SE547267C2

SE547267C2 - Battery Module, Battery Pack, Vehicle, Temperature Control Arrangement, and Method of Controlling Temperature of Battery Cells

Info

Publication number: SE547267C2
Application number: SE2251487A
Authority: SE
Inventors: Christian Strietzel
Original assignee: Scania Cv Ab
Priority date: 2022-12-19
Filing date: 2022-12-19
Publication date: 2025-06-17
Also published as: WO2024136733A1; SE2251487A1; DE112023004278T5

Abstract

A battery module (1) is disclosed comprising a module casing (3), a plurality of battery cells (c1 - c11) arranged in the module casing (3), and at least one pad assembly (5) interposed between two adjacent battery cells (c1, c2). The pad assembly (5) comprises a first pad (p1) configured to shrink to obtain a reduced thickness (t1’) when the temperature (T) of the first pad (p1) is increased above a threshold temperature (Th). The threshold temperature (Th) is lower than an upper safety temperature limit (TL) of the plurality of battery cells (c1 - c11). The present disclosure further relates to a battery pack (10), a vehicle (20), a temperature control arrangement (21), a method (100) of controlling the temperature (T) of a plurality of battery cells (c1 - c11) of a battery module (1), a computer program, and a computerreadable medium (200).

Description

The present disclosure relates to battery module comprising a module casing and a plurality of battery cells arranged in the module casing. The present disclosure further relates to a battery pack comprising a number of battery modules, a vehicle comprising a battery pack, a temperature control arrangement for a battery module, a method of controlling the temperature of a plurality of battery cells of a battery module, a computer program, and a computer-readable medium.

BACKGROUND The use of electric drive for vehicles provides many advantages, especially regarding local emissions. Such vehicles comprise one or more electric propulsion motors configured to provide motive power to the vehicle. These types of vehicles can be divided into the categories pure electric vehicles and hybrid electric vehicles. Pure electric vehicles, sometimes referred to as battery electric vehicles, only-electric vehicles, and all-electric vehicles, comprise a pure electric powertrain and comprise no internal combustion engine and therefore produce no emissions in the place where they are used.

A hybrid electric vehicle comprises two or more distinct types of power, such as an internal combustion engine and an electric propulsion system. The combination of an internal combustion engine and an electric propulsion system provides advantages with regard to energy efficiency, partly because of the poor energy efficiency of an internal combustion engine at lower power output levels. Moreover, some hybrid electric vehicles are capable of operating in pure electric drive when wanted, such as when driving in certain areas.

In at least partially electric vehicles, such as pure electric vehicles and hybrid electric vehicles, the electricity is usually stored in a number of battery packs each comprising a number of rechargeable battery cells. Some different types of battery cells are used, such as lithium-ion battery cells, lithium polymer battery cells, as well as other types of rechargeable battery cells. A large number of battery cells is normally needed to ensure a sufficient available operational range of a vehicle, system voltage and power, especially in battery packs for heavier types of vehicles.

A common packing solution is to arrange battery cells in battery modules. The battery cells may be arranged side by side inside a module casing of the battery module thereby forming a row of battery cells inside the battery module. The battery cells are normally tightly packed into the battery modules. Moreover, a number of modules may be arranged side by side and in several layers in a battery pack.

Battery cells generate heat during charging and discharging. Partly as a reason thereof, at least partially electrical vehicles normally comprise a battery cooling system configured to control the temperature of the battery cells of the vehicle. Moreover, the efficiency of a battery cell is dependent on the temperature of the battery cell. Therefore, in some vehicles, the battery cooling system is used to heat the battery cells prior to use of the vehicle.

Battery cells are costly components and the lifetime thereof is a concern both regarding the cost-aspect and for environmental reasons. The temperature of a battery cell significantly affects the lifetime of the battery cell. That is, if the battery cell is subjected to too high temperatures, it may significantly reduce the lifetime of the battery cell. Moreover, battery cells may become damaged if subjected to too high temperatures.

In more detail, battery cells are normally associated with an upper safety temperature limit meaning that if the temperature of a battery cell is rising above the upper safety temperature limit, the battery cell may become damaged. Moreover, if the temperature of a battery cell is rising above the upper safety temperature limit, the temperature of the battery cell may increase in an uncontrolled manner. Such an uncontrolled increase in temperature may cause a thermal runaway which may cause safety issues.

For the above given reasons, the temperature of battery cells of an at least partially electric vehicle is preferably controlled to be within a predetermined temperature range during operation of the vehicle.

Another aspect that affects the lifetime of a battery cell is the external pressure exerted onto the battery cell. An external pressure may be exerted onto battery cells of a battery module by forces acting between adjacent battery cells in the battery module and forces between battery cells and walls of the module casing of the battery module. Some types of battery cells are particularly sensitive to variations in the external pressure exerted onto the battery cell, such as lithium-ion battery cells with a high nickel content. Lithium-ion battery cells with a high nickel content have the advantage of a high energy storing capacity. Moreover, lithium-ion battery cells with a high nickel content are normally less costly than lithium-ion battery cells with a high cobalt content, simply due to the fact that cobalt is normally more costly than nickel. However, as indicated above, lithium-ion battery cells with a high nickel content are more sensitive to variations in the external pressure exerted onto the battery cell.

The external pressure exerted onto a battery cell may impact the lifetime of the battery cell throughout the lifetime of the battery cell. That is, if the external pressure exerted onto a battery cell is too low in the beginning of the lifetime of the battery cell, sheet wrinkling might occur which reduces lifetime of the battery cell considerably. In addition, an insufficient external pressure exerted onto a battery cell may cause bad contact between electrodes of the battery cell and inactive areas on the electrolyte of the battery cell.

However, if the external pressure exerted onto a battery cell becomes too high, the lifetime of the battery cell may significantly be reduced, for example due to cracking of a solid electrolyte interface SEI of the battery cell. Moreover, battery cells are subjected to some degree of swelling during the lifetime of the battery cell. That is, the battery cell may swell to occupy a larger volume after a certain time. Upon swelling, the battery cells inside a battery module may be subjected to considerable higher external pressures exerted onto the battery cells. As understood from the above, occurrences of too high external pressures exerted onto the battery cells are particularly likely to occur near an end of the lifetime of a battery cell, or at least after some operational time of the battery cells.

Furthermore, in most cases, battery modules and battery packs comprising battery modules are costly and complex to dissemble and repair and it may be difficult to adjust the external pressure exerted onto battery cells after assembly of a battery module or of a battery pack comprising a number of battery modules.

SUMMARY It is an object of the present invention to overcome, or at least alleviate, at least some of the above-mentioned problems and drawbacks.

According to a first aspect of the invention, the object is achieved by a battery module comprising a module casing, a plurality of battery cells arranged in the module casing, and at least one pad assembly interposed between two adjacent battery cells of the plurality of battery cells. The pad assembly comprises a first pad configured to shrink to obtain a reduced thickness when the temperature of the first pad is increased above a threshold temperature. The threshold temperature is lower than an upper safety temperature limit of the plurality of battery cells.

Thereby, a battery module is provided in which the external pressure exerted onto the plurality of battery cells can be reduced simply by increasing the temperature of the first pad to a temperature between the threshold temperature and the upper safety temperature limit. Since the threshold temperature is lower than the upper safety temperature limit of the plurality of battery cells, the temperature of the first pad can be increased to such a temperature by increasing the temperature of the battery module, including the battery cells thereof, in a safe manner without risking damage of the battery cells.

Accordingly, due to these features, the first pad can be shrunk to reduce the external pressure exerted onto the plurality of battery cells in a simple and efficient manner without having to dissemble the battery module and without having to mount any costly or complex arrangements or systems in the battery module for reducing external pressure exerted onto the plurality of battery cells.

As a further result, a battery module is provided having conditions for a prolonged lifetime of the plurality of battery cells. This is because swelling of the plurality of battery cells due to aging can be compensated for simply by causing the first pad to shrink to obtain the reduced thickness after a certain operational time of the battery module.

Moreover, conditions are provided for a prolonged lifetime of the plurality of battery cells because conditions are provided for obtaining an advantageous external pressure exerted onto the battery cells upon assembly of the battery module, while being able to reduce the external pressure after a certain operational time of the battery module, i.e., when some swelling of the plurality of battery cells can be expected to have occurred.

