WO2017000293A1

WO2017000293A1 - Battery pack

Info

Publication number: WO2017000293A1
Application number: PCT/CN2015/083135
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: CN107615568B; CN107615568A

Abstract

The present invention provides a battery pack. The battery pack comprises a battery box and a battery module disposed in the battery box. The battery box is sealed relative to the outside. A confining liquid is arranged in the battery box. The battery module is at least partially immersed in the confining liquid. A water absorbent polymer A is added in the confining liquid. The liquid absorption rate in the water absorbent polymer A is higher than 10%. The technical solution provided in the present invention can effectively constrain the spread of thermal runaway of the battery pack.

Description

Battery

Technical field

A battery pack including a thermal 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

The invention provides a battery pack including a thermal control system, comprising a battery case and a battery module disposed in the battery case, the battery case is sealed with respect to the outside, and the battery case is provided with a sealing liquid, and the battery module is at least Partially immersed in a blocking liquid to which a water-absorbent polymer A is added, and the water-absorbing polymer A has a liquid absorption rate of 10% or more.

The sealing fluid seals the electrical components of the battery pack from the outside world and prevents air from damaging the electrical components. Under this premise, if the battery pack leaks, the leaked liquid flows into the blocking liquid and is closed by the sealing liquid to prevent the air from reacting with it.

Further, the water absorbing polymer A has a liquid absorption rate of 50% or more, and more preferably the water absorbing polymer A has a liquid absorption rate of 100% or more.

Preferably, the above blocking liquid is further added with a water-absorbing polymer B, the water-absorbing polymer B having a liquid absorption rate of less than 50%; preferably, the water-absorbing polymer B has a liquid absorption rate of less than 20%; more preferably, the Water absorption The liquid absorption rate of the polymer B was zero.

The water-absorbing polymer A and the water-absorbing polymer B in the blocking liquid are added in an amount of 5 to 200:1, more preferably pure water-absorbent polymer A and pure water-absorbent polymerization. The mass ratio of the substance B is 10 to 100:1; wherein the mass of the pure water-absorbent polymer A or the pure water-absorbent polymer B means the mass of the water-absorbing polymer A or the water-absorbent polymer B which does not absorb any liquid, that is, the pure polymer quality.

In the present invention, the liquid absorption rate means the mass percentage of the liquid absorbed by the water absorbing polymer and the water absorbing polymer before the liquid is absorbed, that is, the liquid absorption rate = W ₁ (liquid mass) / W ₂ (the mass of the water absorbing polymer before water absorption) ) × 100%. Wherein W ₁ (liquid mass) = W ₃ (mass of water-absorbent polymer after water absorption) - W ₂ (mass of water-absorbent polymer before water absorption).

According to one embodiment of the invention, the blocking liquid comprises an insulating flame retardant liquid having a freezing point below -30 ° C and a decomposition temperature above 60 ° C. According to another embodiment of the invention, the blocking liquid comprises an insulating flame retardant liquid having a freezing point below -30 ° C and a boiling point above 60 ° C.

The blocking liquid is a cooling liquid having insulating and flame retarding properties, and has a freezing point lower than -30 ° C, a boiling point higher than 60 ° C or a decomposition temperature. Generally, the normal operating temperature of the battery pack is not higher than 60 ° C, so the decomposition temperature of the blocking liquid should be higher than 60 ° C. The above insulating flame retardant 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.

The water-absorbent polymer A and/or the water-absorbent polymer B in the present invention are generally polymers having a hydrophilic group, capable of absorbing a large amount of water and swelling, and capable of retaining moisture. It is understood according to the object of the present invention that any polymer which is capable of absorbing water or an aqueous solution and which is insoluble or sparingly soluble in the blocking liquid can be used as the water-absorbent polymer of the present invention and achieve the technical effects of the present invention. According to an embodiment of the present invention, the water-absorbing polymer A and/or the water-absorbing polymer B may be independently selected from the group consisting of an acrylic polymer, an acrylamide polymer, a starch polymer, an acrylonitrile polymer, and cellulose. At least one of a polymer such as a polymer, a vinyl alcohol polymer, and a polyoxyethylene polymer.

