CN116937039B

CN116937039B - Battery pack, method for manufacturing battery pack and power utilization device

Info

Publication number: CN116937039B
Application number: CN202311194516.XA
Authority: CN
Inventors: 王勇
Original assignee: Contemporary Amperex Technology Co Ltd
Current assignee: Contemporary Amperex Technology Co Ltd
Priority date: 2023-09-15
Filing date: 2023-09-15
Publication date: 2024-01-23
Anticipated expiration: 2043-09-15
Also published as: CN116937039A

Abstract

The application discloses a battery package, method of preparing battery package, power consumption device, battery package includes: the battery box comprises an upper box body and a lower box body, wherein the upper box body is covered on the lower box body and forms a closed space; the first encapsulating layer is positioned at one side of the closed space, which is close to the lower box body, and comprises a first encapsulating adhesive and a plurality of battery monomers, wherein the first encapsulating adhesive is positioned between adjacent battery monomers and covers the surfaces of the battery monomers; the second encapsulating layer is positioned at one side of the closed space, which is close to the upper box body, and comprises a second encapsulating adhesive; the density of the first pouring sealant is smaller than that of the second pouring sealant, and the bonding strength of the second pouring sealant is larger than that of the first pouring sealant. Thus, a battery pack having both a higher energy density of quality and superior impact resistance can be obtained.

Description

Battery pack, method for manufacturing battery pack and power utilization device

Technical Field

The application relates to the technical field of batteries, in particular to a battery pack, a method for preparing the battery pack and an electric device.

Background

With the continuous consumption of natural resources such as petroleum, natural gas, coal and the like, the energy crisis faced by human beings is continuously aggravated. In recent years, the battery is widely applied to energy storage power supply systems such as hydraulic power, firepower, wind power and solar power stations, and a plurality of fields such as electric tools, electric bicycles, electric motorcycles, electric automobiles, military equipment, aerospace and the like, and the crisis of natural resources is effectively relieved. The battery is generally assembled in an integrated manner in a battery pack form, and in each assembly of the electric automobile, the battery pack needs to be heavier due to lower mass energy density of the battery pack to meet the endurance requirement, and generally, the total weight of the battery pack accounts for about 30% of the total weight of the whole automobile. However, the too heavy power battery pack greatly influences the cruising ability of the electric automobile, so that the cruising performance of the electric automobile is difficult to effectively improve.

It should be noted that the foregoing statements are merely to provide background information related to the present application and may not necessarily constitute prior art.

Disclosure of Invention

In a first aspect of the present application, the present application proposes a battery pack comprising: the battery box comprises an upper box body and a lower box body, wherein the upper box body is covered on the lower box body and forms a closed space; the first encapsulating layer is positioned on one side, close to the lower box body, of the closed space, and comprises a first pouring sealant and a plurality of battery monomers, wherein the first pouring sealant is positioned between adjacent battery monomers and covers the surfaces of the battery monomers; the second encapsulating layer is positioned at one side, close to the upper box body, of the closed space, and comprises second pouring sealant; the density of the first pouring sealant is smaller than that of the second pouring sealant, and the bonding strength of the second pouring sealant is larger than that of the first pouring sealant. Thus, a battery pack having both a higher energy density of quality and superior impact resistance can be obtained.

In some embodiments, the battery cell includes a housing and a top cap assembly having a post disposed thereon, and the first potting adhesive covers at least a sidewall of the post. Thus, the short circuit phenomenon between adjacent battery cells can be reduced.

In some embodiments, the volume of the first pouring sealant is greater than the volume of the second pouring sealant within the enclosed space; optionally, the volume of the first pouring sealant in the closed space is V ₁ The volume of the second pouring sealant in the closed space is V ₂ ，V ₁ ：V ₂ Are (5:2) - (3:2). Thus, a battery pack of suitable density and structural stability can be obtained.

In some embodiments, the first pouring sealant has a density of 0.3g/cm ³ -0.4g/cm ³ The density of the second pouring sealant is 0.7g/cm ³ -0.8g/cm ³ . Thus, a battery pack having a higher quality energy density can be obtained.

In some embodiments, the first potting adhesive has a bonding strength of 2MPa to 3MPa and the second potting adhesive has a bonding strength of 8MPa to 10MPa. Thus, a battery pack having high structural stability can be obtained.

In some embodiments, the first pouring sealant satisfies at least one of the following conditions: the heat conductivity coefficient of the first pouring sealant is 0.01W/(m.K) -0.03W/(m.K); the elastic modulus of the first pouring sealant at 25 ℃ is 150-200 MPa; the flame retardant grade of the first pouring sealant is V0; the first pouring sealant comprises polyurethane substances. Thus, a battery pack having superior flame retardant property and structural strength can be obtained.

In some embodiments, the second pouring sealant satisfies at least one of the following conditions: the heat conductivity coefficient of the second pouring sealant is 0.2W/(m.K) -0.3W/(m.K); the elastic modulus of the second pouring sealant at 25 ℃ is 250MPa-300MPa; the flame retardant grade of the second pouring sealant is V0; the second pouring sealant comprises polyurethane substances. Thus, a battery pack having superior flame retardant property and structural strength can be obtained.

In some embodiments, the battery cell is a cylindrical battery cell. Therefore, the installation of the battery monomer can be facilitated, and the heat dissipation performance of the battery monomer is improved.

In some embodiments, the first pouring sealant is obtained by mixing a first component and a second component, the first component comprising a resin and a foaming agent; the second component comprises an isocyanate cross-linking agent, and the resin reacts with the isocyanate cross-linking agent to generate polyurethane substances. Thereby, the setting of the first pouring sealant can be facilitated.

In some embodiments, the second pouring sealant is mixed from a third component and a fourth component, the third component comprising a resin; the fourth component comprises an isocyanate cross-linking agent, and the resin reacts with the isocyanate cross-linking agent to generate polyurethane substances. Thereby, the setting of the second pouring sealant can be facilitated.

In a second aspect of the present application, the present application proposes a method of preparing the aforementioned battery pack, comprising: placing a battery monomer in a lower box body, injecting a first pouring sealant to be foamed into the lower box body, and covering an upper box body on the lower box body to form a closed space so that the first pouring sealant to be foamed foams in the closed space to obtain a first pouring sealant layer; and injecting a second pouring sealant from the opening of the upper box body to obtain a second pouring sealant layer so as to fill the closed space. Thus, the battery pack can be obtained by a relatively simple method.

In some embodiments, the first pouring sealant is obtained by mixing a first component and a second component, wherein the first component comprises 50-70 parts by weight of resin, 1-3 parts by weight of catalyst and 5-10 parts by weight of foaming agent; the second component includes an isocyanate-based crosslinker. Therefore, the first component and the second component can be stored separately, and the storage and the transportation are convenient.

In some embodiments, the first component has a viscosity of 800cps to 1500cps and a density of 1.0g/cm ³ -1.3g/cm ³ The method comprises the steps of carrying out a first treatment on the surface of the The viscosity of the second component is 250cps to 800cps, and the density of the second component is 1.0g/cm ³ -1.3g/cm ³ . Thus, the first component can be crosslinked and cured when mixed with the second component, and foamed.

In some embodiments, the mass of the first component in the first pouring sealant is m _1-1 The mass of the second component in the first pouring sealant is m _1-2 ，m _1-1 :m _1-2 Is (100:70) - (100:90). Thus, the first pouring sealant can be obtained by mixing the first component and the second component.

In some embodiments, the first component meets at least one of the following conditions: the resin includes at least one of a polyether polyol and a polyester polyol; the number average molecular weight of the resin is 5000-10000; the catalyst comprises at least one of a tertiary amine catalyst and an organotin catalyst; the foaming agent comprises water.

In some embodiments, the isocyanate-based cross-linking agent includes at least one of diphenylmethane diisocyanate and polymethylene polyphenyl isocyanate. Thus, the polyurethane substance can be produced by the crosslinking reaction between the isocyanate crosslinking agent and the resin, and the foaming agent can be foamed.

In some embodiments, the second pouring sealant is obtained by mixing a third component and a fourth component, wherein the third component comprises 60-80 parts by weight of resin and 0.1-0.5 parts by weight of catalyst; the fourth component comprises 40-60 parts by weight of isocyanate cross-linking agent, 15-30 parts by weight of filler and 10-30 parts by weight of flame retardant. Therefore, the third component and the fourth component can be stored separately, and the storage and the transportation are convenient.

In some embodiments, the viscosity of the third component is 2000cps to 2500cps and the density of the third component is 0.7g/cm ³ -0.8g/cm ³ The method comprises the steps of carrying out a first treatment on the surface of the The viscosity of the fourth component is 2500cps-3000cps, and the density of the fourth component is 0.7g/cm ³ -0.8g/cm ³ 。

In some embodiments, the mass of the third component in the second pouring sealant is m _2-1 The mass of the fourth component in the second pouring sealant is m _2-2 ，m _2-1 :m _2-2 Are (90:100) - (110:100). Thus, the second pouring sealant can be obtained by mixing the third component and the fourth component.