Accordingly, a battery module is provided overcoming, or at least alleviating, at least some of the above-mentioned problems and drawbacks. As a result, the above-mentioned object is achieved.

Optionally, the plurality of battery cells are lithium-ion battery cells with a high nickel content, such as a nickel content exceeding 80%.

Thereby, a battery module is provided having conditions for a high energy storing capacity and having conditions for being provided in a cost-efficient manner, while it can be ensured that the plurality of battery cells is not damaged due to an excessive external pressure exerted onto the plurality of battery cells caused by swelling of the plurality of battery cells. In other words, a battery module is provided having improved conditions for utilizing battery cells in the form of lithium-ion battery cells with a high nickel content without surpassing limits on external pressure exerted onto the battery cells.

Optionally, the battery cells of the plurality of battery cells are configured to operate within a predetermined temperature range being lower than the threshold temperature. Thereby, a battery module is provided having conditions for operating in an efficient manner while ensuring that the thickness of the first pad is only intentionally reduced to the reduced thickness, for example when wanting to lower the external pressure exerted onto the plurality of battery cells inside the battery module.

The threshold temperature is within the range of 50 - 90 degrees Celsius or is within the range of 60 - 85 degrees Celsius. Thereby, a battery module is provided having conditions for operating in an efficient manner while ensuring that the thickness of the first pad is only intentionally reduced to the reduced thickness, for example when wanting to lower the external pressure exerted onto the plurality of battery cells.

Optionally, the first pad is configured to obtain a reduced thickness of at least 30%, or at least 50%, when the temperature of the first pad is increased above the threshold temperature. Thereby, the external pressure exerted onto the plurality of battery cells can be significantly reduced in an efficient manner simply by increasing the temperature of the plurality of battery cells above the threshold temperature.

Optionally, the first pad is configured such that the thickness thereof changes by less than 15% when the temperature of the first pad declines from a temperature between the upper safety temperature limit and the threshold temperature to a temperature below the threshold temperature. Thereby, it is ensured that a reduction in the external pressure exerted onto the plurality of battery cells is substantially maintained after having increased the temperature of the plurality of battery cells above the threshold temperature. As a further result thereof, further improved conditions are provided for prolonging the lifetime of the plurality of battery cells.

Optionally, the pad assembly comprises a second pad, and wherein the first and second pads together are configured to apply a separating pressure between the two adjacent battery cells. Thereby, improved conditions are provided for obtaining an advantageous external pressure exerted onto the battery cells upon assembly of the battery module, while being able to reduce the external pressure after a certain operational time of the battery module, i.e., when some swelling of the plurality of battery cells can be expected to have occurred. In other words, it can be ensured the external pressure exerted onto the plurality of battery cells is kept within a preferred pressure range before the first pad is shrunk to obtain the reduced thickness as well as after the first pad is shrunk to obtain the reduced thickness. Accordingly, due to these features, further improved conditions are provided for prolonging the lifetime of the plurality of battery cells.

Optionally, the second pad is formed by an elastic material. Thereby, further improved conditions are provided for obtaining an advantageous external pressure exerted onto the battery cells upon assembly of the battery module, while being able to reduce the external pressure after a certain operational time of the battery module, i.e., when some swelling of the plurality of battery cells can be expected to have occurred. In other words, it can be further ensured the external pressure exerted onto the plurality of battery cells is kept within a preferred pressure range before the first pad is shrunk to obtain the reduced thickness as well as after the first pad is shrunk to obtain the reduced thickness. This is because the elastic material of the second pad can ensure a certain pressure between the two adjacent battery cells before the first pad is shrunk to obtain the reduced thickness as well as after the first pad is shrunk to obtain the reduced thickness. Accordingly, due to these features, further improved conditions are provided for prolonging the lifetime of the plurality of battery cells.

Optionally, the second pad is arranged to expand to obtain an increased thickness upon a reduction in thickness of the first pad. Thereby, it can be further ensured the external pressure exerted onto the plurality of battery cells is kept within a preferred pressure range before the first pad is shrunk to obtain the reduced thickness as well as after the first pad is shrunk to obtain the reduced thickness. This is because the expansion of the second pad can ensure that a certain pressure is applied between the two adjacent battery cells also after the first pad has obtained the reduced thickness. Accordingly, due to these features, further improved conditions are provided for prolonging the lifetime of the plurality of battery cells.

Optionally, the second pad is compressed between the first pad and one of the two adjacent battery cells to obtain a reduced thickness upon assembly of the battery module. Thereby, conditions are provided for obtaining an advantageous external pressure exerted onto the battery cells upon assembly of the battery module, while being able to reduce the external pressure after a certain operational time of the battery module, i.e., when some swelling of the plurality of battery cells can be expected to have occurred. In other words, it can be further ensured the external pressure exerted onto the plurality of battery cells is kept within a preferred pressure range before the first pad is shrunk to obtain the reduced thickness as well as after the first pad is shrunk to obtain the reduced thickness. Accordingly, due to these features, further improved conditions are provided for prolonging the lifetime of the plurality of battery cells.

Optionally, the first pad is formed by a material being stiffer than the material of the second pad at temperatures below the threshold temperature. Thereby, a further improved control can be provided of the pressure exerted onto the battery cells of the battery module. This is because the second pad can absorb changes in width of the battery cells so as to maintain pressure exerted onto the battery cells within a preferred pressure range whereas the first pad can be used to reduce the external pressure after a certain operational time of the battery module, i.e., when some swelling of the plurality of battery cells can be expected to have occurred.

Optionally, the battery cells of the plurality of battery cells are prismatic battery cells.

Thereby, a battery module is provided having conditions for a high energy storage capacity while being able to reduce the external pressure acting on the plurality of battery cells after a certain operational time of the battery module.

According to a second aspect of the invention, the object is achieved by a battery pack comprising a number of battery modules according to according to some embodiments of the present disclosure.

Since the battery pack comprises a number of battery modules according to according to some embodiments, a battery pack is provided in which the external pressure exerted onto battery cells thereof can be reduced simply by increasing the temperature of the first pad to a temperature between the threshold temperature and the upper safety temperature limit. Since the threshold temperature is lower than the upper safety temperature limit of the plurality of battery cells, the temperature of the first pad can be increased to such a temperature by increasing the temperature of the battery pack, including the battery cells thereof, in a safe manner without risking damage of the battery cells.

Accordingly, due to these features, the first pad can be shrunk to reduce the external pressure exerted onto the plurality of battery cells in a simple and efficient manner without having to dissemble the battery pack and without having to mount any costly or complex arrangements or systems in the battery pack for reducing external pressure exerted onto the battery cells of the battery pack.

As a further result, a battery pack is provided having conditions for a prolonged lifetime of the battery cells of the battery pack. This is because swelling of the battery cells of the battery pack due to aging can be compensated for simply by causing the first pad to shrink to obtain the reduced thickness.

Moreover, conditions are provided for a prolonged lifetime of the battery cells of the battery pack because conditions are provided for obtaining an advantageous external pressure exerted onto the battery cells upon assembly of the battery pack, while being able to reduce the external pressure after a certain operational time of the battery pack, i.e., when some swelling of the plurality of battery cells can be expected to have occurred.

Accordingly, a battery pack is provided overcoming, or at least alleviating, at least some of the above-mentioned problems and drawbacks. As a result, the above-mentioned object is achieved.

According to a third aspect of the invention, the object is achieved by a vehicle comprising an electric propulsion machine configured to provide motive power to the vehicle and a battery pack according to some embodiments of the present disclosure, wherein the battery pack is configured to supply electricity to the electric propulsion machine. Since the vehicle comprises a battery pack according to some embodiments, a vehicle is provided overcoming, or at least alleviating, at least some of the above-mentioned problems and drawbacks. As a result, the above-mentioned object is achieved.

