WO2022022324A1 - Bipolar current collector, pole pieces, and secondary battery - Google Patents

Abstract

Provided are a bipolar current collector (30), pole pieces (10) and a secondary battery. The bipolar current collector (30) comprises an insulating thin film layer (31), a positive electrode metal layer (32) and a negative electrode metal layer (33). The positive electrode metal layer (32) and the negative electrode metal layer (33) are respectively provided on two surfaces, which are oppositely provided in the thickness direction, of the insulating thin film layer (31), the positive electrode metal layer (32) has a first coating area (321) and a first electrode tab area (322), the thickness of the first electrode tab area (322) is greater than the thickness of at least a part of the first coating area (321), the negative electrode metal layer (33) has a second coating area (331) and a second electrode tab area (332), and the thickness of the second electrode tab area (332) is greater than the thickness of at least a part of the second coating area (331).

Description

Bipolar current collectors, pole pieces and secondary batteries

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based on the Chinese patent applications with application numbers of 202010740927.4 and 202021539705.8, and the application dates are on July 28, 2020, and claims the priority of the Chinese patent application. The entire content of the Chinese patent application is incorporated herein by reference .

technical field

The present application relates to the technical field of secondary batteries, and in particular, to a bipolar current collector, a pole piece and a secondary battery.

Background technique

In the composite current collector, the negative electrode current collector usually forms a copper metal layer on both sides of the polymer layer, and the positive electrode current collector usually forms an aluminum metal layer on both sides of the polymer layer, and then prepares the pole piece and the secondary battery.

In order to further improve the energy density of the battery, the prior art provides a bipolar current collector. A copper layer and an aluminum layer are respectively formed on the two surfaces of the insulating film layer. and preparation of secondary batteries. However, in the process of welding the tabs, the insulating film layer is easily welded through, thereby causing a short circuit between the copper layer and the aluminum layer.

SUMMARY OF THE INVENTION

The purpose of this application is to provide a bipolar current collector, a pole piece and a secondary battery, which can avoid the short circuit between the positive and negative electrodes, and can facilitate the connection between the tab and the current collector to be firmer, and can improve the Overcurrent capability at the tab connection.

In a first aspect, the present application provides a bipolar current collector, comprising an insulating film layer, a positive electrode metal layer and a negative electrode metal layer. The insulating film layer has oppositely arranged first and second surfaces along the thickness direction, the positive metal layer is arranged on the first surface, and the negative metal layer is arranged on the second surface. The positive electrode metal layer has a first coating area for coating the positive electrode active material and a first tab area for connecting the positive electrode tabs, and the thickness of the first tab area is greater than the thickness of at least part of the first coating area . The negative electrode metal layer has a second coating area for coating the negative electrode active material and a second tab area for connecting the negative electrode tabs, and the thickness of the second tab area is greater than the thickness of at least part of the second coating area .

The positive metal layer is used as the positive electrode of the current collector, and the negative electrode metal layer is used as the negative electrode of the current collector. When the first tab area of the positive electrode metal layer is connected to the positive electrode tab, since the thickness of the first tab area is relatively thick, it can be avoided that the insulating film layer is perforated when the positive electrode tab is connected, so that to a certain extent Avoid short-circuiting the positive and negative poles of the secondary battery.

When the second tab area of the negative electrode metal layer is connected to the negative electrode tab, since the thickness of the second tab area is relatively thick, it can be avoided to perforate the insulating film layer when connecting the negative electrode tab, so that to a certain extent Avoid short-circuiting the positive and negative poles of the secondary battery.

According to some embodiments of the present application, the first coating area includes a first sub-area and a second sub-area, the first sub-area is located on at least one side in the width direction of the second sub-area, the The thickness of the first sub-region is greater than the thickness of the second sub-region, and the thickness of the first tab region is greater than the thickness of the second sub-region and not lower than the thickness of the first sub-region;

The second coating area includes a third sub-area and a fourth sub-area, the third sub-area is located on at least one side in the width direction of the fourth sub-area, and the thickness of the third sub-area is greater than that of the fourth sub-area. The thickness of the fourth sub-region, the thickness of the second tab region is greater than the thickness of the fourth sub-region and not lower than the thickness of the third sub-region.

The thickness of the first sub-region and the third sub-region is relatively thick. After the active material layer is coated, on the one hand, the connection strength between the active material layer and the metal layer can be enhanced, and on the other hand, the active material layer can be coated. When the confluence on the metal layer reaches the position of the first sub-region close to the first tab area, the overcurrent capability of the two is stronger, which can make the current generated by the active material layer finally converge to the tab, and improve the pole piece Conductivity.

In addition, since the thickness of the first sub-region and the thickness of the second sub-region in the first coating area are different, a stepped surface can be formed between the first sub-region and the second sub-region, so as to increase the coating thickness in the first coating area. The contact area between the coated active material layer and the positive metal layer in the second coating area can improve the adhesion of the coated active material layer; since the thickness of the third sub-region in the second coating area is different from the thickness of the fourth sub-region, it can be A step surface is formed between the third sub-region and the fourth sub-region to increase the contact area between the coated active material layer coated in the second coating region and the negative electrode metal layer, thereby improving the adhesion of the coated active material layer. focus.

