WO2017000297A1

WO2017000297A1 - Battery group

Info

Publication number: WO2017000297A1
Application number: PCT/CN2015/083141
Authority: WO
Inventors: 李翔; 李辉
Original assignee: 微宏动力系统（湖州）有限公司
Priority date: 2015-07-02
Filing date: 2015-07-02
Publication date: 2017-01-05
Also published as: CN107851861A; CN107851861B

Abstract

A battery group, comprising a first battery container (1), the first battery container (1) being sealed off from the outside, a second battery container (2) provided inside the first battery container (1), the second battery container (2) being sealed off from the first battery container (1), a sealing liquid (24) and a battery module (21) provided inside the second battery container (2), the battery module (21) being immersed in the sealing liquid (24), and a cooling liquid provided between the second battery container (2) and the first battery container (1), the latent heat of vaporization of the cooling liquid (3) being higher than the heat capacity or the latent heat of vaporization of the sealing liquid (24). The technical solution can effectively suppress the spread of thermal runaway of a battery group.

Description

Battery pack

Technical field

A battery pack including a temperature control system is disclosed.

Background technique

The power system of an energy storage/electric vehicle is composed of a plurality of battery modules, and the battery module is composed of a plurality of battery cells. Due to the pursuit of the energy density of the battery pack, the battery cells in the battery module are arranged so tightly that the heat inside the battery module is easily accumulated, especially in the middle of the entire module, and the temperature is often higher than other parts. When the heat of some of the battery cells in the module accumulates to a certain extent, thermal runaway may occur. Moreover, thermal runaway can spread inside the battery module, causing the temperature of other normally operating battery cells to rise rapidly, which causes thermal runaway of the entire battery module, which is extremely dangerous, especially in a closed battery box.

Patent Application No. CN201280043177.9, entitled "Battery Pack Fire Extinguishing Device" discloses a device capable of suppressing a fire in the battery pack when the battery pack is on fire. The fire extinguishing device includes: a fire detecting sensor for detecting whether the battery pack is on fire; a fire extinguishing agent container containing a fire extinguishing agent in an inner space thereof; and a control unit for detecting a fire when the fire detecting sensor is detected by the fire detecting sensor The fire extinguishing agent in the fire extinguisher container is injected into the interior of the battery pack.

The fire detection sensor in the patent is used to detect whether the battery pack is on fire or not, and proves that the fire extinguishing device starts to work after an open flame occurs in the battery pack. In fact, the battery pack in the early stage of thermal runaway is characterized by smoke, and the temperature of the battery cell showing obvious symptoms is rapidly rising. Once a battery cell begins to run out of heat, it continuously generates heat and may adjacent the battery. The monomer is heated above the critical temperature of thermal runaway, causing these healthy battery cells to enter thermal runaway. This phenomenon can quickly spread and generate heat until other adjacent battery cells are heated to a thermal runaway state.

Patent application No. CN201410186474.X, entitled "An electric vehicle high waterproof insulated battery box", discloses a battery box comprising a sealed box body and a plurality of battery units in the box body, and further comprising a box A heat sink connected to the body and connected to several battery cells. Each battery unit is provided with a heating device, and a battery box controller connected to the heating device through the control circuit is further disposed in the box body, and a hollow heat dissipation plate is designed to dissipate heat for each battery unit module, thereby ensuring uniform heat dissipation of the battery unit module and improving Cooling efficiency. The technical solution disclosed in the patent can solve the problem of temperature uniformity of the battery cells in the normal working state of the battery pack, but since the heat dissipation plate plays a role of heat conduction, once a battery cell occurs When the heat is out of control, the heat is quickly transferred to other normal battery cells, causing the thermal runaway to spread rapidly.

