CN115275531B

CN115275531B - Preparation method of multi-tab battery cell and multi-tab battery cell

Info

Publication number: CN115275531B
Application number: CN202211171617.0A
Authority: CN
Inventors: 张国帅; 朱金保; 于哲勋
Original assignee: Jiangsu Zenio New Energy Battery Technologies Co Ltd
Current assignee: Jiangsu Zenio New Energy Battery Technologies Co Ltd
Priority date: 2022-09-26
Filing date: 2022-09-26
Publication date: 2022-12-09
Anticipated expiration: 2042-09-26
Also published as: CN115275531A

Abstract

The invention relates to a preparation method of a multi-tab battery cell and the multi-tab battery cell, wherein the preparation method comprises the following steps: s1, winding a first pole piece, a diaphragm and a second pole piece to form a full-lug battery cell; s2, die-cutting the whole lug area of the full lug battery cell to form a multi-lug rudiment with a first pole piece lug, a second pole piece lug and a diaphragm false lug overlapped; and S3, performing regional and selective removal treatment on the overlapped multi-pole-lug prototypes to obtain a first pole lug formed by only overlapping the first pole lug and a second pole lug formed by only overlapping the second pole lug. The invention changes the process steps of the prior art, adopts the manufacturing idea of integrating and then locally from top to bottom, obtains an integral structure in advance through a one-step forming method, and then obtains a finished product through local repair, thereby improving the integral processing efficiency and quality.

Description

Preparation method of multi-tab battery cell and multi-tab battery cell

Technical Field

The invention relates to the technical field of battery cell preparation, in particular to a preparation method of a multi-tab battery cell and the multi-tab battery cell.

Background

In recent years, industries related to new energy resources develop rapidly, the lithium ion battery technology is popularized and applied in a burst mode in the subdivided fields of electric automobiles, base station energy storage, electric tools and the like, and the requirements of the market on the performance and the capacity of the lithium ion battery technology are further increased. In order to improve power performance, the full-tab technology is adopted in more and more batteries at present, and on the basis, the full-tab technology is gradually developed into the multi-tab technology in order to further improve energy density.

For example, patent nos.: chinese patents CN113851604A, CN111668444A, CN114300751A, etc. all disclose a method for preparing a multi-tab electrical core, which, with reference to fig. 1 and fig. 2, combines the above-mentioned patents to summarize a conventional core forming method adopted by the existing multi-tab technology, and specifically includes the following main steps:

step 1, cutting a first pole piece 10 and a second pole piece 20 which are taken as components in advance through a die cutting process to form a first pole piece tab 102, a first pole piece main body 101, a second pole piece tab 202 and a second pole piece main body 201; because the tabs on the first pole piece 10 and the second pole piece 20 need to be overlapped subsequently, the size of the tab spacing is controlled accurately when the respective die cutting is carried out, so that no matter a mechanical cutter or laser cutting is adopted, the tab spacing can be controlled accurately, the equipment investment and maintenance cost is high, and meanwhile, due to the high cutting frequency, the damage to the active main material area of the tabs cannot be avoided in the process, and the material waste and the quality risk are caused.

Step 2, after the die cutting pretreatment is finished, winding and forming the first pole piece 10 and the second pole piece 20; because the tab part of the die-cut pole piece is in a discontinuous state, as shown in a position a in fig. 2, the tab is easy to warp upwards, downwards or warp in the tape moving process, and even the root of the tab is torn when passing through a rotating roller, so that the material waste is caused, and the integral winding forming efficiency is also seriously tired; in addition, because the pole piece incoming material has coating weight/thickness fluctuation, tension fluctuation and other inherent problems exist in the winding process, such as the position b in fig. 2, the winding core pole ear after winding forming is easy to form a dislocation phenomenon, and subsequent assembly processing and battery performance are influenced.

