Self-extinguishing battery

Abstract

The present invention relates to battery pack (100) comprising a plurality of battery cells (120) coupled together in a predetermined manner for providing a predetermined battery pack voltage, said battery pack (100) comprising: a first housing portion (110a) and a second housing portion (110b) configured to be coupled together to a housing (110), electrical connections (135) provided in said first housing portion (110a) and said second housing portion (110b) configured for electrically connecting one battery cell with at least one other battery cell for providing said predetermined battery pack voltage, at least one extinguishing space (155, 157, 170) at least partially surrounding said plurality of battery cells (120), wherein said at least one extinguishing space (155, 157, 170) is configured to be in fluid connection with a fire extinguishing unit (150a, 150b, 160).

Description

SELF-EXTINGUISHING BATTERY Technical field

[0001] The present invention relates generally to a battery pack, in particular itrelates to a self-extinguishing battery pack.Background art

[0002] In recent years, with increasingly wide application of lithium-ion batteries,the lithium-ion batteries have been widely used in energy storage power supply systems such as water-power stations, thermal power stations, wind power stations, and solar power stations, and in a plurality of fields such as electric tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, and aerospace. Due to great expansion of the application fields of the lithium-ion batteries, higher requirements are imposed on energy density, cycling performance, high-temperature performance (especially high-temperature rate performance), and the like of the lithium-ion batteries.

[0003] When the battery cell is overcharged, over high temperature, internalshort circuit, etc., thermal runaway may occur. At this time, the burning ofthe battery cell will release a large amount of heat. If it is not handled in time orhandled improperly, it may cause the entire battery system to catch fire and evenexplode, which may be harmful not only for the battery itself but also for equipment and / or persons in its vicinity.

[0004] There is need for a battery that provides for increased safety.Summary of invention

[0005] It is an object of the present invention to provide a battery which iscapable of handling thermal runaway more effectively than known batteries.

[0006] In a first aspect of the present invention it is provided a battery packcomprising a plurality of battery cells coupled together in a predetermined manner for providing a predetermined battery pack voltage, said battery pack comprising: a first housing portion and a second housing portion configured to be coupledtogether to form a housing, electrical connections provided in said first housing portion and said second housing portion configured for electrically connecting one battery cell with at least one other battery cell for providing said predetermined battery pack voltage, at least one extinguishing space at least partially surrounding said plurality of battery cells, wherein said at least one extinguishing space is configured to be in fluid connection with a fire extinguishing unit.

[0007] The advantage of the present invention is that battery fires may becontrolled efficiently at an early stage.

[0008] In various example embodiments of the present invention said fireextinguishing unit is provided within at least one of said first housing portion and / or said second housing portion.

[0009] The advantage of these embodiments is that the number of extinguishingunits may be customized depending on space, number of battery cells etc.

[0010] In various example embodiments of the present invention said fireextinguishing unit is provided external to at least one of said first housing portion and / or said second housing portion.

[0011] The advantage of these embodiments is that the size of the battery packmay be minimized.

[0012] In various example embodiments of the present invention said firsthousing portion and said second housing portion is made of ceramic material.

[0013] The advantage of these embodiments is that in case of fire, the fire maybe confined to a limited volume.

[0014] In various example embodiments of the present invention said electricalconnections is provided on a printed circuit board (PCB) (130, 130a, 130b).

[0015] The advantage of these embodiments is that the assembly of the batterypack may be simplified.

[0016] In various example embodiments of the present invention a firstextinguishing space may be provided on a first side of said PCB and a second extinguishing space may be provided on a second side of said PCB. The PCB may be provided with at least one flow path between said first and second extinguishing space.

[0017] The advantage of these embodiments is that the PCB is not forming abarrier for the fire extinguishing agent within the battery pack.

[0018] In various example embodiments of the present invention said fireextinguishing unit comprises fire extinguishing agent in the form of a gas provided in a pressurized gas container.

[0019] The advantage of these embodiments is that said unit may be arrangedexternal to said battery pack.

[0020] In various example embodiments of the present invention said first and / orsecond housing portion comprising at least one positive battery pack terminal and at least one negative battery pack terminal.