In some optional embodiments of the present application, the first sub-regions are two and are distributed on opposite sides of the second sub-region in the width direction, and the two first sub-regions are distributed near the the position of the first tab area and the position far from the first tab area; the third sub-areas are two and are distributed on opposite sides in the width direction of the fourth sub-area, and the two The third sub-regions are distributed at positions close to the second tab region and positions away from the second tab region. By setting the two first sub-regions with a larger thickness and the two third sub-regions with a larger thickness, after the active material layer is coated, on the one hand, the gap between the active material layer and the metal layer can be further enhanced. On the other hand, when the confluence on the metal layer coated with the active material layer reaches the position of the first sub-region close to the first tab region, the overcurrent capability of the two is stronger, which can make the active material layer generate The current will eventually converge to the pole ear, which improves the conductivity of the pole piece.

In some optional embodiments of the present application, the thickness of the first sub-region is consistent with the thickness of the first tab region, and the thickness of the third sub-region is consistent with the thickness of the second tab region . The arrangement can enhance the connection strength between the active material layer and the metal layer, can improve the flow-through capability, and can make the structure of the bipolar current collector simple.

In some optional embodiments of the present application, the width of the first sub-region is 1-5 mm, and the width of the third sub-region is 1-5 mm. So that the tab area can be effectively connected with the tab, and under the condition of ensuring the overcurrent capability between the tab and the tab area, the overcurrent capability between the thicker area and the thinner area in the coating area can be taken into account, and further Improve the conductivity of the pole piece.

In some optional embodiments of the present application, a fifth sub-region is further provided between the first sub-region and the second sub-region, and the fifth sub-region extends from the second sub-region to the The direction of the first sub-region gradually becomes thicker; a sixth sub-region is further provided between the third sub-region and the fourth sub-region, and the sixth sub-region extends from the fourth sub-region to the sixth sub-region. The direction of the three sub-regions gradually thickens. It can avoid the membrane surface defects such as wrinkles and bulges in the metal layer between the two sub-areas, and the gradually thicker area is coated with an active material layer, which can gradually increase the overcurrent capability of the coating area, so that the pole piece can be gradually strengthened. The electrical conductivity is stronger, and the electrical conductivity of each part can be satisfied.

According to some embodiments of the present application, the thickness of the first tab region is greater than the thickness of the first coating region, and the thickness of the second tab region is greater than the thickness of the second coating region. By setting the thicknesses of the first tab area and the second tab area to be larger, when the first tab area is connected to the positive tab and the second tab area is connected to the negative tab, the risk of perforation of the insulating film layer can be reduced, Thereby, the short circuit of the positive and negative electrodes of the secondary battery can be further avoided. In addition, the connection between the tabs and the current collector is more firm, and at the same time, the overcurrent capability at the connection of the tabs can be improved.

According to some embodiments of the present application, the maximum thickness difference between the first tab region and the first coating region is 1-400 nm, and the maximum thickness difference between the second tab region and the second coating region is 1-600 nm. Optionally, the maximum thickness difference between the first tab region and the first coating region is 100-300 nm, and the maximum thickness difference between the second tab region and the second coating region is 200-500 nm. It can make the flow capacity between the tab and the current collector better, and the energy density of the battery is higher.

According to some embodiments of the present application, the thickness of the first coating region is 20-1500 nm, the thickness of the first tab region is 30-2000 nm; the thickness of the second coating region is 30-2500 nm, and the thickness of the second tab region is 30-2500 nm. Thickness is 50-3000nm. At the first coating area and the second coating area, the current collecting capacity of the positive and negative electrodes can be satisfied respectively, and at the first tab area and the second tab area, the current collecting capacity of the positive and negative electrodes can be satisfied respectively.

According to some embodiments of the present application, the first surface has a first blank area and a first metal area covered by the positive electrode metal layer, and the second surface has a second blank area and is covered by the negative electrode metal layer the second metal zone;

Wherein, in the thickness direction of the insulating film layer, at least part of the first tab area is disposed opposite to the second blank area, and at least part of the second tab area is opposite to the first blank area Relative settings.

When the first tab area of the positive electrode metal layer is connected to the positive electrode tab, at least part of the first tab area is disposed opposite to the second blank area, even if the first tab area and the positive electrode tab are welded or Other connection methods cause the insulating film layer to be damaged and perforated, but since at least part of the backside of the first tab area is not provided with a negative electrode metal layer, the risk of conduction between the positive electrode metal layer and the negative electrode metal layer can be reduced; When the second tab area is connected to the negative electrode tab, at least part of the second tab area is disposed opposite to the first blank area, even if the second tab area and the negative electrode tab are welded or connected by other means to make the insulating film The layer is damaged and perforated, but since at least part of the back of the second tab area is not provided with a positive metal layer, the risk of conduction between the negative metal layer and the positive metal layer can be reduced; thus, the risk of short circuit between the positive and negative electrodes can be reduced, and to a certain extent, avoid The positive and negative electrodes of the secondary battery are short-circuited.