In some embodiments, the third component meets at least one of the following conditions: the resin includes at least one of a polyether polyol and a polyester polyol; the number average molecular weight of the resin is 5000-15000; the catalyst comprises an organotin catalyst.

In some embodiments, the fourth component meets at least one of the following conditions: the isocyanate cross-linking agent comprises aliphatic isocyanate; the filler comprises hollow glass beads; the flame retardant comprises a phosphate flame retardant.

In a third aspect of the present application, the present application proposes an electrical device comprising the aforementioned battery pack, or a battery pack prepared by the aforementioned method. Thus, the power utilization device includes all the features and advantages of the foregoing battery pack and the method for preparing the battery pack, which are not described in detail herein.

Drawings

The foregoing and/or additional aspects and advantages of the present application will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings, wherein:

fig. 1 is a schematic structural view of a battery pack according to an embodiment of the present application;

FIG. 2 is a schematic illustration of a battery cell according to an embodiment of the present application;

fig. 3 is an exploded view of a battery cell according to an embodiment of the present application shown in fig. 2;

fig. 4 is a schematic view of a battery module according to an embodiment of the present application;

fig. 5 is a partial schematic structure of a battery pack according to still another embodiment of the present application;

FIG. 6 is an exploded view of the battery pack of one embodiment of the present application shown in FIG. 5;

FIG. 7 is a schematic diagram of an electrical device according to an embodiment of the present application;

fig. 8 is a flow chart illustrating a method of preparing a battery pack according to an embodiment of the present application;

fig. 9 is a schematic diagram of the mechanical shock pulse tolerance ranges when testing a battery pack in the present application.

Reference numerals illustrate:

1, a battery pack; 2, upper box body; 3, lower box body; 4, a battery module; 5, a battery cell; 6, fastening pieces;

10 a first potting layer; 11 a first pouring sealant; a second potting layer 20; a second pouring sealant 21; 51 a housing; 52 electrode assembly; 53 a top cover assembly; 54 positive electrode posts; 55 negative electrode post.

Detailed Description

Embodiments of the present application are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals refer to the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary only for the purpose of explaining the present application and are not to be construed as limiting the present application.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used in the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the present application; unless otherwise indicated, the numerical values of the parameters set forth in this application may be measured by various measurement methods commonly used in the art (e.g., may be tested according to the methods set forth in the examples of this application).

The terms "comprising" and "having" and any variations thereof in the description and claims of the present application are intended to be open-ended, i.e., to include the material indicated herein, but not to exclude other aspects.

In the description of the present application, all numbers disclosed herein are approximate, whether or not words of "about" or "about" are used. The numerical value of each number may vary by less than 10% or reasonably as considered by those skilled in the art, such as 1%, 2%, 3%, 4% or 5%.

In the description of the present application, the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. The "first feature" and "second feature" may include one or more of the features.

In the description of the present application, the meaning of "plurality" is two or more.

The battery pack usually contains tens or even hundreds of battery cells, and a great amount of heat is generated when the battery cells work, so that the temperature of the whole battery pack is too high, and the problem of thermal runaway spontaneous combustion is caused. By improving the structural members and the parts in the battery pack, the problem of overhigh temperature during the operation of the battery pack can be alleviated. Specifically, when the structural member is replaced by the adhesive to fix the structure of the battery monomer, the adhesive can play a role in flame retardance and heat insulation while playing a role in fixing.

The use of the adhesive in the battery pack is mainly based on pouring sealant, but the use of the pouring sealant can increase the weight of the battery pack, reduce the quality energy density of the battery pack and reduce the endurance mileage. The pouring sealant also has the advantages of lower bonding strength and higher heat conductivity coefficient, so that the pouring sealant cannot fully fix the battery cells and can prevent heat from being transferred between adjacent battery cells.

In the application, the first pouring sealant with smaller density is used for pouring and sealing the battery monomers, so that the first pouring sealant fills gaps among the battery monomers and covers the surfaces of the battery monomers, and the gaps among adjacent battery monomers, the positive electrode and the negative electrode are poured and sealed, so that the risk of thermal runaway of the adjacent battery monomers caused by thermal runaway of the single battery monomer can be effectively relieved by utilizing the flame-retardant and heat-insulating characteristics of the body of the pouring sealant while the battery monomers are fixed, and further the risk of thermal runaway spontaneous combustion of the battery pack is effectively reduced; the second pouring sealant with larger bonding strength is used for pouring and sealing the gap between the battery monomer and the upper box body of the battery pack, and the battery pack is combined and poured and sealed by the pouring sealant with two different characteristics, so that the high-quality energy density requirement of the battery pack can be met, and the vibration resistance and impact resistance requirements of the battery can also be met.

In a first aspect of the present application, the present application proposes a battery pack, referring to fig. 1, comprising: the battery box comprises an upper box body 2 and a lower box body 3, wherein the upper box body 2 is covered on the lower box body 3 and forms a closed space; the first potting layer 10, the first potting layer 10 is located at one side of the closed space close to the lower box body 3, the first potting layer 10 comprises a first potting adhesive 11 and a plurality of battery cells 5, the battery cells 5 are arranged in the lower box body 3 at intervals, the poles of the battery cells 5 are arranged towards the same side, for example, the poles of the battery cells 5 are arranged towards one side of the upper box body 2, the first potting adhesive 11 is located between the adjacent battery cells 5, and covers the surfaces of the battery cells 5; the second encapsulating layer 20 is positioned at one side of the closed space close to the upper box body 2, and the second encapsulating layer 20 comprises a second pouring sealant 21; wherein, the density of the first pouring sealant 11 is smaller than that of the second pouring sealant 21, and the bonding strength of the second pouring sealant 21 is larger than that of the first pouring sealant 11.

If the battery pack is completely encapsulated by only the first pouring sealant, the impact resistance of the battery pack is poor due to the fact that the adhesive strength of the first pouring sealant with low density is low, and the battery pack is in risk of battery monomer falling in the processes of vibration impact test and long-term running of the electric automobile; if only the second pouring sealant is used for completely pouring the battery pack, the second pouring sealant with larger bonding strength is higher in density, and only the second pouring sealant is used for pouring the battery pack, so that the quality energy density of the battery pack is too low, and the light-weight requirement cannot be fully met. The lower box body with larger volume in the battery pack is filled with the first filling and sealing glue with lower density, specifically, the gaps among the battery monomers are filled and sealed, the battery monomers are fixed, the battery can have higher quality energy density, and the risk of thermal runaway of adjacent battery monomers caused by thermal runaway of single battery monomers is relieved by utilizing the flame-retardant and heat-insulating properties of the body of the first filling and sealing glue; the second pouring sealant with higher bonding strength is utilized to fill the gap part, which is not filled by the first pouring sealant, in the battery pack, so that the structural stability of the battery can be effectively improved, and the shock resistance is further improved. Thus, the battery pack with higher quality energy density and better shock resistance is obtained through the combined encapsulation of the first pouring sealant and the second pouring sealant.

It will be appreciated that there may be an uneven surface, or other structural defect, at the interface of the first potting layer and the second potting layer in the battery pack, and thus there may be a trace mixing of the first potting adhesive and the second potting adhesive at the interface of the two layers in contact. In the long-term storage and working process, the layer structures of the first encapsulating layer and the second encapsulating layer in the battery pack can be kept independent and complete, and no further mixing can occur between the first encapsulating adhesive and the second encapsulating adhesive.

In some embodiments, the first pouring sealant may be a foaming type pouring sealant, for example, the first pouring sealant may be a foaming type polyurethane pouring sealant, and a large number of bubbles exist inside the foaming type pouring sealant after foaming, so that the foaming type pouring sealant has a lower density under the condition of the same volume, so that the overall quality of the battery pack can be reduced, and the quality energy density of the battery pack can be increased. The foaming pouring sealant also has the characteristics of flame retardance and lower bonding strength.

In some embodiments, the second potting adhesive may be a non-foaming potting adhesive, for example, the second potting adhesive may be a polyurethane potting adhesive containing hollow glass microspheres. The non-foaming pouring sealant has higher bonding strength, so that the internal structural stability of the battery pack can be effectively improved, and the risk of falling off of the battery monomer caused by external force impact is reduced. The non-foaming pouring sealant also has the characteristic of higher density.

In some embodiments, referring to fig. 1, 2 and 3, the battery cell 5 includes a case 51 and a top cap assembly 53, the top cap assembly 53 is provided with a post, the post includes a positive post 54 and a negative post 55, and the first potting adhesive 11 covers at least a sidewall of the post.

