CN212571082U

CN212571082U - Battery cell

Info

Publication number: CN212571082U
Application number: CN202021700356.3U
Authority: CN
Inventors: 余开明; 靳玲玲
Original assignee: Zhuhai Cosmx Power Battery Co Ltd
Current assignee: Zhuhai Cosmx Power Battery Co Ltd
Priority date: 2020-08-15
Filing date: 2020-08-15
Publication date: 2021-02-19
Anticipated expiration: 2030-08-15

Abstract

An electric core belongs to the technical field of improving the performance of a power battery. The utility model aims at solving among the prior art battery middle part heat concentration, whole temperature distribution inhomogeneous, the battery cycle life who leads to for a long time overheated reduces and the too high and safety problem of multiplying power charge-discharge temperature rise, specifically, electric core includes first pole piece, diaphragm, second pole piece, first pole piece with be provided with between the second pole piece the diaphragm, be provided with the through-hole on one of them at least one of first pole piece and second pole piece, the through-hole of adjacent pole piece overlaps or staggers. The utility model discloses satisfied large capacity lithium ion power battery performance from pole piece structural design and improved, be favorable to lithium ion battery's heat dissipation very much, solve the uneven and overheated negative effects of battery middle zone's temperature distribution. The test result shows that in the continuous charging and discharging process, the temperature of the electric core main body is obviously reduced, the liquid retention amount is increased, and the cycle life of the battery is prolonged.

Description

Battery cell

Technical Field

The utility model belongs to the technical field of battery performance optimization, concretely relates to electricity core.

Background

The development direction of the automobile in the future is the trend of intellectualization and electromotion, and the European union and the country clearly propose and cancel a fuel plan of a passenger car. In the future 2030, a power battery for supplying energy to automobile driving will be in rapid development and have a wide market prospect. As is well known, the energy ratio of the power battery is higher, the monomer capacity is generally more than or equal to 30Ah, and the capacity of the mainstream soft package power battery in the current market reaches 50Ah/60 Ah; the square power batteries reach more than 100 Ah; resulting in a total number of layers of cell plates and separators of typically over 100 layers. As the capacity of a power battery is increased more and more, when the motor is driven under the condition of the same multiplying power, the overcurrent of the battery is larger, and the generated heat Q is equal to I²The more Rt. The maximum use temperature of the lithium ion single battery is about 70 ℃, and the decomposition and gas generation of electrolyte in the battery can be caused when the battery is used under an overheating condition, so that the phenomena of increased side reactions, SEI film damage and the like are caused, and the performances of the battery in all aspects are reduced. Many thermal simulation studies show that the temperature gradient and the thermal stress inside the battery core are increased and the middle part is in a heat concentration area in the use process of the battery. The reasons are the following two points: firstly, the higher the battery capacity is, the more the number of layers is, the untimely heat dissipation of the middle part during charging and discharging leads to heat accumulation; secondly, the electrolyte in the middle area is not fully infiltrated, and the phenomena of vicious circle, black spots and the like caused by the slow consumption of the electrolyte by the self thermal diffusion result in the large resistance of the middle area. Due to the above reasons, the middle part of the battery is in an overheated state for a long time, the current density is too high due to overheating, and the current in the middle area is larger than the set value during charging and discharging, so that phenomena such as lithium precipitation and the like are generated, and the safety performance is further influenced. How to solve the problem of uneven integral temperature distribution in the use process of the battery and reduce the generation of heat effect, and the improvement of the cycle life and the safety performance of the power battery becomes an urgent task for the research of the lithium battery industry.

SUMMERY OF THE UTILITY MODEL

The utility model aims at providing an electricity core in order to solve among the prior art battery mid portion heat concentrate, whole temperature distribution inhomogeneous, the battery cycle life who leads to for a long time overheated reduces and the too high and safety problem of multiplying power charge-discharge temperature rise.

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

the battery cell comprises a first pole piece, a diaphragm and a second pole piece, wherein the diaphragm is arranged between the first pole piece and the second pole piece, and at least one of the first pole piece and the second pole piece is provided with a through hole.

The utility model discloses beneficial effect for prior art does: the pole piece structure design satisfies the performance improvement of the high-capacity lithium ion power battery, is very favorable for the heat dissipation of the lithium ion battery, and solves the problems of uneven temperature distribution and overheating negative effects in the middle area of the battery. The test result shows that in the continuous charging and discharging process, the temperature of the electric core main body is obviously reduced, the liquid retention amount is increased, and the cycle life of the battery is prolonged.

Drawings

FIG. 1 is a schematic view of punching holes on a pole piece in example 1;

FIG. 2 is a schematic view of punching holes in the pole piece according to example 4;

FIG. 3 is a schematic view of punching holes in the pole piece according to example 5;

FIG. 4 is a schematic view of punching holes in the electrode sheet according to example 6;

wherein, 1-pole piece, 2-through hole, 3-pole ear and 4-central line.

Detailed Description

The technical solution of the present invention is further described below with reference to the accompanying drawings and examples, but not limited thereto, and all modifications or equivalent substitutions may be made to the technical solution of the present invention without departing from the spirit of the technical solution of the present invention, and all the modifications and substitutions are intended to be covered by the scope of the present invention.

