WO2021129163A1

WO2021129163A1 - Battery module foam selection method and battery module

Info

Publication number: WO2021129163A1
Application number: PCT/CN2020/126082
Authority: WO
Inventors: 李峥; 冯玉川; 何泓材; 陈凯; 杨帆; 南策文
Original assignee: 苏州清陶新能源科技有限公司
Priority date: 2019-12-27
Filing date: 2020-11-03
Publication date: 2021-07-01
Also published as: CN111129386B; CN111129386A

Abstract

Provied are a battery module foam selection method and a battery module. The battery module comprises a battery cell (12) and a foam, wherein the foam, the battery cell (12) and the module meet the following dimension relationship: y×(1-x%)=A; y×(z %-X%)=φ; where A is the size of the pre-tightened foam, y is the thickness of the foam, x% is a pre-tightened foam compression amount, z% is the total foam compression amount, and φ is a expansion space of the battery cell (12).

Description

Method for selecting battery module foam and battery module

Technical field

This application belongs to the technical field of new energy, and relates to a method for selecting battery module foam and a battery module.

Background technique

As a kind of power battery, the soft-pack battery is widely used in electric vehicles after being integrated into the battery system in the form of a battery module; in the actual use of the soft-pack battery, the battery performance will continue to decay and be accompanied by volume expansion.

Studies have shown that a certain pre-tightening force must be applied to the soft-pack battery during application. At the same time, a certain amount of cell expansion space must be reserved (a certain pre-tightening force is applied to the soft-pack battery at the beginning of its life. , Power) attenuation slowly, and the expansion during the life cycle will be slowed); in order to better exert the performance of the battery cell, the industry’s usual practice is to install foam between the cells during the module design, and pass through and out of the module. The frame applies a certain pre-tightening force to the battery core and reserves a certain expansion space for the battery core.

At present, when selecting foams, industry technicians generally choose according to some of the physical and chemical properties of the foam, the size of the module product, and the product development experience; however, due to the wide variety of foams and the long verification period (generally in Only at the end of the life of the battery and the module can be determined whether the foam selection is appropriate).

Therefore, the unscientific and unsystematic method of foam selection has greatly affected the efficiency of battery module design and product reliability; in the prior art, the pre-tightening force of the soft pack battery, the expansion space of the battery cell, and the selection of foam are greatly affected. There is very little research on the type method, and no published documents or patents have introduced a scientific method of foam selection.

CN110336098A discloses a battery module with a heating film, which includes a heating film system assembly and a battery cell module. The heating film system assembly includes a PI heating film body, an isolation foam and a bottom support foam. The PI The heating film body includes a PI film and a resistance wire, the PI film is provided with hollow holes, and the hollow holes separate the PI film into at least two module arrangement areas, and the adjacent module arrangement areas pass through the hollow holes The PI membranes on both sides are connected, the resistance wire is wrapped inside the module layout area, the isolation foam is respectively arranged on the PI membrane on both sides of the hollow hole, and the bottom support foam is arranged on the PI heating membrane body Below, the thermally conductive bottom surface of the battery cell module is pressed on the module layout area.

CN206742405U discloses a box-mounted battery module, which includes a module box, a battery cell, a foam and an insulating board. Along the thickness direction of the battery, a plurality of battery cells and a plurality of foams are bonded to each other and clamped in the insulation Between the plates, the insulating plate assembles the multiple batteries and multiple foams of the battery cells to form a battery module, and the battery module is squeezed and installed in the module box; each battery cell passes in the longitudinal direction The thermal paste is in contact with the module box.

CN206179944U discloses a battery module, which includes a plurality of single batteries, a plurality of fixed bases and adhesives; each fixed base includes a plurality of base units, and each base unit is provided with a corresponding one The accommodating cavity of the single battery; the plurality of base units of the fixed base are arranged in multiple rows in a centrally symmetrical manner, and the number of the base units in each row is the same, and all of the two adjacent rows The connecting line of the central axis of the base unit is in a zigzag shape; the adhesive includes foam and a cross-linking agent, the foam includes a plurality of uniformly distributed cells; the foam is rectangular and includes a pair Parallel long sides, the crosslinking agent is located on the two sides of the foam close to a pair of long sides; the two adjacent fixing bases are fixed together by the adhesive.