Preferably, the above water-absorbing polymer A and/or water-absorbing polymer B may be independently selected from the group consisting of: crosslinked polyacrylate, polyacrylate, polyacrylate graft polymer, saponified vinyl acetate-acrylate copolymer, ethylene Alcohol-acrylate cross-linking copolymer, hydrolyzed acrylamide copolymer, grafted acrylamide polymer, Crosslinked hydroxyethyl cellulose grafted acrylamide polymer, starch-acrylic graft copolymer, starch grafted acrylate polymer, starch-acrylonitrile graft copolymer, hydrolyzed acrylonitrile copolymer, high degree of substitution Crosslinked carboxymethyl cellulose, croscarmellose grafted acrylamide, croscarmellose alkali metal salt, crosslinked polymer of polyvinyl alcohol grafted with maleic anhydride, Ethylene-maleic anhydride copolymer, isobutylene-maleic anhydride copolymer, poly(vinyl sulfonate), poly(vinyl phosphonate), poly(vinyl phosphate), poly(vinyl sulfate), Sulfonated polystyrene, polyvinylamine, polydialkylaminoalkyl (meth)acrylamide, polyethyleneimine, polyarylamine, polyarylsulfonium, polydimethyldiarylammonium hydroxide, At least one of a quaternized polystyrene derivative, fluorene-modified polystyrene, quaternized poly(meth)acrylamide, polyethylene hydrazine, and the like. According to the object of the present invention, the water-absorbent polymer A and the water-absorbent polymer B may be the same or different.

The water-absorbent polymer is generally a polymer electrolyte containing a hydrophilic group and a crosslinked structure. Before water absorption, the polymer chains are entangled with each other and crosslinked into a network structure to achieve overall fastening. Upon contact with water, water molecules penetrate into the resin by capillary action and diffusion, and the ionized groups on the chain are ionized in water. The polymer chain stretches and swells due to the electrostatic repulsion between the ions on the chain. Due to the electrical neutrality requirement, the counter ions cannot migrate to the outside of the resin, and the difference in ion concentration between the internal and external solutions of the resin forms a reverse osmotic pressure. The water further enters the resin under the action of reverse osmosis pressure to form a hydrogel.

The water-absorbing polymer can absorb water equivalent to several hundred to several thousand times its own weight, and has a fast water absorption rate and is not easily released after water absorption. Moreover, the liquid absorbed by the water absorbing resin is not limited to water, and has a strong absorption capacity for other types of liquids.

According to an embodiment of the present invention, the liquid absorbed in the water-absorbing polymer A and/or the water-absorbing polymer B is at least one selected from the group consisting of water and an aqueous solution. The aqueous solution is preferably a solution obtained by dissolving other high specific heat capacity substances in water.

Both the water and the aqueous solution obtained by dissolving other high specific heat capacity substances in water have a high specific heat capacity, and the boiling point of the water or the aqueous solution in the present invention is below the temperature at which the battery pack is thermally out of control, before the thermal runaway further spreads, or The aqueous solution undergoes a phase change, absorbs more heat, and more effectively controls the wide spread of thermal runaway in the battery pack.

According to an embodiment of the present invention, the liquid absorbed in the water-absorbing polymer A and/or the water-absorbing polymer B is water or an aqueous solution; the aqueous solution is selected from an aqueous solution of an alcohol; the alcohol may be selected from ethylene glycol, At least one of 1,2-ethylene glycol, propylene glycol, 1,3-butylene glycol, hexanediol, diethylene glycol, glycerin, and the like Kind. The aqueous solution of the above substances can effectively lower the freezing point and improve the working performance in a low temperature environment.

