CN105762322A - Secondary battery - Google Patents

Abstract

The present application relates to the field of energy storage devices, in particular to a secondary battery, including a bare cell, a top cover, a first pole, a second pole, a first lead, and a second lead, and the top cover is located on the bare cell Above the top, the first pole and the second pole are respectively arranged at both ends of the top cover, and the bare cell is shared by the first pole piece, the second pole piece and the diaphragm between the first pole piece and the second pole piece. Formed by winding, the first pole piece has a first coated part and a plurality of first uncoated parts, a first gap is left between two adjacent first uncoated parts, and the first pole piece in the bare cell Bending at the first gap, all the first uncoated parts are arranged along the thickness direction of the bare cell to form the first tab, and the end of the first tab is bent toward the thickness direction of the bare cell to form the first connection end, and stick to the first pin, and the first pin is connected to the first pole. The secondary battery provided by this embodiment can increase the energy density of the battery.

Description

secondary battery

technical field

The present application relates to the field of energy storage devices, in particular to a secondary battery.

Background technique

At present, due to the advantages of high energy density, high power density, many cycle times, and long storage time, lithium-ion batteries are widely used in portable electronic devices such as mobile phones, digital cameras, and laptop computers, and are used in electric vehicles, Electric vehicles such as electric bicycles and large and medium-sized electric equipment such as energy storage facilities have broad application prospects, and become the key to solving global problems such as energy crisis and environmental pollution.

In the related art, the tab-side-out battery is formed by winding a positive electrode sheet, a separator, and a negative electrode sheet. Among them, the positive and negative electrode pieces are divided into coated parts and uncoated parts; the coated part is coated with active materials, and the uncoated part is electrically connected to the pole through the top cover connecting plate, so as to realize the transmission of the current inside the battery to the battery. external. Since the positive and negative electrodes are coated with active materials, the thickness of the coated part is greater than that of the uncoated part. When the winding is formed, in the free state, there is a certain gap between the uncoated parts of each coil.

In order to connect the battery to the pole, the uncoated part of the pole piece is usually compressed during the connection. During the compression process, there will be a certain misalignment of the tab from the outer ring of the tab to the inner ring of the tab. , the size of the dislocation is related to the thickness of the tab. Generally, in order to ensure that all the tabs are effectively connected to the pins, the connection part is located in the overlapping area of all the tabs, while the outer part of the overlapping area is not used. This area occupies part of the space of the battery, resulting in a decrease in the space utilization of the battery. , the energy density of the battery is affected. Generally, if the tabs in the arc area of the tabs are also pressed and assembled, the coating part inside the area is easily damaged, causing the coated active material to fall off, and the active material falling off will form particles inside the battery It will affect the performance of the battery, and even seriously cause the safety risk of internal short circuit of the battery.

Contents of the invention

The present application provides a secondary battery, which can effectively improve the energy density of the battery.

The secondary battery provided by this application includes a bare cell, a top cover, a first pole, a second pole, a first pin and a second pin,

The top cover is located above the bare cell, the first pole and the second pole are respectively arranged at both ends of the top cover, and the bare cell consists of a first pole piece, a second The pole piece and the diaphragm located between the first pole piece and the second pole piece are wound together to form,

The first pole piece has a first coated portion coated with a first active material and a plurality of first uncoated portions where the first active material does not exist, and the plurality of first uncoated portions are distributed stacked on one side of the first coating part and along the thickness direction of the bare cell,

All the first uncoated parts form a first tab, and the first tab is bent toward the thickness direction of the bare cell to form a first connection end, and the first connection end is connected to the first lead. pin fit, the first pin is connected to the first pole,

The second pole piece forms a second tab on a side of the bare cell away from the first tab, and the second tab is connected to the second pole through the second pin.

Preferably, all the first uncoated parts are bent from one side in the thickness direction of the bare cell to form one first tab.

Preferably, the first pin is bonded to the side of the first connection terminal away from the bare cell.