According to a fourth aspect of the invention, the object is achieved by a temperature control arrangement for a battery module, the battery module comprising a module casing, a plurality of battery cells arranged in the module casing, and at least one pad assembly interposed between two adjacent battery cells of the plurality of battery cells, wherein the pad assembly comprises a first pad configured to shrink to obtain a reduced thickness when the temperature of the first pad is increased above a threshold temperature, and wherein the threshold temperature is lower than an upper safety temperature limit of the plurality of battery cells. The temperature control arrangement is configured to: - control the temperature of the plurality of battery cells to be within a predetermined temperature range during a plurality of charging cycles of the plurality of battery cells, the predetermined temperature range being lower than the threshold temperature, and then - cause the first pad to obtain the reduced thickness by temporarily increasing the temperature of the plurality of battery cells to a temperature between the threshold temperature and the upper safety temperature limit of the plurality of battery cells.

Thereby, a temperature control arrangement is provided capable of reducing the external pressure exerted onto the plurality of battery cells in a simple and efficient manner without having to dissemble the battery module and without having to mount any costly or complex arrangements or systems in the battery module for reducing external pressure exerted onto the plurality of battery cells.

Since the threshold temperature is lower than the upper safety temperature limit of the plurality of battery cells, the temperature control arrangement can increase the temperature of the first pad to such a temperature in a safe manner by temporarily increasing the temperature of the plurality of battery cells to a temperature between the threshold temperature and the upper safety temperature limit, without risking damage of the battery cells.

As a further result, a temperature control arrangement is provided having conditions for prolonging the lifetime of the plurality of battery cells of the battery module. This is because the temperature control arrangement can compensate swelling of the plurality of battery cells due to aging simply by causing the first pad to obtain the reduced thickness.

Moreover, controlling the temperature of the plurality of battery cells to be within a predetermined temperature range during the number of charging cycles of the plurality of battery cells, the temperature control arrangement allows for an efficient operation of the plurality of battery cells, while ensuring a long lifetime of the plurality of battery cells.

Accordingly, a temperature control arrangement is provided overcoming, or at least alleviating, at least some of the above-mentioned problems and drawbacks. As a result, the above-mentioned object is achieved.

Optionally, the battery module comprises a thermal management system. According to such embodiments, the temperature control arrangement may be configured to control the temperature of the plurality of battery cells by controlling operation of the thermal management system.

According to a fifth aspect of the invention, the object is achieved by a method of controlling the temperature of a plurality of battery cells of a battery module, the battery module comprising a module casing, the plurality of battery cells arranged in the module casing, and at least one pad assembly interposed between two adjacent battery cells of the plurality of battery cells, wherein the pad assembly comprises a first pad configured to shrink to obtain a reduced thickness when the temperature of the first pad is increased above a threshold temperature, and wherein the threshold temperature is lower than an upper safety temperature limit of the plurality of battery cells, and wherein the method comprises the steps of: - controlling the temperature of the plurality of battery cells to be within a predetermined temperature range during a number of charging cycles of the plurality of battery cells, the predetermined temperature range being lower than the threshold temperature, and then - causing the first pad to obtain the reduced thickness by temporarily increasing the temperature of the plurality of battery cells to a temperature between the threshold temperature and the upper safety temperature limit of the plurality of battery cells.

Thereby, a method is provided capable of reducing the external pressure exerted onto the plurality of battery cells in a simple and efficient manner without having to dissemble the battery module and without having to mount any costly or complex arrangements or systems in the battery module for reducing external pressure exerted onto the plurality of battery cells.

Since the threshold temperature is lower than the upper safety temperature limit of the plurality of battery cells, the temperature of the first pad can be increased by temporarily increasing the temperature of the plurality of battery cells to a temperature between the threshold temperature and the upper safety temperature limit in a safe manner without risking damage of the battery cells.

As a further result, a method is provided having conditions for prolonging the lifetime of the plurality of battery cells of the battery module. This is because the method can compensate swelling of the plurality of battery cells due to aging simply by causing the first pad to obtain the reduced thickness.

Moreover, by controlling the temperature of the plurality of battery cells to be within a predetermined temperature range during the number of charging cycles of the plurality of battery cells, the method allows for an efficient operation of the plurality of battery cells, while ensuring a long lifetime of the plurality of battery cells.

Accordingly, a method is provided overcoming, or at least alleviating, at least some of the above-mentioned problems and drawbacks. As a result, the above-mentioned object is achieved.

Optionally, the battery module comprises a thermal management system. According to such embodiments, the step of controlling the temperature of the plurality of battery cells and the step of causing the first pad to obtain the reduced thickness may be performed by controlling operation of the thermal management system.

Optionally, the method comprises the step of, after the step of causing the first pad to obtain the reduced thickness: - controlling the temperature of the plurality of battery cells to be within the predetermined temperature range during a number of following charging cycles of the plurality of battery cells.

The method allows for an efficient operation of the plurality of battery cells during the number of following charging cycles, while ensuring a long lifetime of the plurality of battery cells.

Optionally, the battery module comprises a thermal management system. According to such embodiments, the step of controlling the temperature of the plurality of battery cells may be performed by controlling the thermal management system.

It will be appreciated that the various embodiments described for the method are all combinable with the temperature control arrangement as described herein. That is, the temperature control arrangement according to the fourth aspect of the invention may be configured to perform any one of the method steps of the method according to the fifth aspect of the invention.

According to a sixth aspect of the invention, the object is achieved by a computer program comprising instructions which, when the program is executed by a computer, cause the computer to carry out the method according to some embodiments of the present disclosure. Since the computer program comprises instructions which, when the program is executed by a computer, cause the computer to carry out the method according to some embodiments, a computer program is provided which provides conditions for overcoming, or at least alleviating, at least some of the above-mentioned drawbacks. As a result, the abovementioned object is achieved.

According to a seventh aspect of the invention, the object is achieved by a computerreadable medium comprising instructions which, when executed by a computer, cause the computer to carry out the method according to some embodiments of the present disclosure. Since the computer-readable medium comprises instructions which, when the program is executed by a computer, cause the computer to carry out the method according to some embodiments, a computer-readable medium is provided which provides conditions for overcoming, or at least alleviating, at least some of the above-mentioned drawbacks. As a result, the above-mentioned object is achieved.

Further features of, and advantages with, the present invention will become apparent when studying the appended claims and the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS Various aspects of the invention, including its particular features and advantages, will be readily understood from the example embodiments discussed in the following detailed description and the accompanying drawings, in which: Fig. 1 schematically illustrates a vehicle according to some embodiments of the present disclosure, Fig. 2 schematically illustrates a battery pack of the vehicle illustrated in Fig. 1, Fig. 3 schematically illustrates a perspective view of a first casing layer of a battery pack according to the embodiments illustrated in Fig. 1 and Fig. 2, Fig. 4a schematically illustrates a cross section through a portion of a battery module of a first casing layer of the battery pack illustrated in Fig. 3, Fig. 4b illustrates the cross section through the portion of the battery module illustrated in Fig. 4a in which two adjacent battery cells have been subjected to some swelling, Fig. 4c illustrates the cross section through the portion of the battery module illustrated in Fig. 4a and Fig. 4b in which a first pad has been shrunk to obtain a reduced thickness, Fig. 5 illustrates a method of controlling the temperature of a plurality of battery cells of a battery module, Fig. 6 illustrates two graphs comprising a lower graph indicating a state of charge level of a plurality of battery cells during a number of charging cycles and an upper graph indicating the temperature of the plurality of battery cells during the number of charging cycles, Fig. 7 illustrates a graph showing a correlation between a separating pressure between two adjacent battery cells and a compression ratio of a second pad according to embodiments herein, and Fig. 8 illustrates a computer-readable medium.

Aspects of the present invention will now be described more fully. Like numbers refer to like elements throughout. Well-known functions or constructions will not necessarily be described in detail for brevity and/or clarity.

Fig. 1 schematically illustrates a vehicle 20, according to some embodiments of the present disclosure. According to the illustrated embodiments, the vehicle 20 is a truck, i.e., a type of heavy vehicle. According to further embodiments, the vehicle 20, as referred to herein, may be another type of heavy or lighter type of manned or unmanned vehicle for land or waterbased propulsion such as a lorry, a bus, a construction vehicle, a tractor, a car, a ship, a boat, or the like.

The vehicle 20 comprises an electric powertrain 42. According to the illustrated embodiments, the electric powertrain 42 is configured to provide motive power to the vehicle 20 via wheels 57 of the vehicle 20. The electric powertrain 42 comprises an electric propulsion machine 33. The electric propulsion machine 33 is capable of providing motive power to the vehicle 20 via wheels 57 of the vehicle 20 as well as providing regenerative braking of the vehicle 20. Thus, according to the illustrated embodiments, the electric propulsion machine 33 is capable of operating as an electric motor as well as an electric generator. The electric propulsion machine 33 of the vehicle 20 may also be referred to as a vehicle propulsion motor/generator.