In summary, the conventional bottom-up assembly concept (local assembly and integral assembly) in the manufacturing industry is adopted in the preparation method of the multi-tab battery cell in the prior art, and the method is mature and reliable, and has the defects that each component needs to be preprocessed in advance, so that on one hand, the workload is greatly increased, and on the other hand, high requirements are placed on the single size design, the processing precision and the integral matching precision of each component.

Disclosure of Invention

Therefore, the technical problem to be solved by the invention is to overcome the defects of the prior art for preparing the multi-tab battery cell, and the method for preparing the multi-tab battery cell and the multi-tab battery cell prepared by the method are provided.

In order to solve the technical problem, the invention provides a preparation method of a multi-tab battery cell, which comprises the following steps:

s1, winding a first pole piece, a diaphragm and a second pole piece to form a full-lug battery cell;

s2, performing die cutting treatment on the whole lug area of the full lug battery cell to form a multi-lug rudiment with a first pole piece lug, a second pole piece lug and a diaphragm false lug overlapped;

and S3, removing the overlapped multi-pole lug rudiment regionally and selectively to obtain a first pole lug formed by only overlapping the first pole lug and a second pole lug formed by only overlapping the second pole lug.

In one embodiment of the present invention, in step S1, the first and second pole pieces are arranged to partially protrude from the separator in the tab area.

In one embodiment of the present invention, in step S2, after the die cutting process, the multi-tab prototype includes a first tab part, a second tab part and an edge overlapping part, wherein:

the first pole ear part and the second pole ear part respectively comprise a plurality of layers of first pole piece tabs, diaphragms and second pole piece tabs which are alternately and partially overlapped;

the edge overlapping part comprises a plurality of layers of first pole piece tabs, a diaphragm and second pole piece tabs which are alternately and completely overlapped.

In an embodiment of the present invention, in step S3, the following steps are specifically included:

s3-1-1, soaking the first pole lug part and all the edge overlapped parts in a first chemical liquid, corroding off a second pole lug in the first pole lug part and the edge overlapped parts, reserving the first pole lug and a diaphragm, forming a first pole lug reserving the first pole lug and the diaphragm in the first pole lug part, and forming a first pole lug cladding redundancy in the edge overlapped parts, namely enabling the edge overlapped parts of the first pole lug to protrude out of the connection position of the first pole lug and the first pole piece;

and S3-1-2, soaking the second pole lug part and part of the edge overlapping part in a second chemical solution, corroding off a first pole piece tab in the second pole lug part and the edge overlapping part, reserving the second pole piece tab and a diaphragm, forming a second pole piece tab reserving the second pole piece tab and the diaphragm on the second pole lug part, and forming second pole piece tab coating redundancy on the edge overlapping part, namely enabling the edge overlapping part of the second pole piece to protrude out of the connecting position of the second pole piece and the second pole piece.

In an embodiment of the invention, the method further includes step S3-1-3, after the first tab and the second tab are obtained, performing edge cleaning on the first tab and the second tab, and removing the residual first chemical liquid and second chemical liquid.

In one embodiment of the invention, in step S3-1-3, a third chemical solution is used for edge cleaning, and the membranes at the first tab and the second tab are removed by etching while cleaning.

In an embodiment of the present invention, before step S1, the first pole piece and the second pole piece are subjected to a pre-damage treatment, and a first tab pre-damage and a second tab pre-damage larger than a target tab width are formed on the first pole piece and the second pole piece, respectively.

and S3-2-1, removing the pre-damage of the first pole lug and the pre-damage fracture of the second pole lug to form a first pole lug reserving the first pole lug and a second pole lug reserving the second pole lug.

In one embodiment of the invention, the method of pre-wound treatment comprises localized linear micro-hole cutting or linear chemical etching.

