CN219040564U

CN219040564U - Secondary battery and electricity utilization device

Info

Publication number: CN219040564U
Application number: CN202222774528.7U
Authority: CN
Inventors: 唐文
Original assignee: Jiangsu Zenio New Energy Battery Technologies Co Ltd
Current assignee: Jiangsu Zenio New Energy Battery Technologies Co Ltd
Priority date: 2022-10-21
Filing date: 2022-10-21
Publication date: 2023-05-16
Anticipated expiration: 2032-10-21

Abstract

The utility model belongs to the technical field of battery production and manufacturing, and particularly relates to a secondary battery, which comprises a plurality of bare cells, wherein a heat conduction structure is arranged between adjacent bare cells, each adjacent bare cell is provided with a first side face opposite to each other, and the heat conduction structure is provided with a heat conduction surface respectively in surface contact with each first side face. The utility model ensures the uniformity of heat distribution of the battery, and internal heat is not obviously accumulated in the charging and discharging process. In addition, the utility model also discloses an electric device.

Description

Secondary battery and electricity utilization device

Technical Field

The utility model belongs to the technical field of battery production and manufacturing, and particularly relates to a secondary battery and an electric device.

Background

Electrochemical energy storage devices are one of the important carriers of energy sources today, and as the demands for energy storage devices in life are increasing, the cell capacity and energy density of secondary batteries are increasing, which results in the secondary batteries becoming larger in size. Wherein, the heat generated by the large-volume secondary battery during charging and discharging is distributed unevenly in the interior, the closer to the geometric center position, the more serious the heat accumulation is, and the uneven temperature distribution leads to uneven electrochemical reaction distribution in the secondary battery, which can cause great increase of side reactions in the secondary battery. For example, in a lithium ion battery, uneven temperature distribution may cause local lithium precipitation, and at the same time, in a heat accumulation area, electrolyte decomposition and gas production are easily caused, so that the safety of the battery is endangered. For this reason, a new solution is needed to solve the above problems.

Disclosure of Invention

One of the objects of the present utility model is: aiming at the defects of the prior art, the secondary battery is provided, the heat distribution of the battery can be ensured to be uniform, and the internal heat is not obviously accumulated in the charge and discharge process.

In order to achieve the above purpose, the present utility model adopts the following technical scheme:

a secondary battery, comprising:

the device comprises a plurality of bare cells, wherein a heat conduction structure is arranged between every two adjacent bare cells;

the adjacent bare cells are provided with opposite first side surfaces, and the heat conducting structures are provided with heat conducting surfaces which are respectively in surface contact with the first side surfaces.

Preferably, the battery further comprises a housing, wherein a plurality of bare cells and heat conducting structures between adjacent bare cells are mounted in the housing together, and at least one side of each heat conducting structure is in surface contact with the housing.

Preferably, the outer surface of the bare cell is a diaphragm, and the diaphragm is in surface contact with the heat conduction surface.

Preferably, the thermal conductivity of the thermal conductive structure is 1-10 times of the thermal conductivity of the diaphragm, and the thermal conductivity of the thermal conductive structure is not less than 0.3W/(m.k).

Preferably, the heat conducting surface of the heat conducting structure is a plane or an arc surface, and the shape of the first side surface is matched with the heat conducting surface.

Preferably, the bare cell has a large area, and the first side surface is located in the large area.

Preferably, the heat conducting structure is a T-shaped structure or an I-shaped structure.

Preferably, the area of the first side surface is smaller than the area of the heat conducting surface, and the area of the larger surface of the heat conducting structure is larger than 30% -50% of the area of the larger surface of the bare cell.

Preferably, the thermal conductivity of the shell is less than or equal to the thermal conductivity of the thermal conductive structure.

The second object of the present utility model is: there is provided an electrical device comprising an electrical device as described above.

The secondary battery has the beneficial effects that the secondary battery comprises a plurality of bare cells, a heat conducting structure is arranged between the adjacent bare cells, the adjacent bare cells are provided with opposite first side surfaces, the heat conducting structure is provided with heat conducting surfaces which are respectively in surface contact with the first side surfaces, and the problem of uneven distribution of internal temperature of the large-volume secondary battery formed by the plurality of bare cells is solved.

Drawings

Features, advantages, and technical effects of exemplary embodiments of the present utility model will be described below with reference to the accompanying drawings.

Fig. 1 is a schematic structural diagram of embodiment 1 of the present utility model.

Fig. 2 is a schematic structural diagram of a heat conducting structure in embodiment 1 of the present utility model.

Fig. 3 is a schematic structural diagram of a heat conducting structure in embodiment 2 of the present utility model.

Wherein reference numerals are as follows:

1. a bare cell; 2. a thermally conductive structure; 3. a housing.

