CN220290933U - Single battery and battery module - Google Patents

Abstract

The application relates to a battery cell and battery module, this battery cell includes: the battery cell is provided with a tab; a top cover provided with a through hole and a terminal hole; and the terminal piece part is penetrated from the terminal hole to the top cover, the terminal piece comprises a first terminal part, the first terminal part is positioned between the top cover and the tab, the first terminal part is welded and fixed with the tab, and the through hole is used for enabling the first terminal part and the tab to be welded. The single battery and the battery module can improve the space utilization rate so as to improve the energy density of the single battery.

Description

Single battery and battery module

Technical Field

The application relates to the field of batteries, in particular to a single battery and a battery module.

Background

The battery cells are used as core components and energy sources of electric vehicles, and the storage capacity of the battery cells determines the endurance mileage of the vehicle, so how to increase the energy density to increase the energy storage capacity is also important in research. The battery cell is generally composed of a top cover, a bottom shell, a battery cell and the like, and when the battery cell is welded with an electrode terminal, a tab arranged on the battery cell is generally required to be folded, so that a folding space is reserved, and therefore a space is reserved between the battery cell and the top cover, and space waste is caused.

Disclosure of Invention

An object of the present application is to provide a single battery and a battery module, which can improve the space utilization rate to improve the energy density of the single battery.

To this end, in a first aspect, embodiments of the present application provide a single battery, including:

the battery cell is provided with a tab;

a top cover provided with through holes and terminal holes which are arranged at intervals; and

a terminal member, the terminal member portion penetrating the top cover from the terminal hole,

the terminal piece comprises a first terminal part, the first terminal part is located between the top cover and the tab, the first terminal part is fixedly welded with the tab, and the through hole is used for enabling the first terminal part and the tab to be welded.

In an alternative embodiment, the first terminal portion has a welding area, the orthographic projection of the welding area on the battery cell is located on the tab along the first direction Z, and the orthographic projection of the through hole on the first terminal portion is located at least partially on the welding area.

In an alternative embodiment, in the orthographic projection of the top cover to the battery core, the through hole has a first area S1, the welding area has a second area S2, S2 is less than S1, the first terminal portion has a third area S3, S2 is less than or equal to 30% X S3, wherein the first area S1 is a sectional area of a surface of the through hole in the first direction X and the third direction Y, the third area S3 is a projection area of a surface of the first terminal portion in the first direction X and the third direction Y, facing to one side of the tab, of the first terminal portion, and the second area S2 is an area enclosed by welding tracks on the welding area.

In an alternative embodiment, the first terminal portion thickness is no greater than 3mm along the first direction Z.

In an alternative embodiment, the terminal piece further comprises a second terminal part connected to the first terminal part, and the second terminal part is electrically or insulatively connected to the top cover through the terminal hole.

In an alternative embodiment, the first terminal portion is a terminal plate of plate-like configuration,

and one end of the terminal plate is provided with the welding area, the other end of the terminal plate is connected with the second terminal part along the second direction X, and the first direction Z is intersected with the second direction X.

In an alternative embodiment, an insulator is further included between the first terminal portion and the top cover.

In an alternative embodiment, the device further comprises an explosion-proof valve, and the explosion-proof valve is arranged in the through hole.

In an alternative embodiment, the sealing part is disposed in the through hole and is used for sealing the through hole.

In an alternative embodiment, the sealing device further comprises a liquid injection hole, and the liquid injection hole is arranged on the sealing part.

In an alternative embodiment, along the first direction Z, the sealing portion has a first thickness d1, the cap has a second thickness d2, d1 < d2, and d2 < 10mm.

In a second aspect, embodiments of the present application provide a battery module comprising a single cell as described in the foregoing.

According to the single battery and the battery module provided by the embodiment of the application, through the through hole, the through hole is at least partially positioned above the overlapped welding area joint lug in the first direction, and the welding fixation of the first terminal part and the lug can be realized by directly utilizing the penetrating welding mode from the upper part through the through hole. Through this kind of mode, when being convenient for realize terminal part and tab welding, the tab can not buckle, can not additionally increase the space between top cap and the electric core, or the space of electric core and casing, avoid causing the waste of holding chamber inner space, improve space utilization to promote single cell's energy density.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, a brief description will be given below of the drawings that are needed in the embodiments or the prior art descriptions, and it is obvious that the drawings in the following description are some embodiments of the present application, and that other drawings can be obtained according to these drawings without inventive effort for a person skilled in the art. In addition, in the drawings, like parts are designated with like reference numerals and the drawings are not drawn to actual scale.

