Lithium ion battery with self-destruction device

Abstract

The utility model provides a lithium ion battery with a self-destruction device, and belongs to the technical field of new energy batteries. The self-destruction device comprises a sealing cavity made of a polymer material and a hydrate which is arranged in the sealing cavity and contains crystal water, and the sealing cavity is arranged in a redundant space of lower plastic of the top cover of the lithium ion battery. According to the utility model, the self-destruction device is arranged below the lower plastic, so that the redundancy of the space is utilized, the effective volume of the battery cell is not occupied, the volume energy density of the battery cell is not influenced, and the situation that the self-destruction device is placed on two sides of the thickness direction of the battery cell, occupies the thickness space of the pole piece and reduces the space utilization rate is avoided; and meanwhile, the possibility of leakage of the hydrate self-destruction agent caused by extrusion of the self-destruction device due to volume expansion in the thickness direction of the battery after the battery is charged or circulated for a certain number of times in actual use is avoided. The lithium ion battery provided by the utility model can block the thermal runaway of the battery on the surface of the battery core, avoids the fire and explosion of the battery, and solves the problem that the thermal runaway of the battery is not completely blocked.

Description

TECHNICAL FIELD

[0001] The utility model belongs to new energy battery technical field, concretely relates to a lithium ion battery containing self-destruction device. BACKGROUND

[0002] With the increasing of the number of electric vehicles, the number of safety accidents is also increasing, and the safety of power battery has become an important performance concerned by all practitioners. The existing safety design scheme realizes the heat non-propagation by blocking the heat transfer at the pack design level, and more focuses on improving the thermal stability of the battery itself or reducing the heat production of the battery thermal runaway at the cell design level. The existing cell safety design scheme mostly improves the thermal stability of the battery itself or reduces the heat production of the battery thermal runaway by adding flame retardant in the electrolyte, reducing the proportion of ethylene carbonate (EC) to reduce the reaction heat, introducing ceramic diaphragm to improve the thermal stability of the diaphragm, but it cannot completely block the thermal runaway of the battery, and can only improve the occurrence time and heat production of the thermal runaway. How to block the thermal runaway of the battery at the cell level and avoid the fire and explosion of the battery is a more direct and effective key technology for battery safety research. UTILITY MODEL CONTENT

[0003] In view of the deficiencies and defects existing in the prior art, the utility model aims at providing a lithium ion battery containing self-destruction device to block the thermal runaway of the battery at the cell level, avoid the fire and explosion of the battery, and solve the problem of incomplete blocking of battery thermal runaway.

[0004] To achieve the above-mentioned purpose, the utility model adopts the following technical scheme:

[0005] A lithium ion battery containing self-destruction device, the self-destruction device includes a sealed cavity of high molecular material and a hydrate containing crystal water arranged in the sealed cavity, the sealed cavity is arranged in the redundant space of the lower plastic of the top cover of the lithium ion battery, and the self-destruction device is self-destructed when the lithium ion battery is heated to a preset temperature, that is, the hydrate containing crystal water is decomposed and dehydrated to cause the deformation and rupture of the sealed cavity under heat.

[0006] Further, the reinforcement rib on the lower plastic avoids the installation space of the sealed cavity.

[0007] Further, the upper surface of the sealed cavity is matched with the lower surface of the lower plastic to form an assembly structure, and the sealed cavity is fixed in the lower plastic through the structure assembly;

[0008] And / or, the sealed cavity is fixed in the lower plastic by adhesion.

[0009] Further, the lithium ion battery is a square battery.

[0010] And / or, the thickness direction of the pole piece of the lithium ion battery is perpendicular to the thickness direction of the self-destruction device.

[0011] And / or, the pole piece of the lithium ion battery is any one of a laminated piece or a wound structure.

[0012] Further, the dehydration temperature of the hydrate containing crystal water is 60-300 DEG C.

[0013] Further, the hydrate containing crystal water has a crystal water content of 45-55%.

[0014] Further, the hydrate containing crystal water includes FeSO4.7H2O or MgSO4.7H2O.

[0015] Further, the wall thickness of the sealed cavity is 0.1-0.5 mm; and / or, the sealed cavity is prepared by an integral injection molding method, a lower surface is reserved for filling, and the filling port is used to fill the hydrate containing crystal water.