For the battery cell, the top cover assembly 53 may be connected to the housing 51 by a welding process, and the positive electrode post 54 and the negative electrode post 55 on the upper cover plate of the top cover assembly 53 are the positive electrode and the negative electrode of the external conductive circuit of the battery cell. Therefore, sealability, electrical insulation and the like of the polar posts are significant for the stable operation of the battery cells. In the battery pack, a creepage phenomenon may exist between the poles of adjacent battery cells, thereby causing a short circuit between the adjacent battery cells. By enabling the first pouring sealant to cover the side wall of the pole, creepage short circuit between the poles of adjacent battery monomers can be effectively relieved.

In some embodiments, the volume of the first potting adhesive 11 in the closed space formed by the upper case 2 and the lower case 3 is larger than the volume of the second potting adhesive 21, for example, the volume of the first potting adhesive in the closed space is V ₁ The volume of the second pouring sealant in the closed space is V ₂ ，V ₁ ：V ₂ Are (5:2) - (3:2).

By way of example, V ₁ ：V ₂ May be (5:2), (4.5:2), (4:2), (3.5:2) or (3:2).

When the volume of the first pouring sealant and the volume of the second pouring sealant in the closed space meet the proportional relation, the battery pack has higher mass energy density and structural stability.

In some embodiments, the first pouring sealant has a density of 0.3g/cm ³ -0.4g/cm ³ The density of the second pouring sealant is 0.7g/cm ³ -0.8g/cm ³ 。

As an example, the density of the first pouring sealant may be 0.3g/cm ³ 、0.32g/cm ³ 、0.34g/cm ³ 、0.36g/cm ³ 、0.38g/cm ³ Or 0.4g/cm ³ 。

As an example, the density of the second pouring sealant may be 0.7g/cm ³ 、0.72g/cm ³ 、0.74g/cm ³ 、0.76g/cm ³ 、0.78g/cm ³ Or 0.8g/cm ³ 。

The "density of the pouring sealant" in this application is in the meaning well known in the art and can be measured using instruments and methods well known in the art. As an example, the density of the pouring sealant can be tested with reference to GB/T13354, in particular, the following method can be seen:

instrument and apparatus: weighing cup: a metal cup having a capacity of 37.00mL at 20 ℃ (note: domestic weighing cup meeting the present standard is named "QI313 specific gravity cup"); constant temperature bath or constant temperature chamber: can keep 23+/-1 ℃; and (3) a balance: the sensing amount is 0.001g; a thermometer: 0-50 deg.c and indexing 1 deg.c.

The experimental steps are as follows:

(1) A sample of the pouring sealant was prepared sufficient to perform three trials.

(2) The weighing cup is washed with a volatile solvent and dried.

(3) Filling the evenly stirred pouring sealant sample into a weight cup at the temperature below 25 ℃, then closing a cover, keeping an overflow port open, and then wiping off overflows by using a volatile solvent.

(4) The weighing cup containing the pouring sealant sample is placed in a constant temperature bath or a constant temperature chamber, and the sample is kept at a constant temperature of 23+/-1 ℃.

(5) The spill was wiped off with solvent and the cuvette was then weighed with its mating weight to the nearest 0.001g.

(6) Each pouring sealant sample was tested three times with the arithmetic mean of the three data as the test result.

The calculation method comprises the following steps:

wherein: ρ is the density of the pouring sealant in g/cm ³ ；m ₁ The mass of the empty weight cup is g; m is m ₂ Is a dress

The weight cup mass of the full pouring sealant sample is given in g;37 is the weight cup capacity in cm ³ 。

In some embodiments, the first potting adhesive has a bond strength of 2MPa to 3MPa and the second potting adhesive has a bond strength of 8MPa to 10MPa. Thus, a battery pack having high structural stability can be obtained.

As an example, the adhesive strength of the first potting adhesive may be 2MPa, 2.2MPa, 2.4MPa, 2.6MPa, 2.8MPa, or 3MPa.

As an example, the adhesive strength of the second potting adhesive may be 8MPa, 8.2MPa, 8.4MPa, 8.6MPa, 8.8MPa, 9MPa, 9.2MPa, 9.4MPa, 9.6MPa, 9.8MPa, or 10MPa.

The term "adhesive strength of a pouring sealant" as used herein is intended to mean a value known in the art, and can be measured by an instrument and a method known in the art. As an example, the adhesive strength of the pouring sealant can be tested with reference to GB/T7124, in particular, the following method can be seen:

(1) Sample preparation: the shearing sample piece is manufactured with reference to GB/T7124, a clamp is used for accurately positioning the cementing piece, and a teflon adhesive tape is used for limiting the gluing width, so that the length of a cementing surface is controlled to be 12.5+/-0.5 mm; the thickness of the adhesive layer is designed to be 0.25 plus or minus 0.05mm except for special requirements, and can be controlled by inserting spacing wires which are parallel to the force application direction.

(2) A base material: the test piece materials are divided into materials such as electrophoresis steel, 3003Al, 6063Al, parting agent blue film, parting paper blue film, hot pressing film, PC and the like, and the materials are regulated by the certification report. The surface of the bonding part of the base material is cleaned by alcohol before bonding, so that no grease and other pollutants are ensured, and the surface of the bonding part is consistent with the base material of the actual bonding part.

(3) The glue mixing requirement is as follows: in the sample preparation process, the correct proportion (no color difference) of the first component and the second component is required to be determined, and in order to avoid bubble residues when glue is mixed, a glue gun and a static glue mixing pipe are used for gluing, or manual glue mixing is carried out, and then a deaeration machine is used for mixing and deaeration for 2 minutes, so that the sample is prepared.

(4) The preparation process comprises the following steps: the glue sample is completed within a prescribed operating time, taking care to remove the glue flash. The glued sample is cured according to the specified conditions and then tested under the specified conditions.

(5) Test requirements: the tensile tester performs the test at a constant test speed of 5mm/min. In order to make the sample piece stressed parallel to the cementing plane, a gasket with the thickness equivalent to that of the test piece is respectively padded at the upper and lower test chucks. If the pull-off displacement is to be tested, an extensometer is required to perform the measurement.

As an example, the thermal conductivity of the first potting adhesive may be 0.01W/(m.k), 0.012W/(m.k), 0.015W/(m.k), 0.018W/(m.k), 0.02W/(m.k), 0.022W/(m.k), 0.025W/(m.k), 0.028W/(m.k), or 0.03W/(m.k).

When the coefficient of heat conductivity of the first pouring sealant is 0.01W/(m.K) -0.03W/(m.K), the heat conductivity of the first pouring sealant is poor, and when a certain battery monomer in the battery pack is in thermal runaway, the first pouring sealant between adjacent battery monomers can effectively relieve the spreading of heat between the adjacent battery monomers, so that the risk of thermal runaway of the adjacent battery monomers caused by the thermal runaway of the single battery monomer is relieved.

As an example, the elastic modulus of the first potting adhesive at 25 ℃ may be 150MPa, 155MPa, 160MPa, 165MPa, 170MPa, 175MPa, 180MPa, 185MPa, 190MPa, 195MPa or 200MPa.

When the elastic modulus of the first pouring sealant is 150-200 MPa at 25 ℃, and the battery pack is impacted by external force near one side of the first pouring sealant, the first pouring sealant can absorb impact energy, and the influence of the external force on the battery monomer is reduced.

As an example, the first pouring sealant may be a polyurethane substance, for example, the polyurethane substance may be obtained by reacting a polyol substance with an isocyanate substance, and at the same time, since the isocyanate may function as a foaming auxiliary agent, for example, the isocyanate may be foamed after being mixed with water, the polyurethane type pouring sealant may be obtained by mixing the polyol substance, water, and the isocyanate substance.

As an example, the thermal conductivity of the second potting adhesive may be 0.2W/(m.k), 0.22W/(m.k), 0.24W/(m.k), 0.26W/(m.k), 0.28W/(m.k), or 0.3W/(m.k).

When the heat conductivity coefficient of the second pouring sealant is 0.2W/(m.K) -0.3W/(m.K), the heat conductivity of the second pouring sealant is poor, and when the temperature inside the battery pack is high, the second pouring sealant can delay the internal temperature of the battery pack from rising suddenly, so that the risk of spontaneous combustion of the battery pack is reduced.

As an example, the elastic modulus of the second potting adhesive at 25 ℃ may be 250MPa, 255MPa, 260MPa, 265MPa, 270MPa, 275MPa, 280MPa, 285MPa, 290MPa, 295MPa, or 300MPa.

When the elastic modulus of the second pouring sealant is 250-300 MPa at 25 ℃, and the battery pack is impacted by external force near one side of the second pouring sealant, the second pouring sealant can absorb impact energy, and the influence of the external force on the battery monomer is reduced.

As an example, the second pouring sealant may be a polyurethane substance, for example, the polyurethane substance may be obtained by reacting a polyol substance with an isocyanate substance, and thus the polyurethane pouring sealant may be obtained by mixing the polyol substance and the isocyanate substance.