In order to solve the technical problem, the invention also provides a multi-tab battery cell which is prepared by the method,

compared with the prior art, the technical scheme of the invention has the following advantages:

the invention discloses a preparation method of a multi-pole lug battery cell, which is based on the preparation idea, changes the preparation steps of the prior art, adopts the manufacturing idea of integrating and then locally from top to bottom, and first winds a first pole piece, a diaphragm and a second pole piece used for preparing the battery cell to form the full-pole lug battery cell, obtains an integral structure in advance through a one-step forming method, then carries out local repair, carries out die cutting treatment on the whole pole lug area of the full-pole lug battery cell to obtain a multi-pole lug rudiment, the multi-pole lug rudiment is formed by overlapping the first pole piece pole lug, the second pole piece pole lug and a diaphragm false pole lug at the moment, only forms a battery cell structure in shape but cannot carry out safe charging and discharging, and finally carries out regional and selective removal treatment on the multi-pole lug rudiment, selectively removes the first pole piece pole lug and the second pole piece lug in different regions, thereby respectively forming a first pole lug formed by overlapping the first pole piece pole lug and a second pole piece lug formed by overlapping only;

according to the preparation method of the multi-tab battery cell, the first pole piece, the diaphragm and the second pole piece are wound and molded, then the whole die cutting is carried out, the whole-tab idea is used for replacing the traditional tab-whole route, namely, the post-processing of the roll core level is used for replacing the die cutting of the traditional method at the pole piece level, the problems of the traditional multi-tab winding are avoided, and the preparation method has obvious advantages in the aspects of production efficiency, product yield and the like; and moreover, material waste caused by the connection and disconnection of the pole pieces and the poor size of the pole lugs is reduced, the cost of related equipment is reduced, potential mechanical damage possibly caused to the pole pieces by a die cutting process is avoided, and the performance of the battery is improved.

Drawings

In order that the present disclosure may be more readily understood, a more particular description of the disclosure will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings

Fig. 1 is a flow chart of steps of a method of manufacturing a multi-tab cell of the prior art;

fig. 2 is a process flow diagram of a prior art method of making a multi-tab cell;

fig. 3 is a flow chart of steps of a method of manufacturing a multi-tab cell of the present invention;

fig. 4 is a process flow diagram of a method of making a multi-tab cell of the present invention;

fig. 5 is a schematic structural diagram of a top projection of a full tab cell in step S1 in embodiment 1 of the present invention;

FIG. 6 is a process flow chart of step S2 in example 1 of the present invention;

FIG. 7 is a process flow chart of step S3 in example 1 of the present invention;

FIG. 8 is a process flow diagram of a pre-wound treatment according to example 2 of the present invention;

FIG. 9 is a process flow chart of step S3 in example 2 of the present invention.

The specification reference numbers indicate: 10. a first pole piece; 101. a first pole piece main body; 102. a first pole tab; 102S, pre-damaging a first tab; 20. a second pole piece; 201. a second diode body; 202. a second pole tab; 202S, pre-damaging a second tab; 30A, a full-tab battery cell; 30B, semi-finished multi-tab battery cells; 30C, finished multi-tab battery cores; 301. a body region; 302. a polar ear region; 3021. a first pole piece tab; 3021A, a first pole ear; 3022. a second pole piece tab; 3022A, second pole ear; 3023. a diaphragm false tab; 303. an edge overlapping portion; s01, first chemical liquid; s02, second chemical liquid; s03 and third chemical liquid.

Detailed Description

The present invention is further described below in conjunction with the following figures and specific examples so that those skilled in the art may better understand the present invention and practice it, but the examples are not intended to limit the present invention.

As described above, the multi-tab battery cell is formed by winding the first pole piece 10, the second pole piece 20 and the diaphragm which are arranged in a stacked manner, in the prior art, when the multi-tab battery cell is prepared, the first pole piece 10 and the second pole piece 20 are cut by adopting a die cutting process to form a plurality of first pole tab pieces 102 and second pole tab pieces 202, then the first pole piece 10, the second pole piece 20 and the diaphragm are wound, after winding, different first pole tab pieces 102 are mutually overlapped to form a first tab, different second pole tab pieces 202 are mutually overlapped to form a second tab, and the first tab and the second pole tab are arranged at intervals; in order to overlap the first pole lug piece 102 and the second pole lug piece 202 at different positions after winding and to form a first pole lug and a second pole lug which can be arranged at intervals, it is conceivable that the positions of each pole lug piece after die cutting need to be accurately calculated according to the curvature radius of winding before cutting, and the pole lug pieces after winding can be overlapped only by the method.

