阅读说明：本技术 一种用于卷绕式多极耳电芯的极片的制备方法、极片及电芯 (Preparation method of pole piece for winding type multi-tab battery cell, pole piece and battery cell ) 是由 郑开元 韩冰 纪荣进 李聪 郑明清 陈杰 李载波 杨山 于 2020-05-22 设计创作，主要内容包括：本发明属于锂离子电池技术领域,尤其涉及一种用于卷绕式多极耳电芯的极片的制备方法,在集流体的表面间隙涂覆活性物质层和连续涂覆绝缘涂层,绝缘涂层邻接于靠近极耳部一侧的活性物质层；去除集流体间隙空箔区边缘已涂覆的绝缘涂层；沿绝缘涂层模切极耳部后得到用于卷绕式多极耳电芯的极片。本发明中在活性物质层的和集流体边缘空箔区之间连续涂覆绝缘涂层,沿绝缘涂层激光模切得到箔材极耳,减少了毛刺的产生,进一步提升了电芯的安全性能。本发明在去除集流体间隙空箔区已涂覆的绝缘涂层后,在卷绕后得到多极耳电芯时,提高了电芯的能量密度。(The invention belongs to the technical field of lithium ion batteries, and particularly relates to a preparation method of a pole piece for a winding type multi-tab battery cell, wherein an active substance layer and an insulating coating are coated on the surface clearance of a current collector, and the insulating coating is adjacent to the active substance layer close to one side of a tab part; removing the insulating coating coated on the edge of the current collector gap hollow foil area; and die-cutting the pole lug part along the insulating coating to obtain the pole piece for the winding type multi-pole-lug battery cell. According to the invention, the insulating coating is continuously coated between the active material layer and the current collector edge empty foil area, and the foil tab is obtained by laser die cutting along the insulating coating, so that the generation of burrs is reduced, and the safety performance of the battery cell is further improved. After the insulating coating coated on the empty foil area of the current collector gap is removed, the energy density of the battery cell is improved when the multi-tab battery cell is obtained after winding.)

1. A preparation method of a pole piece for a winding type multi-pole-lug battery cell is characterized by comprising the following operations:

coating an active material layer in a surface gap of a current collector and continuously coating an insulating coating, wherein the insulating coating is adjacent to the active material layer on one side close to a polar ear part;

removing the insulating coating coated on the edge of the current collector gap hollow foil area;

and die-cutting the pole lug part along the insulating coating to obtain the pole piece for the winding type multi-pole-lug battery cell.

2. The method for preparing a pole piece for a wound multi-tab cell according to claim 1, wherein the active material layer is a positive active material layer or a negative active material layer.

3. The method of claim 1, wherein the insulating coating comprises an alumina ceramic coating or an alumina-titania ceramic coating.

4. The method for preparing the pole piece for the wound multi-pole tab battery cell of claim 1, wherein the insulating coating coated on the edge of the current collector gap hollow foil area is removed by a scraper or a hollow adsorption assembly.

5. The method of claim 1, wherein the active material layer and the insulating coating are applied simultaneously.

6. The preparation method of the pole piece for the wound multi-pole tab battery cell of claim 1, wherein the thickness of the insulating coating is 30-50 μm.

7. The method of claim 1, further comprising centrally slitting the active material layer after removing the insulating coating applied to the current collector gap open foil area.

8. The method of claim 1, further comprising a metal strap tab welded to a foil tab formed after die cutting the tab portion.

9. A pole piece for a wound multi-tab cell, prepared by the method of any of claims 1-8 for making a pole piece for a wound multi-tab cell.

10. A wound multi-tab cell comprising the pole piece of claim 9 for a wound multi-tab cell.

Technical Field

The invention belongs to the technical field of lithium ion batteries, and particularly relates to a preparation method of a pole piece for a winding type multi-pole-lug battery cell, a pole piece for the winding type multi-pole-lug battery cell and the winding type multi-pole-lug battery cell.

Background

Lithium ion batteries have the advantages of light weight, good safety performance and the like, so that the lithium ion batteries are applied to the fields of mobile electronic equipment such as Bluetooth headsets, mobile phones, notebook computers, tablet computers and cameras, portable mobile power supplies and the like. Meanwhile, lithium ion batteries have also been applied in the fields of electric motorcycles, electric automobiles, and the like in batches.

People put forward higher requirements on energy density, rate discharge and discharge temperature rise of the lithium ion battery, the thickness of the battery is increased, the lengths of the positive electrode and the negative electrode of the battery are increased, if a single tab form is adopted, the internal resistance of the battery is large, the polarization of the battery is serious during discharge, the service life and the safety performance of the battery are influenced, and therefore the multi-tab battery is more and more widely applied.