[0021] The advantage of these embodiments is that the battery pack maycomprise a plurality of battery terminals defining a plurality of battery voltages.

[0022] In various example embodiments of the present invention saidextinguishing unit comprises a fire extinguishing agent in solid form comprising at least 25% by weight potassium. In various example embodiments the fire extinguishing agent in solid form may comprise at least 50% by weight or even at least 80% by weight potassium.

[0023] The advantage of these embodiments is that fires in Li-ion basedbatteries may be extinguished.

[0024] In various example embodiments of the present invention the batterypack further comprising an actuator configured to activate said extinguishing unit.

[0025] The advantage of these embodiments is that various types of actuatorsmay be used such as fuses, ignition units or valves. The actuator may be triggered by temperature.

[0026] In various example embodiments of the present invention said batterypack further comprising a battery management system (BMS) provided within one of said first or second housing portion.

[0027] The advantage of these embodiments is that the BMW may be integratedone PCB which also provides for the electrical connection between at least two battery cells.

[0028] In another aspect of the present invention it is provided a batterycomprising two or more battery packs coupled together for forming a predetermined battery voltage. Brief description of drawings

[0029] The invention is now described, by way of example, with reference to theaccompanying drawings, in which:

[0030] Fig. 1 depicts an exploded perspective view of an example embodimentof a battery pack according to the present invention.

[0031] Fig. 2 schematically depicts an example embodiment of a printed circuitboard with predetermined battery positions.

[0032] Fig. 3 depicts a cross sectional view of an example embodiment of abattery pack according to the present invention.

[0033] Fig. 4 depicts a cross sectional view of another example embodiment ofa battery pack according to the present invention.

[0034] Fig. 5a depicts a cross sectional view of still an example embodiment ofa battery pack according to the present invention.

[0035] Fig. 5b depicts a cross sectional view of yet another exampleembodiment of a battery pack according to the present invention. Description of embodiments

[0036] The proposed invention discloses a self-extinguishing battery pack. In afirst example embodiment of the present invention a battery pack 100 comprising a plurality of battery cells 120 coupled together in a predetermined manner for providing a predetermined battery pack voltage. Said battery pack 100 comprising a first housing portion 110a and a second housing portion 110b, wherein said first and second housing portions are configured to be coupled together to form a housing 110. The battery pack further comprising electrical connections provided in said first housing portion 110a and said second housing portion 110b configured for electrically connecting one battery cell with at least one other battery cell for providing said predetermined battery pack voltage. Said battery pack further comprising at least one extinguishing space 155, 157, 170 at least partially surrounding said plurality of battery cells 120. Said at least one extinguishingspace 155, 157, 170 is configured to be in fluid connection with a fire extinguishingunit 150a, 150b, 160.

[0037] In figure 1 it is disclosed an exploded perspective view of an exampleembodiment of a battery pack 100 according to the present invention. The battery pack 100 comprises a plurality of battery cells 120 with a predetermined battery cell voltage. The battery cell voltage may for instance be 3,6V but may of course have any other voltage such as 2,4V, 3,0V, 4,2V etc. The battery cells 120 are provided inside a housing 110 comprising a first housing portion 110a and a second housing portion 110b. The battery cells 120 are stacked in a predetermined manner in order to achieve a predetermined output voltage of the battery pack 100. Depending on the battery cell voltage, number of battery cells and / or stacking design the battery pack 100 may be designed to have various predetermined output voltage. Provided in said first housing portion 110a and said second housing portion 110b electrical connections are provided for achieving said predetermined battery pack voltage. The battery pack 100 is only providing output voltage when said first and second housing portions 110a and 110b respectivelyare put together with battery cells provided inside said housing 110. The battery pack 100 may comprise at least one positive battery terminal and at least one negative battery terminal, which terminals may be provided at any position on the outside of said housing 110. In various example embodiments said battery pack 100 may comprise a plurality of positive battery terminals and a plurality of negative battery terminals. I first pair of positive and negative battery terminalsmay be configured to represent the full voltage of the battery pack 100. A secondpair of positive and negative battery terminals may be configured to represent a portion of the full battery voltage of the battery pack 100. Said portion may for instance be 75%, 50% or 25% of the full battery voltage.