According to the illustrated embodiments, the electric powertrain 42 of the vehicle 20 is a pure electric powertrain 42, i.e., a powertrain comprising no internal combustion engine. According to further embodiments, the electric powertrain 42 of the vehicle 20 may be a socalled hybrid electric powertrain 42 comprising a combustion engine in addition to the electric propulsion machine 33 for providing motive power to the vehicle 20.

Moreover, as is indicated in Fig. 1, the vehicle 20 comprises a battery pack 10 and an electric system 40. The battery pack 10 is operably connected to the electric propulsion machine 33 via the electric system 40. In other words, the battery pack 10 is configured to provide electricity to the electric propulsion machine 33 via the electric system 40. Moreover, according to the illustrated embodiments, the battery pack 10 is configured to receive electricity from the electric propulsion machine 33 via the electric system 40 during regenerative braking of the vehicle 20. As is further explained herein, the battery pack 10 comprises a number of battery modules each comprising a number of battery cells. In Fig. 1, the vehicle 20 is illustrated as comprising one battery pack 10. However, the vehicle 20 may comprise more than one battery pack 10.

In Fig. 1, the vehicle 20 is illustrated as positioned onto a flat horizontal surface H in an intended use position. Moreover, in Fig. 1, a vertical direction vd of the vehicle 20 is indicated. The vertical direction vd of the vehicle 20 is perpendicular to the flat horizontal surface H when the vehicle 20 is positioned thereon in the intended use position. Moreover, the vertical direction vd of the vehicle 20 coincides with a local gravity vector at the location of the vehicle 20 when the vehicle 20 positioned onto a flat horizontal surface H in an intended use position. In Fig. 1, a horizontal direction hd of the vehicle 20 is indicated. The horizontal direction hd of the vehicle 20 is parallel to the flat horizontal surface H when the vehicle 20 is positioned thereon in the intended use position.

As can be seen in Fig. 1, the wheels 57 of the vehicle 20 are abutting the flat horizontal surface Hs when the vehicle 20 is positioned in the intended upright use position on the flat horizontal surface Hs. The vehicle 20 has a longitudinal direction Id. The longitudinal direction Id of the vehicle 20 is parallel to the flat horizontal surface Hs when the vehicle 20 is positioned in the intended upright use position thereon. Moreover, the longitudinal direction Id of the vehicle 20 is parallel to a forward moving direction fd of the vehicle 20 as well as to a reverse moving direction rd of the vehicle 20. The reverse moving direction rd of the vehicle 20 is opposite to the forward moving direction fd of the vehicle 20.

Fig. 2 schematically illustrates the battery pack 10 of the vehicle 20 illustrated in Fig. 1. The battery pack 10 comprises a casing 7 and a number of layers L1, L2, L3, L4 of battery cells arranged inside the casing 7. The reference sign for the layers L1, L2, L3, L4 of battery cells is abbreviated "L1 - L4" in some places herein for reasons of brevity and clarity. According to the embodiments illustrated in Fig. 2, the battery pack 10 comprises four layers L1 - L4 of battery cells arranged inside the casing 7. As is further explained herein, the battery pack 10 may comprise another number of layers L1 - L4 of battery cells arranged inside the casing 7, such as a number between one and twelve, or a number between one and eight.

The casing 7 forms a protective outer shell for battery modules inside the casing 7. That is, as is further explained herein, according to the illustrated embodiments, each layer L1 - L4 of battery cells comprises a number of battery modules, wherein each battery module comprises a number of battery cells arranged in a row. Thus, according to the illustrated embodiments, the casing 7 is configured to support these battery modules.

According to the illustrated embodiments, the casing 7 is formed by a number of casing sections 7.1, 7.2, 7.3, 7.4. The reference sign for the casing sections 7.1, 7.2, 7.3, 7.4 of the casing 7 is abbreviated "7.1 - 7.4" in some places herein for reasons of brevity and clarity.

According to the illustrated embodiments, each casing section 7.1 - 7.4 is configured to accommodate one layer L1 - L4 of battery cells. In other words, the battery pack 10 comprises the same number of casing sections 7.1 - 7.4 as the number of layers L1 - L4 of battery cells of the battery pack 10. According to the illustrated embodiments, two adjacent casing sections 7.1 - 7.4 of the number of casing sections 7.1 - 7.4 are attached to each other via a number of fastening elements.

Fig. 3 schematically illustrates a perspective view of a first casing layer 7.1 of the battery pack 10 according to the embodiments illustrated in Fig. 1 and Fig. 2. Moreover, in Fig. 3, the first layer L1 of battery cells c1 - c11 can be seen. Below, simultaneous reference is made to Fig. 1 - Fig. 3, if not indicated otherwise.

In Fig. 2 and Fig. 3, the longitudinal direction Id, the horizontal direction hd, the vertical direction vd, and a lateral direction Ia of the vehicle 20 illustrated in Fig. 1 are indicated. The lateral direction Ia is perpendicular to the vertical direction vd and is perpendicular to the longitudinal direction Id. In Fig. 2 and Fig. 3, the first casing layer 7.1 is illustrated in an intended mounting orientation relative to these directions vd, Id, hd, Ia.

According to the illustrated embodiments, the first layer L1 of battery cells c1 - c11 comprises a number of battery modules 1, 1' arranged adjacent to each other along the horizontal direction hd. In more detail, according to the illustrated embodiments, the battery modules 1, 1’ are arranged adjacent to each other along the longitudinal direction Id of the vehicle 20 illustrated in Fig. 1.

According to the embodiments illustrated in Fig. 3, the first layer L1 of battery cells c 11 - c11 comprises five battery modules 1, 1' arranged adjacent to each other along the longitudinal direction Id. According to further embodiments, the first layer L1 of battery cells c1 - c11 may comprise another number of battery modules 1, 1' such as a number between one and twelve, or a number between one and eight. Moreover, these battery modules 1, 1' may be oriented in another manner relative to the longitudinal direction Id of the vehicle 20.

Each battery module 1, 1' comprises one row r1 - r5 of battery cells c1 - c11 arranged in a respective module casing 3. In Fig. 3, only the module casing 3 and the battery cells c1 - c11 of one battery module 1 of the number of battery modules 1, 1' are indicated for reasons of brevity and clarity. However, according to the illustrated embodiments, each battery module 1, 1' comprise a plurality of battery cells c1 - c11 arranged in a module casing 3. The battery cells c1 - c11 may be lithium-ion battery cells, lithium polymer battery cells, or other types of rechargeable battery cells. According to the illustrated embodiments, the battery cells c1 -c11 are prismatic battery cells.

Moreover, according to the illustrated embodiments, each battery module 1, 1’ comprises a row r1 - r5 of eleven battery cells c1 - c11. According to further embodiments, each battery module 1, 1’ may comprise another number of battery cells c1 - c11, such as a number between two and twenty, or a number between six and twelve. According to the illustrated embodiments, the battery cells c1 - c11 of a row r1 - r5 of battery cells c1 - c11 are arranged adjacent to each other along the lateral direction Ia of the vehicle 20. However, the battery cells c1 - c11 of a row r1 - r5 of battery cells c1 - c11 may be arranged in another manner relative to the lateral direction Ia of the vehicle 20.

According to the embodiments of the battery pack 10 illustrated in Fig. 1 - Fig. 3, each layer L1 - L4 of the battery pack 10 comprises the same number of battery cells c1 - c11, battery modules 1, 1’, and rows r1 - r5 of battery cells c1 - c11 as the first layer L1 of battery cells c1 - c11 depicted in Fig. 3. Thus, in summary, according to the illustrated embodiments, each layer L1 - L4 of battery cells c1 - c11 comprises a number of battery modules 1, 1' arranged adjacent to each other, and wherein each battery module 1, 1' comprises one row r1 - r5 of battery cells c1 - c11.