Detailed Description

Certain terms are used throughout the description and claims to refer to particular components. Those of skill in the art will appreciate that a hardware manufacturer may refer to the same component by different names. The description and claims do not take the form of an element differentiated by name, but rather by functionality. As used throughout the specification and claims, the word "comprise" is an open-ended term, and thus should be interpreted to mean "include, but not limited to. By "substantially" is meant that within an acceptable error range, a person skilled in the art can solve the technical problem within a certain error range, substantially achieving the technical effect.

In the description of the present utility model, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "horizontal", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are merely for convenience in describing the present utility model and simplifying the description, and do not indicate or imply that the device or element being referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present utility model.

In the present utility model, unless explicitly specified and limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present utility model can be understood by those of ordinary skill in the art according to the specific circumstances.

The inventors have found that temperature is an important factor affecting the performance of an electrochemical secondary battery, and is a major design rule for whether the secondary battery can be applied in a wide region. Along with the increasing demands on the energy storage device in life, the demands on the stability of the working time and the convenience of the usable environment are increased, so that the single capacity and the energy density of the secondary battery are increased, the secondary battery can be used for storing enough energy, and meanwhile, the charging and discharging speeds are also increased. In the prior art, the increase of the electrode tab length can be used to increase the active material mass, or multiple winding cores can be connected in parallel in the same case to increase the capacity and energy density of the secondary battery cell, which results in an increasingly larger volume of the secondary battery. However, the larger the volume of the secondary battery, the more the heat generated during charge and discharge is distributed unevenly inside, the more the heat is accumulated closer to the geometric center; the need for both rapid charging and discharging results in heat generation in a short period of time, which is less than that of conduction to the surrounding environment, further exacerbating the heat build-up problem. The uneven temperature distribution causes uneven electrochemical reaction distribution in the secondary battery, which can cause great increase of side reactions in the secondary battery, for example, in the lithium battery, the uneven temperature distribution can cause local lithium precipitation, and meanwhile, in the heat accumulation area, electrolyte decomposition and gas production are easily caused, so that the safety of the battery is endangered. In winter, the capacity of the secondary battery can be greatly reduced, and part of the system batteries can not work even because of the rapid increase of polarization under severe cold. Therefore, the use of new energy vehicles using secondary batteries as energy storage devices is greatly restricted in the cold.

At the use end of the secondary battery, the heat management system is often utilized to dissipate heat or increase the temperature of the battery core during initial discharge to improve the electrochemical reaction condition, so that the secondary battery can work healthier, for example, an air cooling or liquid cooling system is used, and circulating cooling liquid is used for taking away the heat on the surface of the secondary battery, so that the temperature difference between the inside and outside of the secondary battery is increased, and the heat transfer speed is accelerated; however, the inventors found that in the case where the capacity and energy density requirements are continuously increased, a large battery volume poses a challenge for rapid heat conduction, and that the larger the volume, the longer the time required for uniform heat distribution throughout the secondary battery, the more limited the effect can be brought, and the temperature in the central region of the battery is always higher than the surface layer temperature, and the problem of uneven temperature distribution is always present. Therefore, a new secondary battery structure is required to solve and improve the above problems.

A secondary battery, comprising:

the plurality of bare cells 1 are provided with heat conduction structures 2 between adjacent bare cells 1;

the adjacent bare cells 1 have opposite first side surfaces, and the heat conducting structure 2 has heat conducting surfaces respectively in surface contact with the first side surfaces.

The heat conduction surfaces of the heat conduction structures 2 are used for uniformly transferring heat among the bare cells 1, so that the heat of each bare cell 1 is uniformly distributed, the heat accumulation condition of the center of the cell is improved, and the internal heat of the battery is not obviously accumulated in the charging and discharging process.

In the secondary battery, the heat conducting structure 2 is made of a heat conducting material, and the heat conducting material can be one or more of metal, alloy or modified material thereof, silicon, modified material thereof, carbon material, composite modified material thereof, heat conducting mica sheet, heat conducting glue and heat conducting ceramic; more preferably, graphite and its composite material are selected. In addition, the heat conduction structure 2 and the electrolyte of the secondary battery do not chemically react, the structural strength and the heat conduction characteristic of the heat conduction structure 2 are not weakened by the electrolyte, the electrolyte can freely infiltrate each bare cell 1, and the heat conduction structure 2 is not unevenly distributed.

In the present application, the secondary battery may be a device that can be used for electrochemical energy storage, such as a lithium ion battery, a sodium ion battery, a potassium ion battery, an aluminum ion battery, etc., and the number of the plurality of bare cells 1 is greater than or equal to 2.

In addition, the secondary battery further comprises a shell 3, the plurality of bare cells 1 and the heat conducting structures 2 between the adjacent bare cells 1 are jointly installed in the shell 3, at least one side of each heat conducting structure 2 is in surface contact with the shell 3, and at least one side of each heat conducting structure 2 is fully contacted with the shell 3. Preferably, the heat conductive structure 2 is closely connected to the case 3 of the secondary battery, the heat conductive structure 2 may be in flat contact with the case 3, and one side of the heat conductive structure 2, which is preferentially in contact, is a "T" shaped structure.