Fig. 1 shows an overall structure schematic diagram of a single battery provided in an embodiment of the present application, where a direction indicated by an arrow X is a second direction, a direction indicated by an arrow Y is a third direction, and a direction indicated by an arrow Z is a first direction.

Fig. 2 shows an exploded view of a single battery according to an embodiment of the present application, where a direction indicated by an arrow X is a second direction, a direction indicated by an arrow Y is a third direction, and a direction indicated by an arrow Z is a first direction;

fig. 3 is a schematic structural diagram of a battery cell and a terminal member in a single battery according to an embodiment of the present application;

fig. 4 is a schematic structural view of a top cover and a terminal member in a single battery according to an embodiment of the present disclosure;

fig. 5 is a front view, partially in section, showing the cooperation of a top cover and a terminal member in a single battery according to an embodiment of the present application;

fig. 6 shows a schematic diagram of a top cover structure in another single battery according to an embodiment of the present disclosure;

FIG. 7 shows a schematic structural view of a seal in cooperation with FIG. 6;

fig. 8 is a schematic diagram showing a top cover structure in another single battery according to an embodiment of the present disclosure;

fig. 9 shows a schematic diagram of a top cover structure in still another single battery according to an embodiment of the present application.

Reference numerals:

100-single battery; 1-an electric core; 11-electrode lugs; 111-a first surface; 2-top cover; 21-a through hole; 22-terminal holes; 23-a liquid injection hole; 24-explosion-proof valve hole; 3-a housing; 31-a receiving chamber; 4-terminal pieces; 41-a first terminal portion; 411-welding area; 42-a second terminal portion; 421-limit plates; 5-insulating member; 6-sealing part; 7-explosion-proof valve.

Detailed Description

For the purposes of making the objects, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions of the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is apparent that the described embodiments are some embodiments of the present application, but not all embodiments. All other embodiments, which can be made by one of ordinary skill in the art without undue burden from the present disclosure, are within the scope of the present application based on the embodiments herein.

Fig. 1 shows an overall structure schematic diagram of a single battery provided in an embodiment of the present application. Fig. 2 shows an exploded view of a single battery provided in an embodiment of the present application. Fig. 3 is a schematic structural diagram of a battery cell and a terminal member in a single battery according to an embodiment of the present application. The direction indicated by the arrow X is a second direction, the direction indicated by the arrow Y is a third direction, the direction indicated by the arrow Z is a first direction, the first direction Z, the second direction X and the third direction are intersected, preferably, the first direction Z, the second direction X and the third direction Y are mutually perpendicular, the first direction Z is the height direction of the single battery, the second direction X is the length direction of the single battery, the third direction Y is the thickness direction of the single battery, and the single battery is not emphasized later.

The single battery 100 comprises a shell 3, a battery cell 1 and a top cover 2, wherein the shell 3 is provided with an opening, and the top cover 2 covers the opening of the shell 3 to form an accommodating space for accommodating the battery cell 1, so that the single battery 100 is assembled. The single battery 100 can be directly used in fields with less energy requirements such as digital products. Alternatively, a plurality of unit batteries 100 may be provided, and a plurality of unit batteries 100 are assembled to form a battery module, and a plurality of battery modules are combined to form a battery pack, so that the battery pack is used in the energy storage fields of new energy automobiles with larger energy demands, power grids and the like, and the battery pack is not particularly limited herein.

It can be appreciated that the single battery 100 is an aluminum-shell battery, and the aluminum-shell battery has the advantage of high single energy density compared with other types of lithium ion batteries, and is widely applied to new energy automobiles, and the specific matching structure of the single battery 100 will be described in detail below by taking the application of the single battery 100 to the new energy automobiles as an example.

The unit battery 100 includes a terminal member 4, the battery cell 1 has a tab 11, the top cover 2 is provided with a terminal hole 22, a part of the terminal member 4 is located in the accommodating cavity 31 and is used for being connected with the tab 11, and the other part of the terminal member is penetrated from the terminal hole 22 to the top cover 2. It can be understood that the side of the battery core 1 facing the top cover 2 is provided with a first tab 11 and a second tab 11 which are arranged at intervals in the length direction, the two tabs 11 are respectively connected with the terminal piece 4, the terminal piece 4 partially extends out of the top cover 2 from the accommodating cavity 31, and the terminal piece 4 of the extending part is used for being connected with the outside to realize positive and negative electrodes so as to supply energy. One of the first tab 11 and the second tab 11 is used as a positive electrode tab 11, and the other is used as a negative electrode tab 11, so that one of the corresponding extended terminal pieces 4 is used as a positive electrode, and the other is used as a negative electrode to realize electrical connection.