The invention analyzes the difficulty existing in the preparation of the multi-tab battery cell by adopting the existing preparation method, changes the preparation steps of the prior art from the preparation idea, adopts the manufacturing idea of whole and part from top to bottom, and discloses a preparation method of the multi-tab battery cell, which comprises the following steps as shown in reference to fig. 3 and fig. 4:

step S1, winding a first pole piece 10, a diaphragm, and a second pole piece 20 by using a conventional winding technology to form a full tab battery cell 30A, where the full tab battery cell 30A includes a main body region 301 and a tab region 302, and because a first pole tab 102 and a second pole tab 202 are not formed by cutting the first pole piece 10 and the second pole piece 20, it is not necessary to consider whether the positions of the pole tabs overlap or not during winding, and it is also not necessary to consider whether the first pole piece 10 and the second pole piece 20 slide at opposite positions during winding, and at the same time, there is no requirement for the coating thickness and weight of the first pole piece 10 and the second pole piece 20;

in the embodiment, a lamination technology may also be adopted, and the first pole piece 10, the diaphragm, and the second pole piece 20 are stacked to form a full tab battery cell 30A;

step S2, die cutting is carried out on the whole pole ear area 302 of the full pole ear electric core 30A, and a semi-finished product multi-pole ear electric core 30B with a multi-pole ear rudiment is obtained, wherein the multi-pole ear rudiment comprises a first pole piece pole ear 3021, a second pole piece pole ear 3022 and a diaphragm false pole ear 3023 which are arranged in an overlapped mode, and the multi-pole ear rudiment after integral die cutting processing is adopted and has a certain overlapped pole ear structure, but the multi-pole ear rudiment obtained at the moment is formed by overlapping the first pole piece pole ear 3021, the second pole piece pole ear 3022 and the diaphragm false pole ear 3023, only an electric core structure is formed in shape, and safe charging and discharging cannot be carried out;

and S3, performing regional and selective removal treatment on the overlapped multi-tab prototype to obtain a first tab formed by only overlapping the first pole tab 3021 and a second tab formed by only overlapping the second pole tab 3022, so as to obtain a finished multi-tab battery cell 30C, wherein the multi-tab prototype obtained in the step S2 is formed by overlapping the first pole tab 3021, the second pole tab 3022 and the membrane dummy tab 3023, when the first tab is required to be obtained, the second pole tab 3022 and the membrane dummy tab 3023 in the multi-tab prototype structure can be removed, and when the second tab is required to be obtained, the first pole tab 3021 and the membrane dummy tab 3023 in the multi-tab prototype structure can be removed.

According to the preparation method of the multi-tab battery cell, the first pole piece 10, the diaphragm and the second pole piece 20 are wound and formed, then the integral die cutting is carried out, the idea of firstly preparing the integral winding structure and then preparing the tabs is used for replacing the traditional method of firstly preparing the tabs, the post-processing of a winding core level is adopted for replacing the traditional method of die cutting at the pole piece level in the integral winding route, the problems of the traditional multi-tab winding are avoided, and the preparation method has remarkable advantages in the aspects of production efficiency, product yield and the like; and moreover, material waste caused by the connection and disconnection of the pole pieces and the poor size of the pole lugs is reduced, the cost of related equipment is reduced, potential mechanical damage possibly caused to the pole pieces by a die cutting process is avoided, and the performance of the battery is improved.

