CN212907831U

CN212907831U - Lithium ion battery

Info

Publication number: CN212907831U
Application number: CN202022009322.6U
Authority: CN
Inventors: 许岩; 彭冲; 李俊义; 徐延铭
Original assignee: Zhuhai Cosmx Battery Co Ltd
Current assignee: Zhuhai Cosmx Battery Co Ltd
Priority date: 2020-09-15
Filing date: 2020-09-15
Publication date: 2021-04-06
Anticipated expiration: 2030-09-15

Abstract

The utility model provides a lithium ion battery, includes the book core body that is formed by positive plate, negative pole piece and diaphragm coiling, positive foil electrode lug has been drawn forth on the foil of positive plate, negative foil electrode lug has been drawn forth on the foil of negative plate, the quantity of negative foil electrode lug is greater than the quantity of positive foil electrode lug, just the quantity a of negative foil electrode lug with the relation between the quantity b of positive foil electrode lug is: when a is less than or equal to (n +1)/2, b is less than or equal to 6a/7 and more than or equal to 2, and a + b is less than or equal to n; when (n +1)/2 is more than a and less than or equal to n, b is more than or equal to a/7 and less than or equal to 4a/7 and b is more than or equal to 3, and a + b is more than or equal to n +2 and less than or equal to 1.5 n. The utility model discloses an optimize just, the quantity of the foil utmost point ear of drawing forth on the negative pole piece foil, make anodal lithium speed of taking off and negative pole inlay lithium speed phase-match, reduce because the condition emergence that the negative pole easily analyzed lithium when speed between them unmatched and leaded to quick charge, reach the long cycle life's of extension multi-tab battery purpose.

Description

Lithium ion battery

Technical Field

The utility model belongs to the technical field of lithium ion battery, more specifically say, relate to a type of charging lithium ion battery soon.

Background

In order to meet the use requirements of people, various battery manufacturers are always researching and developing a quick charging technology for lithium ion batteries. Batteries using high rate charging technology have a somewhat lower volumetric energy density than batteries with conventional charging rates. However, with the advent of the 5G era, the energy density requirements of users on fast-charging lithium ion batteries are also higher and higher. In some high-rate or ultrahigh-rate rechargeable batteries, a multi-tab structure can be used, and compared with a conventional positive-pole and negative-pole single-tab leading-out structure, a multi-tab winding core leads out a plurality of foil tabs on a pole piece, the wound foil tabs form a lamination, and then metal tabs are welded on the foil tab lamination to form a positive tab or a negative tab of the battery. For example, in a multi-tab winding core, an aluminum foil is used as a positive electrode foil, a positive electrode foil tab and the aluminum foil are of an integrated structure, a plurality of aluminum foil tabs are stacked after winding, the aluminum tabs are welded on the aluminum foil stack to form a positive electrode tab, correspondingly, a copper foil is used as a negative electrode foil, a plurality of copper foil tabs are stacked after winding, and a nickel tab or a copper nickel-plated tab is welded on the copper foil stack to form a negative electrode tab.

Fig. 1 is a schematic structural diagram of a conventional multi-tab winding core, which includes a positive plate 102, a negative plate 101, and a separator 103, wherein the positive plate is coated with a positive paste layer, and the negative plate is coated with a negative paste layer. A positive foil tab 102a is led out from the positive foil, a negative foil tab 101a is led out from the negative foil, and usually one tab is led out when the pole pieces are wound for one or half turns, generally, when the number of the positive foil tabs is M, the number of the negative foil tabs is M or M ± 1 or M ± 2 (fig. 1 simply shows 4 pairs of tabs, and not all layers of the winding core and all tabs are drawn). In order to improve the energy density of the battery with the multi-tab structure, the coating surface density of the pole piece is high, or the compaction density of the pole piece is high, so that the lithium removal speed of the positive electrode is not matched with the lithium insertion speed of the negative electrode during charging, and the lithium precipitation phenomenon of the negative electrode is easy to generate.