[0038] The first housing portion 110a and the second housing portion 110b maybe made of ceramic, glass or metal.

[0039] Figure 2 schematically depicts an example embodiment of a printedcircuit board 130 with predetermined battery positions. The printed circuit board may have various electrical connections configured to achieve a desired voltage of the battery pack 100. In various example embodiment a first printed circuit board 130a is provided in said first housing portion 110a and a second printed circuitboard 130b is provided in said second housing portion 110b. The first and secondprinted circuit board may be designed in such a way that when arranged on eachside of said plurality of battery cells 120 it will create a predetermined battery packvoltage between a pair of positive and negative battery terminals.

[0040] Figure 3 depicts a cross sectional view of an example embodiment of anassembled battery pack 100 according to the present invention. The battery pack100 comprises a housing 110 provided with a plurality of stacked battery cells 120.A first housing portion 110a comprises a first PCB 130a. In various exampleembodiment said PCB may be an electrical wiring harness providing electricalconnection in a predetermined manner between the battery cells 120. The first housing portion 110a further comprises a first fire extinguishing unit 150a. The firstfire extinguishing unit 150a is fluidly coupled to at least one fire extinguishingspace 155a, 157a. The battery cells 120 may be at least partially surrounded bysaid fire extinguishing space 155a, 157a. The fire extinguishing unit 150a isconfigured to transmit a fire extinguishing agent through said fire extinguishing space 155a, 157a. The fire extinguishing agent is configured to extinguish a firestarted at any one of the battery cells 120 in said battery pack 100. The fireextinguishing agent may comprise at least 25% by weight potassium. In various example embodiments the fire extinguishing agent may comprise at least 40% by weight potassium. In various example embodiments the fire extinguishing agentmay comprise at least 50% by weight potassium. In various example embodimentsthe fire extinguishing agent may comprise at least 80% by weight potassium.

[0041] The fire extinguishing unit 150a, 150b may be provided accessible fromthe outside of said housing 110. The fire extinguishing unit 150a, 150b may forinstance be located behind a lid provided on the outside of said housing 110.

[0042] In figure 3 a second housing portion 110b is almost identical to the firsthousing portion 110a. The first and second housing portions 110a and 110brespectively, may be releasable attached to each other by means of one or a plurality of screw joints, rivets or similar. The second housing portion 110b is infigure 3 depicted to comprise a second extinguishing unit 150b fluidly coupled to atleast one fire extinguishing space 155b, 157b in a similar manner as described inconnection with said first housing portion 110a. ‘The fire extinguishing space 157a in said first housing portion 110a is configured to line up with a fire extinguishing space 157b in said second housing portion 110b for allowing continuous flow of an extinguishing agent.

[0043] The first PCB 130a comprises thorough holes 190a for allowing saidextinguishing agent to flow from one side of said first PCB 130a to another side of said fist PCB 130. Similarly, the second PCB 130b comprises thorough holes 190b for allowing said extinguishing agent to flow from one side of said second PCB 130bn to another side of said second PCB 130b.

[0044] The first and second PCB 130a and 130b respectively, may comprisesupport structures 180a, 180b for supporting said battery cells. The support structures 180a, 180b simplifies the stacking of battery cells 120 and ensures thatthe battery cells are provided in the correct position for electrical connection.

[0045] An extinguishing agent from said first and second extinguishing unit 150aand 150b respectively may be configured to fill the fire extinguishing space 155a,155b, 157a, 157b inside said housing 110. The battery cells 120 are stacked in thehousing 110 with a predetermined distance from each other, which distance allowssaid extinguishing agent to reach each individual cell. The first PCB 130a and thesecond PCB 130b may comprise at least one flow path 190a, 190b allowing saidextinguishing agent to pass through said PCB 130a, 130b from a first side facingtowards an outside of said housing 110 to a second side facing towards an inside of said housing 110. The extinguishing agent in said extinguishing unit may betriggered by temperature. The extinguishing agent may be in solid form. Theextinguishing agent may be in powder form. The powder formed extinguishing agent may be blended with a power formed explosive agent. The explosive agent may be triggered by temperature and / or ignition. The powder formed extinguishing agent and the powder formed explosive agent may be pressed together into a cake.