According to further embodiments, the battery cells c1 - c11, the rows r1 - r5 of battery cells c1 - c11, and/or the layers L1 - L4 of battery cells c1 - c11 of a battery pack 10 as described herein may be arranged in another manner than described above and may be oriented in another manner relative to the longitudinal direction Id, the forward moving direction fd, the horizontal direction hd, the vertical direction vd, and the lateral direction Ia than described above.

The wording layer L1 - L4 of battery cells c1 - c11, as referred to herein, means that the battery cells c1 - c11 are arranged in such a manner in each layer L1 - L4 such that a line passing through the layer L1 - L4 crosses only one battery cell 5 when the line is parallel to one extension direction of the layer L1 - L4, namely the vertical direction vd according to the illustrated embodiments, and such that the line crosses several battery cells c1 - c11 when the line is parallel to another extension direction of the layer L1 - L4, namely one of the horizontal direction hd and the lateral direction Ia according to the illustrated embodiments.

As can be seen in Fig. 3, the battery module 1 comprises a number of pad assemblies 5, 5’, wherein each pad assembly 5, 5’ is arranged between two adjacent battery cells c1 - c11 . According to the illustrated embodiments, the battery module 1 comprises one pad assembly 5, 5’ between each pair of adjacent battery cells c1 - c1. In other words, according to the illustrated embodiments, the battery module 1 comprises ten pad assemblies 5, 5’. However, according to further embodiments, the battery module 1 may comprise another number of pad assemblies 5, 5’. Moreover, the pad assemblies 5, 5’ may not be interposed between each pair of adjacent battery cells c1 - c11 of the battery module 1.

In Fig. 3, only the pad assemblies 5, 5’ of one battery module 1 of the number of battery modules 1, 1’ are indicated for reasons of brevity and clarity. However, the remaining battery modules 1’ may comprise pad assemblies 5, 5’ according to the above described. The features, functions, and advantages of the pad assemblies 5, 5’ are described in more detail below.

Fig. 4a schematically illustrates a cross section through a portion of one of the battery modules 1 of the first casing layer L1 of the battery pack 10 illustrated in Fig. 3. In Fig. 4a, a first and a second battery cell c1, c2 can be seen. The first and second battery cells c1, c2 constitute two adjacent battery cells c1, c2 of the plurality of battery cells c1 - c11. The wording adjacent battery cells c1, c2, as used herein, means two neighbouring battery cells, i.e., two immediately adjacent battery cells.

In Fig. 4a, the cross section is made in a plane parallel to the longitudinal direction Id as well as the vertical direction vd indicated in Fig. 3. The components of Fig. 4a are not drawn to scale.

In Fig. 4a, one pad assembly 5 can be seen. The pad assembly 5 is interposed between the two adjacent battery cells d, c2. According to the embodiments illustrated in Fig. 4a, the pad assembly 5 comprises a first pad p1 and a second pad p2. As is further explained herein, the first and second pads p1, p2 are together configured to apply a separating pressure between the two adjacent battery cells c1 , c2.

Fig. 4b illustrates the cross section through the portion of the battery module illustrated in Fig. 4a in which the two adjacent battery cells c1, c2 have been subjected to some swelling. As can be seen in Fig. 4b, each of the two adjacent battery cells c1, c2 has obtained an increased width w1', w2’ as compared to the width w1, w2 of the battery cell c1, c2 in Fig. 4a. The increased width w1’, w2’ may be a result of swelling due aging of the battery cells c1, c2.

According to the illustrated embodiments, the second pad p2 is formed by an elastic material. The second pad p2 may for example be formed by polypropylene, expanded polypropylene, urethane, expanded urethane, or the like. Moreover, according to the illustrated embodiments, the first pad p1 is formed by a material being stiffer than the material of the second pad p2 at room temperatures, i.e., temperatures around 20 degrees Celsius. The first pad p1 may be formed by a material being at least 50% stiffer than the material of the second pad p2 at room temperatures, i.e., at temperatures around 20 degrees Celsius. The details of the material of the first pad p1 is further explained below.

According to the illustrated embodiments, the second pad p2 is configured to be compressed upon swelling to the battery cells c1, c2. As can be seen in Fig. 4b, the second pad p2 has obtained a reduced thickness t2’ as compared to thickness t2 of the second pad p2 in Fig. 4a. Moreover, as can be seen when comparing Fig. 4a and Fig. 4b, the thickness t1 of the first pad p1 is substantially maintained after the swelling to the battery cells c1, c2.

Fig. 4c illustrates the cross section through the portion of the battery module illustrated in Fig. 4a and Fig. 4b in which the first pad p1 has been shrunk to obtain a reduced thickness t1' low, simultaneous reference is made to Fig. 1 - Fig. 4c, if not indicated otherwise.

According to embodiments herein, the first pad p1 is configured to shrink to obtain a reduced thickness t1' when the temperature of the first pad p1 is increased above a threshold temperature. The threshold temperature may for example be within the range of 50 - 90 degrees Celsius or may be within the range of 60 - 85 degrees Celsius. The threshold temperature is lower than an upper safety temperature limit of the plurality of battery cells c1 - c11. The upper safety temperature limit of the plurality of battery cells c1 - c11 may for example be within the range of 92 - 150 degrees or may be within the range of 95 degrees -110 degrees. The upper safety temperature limit is an upper temperature limit for the plurality of battery cells c1 - c11 and sets an upper limit on the temperature the plurality of battery cells c1 - c11 at which the plurality of battery cells c1 - c11 is not risking becoming damaged.

As seen in Fig. 4c, according to the illustrated embodiments, the second pad p2 is arranged to expand to obtain an increased thickness t2" upon a reduction in thickness t1' of the first pad p1 In this manner, a separating pressure can be obtained between the battery cells d, c2 also after the first pad p1 has obtained the reduced thickness t1’, as is further explained herein.

In Fig. 1, a temperature control arrangement 21 is indicated. The temperature control arrangement 21 may be comprised in the vehicle 20 comprising the battery modules 1, 1', in a battery pack 10 comprising the battery modules 1, 1', and/or in one or more battery modules 1, 1' according to embodiments herein.

Moreover, the vehicle 20 illustrated in Fig. 1 comprises a thermal management system 24. The thermal management system 24 may also be referred to as a battery thermal management system 24. According to the illustrated embodiments, the temperature control arrangement 21 is operably connected to the thermal management system 24 and is configured to control the temperature of the battery cells c1 - c11 of the battery modules 1, 1' by controlling the operation of the thermal management system 24.

The thermal management system 24 may comprise a coolant circuit, one or more radiators, one or more cooling fans, one or more thermostatic valves, one or more coolant heating assemblies, and one or more coolant pumps configured to pump coolant through the coolant circuit. As indicated, according to the illustrated embodiments, the temperature control arrangement 21 is configured to control operation of the thermal management system 24. The temperature control arrangement 21 may for example be configured to control operation of the thermal management system 24 by controlling operation of the one or more cooling fans, the one or more thermostatic valves, the one or more coolant heating assemblies, and/or the one or more coolant pumps of the thermal management system 24.

Fig. 5 illustrates a method 100 of controlling the temperature of a plurality of battery cells of a battery module. The battery module may be a battery module 1, 1' as explained with reference to Fig. 1 - Fig. 4c above. The method 100, as referred to herein, may also be referred to as a method 100 of reducing a separating pressure between a plurality of battery cells c1 - c11 of a battery module 1, 1'.

Fig. 6 illustrates two graphs comprising a lower graph indicating a state of charge level SOC of a plurality of battery cells during a number of charging cycles Y1 - Yn+k and an upper graph indicating the temperature T of the plurality of battery cells during the number of charging cycles Y1 - Yn+k. Moreover, the method steps 110, 120, 130 of the method 100 illustrated in Fig. 5 are also indicated in Fig. 6.

The plurality of battery cells may be a plurality of battery cells c1 - c11 of a battery module 1, 1' according to the embodiments explained with reference to Fig. 1 - Fig. 5. Moreover, the temperature control arrangement 21 illustrated in Fig. 1 may be configured to perform any one of the steps 110, 120, 130 of the method 100 illustrated in Fig. 5 and Fig. 6. Therefore, below, simultaneous reference is made to Fig. 1 - Fig. 6, if not indicated otherwise.