SUMMERY OF THE UTILITY MODEL

The utility model aims at providing a can improve the circulation constant current and fill the lithium ion battery who has the multiple tab structure that compares, can reduce the negative pole when charging and analyse lithium phenomenon.

In order to achieve the above object, the present invention adopts the following technical solutions:

the utility model provides a lithium ion battery, includes the book core body that is formed by positive plate, negative pole piece and diaphragm coiling, positive foil electrode lug has been drawn forth on the foil of positive plate, negative foil electrode lug has been drawn forth on the foil of negative plate, the quantity of negative foil electrode lug is greater than the quantity of positive foil electrode lug, just the quantity a of negative foil electrode lug with the relation between the quantity b of positive foil electrode lug is:

when a is less than or equal to (n +1)/2, b is less than or equal to 6a/7 and more than or equal to 2, and a + b is less than or equal to n;

when (n +1)/2 is more than a and less than or equal to n, b is more than or equal to a/7 and less than or equal to 4a/7 and b is more than or equal to 3, and a + b is more than or equal to n +2 and less than or equal to 1.5 n;

wherein n represents the folding number of the negative electrode sheet in the winding core body, a is less than or equal to n, and b is less than or equal to n.

Further, the number of turns of negative pole piece is more than 7 in rolling up the core body, it has more than 1 negative pole foil utmost point ear and more than 1 positive pole foil utmost point ear to roll up the core body.

More specifically, the winding core body is of an aluminum foil wrapping structure, and the number of folds of the positive plate is the same as that of folds of the negative plate; or the winding core body is of a diaphragm wrapping structure, and the number of folds of the positive plate is 2 folds less than that of the negative plate.

More specifically, the fold number of the foil leading-out positive foil tab of the positive plate is the same as or different from the fold number of the foil leading-out negative foil tab of the negative plate.

More specifically, a paste coating layer is formed on the foil surface of the positive plate, the ratio of the length of the longest paste coating layer on one surface of the positive plate to the number of the positive foil tabs is 75: 1-1300: 1, and the length unit of the paste coating layer is millimeter.

More specifically, a coating paste layer is formed on the foil surface of the negative plate, the ratio of the length of the longest coating paste layer on one surface of the negative plate to the number of negative foil tabs is 30: 1-200: 1, and the length unit of the coating paste layer is millimeter.

More specifically, the shape of the positive electrode foil tab and/or the negative electrode foil tab is rectangular or trapezoidal.

More specifically, the positive electrode foil tab and/or the negative electrode foil tab are chamfered.

More specifically, the thickness of the foil of the positive plate is 8-16 mu m, and the density of the single-side coating surface of the paste layer of the positive plate is 6.5-15.3 mg/cm²The half-electric rebound thickness of the positive plate is 41-103 mu m.

More specifically, the thickness of the foil of the negative plate is 4-16 mu m, and the single-side coating surface density of the paste layer of the negative plate is 3.8-8.4 mg/cm²The half-electric rebound thickness of the negative plate is 63-177 mu m.

According to the technical scheme provided by the utility model, the utility model discloses break through in the conventional multi-tab lithium battery structure anodal foil utmost point ear and the setting law of negative pole foil utmost point ear, through optimizing the inside just of multi-polar ear lithium ion battery, the quantity of negative pole foil utmost point ear, make anodal lithium speed of taking off and negative pole inlay lithium speed phase-match, optimize the quick charge ability of negative pole, reduce because the condition emergence of the easy lithium of analyzing of negative pole when both speeds mismatch and lead to quick charge to prolong multi-tab battery's long cycle life, promote the cyclicity performance of battery.

Drawings

In order to illustrate the embodiments of the present invention more clearly, the drawings that are needed in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and that other drawings can be obtained by those skilled in the art without inventive effort.

Fig. 1 is a schematic structural view of a multi-tab winding core;

fig. 2 is a schematic structural view of a roll core according to an embodiment of the present invention;

FIG. 3 is a schematic view of an appearance of a roll core according to an embodiment of the present invention;

FIG. 4 is a constant current charge ratio trend chart for example 1 and comparative example 1;

FIG. 5 is a constant current charge ratio trend chart for example 2 and comparative example 2;

fig. 6a and 6b are schematic views of the foil electrode tab chamfering, respectively.