Preferably, the first pin is bonded to the side of the first connection end facing the bare cell.

Preferably, all the first uncoated parts form two first tabs, and the two first tabs are respectively bent from both sides in the thickness direction of the bare cell to the middle. The first connecting end, the two first connecting ends and the first pin are bonded and connected in sequence.

Preferably, the two first tabs form a ring, and the first pin is located in the ring.

Preferably, the second pole piece has a second coated portion coated with a second active material and a plurality of second uncoated portions in which the second active material does not exist, and a plurality of the second uncoated portions The coated part is distributed on one side of the second coated part and stacked along the thickness direction of the bare cell, and all the second uncoated parts are located on the side of the bare cell away from the first tab ,

All the second uncoated parts form the second tab, and the second tab is bent toward the thickness direction of the bare cell to form a second connection end, and is bonded to the second pin , the second pin is connected to the second pole.

Preferably, the first tab and the second tab are arranged symmetrically.

Preferably, the first tab and/or the second tab are located on the upper part of the bare cell.

Preferably, the first tab is welded to the first pin by ultrasonic welding or resistance welding.

The technical solution provided by the application can achieve the following beneficial effects:

The secondary battery provided by the present application can at least ensure that there is no partial overlapping area on one side of the bare cell after winding to form the bare cell, and can bend the tab on this side, thereby reducing the occupied area of the tab. The space increases the energy density of the battery.

It is to be understood that both the foregoing general description and the following detailed description are exemplary only and are not restrictive of the application.

Description of drawings

FIG. 1 is a schematic diagram of the overall structure of a secondary battery provided in an embodiment of the present application;

FIG. 2 is a schematic structural diagram of a bare cell provided in an embodiment of the present application;

FIG. 3 is a schematic bottom view of the secondary battery provided by the embodiment of the present application;

4-6 are partially enlarged schematic diagrams of part A in FIG. 3 corresponding to secondary batteries with different structures provided in this embodiment.

Reference signs:

10-bare cell;

100-the first lug; 100’-the second lug;

102 - the first connection end;

20 - top cover;

30-the first pole; 30'-the second pole;

40-the first pin; 40-the second pin.

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the application and together with the description serve to explain the principles of the application.

detailed description

The present application will be described in further detail below through specific embodiments and in conjunction with the accompanying drawings. The terms "front", "rear", "left", "right", "upper" and "lower" mentioned in the text refer to the placed state of the secondary battery in the drawings.

As shown in FIG. 1 , the embodiment of the present application provides a bare cell 10 , a top cover 20 , a first pole 30 , a second pole 30 ′, a first pin 40 and a second pin 40 ′, The top cover 20 is located above the bare cell 10 , and the first pole 30 and the second pole 30 ′ are respectively disposed at two ends of the top cover 20 . The bare cell 10 provided in this embodiment is a lug side-out type bare cell (that is, the positive and negative tabs protrude from both ends of the bare cell 10), specifically, the bare cell 10 consists of a first pole piece (not shown in the figure), the second pole piece (not shown in the figure), and the diaphragm (not shown in the figure) located between the first pole piece and the second pole piece are formed by winding together. Wherein, the first pole piece may be a positive pole piece or a negative pole piece, without any limitation. At the same time, the polarity of the first pole piece is opposite to that of the second pole piece. Correspondingly, the first active material may be a positive electrode active material (such as lithium cobaltate, lithium iron phosphate), or a negative electrode active material (such as carbon, silicon). Meanwhile, the second active material can be a negative active material or a positive active material accordingly.

The first pole piece has a first coated portion coated with a first active material and a plurality of first uncoated portions where the first active material does not exist, wherein the first coated portion is used to generate electrical energy, and the first uncoated portion The coated part is used to transmit electrical energy. A plurality of first uncoated portions are distributed on one side of the first coated portion. Moreover, in the bare electric core 10 formed by winding, all the first uncoated parts in this embodiment are located on one side of the bare electric core 10, and are arranged along the thickness direction of the bare electric core 10, thereby forming a bare electric core 10. The first tab 100 of the battery cell 10 . However, in the prior art, the upper and lower corners of the bare cell 10 , and the part used to form a partial overlapping area is removed in this embodiment.