CN207490073U discloses a liquid cooling and heating unit for a power battery module, comprising a water-cooling plate and a support frame that are detachably installed together. The water-cooling plate is pasted with a thermally conductive silicone pad on the side away from the support frame, and the water-cooling plate is pasted on the side close to the support frame Thermal insulation foam and elastic support foam.

CN208690361U discloses a battery module with an expansion and slow-release structure, comprising a rectangular parallelepiped frame and electric cores placed in the frame. The electric cores are plate-shaped. There are several electric cores arranged side by side, two adjacent to each other. A plate-shaped expanded flame-retardant foam is arranged between the cells, and the side of the cell is close to the expanded flame-retardant foam; there is also a buffer between the outer sides of the two outermost cells and the side of the frame spring.

Although the above applications all use foam in the battery module, they do not mention effective foam selection methods, which makes the selection of foam without scientific basis and methods during module development.

Summary of the invention

The purpose of this application is to provide a battery module foam selection method and battery module. The battery module foam selection method provided in this application can solve the problems of battery pre-tightening force and cell expansion space in the module, improve the design efficiency of the module and product reliability, and ensure the structural reliability of the module during the whole life cycle.

To achieve this goal, this application adopts the following technical solutions:

In a first aspect, the present application provides a method for designing a battery module, which includes a battery cell and a foam, and the foam, the battery and the module satisfy the following dimensional relationship:

y×(1-x%)=A;

y×(z%-x%)=φ;

Among them, A is the size of the foam pre-tightened, y is the thickness of the foam, x% is the compression of the foam, z% is the total compression of the foam, and φ is the expansion space of the cell.

According to the size relationship defined by this equation, when the width of the module and the thickness of the battery are fixed, the specifications of the foam can be determined according to the required pre-tightening force of the battery, the expansion space of the battery, and the foam pressure curve.

In the same way, technicians can determine the thickness of the battery cell and guide the development of the battery cell according to the required pre-tightening force of the battery cell and the expansion space of the battery cell, the foam pressure curve, and the thickness of the foam when the module width is fixed. design.

Furthermore, when the cell size is determined, the pre-tightening force and the cell expansion space are determined, the size of the module can be determined according to the foam thickness and the foam pressure curve to guide the development and design of the module.

In the second aspect, as a particularly important part of this application, this application provides a method for selecting battery module foam. The method includes the following steps:

(1) Measure cell pre-tightening force F and cell expansion space φ;

(2) Using the cell pre-tightening force F and the foam pressure deformation characteristics described in step (1) to determine the foam pre-tightening compression amount x%;

(3) Obtain the pre-tightened size A of the foam, and use the equation: y×(1-x%)=A to calculate the thickness of the foam y;

(4) Using the equation: y×(z%-x%)=φ, calculate the total foam compression z%, according to step (2) the foam pre-tightening compression x%, step (3) the foam The thickness of the cotton y and the total compression of the foam z% are used to select the foam.

In the method provided in this application, the battery module may be a soft pack battery module.

In the method provided in this application, the method for obtaining key parameters involved in the foam selection process (foam preload compression x%, foam thickness dimension y, and foam total compression z%) is given; These parameters can scientifically quantify the foam selection plan, greatly reduce the foam selection process, and improve the efficiency of module design and product reliability. In the method provided in this application, a suitable foam can be selected through the final compression x% of the foam, the thickness dimension y of the foam, and the total compression z% of the foam. The pre-tensioning requirements at the initial stage of the core and the expansion requirements during the lifespan ensure the reliability of the module structure.

The selection method provided in this application can select materials that meet the corresponding conditions from the database based on the parameters determined above when the major types of materials are determined; this method avoids the technical personnel from being unscientific in the foam selection Guidance basis and the dilemma of a large number of experiments.

The following are optional technical solutions for this application, but not as a limitation to the technical solutions provided by this application. Through the following optional technical solutions, the technical objectives and beneficial effects of this application can be better achieved and realized.

As an optional technical solution of this application, the foam includes any one or at least two of polyurethane (PU) foam, ethylene-vinyl acetate (EVA) foam or neoprene (CR) foam The combination of, optional polyurethane foam.

Polyurethane (PU) foam can maintain sufficient elastic recovery ability under long-term compression, and is suitable for use in soft-pack battery modules.

