CN212085154U

CN212085154U - Lithium ion battery, battery core and vehicle

Info

Publication number: CN212085154U
Application number: CN202020964580.7U
Authority: CN
Inventors: 路宇帅
Original assignee: Svolt Energy Technology Co Ltd
Current assignee: Svolt Energy Technology Co Ltd
Priority date: 2020-05-29
Filing date: 2020-05-29
Publication date: 2020-12-04
Anticipated expiration: 2030-05-29

Abstract

The utility model relates to a lithium ion battery and electric core, vehicle thereof, electric core is including positive plate (1), diaphragm (2) and negative pole piece (3) that range upon range of setting in proper order, positive plate is connected with the one end of positive tab (10) and the negative pole piece is connected with the relative setting of one end of negative pole ear (30), and the thickness that negative pole ear's one end was kept away from to the negative pole piece is less than the thickness that positive plate is connected with the one end of positive tab. When this electric core that openly provides carries out the design, the impedance of considering the pole piece not only is relevant with pole piece length, still is relevant with pole piece thickness, the pole piece is thicker, lithium ion diffusion distance is longer more, the impedance is bigger, on the contrary, the pole piece is thinner, the impedance is smaller, design through the thickness of adjusting positive pole piece and negative pole piece, can compensate or alleviate the inconsistent problem of impedance because the increase of pole piece length leads to, the one end of keeping away from the negative pole ear of negative pole piece appears analyzing lithium short circuit problem under the circumstances of avoiding heavy current charging, the extension battery life, promote the security of battery.

Description

Lithium ion battery, battery core and vehicle

Technical Field

The disclosure relates to the field of energy storage devices, in particular to a lithium ion battery and an electric core and a vehicle thereof.

Background

Compared with the traditional automobile, the battery has short endurance mileage and long charging time, which are important reasons for restricting the development of new energy automobiles. In the related art, in order to increase the endurance mileage of the battery, the battery core is made into an ultra-long battery core which is directly and transversely arranged inside the battery pack, so that the space utilization rate of the battery pack is improved, and the cost is reduced.

However, although the volume energy density of the battery pack can be remarkably improved after the size of the battery cell is increased, particularly the length of the battery cell is increased, the internal resistance of the battery is increased due to the direct proportion relation between the internal resistance and the length, so that the problems of reduction of the charge-discharge rate of the battery cell, increase of the temperature and the like are caused; in addition, the tail end (the end far away from the negative electrode tab) of the negative electrode tab is an area with the highest impedance of the negative electrode tab and corresponds to an area where the positive electrode tab of the adjacent positive electrode tab is located (an area with the lowest impedance of the positive electrode tab), and in the charging process of the battery, because the area with the highest impedance of the negative electrode tab corresponds to the area with the lowest impedance of the positive electrode tab, the potential of the negative electrode to Li is reduced quickly in the charging process, and particularly lithium dendrites are easily generated at the tail end of the negative electrode tab in the high-rate charging process, so that great potential safety.

SUMMERY OF THE UTILITY MODEL

A first object of the present disclosure is to provide a battery cell of a lithium ion battery, which can solve the problems of impedance unevenness, lithium precipitation at the end of a negative electrode plate, and the like caused by increasing the length of the electrode plate.

A second object of the present disclosure is to provide a lithium ion battery using the battery cell provided by the present disclosure.

A third object of the present disclosure is to provide a vehicle using the lithium ion battery provided by the present disclosure.

In order to realize the above-mentioned purpose, this disclosure provides a lithium ion battery's electric core, including positive plate, diaphragm and the negative pole piece that stacks gradually the setting, the positive plate be connected with the one end of anodal ear with the negative pole piece is connected with the relative setting of one end of negative pole ear, and the negative pole piece is kept away from the thickness of the one end of negative pole ear is less than the positive plate is connected with the thickness of the one end of anodal ear.

Optionally, the positive plate is connected with the one end of positive tab is positive plate first end, keeps away from the one end of positive tab is positive plate second end, the negative plate is connected with the one end of negative tab is negative plate first end, keeps away from the one end of negative tab is negative plate second end, the positive plate is followed positive plate first end is to positive plate second end thickness reduces gradually, and/or the negative plate is followed negative plate first end is to negative plate second end thickness reduces gradually.