In this embodiment, there are mainly two ways to form the first uncoated part. The first one is to adopt the same first pole piece structure as the prior art, that is, to leave Take a complete uncoated part, and then wind it to form a bare cell. After the winding is completed, the uncoated part will form a helical structure. At this time, this helical structure corresponds to the upper and lower parts of the bare cell 10. The part at the corner is completely cut off, and the remaining part forms the first uncoated part.

The second method is to cut off a part at intervals on the complete uncoated part before winding, and the remaining part becomes the first uncoated part, and the part between two adjacent first uncoated parts The cut-off part between them forms the first gap, and it is particularly important to grasp the interval of the first gap. As shown in FIG. 2 , in the bare cell 10 formed by winding, the first pole piece needs to be bent at each first gap, so as to avoid forming a partial overlapping area. And all the first uncoated parts are located on one side of the bare cell 10 and arranged along the thickness direction of the bare cell 10 , thereby forming the first tab 100 of the bare cell 10 .

At this time, the first tab 100 can be clamped, bent, etc., because it is not constrained by the partial overlapping area. Moreover, in these two ways, these first uncoated parts do not have to completely overlap, as long as the subsequent processing is not affected, a small amount of staggering in the height direction of the bare cell 10 is also allowed.

In this embodiment, the end of the first tab 100 is bent toward the thickness direction of the bare cell 10 to form the first connection end 102, and is attached to the first pin 40, and the first pin 40 is in turn It is connected with the first pole 30 so as to realize electrical conduction between the first pole 30 and the first pole piece. The bent first tab 100 can greatly reduce the space occupied by the bare cell 10 in the longitudinal direction, thus improving the energy density of the secondary battery.

In this embodiment, all the first uncoated parts may form one first tab 100 (see FIGS. 4 and 5 ), or may form two first tabs 100 (see FIG. 6 ). When only one first tab 100 is formed, all the first uncoated parts can be gathered on one side in the thickness direction of the bare cell 10 to form a pair of tabs 100, and then the end or middle of the first tab 100 Bending toward the other side in the thickness direction of the bare electric core, the first pin 40 can be attached to the side of the first connecting end 102 formed by bending the first tab 100 away from the bare electric core 10 (as shown in FIG. 4 As shown), it can also be attached to the side of the first connecting end 102 facing the bare cell 10 (as shown in FIG. 5 ). When the first uncoated part forms two first tabs 100 at the same time, the two first tabs 100 are respectively bent from both sides in the thickness direction of the bare cell 10 to the middle to form a first connection end 102, and the two first tabs 100 The first connecting end 102 and the first pin 40 are sequentially pasted together for connection. For example, the first pin 40 is positioned outside the two first connection ends 102 , or the first pin 40 is positioned between the two first connection ends 102 . However, the most preferred connection method is to stack the two first connection ends 102 so that the two first tabs 100 form a ring, and the first pin 40 is located inside the ring and is connected to the first connection. end 102 (as shown in Figure 6). In this way, the space in the length direction occupied by the tab connection structure can be reduced to the greatest extent. The connection between the first connection end 102 and the first pin 40 may be performed by means of ultrasonic welding or resistance welding.

Conventional connection structure and connection method can be adopted between the second pole piece and the second pin 40' in this embodiment. Of course, if the structure identical to that of the first pole piece and the first pin 40 is adopted, the effect will be improved. better. Specifically, the second pole piece has a second coated portion coated with a second active material and a plurality of second uncoated portions in which the second active material does not exist, and the plurality of second uncoated portions are distributed on One side of the second coated part, and there is a second gap between two adjacent second uncoated parts, in the bare electric core 10 formed by winding, the second pole piece is bent at the second gap , and all the second uncoated parts are located on the side of the bare cell 10 away from the first tab 100 (see FIG. 2 ), and are arranged along the thickness direction of the bare cell 10 . All the second uncoated parts form the second tab 102, and the end of the second tab 100' is bent toward the thickness direction of the bare electric core 10 to form a second connection end (not shown in the figure), and is connected with the second The pin 40' is attached to and connected with the second pole 30' through the second pin 40'.