In the prior art, in order to better control the temperature of the battery pack, there is a cooling loop between the battery cells to reduce the temperature difference of each battery cell in the battery module, and there is also a fire extinguishing device that is connected outside the battery box. . The installation of a fire extinguishing device or the like in the battery system is only a remedy after the thermal runaway of the battery pack, and the thermal runaway cannot be effectively controlled in the bud. In the battery system, the cooling device is usually designed with air cooling and liquid cooling, and the air volume is relatively poor. In order to achieve better heat dissipation, the liquid battery is often immersed in the cooling liquid for the battery. For the safety performance of the group, liquids with better insulation properties are usually selected, and these insulation coolants have lower heat capacity values and higher boiling points, and it is difficult to undergo phase change at the thermal runaway temperature of the battery pack, when the temperature rises sharply. It is difficult to take the heat generated quickly. What is even more unfavorable is that if the temperature of the insulating coolant rises rapidly, it will also have the effect of “oil bath”, which will also heat other normal working batteries to the state of thermal runaway, which will have more serious consequences.

Taking active remedial measures after thermal runaway of the battery pack is a way to control thermal runaway. Although the above remedies can have certain effects and will not pose serious dangers, the battery pack that has been out of control after thermal runaway will not work properly and cause serious damage. If the thermal runaway can be suppressed in the germination state during the early temperature rise, not only the occurrence of the danger is controlled, but also the unnecessary loss is greatly reduced.

Summary of the invention

An object of the present invention is to provide a battery pack including a first battery case, the first battery case is sealed with respect to the outside, a second battery case is disposed in the first battery case, and the second battery case is opposite to the first battery case a battery case is sealed, a battery module and a sealing liquid are disposed in the second battery box, the battery module is at least partially immersed in the sealing liquid, and a cooling liquid is disposed between the second battery box and the first battery box, the cooling The latent heat of vaporization of the liquid is higher than the heat capacity of the blocking liquid or the latent heat of vaporization. .

The second battery case is sealingly disposed within the first battery case, the openings may be in the same direction to facilitate loading of the components and sealing of the openings, and the second battery case acts as a separate enclosed space within the first battery case.

Preferably, the second battery box is isolated from the first battery box, the second battery box is sealed with respect to the first battery box, and the battery module and the sealing liquid are disposed in the second battery box, the battery The module is at least partially immersed in the sealing liquid to facilitate heat dissipation and temperature uniformity of the battery module, and to prevent external moisture from damaging the electrical components.

In the present invention, a cooling liquid is disposed between the outer wall of the second battery case and the inner wall of the first battery case, and the latent heat of vaporization of the cooling liquid is higher than the heat capacity of the sealing liquid or the latent heat of vaporization. Therefore, when some of the batteries in the battery pack are out of control and the temperature reaches the vaporization temperature of the coolant, the coolant can absorb a large amount of heat through the phase change, thereby improving the heat dissipation effect of the entire battery pack.

Preferably, the second battery box is provided with a temperature control break point, and the temperature control break point forms a hole when the temperature reaches a preset temperature or higher, so that the coolant enters the second battery box.

According to an embodiment of the present invention, the temperature control break point is a low melting point alloy or a low melting point polymer, and the melting point of the low melting point alloy or the low melting point polymer is between 70 and 150 ° C; more preferably the low The melting point alloy or the low melting point polymer has a melting point between 70 and 130 °C. The low melting point alloy is at least one selected from the group consisting of Ga, In, Sn, Bi, Pb, Cd, and Zn. The low melting point polymer is selected from the group consisting of POE (copolymer of ethylene and butene), EVA (copolymer of ethylene and acetic acid), ABS (acrylonitrile-butadiene-styrene copolymer), PU (polyurethane) At least one of ester), PA (nylon), and CPVC (chlorinated polyvinyl chloride).

The preset temperature is between 70 ° C and 150 ° C depending on the normal operating temperature range of the battery pack; further, the preset temperature is between 80 ° C and 130 ° C. According to an embodiment of the invention, the preset temperature is 100 ° C; according to another embodiment of the invention, the preset temperature is 130 ° C.