[0016] Further, the upper limit of the temperature resistance of the sealed cavity is 130-170 DEG C.

[0017] Further, the material of the sealed cavity includes PC and PP.

[0018] Compared with the prior art, the utility model has the following effective effects:

[0019] The utility model discloses a self-destruction device of polymer coated hydrate is arranged below the lower plastic of lithium ion battery top cover, especially utilizes the redundancy of this part of space (the lower surface of lower plastic is because of structure and safety design, and there is redundant space between electric core such as roll core, and the self-destruction device shell insulation will not reduce safety redundancy design), does not occupy the effective volume of electric core, will not produce the influence to the volume energy density of electric core, avoids being placed in the thickness direction of electric core two sides, occupies the thickness space, reduces space utilization rate, and simultaneously avoids when actually using, the battery is charged or after circulating a certain number of times, the thickness direction of battery will have volume expansion extrusion self-destruction device, leads to the possibility of hydrate self-destruction agent leakage.

[0020] The utility model discloses a self-destruction device in battery internal temperature reaches 100-165 DEG C, and the hydrate in sealed cavity interior decomposes and releases water and forms high pressure water vapor under high temperature, and the structure strength of cavity itself drops under the influence of temperature and breaks down under the interior water vapor pressure, and water vapor releases quickly and reacts with lithium salt in electrode and electrolyte and consumes active lithium, reaches the purpose of interrupting heat run-away heat production reaction, solves the problem of incomplete battery heat run-away block.

[0021] The utility model discloses a battery internal heat production self -triggering, and after triggering, the quick consumption of heat reaction substance, interrupt the heat runaway heat reaction, avoid the battery to appear the situation of fire explosion, simultaneously, can reduce the peak temperature of battery reaction heat production greatly, avoid the heat runaway diffusion. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the specific embodiment of the utility model or the technical scheme in prior art, the following will briefly introduce the drawing needed to be used in the specific embodiment or prior art description, obviously, the drawing in the following description is some implementation of the utility model, and for the ordinary skilled person in the art, other drawings can also be obtained according to these drawings without creative labor.

[0023] Figure 1 It is a lithium ion battery structure schematic diagram containing self-destruction device of the utility model,

[0024] Wherein, 1-sealing cavity, 2-the lower plastic, 3-the electric core. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical scheme and advantage of the utility model more clear, the following will be further explained by combining with the embodiment of the utility model.The embodiment of the utility model is implemented in the premise of the technical scheme of the utility model, and gives the detailed implementation mode and process, and the person skilled in the art should understand that the embodiment is only to help understanding the utility model, and should not be regarded as the specific limitation of the utility model, and the protection scope of the utility model is not limited to the following embodiment, and all other embodiments obtained by the person skilled in the art based on the embodiment in the utility model without creative labor are within the protection scope of the utility model.

[0026] In the description of the utility model, the orientation or positional relationship indicated by the terms such as '' opposite direction '' vertical '' upper '' lower '' parallel '' is based on the orientation or positional relationship shown in the drawing, and is only for the convenience of describing the utility model and does not require the utility model to be constructed and operated in a specific orientation, therefore, it cannot be understood as the limitation of the utility model.The terms '' connected '' connected '' set '' used in the utility model should be understood broadly, for example, it can be fixed connection, and can also be detachable connection;It can be directly connected, and also can be indirectly connected through an intermediate part;It can be wired electrical connection, wireless electrical connection, or wireless communication signal connection, and for the ordinary skilled person in the art, the specific meaning of the above terms can be understood according to the specific situation.

[0027] Unless otherwise specified and / or indicated, all numerical values of a component amount, as used herein, are to be understood as modified by the word "about". Unless otherwise specified and / or indicated, all components used in the examples herein are commercially available from commercial sources.

[0028] The endpoints of the ranges of the scope disclosed herein and any values expressed as ranges between such endpoints are not to be construed as to unqualifiedly limit the precise range or value to which they are expressed. Unless otherwise stated, the ranges of values should be interpreted as including the values approximately within the range. For numerical ranges expressed as "from X to Y," "X to Y," or "X-Y," any number falling within the range, as well as the values ending the range, can be combined with any other number or value within the same range to achieve a new range having a value within the range. For numerical ranges expressed as "from X to Y," "X to Y," or "X-Y," each intervening value of the range is also expressly included within the range. For the same reason, all statements of a value range are meant only to be used to indicate that a range of values is meant to be encompassed.