As an optional technical solution of the present application, the cell pre-tightening force F and the cell expansion space φ in step (1) are obtained by a cell pre-tensioning expansion detection device.

As an optional technical solution of the present application, the pressure deformation characteristics of the foam in step (2) are obtained by measuring the strain of the foam under different stress conditions and fitting the result to a curve or characteristic equation simulation.

In this application, the fitting method may use Matlab engineering software, and the fitting method is a conventional technique in this field, and will not be repeated here.

As an optional technical solution of the present application, the size A of the foam pre-tensioned in step (3) is the difference between the width of the battery module and the total width occupied by other parts.

In this application, the total width occupied by the other components refers to the total length of the other components in the battery module in the width direction of the battery module. For example, if the rectangular parallelepiped cells are arranged upright in the battery module, that is, the surface of the rectangular parallelepiped cell with the smallest area is in contact with the bottom surface of the battery module, then the thickness of the cell is used as its share in the width direction of the battery module. length.

As an optional technical solution of the present application, the total width occupied by the other components includes the total thickness of the battery core.

In this case, the rectangular parallelepiped cells are arranged in the battery module.

As an optional technical solution of the present application, the total width occupied by the other components also includes the width of any one or at least two of the battery core, the heat insulating plate, the heat conducting plate, the frame, or the glue. There are several components in the battery module to be tested that occupy the width space, and the width occupied by these components is calculated into the total width occupied by the other components. The total width occupied by the other components is not limited to the above components. If there are other similar components in the battery module that need to occupy the width space, they should also be included in the calculation. Here, the glue refers to adhesive glue.

As a further optional technical solution of the battery module foam selection method described in this application, the method includes the following steps:

(1) Measure cell pre-tightening force F and cell expansion space φ;

(4) Using the equation: y×(z%-x%)=φ, calculate the total foam compression z%, according to step (2) the foam pre-tightening compression x%, step (3) the foam The thickness of the cotton y and the total compression of the foam z%, select the foam;

Wherein, the cell pre-tightening force F and the cell expansion space φ are obtained by using a cell pre-tightening expansion detection device;

The pressure deformation characteristic of the foam is obtained by measuring the strain of the foam under different stress conditions, and fitting the result to a curve or characteristic equation;

In this application, A is used to indicate the size of the foam after pre-tensioning. In an embodiment, the difference of the width of the battery module minus the total width occupied by other parts can be used as the size A after pre-tensioning of the foam . The total width occupied by the other components includes the total thickness of the battery core and the width of the heat insulation board, the heat conducting board, the frame or the glue.

In a third aspect, the present application provides a battery module, the battery module includes a battery cell and foam, and the foam is selected according to the battery module foam selection method described in the first aspect.

The battery module obtained by using the method provided in the application for foam selection solves the problems of battery pre-tightening force and cell expansion space in the module, improves module design efficiency and product reliability, and ensures that the module is in the full life cycle Reliable structure.

As an optional technical solution of the present application, the battery module is a soft pack battery module.

In a fourth aspect, the present application provides a battery module, including a battery cell and foam, and the foam and the module satisfy the following dimensional relationship:

y×(1-x%)=A;

y×(z%-x%)=φ;

Compared with the prior art, this application has the following beneficial effects:

(1) The battery module foam selection method provided in this application as a technical selection plan can guide the battery module foam selection, and the foam selection plan can be scientifically quantified to optimize the foam selection This type of process improves module design efficiency and product reliability, and solves the problems of battery pre-tightening force and cell expansion space in the module.

(2) The battery module using the battery module foam selection method provided in this application for foam selection has better electrical performance, especially the capacity and power of the module attenuate more slowly, and the increase in internal resistance is slower; The module structure is more stable and reliable, and will not cause failure due to deformation of the module frame due to the expansion of the battery core.

Description of the drawings

FIG. 1 is a schematic diagram of the structure of the cell pretension and expansion detection device for measuring the cell pretension force F and the cell expansion space φ in Embodiment 1;

2 is a front view of the battery pretension and expansion detection device used to measure the pretension force F and the expansion space φ of the battery in Embodiment 1;

Among them, 1-screw, 2-top plate, 3-pressure plate, 4-elastic component, 5-displacement sensor, 6-upper splint, 7-lower splint, 8-base plate, 9-support rod, 10-buffer layer, 11-pressure sensor, 12-cell;

Figure 3 is a PU foam stress-strain fitting curve used to calculate the foam preload compression x% in Example 1.