The method 100 illustrated in Fig. 5 is a method 100 of controlling the temperature T of a plurality of battery cells c1 - c11 of a battery module 1, wherein the battery module 1 comprises a module casing 3, the plurality of battery cells c1 - c11 arranged in the module casing 3, and at least one pad assembly 5 interposed between two adjacent battery cells d, c2 of the plurality of battery cells c1 - c11. The pad assembly 5 comprises a first pad p1 configured to shrink to obtain a reduced thickness t1’ when the temperature T of the first pad p1 is increased above a threshold temperature Th. The threshold temperature Th is lower than an upper safety temperature limit TL of the plurality of battery cells c1 - c11.

As indicated in Fig. 5 and Fig. 6, the method 100 comprises the steps of: controlling 110 the temperature T of the plurality of battery cells c1 - c11 to be within a predetermined temperature range Tr during a number of charging cycles Y1 - Yn of the plurality of battery cells c1 - c11.

As seen in Fig. 6, the predetermined temperature range Tr is lower than the threshold temperature Th. The number of charging cycles Y1 - Yn of the plurality of battery cells c1 -c11 may be a high number, such as for example a couple of hundreds of charging cycles Y1 - Yn or more.

Moreover, as indicated in Fig. 5 and Fig. 6, the method 100 comprises the steps of: causing 120 the first pad p1 to obtain the reduced thickness t1’ by temporarily increasing the temperature T of the plurality of battery cells c1 - c11 to a temperature T between the threshold temperature Th and the upper safety temperature limit TL of the plurality of battery cells c1 - c11.

As can be seen in Fig. 6, the step of causing 120 the first pad p1 to obtain the reduced thickness t1’ is performed after the step of controlling 110 the temperature T of the plurality of battery cells c1 - c11 to be within a predetermined temperature range Tr during the number of charging cycles Y1 - Yn, i.e., after the cycle Yn indicated in Fig. 6. In more detail, according to the embodiments illustrated in Fig. 6, the step of causing 120 the first pad p1 to obtain the reduced thickness t1' can be said to be performed during a charging cycle Yn+1 even though the reference sign "Yn+1" is not indicated in Fig. 6 for reasons of brevity and clarity.

The step of causing 120 the first pad p1 to obtain the reduced thickness t1’ may be performed by controlling the thermal management system 24 of the vehicle 20 to temporarily increase the temperature T of the plurality of battery cells c1 - c11 to a temperature T between the threshold temperature Th and the upper safety temperature limit TL of the plurality of battery cells c1 - c11. As indicated in Fig. 6, the temperature T of the plurality of battery cells c1 - c11 may be temporarily increased to a temperature T just above the threshold temperature Th. The wording "temporarily increasing the temperature T", as used herein, means a timewise short increase of the temperature T of the plurality of battery cells c1 - c11 to a temperature T above the threshold temperature Th. As an example, the temperature T of the plurality of battery cells c1 - c11 may be controlled to be above the threshold temperature Th during a time period of a couple of minutes, such as 2 - 15 minutes.

Moreover, as indicated in Fig. 5 and Fig. 6, according to the illustrated embodiments, the method 100 comprises the steps of, after the step of causing 120 the first pad p1 to obtain the reduced thickness t1': controlling 130 the temperature T of the plurality of battery cells c1 - c11 to be within the predetermined temperature range Tr during a number of following charging cycles Yn+2 - Yn+k of the plurality of battery cells c1 - c11.

Accordingly, the step 130 is performed after the step 120. The charging cycle Yn+k may represent the last charging cycle of the plurality of battery cells c1 - c11. The number k in the expression Yn+k may thus be a high number such as a number of several hundreds or more.

As understood from the above, the battery cells c1 - c11 of the plurality of battery cells c1 -c11 are configured to operate within a predetermined temperature range Tr, wherein the predetermined temperature range Tr is lower than the threshold temperature Th.

Fig. 7 illustrates a graph showing the correlation between a separating pressure P between the two adjacent battery cells and a compression ratio Cr of a second pad according to embodiments herein. The two adjacent battery cells may be two adjacent battery cell c1, c2 according to the embodiments illustrated in Fig. 4a - Fig. 4c, and the compression ratio Cr may be indicative of a compression ratio Cr of a second pad p2 as explained with reference to Fig. 4a - Fig. 4c. Therefore, below, simultaneous reference is made to Fig. 1 - Fig. 7, if not indicated otherwise.

In Fig. 7, three different pressure regions r0, r1, r2 are indicated, namely a low-pressure region r0, an intermediate pressure region r1, and a high-pressure region r2.

The low-pressure region r0 is to be avoided because a low pressure P between the two adjacent battery cells c1, c2 may cause low external pressures applied onto the battery cells c1, c2 which can reduce the lifetime of the battery cells c1, c2, for example due to sheet wrinkling of the battery cells c1, c2. In addition, an insufficient external pressure exerted onto the battery cells c1, c2 may cause bad contact between electrodes of the battery cells c1, c2 and inactive areas on the electrolyte of the battery cells c1, c2.

Moreover, the high-pressure region r2 is to be avoided because if the external pressure exerted onto the battery cells c1, c2 becomes too high, the lifetime of the battery cells c1, c2 may significantly decrease, for example due to cracking of a solid electrolyte interface SEI of the battery cells c1, c2.

In Fig. 7, a first boundary b1 by between the low-pressure region r0 and the intermediate pressure region r1 is indicated. According to the illustrated embodiments, the separating pressure P1 at the first boundary b1 is approximately 150 kPa and the compression ratio Cr of the second pad p2 is approximately 43%. According to further embodiments, the separating pressure P1 at the first boundary b1 may be within the range of 30 kPa - 450 kPa, or may be within the range of 70 kPa - 250 kPa. Moreover, according to further embodiments, the compression ratio Cr of the second pad p2 at the first boundary b1 may be within the range of 15% - 70%, or may be within the range of 30 % - 60%.

Moreover, in Fig. 7, a second boundary b2 by between the intermediate pressure region r1 and the high-pressure region r2 is indicated. According to the illustrated embodiments, the separating pressure P2 at the second boundary b2 is approximately 500 kPa and the compression ratio Cr of the second pad p2 is approximately 67%. According to further embodiments, the separating pressure P2 at the second boundary b2 may be within the range of 250 kPa - 1100 kPa, or may be within the range of 350 kPa - 700 kPa. Moreover, according to further embodiments, the compression ratio Cr of the second pad p2 at the second boundary b2 may be within the range of 35% - 80%, or may be within the range of 57 % - 75%.

As is seen in Fig. 7, the separating pressure P between the two adjacent battery cells c1, c2 increases exponentially with the compression ratio Cr of the second pad p2. As explained with reference to Fig. 4a and Fig. 4b above, battery cells d, c2 are subjected to some degree of swelling during the lifetime of the battery cell c1, c2. That is, the battery cells c1, c2 may swell to occupy a larger volume after a certain time t. Upon swelling, the second pad p2 is compressed to obtain the reduced thickness t2’, as explained with reference to Fig. 4a and Fig. 4b. Obviously, the compression ratio Cr of the second pad p2 increases when the second pad p2 is compressed. Therefore, the battery cells c1, c2 inside the module casing 3 of the battery module 1 may be subjected to considerable higher external pressures exerted onto the battery cells c1 - c11 after a certain time t.

By causing the first pad p1 to obtain the reduced thickness t1’, the external pressures exerted onto the battery cells c1 - c11 is reduced partly because the compression ratio Cr of the second pad p2 is reduced upon a reduction in thickness t1’ of the first pad p1. As clearly seen in Fig. 7, the separating pressure P between the two adjacent battery cells d, c2 decreases significantly upon a reduction in the compression ratio Cr of the second pad p2.

The step of causing 120 the first pad p1 to obtain the reduced thickness t1’ may be performed after a certain number of charging cycles Y1 - Yn of the plurality of battery cells d - d 1. As an alternative, or in addition, the step of causing 120 the first pad p1 to obtain the reduced thickness t1’ may be performed after a certain time has elapsed since manufacturing of the plurality of battery cells c1 - c11, may be performed after a certain time has elapsed since assembly of a battery module 1, 1' comprising the plurality of battery cells c1 - c11, and/or may be performed after a certain time has elapsed since the first use of the plurality of battery cells c1 - c11.