[0029] The utility model provides a kind of lithium ion battery containing self-destruction device, the self-destruction device includes the sealed cavity 1 of high molecular material and the hydrate containing crystal water in the sealed cavity 1, the sealed cavity 1 is located in the redundancy space of the lower plastic 2 of the lithium ion battery top cover, after the lithium ion battery is heated to preset temperature, the self-destruction device occurs self-destruction, i.e. hydrate containing crystal water decomposes dehydration and causes sealed cavity 1 to be heated while deforming rupture.

[0030] The utility model discloses a kind of self-destruction device of polymer-coated hydrate, which is arranged below the lower plastic 2 of the lithium ion battery top cover, especially utilizes the redundancy of this part of space (the lower surface of lower plastic 2 is due to structure and safety design, and there is redundancy space between electric core 3 such as roll core, self-destruction device shell insulation will not reduce safety redundancy design), without occupying the effective volume of electric core 3, without affecting the volume energy density of electric core 3, avoid being placed in the thickness direction of electric core 3, occupying thickness space, reducing space utilization rate;At the same time, avoid the possibility that hydrate self-destruction agent leaks when battery is charged or after a certain number of cycles in actual use, battery thickness direction has volume expansion extrusion self-destruction device.

[0031] The utility model discloses a kind of self-destruction device, when the temperature inside battery reaches 100~165 ℃, hydrate in sealed cavity 1 decomposes and releases water and forms high-pressure water vapor under high temperature, the structure strength of cavity itself is reduced under temperature influence and breaks under internal water vapor pressure, the water vapor released quickly reacts with lithium salt in electrode and electrolyte and consumes active lithium, to achieve the purpose of interrupting heat runaway heat production reaction, solve the problem of incomplete battery heat runaway blocking.

[0032] The utility model discloses a kind of self-destruction device, which is arranged below the lower plastic 2 of the lithium ion battery top cover, especially utilizes the redundancy of this part of space (the lower surface of lower plastic 2 is due to structure and safety design, and there is redundancy space between electric core 3 such as roll core, self-destruction device shell insulation will not reduce safety redundancy design), without occupying the effective volume of electric core 3, without affecting the volume energy density of electric core 3, avoid being placed in the thickness direction of electric core 3, occupying thickness space, reducing space utilization rate;At the same time, avoid the possibility that hydrate self-destruction agent leaks when battery is charged or after a certain number of cycles in actual use, battery thickness direction has volume expansion extrusion self-destruction device.

[0033] In the utility model, the lower plastic 2 is a general design in square aluminum shell lithium ion battery, and its role is the insulation structure between the cell and the top cover aluminum metal; usually, the reinforcing rib modeling is used to further strengthen the structural strength and assembly requirement, such as the grid structure formed by the reinforcing rib on the lower surface of the lower plastic 2. Therefore, as an optional implementation mode of the lithium ion battery of the utility model, the reinforcing rib avoidance position on the lower plastic 2 is the mounting space of the sealed cavity 1.

[0034] As an optional implementation mode of the lithium ion battery of the utility model, the upper surface modeling of the sealed cavity 1 is matched with the lower surface modeling of the lower plastic 2 to form an assembly structure, and the sealed cavity 1 is fixed in the lower plastic 2 through structural assembly;

[0035] And / or, the sealed cavity 1 is fixed in the lower plastic 2 through adhesive bonding.

[0036] As an optional implementation mode of the lithium ion battery of the utility model, the lithium ion battery is a square battery;

[0037] And / or, the thickness direction of the pole piece of the lithium ion battery is perpendicular to the thickness direction of the self-destruction device;

[0038] And / or, the pole piece of the lithium ion battery is any one of laminated structure or winding structure.

[0039] As an optional implementation mode of the lithium ion battery of the utility model, the dehydration temperature of the hydrate containing crystal water is 60-300 DEG C (such as 70 DEG C, 90 DEG C, 110 DEG C, 130 DEG C, 150 DEG C, 170 DEG C, 190 DEG C, 210 DEG C, 230 DEG C, 250 DEG C, 270 DEG C, 290 DEG C), when the temperature of the lithium ion battery rises to the dehydration temperature, the hydrate decomposes and dehydrates, which causes the sealed cavity 1 to deform and break at the same time, and the water is released and reacts with lithium salt, consumes active lithium, and at the same time reduces the reaction temperature, and blocks the thermal runaway reaction.