The following describes embodiments of the present invention in further detail with reference to the accompanying drawings.

Detailed Description

The present invention will be described in detail with reference to the accompanying drawings, wherein for convenience of illustration, the drawings showing the structure of the device are not to scale and are partially enlarged, and the drawings are only examples, which should not limit the scope of the invention. It should be noted that the drawings are in simplified form and are not to precise scale, which is only used for the purpose of facilitating and clearly assisting in the description of the embodiments of the present invention.

As shown in fig. 2 and fig. 3 (only a part of tabs are simply shown in fig. 2, and not all layers and all tabs of the winding core are drawn), the lithium ion battery of this embodiment includes a winding core body 1, the winding core body 1 is formed by winding a positive plate 3, a negative plate 2 and a diaphragm 4, the positive foil tab 3a is led out integrally on the foil of the positive plate 3, the negative foil tab 2a is led out integrally on the foil of the negative plate 2, and the positive foil tab 3a and the negative foil tab 2a both extend out of the winding core body 1. The number of the negative electrode foil tabs 2a is different from that of the positive electrode foil tabs 3a, and the number of the negative electrode foil tabs is more than that of the positive electrode foil tabs. More specifically, the utility model discloses a quantity a of negative pole foil utmost point ear and the quantity b of anodal foil utmost point ear satisfy following relation:

wherein n represents the folding number of the negative pole pieces in the roll core body 1, n is a natural number more than 7, a and b are both natural numbers more than 0, a is less than or equal to n, and b is less than or equal to n, namely, the folding number of the negative pole pieces in the roll core body 1 is at least 7, and the roll core body has more than 1 negative pole foil electrode lug and more than 1 positive pole foil electrode lug; one winding of the pole piece forms 2 folds, namely the fold number N is 2N, and N is the number of winding turns (layers) of the pole piece with the paste coating layer on one side or two sides. The number of turns of positive plate corresponds with the number of turns of negative pole piece, and when rolling up the core body and being aluminium foil outsourcing structure, the number of turns of positive plate is the same with the number of turns of negative pole piece, is n, and when rolling up the core body and being unfamiliar outsourcing structure, the number of turns of positive plate is n-2.

Aluminum foil wrapping and diaphragm wrapping are common multi-tab cell structures. The diaphragm outer-packing structure belongs to a multi-tab electric core structure which is commonly used in the early stage, and is characterized in that a positive pole piece is coated in a single or double-sided continuous mode, a negative pole piece coating mode is matched according to the positive pole piece, the outmost layer of the tail end of a winding core is a negative pole or a copper foil which is not embedded with lithium, and the winding core can be additionally wrapped by more diaphragms due to safety consideration, so that the diaphragm outer-packing structure is called as a diaphragm. Because the positive pole piece of diaphragm surrounding structure is two-sided no dislocation coating mode, leads to the book core of coiling according to the Jelly-Roll mode, and the negative pole piece needs additionally to increase 2 and just can match the anodal number of folds, consequently, the book core of diaphragm surrounding structure, the number of folds of positive pole piece is 2 folds less than the number of folds of negative pole piece.

The single two-sided clearance coating that all adopts of positive plate of aluminium foil outsourcing structure, negative pole piece coating mode matches according to the positive plate, and the outmost aluminium foil that is positive pole piece of roll core ending need not additionally to increase the diaphragm and guarantees the security. Because the positive pole piece of the aluminum foil outer packaging structure is coated in a double-sided staggered manner, the positive pole can be matched with the negative pole piece without extra folding number, and therefore, the folding number of the positive pole piece and the folding number of the negative pole piece are the same in the winding core of the aluminum foil outer packaging structure.

Active materials are coated on the surfaces of the positive plate foil and the negative plate foil in the winding core, so that a paste coating layer is formed on the plate foil, the lengths of the paste coating layers on the two side surfaces of the plate foil may be different, and the ratio of the length l (unit mm) of the longest paste coating layer on the single surface of the negative plate to the number of tabs of the negative plate foil is 30: 1-200: 1; the ratio of the length k (unit mm) of the longest coating layer on one surface of the positive plate to the number of positive foil tabs is 75: 1-1300: 1.