In the process of assembling the unit battery 100, it is necessary to insulate or electrically connect the terminal member 4 with the top cover 2 (a suitable connection method is selected according to the positive and negative electrodes, and not described in detail herein), and then weld the terminal member 4 with the tab 11. In order to facilitate the realization of welding, a certain amount of lug 11 can be directly folded in a first direction Z to form a folding space, a certain space for accommodating the folded lug 11 exists between one side of the lug 11 arranged on the battery cell 1 and the top cover 2 for welding and fixing, a certain amount of lug 11 can be folded to the side wall of the battery cell 1, connection is realized by using an adapter plate, a bus bar and the like, and the space between the battery cell 1 in a second direction X or a third direction Y and the shell 3 is increased, so that space waste is caused.

In order to solve the above-mentioned problems, the embodiment of the present application provides a single battery 100, and the specific configuration of one of the tabs 11, the terminal member 4 and the top cover 2 is taken as an example, and the single battery 100 in the embodiment of the present application will be described in detail below.

Referring to fig. 1 to 3, in the single battery 100 according to the embodiment of the present application, the terminal member 4 specifically includes a first terminal portion 41, the top cover 2 is provided with through holes 21 and terminal holes 22 that are disposed at intervals, the first terminal portion 41 is located between the top cover 2 and the tab 11, the first terminal portion 41 is welded to the tab 11, and the through holes 21 are used for welding the first terminal portion 41 and the tab 11. Through this kind of mode, when being convenient for realize terminal piece 4 and tab 11 welding, tab 11 need not buckle, can not additionally increase the space between top cap 2 and the electric core 1, or the space of electric core 1 and casing 3, avoid causing the waste of holding chamber 31 inner space, improve space utilization to promote the energy density of battery cell 100.

Optionally, the first terminal portion 41 has a welding area 411, along the first direction Z, the front projection of the welding area 411 on the battery core 1 is located on the tab 11, and the front projection of the through hole 21 on the first terminal portion 41 is at least partially located on the welding area 411, the first terminal portion 41 is welded to the tab 11, and the through hole 21 is used for implementing penetration welding between the first terminal portion 41 and the tab 11. The first terminal portion 41 and the tab 11 at the position of the land 411 can be welded and fixed by the through-hole 21 being provided so that the through-hole 21 is located at least partially above the overlapped land 411 and the tab 11 in the first direction Z, and by applying the through-hole 21 to the land 411 by means of penetration welding directly from above.

It is to be understood that, in the welding structure of one tab 11 and terminal member 4, one through hole 21 corresponding to one welding area 411 may be provided, or may be formed by a combination of a plurality of spaced or connected holes, so long as a region opposing welding area 411 is provided for through hole 21. The welding gun for penetration welding can pass over the top plate by the arranged through holes 21, welding is realized by directly using the overlapping part of the first terminal part 41 and the tab 11 which are arranged in a laminated way by penetration welding from the upper part, and welding slag is avoided, so that the phenomenon that the welding slag easily falls to the battery cell 1 to influence the service performance is avoided.

Alternatively, the tab 11 has a first surface 111 facing the top cover 2, the first terminal portion 41 is located above the first surface 111, and at least an orthographic projection of the soldering region 411 in the first direction Z is located on the first surface 111. When penetration welding is performed, enough overlapping area can be ensured, so that a good welding and fixing effect is ensured.

Alternatively, the through hole 21 may be provided as a circular through hole, or may be provided as a non-circular hole, such as an elliptical hole, a quadrangular hole, a hexagonal hole, or the like, without being particularly limited thereto. The shape of the welding area 411 may be adaptively adjusted according to the actual requirements, and is not particularly limited herein. In order to facilitate penetration welding and ensure stability and reliability of welding, the through hole 21 is disposed opposite to the welding area 411 along the first direction Z, and the through hole 21 and the welding area 411 are disposed in the same shape, for example, the through hole 21 is disposed in a circular shape, the welding area 411 is also disposed in a circular shape coaxial with the through hole 21, the through hole 21 is disposed in a racetrack-shaped elliptical structure, and the welding area 411 is also disposed in a center-identical elliptical structure with the same shape, which is not particularly limited herein.