[0040] As an optional implementation mode of the lithium ion battery of the utility model, the hydrate containing crystal water has a crystal water content of 45-55% (such as 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%).

[0041] As an optional implementation mode of the lithium ion battery of the utility model, the hydrate containing crystal water includes FeSO4·7H2O or MgSO4·7H2O.

[0042] As an optional implementation of the lithium ion battery of the utility model, the wall thickness of the sealed cavity 1 is 0.1-0.5mm (such as 0.15mm, 0.2mm, 0.25mm, 0.3mm, 0.35mm, 0.4mm, 0.45mm); and / or, the sealed cavity 1 is prepared by using an integral injection molding mode, a lower surface is reserved with a filling port, and the filling port is used for loading the hydrate containing crystal water.

[0043] As an optional implementation of the lithium ion battery of the utility model, the upper limit of the temperature resistance of the sealed cavity 1 is 130-170 DEG C (such as 135 DEG C, 140 DEG C, 145 DEG C, 150 DEG C, 155 DEG C, 160 DEG C, 165 DEG C).

[0044] As an optional implementation of the lithium ion battery of the utility model, the material of the sealed cavity 1 includes polycarbonate (PC) and polypropylene (PP).

[0045] The heat runaway control principle of the lithium ion battery of the utility model is described in detail as follows:

[0046] (1) the self-destruction device blocks the early heat generation reaction of heat runaway by introducing hydrate containing crystal water, and consumes active lithium; wherein the hydrate includes FeSO4·7H2O (crystal water content 45.3%) and MgSO4·7H2O (crystal water content 51.2%). When the battery temperature rises to the dehydration temperature, the aforementioned crystal hydrate decomposes, releases water and reacts with lithium salt to consume active lithium, and at the same time, reduces the reaction temperature and prevents the temperature from further accumulating. The dehydration temperature of FeSO4·7H2O is 78 DEG C-159 DEG C, and the dehydration temperature of MgSO4·7H2O is 60 DEG C-285 DEG C. When the internal temperature of the battery reaches the dehydration temperature of the hydrate, water is decomposed and reacts with lithium salt to consume active lithium, avoid the occurrence of severe heat generation reaction, and interrupt the heat runaway process.

[0047] (2) the hydrate containing crystal water will react with the electrolyte at the normal working temperature of the battery, which has a negative impact on the normal electrical performance of the battery. In order to prevent the reaction from occurring, the hydrate is sealed in the shell (sealed cavity 1) composed of high molecular materials which do not react with the electrolyte, so as to block the direct contact of the hydrate with the electrolyte. The material of the sealed cavity 1 is PC, PP and the like, and the thickness of the material of the sealed cavity 1 is 0.1-0.5mm; the upper limit of the temperature resistance is 165 DEG C and 135 DEG C respectively, and when the temperature reaches the upper limit of the temperature resistance of the material, the hardness and strength decrease. At the same time, the pressure in the sealed cavity 1 increases due to the release of water by the hydrate in the sealed cavity 1, so that the sealed cavity 1 deforms and breaks, releases water, reacts with lithium salt, and blocks the heat runaway reaction.

[0048] (3) The arrangement position of the sealing cavity 1 is in the plastic 2 under the square battery top cover; the reinforcing rib of the plastic 2 avoids the installation space of the sealing cavity 1; the upper surface of the sealing cavity 1 is matched with the lower surface of the plastic 2 to form an assembly structure, and the sealing cavity 1 and the plastic 2 are fixed through structural assembly and an adhesive such as glue.

[0049] The utility model will be described in further detail in connection with specific embodiments.