The number of folds of the positive foil leading-out positive foil tab of the positive plate and the number of folds of the foil leading-out negative foil tab of the negative plate can be the same or different, for example, a winding core with an aluminum foil outer-wrapping structure is taken as an example, the positive plate and the negative plate are respectively provided with 15 folds, the negative plate leads out the negative foil tab in the 1 st, 3 rd, 5 th, 7 th, 9 th, 11 th, 13 th, 15 th folds, 8 positive foil tabs can be led out totally, the positive plate can lead out the positive foil tab in the 2 nd, 7 th, 14 th folds, 3 positive foil tabs can be led out totally, or the positive plate can lead out the positive foil tab in the 3 rd, 7 th, 11 th folds, namely, the positive and negative plates can respectively lead out the positive and negative foil tabs in the same fold, or lead out the positive and negative foil tabs in different folds respectively.

The foil of the positive and negative electrode plates can be formed into a foil tab by means of die cutting, such as laser die cutting or die cutting, the shape of the foil tab can be rectangular or trapezoidal, preferably, the intersection of adjacent sides of the foil tab can be chamfered, and as shown in fig. 6a and fig. 6b, the rectangular foil tab with a chamfer and the trapezoidal foil tab with a chamfer are respectively shown in schematic diagrams. More specifically, the thickness of the positive plate foil is 8-16 mu m, and the single-side coating surface density of the paste layer of the positive plate is 6.5-15.3 mg/cm²The half-electric rebound thickness of the positive plate is 41-103 mu m (including the thickness of a current collector); the thickness of the negative plate foil is 4-16 mu m, and the single-side coating surface density of the coating layer of the negative plate is 3.8-8.4 mg/cm²The half-electric rebound thickness of the negative plate is 63-177 mu m (including the thickness of the current collector). The positive and negative plates may be single-layer, double-layer, or triple-layer coated. The active material of the positive plate can be one or more of lithium cobaltate, NCM ternary, NCA ternary and lithium iron phosphate, and the active material of the negative plate can be one or more of artificial graphite, natural graphite, silica negative electrode and silicon carbon negative electrode.

Example 1

This embodiment is 5C of diaphragm outsourcing structure fills battery soon, rolls up the core body and has 25 negative pole pieces and 23 positive plate that roll over, and the negative pole piece is in 1 st, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, 25 and rolls over out negative pole foil utmost point ear, draws 13 negative pole foil utmost point ears altogether, and the positive plate is rolled over out positive foil utmost point ear at the odd number, draws 4 positive foil utmost point ears altogether at 3, 9, 15, 21 book.

Comparative example 1

Comparative example 1 is also a 5C quick-charging battery with a diaphragm wrapping structure, the winding core body is provided with a 25-fold negative electrode plate and a 23-fold positive electrode plate, the negative electrode plates are folded into negative foil tabs at the 1 st, 3 rd, 5 th, 7 th, 9 th, 11 th, 13 th, 15 th, 17 th, 19 th, 21 th, 23 th and 25 th positions, 13 negative foil tabs are led out altogether, the positive electrode plates are folded into positive foil tabs at the 1 st, 3 th, 5 th, 7 th, 9 th, 11 th, 13 th, 15 th, 17 th, 19 th, 21 th and 23 th positions, and 12 positive foil tabs are led out altogether.

The number of negative electrode foil tabs of comparative example 1 and example 1 was the same, but the number of positive electrode foil tabs of example 1 was reduced to 4. The cells of comparative example 1 and example 1 were subjected to a 5C charging test, and fig. 4 is a trend graph of constant current charging ratio for the first 20 cycles, and as can be seen from the two linear trend lines of fig. 4, the constant current charging ratio for the first 20 cycles of example 1 was significantly improved as compared to comparative example 1.