According to the object of the present invention, in order to allow the coolant to smoothly enter the second battery box after the temperature control breaks the hole, the liquid level of the coolant is higher than the liquid level of the sealing liquid, or the hydraulic pressure of the coolant Higher than the hydraulic pressure of the blocking liquid.

When the battery pack is not working properly, the rapidly rising temperature causes a phase change in the coolant between the first battery case and the second battery case. Or, after the hole has been formed, the coolant entering the second battery case is more likely to absorb heat and undergo a phase change. At this time, for the safety of the entire battery pack, a pressure relief valve is disposed on the first battery box and/or the second battery box, and preferably a one-way pressure relief valve is provided, so that the gas produced by the cooling liquid phase is after a certain pressure is reached. It can be quickly discharged to further improve safety performance. Preferably, the pressure relief valve disposed on the second battery case is in direct communication with the outside, rather than in communication with the first battery case.

In addition, the first battery box may be provided with a liquid inlet and a liquid outlet, and the coolant may be stored in the coolant container and enter the tank through the liquid inlet provided on the first battery box.

The sealing liquid in the present invention comprises an insulating flame-retardant liquid having a freezing point lower than -30 ° C and a decomposition temperature higher than 70 ° C.

The sealing liquid is a cooling liquid with insulation and flame retardant properties, and has a freezing point below -30 ° C. A decomposition temperature higher than 70 °C. The normal operating temperature of the battery pack can be close to 60 ° C, so the blocking solution cannot be decomposed below 70 ° C.

According to another embodiment of the present invention, the sealing liquid in the present invention comprises an insulating flame-retardant liquid having a freezing point lower than -30 ° C and a boiling point higher than 70 ° C.

The blocking liquid may be selected from at least one of silicone oil, transformer oil, chlorofluorocarbon, fluorohydrocarbon, chlorinated hydrocarbon, and hydrofluoroether.

Silicone oil, transformer oil, etc. have good insulation properties and high stability. Immerse the battery module and electrical components in the sealing liquid to avoid external moisture damage and prolong the service life; and also play a role of heat conduction, which is conducive to uniform temperature inside the battery pack.

In a more preferred embodiment, the boiling point of the cooling liquid is between 70 and 150 °C.

The cooling liquid in the present invention is selected from at least one of water and an aqueous solution, wherein the aqueous solution may be selected from an aqueous solution of an alcohol, and the alcohol may be selected from the group consisting of ethylene glycol, ethylene glycol, propylene glycol, and 1, At least one of 3-butanediol, hexanediol, diethylene glycol, and glycerin, the aqueous solution of the above substance can effectively lower the freezing point and improve the workability in a low temperature environment.

Under normal working conditions, the second battery box and the first battery box are isolated from each other, that is, the sealing liquid in the second battery box and the coolant between the first battery box and the second battery box are isolated from each other. The coolant containing water does not enter the second battery box and affects the insulation performance of the battery module. When the battery module is not working normally, the temperature rises to a preset temperature, and the temperature control point set on the second battery box forms a hole, so that the second battery box and the first battery box communicate with each other, and the coolant quickly flows into the first In the second battery case, the phase change of the coolant effectively controls the temperature of the battery module below the runaway temperature.

Preferably, the second battery case is the same as the opening of the first battery case, and the first battery case is sealed, so that the opening of the second battery box can also be sealed at the same time, which is convenient for installation and is beneficial to the whole. The energy density of the battery pack.

According to another embodiment of the present invention, the first battery box is provided with a liquid outlet and a liquid inlet, and the liquid outlet and the liquid inlet are preferably disposed above the liquid level of the coolant.

Since the coolant disposed between the first battery case and the second battery case is limited, in the case where a serious thermal runaway occurs in the battery module, there may be a case where the coolant is insufficient to effectively control the temperature rise. After the liquid outlet and the liquid inlet are arranged on the first battery box, the coolant is circulated, which can take away the heat generated by the battery module and quickly replenish the coolant in the first battery box, which is more favorable for thermal runaway. The control controls the temperature of the battery module to avoid more serious events.