The "fire retardant rating of a pouring sealant" herein is in the meaning well known in the art and can be measured using instruments and methods well known in the art. As an example, the flame retardant rating of a pouring sealant can be tested with reference to UL94-V standards. The flame retardant performance increases in sequence with the flame retardant grades V2, V1, V0.

The "coefficient of thermal conductivity of a pouring sealant" in this application is in the sense known in the art and can be measured using instruments and methods known in the art. As an example, the thermal conductivity of a pouring sealant can be tested with reference to ISO22007-2, see in particular the following method:

the transient plane heat source method (Hot Disk) is adopted for testing, the whole testing system is placed in a constant-temperature sample cavity, firstly, a sample/probe is fixed by a clamp, and before an experiment, an electric bridge is balanced. The initial resistance of the probe is 1-50 ohms, and the current is ensured not to exceed 1mA by balancing the voltage of the bridge. A heat pulse is applied to the sample and the temperature is recorded for a predetermined measurement time.

The "modulus of elasticity" of the pouring sealant of the present application is a meaning well known in the art and can be measured by an instrument and method well known in the art. As an example, the modulus of elasticity of the pouring sealant can be tested with reference to IPC-TM-650.2.4.24.4, dma, see in particular the following method:

Cutting the solidified adhesive tape, wherein the size is as follows: 50mm long, 7mm wide and 2mm thick.

(1) The width and thickness of the sample were measured to 0.02mm, 3 points were measured within the gauge length of the sample, and the arithmetic average was taken.

(2) And arranging a deformation measuring device in the gauge length of the sample, selecting proper magnification, testing at a speed of 1+/-0.5 mm/min, and selecting corresponding vibration frequency, wherein when the deformation reaches about 0.5%, the length of a line segment of a load-deformation curve is larger than 100mm, and the included angle between the line segment and a coordinate axis is within a range of 30-60 degrees.

(3) After the parameter setting is finished, the device starts to test, and the result is automatically displayed by the device.

(4) And recording a test result.

In some embodiments, the first pouring sealant is obtained by mixing a first component and a second component, the first component comprising a resin and a foaming agent; the second component comprises isocyanate cross-linking agent, and the resin reacts with the isocyanate cross-linking agent to generate polyurethane substance.

The foaming reaction can be carried out by mixing the foaming agent and the foaming auxiliary agent (isocyanate cross-linking agent) at normal temperature, and the cross-linking reaction of the resin and the isocyanate cross-linking agent to generate polyurethane can be initiated at normal temperature, so that the first pouring sealant can be filled after the first component and the second component are mixed.

In some embodiments, the second pouring sealant is obtained by mixing a third component and a fourth component, the third component comprising a resin; the fourth component comprises isocyanate cross-linking agent, and the resin reacts with the isocyanate cross-linking agent to generate polyurethane substance.

The resin and the isocyanate cross-linking agent are mixed at normal temperature to react to generate polyurethane substances, so that the third component and the fourth component are mixed to fill the second pouring sealant.

In some embodiments, the battery cells 5 may be assembled into the battery module 4, and the number of batteries contained in the battery module 4 may be one or more, and the specific number may be selected by one skilled in the art according to the application and capacity of the battery module. Specifically, the battery pack 1 may further include: and a fastener 6, wherein the fastener 6 fixes a plurality of battery cells 5 arranged along the same direction, the plurality of battery cells 5 are connected in series or in parallel, and the plurality of battery cells 5 in the form of the battery module 4 can be obtained through the fixation of the fastener 6. Therefore, the first pouring sealant 11 can cover the battery module 4, so that the functions of fixing the battery module 4 and resisting flame and heat are achieved.

As an example, referring to fig. 4, in the battery module 4, a plurality of battery cells 5 may be sequentially arranged in the length direction of the battery module 4. Of course, the plurality of battery cells 5 may be arranged in any other manner, and the plurality of battery cells may be fixed by the fasteners 6.

In some embodiments, the above battery modules may be further assembled into a battery pack, and the number of battery modules included in the battery pack may be one or more, and a specific number may be selected by those skilled in the art according to the application and capacity of the battery pack.

Fig. 5 and 6 are battery packs 1 as an example. Referring to fig. 5 and 6, a battery case and a plurality of battery modules 4 disposed in the battery case may be included in the battery pack 1. The battery box includes an upper box body 2 and a lower box body 3, and the upper box body 2 can be covered on the lower box body 3 and forms a closed space for accommodating the battery module 4. The plurality of battery modules 4 may be arranged in the battery box in any manner.

Typically, the battery cell includes a positive electrode tab, a negative electrode tab, an electrolyte, and a separator. In the process of charging and discharging the battery cell, active ions are inserted and separated back and forth between the positive electrode plate and the negative electrode plate. The electrolyte plays a role in ion conduction between the positive electrode plate and the negative electrode plate. The isolating film is arranged between the positive pole piece and the negative pole piece, and mainly plays a role in preventing short circuit between the positive pole piece and the negative pole, and meanwhile ions can pass through the isolating film.

[ Positive electrode sheet ]

The positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer disposed on at least one surface of the positive electrode current collector, the positive electrode active material layer including a positive electrode active material.

As an example, the positive electrode current collector has two surfaces opposing in its own thickness direction, and the positive electrode active material layer is provided on either one or both of the two surfaces opposing the positive electrode current collector.

In some embodiments, the positive current collector may employ a metal foil or a composite current collector. For example, as the metal foil, aluminum foil may be used. The composite current collector may include a polymeric material base layer and a metal layer formed on at least one surface of the polymeric material base layer. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel alloy, titanium alloy, silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

In some embodiments, when the battery is a lithium ion battery, the positive electrode active material may be a positive electrode active material for lithium ion batteries, which is well known in the art.

As an example, the positive electrode active material may include at least one of the following materials: olivine structured lithium-containing phosphates, lithium transition metal oxides and their respective modified compounds. However, the present application is not limited to these materials, and other conventional materials that can be used as a battery positive electrode active material may be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium transition metal oxides may include, but are not limited to, lithium cobalt oxide (e.g., liCoO) ₂ ) Lithium nickel oxide (e.g. LiNiO) ₂ ) Lithium manganese oxide (e.g. LiMnO ₂ 、LiMn ₂ O ₄ ) Lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (e.g., liNi) _1/3 Co _1/3 Mn _1/3 O ₂ (also referred to as NCM) ₃₃₃ ）、LiNi _0.5 Co _0.2 Mn _0.3 O ₂ (also referred to as NCM) ₅₂₃ ）、LiNi _0.5 Co _0.25 Mn _0.25 O ₂ (also referred to as NCM) ₂₁₁ ）、LiNi _0.6 Co _0.2 Mn _0.2 O ₂ (also referred to as NCM) ₆₂₂ ）、LiNi _0.8 Co _0.1 Mn _0.1 O ₂ (also referred to as NCM) ₈₁₁ ) Lithium nickel cobalt aluminum oxide (e.g. LiNi _0.8 Co _0.15 Al _0.05 O ₂ ) Modified compounds thereofAt least one of the following. Examples of olivine structured lithium-containing phosphates may include, but are not limited to, lithium iron phosphate (e.g., liFePO ₄ (also abbreviated as LFP)), composite material of lithium iron phosphate and carbon, and manganese lithium phosphate (such as LiMnPO) ₄ ) At least one of a composite material of lithium manganese phosphate and carbon, and a composite material of lithium manganese phosphate and carbon. The modifying compound of each material can be doping modification and/or surface coating modification of the material.

The battery is charged and discharged with the release and consumption of Li, and the molar contents of Li are different when the battery is discharged to different states. In the list of the positive electrode active materials in the application, the molar content of Li is the initial state of the materials, namely the state before charging, and the molar content of Li is changed after the positive electrode active materials are applied to a battery system and undergo charge and discharge cycles.

In the list of the positive electrode active materials in the application, the molar content of O is only a theoretical state value, the molar content of oxygen is changed due to lattice oxygen release, and the actual molar content of O can float.

In some embodiments, when the battery is a sodium-ion battery, the positive active material may be a positive active material for a sodium-ion battery, as known in the art.

As an example, the positive electrode active material may include at least one of the following materials: sodium transition metal oxides, polyanion compounds and Prussian blue sodium compounds, and their respective modified compounds. However, the present application is not limited to these materials, and other conventional materials that can be used as a battery positive electrode active material may be used. The modifying compound of each material can be doping modification and/or surface coating modification of the material.

In some embodiments, the transition metal in the sodium transition metal oxide may be at least one of Ti, V, mn, co, ni, fe, zn, V, zr, ce, cr, cu. The chemical formula of the sodium transition metal oxide can satisfy Na _x MO ₂ Wherein M comprises at least one of Ti, V, mn, co, ni, fe, zn, V, zr, ce, cr, cu, 0 < x.ltoreq.1.