In some optional embodiments of the present application, the projection of the first tab area on the reference surface is located within the projection of the second blank area on the reference surface, and the second tab area is on the reference surface The projection of the surface is located within the projection of the first blank area on the reference surface, and the reference surface is perpendicular to the thickness direction of the insulating film layer.

By making the projection of the first tab area on the reference surface within the projection of the second blank area on the reference surface, this arrangement can make the entire backside of the first tab area not provided with a negative metal layer, and by making the second tab area The projection of the area on the reference surface is located within the projection of the first blank area on the reference surface, so that the whole backside of the second tab area is not provided with a positive metal layer; these settings can better reduce the negative electrode metal layer and the positive electrode metal layer. The risk of layer conduction can be better reduced, and the short circuit of the positive and negative electrodes of the secondary battery can be better avoided.

Optionally, the projection of the first tab region on the reference surface is spaced apart from the projection of the negative electrode metal layer on the reference surface, and the projection of the second tab region on the reference surface is spaced from the positive electrode. The projections of the metal layers on the reference plane are spaced apart.

By making the projection of the first tab region on the reference surface and the projection of the negative electrode metal layer on the reference surface spaced apart, not only can the entire back surface of the first tab region not be provided with a negative electrode metal layer, but also the negative electrode metal layer and the The backside of a tab area is spaced at a certain distance; at the same time, by making the projection of the second tab area on the reference surface and the projection of the positive metal layer on the reference surface spaced apart, not only can the entire backside of the second tab area be uniform No positive electrode metal layer is provided, and the positive electrode metal layer is spaced a certain distance from the back of the second tab area; these settings can further reduce the risk of conduction between the negative electrode metal layer and the positive electrode metal layer, thereby further reducing the positive and negative electrode short circuit To a greater extent, the short circuit of the positive and negative electrodes of the secondary battery can be better avoided.

In some optional embodiments of the present application, along the width direction of the insulating film layer, the first blank area and the second blank area are respectively close to two edges of the insulating film layer.

So that the bipolar current collector has tabs on both sides in the width direction, one side of the bipolar current collector is connected to the positive electrode tab, and the other side is connected to the negative electrode tab, so as to avoid short circuit between the positive electrode tab and the negative electrode tab.

According to some embodiments of the present application, the positive electrode metal layer is a metal aluminum layer, and the negative electrode metal layer is a metal copper layer or a metal nickel layer.

In a second aspect, the present application provides a pole piece, comprising the above bipolar current collector, a positive electrode active material layer, a negative electrode active material layer, a positive electrode tab, and a negative electrode tab. The positive electrode active material layer is arranged in the first coating area, the negative electrode active material layer is arranged in the second coating area, the positive electrode tab is connected to the first tab area, and the negative electrode tab is connected to the second tab area.

The connection strength of the positive and negative electrode tabs is higher and the overcurrent capability of the connection between the positive and negative electrode tabs is stronger, and the connection between the positive and negative electrode tabs can effectively avoid conduction between the positive electrode metal layer and the negative electrode metal layer.

In a third aspect, the present application provides a secondary battery, comprising a plurality of the above-mentioned pole pieces and a plurality of separators, a separator is arranged between two adjacent pole pieces, and a positive electrode active material layer and a negative electrode are respectively arranged on both sides of the separator active material layer. The electrical performance of the secondary battery is better.

Description of drawings

In order to illustrate the technical solutions of the embodiments of the present application more clearly, the following drawings will briefly introduce the drawings that need to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and therefore do not It should be regarded as a limitation of the scope. For those of ordinary skill in the art, other related drawings can also be obtained from these drawings without creative efforts, which also belong to the protection scope of the present application.

FIG. 1 is a schematic structural diagram of a cell stack provided by an embodiment of the present application;

2 is a schematic structural diagram of a pole piece provided in an embodiment of the present application;

3 is a schematic diagram of a first structure of a bipolar current collector provided by an embodiment of the present application;

FIG. 4 is a second structural schematic diagram of a bipolar current collector provided by an embodiment of the present application;

FIG. 5 is a third structural schematic diagram of the bipolar current collector provided by the embodiment of the present application;

6 is a schematic diagram of the fourth structure of the bipolar current collector provided by the embodiment of the present application;

FIG. 7 is a schematic diagram of a fifth structure of the bipolar current collector provided by the embodiment of the present application.

Reference number:

10-pole piece; 20-diaphragm; 30-bipolar current collector; 40-positive electrode active material layer; 50-negative electrode active material layer; 60-positive electrode tab; 70-negative electrode tab; 31-insulating film layer; 32 - positive metal layer; 33 - negative metal layer; 311 - first surface; 312 - second surface; 3111 - first metal area; 3112 - first blank area; 3121 - second metal area; 3122 - second blank area 321 - first coating area; 322 - first tab area; 331 - second coating area; 332 - second tab area; 3212 - first sub area; 3211 - second sub area; Three sub-areas; 3311 - the fourth sub-area; 3213 - the fifth sub-area; 3313 - the sixth sub-area.

detailed description

In order to make the purposes, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be described below with reference to the accompanying drawings in the embodiments of the present application.