The water-absorbent polymer A and/or the water-absorbent polymer B are added to the blocking liquid, and the water-absorbent polymer A and the water-absorbent polymer B are both insoluble or slightly soluble in the blocking liquid and remain stable. The water absorption rate of the water-absorbent polymer A is 10% or more, and the liquid absorption rate in the water-absorbing polymer A is preferably 50% or more, and it is more preferable that the liquid absorption rate in the water-absorbent polymer A is 100% or more. When the local heat accumulation of the battery module, the temperature rises rapidly and local thermal runaway occurs, the blocking liquid is not enough to take away the rapidly generated heat, and the liquid (such as water or aqueous solution) in the water-absorbing polymer A will rapidly heat up and then undergo phase change absorption. A large amount of heat controls the temperature inside the battery pack to avoid further spread of thermal runaway.

After a long period of use, the blocking solution may contain a certain amount of moisture, which will reduce the insulation performance of the entire battery. The water-absorbent polymer B having a liquid absorption rate of less than 20% is disposed in the blocking liquid, which is advantageous for removing the water from the blocking liquid, so that the battery pack maintains good insulation performance.

According to the object of the present invention, when the water-absorbent polymer A (and the water-absorbent polymer B) is added to the blocking liquid, the amount of the water-absorbent polymer A should be larger than the amount of the water-absorbent polymer B in order to secure the effect of temperature control in the battery pack.

According to an embodiment of the present invention, the water-absorbing polymer A and/or the water-absorbing polymer B and the battery module are separated by a porous layer which makes the water-absorbent polymer A and/or the water-absorbent polymer B not In direct contact with the battery module, the liquid absorbed in the water-absorbent polymer A and/or the water-absorbent polymer B and the blocking liquid can pass freely through the porous layer.

The porous layer is selected from at least one of a nonwoven fabric, a porous film, a mesh, and the like. In a specific operation, the water-absorbent polymer A and/or the water-absorbent polymer B may be wrapped in a porous layer such as a nonwoven fabric, and then placed in a blocking liquid in a battery case.

Preferably, the battery module is placed upside down in the battery compartment such that the tabs of the battery module are submerged in the blocking fluid.

When the battery cells are placed upside down, the battery cells are placed with the ears down, so that the electrodes can be immersed in the blocking liquid even when less blocking liquid is used. For the battery unit, the heat generated by the ear is relatively large, and it is more favorable for heat dissipation by immersing it in the sealing liquid, and it is also advantageous for insulation of the battery module.

For flexible packaging batteries, the position of the tabs of the ear is relatively easy to break, and the active material inside the battery is easier to flow out from the break. Inverting the battery unit helps to reduce the exposure time of the leaking substances in the air. Once a leak occurs, it quickly flows into the blocking fluid, improving safety.

The technical solution disclosed by the invention can more effectively control the spread of thermal runaway of the battery module. When some cells in the battery module have problems, a large amount of heat is generated to cause the local temperature to rise rapidly, at this time, the water-absorbing polymer The liquid absorbed in A and/or water-absorbing polymer B can absorb a large amount of heat, and the liquid phase change can take away heat, thereby effectively controlling the rapid rise of temperature in the battery module, so that the temperature in the battery pack can be effectively controlled to prevent heat. The spread of loss of control minimizes losses.

DRAWINGS

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

2 is a schematic view showing the structure of a water-absorbing polymer A packaged in a porous layer according to the present invention;

3 is a schematic view showing the structure of a water-absorbing polymer B wrapped in a porous layer according to the present invention;

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

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

Figure 6 is a schematic view showing the structure of a water-absorbing polymer A and a water-absorbing polymer B in the porous layer disclosed in the present invention;

Among them, 1. battery box, 11. porous layer, 12. water-absorbing polymer A, 13. water-absorbing polymer B, 14. sealing liquid, 2. battery module.