For the stability of the entire battery pack, a support device is disposed between the second battery case and the first battery case, and the arrangement of the support device should not affect the free circulation of the coolant.

Preferably, the battery module is placed upside down in the second battery case such that the tabs of the battery module are submerged in the blocking liquid. When the battery cell is placed upside down, the battery cell is placed with the ear facing down, and the tab can be immersed in the blocking liquid with less blocking liquid. For the battery unit, the calorific value of the ear is relatively large, and it is immersed in the blocking liquid, the heat dissipation effect is better, and the insulation of the battery module is more favorable.

For flexible packaging batteries, the position of the tabs of the ear is relatively easy to break. The active material inside the battery is easier to flow out from the break. Inverting the battery unit helps to reduce leakage of exposed substances in the air. Leaks, allowing it to flow quickly into the blocking fluid, improving safety.

Preferably, the second battery box is provided with as many temperature control break points as possible. In the case of thermal runaway of individual battery cells in the battery module, the temperature rises very fast, and as many temperature control points as possible can quickly form multiple holes in a short time, so that as much coolant as possible Entering the second battery box, the rapidly rising temperature is effectively suppressed.

After using the technical solution disclosed by the present invention, the temperature of the battery module is more uniform, and the local temperature accumulation is reduced. When some batteries in the battery module have problems, a large amount of heat is generated to cause the local temperature to rise rapidly, so that the temperature control breakpoint disposed on the second battery case forms a hole, and the coolant quickly enters the second battery box to the battery module. Heat dissipation allows the temperature inside the battery pack to be effectively controlled, preventing the spread of thermal runaway. Even if the incoming coolant is not sufficient to fully control the spread of thermal runaway, the spread of thermal runaway can be greatly delayed, minimizing losses.

DRAWINGS

1 is a schematic structural view of an embodiment of a battery pack disclosed in the present invention;

2 is a schematic structural view of another embodiment of the battery pack disclosed by the present invention;

3 is a schematic structural view of another embodiment of a battery pack disclosed by the present invention;

4 is a schematic structural view of another embodiment of the battery pack disclosed by the present invention;

Among them, 1. First battery box, 11. Box cover, 12. Liquid inlet, 13. Liquid outlet, 2. Second battery box, 21. Battery module, 22. Temperature control break point, 23. One-way discharge Pressure valve, 24. sealing liquid, 3. coolant, 31. support device.

Implementation

Example 1

As shown in FIG. 1, the present invention discloses a battery pack including a first battery case 1, the first battery case 1 including a case cover 11, and the first battery case 1 is sealed with respect to the outside. A second battery case 2 is disposed in the first battery case 1, the first battery case 1 and the second battery case 2 share a case cover 11, and the second battery case 2 is sealed with respect to the first battery case 1.

The second battery case 2 is provided with a sealing liquid 24 and a battery module 21, and the battery module 21 is placed upside down in the second battery case 2, and the tabs of the battery module 21 are immersed in the sealing liquid 24, and the sealing liquid 24 is silicone oil.

In addition, a cooling liquid 3 is further disposed between the second battery case 2 and the first battery case 1, and the cooling liquid 3 is water, that is, the second battery case 2 is immersed in the cooling liquid 3, and the temperature control is set on the second battery case 2 At point 22, the temperature control break point 22 forms a hole in the temperature above 90 ° C, so that the coolant 3 can enter the second battery case 2.

The liquid outlet 13 and the liquid inlet 12 are provided in the first battery case 1.

A supporting device 31 is disposed between the second battery case 2 and the first battery case 1. The supporting device 31 supports the second battery case 2 to maintain a fixed interval from the first battery case 1 without affecting the cooling liquid 3. Circulation.

Example 2

The second battery case 2 is provided with a sealing liquid 24 and a battery module 21, and the battery module 21 is placed upside down in the second battery case 2, and the tabs of the battery module 21 are immersed in the sealing liquid 24, and the blocking liquid 24 is a hydrofluoroether.