The main part of the secondary battery is the cell, and the cell can be a cell stack (laminated battery) or a cell roll (wound battery). FIG. 1 is a schematic structural diagram of a cell stack provided by an embodiment of the present application. Referring to FIG. 1 , the cell stack includes a plurality of pole pieces 10 and a plurality of diaphragms 20 , and a diaphragm 20 is disposed between two adjacent pole pieces 10 .

FIG. 2 is a schematic structural diagram of a pole piece 10 provided by an embodiment of the present application. Referring to FIGS. 1 and 2 , the pole piece 10 includes a bipolar current collector 30 , a positive electrode active material layer 40 , a negative electrode active material layer 50 , a positive electrode tab 60 and a negative electrode tab 70 . The positive electrode active material layer 40 and the negative electrode active material layer 50 are respectively disposed on the coating area of the bipolar current collector 30 , and the positive electrode tab 60 and the negative electrode tab 70 are respectively connected to the tab area of the bipolar current collector 30 . A positive electrode active material layer 40 and a negative electrode active material layer 50 are provided on both sides of the separator 20, respectively.

FIG. 3 is a schematic diagram of a first structure of a bipolar current collector 30 provided by an embodiment of the present application. Referring to FIG. 3 , the bipolar current collector 30 includes an insulating film layer 31 , a positive electrode metal layer 32 and a negative electrode metal layer 33 .

In the embodiment of the present application, the insulating thin film layer 31 has a first surface 311 and a second surface 312 arranged opposite to each other along the thickness direction, the first surface 311 has a first metal area 3111 and a first blank area 3112, and the second surface 312 has a first surface 3111 and a first blank area 3112. Two metal regions 3121 and a second blank region 3122 . The positive metal layer 32 is disposed in the first metal region 3111 , and the negative metal layer 33 is disposed in the second metal region 3121 .

In the embodiment of the present application, the insulating film layer 31 is non-conductive. Alternatively, the material of the insulating film layer 31 may be a polymer insulating layer, such as polystyrene, polypropylene, polyester, polycarbonate, polytetrafluoroethylene , polyimide and other films; the material of the insulating film layer 31 can be synthetic fiber insulating paper, such as: aramid fiber paper, polyester fiber paper; the material of the insulating film layer 31 can be various insulating tapes and the like. The positive electrode metal layer 32 and the negative electrode metal layer 33 are respectively disposed on the first surface 311 and the second surface 312 of the insulating film layer 31 to avoid conduction between the positive electrode metal layer 32 and the negative electrode metal layer 33 .

Optionally, the positive electrode metal layer 32 is a metal aluminum layer, and the negative electrode metal layer 33 is a metal copper layer or a metal nickel layer. In the embodiment of the present application, the positive metal layer 32 is a metal aluminum layer to conduct the conduction of the positive current; the negative metal layer 33 is a metal copper layer to conduct the conduction of the negative current. In this application, the positive metal layer 32 is not limited to a metal aluminum layer, as long as the positive metal layer that can be used as a current collector is within the scope of protection of the present application; the negative metal layer 33 is not limited to a metal copper layer, as long as it can be used as a collector. The metal layer of the negative electrode of the fluid is all within the protection scope of the present application.

In the embodiment of the present application, the positive electrode metal layer 32 has a first coating area 321 and a first tab area 322 , the positive electrode active material layer 40 is disposed in the first coating area 321 , and the positive electrode tab 60 is connected to the first tab area 322. The negative electrode metal layer 33 has a second coating area 331 and a second tab area 332 , the negative electrode active material layer 50 is disposed on the second coating area 331 , and the negative electrode tab 70 is connected to the second tab area 332 . In order to achieve the coating of active substances and the connection of the tabs.

In the prior art, generally all aluminum metal layers are formed on the first surface 311 of the insulating film layer 31, and all copper metal layers are formed on the second surface 312, and then the positive electrode tab 60 is welded to the aluminum metal layer or the negative electrode is welded. When the tab 70 is welded with the copper metal layer, due to the high welding temperature, the insulating film layer 31 is easily welded through, so that the aluminum metal layer and the copper metal layer at the welding tab are conductively connected to form a short circuit.

In the present application, in the thickness direction of the insulating film layer 31 , at least part of the first tab region 322 is arranged opposite to the second blank region 3122 , and at least part of the second tab region 332 is arranged opposite to the first blank region 3112 . Wherein, at least a part of the first tab area 322 is disposed opposite to the second blank area 3122 , a part of the first tab area 322 may be disposed opposite to the second blank area 3122 , or the entire first tab area 322 may be disposed opposite to each other. It is arranged opposite to the second blank area 3122; at least part of the second tab area 332 is arranged opposite to the first blank area 3112, which may be a part of the second tab area 332 and the first blank area 3112. The second tab regions 332 are disposed opposite to the first blank regions 3112 .