Optionally, the positive tab comprises a positive membrane layer filled with a first active material, and the positive tab protrudes from and is electrically connected to the positive membrane layer.

Optionally, the negative electrode sheet comprises a negative electrode membrane layer filled with a second active material, and the negative electrode tab extends out of the negative electrode membrane layer and is electrically connected with the negative electrode membrane layer.

Optionally, the length of the positive plate and the negative plate is greater than 500mm, and the width of the positive plate and the negative plate is 80-120 mm.

Optionally, the battery cell is a winding battery cell.

Optionally, the widths of the positive tab and the positive plate are the same, and/or the widths of the negative tab and the negative plate are the same.

According to a second aspect of the present disclosure, there is also provided a lithium ion battery, including a battery cell, where the battery cell is the battery cell of the lithium ion battery.

According to a third aspect of the present disclosure, there is also provided a vehicle, including a power battery, where the power battery is the above lithium ion battery.

Through the technical scheme, when the electric core that this disclosure provided is designed, consider that the impedance of pole piece is not only relevant with pole piece length, still relevant with pole piece thickness, the pole piece is thicker, lithium ion diffusion distance is longer more, the impedance is big more, on the contrary, the pole piece is thinner, the impedance is little, design through the thickness to positive pole piece and negative pole piece, can compensate or alleviate the inconsistent problem of impedance because pole piece length increases leads to, avoid under the heavy current charging condition negative pole piece to keep away from the one end of negative pole ear and appear analyzing lithium short circuit problem, prolong battery life, promote the security of battery.

Additional features and advantages of the disclosure will be set forth in the detailed description which follows.

Drawings

The accompanying drawings, which are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this specification, illustrate embodiments of the disclosure and together with the description serve to explain the disclosure without limiting the disclosure. In the drawings:

fig. 1 is a top view of a cell of a prior art lithium ion battery;

fig. 2 is a top view of a cell of a lithium ion battery provided in an exemplary embodiment of the present disclosure;

fig. 3 is a cross-sectional view of a cell of a prior art lithium ion battery;

fig. 4 is a cross-sectional view of a cell of a lithium ion battery provided in an exemplary embodiment of the present disclosure.

Description of the reference numerals

1-positive plate, 10-positive tab, 100-positive membrane sheet, 11-positive plate first end, 12-positive plate second end, 2-diaphragm, 3-negative plate, 30-negative tab, 300-negative membrane sheet, 31-negative plate first end, 32-negative plate second end.

Detailed Description

The following detailed description of specific embodiments of the present disclosure is provided in connection with the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating the present disclosure, are given by way of illustration and explanation only, not limitation.

In the present disclosure, the use of directional terms such as "inner" and "outer" in the absence of a contrary indication means that the corresponding parts are inner and outer in profile, and furthermore, the use of the terms "first", "second", and the like in the present disclosure is intended to distinguish one element from another without order or importance. In addition, when the following description refers to the accompanying drawings, like numbers in different drawings represent the same or similar elements, unless otherwise indicated.

As shown in fig. 1, in order to increase the endurance mileage of the battery, in the existing cell design, the module is directly cancelled, and an ultra-long cell is made, however, since the internal resistance of the battery is in direct proportion to the length of the pole piece, that is, the longer the length of the pole piece is, the greater the internal resistance of the battery is, the problems of decreased charge-discharge rate of the cell, increased temperature, and the like are caused.

In order to solve the above problem, as shown in fig. 2, the tabs are disposed at two ends of the pole piece, and the width of the tabs is increased to be equal to the width of the pole piece, for example, the width of the positive pole tab 10 is equal to the width of the positive pole piece 1, and the width of the negative pole tab 30 is equal to the width of the negative pole piece 3, which may be called a full-tab cell structure.