The development of the multi-tab technology greatly improves the energy density of the lithium ion battery and plays a role in promoting the development of the lithium battery industry in China. The current multi-tab battery core can reserve a current collector edge empty foil area (also called as a tab part) during pole piece coating, and after rolling and cutting, the current collector edge empty foil area is cut to form a plurality of tabs before winding.

However, the current preparation process of the winding type multi-tab battery cell has the following problems:

1) the coating of the active substance layer in the multi-tab battery cell pole piece generally adopts continuous coating, and the precision in slitting is not high enough;

2) when the coating of active material layer in the multi-tab electric core pole piece adopts continuous coating, because the pole piece afterbody does not include empty paper tinsel district, need close to the end with the diaphragm at last, correspondingly, still need increase round negative pole active material layer and adhesive tape, increased the thickness of electric core, reduced the energy density of electric core in other words.

3) The empty foil district in mass flow body edge all can exist at the both ends on the active material layer on the pole piece, and the empty foil district in mass flow body edge on one side wherein can cross cutting into the utmost point ear, however, the empty foil district in cross cutting mass flow body edge probably produces the burr, and the diaphragm is punctureed to the burr probably produces the safety risk.

Disclosure of Invention

One of the objects of the present invention is: aiming at the defects of the prior art, the preparation method of the pole piece for the winding type multi-pole-lug battery cell is provided, which can improve the pole piece slitting precision and the energy density and the safety performance of the battery cell.

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

a preparation method of a pole piece for a winding type multi-pole-lug battery cell comprises the following operations:

coating an active material layer in a surface gap of a current collector and continuously coating an insulating coating, wherein the insulating coating is adjacent to the active material layer on one side close to a polar ear part;

removing the insulating coating coated on the edge of the current collector gap hollow foil area;

and die-cutting the pole lug part along the insulating coating to obtain the pole piece for the winding type multi-pole-lug battery cell.

As an improvement of the preparation method of the pole piece for the winding type multi-pole-ear battery cell, the active substance layer is a positive active substance layer or a negative active substance layer. Preferably, the active material layer is a positive electrode active material layer. In the preparation process of pole piece, generally use laser cutting or metal cutting die to cut out utmost point ear, when utmost point ear size needs the change, the metal cutting die also needs corresponding remodelling, however, the metal cutting die remodelling expense is higher, can reduce production efficiency moreover, consequently, generally adopts the laser mould to cut out utmost point ear. Due to the characteristics of the anode active material layer material, when the anode active material layer is cut by laser, large burrs are generated at the cutting position, and the burrs are not processed and can puncture the diaphragm to cause short circuit inside the battery core.

As an improvement of the preparation method of the pole piece for the winding-type multi-pole-ear cell, the insulating coating comprises an alumina ceramic coating or an alumina-titania ceramic coating. The insulating coating comprises but is not limited to an alumina ceramic coating or an alumina-titania ceramic coating, has no conductivity, has stable chemical properties, is not easy to participate in electrochemical reaction inside the battery cell, and can be flexibly arranged according to actual conditions.

As an improvement of the preparation method of the pole piece for the winding type multi-pole-ear battery core, the insulating coating coated on the edge of the empty foil area of the current collector gap is removed through a scraper blade or a hollow adsorption assembly. Because the intermittent coating of the active material layer and the intermittent coating of the insulating coating can not be realized at the same time at present, the safe coating needs to be continuously coated first, and then the insulating coating coated on the edge of the empty foil area of the current collector gap needs to be removed.

As an improvement of the preparation method of the pole piece for the winding type multi-pole-ear battery cell, the active substance layer and the insulating coating are coated simultaneously. Wherein, the intermittent coating of the active material layer and the continuous coating of the insulating coating share a set of die heads, and the simultaneous coating is realized.

As an improvement of the method for manufacturing a pole piece for a wound multi-tab cell, one surface of the current collector gap empty foil area includes a current collector single-sided empty foil area and a current collector first double-sided empty foil area, and the opposite surface of the current collector gap empty foil area includes a current collector second double-sided empty foil area. When the active material layer is coated in the clearance, because the length of the empty foil district in the clearance on two sides of the mass flow body is different, the empty foil district in the mass flow body single face and the empty foil district in the mass flow body double-sided can be formed on two sides of the pole piece. After winding, the end of the double-sided empty foil area of the current collector is used, and the thickness of the insulating coating is equivalently cancelled due to the fact that the insulating coating does not exist in the double-sided empty foil area of the current collector, so that the energy density of the battery cell is improved.

As an improvement of the preparation method of the pole piece for the winding type multi-pole-ear battery cell, the thickness of the insulating coating is 30-50 μm. Preferably, the thickness of the insulating coating is 30 μm, 35 μm, 40 μm, 45 μm or 50 μm. Further preferably, the thickness of the insulating coating is 40 μm.