In the secondary battery, the outer surface of the bare cell 1 is a diaphragm, the diaphragm is in surface contact with the heat conduction surface, when the bare cell 1 is a winding core prepared in a winding mode, the heat conduction structure 2 is preferentially contacted with two sides of the shell 3, and the contact part of the heat conduction structure 2 and the shell 3 can not interfere with the winding core, so that heat generated by the winding core can be quickly transferred to the shells 3 on two sides through the heat conduction structure 2 and can be quickly dispersed, and the heat accumulation condition of the center of the winding core is improved.

In the secondary battery, when the bare cell 1 is prepared in a lamination mode, the heat conduction structure 2 is preferably in contact with the bottom side of the shell 3, and the contact surface is the whole bottom surface, so that when the volume expansion of the cell possibly occurs in the charging process, the heat conduction structure 2 does not exert force on the cell, and the deformation of the cell is not caused, so that the performance of the secondary battery is not affected.

Wherein, the material of the shell 3 is one of an aluminum shell, a steel shell, an aluminum plastic film and a material which can be used as a secondary battery shell in the industry, and more preferably, the aluminum shell is selected as the shell 3.

In addition, if the casing 3 is connected with the anode of the secondary battery, the connection part of the heat conducting structure 2 and the casing 3 is connected by using a heat conducting insulating mica sheet or a heat conducting ceramic, so that the corrosion or other side reactions of the casing 3 caused by the electrochemical reaction between the heat conducting structure 2 and the casing 3 can be prevented.

In the secondary battery, the bare cell 1 is provided with a large area, the first side face is positioned in the large area, and the large area of the heat conduction structure 2 is contacted with the large area of the bare cell 1, so that the heat conduction effect of the heat conduction structure 2 and the bare cell 1 is guaranteed to be better.

Preferably, the area of the first side surface is smaller than the area of the heat conducting surface, the area of the larger surface of the heat conducting structure 2 is larger than 30% -40%, 40% -50% and more preferably larger than 50% of the area of the larger surface of the bare cell 1, so that the phenomenon that the contact surface of the bare cell 1 and the heat conducting structure 2 is too small due to the influence of the too small area of the heat conducting structure 2 is avoided, the heat transfer efficiency is low, and meanwhile uneven stress at the contact position can be avoided, and the deformation of the cell is avoided.

Preferably, the thermal conductivity of the thermal conductive material used in the thermal conductive structure 2 is greater than the thermal conductivity of the diaphragm in the bare cell 1, and is greater than 0.3W/(m·k), more preferably greater than 2W/(m·k), and the thermal conductivity of the thermal conductive structure 2 may be 1 to 10 times that of the diaphragm.

Preferably, the heat conducting surface of the heat conducting structure 2 is a plane or an arc surface, and the shape of the first side surface is matched with the heat conducting surface.

Preferably, the heat conducting structure 2 is a T-shaped structure or an i-shaped structure.

Preferably, the thermal conductivity of the housing 3 is less than or equal to the thermal conductivity of the thermally conductive structure 2.

An electric device includes the secondary battery as described above.

The present utility model will be described in further detail below with reference to fig. 1 to 3 and the specific embodiments, but is not limited thereto.

Example 1

Referring to fig. 1, a secondary battery is provided, which comprises a bare cell 1, a heat conducting structure 2, a shell 3 and an electrolyte, wherein the heat conducting structure 2 is arranged between adjacent bare cells 1, and the battery is a lithium ion secondary battery, the bare cells 1 are wound cores, and the secondary battery is manufactured in a winding manner according to the operations of preparing positive and negative pole pieces, manufacturing the wound cores, adhering the wound cores with the heat conducting structure 2, housing, packaging, detecting tightness, injecting liquid, forming, supplementing liquid and separating capacity, thus completing battery preparation, wherein the nominal capacity of the battery at room temperature is 100Ah, and the wound cores are manufactured in a winding manner. Referring to fig. 2, the heat conductive structure 2 is an i-shaped structure, both sides of the heat conductive structure 2 are connected with the case 3 of the secondary battery in a T-shaped joint, and the large area of the winding core is 80% of the large area of the heat conductive structure 2, and the large area of the heat conductive structure 2 is one side of a middle vertical flat plate of the i-shaped structure.

The full charge lithium ion secondary battery is subjected to 1C test charge and discharge test in an incubator at 25 ℃, and the ambient temperature, the large-surface temperature, the side temperature, the bottom temperature and the core center temperature are recorded by using thermocouples, and the core center temperature can be measured by embedding the thermocouples in the battery manufacturing process.