Further, as shown in fig. 3, the electric core of the lithium battery includes a positive plate 1, a diaphragm 2 and a negative plate 3, which are sequentially stacked, wherein the one end of the positive plate 1 connected with the positive tab 10 and the one end of the negative plate 3 connected with the negative tab 30 are oppositely disposed, and for convenience of description, the one end of the positive plate 1 connected with the positive tab 10 is a positive plate first end 11, the one end far away from the positive tab 10 is a positive plate second end 12, the one end of the negative plate 3 connected with the negative tab 30 is a negative plate first end 31, and the one end far away from the negative tab 30 is a negative plate second end 32. For the electric core structure of the tabs from the two ends, the second end 32 of the negative pole piece (the highest impedance area of the negative pole piece) just corresponds to the first end 11 of the positive pole piece (the lowest impedance area of the positive pole piece), and in the charging process, the part with high impedance of the negative pole piece just corresponds to the part with low impedance of the positive pole piece, so that the potential of the negative pole to Li is rapidly reduced in the charging process, lithium dendrites are easily generated at the second end 12 of the negative pole piece, the battery is short-circuited, and great potential safety hazards are caused.

In view of the above problem, in the battery cell of the lithium ion battery provided by the present disclosure, as shown in fig. 4, the thickness of the end of the negative electrode tab 3 away from the negative electrode tab 30 (i.e., the negative electrode tab second end 32) is smaller than the thickness of the end of the positive electrode tab 1 connected with the positive electrode tab 10 (i.e., the positive electrode tab first end 11).

Considering that the impedance of the pole piece is not only related to the length of the pole piece, but also related to the thickness of the pole piece, the thicker the pole piece is, the longer the diffusion distance of lithium ions is, the larger the impedance is, conversely, the thinner the pole piece is, the smaller the impedance is, by designing the thicknesses of the first end 11 of the pole piece and the second end 32 of the negative pole piece, the problem of inconsistent impedance caused by the increase of the length of the pole piece can be made up or relieved, the problem of lithium short circuit caused by the lithium precipitation of the second end 32 of the negative pole piece under the condition of large-current charging is avoided, the service.

Specifically, in the present embodiment, as shown in fig. 4, the thickness of the positive electrode tab 1 gradually decreases from the first end 11 of the positive electrode tab to the second end 12 of the positive electrode tab, and/or the thickness of the negative electrode tab 3 gradually decreases from the first end 31 of the negative electrode tab to the second end 32 of the negative electrode tab, i.e., the thickness a of the first end 31 of the negative electrode tab is greater than the thickness b of the second end 32 of the negative electrode tab. In the embodiment, the thicknesses of the positive plate 1 and the negative plate 3 are gradually and linearly increased, and a certain matching degree is formed between the thicknesses and the internal resistance caused by the length of the positive plate and the internal resistance of the negative plate, so that the internal resistance of each area of the positive plate is uniformly distributed in the charge and discharge process of the positive plate, and the problems of local heat generation and lithium precipitation in high-rate charge are avoided. In other embodiments, it is also considered that only the thickness of the first end 11 of the positive electrode sheet and the second end 32 of the negative electrode sheet is increased or decreased, and both are within the protection scope of the present disclosure.

In the present disclosure, the positive electrode sheet 1 is designed by using the principle that the internal resistances of the length and thickness of the negative electrode sheet 3 match each other at the same time. The second end 12 of the positive plate is a region with higher impedance of the positive plate, the second end 12 of the positive plate is properly thinned, the first end 11 of the positive plate is a region with lower impedance of the positive plate, the first end 11 of the positive plate is properly thickened to be matched with internal resistance caused by the length of the positive plate, and the internal resistance of all the regions is uniform and consistent.

Specifically, in the present disclosure, as shown in fig. 4, positive electrode tab 1 includes positive electrode membrane layer 100 filled with a first active material, and positive electrode tab 10 protrudes from inside positive electrode membrane layer 100 and is electrically connected to positive electrode membrane layer 100. The first active material may be lithium cobalt oxide or the like. Likewise, the negative electrode tab 3 includes a negative electrode film layer 300 filled with a second active material, the negative electrode tab 30 extends from the inside of the negative electrode film layer 300 and is electrically connected to the negative electrode film layer 300, and the second active material may be graphite or the like. Regarding the area where the positive electrode tab 10 is electrically connected to the positive electrode film layer 100, the area where the negative electrode tab 30 is electrically connected to the negative electrode film layer 300 depends on the sizes of the positive electrode tab 10 and the negative electrode tab 30, and may be at most equal to the size of the corresponding film layer.