In some embodiments, the polyanionic compound may be a polymer having sodium ions, transition metal ions, and tetrahedra (YO ₄ ) ^n- A class of compounds of anionic units. Wherein the transition metal may include at least one of Mn, fe, ni, co, cr, cu, ti, zn, V, zr, ce; y may include at least one of P, S, si; n represents (YO) ₄ ) ^n- Is a valence state of (2).

In some embodiments, the polyanionic compound may also be a polymer having sodium ions, transition metal ions, tetrahedra (YO ₄ ) ^n- A class of compounds of anionic units and halogen anions. The transition metal may include at least one of Mn, fe, ni, co, cr, cu, ti, zn, V, zr, ce; y may include at least one of P, S, si, n represents (YO ₄ ) ^n- The halogen may include at least one of F, cl, br.

In some embodiments, the polyanionic compound may also be a polymer having sodium ions, tetrahedra (YO ₄ ) ^n- Anion unit, polyhedral unit (ZO _y ) ^m+ And optionally a halogen anion. M may include at least one of Mn, fe, ni, co, cr, cu, ti, zn, V, zr and Ce, Y may include at least one of P, S, si, n represents (YO ₄ ) ^n- Z represents a transition metal, m represents (ZO _y ) ^m+ The halogen may include at least one of F, cl, br.

As an example, the polyanionic compound may satisfy the chemical formula NaFePO ₄ 、Na ₃ V ₂ (PO ₄ ) ₃ (sodium vanadium phosphate, NVP for short), na ₄ Fe ₃ (PO ₄ ) ₂ (P ₂ O ₇ )、NaM’PO ₄ F (M' is at least one of V, fe, mn and Ni) and Na ₃ (VO _y ) ₂ (PO ₄ ) ₂ F _3-2y At least one of (0.ltoreq.y.ltoreq.1).

In some embodiments, the Prussian blue-based compound may be a compound having sodium ions and transition metalsIon and cyanide ion (CN) ^- ) Is a compound of the formula (I). The transition metal may include at least one of Mn, fe, ni, co, cr, cu, ti, zn, V, zr and Ce.

As an example, the Prussian blue type compound may satisfy the chemical formula Na _a Me _b Me’ _c (CN) ₆ Wherein Me and Me' each independently comprise at least one of Ni, cu, fe, mn, co, zn, 0 < a.ltoreq.2, 0 < b < 1,0 < c < 1.

The battery can be charged and discharged with Na release and consumption, and the molar content of Na is different when the battery is discharged to different states. In the list of the positive electrode active material, the molar content of Na is the initial state of the material, namely the state before feeding, and the molar content of Na is changed after the positive electrode active material is applied to a battery system and subjected to charge-discharge cycle.

In some embodiments, the positive electrode active material layer may further optionally include a binder.

As an example, the adhesive may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), a vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, a vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, a tetrafluoroethylene-hexafluoropropylene copolymer, and a fluoroacrylate resin.

In some embodiments, the positive electrode active material layer may further optionally include a conductive agent.

As an example, the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

In some embodiments, the positive electrode sheet may be prepared by: dispersing the above components for preparing the positive electrode sheet, such as a positive electrode active material, a conductive agent, an adhesive and any other components, in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; and (3) coating the positive electrode slurry on a positive electrode current collector, and obtaining a positive electrode plate after the procedures of drying, cold pressing and the like.

[ negative electrode sheet ]

The negative electrode tab includes a negative electrode current collector and a negative electrode active material layer disposed on at least one surface of the negative electrode current collector, the negative electrode active material layer including a negative electrode active material.

As an example, the anode current collector has two surfaces opposing in its own thickness direction, and the anode active material layer is provided on either one or both of the two surfaces opposing the anode current collector.

In some embodiments, the negative electrode current collector may employ a metal foil or a composite current collector. For example, as the metal foil, copper foil may be used. The composite current collector may include a polymeric material base layer and a metal layer formed on at least one surface of the polymeric material base material. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel alloy, titanium alloy, silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

In some embodiments, the anode active material may employ an anode active material for a battery, which is well known in the art. As an example, the anode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, and the like. The silicon-based material comprises at least one of elemental silicon, silicon oxygen compounds, silicon carbon composites, silicon nitrogen composites and silicon alloys. The tin-based material includes at least one of elemental tin, a tin oxide, and a tin alloy. However, the present application is not limited to these materials, and other conventional materials that can be used as a battery anode active material may be used. These negative electrode active materials may be used alone or in combination of two or more.

In some embodiments, the anode active material layer further optionally includes a binder. The adhesive comprises at least one of Styrene Butadiene Rubber (SBR), polyacrylic acid (PAA), sodium Polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium Alginate (SA), polymethacrylic acid (PMAA) and carboxymethyl chitosan (CMCS).

In some embodiments, the anode active material layer may further optionally include a conductive agent. The conductive agent comprises at least one of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.

In some embodiments, the anode active material layer may optionally further include other adjuvants, such as a thickener (e.g., sodium carboxymethyl cellulose (CMC-Na)), and the like.

In some embodiments, the negative electrode sheet may be prepared by: dispersing the above components for preparing the negative electrode sheet, such as a negative electrode active material, a conductive agent, an adhesive, and any other components, in a solvent (e.g., deionized water) to form a negative electrode slurry; and coating the negative electrode slurry on a negative electrode current collector, and obtaining a negative electrode plate after the procedures of drying, cold pressing and the like.

[ electrolyte ]

The electrolyte plays a role in ion conduction between the positive electrode plate and the negative electrode plate. The type of electrolyte is not particularly limited in this application, and may be selected according to the need. For example, the electrolyte may be liquid, gel, or all solid.

In some embodiments, the electrolyte is an electrolyte. The electrolyte includes an electrolyte salt and a solvent.

In some embodiments, the electrolyte salt includes at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis-fluorosulfonyl imide, lithium bis-trifluoromethanesulfonyl imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalato borate, lithium dioxaato borate, lithium difluorodioxaato phosphate, and lithium tetrafluorooxalato phosphate.

In some embodiments, the solvent comprises at least one of ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethylene propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1, 4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone.

In some embodiments, the electrolyte further optionally includes an additive. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives capable of improving certain properties of the battery, such as additives that improve the overcharge performance of the battery, additives that improve the high or low temperature performance of the battery, and the like.

[ isolation Membrane ]

In some embodiments, a separator is also included in the battery cell. The type of the separator is not particularly limited, and any known porous separator having good chemical stability and mechanical stability may be used.

In some embodiments, the material of the isolation film comprises at least one of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride. The separator may be a single-layer film or a multilayer composite film, and is not particularly limited. When the separator is a multilayer composite film, the materials of the respective layers may be the same or different, and are not particularly limited.

Hereinafter, the battery cells of the present application will be described with reference to the accompanying drawings as appropriate.

In some embodiments, the positive electrode tab, the negative electrode tab, and the separator may be manufactured into an electrode assembly through a winding process or a lamination process.

In some embodiments, the battery cell may include an outer package. The outer package may be used to encapsulate the electrode assembly and electrolyte described above.

In some embodiments, the exterior package of the battery may be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, or the like. The outer package of the battery may also be a pouch, such as a pouch-type pouch. The material of the flexible bag may be plastic, and examples of the plastic include polypropylene, polybutylene terephthalate, and polybutylene succinate.

The shape of the battery cell is not particularly limited in this application, and may be cylindrical, square, or any other shape. For example, fig. 2 is a square-structured battery cell as one example.

In some embodiments, referring to fig. 3, the overpack may include a housing 51 and a cap assembly 53. The housing 51 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate enclose a receiving chamber. The housing 51 has an opening communicating with the accommodating chamber, and the top cover assembly 53 can be provided to cover the opening to close the accommodating chamber. The positive electrode tab, the negative electrode tab, and the separator may be formed into the electrode assembly 52 through a winding process or a lamination process. The electrode assembly 52 is packaged in the receiving chamber. The electrolyte is impregnated in the electrode assembly 52. The number of electrode assemblies 52 included in the battery cells may be one or more, and those skilled in the art may choose according to specific practical requirements.

In some embodiments, the battery cell may be a cylindrical battery cell. Compared with square battery monomers, the production process equipment of the cylindrical battery monomers is high in standardization degree, high in product yield and low in production cost; the battery pack is assembled with lower assembly cost and better heat dissipation performance; the battery is not easy to expand and other defects in the using and transporting processes, and the thermal runaway caused by the penetration of sharp objects is not easy to occur when the hard shell outer package is adopted.