The above-mentioned number of charging cycles Y1 - Yn, and/or times, may be set to values at which it can be estimated that the separating pressure P between the two adjacent battery cells c1, c2 is closed to a separating pressure P2 at the second boundary b2 indicated in Fig. 7.

In other word, according to embodiments herein, the first pad p1 may be caused to obtain the reduced thickness t1’ when it is estimated that the separating pressure P between the two adjacent battery cells c1, c2 is close to a boundary b2 between an intermediate pressure region r1 and a high-pressure region r2.

Moreover, according to embodiments herein, the thickness t1, t2 of the respective first and second pad p1, p2, the elasticity of the second pad p2, and the level of shrinkage of the first pad p1, may be adapted such that the separating pressure P between the two adjacent battery cells c1, c2 reaches a value just above a boundary b1 between a low pressure region r0 and an intermediate pressure region r1 when the first pad p1 is caused to obtain the reduced thickness t1 In this manner, a prolonged lifetime of the plurality of battery cells c1 -c11 can be further ensured.

An initial thickness t1, t2 of the respective first and second pad p1, p2, when the battery module 1, 1’ comprising the first and second pads p1, p2 is assembled, may be a couple of millimetres, such as a respective thickness t1, t2 within the range of 1 - 10 millimetres, or 2 -6 millimetres.

Moreover, according to some embodiments, the second pad p2 is compressed between the first pad p1 and one of the two adjacent battery cells c1, c2 to obtain a reduced thickness t2 upon assembly of the battery module 1, 1’. In other words, according to such embodiments, the second pad p2 may have a greater thickness before assembly of the battery module 1, 1’ and may obtain the thickness t2 indicated in Fig. 4a upon assembly of the battery module 1, 1’. In this manner, conditions are provided for obtaining an advantageous external pressure exerted onto the battery cells c1 - c11 upon assembly of the battery module 1, 1’.

The first pad p1 may be formed a material, such as a polymeric material, which shrinks when the temperature T of the material is increased above the threshold temperature Th. As an alternative, or in addition, the first pad p1 may be formed a material, such as a polymeric material, which at least partially melts when the temperature T of the material is increased above the threshold temperature Th. As indicated above, the first pad p1 may be formed by a material being stiffer than the material of the second pad p2 at temperatures below the threshold temperature Th.

According to the embodiments illustrated in Fig. 4b and Fig. 4c, the first pad p1 obtains a reduced thickness t1’ of approximately 75% when the temperature T of the first pad p1 is increased above the threshold temperature Th. According to further embodiments, the first pad p1 may be configured to obtain a reduced thickness t1’ of at least 30%, or at least 50%, when the temperature T of the first pad p1 is increased above the threshold temperature Th.

According to the illustrated embodiments, the first pad p1 is configured such that the thickness t1’ thereof is at least substantially maintained when the temperature T of the first pad p1 declines from a temperature T between the upper safety temperature limit TL and the threshold temperature Th to a temperature T below the threshold temperature Th. According to further embodiments, the first pad p1 may be configured such that the thickness t1’ thereof changes by less than 15% when the temperature T of the first pad p1 declines from a temperature T between the upper safety temperature limit TL and the threshold temperature Th to a temperature T below the threshold temperature Th. In other words, according to these embodiments, the first pad p1 obtains the reduced thickness t1' in an at least substantially irreversible manner upon the increase in temperature T above the threshold temperature Th.

As mentioned above, the temperature control arrangement 21 illustrated in Fig. 1 may be configured to perform any one of the steps 110, 120, 130 of the method 100 illustrated in Fig. 5 and Fig. 6. In other words, the temperature control arrangement 21 may be configured to: - control the temperature T of the plurality of battery cells c1 - c11 to be within a predetermined temperature range Tr during a plurality of charging cycles Y1 - Yn of the plurality of battery cells c1 - c11, the predetermined temperature range Tr being lower than the threshold temperature Th, and then - cause the first pad p1 to obtain the reduced thickness t1’ by temporarily increasing the temperature T of the plurality of battery cells c1 - c11 to a temperature T between the threshold temperature Th and the upper safety temperature limit TL of the plurality of battery cells c1 - c11.

The temperature control arrangement 21 may be configured to temporarily increasing the temperature T of the plurality of battery cells c1 - c11 by controlling operation of the thermal management system 24, for example by controlling operation of the one or more cooling fans, the one or more thermostatic valves, the one or more coolant heating assemblies, and/or the one or more coolant pumps of the thermal management system 24.

Moreover, the temperature control arrangement 21 may be configured to: control the temperature T of the plurality of battery cells c1 - c11 to be within the predetermined temperature range Tr during a number of following charging cycles Yn+2 - Yn+k of the plurality of battery cells c1 - c11.

As understood from the above, the temperature control arrangement 21 may be configured to control the temperature T of the plurality of battery cells c1 - c11 to be within the predetermined temperature range Tr by controlling operation of the thermal management system 24, for example by controlling operation of the one or more cooling fans, the one or more thermostatic valves, the one or more coolant heating assemblies, and/or the one or more coolant pumps of the thermal management system 24.

It will be appreciated that the various embodiments described for the method 100 are all combinable with the temperature control arrangement 21 as described herein. That is, the temperature control arrangement 21 may be configured to perform any one of the method steps 110, 120, and 130 of the method 100. The temperature control arrangement 21, as referred to herein, may also be referred to as a control arrangement.

Fig. 8 illustrates a computer-readable medium 200 comprising instructions which, when executed by a computer, cause the computer to carry out the method 100 according to some embodiments of the present disclosure. According to some embodiments, the computerreadable medium 200 comprises a computer program comprising instructions which, when the program is executed by a computer, cause the computer to carry out the method 100 according to some embodiments.

One skilled in the art will appreciate that the method 100 of controlling the temperature T of a plurality of battery cells c1 - c11 of a battery module 1 may be implemented by programmed instructions. These programmed instructions are typically constituted by a computer program, which, when it is executed in the temperature control arrangement 21, ensures that the temperature control arrangement 21 carries out the desired control, such as the method steps 110, 120, and 130 described herein. The computer program is usually part of a computer program product 200 which comprises a suitable digital storage medium on which the computer program is stored.

The temperature control arrangement 21 may comprise a calculation unit which may take the form of substantially any suitable type of processor circuit or microcomputer, e.g., a circuit for digital signal processing (digital signal processor, DSP), a Central Processing Unit (CPU), a processing unit, a processing circuit, a processor, an Application Specific Integrated Circuit (ASIC), a microprocessor, or other processing logic that may interpret and execute instructions. The herein utilised expression "calculation unit" may represent a processing circuitry comprising a plurality of processing circuits, such as, e.g., any, some or all of the ones mentioned above.

The temperature control arrangement 21 may further comprise a memory unit, wherein the calculation unit may be connected to the memory unit, which may provide the calculation unit with, for example, stored program code and/or stored data which the calculation unit may need to enable it to do calculations. The calculation unit may also be adapted to store partial or final results of calculations in the memory unit. The memory unit may comprise a physical device utilised to store data or programs, i.e., sequences of instructions, on a temporary or permanent basis. According to some embodiments, the memory unit may comprise integrated circuits comprising silicon-based transistors. The memory unit may comprise e.g., a memory card, a flash memory, a USB memory, a hard disc, or another similar volatile or non-volatile storage unit for storing data such as e.g., ROM (Read-Only Memory), PROM (Programmable Read-Only Memory), EPROM (Erasable PROM), EEPROM (Electrically Erasable PROM), etc. in different embodiments.

The temperature control arrangement 21 is connected to components of the battery module 1, 1', the battery pack 10, and/or the thermal management system 24 for receiving and/or sending input and output signals. These input and output signals may comprise waveforms, pulses, or other attributes which the input signal receiving devices can detect as information and which can be converted to signals processable by the temperature control arrangement 21. These signals may then be supplied to the calculation unit. One or more output signal sending devices may be arranged to convert calculation results from the calculation unit to output signals for conveying to other parts of the vehicle's control system and/or the component or components for which the signals are intended. Each of the connections to the respective components of the of the battery module 1, 1', the battery pack 10, and/or the thermal management system 24 for receiving and sending input and output signals may take the form of one or more from among a cable, a data bus, e.g., a CAN (controller area network) bus, a MOST (media orientated systems transport) bus or some other bus configuration, or a wireless connection.