[0050] Embodiment 1

[0051] A lithium ion battery containing a self-destruction device, the self-destruction device includes a sealing cavity 1 of polymer material and a hydrate containing crystal water arranged in the sealing cavity 1, and the sealing cavity 1 is arranged in the redundant space of the plastic 2 under the top cover of the lithium ion battery. Specifically, according to the lower surface modeling of the plastic 2, the upper surface modeling of the sealing cavity 1 is designed to form an assembly structure of the sealing cavity 1 and the plastic 2, and further through the glue, the sealing cavity 1 is completely fixed in the plastic 2 and located above the electrode core 3 of the laminated or wound structure, without occupying the volume space of the electrode core 3; the sealing cavity 1 is prepared by integral injection molding, and the lower surface is reserved for filling; the material of the sealing cavity 1 is PP material, and the temperature resistance is 135 DEG C; the thickness of the sealing material is 0.5 mm;

[0052] The hydrate filled in the sealing cavity 1 is magnesium sulfate heptahydrate (MgSO 4· 4·7H2O), which loses the first water molecule to become magnesium sulfate hexahydrate (MgSO4·6H2O) when the internal temperature of the battery rises to 60 DEG C. With the continuous rise of the temperature, the magnesium sulfate heptahydrate will undergo multiple crystal form transformations and melting processes, and finally form magnesium sulfate monohydrate (MgSO4·H2O) at 149 DEG C, and finally completely lose the crystal water to become anhydrous magnesium sulfate at 285 DEG C.

[0053] With the rise of the temperature, the sealing cavity 1 softens and the strength is low, the high-pressure water vapor formed by the crystal water at high temperature breaks the cavity shell wall and is released to the battery interior in a jet shape to contact the electrode sheet and the electrolyte. The water reacts with the lithium salt, lithium ion and organic lithium salt in the SEI film of the electrolyte:

[0054] 3H2O+LiPF6→PF5+6HF+LiOH;

[0055] H2O+Li + +e - →LiOH+0.5H2;

[0056] H2O+(CH2OCO2Li)2→Li2CO3+CO

[0057] In the reaction process, the crystal water is removed at high temperature and forms water vapor, which rapidly reacts with lithium salt, consumes active lithium, and reduces the heat reaction of the heat accumulation process in the early stage of thermal runaway. The reaction temperature before triggering thermal runaway is greatly reduced, the battery temperature is lower than the triggering temperature of thermal runaway, and thermal runaway is effectively avoided.

[0058] The above merely describes preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application is within the scope of the present application.

Claims

1. A lithium-ion battery comprising a self-destroying device, characterized in that, The self-destruction device comprises a sealed cavity (1) made of polymer material and a hydrate containing crystal water arranged in the sealed cavity (1), the sealed cavity (1) is arranged in the redundant space of the lower plastic (2) of the top cover of the lithium ion battery, when the lithium ion battery is heated to a preset temperature, the self-destruction device is self-destructed, that is, the hydrate containing crystal water is decomposed and dehydrated to cause the sealed cavity (1) to be deformed and broken at the same time of being heated.

2. The lithium-ion battery of claim 1, wherein, The reinforced rib avoidance position on the lower plastic (2) is the mounting space of the sealed cavity (1).

3. The lithium-ion battery of claim 1, wherein the lithium-ion battery is a lithium-ion battery having a capacity of at least 1 Ah. The upper surface of the sealed cavity (1) is matched with the lower surface of the lower plastic (2) to form an assembly structure, and the sealed cavity (1) is fixed in the lower plastic (2) through the structure assembly. And / or, the sealed cavity (1) is fixed in the lower plastic (2) through adhesive bonding.

4. The lithium-ion battery of claim 1, wherein the lithium-ion battery is a lithium-ion battery having a capacity of at least 1 Ah. The lithium ion battery is a square battery. And / or, the thickness direction of the pole piece of the lithium ion battery is perpendicular to the thickness direction of the self-destruction device. And / or, the pole piece of the lithium ion battery is any one of a laminated piece or a wound structure.

5. The lithium-ion battery of claim 1, wherein the lithium-ion battery is a lithium-ion battery. The hydrate containing crystal water comprises FeSO4·7H2O or MgSO4·7H2O.

6. The lithium-ion battery as described in claim 1, characterized in that, The wall thickness of the sealed cavity (1) is 0.1-0.5 mm; and / or, the sealed cavity (1) is prepared by an integral injection molding method, a lower surface is reserved for filling, and the filling port is used for loading the hydrate containing crystal water.

7. The lithium-ion battery as described in claim 1, characterized in that, The material of the sealed cavity (1) comprises PC and PP.

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