The specific fitting structure of one of the tabs 11, the terminal member 4, and the top cover 2 in the embodiment of the present application will be described in detail below taking an elliptical structure in which the through hole 21 and the land 411 are provided to be the same as each other.

In an alternative embodiment, in the front projection of the top cover 2 to the battery cell 1, the through hole 21 has a first area S1, the land 411 has a second area S2, S2 < S1, the first terminal portion 41 has a third area S3, S2 is 30% x S3, optionally, 5% x S3 is 2 < 25% x S3, or 15% x S3 < S2 < 25% x S3. That is, the cross-sectional area of the through hole 21 is the first area S1, the area surrounded by the welding trace on the welding area 411 is the second area S2, and the first terminal 41 has the third area S3 on the side facing the tab 11 on the surface where the second direction X and the third direction Y are located. In the orthographic projection of the through hole 21 along the first direction Z of the first terminal portion 41, the cross section of the through hole 21 is larger than the area of the welding area 411, so that the welding area 411 can be completely exposed from the through hole 21, so that sufficient welding area is ensured, and the overcurrent capacity and the capacity retention rate are good when the battery is used, so that the stability and the firmness of the fixed connection of the first terminal portion 41 and the tab 11 are improved.

The sizes of S1 and S3 can be measured by an area measuring instrument, S2 can be a closed pattern formed by measuring the outer periphery of the welding track area by using a marker, the area of the part surrounded by the surfaces of the part in the second direction X and the third direction Y is a second area S2, and the area size of the part is measured by the area measuring instrument to be the value of S2.

It is to be understood that the size and shape of the second area S2 provided in the bonding area 411 may be adaptively adjusted according to different requirements, which is not specifically limited herein.

Optionally, several sets of data, in which the second area S2 of the welding area 411 is set to be different, are selected to perform the welding strength and the service performance of the single battery 100, which is specifically as follows:

when S2 is 4% multiplied by S3, the test result shows that: the welding strength cannot meet the set minimum strength requirement, the overcurrent capacity cannot meet the minimum overcurrent capacity requirement in the use process of the battery, the welding strength is insufficient and is easy to fall off, the overcurrent capacity is reduced when the single battery 100 is used, the capacity retention rate is reduced, and the problem of waste of the tab 11 is avoided;

when S2 is 8 percent multiplied by S3, the test result shows that: the welding strength can reach the set minimum strength requirement, the overcurrent capacity of the single battery 100 can basically reach the minimum overcurrent capacity requirement in the use process, and the problem of waste of the tab 11 is avoided;

when S2 is 20%. Times.S3, the test result shows that: the welding strength is high, the overcurrent capacity and the capacity retention rate of the single battery 100 are good in the use process, the welding area is proper, and the waste of the electrode lugs 11 is avoided;

when S2 is 30 percent multiplied by S3, the test result shows that: the welding strength is high, the overcurrent capacity and the capacity retention rate of the single battery 100 are good in the use process, the welding area is slightly larger, and a certain tab 11 is wasted;

when S2 is 40% multiplied by S3, the test result shows that: the welding strength is higher, and the overcurrent capacity and the capacity retention rate are lower in the use process of the single battery 100, and the welding area is overlarge, so that the waste of the tab 11 is serious.

Thus, setting the second area S2 to 5% x S3.ltoreq.S2.ltoreq.30% x S3 ensures that a certain weld strength is ensured, and at the same time, a good overcurrent capacity and capacity retention rate are ensured, and preferably, the most preferred range is 10% x S3.ltoreq.S2.ltoreq.20% x S3, tested by a plurality of sets of different data, and detailed description is omitted herein.

Alternatively, the first terminal portion 41 has a thickness of not more than 3mm in the first direction Z. To ensure that the torch head is capable of achieving a penetration weld fit with the tab 11 at the weld zone 411 of the first terminal portion 41. Preferably, the thickness of the first terminal portion 41 is 2mm-3mm, so that the problem that the first terminal portion 41 is easy to warp and deform or even damage the first terminal portion 41 to penetrate the tab 11 during welding, and therefore welding fixation cannot be achieved is avoided.

In an alternative embodiment, referring to fig. 4 and 5, the terminal member 4 further includes a second terminal portion 42 connected to the first terminal portion 41, and the second terminal portion 42 is electrically or insulatively connected to the top cover 2 through the terminal hole 22. Along the first direction Z, the second terminal portion 42 is connected to a side of the first terminal portion 41 away from the tab 11, so that the second terminal portion 42 protrudes from the first terminal portion 41 in the first direction Z, and the first terminal portion 41 can protrude from the terminal hole 22 out of the top cover 2, and can be electrically connected or insulated with the top cover 2 according to positive and negative requirements.