According to the preparation method of the multi-pole-ear battery cell, the winding process and the die cutting process are respectively adopted in the step S1 and the step S2, the difference from the traditional process is not large, the key point and difficulty of the preparation method are that in the step S3, namely how to remove part of structures in the first pole piece lug 3021, the second pole piece lug 3022 and the diaphragm false pole lug 3023 which are arranged in a stacked mode after winding, and only a needed structure is reserved; since the thicknesses of the first pole piece 10, the second pole piece 20 and the diaphragm are all relatively thin, layered cutting cannot be achieved by adopting a physical cutting method (such as a water knife, an air knife, a laser knife mold, a hardware prop and the like), and the first pole piece 10, the second pole piece 20 and the diaphragm are arranged in an overlapping manner, and a layer-by-layer selective cutting cannot be achieved by adopting a mechanical cutting method.

Example 1

Referring to fig. 5 to 7, the method specifically includes the following steps:

step S1, because the winding core of the current multi-tab winding technology is generally a same-side tab, the same-side tab is explained in this embodiment, as shown in fig. 5, a first pole piece 10, a separator, and a second pole piece 20 are wound to form a full-tab electric core 30A, the first pole piece 10 includes a first pole piece main body 101 and a first pole tab 102, and the second pole piece 20 includes a second pole piece main body 201 and a second pole tab 202, for safety, a pole piece covering redundancy design must exist in the current lithium ion battery winding core, especially in a region near a tab lead-out region, so in this example, the first pole tab 102 and the second pole tab 202 are arranged to partially protrude from the separator, specifically, the first pole tab 102 and the second pole tab 202 are arranged to protrude from the separator at the same height, the heights of the pole tabs formed by the pole pieces are ensured to be the same, the lengths of the first pole tab 102 and the second pole tab 202 are arranged to be different, and the lengths of the overlapping portions of the first pole tab 102 and the second pole tab 202 are also different, where the length of the first pole tab 102 and the overlapping portion of the separator 202 is D2.

Step S2, as shown in fig. 6, performing die cutting processing on the whole tab area 302 of the full tab electric core 30A, and after performing the die cutting processing, forming a multi-tab prototype, where the multi-tab prototype includes a first tab part 3021A, a second tab part 3022A, and an edge overlapping part 303, where:

each of the first tab part 3021A and the second tab part 3022A includes a plurality of layers of first tab 3021, a separator, and a second tab 3022, which are alternately and partially overlapped;

the edge overlap 303 includes a plurality of layers of first pole piece tabs 3021, separators, and second pole piece tabs 3022 alternately arranged to overlap;

specifically, in the multi-tab prototype formed after die cutting, the first tab part 3021A and the second tab part 3022A are still in a state where the first tab part 3021 and the second tab part 3022A are alternately overlapped in multiple layers, and the cut edge projections of the first tab part 3021, the second tab part 3022, and the diaphragm of the edge overlapping part 303 completely overlap, that is, the coating redundancies D2 and D2 are both 0, so that the semi-finished multi-tab battery cell 30B manufactured by the full tab battery cell 30A with tabs on the same side through a simple cutting method cannot be manufactured into a rechargeable battery, and even if the multi-tab battery cell 30B is a tab on the opposite side, the manufactured semi-finished multi-tab battery cell 30B cannot be safely charged and discharged because the coating redundancies of the tab parts are zero.

Step S3, performing a regional and selective removal process on the overlapped multi-tab prototype, removing the separator and the second tab 3022 in the first tab portion 3021A to obtain a first tab overlapped only by the first tab 3021, and removing the separator and the first tab 3021 in the second tab portion 3022A to obtain a second tab overlapped only by the second tab 3022; referring to fig. 7, in this embodiment, the step S3 specifically includes the following steps:

step S3-1-1, soaking the first tab part 3021A and the entire edge overlap portion 303 in a first chemical solution S01, ensuring that the first tab part 3021 can be completely soaked in the first chemical solution S01, that is, the edge overlap portion 303 is soaked in the first chemical solution S01 with a height of D2, etching off the second tab part 3022 in the first tab part 3021A and the edge overlap portion 303, leaving the first tab part 3021 and the separator, forming a first tab part in the first tab part 3021A with the first tab part 3021 and the separator, and forming a first tab part in the edge overlap portion 303 with a height of D2 to cover the first tab part 3021;