In a second aspect of the present application, the present application proposes a method for preparing the foregoing battery pack, firstly injecting a certain mass of unfoamed first pouring sealant into a lower box of the battery pack, then adding the box to seal the battery pack, and after a certain time, foaming the first pouring sealant to fill a gap between the battery cells, preferably foaming the first pouring sealant to be level with a post of the battery cell, wherein uneven surfaces are generated on the upper surface of the battery cell and/or the battery module due to uneven foaming of the first pouring sealant; and then injecting a second pouring sealant from the opening of the upper box body so as to fill gaps and uneven places among the battery cells, the battery modules and the inner surface of the upper box body, and then completing the complete pouring of the battery pack. Specifically, referring to fig. 8, comprising:

S100: the battery monomer is placed in the lower box body, the first pouring sealant to be foamed is injected into the lower box body, and the upper box body is covered on the lower box body

In some embodiments, in this step, the unfoamed first potting adhesive is added to the lower case containing the battery cells and/or the battery module, and the upper case is covered on the lower case to form a closed space, so that the first potting adhesive to be foamed is foamed in the closed space, thereby obtaining the first potting adhesive of a desired density.

By foaming the unfoamed first pouring sealant in the closed space, the foaming condition of the first pouring sealant can be controlled, and the first pouring sealant with moderate density and proper volume ratio is obtained.

As an example, when foaming is performed in the closed space inside the battery pack, the density of the first potting adhesive after foaming may be made to be 0.3g/cm ³ -0.4g/cm ³ The foaming height of the first pouring sealant can be controlled to be preferably equal to the height of the pole of the battery cell; when the foaming of the first pouring sealant is carried out under the condition of not controlling the external pressure, the density of the freely foamed first pouring sealant, namely the freely foamed density of the first pouring sealant, can reach 0.2g/cm ³ -0.3g/cm ³ The density of the first pouring sealant after free foaming is too small, the bonding strength is correspondingly reduced, the structural stability of the battery pack is poor, and the space reserved for the second pouring sealant can be occupied, so that the overall impact resistance of the battery is obviously reduced.

In some embodiments, the first pouring sealant is obtained by mixing a first component and a second component, the first component comprising 50 parts by weight to 70 parts by weight of a resin, 1 part by weight to 3 parts by weight of a catalyst, 5 parts by weight to 10 parts by weight of a foaming agent; the second component includes an isocyanate-based cross-linking agent.

As an example, the weight part of resin in the first component may be 50, 55, 60, 65, or 70; the weight part of the catalyst in the first component may be 1, 2 or 3; the weight part of the foaming agent in the first component may be 5, 6, 7, 8, 9 or 10.

Because the first pouring sealant is foaming polyurethane pouring sealant, foaming reaction can be carried out by mixing a foaming agent and a foaming auxiliary agent (isocyanate cross-linking agent) at normal temperature, and cross-linking reaction of polyurethane generated by reaction of resin and the isocyanate cross-linking agent can be initiated at normal temperature, the first component and the second component are required to be stored separately, and the first component and the second component are mixed and filled when the pouring is required. The first component and the second component are separated and stored, so that the components are convenient to store and transport.

In some embodiments, the first component has a viscosity of 800cps to 1500cps and a density of 1.0g/cm ³ -1.3g/cm ³ The method comprises the steps of carrying out a first treatment on the surface of the The viscosity of the second component is 250cps to 800cps, and the density of the second component is 1.0g/cm ³ -1.3g/cm ³ 。

As an example, the viscosity of the first component may be 800cps, 850cps, 900cps, 950cps, 1000cps, 1050cps, 1150cps, 1250cps, 1300cps, 1350cps, 1400cps, 1450cps, or 1500cps.

As an example, the first component may have a density of 1.0g/cm ³ 、1.05g/cm ³ 、1.1g/cm ³ 、1.15g/cm ³ 、1.2g/cm ³ 、1.25g/cm ³ Or 1.3g/cm ³ 。

As an example, the viscosity of the second component may be 250cps, 300cps, 350cps, 400cps, 450cps, 500cps, 550cps, 600cps, 650cps, 700cps, 750cps, or 800cps.

As an example, the second component may have a density of 1.0g/cm ³ 、1.05g/cm ³ 、1.1g/cm ³ 、1.15g/cm ³ 、1.2g/cm ³ 、1.25g/cm ³ Or 1.3g/cm ³ 。

The term "viscosity" as used herein is intended to mean the meaning known in the art and can be measured using instruments and methods known in the art. By way of example, the viscosity can be found by reference to GB/T2794, using a 14# rotor, tested at 100 rpm.

In some embodiments, the first component in the first pouring sealant has a mass of m _1-1 The mass of the second component in the first pouring sealant is m _1-2 ，m _1-1 :m _1-2 Is (100:70) - (100:90).

As an example, m _1-1 :m _1-2 May be (100:70), (100:72), (100:75), (100:78), (100:80), (100:82), (100:85), (100:87) or (100:90).

In some embodiments, the first component meets at least one of the following conditions: the resin includes at least one of polyether polyol and polyester polyol; the number average molecular weight of the resin is 5000-10000; the catalyst comprises at least one of tertiary amine catalyst and organotin catalyst; the foaming agent comprises water.

As an example, the tertiary amine catalyst may include triethylenediamine; the organotin-based catalyst may include dibutyltin dilaurate.

When water is mixed with isocyanate groups, a reaction occurs to produce carbon dioxide gas, i.e., foaming is performed; when the polyol resin is mixed with isocyanate groups, a crosslinking reaction occurs to produce polyurethane-like materials. That is, the isocyanate substance can react with water to generate gas, and can also react with resin in a crosslinking way to generate polyurethane. The reaction rate of the crosslinking reaction can be accelerated by adding the catalyst, and the yield per unit time is improved.

In some embodiments, the first component further comprises 20 to 30 parts by weight of a flame retardant, 1 to 3 parts by weight of a foam stabilizer, 0.2 to 0.6 parts by weight of a filler; optionally, the flame retardant comprises a phosphate flame retardant; optionally, the foam stabilizer comprises a silicone-based foam stabilizer; optionally, the filler comprises silica.

As an example, the phosphate flame retardant may include a triphosphate; the silicone-based foam stabilizer may include a polyether modified polysiloxane.

The flame retardant property of the first pouring sealant can be improved through the addition of the flame retardant; the foam structure can be stabilized and the foaming quality can be improved by adding the foam stabilizer; the structural strength of the first pouring sealant can be improved through the addition of the filler.

In some embodiments, the isocyanate-based cross-linking agent includes at least one of diphenylmethane diisocyanate and polymethylene polyphenyl isocyanate.

In some embodiments, since the isocyanate-based cross-linking agent is relatively sensitive to moisture, the moisture content of the second component itself, as well as the humidity of the storage environment, needs to be low to reduce the reaction of the isocyanate with moisture during storage.

In some embodiments, the first pouring sealant satisfies at least one of the following conditions: the free foaming density of the first pouring sealant is 0.2g/cm ³ -0.3g/cm ³ The method comprises the steps of carrying out a first treatment on the surface of the The priming time of the first pouring sealant is 2min-3min; the surface drying time of the first pouring sealant is 5-10 min.

When the first pouring sealant meets the conditions, the foaming process of the first pouring sealant is convenient to control.

The free foaming density refers to the density after foaming in the absence of other unwanted confined spaces, for example, by placing the glue to be foamed in a cup.

The term "free cell density" as used herein is intended to mean a value known in the art and can be measured using equipment and methods known in the art. As an example, the free foaming density may be tested with reference to the drainage measured density. In particular, the following method can be seen:

(1) Controlling the material temperature (25+/-1 ℃), mixing 100g of a first component and a second component with the corresponding mass (according to the required mass ratio), stirring for 30s at the rotating speed of 2500rpm, foaming, cutting into glue blocks with the side length not less than 5cm, and measuring the density by adopting a soaking method.

(2) The immersion method comprises the following measuring steps: weigh mass m of cut glue piece ₁ The method comprises the steps of carrying out a first treatment on the surface of the Placing the water container in an electronic scale and setting the water container to zero; immersing the rubber block in water completely, keeping the distance between the rubber block and the liquid level less than or equal to 5mm, and recording the digital display weight m at the moment ₂ The method comprises the steps of carrying out a first treatment on the surface of the Glue block density ρ=m ₁ /m ₂ 。

S200: injecting a second pouring sealant from the opening of the upper box body

In some embodiments, a second pouring sealant is injected from the opening of the upper box body in the step to obtain a second pouring sealant layer, and then the second pouring sealant and the first pouring sealant together fill the closed space in the battery pack.

In some embodiments, an opening may be provided in the upper case in advance, the opening in the upper case is sealed in the foaming process of the first pouring sealant, after the foaming of the first pouring sealant is completed, the opening is opened to release the pressure of the gas generated in the foaming process of the first pouring sealant, and then the second pouring sealant is injected into the battery pack.

In some embodiments, the second pouring sealant is obtained by mixing a third component and a fourth component, the third component comprising 60 parts by weight to 80 parts by weight of resin, 0.1 parts by weight to 0.5 parts by weight of catalyst; the fourth component comprises 40-60 parts by weight of isocyanate cross-linking agent, 15-30 parts by weight of filler and 10-30 parts by weight of flame retardant. Therefore, the third component and the fourth component can be stored separately, and the storage and the transportation are convenient.