According to the bipolar current collector 30 of the embodiment of the present application, the positive electrode metal layer 32 is used as the positive electrode of the bipolar current collector 30 , and the negative electrode metal layer 33 is used as the negative electrode of the bipolar current collector 30 . When the tab area 322 is connected to the positive tab 60, at least part of the first tab area 322 is disposed opposite to the second blank area 3122, even if the first tab area 322 and the positive tab 60 are welded or otherwise The connection method causes the insulating film layer 31 to be damaged and perforated, but since the negative metal layer 33 is not provided at least in part on the back of the first tab region 322, the risk of conduction between the positive metal layer 32 and the negative metal layer 33 can be reduced; When the second tab region 332 of the metal layer 33 is connected to the negative electrode tab 70, at least part of the second tab region 332 is arranged opposite to the first blank region 3112, even if the second tab region 332 is connected to the negative electrode. The lugs 70 damage the insulating film layer 31 through welding or other connection methods, but since the positive metal layer 32 is not provided at least in part on the back of the second tab region 332, the conduction between the negative metal layer 33 and the positive metal layer 32 can be reduced. Thereby, the risk of short circuit of positive and negative electrodes can be reduced, and the short circuit of positive and negative electrodes of the secondary battery can be avoided to a certain extent.

In some optional embodiments of the present application, referring to FIG. 3 and FIG. 5 , the projection of the first tab area 322 on the reference surface is located within the projection of the second blank area 3122 on the reference surface, and the second tab area 332 is referred to in The projection of the surface is within the projection of the first blank area 3112 on the reference surface, and the reference surface is perpendicular to the thickness direction of the insulating film layer 31 . By making the projection of the first tab region 322 on the reference surface within the projection of the second blank region 3122 on the reference surface, this arrangement can make the entire backside of the first tab region 322 not provided with the negative metal layer 33, and by making The projection of the second tab region 332 on the reference surface is located within the projection of the first blank region 3112 on the reference surface, so that the entire backside of the second tab region 332 is not provided with the positive metal layer 32; these settings may be better The risk of conduction between the negative electrode metal layer 33 and the positive electrode metal layer 32 can be effectively reduced, so that the risk of short circuit between the positive and negative electrodes can be better reduced, and the short circuit of the positive and negative electrodes of the secondary battery can be better avoided.

The projection of the first tab region 322 along the thickness direction of the insulating film layer 31 is located in the second blank region 3122 . The projection of the second tab region 332 along the thickness direction of the insulating film layer 31 is located in the first blank region 3112 . When connecting the tab area to the tab area, even if the insulating film layer 31 is destroyed and perforated by welding or other connection methods, the back surface of the tab area (in the film structure and the tab area) The other side of the corresponding position) is not provided with metal, so there is no problem of conduction between the negative electrode metal layer 33 and the positive electrode metal layer 32, thus avoiding the short circuit of the positive and negative electrodes.

Please continue to refer to FIG. 3 , the backside of the first surface 311 of the insulating film layer 31 where the first tab region 322 is provided is not provided with the negative metal layer 33 (as shown in FIG. A tab area 322, the bottom is the second blank area 3122, the second blank area 3122 is not provided with the negative metal layer 33; the position to the right of the dotted line 2, the top is the first blank area 3112, the positive metal layer 32 is not provided, the bottom is the second tab region 332).

It should be noted that the corresponding manner of the first tab region 322 and the second blank region 3122 is not limited to the corresponding manner in FIG. 3 . FIG. 4 is a schematic diagram of the second structure of the bipolar current collector 30 provided by the embodiment of the present application. Referring to FIG. 4 , the projection of the first tab area 322 on the reference surface may slightly exceed the outer edge of the projection of the second blank area 3122 on the reference surface, and the projection of the second tab area 332 on the reference surface may slightly exceed the projection of the first tab area 332 on the reference surface. The blank area 3112 is at the outer edge of the projection of the reference plane. The position of the first tab area 322 close to the first coating area 321 may extend a part toward the direction of the first coating area 321 , so that the position of the first tab area 322 close to the first coating area 321 corresponds to the lower part. A negative metal layer 33 is provided (as shown in FIG. 4 , the position on the left of the dotted line 3 is the first tab area 322 above, the second blank area 3122 and part of the second coating area 331 below, and the second blank area. The negative metal layer 33 is not provided at 3122, and the position corresponding to the first tab area 322 is not entirely the second blank area 3122, but there may be a part of the second coating area 331; the position on the right of the dotted line 4, the lower part is the second blank area 3122. The tab area 332 is above the first blank area 3112 and part of the first coating area 321. The positive metal layer 32 is not provided in the first blank area 3112, and the position corresponding to the second tab area 332 is not entirely the first The blank area 3112 may have part of the second coating area 331).

In other embodiments, FIG. 5 is a schematic diagram of a third structure of the bipolar current collector 30 provided by the embodiment of the present application. Please refer to FIG. 5 , the projection of the first tab region 322 on the reference surface is spaced apart from the projection of the negative electrode metal layer 33 on the reference surface, and the projection of the second tab region 332 on the reference surface and the projection of the positive metal layer 32 on the reference surface spaced apart. By making the projection of the first tab region 322 on the reference surface spaced apart from the projection of the negative electrode metal layer 33 on the reference surface, not only the backside of the first tab region 322 is not provided with the negative electrode metal layer 33, but also the negative electrode metal layer 33 is not provided. The metal layer 33 is spaced a certain distance from the back surface of the first tab region 322; at the same time, by making the projection of the second tab region 332 on the reference surface spaced apart from the projection of the positive metal layer 32 on the reference surface, it can not only make the The positive electrode metal layer 32 is not provided on the entire rear surface of the diode tab region 332, and the positive electrode metal layer 32 is spaced from the back surface of the second tab region 332 by a certain distance; these settings can further reduce the negative electrode metal layer 33 and the positive electrode metal layer. 32 conduction risk, so that the risk of short circuit of positive and negative electrodes can be further reduced, and to a greater extent, the short circuit of positive and negative electrodes of the secondary battery can be better avoided.