Likewise, the specific shapes and sizes of the terminal hole 22 and the second terminal portion 42 may be adaptively adjusted according to practical situations, in this embodiment, the terminal hole 22 is set to be a round hole, and the second terminal portion 42 is set to be a columnar structure in clearance fit with the terminal hole 22, which is not described herein.

Alternatively, the first terminal portion 41 and the second terminal portion 42 may be made of the same material as the top cover 2, and the first terminal portion 41 and the second terminal portion 42 that are connected may be an integrally formed structure, or may be a split structure that is fixed together by welding or the like, which is not particularly limited herein.

In the embodiment, the first terminal 41 is a plate-shaped terminal board, and one end of the terminal board is provided with a soldering area 411 along the second direction X, and the other end is connected to the second terminal 42. The terminal board can occupy the space of the accommodating cavity 31 to a minimum, and can separate the welding area 411 from the second terminal portion 42, so as to avoid the second terminal portion 42 from influencing the penetration welding fixation performed in the welding area 411, and improve the penetration welding efficiency.

In addition, an insulating member 5 may be further included, the insulating member 5 being located between the first terminal portion 41 and the top cover 2. The other portions of the terminal piece 4 than the second terminal portion 42 are prevented from contacting the top cover 2 to prevent a problem of contact short circuit.

Optionally, a limiting plate 421 is disposed at an edge of the second terminal portion 42 near the first terminal portion 41, and the limiting plate 421 extends out of the second terminal portion 42 in a radial direction to form a step structure of the second terminal portion 42. When the second terminal portion 42 is fitted to the top cover 2, the stopper 421 of the stepped portion does not protrude from the terminal hole 22 along with the second terminal portion 42, and the end surface of the stopper 421, which is stepped, abuts against the lower surface of the top cover 2, with a gap between the first terminal portion 41 and the lower surface of the top cover 2. The insulating member 5 may be provided in a nonmetallic plate-like structure so as to be placed at the gap position, thereby achieving insulation of the terminal member 4 from other portions of the top cover 2 than the positive electrode. Preferably, the insulator 5 is disposed between the two second terminal portions 42 in the second direction X.

It will be appreciated that the thickness of the insulating member 5 with a plate-like structure may be adaptively adjusted according to the size of the gap, so long as the size of the gap is not exceeded, and the size and shape of the insulating member 5 may be matched according to actual requirements, which is not particularly limited herein.

In an alternative embodiment, fig. 6, 8 and 9, further include a liquid injection hole 23 and an explosion-proof valve 7, which are respectively disposed on the top cover 2, and the explosion-proof valve 7 is disposed on the through hole 21. In order to avoid the influence of the through-holes 21 provided in the top cover 2 on the battery performance, after the through-holes 21 are used for the penetration welding fixation, one of the through-holes 21 may be used as the injection hole 23, and the size of the through-hole 21, the position relative to the top cover 2, the arrangement of the terminal member 4, and the like may be adaptively adjusted according to the actual situation. The other through hole 21 is used as an explosion-proof valve hole 24, and the explosion-proof valve 7 is sealingly mounted at the position of the through hole 21, which will not be described in detail here.

In an alternative embodiment, referring to fig. 2 and 7, the sealing part 6 is further included, and is disposed in the through hole 21, for sealing the through hole 21. After the penetration welding fixation is achieved, the through-hole 21 can be plugged by the provided sealing part 6 to ensure the performance of the unit cell 100.

Alternatively, the through hole 21 may be provided as a stepped hole for accommodating and supporting the sealing portion 6, so as to prevent the sealing portion 6 from falling from the through hole 21 before being sealingly connected to the through hole 21.

It is to be understood that the liquid filling hole 23 and the explosion-proof valve 7 provided in the top cover 2 may be provided at positions corresponding to the top cover 2 separately, or at least one of them may be provided in the sealing portion 6. When the liquid filling hole 23 and the explosion-proof valve 7 are provided in the sealing portion 6, they may be provided in the sealing portion 6 corresponding to the two different through holes 21, or may be provided in the same sealing portion 6, and are not particularly limited.

Alternatively, in the first direction Z, the sealing portion 6 has a first thickness d1, the cap 2 has a second thickness d2, d1 < d2, and d2 < 10mm. While ensuring the sealing performance, the sealing part 6 does not exceed the top cover 2 in the height direction, so that the overall performance of the single battery 100 is not affected.