As an example, the weight part of resin in the third component may be 60, 65, 70, 75 or 80; the weight parts of catalyst in the third component may be 0.1, 0.2, 0.3, 0.4 or 0.5.

Because the second pouring sealant is polyurethane pouring sealant, polyurethane can be generated by mixing resin and isocyanate cross-linking agent at normal temperature, the third component and the fourth component are required to be stored separately, and the third component and the fourth component are mixed and filled when the pouring is required. The third component and the fourth component are stored separately, so that the components can be stored and transported conveniently.

As an example, the viscosity of the third component may be 2000cps, 2050cps, 2100cps, 2150cps, 2200cps, 2250cps, 2300cps, 2350cps, 2400cps, 2450cps, or 2500cps.

As an example, the density of the third component may be 0.7g/cm ³ 、0.72g/cm ³ 、0.75g/cm ³ 、0.77g/cm ³ Or 0.8g/cm ³ 。

As an example, the viscosity of the fourth component may be 2500cps, 2550cps, 2600cps, 2650cps, 2700cps, 2750cps, 2830cps, 2850cps, 2900cps, 2950cps, or 3000cps.

As an example, the density of the fourth component may be 0.7g/cm ³ 、0.72g/cm ³ 、0.75g/cm ³ 、0.77g/cm ³ Or 0.8g/cm ³ 。

In some embodiments, the third component in the second pouring sealant has a mass of m _2-1 The mass of the fourth component in the second pouring sealant is m _2-2 ，m _2-1 :m _2-2 Are (90:100) - (110:100).

As an example, m _2-1 :m _2-2 May be (90:100), (92:100), (95:100), (98:100), (100:100), (103:100), (105:100), (107:100) or (110:100).

In some embodiments, the third component meets at least one of the following conditions: the resin includes at least one of polyether polyol and polyester polyol; the number average molecular weight of the resin is 5000-15000; the catalyst comprises an organotin catalyst.

As an example, the organotin-based catalyst may include dibutyltin dilaurate.

When the polyol resin is mixed with isocyanate groups, a crosslinking reaction occurs to produce polyurethane-like materials. The reaction rate of the crosslinking reaction can be accelerated by adding the catalyst, and the yield per unit time is improved.

In some embodiments, the third component further comprises: 10-30 parts by weight of flame retardant and 10-30 parts by weight of filler; optionally, the flame retardant comprises a phosphate flame retardant; optionally, the filler comprises hollow glass microspheres.

As an example, the phosphate flame retardant may include a triphosphate.

The flame retardant property of the second pouring sealant can be improved through the addition of the flame retardant, and the structural strength of the second pouring sealant can be improved through the addition of the filler.

In some embodiments, the fourth component satisfies at least one of the following conditions: the isocyanate cross-linking agent comprises aliphatic isocyanate; the filler comprises hollow glass beads; the flame retardant includes phosphate flame retardants.

The flame retardant property of the second pouring sealant can be improved through the addition of the flame retardant; the structural strength of the second pouring sealant can be improved by adding the filler.

In some embodiments, the glue outlet speed and time of the glue injecting device can be used for controlling the glue outlet amount of the pouring sealant, and the foaming time of the first pouring sealant can be controlled by adjusting the proportion of the first component and the second component.

It can be understood that the specific glue consumption and foaming time need to be adjusted according to the requirements of different battery pack sizes, structural designs and performances, and those skilled in the art can select and adjust according to practical situations in the application process.

It will be appreciated by those skilled in the art that in the above-described method of the specific embodiment, the written order of steps is not meant to imply a strict order of execution but rather should be construed according to the function and possibly inherent logic of the steps.

In a third aspect of the present application, an electrical device is provided, where the electrical device includes the battery pack described above, or a battery pack prepared by the method described above. Thus, the power utilization device includes all the features and advantages of the foregoing battery pack and the method for preparing the battery pack, which are not described in detail herein.

The battery pack may be used as a power source for the electrical device or as an energy storage unit for the electrical device. The electric device may include, but is not limited to, electric vehicles (e.g., electric only vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, watercraft and satellites, energy storage systems, and the like.

Fig. 7 is an electrical device as an example. The electric device is a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle and the like. In order to meet the requirements of the power utilization device for high power and high energy density of the battery, a battery pack can be adopted as a power supply device.

The following description of the present application is made by way of specific examples, which are given for illustration only and should not be construed as limiting the scope of the present application. The examples are not to be construed as limiting the specific techniques or conditions described in the literature in this field or as per the specifications of the product. The reagents or apparatus used were conventional products commercially available without the manufacturer's attention.

The composition (in parts by weight) and the ratio of the first component and the second component of the first pouring sealant in examples 1 to 3 are shown in Table 1, wherein the polyether polyol in the resin has a number average molecular weight of 5000, a CAS number of 9003-11-9, the polyester polyol in the resin has a number average molecular weight of 6000, and a CAS number of 53637-25-5; the composition (all in parts by weight) and the proportion of the third component and the fourth component of the second pouring sealant are shown in table 2, wherein the number average molecular weight of polyether polyol in the resin is 5000, the CAS number is 9003-11-9, the number average molecular weight of polyester polyol in the resin is 6000, and the CAS number is 53637-25-5. And the first pouring sealant and the second pouring sealant are tested as follows:

1. density of pouring sealant: the test is carried out with reference to GB/T13354, see in particular the following method:

The experimental steps are as follows:

(2) The weighing cup is washed with a volatile solvent and dried.

The calculation method comprises the following steps:

2. Adhesive strength of pouring sealant: the test is carried out with reference to GB/T7124, see in particular the following method:

3. Coefficient of thermal conductivity of pouring sealant: the test is carried out with reference to ISO22007-2, in particular, see the following method:

4. Modulus of elasticity of pouring sealant: with reference to IPC-TM-650 2.4.24.4, dma was tested, see in particular the following method:

(4) And recording a test result.

5. Flame retardant rating of pouring sealant: the test was performed with reference to the UL94-V standard. The flame retardant properties increase in sequence with flame retardant grades V2, V1, V0, see in particular the following method:

the vertical burning, the testing steps include: the flame height is 20 plus or minus 1mm, the Bunsen burner is arranged at the right central position below the sample, the mouth of the Bunsen burner is 10 plus or minus 1mm away from the bottom end of the sample, the ignition time is 10 plus or minus 0.5s, the Bunsen burner is removed at least 150mm at a speed of 300mm/sec after the ignition time is 10 plus or minus 0.5s, and the after-flame time t is recorded at the same time ₁ When the after flame is stopped, the after flame is immediately ignited for 10+/-0.5 s, and after 10+/-0.5 s, the after flame is ignited, the after flame is removed from the Bunsen burner at a speed of 300mm/sec for at least 150mm, and the after flame time t is recorded ₂ And after flame time t ₃ . T recorded in the test procedure ₁ ，t ₂ ，t ₃ And (3) carrying out flame retardant grade classification according to the evaluation standards of the following table.

Flame retardant rating evaluation criterion

6. Free foaming density of the first pouring sealant: the test was performed with reference to the drainage method for measuring density, see in particular the following method:

TABLE 1

TABLE 2

Example 1

Preparation of a battery pack: uniformly mixing a first component and a second component to obtain a first pouring sealant to be foamed, pouring and sealing the whole battery cell and the battery module by the first pouring sealant to be foamed, and controlling the glue injection amount and the foaming time to enable the first pouring sealant to be foamed to the height of a battery cell pole so as to obtain a first pouring sealant; after the surface of the first encapsulating layer is dried, uniformly mixing the third component and the fourth component to obtain a second encapsulating adhesive, encapsulating the battery monomer and a gap between the battery module and the upper box body from the opening of the upper box body by the second encapsulating adhesive to obtain a battery pack, wherein the structure of the battery pack is shown in fig. 1. In example 1, the volume ratio of the first pouring sealant to the second pouring sealant was 5:2.

The preparation of the battery packs in example 2 and example 3 was consistent with example 1.

In comparative example 1, the battery pack was potted using only the first potting adhesive of example 3, including potting the gaps between the entire battery cells and the battery modules, and the gaps between the battery cells and the battery modules and the upper case; the battery pack was potted using only the second potting compound of example 3 in comparative example 2, including potting the entire gap between the battery cells and the battery modules, and the gap between the battery cells and the battery modules and the upper case.

The battery packs of examples 1 to 3 and comparative examples 1 to 2 were tested, and the battery pack safety performance test method was referred to GB/T38031-2020. Mass energy density of battery pack = energy released by first discharge of battery pack/total mass of battery pack. The test results are shown in Table 5.