Please continue to refer to FIG. 5 , the position of the first blank area 3112 close to the first coating area 321 may extend toward the first coating area 321 , so that the width of the first blank area 3112 exceeds the second tab area 332 (As shown in FIG. 5 , at the position to the right of the dotted line 5, there is still a part of the second blank area 3122; at the position to the left of the dotted line 6, there is still a part of the excess first blank area 3112). This application does not limit the positional correspondence between the blank area and the tab area on the opposite two surfaces, as long as the tab area is connected, the blank area can be set to avoid the tab area and the metal on the back of the tab area. The turn-on solutions are all within the protection scope of the present application.

In order to form the bipolar current collector 30 structure, optionally, when depositing the positive electrode metal layer 32 on the first surface 311 of the insulating film layer 31, mask the first blank area 3112 of the first surface 311, and do not form The positive metal layer 32 is used to mask the porosity or transmittance of the first metal layer on the first surface 311 to form a first coating region 321 and a first tab region 322 with different thicknesses, and then the back surface is Metal layer settings.

For example: when depositing the metal layer, a baffle is set between the insulating film layer 31 and the metal source, the baffle includes a shielding part and a hollow part, and the baffle at the position corresponding to the first blank area 3112 (or the second blank area 3122 ) The board is completely covered, and there is no hollow part; the proportion of the hollow part of the baffle at the position corresponding to the first tab area 322 (or the second tab area 332 ) is larger than that of the first coating area 321 (or the second coating area 332 ). The proportion of the hollow portion of the baffle plate at the position corresponding to the region 331) forms the structure of the bipolar current collector 30 shown in FIG. 3 .

Optionally, the hollow part is a hole structure. In order to make the processing technology of the baffle simple, a round hole structure can be set on the baffle to form a hollow part, and the aperture size of each circular hole structure is the same. The circular hole structures at the ear area 322 are evenly distributed, and the circular hole structures at the baffle corresponding to the first coating area 321 are also uniformly distributed, and the number of circular hole structures at the baffle corresponding to the first tab area 322 is more than The number of the circular hole structures at the first coating area 321 of the baffle plate corresponds to the number of the metal layers with unequal thicknesses.

Of course, the shielding part of the baffle corresponding to the first tab region 322 can also be 0, and all are hollow parts, that is, the part corresponding to the first tab region 322 is not provided with a baffle, and the metal source is more plated on the insulating part. on the film layer 31 .

In the embodiment of the present application, along the width direction of the insulating film layer 31 , the first blank area 3112 and the second blank area 3122 are respectively located on both sides of the insulating film layer 31 . As shown in FIG. 3-FIG. 5, in the cross-sectional views of the bipolar current collector 30, the first blank area 3112 is on the right side of the figure, and the second blank area 3122 is on the left side of the figure, and they are arranged in a staggered manner. , which can make the preparation of the current collector simpler and the connection of the tabs more convenient.

Please continue to refer to FIGS. 1 and 2. After the current collectors shown in FIGS. 3 to 5 are prepared, the first tab area 322 on the left is all connected to the positive tab 60, and the second tab area 332 on the right is all connected to the negative electrode. The lugs 70, and then the positive pole lugs 60 on the left are collected on the positive connecting piece, and the negative pole lugs 70 on the right are gathered on the negative connecting piece, so as to realize the bilateral output of the poles, and avoid the connection of the positive and negative poles 70 when they are converged. Short circuit, further Short circuit of positive and negative poles is avoided.

Please continue to refer to FIGS. 3 to 5 , in the embodiment of the present application, the thickness of the first tab region 322 is greater than the thickness of at least part of the first coating region 321 , and the thickness of the second tab region 332 is greater than that of the second coating The thickness of at least part of the region 331 . The first coating area 321 and the second coating area 331 are mainly for conducting flow, and the thinner they are, the better the ability to conduct flow can be achieved. The thickness of the metal layer in the tab area is thicker, which can avoid perforating the insulating film layer when connecting the positive tab, and avoid short circuit of the positive and negative electrodes of the secondary battery from another level. By setting the thicknesses of the first tab area 322 and the second tab area 332 to be larger, when the first tab area 322 is connected to the positive tab 60 and the second tab area 332 is connected to the negative tab 70 , the thickness can be reduced. The risk of perforation of the insulating film layer 31 is reduced, thereby reducing the risk of contact conduction between the positive electrode metal layer 32 and the negative electrode metal layer 33, and to a certain extent, the short circuit of the positive and negative electrodes of the secondary battery can be avoided. In addition, the connection between the tabs and the current collector is more firm, and at the same time, the overcurrent capability at the connection of the tabs can be improved.