The electric core that this disclosure provided can be coiling formula electric core or tiling electric core etc..

According to a second aspect of the present disclosure, a lithium ion battery is further provided, including an electric core, the electric core may be the electric core of the lithium ion battery described above, the problem of internal resistance mismatch between the first end 11 of the positive plate and the second end 32 of the negative plate can be improved, heating of the pole pieces is reduced, impedance matching between the positive and negative pole pieces is balanced, lithium precipitation by the negative pole is avoided, and the safety performance of the battery is improved. In addition, the battery case may be a soft bag or an aluminum case, and the like, all belong to the protection scope of the present disclosure.

According to a third aspect of the present disclosure, there is also provided a vehicle, including a power battery, where the power battery is the above lithium ion battery. The vehicle has all the beneficial effects of the lithium ion battery and the battery core, redundant description is not needed here, the battery can improve the endurance mileage of the vehicle, and the charge-discharge multiplying power of the battery is obviously improved.

The preferred embodiments of the present disclosure are described in detail with reference to the accompanying drawings, however, the present disclosure is not limited to the specific details of the above embodiments, and various simple modifications may be made to the technical solution of the present disclosure within the technical idea of the present disclosure, and these simple modifications all belong to the protection scope of the present disclosure.

It should be noted that the various features described in the above embodiments may be combined in any suitable manner without departing from the scope of the invention. In order to avoid unnecessary repetition, various possible combinations will not be separately described in this disclosure.

In addition, any combination of various embodiments of the present disclosure may be made, and the same should be considered as the disclosure of the present disclosure, as long as it does not depart from the spirit of the present disclosure.

Claims

1. The utility model provides a lithium ion battery's electric core, includes positive plate (1), diaphragm (2) and negative pole piece (3) that stack gradually the setting, its characterized in that, positive plate (1) be connected with the one end of positive tab (10) and negative pole piece (3) are connected with the relative setting of one end of negative pole ear (30), and keep away from negative pole piece (3) the thickness of the one end of negative pole ear (30) is less than positive plate (1) is connected with the thickness of the one end of positive tab (10).

2. The battery cell of the lithium ion battery according to claim 1, wherein the end of the positive electrode tab (1) connected to the positive electrode tab (10) is a positive electrode tab first end (11), the end away from the positive electrode tab (10) is a positive electrode tab second end (12), the end of the negative electrode tab (3) connected to the negative electrode tab (30) is a negative electrode tab first end (31), the end away from the negative electrode tab (30) is a negative electrode tab second end (32), the thickness of the positive electrode tab (1) decreases gradually from the positive electrode tab first end (11) to the positive electrode tab second end (12), and/or the thickness of the negative electrode tab (3) decreases gradually from the negative electrode tab first end (31) to the negative electrode tab second end (32).

3. The battery cell of the lithium ion battery according to claim 1, wherein the positive electrode sheet (1) comprises a positive electrode membrane sheet layer (100) filled with a first active material, and the positive electrode tab (10) extends from the inside of the positive electrode membrane sheet layer (100) and is electrically connected with the positive electrode membrane sheet layer (100).

4. The battery cell of the lithium ion battery according to claim 1, wherein the negative electrode tab (3) comprises a negative electrode membrane layer (300) filled with a second active material, and the negative electrode tab (30) protrudes from the inside of the negative electrode membrane layer (300) and is electrically connected with the negative electrode membrane layer (300).

5. The battery cell of the lithium ion battery according to claim 1, wherein the positive electrode sheet (1) and the negative electrode sheet (3) have a length of more than 500mm and a width of 80-120 mm.

6. The cell of claim 1, wherein the cell is a wound cell.

7. The cell of the lithium ion battery according to any of claims 1 to 6, wherein the positive tab (10) and the positive tab (1) have the same width, and/or the negative tab (30) and the negative tab (3) have the same width.

8. A lithium ion battery comprising a cell, characterized in that the cell is a cell of a lithium ion battery according to any of claims 1-7.

9. A vehicle comprising a power battery, characterized in that the power battery is the lithium ion battery according to claim 8.