The first tab 100 and the second tab 100' are preferably arranged symmetrically to simplify the structure and facilitate processing. Moreover, since the bare cell 10 in this embodiment is a side-out structure, in order to facilitate the connection of the first pin 40 and the second pin 40' with the first tab 100 and the second tab 100', it is possible to The positions of the first tab 100 and the second tab 100 ′ are set as far as possible on the upper part of the bare cell 10 , that is, near the top cover 20 .

The secondary battery provided by this embodiment can ensure that there is no partial overlapping area of the bare cell 10, and can bend the first tab 100 and the second tab 100', thereby reducing the thickness of the first tab 100 and the second tab. The space occupied by the tab 100' improves the energy density of the battery.

The above descriptions are only preferred embodiments of the present application, and are not intended to limit the present application. For those skilled in the art, there may be various modifications and changes in the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of this application shall be included within the protection scope of this application.

Claims (10)

1. a secondary cell, it is characterised in that include naked battery core, top cover, the first pole, the second pole, the first pin and the second pin,

Described top cover is positioned at the top of described naked battery core, described first pole and described second pole are separately positioned on the two ends of described top cover, described naked battery core is formed together about volume by the first pole piece, the second pole piece and the barrier film between described first pole piece and described second pole piece

Described first pole piece has the first coated portion being coated with the first active substance and multiple the first uncoated part being absent from described first active substance, multiple described first uncoated parts are distributed in the side of described first coated portion and along described naked battery core thickness direction stacking, all described first uncoated parts form the first lug, described first lug is bent to form the first link towards the thickness direction of described naked battery core, described first link and described first pin laminating, described first pin is connected with described first pole

Described second pole piece forms the second lug in described naked battery core away from the side of described first lug, and described second lug is connected with described second pole by described second pin.

2. secondary cell according to claim 1, it is characterised in that all described first uncoated parts are bent to form described first lug from the side of the thickness direction of described naked battery core.

3. secondary cell according to claim 2, it is characterised in that described first pin is fitted and connected away from the side of described naked battery core with described first link.

4. secondary cell according to claim 2, it is characterised in that described first pin is fitted and connected towards the side of described naked battery core with described first link.

5. secondary cell according to claim 1, it is characterized in that, all described first uncoated parts form two described first lugs, and two described first lugs are bent to form described first link from the two of the thickness direction of described naked battery core lateral middle parts respectively, two described first links and described first pin three are fitted and connected successively.

6. secondary cell according to claim 5, it is characterised in that two described first lugs surround ring-type, and described first pin is positioned at ring.

7. the secondary cell according to any one of claim 1 to 6, it is characterized in that, described second pole piece has the second coated portion being coated with the second active substance and multiple the second uncoated part being absent from described second active substance, multiple described second uncoated parts are distributed in the side of described second coated portion and along described naked battery core thickness direction stacking, all described second uncoated parts are positioned at the described naked battery core side away from described first lug

All described second uncoated parts form described second lug, and described second lug is bent to form the second link towards the thickness direction of described naked battery core, and fits with described second pin, and described second pin is connected with described second pole.

8. secondary cell according to claim 7, it is characterised in that described first lug and described second lug are symmetrical arranged.

9. the secondary cell according to any one of claim 1 to 6, it is characterised in that described first lug and/or described second lug are positioned at the top of described naked battery core.

10. the secondary cell according to any one of claim 1 to 6, it is characterised in that described first lug and described first pin are by ultrasonic bonding or resistance welding.