determined by the arrangement of the phase change material 7 in or at the single cell 1 a, in particular improper, temperature rise within the single cell 1 slowed down and limited to a predeterminable temperature. In this way, an uncontrolled release of thermal energy and / or a fire of the single cell are safely avoided.

Such an improper temperature rise, for example, results from an external violence or a defect of the single cell 1 and a cell short circuit caused thereby. It can be critical temperatures in a single cell 1 occur. This can then lead to the so-called thermal runaway of the affected individual cell 1 lead, ie such a overheated single cell 1 can be opened or blown up by internal pressure increase, which can lead to gas and smoke formation as well as a fire.

In such a thermal runaway of the single cell 1 the chemical cell constituents in particular of the electrode stack react 3 when the critical temperature is exceeded, the reaction is exothermic to one another without external intervention, ie, with generation of heat with gas and smoke generation. This can lead to fire as the single cells 1 combustible electrolyte liquids, for example, organic solvents such as dimethyl carbonate.

Furthermore, a so-called domino effect can occur in the cell assembly of the electrochemical battery, ie a damage of surrounding individual cells 1 through a single defective single cell 1 ,

Further adjacent single cells 1 In an electrochemical battery can be damaged or destroyed, so that may damage or destroy the entire electrochemical battery and / or the entire vehicle.

These effects are due to the uptake of the thermal energy of the single cell delivered in the event of a cell short circuit 1 through the phase change material 7 avoided.

As a predeterminable temperature is preferably a temperature below a destruction temperature of the individual components of the electrochemically active electrode stack 3 specified. This causes a temperature rise within the single cell 1 even with a malfunction of the same on An uncritical temperature is limited and a so-called thermal runaway is certainly avoided.

The temperature rise within the single cell 1 is by means of the phase change of the phase change material 7 limited. In this phase change of the phase change material 7 becomes the released thermal energy of the single cell 1 completely or almost completely of the phase change material 7 recorded and converted.

In this case, the phase change of the phase change material 7 from the case of a short circuit of the single cell 1 released thermal energy causes.

Particularly advantageously, one by means of the phase change of the phase change material 7 recordable amount of thermal energy corresponding to a storable within the single cell amount of electrical energy. Thus, in case of malfunction of the single cell 1 emerging thermal energy completely or almost completely absorbed or absorbed by the phase change material.

In particular, such a design of the single cell 1 and the total amount of phase change material disposed thereon and / or therein 7 such that the stored electrical energy of the single cell 1 the total thermal mass of the single cell 1 including the necessary enthalpy of fusion of the phase transition material used 7 starting from a normal temperature in the range of 20 to 35 ° Celsius can not over the predeterminable, also referred to as critical, heat temperature. As a critical temperature while a temperature is specified and designated, which for safe operation of the single cell 1 may not be exceeded. Above a critical temperature, destruction of the individual components of the electrode stack begins 3 , For example, the critical temperature of a separator film is 120 ° Celsius and the critical temperature of the anode and cathode films is 140 to 180 ° Celsius.

One for the single cell 1 predefinable critical temperature is below the critical temperatures of individual components of the electrode stack 3 lie.

Furthermore, the single cell 1 designed such that local over-temperature ranges within the single cell 1 are avoided.

Furthermore, the single cell 1 a predeterminable ratio between the storable amount of electrical energy, an external shape and the resulting surface area, the internal thermal conductivities and the thermal masses.

LIST OF REFERENCE NUMBERS

1

single cell

2

cell case

3

electrode stack

4

mandrel

5

first pole contact

6

second pole contact

7

Phase change material

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 4013269 A1 [0006]
• DE 10358582 A1 [0007]
• US 7931979 B2 [0008]

Claims (10)

Single cell ( 1 ) for an electrochemical battery, wherein the single cell ( 1 ) as cell components at least one cell housing ( 2 ) and one in the cell housing ( 2 ) arranged electrochemically active electrode stack ( 3 ), which on a mandrel ( 4 ) and with pole contacts ( 5 . 6 ), characterized in that at least one of the electrode stacks ( 3 ) at least partially surrounding cell component and at least one of the electrode stack ( 3 ) at least partially surrounded cell component in each case a phase change material ( 7 ) exhibit. Single cell ( 1 ) according to claim 1, characterized in that the phase change material ( 7 ) in at least one pole contact ( 5 . 6 ), in or on the cell housing ( 2 ) and / or in the mandrel ( 4 ) is arranged. Single cell ( 1 ) according to claim 1 or 2, characterized in that the cell housing ( 2 ) is formed double-walled, wherein between the cell housing walls, the phase change material ( 7 ) is arranged. Single cell ( 1 ) according to one of the preceding claims, characterized in that the phase-change material ( 7 ) thermal energy is absorbed by a phase change, wherein the phase change of the phase change material ( 7 ) is feasible at a predetermined temperature. Electrochemical battery formed from a plurality of electrically series and / or parallel coupled single cells ( 1 ) according to one of the preceding claims. Method for operating a single cell ( 1 ) for an electrochemical battery according to one of the preceding claims, characterized in that in at least one cell component, in particular in at least one pole contact ( 5 . 6 ), in or on a cell housing ( 2 ) and / or in a mandrel ( 4 ) a phase change material ( 7 ) is arranged so that a temperature rise within the single cell ( 1 ) and is limited to a predeterminable temperature. A method according to claim 6, characterized in that as a predeterminable temperature, a temperature below a destruction temperature of the individual components of the electrochemically active electrode stack ( 3 ) is given. A method according to claim 6 or 7, characterized in that the temperature rise within the single cell ( 1 ) by means of a phase change of the phase change material ( 7 ) is limited. Method according to claim 8, characterized in that the phase change of the phase change material ( 7 ) from the case of a short circuit of the single cell ( 1 ) released thermal energy is effected. A method according to claim 8 or 9, characterized in that one by means of the phase change of the phase change material ( 7 ) recordable amount of thermal energy corresponding to one within the single cell ( 1 ) storable amount of electrical energy is formed.

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