The principle of the utility model is that: after the power battery pole piece die cutting process, punching a hole in the middle area of the pole piece, and then preparing a battery cell according to a normal flow. The heat dissipation of the middle area of the lithium ion battery is facilitated, and the problems of uneven temperature distribution and overheating negative effects of the middle area of the battery are solved.

The first embodiment is as follows: the battery cell comprises a first pole piece, a diaphragm and a second pole piece, wherein the diaphragm is arranged between the first pole piece and the second pole piece, and at least one of the first pole piece and the second pole piece is provided with a through hole. This novel electric core structure is applicable to following chemical system: any one or more of a lithium cobaltate system, a lithium manganate system, a lithium iron phosphate system, a ternary system, a lithium-rich manganese-based system, a lithium titanate system, a lithium sulfur system and a solid electrolyte system. And (3) deducting the capacity loss caused by the punching area when the capacity is designed, and testing the liquid retention capacity, the temperature rise, the circulation and the like of the battery after the battery is made into a finished product according to a normal process.

The second embodiment is as follows: in an electrical core according to a first specific embodiment, through holes of adjacent pole pieces are overlapped or staggered.

The third concrete implementation mode: in the battery cell according to the first embodiment, the first pole piece and the second pole piece on the outermost layer are not provided with through holes.

The fourth concrete implementation mode: in a first specific embodiment, the battery cell is a laminated battery cell, and a through hole is formed in a middle area of each layer of the pole piece of the battery cell.

The fifth concrete implementation mode: in the battery cell of the fourth specific embodiment, the through holes are arranged in a single row and located on the center line of the pole piece in the width direction, the through holes are uniformly distributed on the pole piece according to the punching quantity of each pole piece, and the distance T1 between each hole and each hole in the width direction is 2-21 mm. The unwound horizontally disposed pole pieces are generally described in terms of width, length, and thickness directions, with dimensions of the sides being: length > width > height.

The sixth specific implementation mode: in the battery cell, the through holes are arranged in double rows and are symmetrically arranged on two sides of a center line of a folding position of the pole piece in the width direction, the distance L1 between the double holes in the length direction is 2-21 mm, and the distance T1 between the holes in the width direction is 2-21 mm according to the uniform distribution of the number of each pole piece.

The seventh embodiment: in a specific embodiment, the battery cell is a winding battery cell, and a through hole is formed in a middle area of each folded pole piece of the battery cell.

The specific implementation mode is eight: in the battery cell according to the seventh embodiment, the through holes are arranged as a single row of holes, and are located on a center line of the pole piece folded in the length direction, and an interval L2 between the holes in the length direction is equal to a width of each pole piece folded in the length direction.

The specific implementation method nine: in the battery cell of the seventh embodiment, the through holes are arranged in two rows of holes, the two sides of the center line of the folded position of the pole piece in the length direction are symmetrical, and the interval L2 between the holes in the length direction is equal to the interval T2 between each folded width and each hole in the width direction of the pole piece, which is 2-21 mm.

The fourth to ninth embodiments specifically describe the through hole structures in the laminated cell and the winding cell, which can be said to provide various implementation modes for battery heat dissipation.

The detailed implementation mode is ten: in an electrical core according to a first embodiment, the specification of the through hole is as follows: the diameter of each single hole is 1-20 mm, the number of the single holes is more than or equal to 2, and the single holes are flexibly distributed on the cathode plate according to design requirements. And calculating the sacrificial pole piece area to total cathode piece area according to the total number of the through holes and the area of the holes, and deducting the capacity loss caused by the through holes.

Example 1:

taking a 60Ah battery with a power laminated structure of a ternary NCM chemical system as an example, the battery process manufacturing flow comprises the following key steps: the preparation of the slurry (cathode and anode) → coating (cathode and anode) → pole piece rolling (cathode and anode) → pole piece hardware die cutting (cathode and anode) → cathode piece punching preparation → lamination preparation bare cell (containing diaphragm) → welding → encapsulation → injection liquid → formation → air extraction → sorting → detection. In the punching preparation process of the cathode plate, through holes with the diameter of 5mm are punched on the plate with the width of 100 mm to 200mm, the number of the through holes is 3, the through holes are positioned on the central line in the width direction, and the through holes are distributed at the vertical interval of 10mm, and each row is provided with 1 through hole, as shown in fig. 1.

Example 2:

this example is different from example 1 in that in the cathode sheet punching preparation process, through holes with a diameter of 10mm were punched in the cathode sheet, the number of the through holes was 3, the through holes were located on the center line in the width direction, and the vertical intervals T1 were distributed at 13mm intervals, 1 per row.

Example 3:

the difference between this example and example 1 is that in the punching preparation process of the cathode sheet, through holes with a diameter of 15mm are punched on the cathode sheet, the number of the through holes is 3, the through holes are positioned on the central line in the width direction, and the through holes are distributed at a vertical interval T1 of 17mm, and each row is 1.