In a second aspect, the embodiment of the present application provides a battery module, including the single battery 100 described in the foregoing embodiment, which may be applied to an electric vehicle, for example, a new energy vehicle, where a battery pack is provided, the battery pack is composed of a battery module, and the battery module includes a plurality of single batteries 100 assembled in a certain combination, and the single batteries 100 are the single batteries 100 described in the foregoing embodiment, which is not described in detail herein.

It should be noted that, the single battery 100 and the battery module provided in the embodiments of the present application are not limited to be applied to a new energy automobile, but may be applied to other devices needing energy storage, such as a power grid, an energy storage cabinet, and the like, which are not described again.

It should be noted that references in the specification to "one embodiment," "an example embodiment," "some embodiments," etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Furthermore, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to effect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.

It should be readily understood that the terms "on … …", "above … …" and "above … …" in this disclosure should be interpreted in the broadest sense such that "on … …" means not only "directly on something", but also includes "on something" with intermediate features or layers therebetween, and "above … …" or "above … …" includes not only the meaning "on something" or "above" but also the meaning "above something" or "above" without intermediate features or layers therebetween (i.e., directly on something).

Further, spatially relative terms, such as "below," "beneath," "above," "over," and the like, may be used herein for ease of description to describe one element or feature's relationship to another element or feature as illustrated. Spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The device may have other orientations (rotated 90 degrees or at other orientations), and the spatially relative descriptors used herein interpreted accordingly.

It should be noted that in this document, relational terms such as "first" and "second" and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.

Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present application, and not for limiting the same; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims (12)

1. A single cell, characterized by comprising:

a battery cell (1) having a tab (11);

a top cover (2) provided with through holes (21) and terminal holes (22) which are arranged at intervals; and

a terminal member (4), wherein a part of the terminal member (4) is penetrated through the top cover from the terminal hole (22),

the terminal piece (4) comprises a first terminal part (41), the first terminal part (41) is located between the top cover (2) and the tab (11), the first terminal part (41) is fixedly welded with the tab (11), and the through hole (21) is used for enabling the first terminal part (41) and the tab (11) to be welded.

2. The cell according to claim 1, wherein the first terminal portion (41) has a welding zone (411), an orthographic projection of the welding zone (411) on the cell (1) is located on the tab (11) along a first direction Z, and an orthographic projection of the through hole (21) on the first terminal portion (41) is located at least partially on the welding zone (411).

3. The unit cell according to claim 2, wherein in the front projection of the top cover (2) onto the battery cell (1), the through hole (21) has a first area S1, the welding region (411) has a second area S2, S2 < S1, the first terminal portion (41) has a third area S3, S2 is less than or equal to 30% ×s3, wherein the first area S1 is a cross-sectional area of a surface of the through hole (21) in the first direction X and the third direction Y, the third area S3 is a projected area of the first terminal portion (41) toward the tab (11) side in the first direction X and the third direction Y, and the second area S2 is an area enclosed by a welding track on the welding region (411).

4. The unit cell according to claim 2, characterized in that the first terminal portion (41) has a thickness of not more than 3mm in the first direction Z.

5. The unit cell according to claim 2, characterized in that the terminal member (4) further comprises a second terminal portion (42) connected to the first terminal portion (41), the second terminal portion (42) being electrically or insulatively connected to the top cover (2) through the terminal hole (22).

6. The unit cell according to claim 5, wherein the first terminal portion (41) is a terminal plate having a plate-like structure,

and one end of the terminal plate is provided with the welding area (411) along a second direction X, the other end of the terminal plate is connected with the second terminal part (42), and the first direction Z is intersected with the second direction X.

7. The unit cell according to any one of claims 1-6, further comprising an insulating member (5) located between said first terminal portion (41) and said top cover (2).

8. The unit cell according to any one of claims 1-6, further comprising an explosion-proof valve (7), said explosion-proof valve (7) being provided in said through hole (21).

9. The unit cell according to any one of claims 1 to 6, further comprising a sealing portion (6) provided in said through hole (21) for sealing said through hole (21).

10. The unit cell according to claim 9, further comprising a liquid filling hole (23), the liquid filling hole (23) being provided in the sealing portion (6).

11. The cell according to claim 9, wherein the sealing part (6) has a first thickness d1 in the first direction Z, the top cover (2) has a second thickness d2, d1 < d2, and d2 < 10mm.

12. A battery module comprising the unit cell (100) according to any one of claims 1 to 11.