Detailed ways

In order to better explain the application and facilitate the understanding of the technical solutions of the application, the application will be further described in detail below. However, the following embodiments are only simple examples of this application, and do not represent or limit the scope of protection of the rights of this application. The scope of protection of this application is subject to the claims.

The following are typical but non-limiting examples of the application:

Example 1

In this embodiment, the foam selection is performed according to the following method:

This embodiment uses the VDA355 module, the module size is: 355×151×108.5mm, the cell size is: 310×102×11mm; the module width: 151mm, the thickness of all cells: 11×12=132mm, other zero The sum of the thickness of the parts (heat insulation board and glue): 9mm.

(1) Use the cell pretension and expansion detection device shown in Figure 1 and Figure 2 to test the cell pretension force F and the cell expansion space φ. It is measured that the best pre-tightening force F of the battery core is 30KPa and the expansion space of the battery core is 5%.

The battery pre-tensioning expansion detection device includes a screw 1, a pressure plate 3, an elastic component 4, an upper splint 6, a lower splint 7 and a pressure sensor 11 from top to bottom. The upper splint 6 is provided with a displacement sensor on the edge 5; The bottom of the screw 1 is in contact with the pressure plate 3 and is set in the middle position of the pressure plate 3. There are at least four elastic components 4, which are evenly arranged between the pressure plate 3 and the upper clamping plate 6, so The upper splint 6 and the lower splint 7 are arranged in parallel and spaced apart, and there are at least four pressure sensors 11, which are evenly arranged under the lower splint 7. The screw 1 is a mechanical screw and includes a rotating part and a pressing part. The rotating part is arranged at the top of the pressing part and is perpendicular to the pressing part. The elastic component 4 includes a spring, and the number of the spring is six. The number of the displacement sensor 5 is four, the displacement sensor 5 is not in contact with the pressure plate 3, and the displacement sensor 5 is a push rod type displacement sensor. The surfaces of the upper splint 6 and the lower splint 7 are pasted with a polytetrafluoroethylene layer, and the lower surface of the upper splint 6 and the upper surface of the lower splint 7 are further provided with a buffer layer 10, which is a rubber buffer layer , The thickness of the two buffer layers 10 are both 5 mm. The device also includes a top plate 2 and a bottom plate 8, the top plate 2 is located above the pressure plate 3, the screw 1 passes through the top plate 2, the bottom plate 8 is located below the lower splint 7, and the pressure sensor 11 is arranged on the bottom plate 8. on. A support rod 9 is arranged between the top plate 2 and the bottom plate 8, and the support rod 9 is vertically arranged on the edges of the top plate 2 and the bottom plate 8, and the number of the support rods is four. The support rod 9 passes through the upper splint 6 and the lower splint 7, the upper splint 6 can move along the support rod 9, and the lower splint 7 is fixed. The battery core 12 has a size of 310×102×11 mm, and is placed between the buffer layer 10 on the upper splint 6 and the lower splint 7.

When using the battery cell pretensioning expansion detection device to detect battery cells, place the bar-shaped cell between the buffer layers of the upper and lower splints, adjust the position of the upper splint so that the buffer layer on the upper splint is in contact with the battery core, and rotate The mechanical screw applies pressure to the pressure plate, and then transmits it to the upper splint through the spring; tests the cell, records the readings of the displacement sensors and pressure sensors, and obtains the changes in cell pressure and thickness.

(2) Fit the stress-strain curve according to the stress-strain data of PU foam. The curve is shown in Figure 3 (the ordinate is the stress and the abscissa is the strain). According to the curve, it can be determined that when the stress is 30KPa (0.03MPa) When, the foam pre-tightening compression amount x% = 15%.

(3) By subtracting the sum of the thickness of all the battery cells and the thickness of other parts except the battery from the module width, the pre-tensioned size A=(151-132-9)=10mm is obtained. Using the equation: y×(1-x%)=A, calculate the thickness of the foam y=11.76mm.