Example 2

The embodiment is the 6C of aluminium foil outsourcing structure and fills the battery soon, rolls up the core body and has 25 positive plates and 25 negative plates of rolling over, and the quantity of the negative pole foil utmost point ear of drawing forth on the negative plate is 25, and every book of negative plate all goes out 1 negative pole foil utmost point ear promptly, and the quantity of the anodal foil utmost point ear of drawing forth on the positive plate is 6, respectively rolls over anodal foil utmost point ear at 3 rd, 7 th, 11, 15, 19, 23.

Comparative example 2

Comparative example 2 is also the 6C quick-charging battery of aluminium foil outsourcing structure, rolls up the core body and has 25 positive plates and 25 negative plates of book, and the place that differs with example 2 lies in: the number of foil tabs led out from the positive electrode sheet and the negative electrode sheet is 25, namely 1 foil tab is led out from each folding of the positive electrode sheet and the negative electrode sheet.

The cells of comparative example 2 and example 2 were subjected to 6C charging test, fig. 5 is a trend graph of constant current charging ratio for the first 20 cycles, and as can be seen from the two linear trend lines of fig. 5, the constant current charging ratio for the first 20 cycles of example 2 was significantly improved as compared to comparative example 2.

The above embodiments are only used to illustrate the technical solutions of the present invention and not to limit the same, although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the present invention can still be modified or replaced with equivalents, and any modification or equivalent replacement without departing from the spirit and scope of the present invention should be covered by the scope of the present invention.

Claims

1. The utility model provides a lithium ion battery, includes the book core body of coiling formation by positive plate, negative pole piece and diaphragm, positive foil electrode lug has been drawn forth on the foil of positive plate, negative foil electrode lug has been drawn forth on the foil of negative plate, its characterized in that:

the quantity of negative pole foil utmost point ear is greater than the quantity of anodal foil utmost point ear, just the quantity a of negative pole foil utmost point ear with the relation between the quantity b of anodal foil utmost point ear is:

2. The lithium ion battery of claim 1, wherein: roll up the number of turns of negative pole piece in the core body and be more than 7 book, roll up the core body and have more than 1 negative pole foil tab and more than 1 positive pole foil tab.

3. The lithium ion battery of claim 1, wherein: the winding core body is of an aluminum foil outer-wrapping structure, and the folding number of the positive plate is the same as that of the negative plate; or the winding core body is of a diaphragm wrapping structure, and the number of folds of the positive plate is 2 folds less than that of the negative plate.

4. The lithium ion battery of claim 1, wherein: the folding number of the foil leading-out positive foil electrode lug of the positive plate is the same as or different from that of the foil leading-out negative foil electrode lug of the negative plate.

5. The lithium ion battery of claim 1, wherein: the positive plate is characterized in that a paste coating layer is formed on the foil surface of the positive plate, the ratio of the length of the longest paste coating layer on one surface of the positive plate to the number of the positive foil tabs is 75: 1-1300: 1, and the length unit of the paste coating layer is millimeter.

6. The lithium ion battery of claim 1, wherein: the foil surface of the negative plate is provided with a paste coating layer, the ratio of the length of the longest paste coating layer on one surface of the negative plate to the number of the negative foil tabs is 30: 1-200: 1, and the length unit of the paste coating layer is millimeter.

7. The lithium ion battery of claim 1, wherein: the shape of the positive electrode foil tab and/or the negative electrode foil tab is rectangular or trapezoidal.

8. The lithium ion battery of claim 1, wherein: and the positive foil electrode lug and/or the negative foil electrode lug are chamfered.

9. The lithium ion battery of claim 1, wherein: the thickness of the foil of the positive plate is 8-16 mu m, and the density of the single-side coating surface of the paste coating layer of the positive plate is 6.5-15.3 mg/cm²The half-electric rebound thickness of the positive plate is 41-103 mu m.

10. The lithium ion battery of claim 1, wherein: the thickness of the foil of the negative plate is 4-16 mu m, and the single-side coating surface density of the paste layer of the negative plate is 3.8-8.4 mg/cm²The half-electric rebound thickness of the negative plate is 63-177 mu m.