[0046] Figure 4 depicts a cross sectional view of another example embodimentof a battery pack 100 according to the present invention. Here the extinguishingunit 160 is provided external to said battery pack 100. The extinguishing unit 160is removably attached to the extinguishing space 155. A temperature sensor may trigger a valve to open if the temperature has reached a predetermined level. In figure 4 the first housing portion 110a is different to the second housing portion110b. The first housing portion 110a comprises extinguishing space 157a and 155whereas the second housing potion 110b only comprises extinguishing space 157b. Extinguishing space 157a in the first housing portion is mating to an extinguishing space 157b in said second housing portion 110b in order to form a passage for extinguishing agent. The battery cells 120 are electrically coupled to each other in a predetermined manner via the first PCB 130a and the second PCB130b. Here the first PCB 130a has flow path(s) or thorough holes 190a allowingsaid extinguishing agent to pass from said extinguishing space 155 to said extinguishing space 157a.

[0047] Figure 5a depicts a cross sectional view of still an example embodimentof a battery pack 100 according to the present invention. Here the firstextinguishing unit 150a is provided in an extinguishing space 170a and saidsecond extinguishing unit 150b is provided in an extinguishing space 170b. Theextinguishing space 170a is fluidly coupled to the extinguishing space 157a viathorough holes 190a in said first PCB 130a. The extinguishing space 157a and157b fluidly couples extinguishing space 170a to said extinguishing space 170b.Extinguishing space 170b may be provided with at least one extinguishing unit 150b and extinguishing space 170a may be provided with at least one extinguishing unit 150a. The second PCB 130b is also provided with thorough holes 190b allowing free passage of extinguishing agent from said extinguishingspace 170b to said extinguishing space 157b. The first and second PCB 130a,130b may comprise support structures 180a, 180b for said battery cells120.

[0048] Fig. 5b depicts a cross sectional view of yet another exampleembodiment of a battery pack 100 according to the present invention. The only difference between figure 5b and figure 5a is that figure 5b has a second housing portion 110b which is different to said first housing portion 110a. In figure 5b theextinguishing unit 150a is provided in the extinguishing space 170a is said firsthousing portion 110a. The second housing portion 110b is in this exampleembodiment void of any extinguishing unit but may provide for extinguishing space 157b at least partially surrounding said battery cells.

[0049] The fire extinguishing agent may comprise a force producing meansmixed with extinguishing substance. The extinguishing agent may be transformed from a solid form to an aerosol in the presence of heat above an undesired level.The force producing means and said fire extinguishing substance may be mixedtogether for forming a solid substance. When said force producing means is ignited by an ignition unit or heat sensitive means, said force producing means will explode and disintegrate the fire extinguishing substance into fine particles and fillthe extinguishing space 170, 170a, 170b, 157a, 157b within said housing 110.

[0050] In various example embodiments said fire extinguishing unit 150a, 150bmay be embedded in the first and / or the second housing portion 110a 110b. Invarious example embodiments said fire extinguishing unit 150a, 150b may beprovided in any extinguishing space 170, 170a, 170b, 157a, 157b of said first andor second housing portion 110a, 110b. A trigger for said extinguishing unit may be a fuse or a trigger unit. The trigger unit may be electrically coupled to at least one battery cell 120 for powering said trigger unit. The trigger unit may be coupled to a BMS. The BMS may measure the temperature of the battery pack 100. Thetemperature may be measured by a separate unit with respect to said BMS. TheBMS may be integral with or eternal to said battery pack 100.