The battery pack safety performance testing method comprises the following steps: the test object is a battery pack. The test subjects were subjected to a half sine shock wave defined in table 3 below, 6 times each in the ±z direction, and a total of 12 times. The half sine shock wave maximum and minimum tolerance ranges are shown in tables 4 and 9 below.

The interval between two adjacent impacts is such that the responses of the two impacts on the test sample do not affect each other, and should generally be no less than 5 times the impact pulse duration. After completion of the above test procedure, it was observed at the test ambient temperature for 2 hours.

TABLE 3 Table 3

TABLE 4 Table 4

The quality energy density testing method of the battery pack comprises the following steps: tool clamp: 450V/200A test cabinet, computer, fluke multimeter, vehicle spin test software; the testing steps comprise: (1) Standing for 30min, and observing whether the information such as the voltage, the temperature and the like of the battery pack are normal; (2) discharging the constant current 1C until the voltage of the battery cell is less than or equal to 3V); (3) resting for 30min; (4) Constant current 0.5C is charged until the voltage of the battery cell is more than or equal to 4.15V; (5) resting for 30min; (6) discharging the constant current 1C until the voltage of the battery cell is less than or equal to 3V); (7) resting for 30min; (8) At the end, the mass energy density of the battery pack=discharge capacity (6 th step capacity) ×battery pack nominal voltage/battery pack overall mass in the unit ah×v/kg=wh/kg.

TABLE 5

The test results show that: the battery pack is combined and encapsulated by the first pouring sealant and the second pouring sealant, so that the high-quality energy density of the battery pack is met, the high structural strength requirement of the battery pack can be met, the vibration impact test of the battery pack can be realized, and the thermal runaway spontaneous combustion risk of the battery pack can be reduced due to the flame-retardant and heat-insulating properties of the body of the two pouring sealants.

Comparative example 1 only adopted the first pouring sealant of foaming to encapsulate, and the overall quality of battery package is lighter, can satisfy battery package high quality energy density demand, but has the problem of bonding strength inadequately because of first pouring sealant, leads to it unable to pass battery package security performance test.

Comparative example 2 only used a non-foaming second potting compound for potting, although having a better adhesive strength, the density of the second potting compound was higher than that of the first potting compound, and therefore the overall mass of the battery was heavier, resulting in an inability to sufficiently meet the high-quality energy density requirements.

The present application is not limited to the above embodiment. The above embodiments are merely examples, and embodiments having substantially the same configuration and the same effects as those of the technical idea within the scope of the present application are included in the technical scope of the present application. Further, various modifications that can be made to the embodiments and other modes of combining some of the constituent elements in the embodiments, which are conceivable to those skilled in the art, are also included in the scope of the present application within the scope not departing from the gist of the present application.

Claims

1. A battery pack, comprising:

the battery box comprises an upper box body and a lower box body, wherein the upper box body is covered on the lower box body and forms a closed space;

the first encapsulating layer is positioned on one side, close to the lower box body, of the closed space, and comprises a first pouring sealant and a plurality of battery monomers, wherein the first pouring sealant is positioned between adjacent battery monomers and covers the surfaces of the battery monomers;

The second encapsulating layer is positioned at one side, close to the upper box body, of the closed space, and comprises second pouring sealant;

the density of the first pouring sealant is smaller than that of the second pouring sealant, the bonding strength of the second pouring sealant is larger than that of the first pouring sealant, the battery unit comprises a shell and a top cover assembly, a pole is arranged on the top cover assembly, and the first pouring sealant at least covers the side wall of the pole.

2. The battery pack of claim 1, wherein the volume of the first potting adhesive is greater than the volume of the second potting adhesive within the enclosed space.

3. The battery pack of claim 2, wherein the volume of the first potting adhesive in the enclosed space is V ₁ The volume of the second pouring sealant in the closed space is V ₂ ，V ₁ ：V ₂ Are (5:2) - (3:2).

4. The battery pack of claim 1, wherein the first potting adhesive has a density of 0.3g/cm ³ -0.4g/cm ³ The density of the second pouring sealant is 0.7g/cm ³ -0.8g/cm ³ 。

5. The battery pack according to claim 1, wherein the adhesive strength of the first potting adhesive is 2MPa to 3MPa and the adhesive strength of the second potting adhesive is 8MPa to 10MPa.

6. The battery pack of claim 1, wherein the first potting adhesive satisfies at least one of the following conditions:

the heat conductivity coefficient of the first pouring sealant is 0.01W/(m.K) -0.03W/(m.K);

the elastic modulus of the first pouring sealant at 25 ℃ is 150-200 MPa;

the flame retardant grade of the first pouring sealant is V0;

the first pouring sealant comprises polyurethane substances.

7. The battery pack of claim 1, wherein the second potting adhesive satisfies at least one of the following conditions:

the heat conductivity coefficient of the second pouring sealant is 0.2W/(m.K) -0.3W/(m.K);

the elastic modulus of the second pouring sealant at 25 ℃ is 250MPa-300MPa;

the flame retardant grade of the second pouring sealant is V0;

the second pouring sealant comprises polyurethane substances.

8. The battery pack of claim 1, wherein the battery cells are cylindrical battery cells.

9. The battery pack according to claim 1, wherein the first potting adhesive is obtained by mixing a first component and a second component, the first component comprising a resin and a foaming agent; the second component comprises an isocyanate cross-linking agent, and the resin reacts with the isocyanate cross-linking agent to generate polyurethane substances.

10. The battery pack according to claim 1, wherein the second potting adhesive is obtained by mixing a third component and a fourth component, the third component comprising a resin; the fourth component comprises an isocyanate cross-linking agent, and the resin reacts with the isocyanate cross-linking agent to generate polyurethane substances.

11. A method of making the battery pack of any one of claims 1-10, comprising:

placing a battery monomer in a lower box body, injecting a first pouring sealant to be foamed into the lower box body, and covering an upper box body on the lower box body to form a closed space so that the first pouring sealant to be foamed foams in the closed space to obtain a first pouring sealant layer;

and injecting a second pouring sealant from the opening of the upper box body to obtain a second pouring sealant layer so as to fill the closed space.

12. The method of claim 11, wherein the first pouring sealant is obtained by mixing a first component and a second component, the first component comprising 50 to 70 parts by weight of resin, 1 to 3 parts by weight of catalyst, 5 to 10 parts by weight of foaming agent; the second component includes an isocyanate-based crosslinker.

13. The method of claim 12, wherein the first component has a viscosity of 800cps to 1500cps and a density of 1.0g/cm ³ -1.3g/cm ³ The method comprises the steps of carrying out a first treatment on the surface of the The viscosity of the second component is 250cps to 800cps, and the density of the second component is 1.0g/cm ³ -1.3g/cm ³ 。

14. The method of claim 12, wherein the mass of the first component in the first casting glue is m _1-1 The mass of the second component in the first pouring sealant is m _1-2 ，m _1-1 :m _1-2 Is (100:70) - (100:90).

15. The method of any one of claims 12-14, wherein the first component meets at least one of the following conditions:

the resin includes at least one of a polyether polyol and a polyester polyol;

the number average molecular weight of the resin is 5000-10000;

the catalyst comprises at least one of a tertiary amine catalyst and an organotin catalyst;

the foaming agent comprises water.

16. The method according to any one of claims 12 to 14, wherein the isocyanate-based cross-linking agent comprises at least one of diphenylmethane diisocyanate and polymethylene polyphenyl isocyanate.

17. The method of claim 11, wherein the second pouring sealant is obtained by mixing a third component and a fourth component, the third component comprising 60 parts by weight to 80 parts by weight of resin, 0.1 parts by weight to 0.5 parts by weight of catalyst; the fourth component comprises 40-60 parts by weight of isocyanate cross-linking agent, 15-30 parts by weight of filler and 10-30 parts by weight of flame retardant.

18. The method of claim 17, wherein the third component has a viscosity of 2000cps to 2500cps and a density of 0.7g/cm ³ -0.8g/cm ³ The method comprises the steps of carrying out a first treatment on the surface of the The viscosity of the fourth component is 2500cps-3000cps, and the density of the fourth component is 0.7g/cm ³ -0.8g/cm ³ 。

19. The method of claim 17 or 18, wherein the mass of the third component in the second pouring sealant is m _2-1 The mass of the fourth component in the second pouring sealant is m _2-2 ，m _2-1 :m _2-2 Are (90:100) - (110:100).

20. The method of claim 17 or 18, wherein the third component meets at least one of the following conditions:

the resin includes at least one of a polyether polyol and a polyester polyol;

the number average molecular weight of the resin is 5000-15000;

the catalyst comprises an organotin catalyst.

21. The method of claim 17 or 18, wherein the fourth component meets at least one of the following conditions:

the isocyanate cross-linking agent comprises aliphatic isocyanate;

the filler comprises hollow glass beads;

the flame retardant comprises a phosphate flame retardant.

22. An electrical device comprising the battery pack of any one of claims 1-10 or prepared by the method of any one of claims 11-21.