The improvement of the preparation method of the pole piece for the winding type multi-pole-ear battery cell, which is disclosed by the invention, also comprises a rolling operation after coating.

The improvement of the preparation method of the pole piece for the winding type multi-pole-ear battery cell is that after the insulating coating coated on the empty foil area of the current collector gap is removed, the active material layer is cut in the middle. In the prior art, after an active material layer is coated, the current collector edge empty foil areas on two sides of the active material layer are cut to form a primary pole piece. According to the invention, the active substance layer is cut in the center by adopting the metal cutting die, which is equivalent to removing the blank foil area at the edge of the current collector at one side of the primary pole piece, so that the energy density of the battery cell is improved.

The improved preparation method of the pole piece for the winding type multi-pole-lug battery cell further comprises a metal strip pole lug, wherein the metal strip pole lug is welded on a foil pole lug formed after the pole lug part is subjected to die cutting.

The second objective of the present invention is to provide a pole piece for a wound multi-tab battery cell, which is prepared by the method described in any one of the above descriptions.

The third objective of the present invention is to provide a winding type multi-tab battery cell, which includes the above-mentioned pole piece for the winding type multi-tab battery cell. The width of the winding type multi-lug battery cell is 20-200 mm, the height of the winding type battery cell is 30-200 mm, and the thickness of the winding type battery cell is 2-20 mm. The shell of the winding type multi-lug battery cell comprises a square battery cell, a soft-package battery cell or a steel shell cylindrical battery cell.

Compared with the prior art, the beneficial effects of the invention include but are not limited to:

1) in the prior art, for a multi-tab battery cell pole piece, an active material layer is usually obtained by adopting a continuous coating mode, and errors can be generated during slitting due to the absence of a gap empty foil area. Before the active material layer is coated intermittently, the gap coating size is preset on the surface of the current collector, and the gap is cut according to the gap empty foil area during cutting. Therefore, the cutting precision of the invention is higher.

2) The multi-tab battery cell prepared by continuously coating the active substance layer is finished by two circles of diaphragms after winding because no empty foil area exists on the surface of the pole piece, and the penultimate circle of the battery cell is provided with the negative active substance layer for preventing lithium precipitation and is pasted with adhesive tape. In the invention, the technical scheme of intermittently coating the active substance layer is adopted, the end of the current collector of the positive electrode is directly closed by half circle, the thickness of two circles of diaphragms, the thickness of one circle of the active substance layer of the negative electrode and the thickness of one layer of adhesive paper are reduced, which is equivalent to the improvement of the proportion of the active substance of the positive electrode, and therefore, the energy density is improved.

3) In the existing preparation method of the pole piece for the winding type multi-pole-lug battery cell, in order to avoid the generation of burrs, laser cutting is usually performed along the blank foil areas of the edges of the current collectors on the two long sides of the active material layer. In the invention, the insulating coating is continuously coated between the active substance layer and the current collector edge empty foil area, the foil electrode lug is obtained by laser die cutting along the insulating coating, and compared with the die cutting along the current collector edge empty foil area, the generation of burrs is reduced, and the safety performance of the battery cell is further improved.

4) In the invention, after the insulating coating coated on the empty foil area of the current collector gap is removed, when a multi-tab battery cell is obtained after winding, the insulating coating on the current collector head of the outermost circle of the battery cell is removed, and the thickness of the two layers of insulating coatings is reduced, so that the energy density of the battery cell is improved.

Drawings

Fig. 1 is a schematic structural diagram of a large pole piece in example 1.

Fig. 2 is a schematic structural diagram of the primary electrode sheet in example 1.

Fig. 3 is a schematic view showing the structure of the slitting and die-cutting method in example 1.

Fig. 4 is a schematic structural view of the final electrode sheet in example 1.

Fig. 5 is one of the schematic structural diagrams of the wound multi-tab cell in embodiment 2.

Fig. 6 is a second schematic structural diagram of a wound multi-tab cell in embodiment 2.

Fig. 7 is a schematic view of the coating and slitting of the pole piece in comparative example 1.

Fig. 8 is a cross-sectional view of the final pole piece of comparative example 2 with the insulating coating applied to leave empty foil areas at the edges of the current collector.

Fig. 9 is a schematic structural view of a cell prepared using the pole piece of comparative example 2.

In the figure: 1-current collector, 2-active material layer, 3-insulating coating, 11-pole ear part, 12-gap empty foil area, 10-large pole piece, 20-primary pole piece, 30-final pole piece, 121-current collector single-side empty foil area, 122-current collector first double-side empty foil area and 123-current collector second double-side empty foil area.

Detailed Description

In order to make the technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to specific embodiments and drawings in the specification, and it is obvious that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.