In addition, a cooling liquid 3 is further disposed between the second battery case 2 and the first battery case 1, and the cooling liquid 3 is water, that is, the second battery case 2 is immersed in the cooling liquid 3, and the temperature control is set on the second battery case 2 At point 22, the temperature control break point 22 forms a hole at a temperature above 130 ° C, so that the coolant 3 can enter the second battery case 2.

A supporting device 31 is disposed between the second battery case 2 and the first battery case 1. The supporting device 31 supports the second battery case 2 to maintain a fixed interval from the first battery case 1 without affecting the cooling liquid. 3 Circulation.

Example 3

As shown in FIG. 2, the present invention discloses a battery pack including a first battery case 1, the first battery case 1 including a case cover 11, and the first battery case 1 is sealed with respect to the outside. A second battery case 2 is disposed in the first battery case 1, the first battery case 1 and the second battery case 2 share a case cover 11, and the second battery case 2 is sealed with respect to the first battery case 1.

In addition, a cooling liquid 3 is further disposed between the second battery case 2 and the first battery case 1, the cooling liquid 3 is an aqueous solution of ethylene glycol, and the second battery case 2 is immersed in the cooling liquid 3. The second battery case 2 is a box wall. a polymer having a melting temperature between 90 ° C and 120 ° C, when an abnormality causes an increase in temperature and reaches a melting temperature of the wall of the second battery case 2, the wall of the second battery case 2 is quickly broken, so that The coolant 3 enters the second battery case 2.

Example 4

As shown in FIG. 3, the present invention discloses a battery pack including a first battery case 1, the first battery case 1 including a case cover 11, and the first battery case 1 is sealed with respect to the outside. A second battery case 2 is disposed in the first battery case 1, the first battery case 1 and the second battery case 2 share a case cover 11, and the second battery case 2 is sealed with respect to the first battery case 1.

In addition, a cooling liquid 3 is further disposed between the second battery case 2 and the first battery case 1, and the cooling liquid 3 is an aqueous solution of propylene glycol, that is, the second battery case 2 is immersed in the cooling liquid 3, and the second battery case 2 is provided with a temperature. By controlling the break point 22, the temperature control break point 22 forms a hole at a temperature above 100 ° C, so that the coolant 3 can enter the second battery case 2.

A supporting device 31 is disposed between the second battery case 2 and the first battery case 1. The supporting device 31 supports the second battery case 2 to maintain a fixed interval from the first battery case 1 without affecting the cooling liquid 3. Circulation. The one-way relief valve 23 is disposed on the second battery case 2, and is directly in communication with the outside, instead of being in communication with the first battery case 1.

Example 5

The second battery case 2 is provided with a sealing liquid 24 and a battery module 21, and the battery module 21 is placed upside down in the second battery case 2, and the tabs of the battery module 21 are immersed in the sealing liquid 24, and the blocking liquid 24 is a fluorohydrocarbon.

In addition, a cooling liquid 3 is further disposed between the second battery case 2 and the first battery case 1, and the cooling liquid 3 is water, that is, the second battery case 2 is immersed in the cooling liquid 3, and the temperature control is set on the second battery case 2 At point 22, the temperature control break point 22 forms a hole at a temperature above 80 ° C, so that the coolant 3 can enter the second battery case 2.

A supporting device 31 is disposed between the second battery case 2 and the first battery case 1. The supporting device 31 supports the second battery case 2 to maintain a fixed interval from the first battery case 1 without affecting the cooling liquid. 3 circulation. The one-way relief valve 23 is disposed on the second battery case 2, and is directly in communication with the outside, instead of being in communication with the first battery case 1.

Example 6

As shown in FIG. 4, the present invention discloses a battery pack including a first battery case 1, the first battery case 1 including a case cover 11, and the first battery case 1 is sealed with respect to the outside. A second battery case 2 is disposed in the first battery case 1, the first battery case 1 and the second battery case 2 share a case cover 11, and the second battery case 2 is sealed with respect to the first battery case 1.