detailed description

Example 1

As shown in FIG. 1 , FIG. 2 and FIG. 3 , the present invention discloses a battery pack including a battery case 1 and a battery module 2 . The battery case 1 is sealed with respect to the outside, and the battery case 1 is further provided with a sealing liquid 14 and a battery module 2 . Inverted and disposed in the battery case 1 such that the tabs of the battery module 2 are immersed in the sealing liquid 14, and the electrical components in the battery module 2 and the battery box 1 are immersed in the sealing liquid 14, in particular, the ear portion in the battery module 2. And the current collecting portion, the porous layer 11 is further provided in the blocking liquid 14, the water absorbing polymer A12 and the water absorbing polymer B13, the water absorbing polymer A12 and the water absorbing polymer B13 are insoluble in the sealing liquid 14, and the liquid absorbing rate of the water absorbing polymer A12 is More than 20%, the water absorption rate of the water-absorbent polymer B13 is 20% or less.

The water-absorbent polymer A12 is disposed in the porous layer 11, and the water-absorbent polymer B13 is disposed in the other porous layer 11 not containing the water-absorbent polymer A12, and the porous layer 11 allows the blocking liquid 14 to pass through and into the porous layer 11, also The water-absorbent polymer A12 and the water-absorbent polymer B13 cannot pass through, thereby restricting the positions of the water-absorbent polymer A12 and the water-absorbent polymer B13 from being directly in contact with the charged portion/electrical component of the battery cell, and the porous layer 11 is selected to be non-woven. cloth.

After a long period of use, the sealing liquid 14 may inhale a certain amount of water, which may reduce the insulation performance of the entire battery pack, and a water absorbing polymer B13 having a liquid absorption rate of 20% or less is disposed in the sealing liquid 14 It is beneficial to dehumidify the sealing liquid 14 and maintain good insulation performance. When the thermal runaway occurs locally in the battery module 2, the moisture phase in the water absorbing polymer A12 and the water absorbing polymer B13 becomes water vapor, and heat is quickly absorbed to prevent the spread of thermal runaway.

Further, in the present embodiment, the mass ratio of the pure water-absorbent polymer A12 to the pure water-absorbent polymer B13 was 8.

The liquid in the water-absorbent polymer A12 and the water-absorbent polymer B13 is an aqueous solution of ethylene glycol, the water-absorbent polymer A12, and the water-absorbent polymer B13 are cross-linked polyacrylates, and silicone oil is used as the blocking liquid 14.

Example 2

As shown in FIG. 1 , FIG. 2 and FIG. 3 , the present invention discloses a battery pack including a battery case 1 and a battery module 2 . The battery case 1 is sealed with respect to the outside, and the battery case 1 is further provided with a sealing liquid 14 and a battery module 2 . Inverted and disposed in the battery case 1 such that the tabs of the battery module 2 are immersed in the sealing liquid 14, and the electrical components in the battery module 2 and the battery box 1 are immersed in the sealing liquid 14, in particular, the ear portion in the battery module 2. And the current collecting portion, the porous layer 11, the water absorbing polymer A12 and the water absorbing polymer B13 are further disposed in the blocking liquid 14, the water absorbing polymer A12 and the water absorbing polymer B13 are insoluble in the blocking liquid 14, and the liquid absorbing rate of the water absorbing polymer A12 is More than 50%, the water absorption rate of the water-absorbent polymer B13 is 20% or less.

After a long period of use, the blocking solution 14 may inhale a certain amount of water, which may reduce the insulation performance of the entire battery pack, and the water-absorbent polymer B13 having a liquid absorption rate of 20% or less is disposed in the sealing liquid 14, which is advantageous for The sealing liquid 14 is dehumidified to maintain good insulation properties. When the thermal runaway occurs locally in the battery module 2, the water phase in the water absorbing polymer A12 and the water absorbing polymer B13 becomes water vapor, and heat is quickly absorbed to prevent the spread of thermal runaway.