step S3-1-2, immersing the second pole ear 3022A and a part of the edge overlapping portion 303 in a second chemical liquid S02 to ensure that the second pole ear 3022 can be entirely immersed in the second chemical liquid S02, that is, the edge overlapping portion 303 is immersed in the second chemical liquid S02 at a height d2, etching off the first pole ear 3021 in the second pole ear 3022A and the edge overlapping portion 303, leaving the second pole ear 3022 and the diaphragm, forming a second pole ear in the second pole ear 3022A, leaving the second pole ear 3022 and the diaphragm, and forming a second pole ear 3022 with a height d2 in the edge overlapping portion 303 to cover the redundancy.

In this embodiment, the effect of removing the delamination is achieved by using a chemical etching method, the substrate used for the first electrode sheet 10 is generally a copper foil, the substrate used for the second electrode sheet 20 is generally an aluminum foil, and the chemical reaction properties of the copper foil and the aluminum foil are significantly different, and different chemical liquids can be respectively configured by using the chemical properties, specifically, the first chemical liquid S01 can be a dilute hydrochloric acid solution or a sodium hydroxide solution, and these chemical liquids can react with the aluminum base, so as to achieve the purpose of removing the aluminum base tab, so that the first electrode tab 3021A and the second electrode tab 3022 in the edge overlapping portion 303 can be etched by using the first chemical liquid S01, the second chemical liquid S02 can be concentrated nitric acid, these chemical liquids can react with the copper base, so as to achieve the purpose of removing the copper base electrode tab, so that the second electrode tab 3022A and the first electrode tab 3021 in the edge overlapping portion 303 can be etched by using the second chemical liquid S02.

In the embodiment, the method further comprises the step S3-1-3 of cleaning the edges of the first lug and the second lug after the first lug and the second lug are obtained, and removing the residual first chemical liquid S01 and the residual second chemical liquid S02;

specifically, the edge cleaning is performed by using a third chemical solution S03, where the third chemical solution S03 is an organic solvent, such as xylene, tetralin, decahydronaphthalene, and the like, and the organic solvent does not affect the first tab and the second tab, but can react with the separator, so that the separator at the first tab and the second tab can be corroded and removed while cleaning.

Example 2

Based on the preparation method of the present invention, an improved scheme is also proposed in this embodiment, which is shown in fig. 8 and 9, and specifically includes the following steps:

before the step S1, performing pre-damage treatment on the first pole piece 10 and the second pole piece 20 respectively, and forming a first tab pre-damage 102S and a second tab pre-damage 202S on the first pole piece 10 and the second pole piece 20 respectively, where the first tab pre-damage 102S and the second tab pre-damage 202S are larger than a target tab width, specifically, the pre-damage treatment does not cut off the first pole piece 10 and the second pole piece 20, the first tab pre-damage 102S and the second tab pre-damage 202S are both arranged to extend along the pole piece winding direction, and the pre-damage size is arranged to occupy a smaller proportion of the whole winding core width size, so that the pre-damage treatment is performed before winding, which can meet the local pre-damage requirement, and can not affect the winding speed and the quality of the whole tab due to an excessively large and overweight wound.

In this embodiment, step S1 and step S2 are the same as those in embodiment 1, and are not described herein, and step S3 is different from embodiment 1, and specifically includes the following steps:

step S3-2-1, the first tab pre-damage 102S and the second tab pre-damage 202S are respectively broken and removed along the first tab pre-damage 102S and the second tab pre-damage 202S to form a first tab retaining the first tab 3021 and a second tab retaining the second tab 3022, in this embodiment, since the pre-damage treatment is performed on the first tab 10 and the second tab 20 before step S1, and after winding and die cutting, only the positions of the first tab pre-damage 102S and the second tab pre-damage 202S need to be re-treated, including repeated bending, high-frequency oscillation and other methods, the breaking removal of the first tab pre-damage 102S and the second tab pre-damage 202S is realized, so that the target effect that only the first tab 3021 is left in the first tab portion 3021A, and only the second tab 3022A remains in the second tab portion 3022A is realized.