According to some embodiments of the present application, referring to FIGS. 1-3 , the thickness of the first tab region 322 is greater than that of the first coating region 321 , and the thickness of the second tab region 332 is greater than that of the second coating region 331 . By setting the thicknesses of the first tab area 322 and the second tab area 332 to be larger, when the first tab area 322 is connected to the positive tab 60 and the second tab area 332 is connected to the negative tab 70 , the thickness can be reduced. There is a risk of perforation of the insulating film layer 31, so that the short circuit of the positive and negative electrodes of the secondary battery can be further avoided. In addition, the connection between the tabs and the current collector is more firm, and at the same time, the overcurrent capability at the connection of the tabs can be improved.

According to some embodiments of the present application, the maximum thickness difference between the first tab region 322 and the first coating region 321 is 1-400 nm; the maximum thickness difference between the second tab region 332 and the second coating region 331 is 1-400 nm. 600nm. The function of the coating area and the function of the tab area in the metal layer can be fully exerted. Further, the maximum thickness difference between the first tab region 322 and the first coating region 321 is 100-300 nm; the maximum thickness difference between the second tab region 332 and the second coating region 331 is 200-500 nm.

The thickness of the first coating region 321 is 20-1500nm, the thickness of the first tab region 322 is 30-2000nm; the thickness of the second coating region 331 is 30-2500nm, and the thickness of the second tab region 332 is 50-2000nm. 3000nm.

In some possible embodiments, the thickness of the first coating region 321 is 1000 nm, the thickness of the first tab region 322 is 1300 nm, and the thickness difference between the first tab region 322 and the first coating region 321 is 300 nm; The thickness of the second coating region 331 is 2000 nm, the thickness of the second tab region 332 is 2500 nm, and the maximum thickness difference between the second tab region 332 and the second coating region 331 is 500 nm. This application is not limited.

According to some embodiments of the present application, referring to FIGS. 6 and 7 , the first coating region 321 includes a first sub-region 3212 and a second sub-region 3211 , and the first sub-region 3212 is located in the width direction of the second sub-region 3211 . On at least one side, the thickness of the first sub-region 3212 is greater than that of the second sub-region 3211 , the thickness of the first tab region 322 is greater than the thickness of the second sub-region 3211 and the thickness of the first tab region 322 is not lower than the thickness of the first tab region 322 Thickness of sub-region 3212. The second coating region 331 includes a third sub-region 3312 and a fourth sub-region 3311, the third sub-region 3312 is located on at least one side in the width direction of the fourth sub-region 3311, and the thickness of the third sub-region 3312 is greater than that of the fourth sub-region 3312 The thickness of the region 3311 and the thickness of the second tab region 332 are greater than the thickness of the fourth sub-region 3311 and the thickness of the second tab region 332 is not lower than the thickness of the third sub-region 3312 .

By making the thickness of the first sub-region 3212 and the third sub-region 3312 thicker, after the active material layer is coated, on the one hand, the connection strength between the active material layer and the metal layer can be enhanced, and on the other hand, it can be It further enhances the overcurrent capability and improves the electrical conductivity of the pole piece. In addition, since the thickness of the first sub-region 3212 of the first coating region 321 is different from the thickness of the second sub-region 3211, a stepped surface can be formed between the first sub-region 3212 and the second sub-region 3211 to increase the coating The contact area between the coating active material layer and the positive electrode metal layer 32 in the first coating region 321 can improve the adhesion of the coating active material layer; since the thickness of the third sub-region 3312 of the second coating region 331 is the same as The thickness of the fourth sub-region 3311 is different, a step surface can be formed between the third sub-region 3312 and the fourth sub-region 3311, and the coating active material layer and the negative electrode metal layer 33 coated on the second coating region 331 can be increased. Therefore, the adhesion of the active material layer can be improved.

In some optional embodiments of the present application, referring to FIG. 6 and FIG. 7 , there are two first sub-regions 3212 and the two first sub-regions 3212 are distributed on opposite sides of the second sub-region 3211 in the width direction, The two first sub-regions 3212 are distributed at positions close to the first tab region 322 and positions far from the first tab region 322 . There are two third sub-regions 3312 and the two third sub-regions 3312 are distributed on opposite sides of the fourth sub-region 3311 in the width direction, and the two third sub-regions 3312 are distributed near the second tab region 332 and a position away from the second tab region 332 . By setting the two first sub-regions 3212 with a larger thickness and the two third sub-regions 3312 with a larger thickness, after the active material layer is coated, on the one hand, it is possible to further enhance the active material layer and the metal layer. On the other hand, when the confluence on the metal layer coated with the active material layer reaches the position of the first sub-region close to the first tab region, the overcurrent capability of the two is stronger, which can make the active material The current generated by the layer is finally concentrated to the tab, which improves the electrical conductivity of the pole piece.

In some optional embodiments of the present application, referring to FIGS. 6 and 7 , the thickness of the first sub-region 3212 is consistent with the thickness of the first tab region 322 , and the thickness of the third sub-region 3312 is the same as the thickness of the second tab region 332 thickness is the same. The arrangement can enhance the connection strength between the active material layer and the metal layer, can improve the flow-through capability, and can make the structure of the bipolar current collector simple.