Further, in the present embodiment, the mass ratio of the pure water-absorbent polymer A12 to the pure water-absorbent polymer B13 was 20.

The liquid in the water-absorbent polymer A12 and the water-absorbent polymer B13 is an aqueous solution of ethylene glycol, the water-absorbent polymer A12, and the water-absorbent polymer B13 are vinyl alcohol-acrylate cross-linked copolymers, and silicone oil is used as the sealing liquid 14 .

Example 3

As shown in FIG. 1 , FIG. 2 and FIG. 3 , the present invention discloses a battery pack including a battery case 1 and a battery module 2 . The battery case 1 is sealed with respect to the outside, and the battery case 1 is further provided with a sealing liquid 14 and a battery module 2 . Inverted and disposed in the battery case 1 such that the tabs of the battery module 2 are immersed in the sealing liquid 14, and the electrical components in the battery module 2 and the battery box 1 are immersed in the sealing liquid 14, in particular, the ear portion in the battery module 2. And the current collecting portion, the sealing liquid 14 is further provided with a porous layer 11, a water absorbing polymer A12 and a water absorbing polymer B13, and the water absorbing polymer A12 and the water absorbing polymer B13 are insoluble in the sealing liquid 14, and the liquid absorbing rate of the water absorbing polymer A12 is More than 80%, the water absorption rate of the water-absorbent polymer B13 is 10% or less.

After a long period of use, the blocking solution 14 may inhale a certain amount of water, which may reduce the insulation performance of the entire battery pack, and the water-absorbent polymer B13 having a liquid absorption rate of 10% or less is disposed in the sealing liquid 14, which is advantageous for The sealing liquid 14 is dehumidified to maintain good insulation properties. When the thermal runaway occurs locally in the battery module 2, the water phase in the water absorbing polymer A12 and the water absorbing polymer B13 becomes water vapor, and heat is quickly absorbed to prevent the spread of thermal runaway.

Further, in the present embodiment, the mass ratio of the pure water-absorbent polymer A12 to the pure water-absorbent polymer B13 was 10.

The liquid in the water-absorbent polymer A12 and the water-absorbent polymer B13 is water, the water-absorbent polymer A12, and the water-absorbent polymer B13 are vinyl alcohol-acrylate cross-linked copolymers, and silicone oil is used as the sealing liquid 14.

Example 4

As shown in FIG. 4, the present invention discloses a battery pack including a battery case 1 and a battery module 2, the battery case 1 is sealed with respect to the outside, and a sealing liquid 14 is further disposed in the battery case 1, and the battery module 2 is disposed upside down in the battery case 1 Therefore, the tabs of the battery module 2 are immersed in the sealing liquid 14, and the electrical components in the battery module 2 and the battery box 1 are immersed in the sealing liquid 14, in particular, the ear portion and the collecting portion of the battery module 2, and are closed. The water absorbing polymer A12 and the water absorbing polymer B13 are further disposed in the liquid 14, the water absorbing polymer A12 and the water absorbing polymer B13 are insoluble in the blocking liquid 14, the liquid absorbing rate of the water absorbing polymer A12 is 80% or more, and the water absorbing polymer B13 is sucked. The liquid rate is below 10%.

After a long period of use, the blocking solution 14 may inhale a certain amount of water, which will reduce the entire The insulating property of the battery pack is such that the water absorbing polymer B13 having a liquid absorption rate of 10% or less is disposed in the sealing liquid 14, which is advantageous for dehumidifying the sealing liquid 14 and maintaining good insulation performance. When the thermal runaway occurs locally in the battery module 2, the water phase in the water absorbing polymer A12 and the water absorbing polymer B13 becomes water vapor, and heat is quickly absorbed to prevent the spread of thermal runaway.

The liquid in the water-absorbent polymer A12 and the water-absorbent polymer B13 is an aqueous solution of propylene glycol, the water-absorbent polymer A12, and the water-absorbent polymer B13 are vinyl alcohol-acrylate cross-linked copolymers, and silicone oil is used as the sealing liquid 14.