Specifically, according to the actual situation, the method of pre-damage treatment may adopt a mechanical cutting method, which may cut local linear micropores, and a chemical etching method, which may spray chemical etching liquid linearly.

Example 3

The invention also discloses a multi-tab battery cell which is prepared based on the preparation methods of the embodiment 1 and the embodiment 2.

It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications therefrom are within the scope of the invention.

Claims

1. A preparation method of a multi-tab battery cell is characterized by comprising the following steps:

s1, preparing a first pole piece, a diaphragm and a second pole piece to form a full-lug battery cell;

2. The method for preparing a multi-tab battery cell according to claim 1, wherein the method comprises the following steps: in step S1, when forming a full tab electric core, the first pole piece and the second pole piece partially protrude from the diaphragm in the tab area.

3. The method for preparing a multi-tab cell of claim 2, wherein: in step S2, after the die-cutting process is performed, the multi-tab prototype includes a first tab portion, a second tab portion, and an edge overlapping portion, wherein:

the edge overlapping part comprises a plurality of layers of first pole piece tabs, a diaphragm and second pole piece tabs which are arranged in an alternating and all-overlapping mode.

4. The method for preparing a multi-tab cell of claim 3, wherein the method comprises the following steps: in step S3, the method specifically includes the following steps:

s3-1-1, soaking the first pole lug part and all the edge overlapped parts in a first chemical liquid, removing a second pole lug positioned in the first pole lug part and the edge overlapped parts, reserving the first pole lug and a diaphragm, forming a first pole lug reserving the first pole lug and the diaphragm at the first pole lug part, and forming a first pole lug cladding redundancy at the edge overlapped parts, namely enabling the edge overlapped parts of the first pole lug to protrude out of the connection position of the first pole lug and the first pole piece;

and S3-1-2, soaking the second pole piece part and part of the edge overlapping part in a second chemical solution, corroding a first pole piece lug in the second pole piece part and the edge overlapping part, reserving the second pole piece lug and a diaphragm, forming a second pole piece lug reserving the second pole piece lug and the diaphragm on the second pole piece part, and forming a second pole piece lug cladding redundancy on the edge overlapping part, namely enabling the edge overlapping part of the second pole piece to protrude out of the connecting position of the second pole piece and the second pole piece.

5. The method for preparing a multi-tab battery cell according to claim 4, wherein the method comprises the following steps: and the method further comprises the step S3-1-3 of cleaning the edges of the first tab and the second tab after the first tab and the second tab are obtained, and removing the residual first chemical liquid and second chemical liquid.

6. The method for preparing a multi-tab battery cell according to claim 5, wherein the method comprises the following steps: in step S3-1-3, edge cleaning is performed by using a third chemical solution, and the diaphragms at the first lug and the second lug are etched and removed while cleaning.

7. The method for preparing a multi-tab cell of claim 1, wherein: before the step S1, pre-damage treatment is respectively carried out on the first pole piece and the second pole piece, and a first pole ear pre-damage and a second pole ear pre-damage which can cover the width of a target pole ear are respectively formed on the first pole piece and the second pole piece.

8. The method for preparing a multi-tab cell of claim 7, wherein the method comprises the following steps: in step S3, the method specifically includes the following steps:

9. The method for preparing a multi-tab cell of claim 7, wherein the method comprises the following steps: the method for pre-damage treatment comprises local linear micropore cutting or linear chemical corrosion.

10. The utility model provides a many utmost point ear electricity core which characterized in that: prepared by the process of any one of claims 1 to 9.