(4) Using the equation: y×(z%-x%)=φ, calculate the total foam compression z%=71%, according to step (2) the foam pre-tightening compression amount x%, step (3) The thickness dimension y of the foam and the total compression z% of the foam are selected from PU foam.

Since there are 7 pieces of foam in the module of this embodiment, the thickness of each piece of foam is: y/7=1.68mm.

Finally, the foam specification in this module is: thickness: 1.68mm, compressible amount: 71%, and the corresponding pressure is 30KPa when the compression amount is 15%.

It can be seen from the above examples that the battery module foam selection method provided in this application as a technical selection scheme can guide the selection of soft-pack battery module foam, and the foam selection scheme can be scientifically Quantify, greatly reduce the foam selection process, improve the efficiency of cell design and product reliability, and solve the problem of battery pre-tightening force and cell expansion space in the module.

The applicant declares that this application uses the above-mentioned embodiments to illustrate the detailed methods of this application, but this application is not limited to the above detailed methods, which does not mean that this application must rely on the above detailed methods to be implemented.

Claims

A method for selecting battery module foam, which includes the following steps:

(1) Measure cell pre-tightening force F and cell expansion space φ;

(2) Using the cell pre-tightening force F and the foam pressure deformation characteristics described in step (1) to determine the foam pre-tightening compression amount x%;

(3) Obtain the pre-tightened size A of the foam, and use the equation: y×(1-x%)=A to calculate the thickness of the foam y;

(4) Using the equation: y×(z%-x%)=φ, calculate the total foam compression z%, according to step (2) the foam pre-tightening compression x%, step (3) the foam The thickness of the cotton y and the total compression of the foam z% are used to select the foam.
The method for selecting battery module foam according to claim 1, wherein the foam comprises any one or at least two of polyurethane foam, ethylene-vinyl acetate copolymer foam or neoprene foam The combination.
The battery module foam selection method according to claim 1 or 2, wherein the size A of the foam pre-tensioned in step (3) is the difference between the width of the battery module and the total width occupied by other parts .
The method for selecting the battery module foam according to claim 3, wherein the total width occupied by the other components includes the total thickness of the battery cell.
The battery module foam selection method according to claim 4, wherein the total width occupied by the other parts further includes any one or at least two of the width of the heat shield, the heat conduction plate, the frame, or the glue .
The battery module foam selection method according to any one of claims 1 to 5, wherein, in step (1), the cell pre-tightening force F and the cell expansion space φ are tested by a cell pre-tensioning expansion detection device get.
The battery module foam selection method according to any one of claims 1-6, wherein the pressure deformation characteristics of the foam in step (2) are measured by measuring the strain of the foam under different stress conditions, and the results It is obtained by fitting a curve or characteristic equation.
The method for foam selection of a pool module according to any one of claims 1-7, which comprises the following steps:

(1) Measure cell pre-tightening force F and cell expansion space φ;

(2) Using the cell pre-tightening force F and the foam pressure deformation characteristics described in step (1) to determine the foam pre-tightening compression amount x%;

(3) Obtain the pre-tightened size A of the foam, and use the equation: y×(1-x%)=A to calculate the thickness of the foam y;

(4) Using the equation: y×(z%-x%)=φ, calculate the total foam compression z%, according to step (2) the foam pre-tightening compression amount x%, step (3) the foam The thickness of the cotton y and the total compression of the foam z%, select the foam;

Wherein, the cell pre-tightening force F and the cell expansion space φ are obtained by testing with a cell pre-tightening expansion detection device;

The pressure deformation characteristic of the foam is obtained by measuring the strain of the foam under different stress conditions, and fitting the result to a curve or characteristic equation;

The size A of the foam pre-tensioned is the difference between the width of the battery module and the total width occupied by other parts. The total width occupied by the other parts includes the battery core, heat insulation board, heat conducting board, frame or glue. The width.
A battery module comprising a battery cell and foam, the foam being selected according to the method for selecting battery module foam according to any one of claims 1-8.
A battery module includes a battery cell and foam, wherein the foam and the module satisfy the following size relationship:

y×(1-x%)=A;

y×(z%-x%)=φ;

Among them, A is the size of the foam pre-tightened, y is the thickness of the foam, x% is the compression of the foam, z% is the total compression of the foam, and φ is the expansion space of the cell.