[0051] The fire extinguishing substance may comprise monoammoniumphosphate. Alternatively said fire extinguishing substance may comprise sodiumbicarbonate. The fine particles (aerosols) in the fire extinguishing substance absorbs heat from the fire, so called heterogenous catalytic reaction. The aerosolmay be in the form of a potassium compound. Potassium radicals may stop thechemical reactions taking place in a fire by neutralizing hydrogen, oxygen and hydroxy radicals in the flame. The fine fire extinguishing particles is a very effective extinguishing means. Small particles will be floating in the ambient air a longer time compared to larger particles. The prolonged floating time maycontribute to an increased protection against re-ignition. In various exampleembodiments the potassium compound may be at least 25% by weight of said extinguishing substance. In various example embodiments the potassium compound may be at least 40% by weight of said extinguishing substance. Invarious example embodiments the potassium compound may be at least 50% byweight of said extinguishing substance. In various example embodiments thepotassium compound may be at least 80% by weight of said extinguishing substance.

[0052] The force producing means may for instance be nitrogen sulfide,cadmium azide, sodium fulminate, potassium fulminate, zinc azide or similar. Theforce producing means and said fire extinguishing substance may be mixedtogether with or without a binding element for forming said solid substance. Said binding element may be shellac, glucose, ester gum or similar.

[0053] In various example embodiments the extinguishing agent may comprise:potassium nitrate with a concentration about 50-75%, strontium nitrate with a concentration about 20-35%, melamine with a concentration about 10-20%, phenolic resin with a concentration about 5-15% and sodium hydrogen tartrate monohydrate with a concentration about 5-15%.

Claims

CLAIMS 1. A battery pack (100) comprising a plurality of battery cells (120) coupledtogether in a predetermined manner for providing a predetermined batterypack voltage, said battery pack (100) comprising: a first housing portion (110a) and a second housing portion (110b) configured to be coupledtogether to form a housing (110), electrical connections provided in said firsthousing portion (110a) and said second housing portion (110b) configuredfor electrically connecting one battery cell with at least one other battery cell for providing said predetermined battery pack voltage, at least one extinguishing space (155, 155a, 155b, 157a, 157b, 170a, 170b) at leastpartially surrounding said plurality of battery cells (120), wherein said atleast one extinguishing space (155, 155a, 155b, 157a, 157b, 170a, 170b) isconfigured to be in fluid connection with a fire extinguishing unit (150a,150b, 160).

2. The battery pack according to claim 1, wherein said fire extinguishing unit150a, 150b) is provided within at least one of said first housing portion (110a) and / or said second housing portion (110b).

3. The battery pack according to claim 1, wherein said fire extinguishing unit150a, 150b) is provided external to at least one of said first housing portion (110a) and / or said second housing portion (110b).

4. The battery pack according to any one of claim 1-3, wherein said firsthousing portion and said second housing portion is made of ceramic material.

5. The battery pack according to any one of claim 1-4, wherein said electricalconnections is provided on a printed circuit board (PCB) (130, 130a, 130b).

6. The battery pack according to any one of claim 5, wherein a firstextinguishing space is provided on a first side of said PCB and a second extinguishing space is provided on a second side of said PCB, wherein said PCB is provided with at least one flow path between said first and second extinguishing space.

7. The battery pack according to any one of claim 1-6, wherein said fireextinguishing unit comprises fire extinguishing agent in the form of a gasprovided in a pressurized gas container.

8. The battery pack according to any one of the preceding claims, whereinsaid first and / or second housing portion comprising at least one positive battery pack terminal and at least one negative battery pack terminal.

9. The battery pack according to any one of the preceding claims, whereinsaid extinguishing unit comprises a fire extinguishing agent in solid form comprising at least 25% by weight potassium.

10. The battery pack according to claim 9, wherein said battery cells are Li-ionbattery cells.

11. The battery pack according to any one of the preceding claims, the batterypack further comprising an actuator configured to activate said extinguishing unit.

12. The battery pack according to claim 11, wherein the extinguishing unit isactivated by an ignition unit and / or a fuse.

13. The battery pack according to any one of the preceding claims, furthercomprising a battery management system (BMS) provided within one of said first or second housing portion (110a, 110b).

14. A battery comprising two or more battery packs according to any one ofclaim 1-8 coupled together for forming a predetermined battery voltage.

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