And then placing the full-charge lithium ion secondary battery in an incubator at the temperature of minus 20 ℃ for 2 hours, immediately performing 0.2C discharge for 12 minutes after the battery is moved into the incubator at the temperature of 25 ℃ for 5 minutes, simulating the discharge condition of the battery under the condition of external heating in a cold environment, and recording the discharge capacity.

Example 2

Based on the procedure of example 1, the bare cell 1 was manufactured in a lamination manner, and referring to fig. 3, the heat conducting structure 2 is a T-shaped structure, the bottom side of the heat conducting structure 2 is connected with the bottom surface of the secondary battery case by a T-shaped joint, the large area of the bare cell 1 is 80% of the large area of the heat conducting structure 2, and the nominal capacity of the battery at room temperature is 100Ah.

The fully charged lithium ion secondary battery is subjected to 1C discharge test in an incubator at 25 ℃, and the environmental temperature, the large-surface temperature, the side surface temperature, the bottom temperature and the core center temperature after discharge are recorded by using a thermocouple, and the core center temperature can be measured by embedding the thermocouple in the battery manufacturing process.

Comparative example

The same test was performed with the heat conducting structure 2 removed on the basis of example 1.

Test records for the various embodiments are shown in the following table:

table 1 is a table showing the cases where the secondary batteries of the respective examples were subjected to a 1C test charge and discharge test in an incubator at 25 ℃.

Examples	Ambient temperature	Large surface temperature	Side temperature	Bottom surface temperature	Center temperature
						Example 1	25.1	30.4	29.8	29.3	32.2
Example 2	25.0	30.9	29.4	29.7	32.9
						Comparative example	24.9	31.3	29.2	28.8	34.6

TABLE 1

Table 2 shows the conditions of the secondary batteries of the respective examples immediately after being transferred into an incubator at 25℃for 5 minutes and then subjected to a 0.2C discharge for 12 minutes.

TABLE 2

As is clear from tables 1 and 2, the secondary batteries of examples 1 and 2 of the present application have the heat conductive structure 2 between the adjacent bare cells 1, and therefore, the secondary batteries do not have significant internal heat accumulation during charge and discharge, and have heat supplementation and high capacity performance at lower temperatures.

Obviously, this scheme is through making the even heat transfer of heat conduction surface through heat conduction structure between a plurality of bare cell for the heat distribution of each bare cell is even, thereby reaches the situation that improves the heat accumulation at electric core center.

Variations and modifications of the above embodiments will occur to those skilled in the art to which the utility model pertains from the foregoing disclosure and teachings. Therefore, the present utility model is not limited to the above-described embodiments, but is intended to be capable of modification, substitution or variation in light thereof, which will be apparent to those skilled in the art in light of the present teachings. In addition, although specific terms are used in the present specification, these terms are for convenience of description only and do not limit the present utility model in any way.

Claims

1. A secondary battery, characterized by comprising:

the device comprises a plurality of bare cells (1), wherein a heat conduction structure (2) is arranged between the adjacent bare cells (1);

the adjacent bare cells (1) are provided with opposite first side surfaces, and the heat conducting structures (2) are provided with heat conducting surfaces which are respectively contacted with the first side surfaces.

2. The secondary battery according to claim 1, wherein: the battery pack also comprises a shell (3), wherein a plurality of bare cells (1) and heat conducting structures (2) between the adjacent bare cells (1) are jointly installed in the shell (3), and at least one side of each heat conducting structure (2) is in surface contact with the shell (3).

3. A secondary battery according to claim 1 or 2, wherein: the external surface of the bare cell (1) is a diaphragm, and the diaphragm is in surface contact with the heat conduction surface.

4. A secondary battery according to claim 3, wherein: the heat conduction coefficient of the heat conduction structure (2) is 1-10 times of that of the diaphragm, and the heat conduction coefficient of the heat conduction structure is not less than 0.3W/(m.k).

5. A secondary battery according to claim 1 or 2, wherein: the heat conduction surface of the heat conduction structure (2) is a plane or an arc surface, and the shape of the first side surface is matched with the heat conduction surface.

6. A secondary battery according to claim 1 or 2, wherein: the bare cell (1) is provided with a large area, the first side face is positioned in the large area, and the area of the first side face is smaller than that of the heat conducting surface.

7. The secondary battery according to claim 6, wherein: the large area of the bare cell (1) is 80% of the large area of the heat conducting structure (2).

8. A secondary battery according to claim 1 or 2, wherein: the heat conduction structure (2) is of a T-shaped structure or an I-shaped structure.

9. The secondary battery according to claim 2, wherein: the thermal conductivity of the shell (3) is smaller than or equal to the thermal conductivity of the thermal conductive structure (2).

10. An electrical device, characterized in that: a secondary battery comprising the battery according to any one of claims 1 to 9.