In the embodiments illustrated, the vehicle 20 comprises a temperature control arrangement 21 but might alternatively be implemented wholly or partly in two or more control arrangements or two or more control units.

Control systems in modern vehicles generally comprise a communication bus system consisting of one or more communication buses for connecting a number of electronic control units (ECUs), or controllers, to various components on board the vehicle. Such a control system may comprise a large number of control units and taking care of a specific function may be shared between two or more of them. Vehicles of the type here concerned are therefore often provided with significantly more control arrangements than depicted in Fig. 1, as one skilled in the art will surely appreciate.

The computer program product 200 may be provided for instance in the form of a data carrier carrying computer program code for performing at least some of the method steps 110, 120, and 130 according to some embodiments when being loaded into one or more calculation units of the temperature control arrangement 21. The data carrier may be, e.g. a CD ROM disc, as is illustrated in Fig. 8, or a ROM (read-only memory), a PROM (programable readonly memory), an EPROM (erasable PROM), a flash memory, an EEPROM (electrically erasable PROM), a hard disc, a memory stick, an optical storage device, a magnetic storage device or any other appropriate medium such as a disk or tape that may hold machine readable data in a non-transitory manner. The computer program product may furthermore be provided as computer program code on a server and may be downloaded to the temperature control arrangement 21 remotely, e.g., over an Internet or an intranet connection, or via other wired or wireless communication systems.

It is to be understood that the foregoing is illustrative of various example embodiments and that the invention is defined only by the appended independent claims. A person skilled in the art will realize that the example embodiments may be modified, and that different features of the example embodiments may be combined to create embodiments other than those described herein, without departing from the scope of the present invention, as defined by the appended independent claims.

As used herein, the term "comprising" or "comprises" is open-ended, and includes one or more stated features, elements, steps, components, or functions but does not preclude the presence or addition of one or more other features, elements, steps, components, functions, or groups thereof.

Claims

1. A battery module (1) comprising: - a module casing (3), a plurality of battery cells (c1 - c11) arranged in the module casing (3), and - at least one pad assembly (5) interposed between two adjacent battery cells (c1, c2) of the plurality of battery cells (c1 - c11), wherein the pad assembly (5) comprises a first pad (p1) configured to shrink to obtain a reduced thickness (t1') when the temperature (T) of the first pad (p1) is increased above a threshold temperature (Th), and wherein the threshold temperature (Th) is lower than an upper safety temperature limit (TL) of the plurality of battery cells (c1 - c11), wherein the threshold temperature (Th) is within the range of 50 - 90 degrees Celsius or is within the range of 60 - 85 degrees Celsius.

2. The battery module (1) according to claim 1, wherein the battery cells (c1 - c11) of the plurality of battery cells (c1 - c11) are configured to operate within a predetermined temperature range (Tr) being lower than the threshold temperature (Th).

3. The battery module (1) according to any one of the preceding claims, wherein the first pad (p1) is configured to obtain a reduced thickness (t1’) of at least 30%, or at least 50%, when the temperature (T) of the first pad (p1) is increased above the threshold temperature (Th).

4. The battery module (1) according to any one of the preceding claims, wherein the first pad (p1) is configured such that the thickness (t1’) thereof changes by less than 15% when the temperature (T) of the first pad (p1) declines from a temperature (T) between the upper safety temperature limit (TL) and the threshold temperature (Th) to a temperature (T) below the threshold temperature (Th).

5. The battery module (1) according to any one of the preceding claims, wherein the pad assembly (5) comprises a second pad (p2), and wherein the first and second pads (p1, p2) together are configured to apply a separating pressure (P) between the two adjacent battery cells (d, c2).

6. The battery module (1) according to claim 5, wherein the second pad (p2) is formed by an elastic material.

7. The battery module (1) according to claim 5 or 6, wherein the second pad (p2) is arranged to expand to obtain an increased thickness (t2”) upon a reduction in thickness ( t1’) of the first pad (p1).

8. The battery module (1) according to claim 5 - 7, wherein the second pad (p2) is compressed between the first pad (p1) and one of the two adjacent battery cells (c1, c2) to obtain a reduced thickness (t2) upon assembly of the battery module (1).

9. The battery module (1) according to claim 5 - 8, wherein the first pad (p1) is formed by a material being stiffer than the material of the second pad (p2) at temperatures below the threshold temperature (Th).

10. The battery module (1) according to any one of the preceding claims, wherein the battery cells (c1 - c11) of the plurality of battery cells (c1 - c11) are prismatic battery cells.

11. A battery pack (10) comprising a number of battery modules (1, 1') according to any one of the preceding claims.

12. A vehicle (20) comprising an electric propulsion machine (33) configured to provide motive power to the vehicle (20) and a battery pack (10) according to claim 11, wherein the battery pack (10) is configured to supply electricity to the electric propulsion machine (33).

13. A temperature control arrangement (21) for a battery module (1), the battery module (1) comprising: - a module casing (3), - a plurality of battery cells (c1 - c11) arranged in the module casing (3), and - at least one pad assembly (5) interposed between two adjacent battery cells (c1, c2) of the plurality of battery cells (c1 - c11), wherein the pad assembly (5) comprises a first pad (p1) configured to shrink to obtain a reduced thickness (t1’) when the temperature (T) of the first pad (p1) is increased above a threshold temperature (Th), and wherein the threshold temperature (Th) is lower than an upper safety temperature limit (TL) of the plurality of battery cells (c1 - c11), and wherein the temperature control arrangement (21) is configured to: - control the temperature (T) of the plurality of battery cells (c1 - c11) to be within a predetermined temperature range (Tr) during a plurality of charging cycles (Y1 - Yn) of the plurality of battery cells (d - c11), the predetermined temperature range (Tr) being lower than the threshold temperature (Th), and then - cause the first pad (p1) to obtain the reduced thickness (t1’) by temporarily increasing the temperature (T) of the plurality of battery cells (c1 - c11) to a temperature (T) between the threshold temperature (Th) and the upper safety temperature limit (TL) of the plurality of battery cells (c1 - c11), wherein the threshold temperature (Th) is within the range of 50 - 90 degrees Celsius or is within the range of 60 - 85 degrees Celsius.

14. A method (100) of controlling the temperature (T) of a plurality of battery cells (c1 - c11) of a battery module (1), the battery module (1) comprising: - a module casing (3), - the plurality of battery cells (c1 - c11) arranged in the module casing (3), and - at least one pad assembly (5) interposed between two adjacent battery cells (c1, c2) of the plurality of battery cells (c1 - c11), wherein the pad assembly (5) comprises a first pad (p1) configured to shrink to obtain a reduced thickness (t1’) when the temperature (T) of the first pad (p1) is increased above a threshold temperature (Th), and wherein the threshold temperature (Th) is lower than an upper safety temperature limit (TL) of the plurality of battery cells (c1 - c11), and wherein the method (100) comprises the steps of: - controlling (110) the temperature (T) of the plurality of battery cells (c1 - c11) to be within a predetermined temperature range (Tr) during a number of charging cycles (Y1 - Yn) of the plurality of battery cells (c1 - c11), the predetermined temperature range (Tr) being lower than the threshold temperature (Th), and then - causing (120) the first pad (p1) to obtain the reduced thickness (t1’) by temporarily increasing the temperature (T) of the plurality of battery cells (c1 - c11) to a temperature (T) between the threshold temperature (Th) and the upper safety temperature limit (TL) of the plurality of battery cells (c1 - c11), wherein the threshold temperature (Th) is within the range of 50 - 90 degrees Celsius or is within the range of 60 - 85 degrees Celsius.

15. The method (100) according to claim 14, wherein the method (100) comprises the step of, after the step of causing (120) the first pad (p1) to obtain the reduced thickness (t1’): - controlling (130) the temperature (T) of the plurality of battery cells (c1 - c11) to be within the predetermined temperature range (Tr) during a number of following charging cycles (Yn+2 - Yn+k) of the plurality of battery cells (c1 - c11).

16. A computer program comprising instructions which, when the program is executed by a computer, cause the computer to carry out the method (100) according to claim 14 or 15.

17. A computer-readable medium (200) comprising instructions which, when executed by a computer, cause the computer to carry out the method (100) according to claim 14 or 15.