In addition, a cooling liquid 3 is further disposed between the second battery case 2 and the first battery case 1, the cooling liquid 3 is an aqueous solution of ethylene glycol, the second battery case 2 is immersed in the cooling liquid 3, and the second battery case 2 is partially wall-mounted. Melting temperature In the high molecular polymer between 90 ° C and 120 ° C, when an abnormality causes an increase in temperature and reaches a melting temperature of a part of the wall of the second battery case 2, part of the wall of the second battery case 2 is quickly broken, so that The coolant 3 enters the second battery case 2.

Claims

A battery pack includes a first battery case, the first battery case is sealed from the outside, and is characterized in that: a second battery case is disposed in the first battery box, and the second battery box is opposite to the first battery a tank is sealed, a battery module and a sealing liquid are disposed in the second battery box, the battery module is at least partially immersed in the sealing liquid, and a cooling liquid is disposed between the second battery box and the first battery box, and the cooling liquid is The latent heat of vaporization is higher than the heat capacity of the blocking liquid or the latent heat of vaporization.
The battery pack according to claim 1, wherein a temperature control break point is disposed on the second battery case, and the temperature control break point forms a hole when the temperature reaches a preset temperature or more, so that the coolant enters the first Two battery boxes.
The battery pack according to claim 2, wherein said temperature control break point is a low melting point alloy or a low melting point polymer, and said low melting point alloy or low melting point polymer has a melting point of between 70 and 200 °C.
The battery pack according to claim 3, wherein said low melting point alloy or low melting point polymer has a melting point of between 70 and 150 ° C; more preferably said low melting point alloy or low melting point polymer has a melting point of 70 Between ~130 °C.
The battery pack according to claim 3, wherein the low melting point alloy is at least one selected from the group consisting of Ga, In, Sn, Bi, Pb, Cd, and Zn.
The battery pack according to claim 3, wherein said low melting point polymer is selected from the group consisting of copolymers of ethylene and butene, copolymers of ethylene and acetic acid, acrylonitrile-butadiene-styrene copolymer, and poly At least one of a urethane, a nylon, and a chlorinated polyvinyl chloride.
The battery pack according to claim 2, wherein said preset temperature is between 70 and 150 °C.
The battery pack according to claim 7, wherein said preset temperature is between 80 and 130 °C.
The battery pack according to claim 2, wherein the liquid level of the cooling liquid is higher than the liquid level of the blocking liquid.
The battery pack according to claim 2, wherein the hydraulic pressure of the coolant is higher than the hydraulic pressure of the seal liquid.
The battery pack according to claim 1, wherein said blocking liquid comprises an insulating flame-retardant liquid having a freezing point lower than -30 ° C and a decomposition temperature higher than 70 ° C.
The battery pack according to claim 11, wherein said blocking liquid is at least one selected from the group consisting of silicone oil, transformer oil, chlorofluorocarbon, fluorohydrocarbon, chlorinated hydrocarbon, and hydrofluoroether.
The battery pack according to claim 1, wherein said coolant has a boiling point of between 70 and 150 °C.
The battery pack according to claim 1, wherein the cooling liquid is at least one selected from the group consisting of water and an aqueous solution.
The battery pack according to claim 14, wherein the aqueous solution is selected from the group consisting of aqueous solutions of alcohols.
The battery pack according to claim 15, wherein the alcohol is selected from the group consisting of ethylene glycol, ethylene glycol, propylene glycol, 1,3-butylene glycol, hexanediol, diethylene glycol, and At least one of glycerol.
The battery pack according to claim 1, wherein said battery module is placed upside down in said second battery case such that said battery module is at least partially immersed in the blocking liquid.
The battery pack according to claim 1, wherein a support means is disposed between the second battery case and the first battery case.
The battery pack according to claim 1, wherein a pressure relief valve is disposed on said first battery case and/or said second battery case.