Example 5

As shown in FIG. 5, the present invention discloses a battery pack including a battery case 1 and a battery module 2, the battery case 1 is sealed with respect to the outside, and a sealing liquid 14 is further disposed in the battery case 1, and the battery module 2 is disposed upside down in the battery case 1. Therefore, the tabs of the battery module 2 are immersed in the sealing liquid 14, and the electrical components in the battery module 2 and the battery box 1 are immersed in the sealing liquid 14, in particular, the ear portion and the collecting portion of the battery module 2, and are closed. A water-absorbent polymer A12 is further provided in the liquid 14, and the water-absorbent polymer A12 is insoluble in the blocking liquid 14, and the liquid-absorbent ratio of the water-absorbent polymer A12 is 80% or more.

When the thermal runaway occurs locally in the battery module 2, the water phase in the water-absorbent polymer A12 becomes water vapor, rapidly absorbing heat, and avoiding the spread of thermal runaway.

The liquid in the water-absorbent polymer A12 is an aqueous solution of propylene glycol, the water-absorbent polymer A12 is a vinyl alcohol-acrylate cross-linked copolymer, and a silicone oil is used as the blocking liquid 14.

Example 6

As shown in FIG. 1 and FIG. 6 , the present invention discloses a battery pack including a battery case 1 and a battery module 2. The battery case 1 is sealed with respect to the outside, and a sealing liquid 14 is further disposed in the battery case 1. The battery module 2 is disposed upside down. In the battery case 1, the tabs of the battery module 2 are immersed in the sealing liquid 14, and the electrical components in the battery module 2 and the battery box 1 are immersed in the sealing liquid 14, in particular, the ear portion and the current collecting in the battery module 2. In the portion, the sealing liquid 14 is further provided with a porous layer 11, a water-absorbent polymer A12 and a water-absorbent polymer B13, and the water-absorbent polymer A12 and the water-absorbent polymer B13 are insoluble in the blocking liquid 14, and the liquid-absorbent ratio of the water-absorbing polymer A12 is 20% or more. The water absorption rate of the water-absorbent polymer B13 is 20% or less.

The water-absorbent polymer A12 and the water-absorbent polymer B13 are disposed in the same porous layer, and the porous layer 11 allows the blocking liquid 14 to pass through and into the porous layer 11, and also allows the water-absorbent polymer A12 and the water-absorbent polymer B13 to pass through, thereby restricting The position of the water-absorbent polymer A12 and the water-absorbent polymer B13 is not allowed to be with the battery bill The charged portion/electrical component of the body is in direct contact, and the porous layer 11 is made of a nonwoven fabric.

After a long period of use, the blocking solution 14 may inhale a certain amount of water, which may reduce the insulation performance of the entire battery pack, and the water-absorbent polymer B13 having a liquid absorption rate of 20% or less is disposed in the sealing liquid 14, which is advantageous for The sealing liquid 14 is dehumidified to maintain good insulation properties. When the thermal runaway occurs locally in the battery module 2, the moisture phase in the water absorbing polymer A12 and the water absorbing polymer B13 becomes water vapor, and heat is quickly absorbed to prevent the spread of thermal runaway.

Further, in the present embodiment, the mass ratio of the pure water-absorbent polymer A12 to the pure water-absorbent polymer B13 was 8. The liquid in the water-absorbent polymer A12 and the water-absorbent polymer B13 is an aqueous solution of ethylene glycol, the water-absorbent polymer A12, and the water-absorbent polymer B13 are cross-linked polyacrylates, and silicone oil is used as the blocking liquid 14.