Example 4:

the difference between this example and example 1 is that in the punching preparation process of the cathode sheet, through holes with a diameter of 5mm are punched on the cathode sheet, the number of the through holes is 6, the through holes are located on both sides of the center line in the width direction, the vertical interval T1 is 10mm, the symmetrical interval L1 is 10mm, the through holes are distributed in three rows, 2 in each row, and fig. 2 shows.

Example 5:

taking a 20Ah power battery with a power multi-tab winding structure of a ternary NCM chemical system as an example, the battery process manufacturing flow comprises the following key steps: the preparation of the slurry (cathode and anode) → coating (cathode and anode) → pole piece rolling (cathode and anode) → pole piece laser die cutting (cathode and anode) → cathode piece punching preparation → multi-tab winding preparation of bare cell (containing diaphragm) → welding → packaging → liquid injection → formation → air extraction → sorting → detection. In the punching preparation process of the cathode plate, the size width and the length of the cathode plate are 100 and 5000mm, the total number is 20 folds, the width is 250mm in each fold, through holes with the diameter of 10mm are punched on the cathode plate, the through holes are positioned on the central line of the length direction of the cathode plate, and the interval L2 is 250 mm; the number of the through holes is 1 per turn, and the through holes are distributed in a row as shown in figure 3.

Example 6:

the difference between the embodiment and the embodiment 5 is that in the punching preparation process of the cathode plate, through holes with the diameter of 5mm are punched on the cathode plate, the through holes are positioned on two symmetrical sides of the central line of the length direction of the electrode plate, and the interval L2 in the parallel direction is 250 mm; the holes are spaced 10mm apart in the vertical direction T2. The number of the through holes is 2 per turn, and the through holes are distributed in two rows as shown in figure 4.

Example 7:

the difference between this example and example 1 is that in the cathode sheet punching preparation process, the cathode sheet is punched with through holes having a diameter of 1mm, the number of the through holes is 3, the through holes are located on the center line in the width direction, and the through holes are distributed at a vertical interval T1 of 3mm, 1 in each row.

Example 8:

the difference between this example and example 1 is that in the punching preparation process of the cathode sheet, through holes with a diameter of 1mm are punched on the cathode sheet, the number of the through holes is 6, the through holes are located on both sides of the center line in the width direction, the vertical interval T1 is 3mm, the symmetrical interval L1 is 3mm, the through holes are distributed in three rows, 2 in each row, and fig. 2 shows.

Comparative example 1:

this comparative example is the same as example 1 except that the punching step of the cathode sheet was not performed, unlike example 1.

Comparative example 2:

this comparative example is the same as example 5 except that the punching step of the cathode sheet was not performed, unlike example 5.

The finished batteries prepared in examples 1-6 and comparative examples 1-2 were made into batteries with the same capacity and subjected to liquid retention amount statistics, 3C rate discharge middle region temperature rise test, and 1C/1C cycle life test, and the statistical results are as follows.

TABLE 1 statistical table of test results of examples and comparative examples

The results show that the liquid retention amount of the embodiment is increased in different degrees compared with that of the comparative example, the temperature rise of the concerned 3C discharge middle area is obviously reduced by about 15 ℃, and the effect is very obvious; the 500 week cycle life of the various examples is also superior to the comparative examples.

Claims

1. The utility model provides an electric core, includes first pole piece, diaphragm, second pole piece, first pole piece with be provided with between the second pole piece the diaphragm, its characterized in that: at least one of the first pole piece and the second pole piece is provided with a through hole.

2. The cell of claim 1, wherein: the through holes of adjacent pole pieces are overlapped or staggered.

3. The cell of claim 1, wherein: the first pole piece and the second pole piece on the outermost layer are not provided with through holes.

4. The cell of claim 1, wherein: the battery cell is a laminated battery cell, and a through hole is formed in the middle area of each layer of pole piece of the battery cell.

5. The cell of claim 4, wherein: the through holes are arranged in a single row of holes and located on the center line of the pole piece in the width direction, the punching quantity of each pole piece is uniformly distributed on the pole piece, and the interval T1 between the holes in the width direction is 2-21 mm.

6. The cell of claim 4, wherein: the through-hole sets up to the double row hole, is located pole piece width direction fifty percent discount position central line bilateral symmetry position, and length direction diplopore interval L1 is 2 ~ 21mm, according to every quantity evenly distributed, and interval T1 is 2 ~ 21mm between width direction hole and the hole.

7. The cell of claim 1, wherein: the battery cell is a winding battery cell, and a through hole is formed in the middle area of each folded pole piece of the battery cell.

8. The cell of claim 7, wherein: the through holes are arranged in a single row and are positioned on the folding central line of the length direction of the pole piece, and the interval L2 between the holes in the length direction is equal to the width of each folding pole piece.

9. The cell of claim 7, wherein: the through-hole sets up to the double row hole, is located pole piece length direction fifty percent discount position central line bilateral symmetry, and interval L2 between length direction hole and the hole equals that the pole piece is every to be rolled over width, width direction hole and interval T2 between the hole is 2 ~ 21 mm.

10. The cell of claim 1, wherein: the specification of the through hole is as follows: the diameter of each single hole is 1-20 mm, and the number of the single holes is more than or equal to 2.