Claims

A battery pack comprising a battery case and a battery module disposed in the battery case, the battery case being sealed from the outside, wherein the battery case is provided with a sealing liquid, and the battery module is at least partially immersed in the sealing liquid The water-absorbent polymer A is added to the blocking liquid, and the water-absorbing polymer A has a liquid absorption rate of 10% or more.
The battery pack according to claim 1, wherein the water absorbing polymer A has a liquid absorption rate of 50% or more, and more preferably the water absorbing polymer A has a liquid absorption rate of 100% or more.
The battery pack according to claim 1, wherein a water absorbing polymer B is further added to the blocking liquid, and a liquid absorption rate in the water absorbing polymer B is less than 50%, more preferably the water absorbing polymer B The liquid absorption rate is less than 20%.
The battery pack according to claim 3, wherein the amount of the water-absorbing polymer A and the water-absorbing polymer B in the blocking liquid is such that the mass ratio of the pure water-absorbent polymer A to the pure water-absorbent polymer B is 5 to 200. :1.
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 60 ° C.
The battery pack according to claim 5, wherein the insulating flame retardant 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 any one of claims 1 to 6, wherein the water-absorbing polymer A and/or the water-absorbing polymer B are selected from the group consisting of acrylic polymers, acrylamide polymers, starch polymers, and propylene. At least one of a nitrile polymer, a cellulose polymer, a vinyl alcohol polymer, and a polyoxyethylene polymer.
The battery pack according to any one of claims 1 to 6, wherein the water-absorbing polymer A and/or the water-absorbing polymer B are selected from the group consisting of crosslinked polyacrylate, polyacrylate, and polyacrylate graft polymer. , saponified vinyl acetate-acrylate copolymer, vinyl alcohol-acrylate crosslinked copolymer, hydrolyzed acrylamide copolymer, grafted acrylamide polymer, crosslinked hydroxyethyl cellulose grafted acrylamide polymer, starch -Acrylic graft copolymer, starch grafted acrylate polymer, starch-acrylonitrile graft copolymer, hydrolyzed acrylonitrile copolymer, high degree of substitution crosslinked carboxymethyl cellulose, crosslinked carboxymethyl cellulose Acrylamide, croscarmellose alkali metal salt, crosslinked polymer of polyvinyl alcohol grafted with maleic anhydride, ethylene-maleic anhydride copolymer, isobutylene-maleic anhydride copolymer, Poly(vinyl sulfonate), poly(vinyl phosphonate), poly(vinyl phosphate), poly(vinyl sulfate), sulfonated polystyrene, polyvinylamine, Polydialkylaminoalkyl (meth)acrylamide, polyethyleneimine, polyarylamine, polyarylsulfonium, polydimethyldiarylammonium hydroxide, quaternized polystyrene derivative, hydrazine At least one of modified polystyrene, quaternized poly(meth)acrylamide, polyethylene hydrazine, and the like.
The battery pack according to any one of claims 1 to 6, wherein the liquid absorbed in the water-absorbent polymer A and/or the water-absorbent polymer B is at least one selected from the group consisting of water and an aqueous solution.
The battery pack according to claim 9, wherein the aqueous solution is selected from the group consisting of aqueous solutions of alcohols.
The battery pack according to claim 10, wherein the alcohol is selected from the group consisting of aqueous glycol solution, ethylene glycol, propylene glycol, 1,3-butylene glycol, hexanediol, and diethylene glycol. At least one of an alcohol and glycerol.
The battery pack according to any one of claims 1 to 6, wherein the water absorbing polymer A and/or the water absorbing polymer B and the battery module are separated by a porous layer, the porous layer making the water absorbing polymer The A and/or water-absorbing polymer B is not in direct contact with the battery module, and the liquid absorbed in the water-absorbent polymer A and/or the water-absorbent polymer B and the blocking liquid can pass freely.
The battery pack according to claim 12, wherein the porous layer is at least one selected from the group consisting of a nonwoven fabric, a porous film, and a mesh.
The battery pack according to claim 1, wherein said battery module is placed upside down in the battery case such that the tabs of said battery module are immersed in the sealing liquid.