FIG. 6 is a schematic diagram of a fourth structure of the bipolar current collector 30 provided by the embodiment of the present application. Please refer to FIGS. 2 and 6 , the first coating area 321 includes a first sub-area 3212 and a second sub-area 3211 . The first sub-area 3212 is located close to the first tab area 322 and away from the first tab area 322, the second sub-region 3211 is located between the two first sub-regions 3212 (as shown in FIG. 2 and FIG. 6 correspondingly, in the positive electrode metal layer 32 coated with the positive electrode active material, the thinner region is the second sub-region 3212). The thickness of the first sub-region 3212 is the same as that of the first tab region 322 , and the thickness of the first sub-region 3212 is greater than that of the second sub-region 3211 .

The positive electrode active material layer 40 is disposed on the second sub-region 3211 and the first sub-region 3212 on both sides of the second sub-region 3211, which can make the bonding effect between the positive electrode active material layer 40 and the positive electrode metal layer 32 better (coating When the positive electrode active material layer 40 is coated, as a whole, it is not only coated on the thinner positive electrode metal layer 32 area, but also on the thicker positive electrode metal layer 32 area. There will be a stress, so that the adhesion of the positive electrode active material layer 40 is better). And the thickness of the first sub-region 3212 close to the first tab region 322 is thicker, and the coating of the positive electrode active material layer 40 can make the overcurrent between the thinner region of the coating region and the thicker region of the coating region. The ability is enhanced, thereby improving the conductivity of the entire pole piece 10, reducing the internal resistance of the battery cell, and improving the 3C capacity retention rate of the battery core.

The second coating area 331 includes a third sub-area 3312 and a fourth sub-area 3311. The third sub-area 3312 is a position close to the second tab area 332 and a position far from the second tab area 332. The fourth sub-area 3311 is located between the two third sub-regions 3312 , the thickness of the third sub-region 3312 is the same as that of the second tab region 332 , and the thickness of the third sub-region 3312 is greater than that of the fourth sub-region 3311 .

The negative electrode active material layer 50 is arranged on the fourth sub-region 3311 and on the third sub-region 3312 on both sides of the fourth sub-region 3311, so that the bonding effect between the negative electrode active material layer 50 and the negative electrode metal layer 33 can be better (coating When the negative electrode active material layer 50 is coated, as a whole, it is not only coated on the thinner negative electrode metal layer 33 area, but also on the thicker negative electrode metal layer 33 area. There will be a stress, so that the adhesion of the negative electrode active material layer 50 is better). And the thickness of the third sub-region 3312 close to the second tab region 332 is thicker, and coating the negative electrode active material layer 50 can make the overcurrent between the thinner region of the coating region and the thicker region of the coating region. The ability is enhanced, thereby improving the conductivity of the entire pole piece 10, reducing the internal resistance of the battery cell, and improving the 3C capacity retention rate of the battery core.

Please continue to refer to FIG. 6 , in the embodiment of the present application, the width a of the first sub-region 3212 is 1-5 mm. The width a of the first sub-region 3212 is the distance a between the boundary line between the first sub-region 3212 and the second sub-region 3211 on the left and the boundary line between the first sub-region 3212 and the first tab region 322 (see FIG. 6 ). a) on the left. The width of the first sub-area 3212 may also be the distance between the boundary line between the first sub-area 3212 and the second sub-area 3211 on the right and the boundary line between the first sub-area 3212 and the first blank area 3112 (see the right side of FIG. 6 ). a). The first sub-region 3212 on the left can not only improve the bonding force between the positive electrode metal layer 32 and the positive electrode active material layer 40, but also improve the overcurrent capability at this position. The first sub-region 3212 on the right is mainly for improving the positive electrode metal layer 32. The binding force with the positive electrode active material layer 40 .

The width b of the third sub-region 3312 is 1-5 mm. The width b of the third sub-region 3312 is the distance b between the boundary line between the third sub-region 3312 and the fourth sub-region 3311 on the right and the boundary line between the third sub-region 3312 and the second tab region 332 (see FIG. 6 ). center right b). The width of the third sub-area 3312 may also be the distance between the dividing line between the second blank area 3122 and the third sub-area 3312 and the dividing line between the third sub-area 3312 and the fourth sub-area 3311 on the left (as shown in the left side of FIG. 6 ) b). The third sub-region 3312 on the right can not only improve the bonding force between the negative electrode metal layer 33 and the negative electrode active material layer 50, but also improve the overcurrent capability at this position. The third sub-region 3312 on the left is mainly to improve the negative electrode metal layer 33. The binding force with the negative electrode active material layer 50 .

Further, the first sub-region 3212 close to the first tab region 322 and the third sub-region 3312 close to the second tab region 332 are coated with the active material layer, and it is not necessary to completely align the active material layer at a thicker surface. At the junction of the area and the thinner area, when coating the active material layer, you only need to coat the thinner area completely, and partially coat the thicker area close to the thinner area, that is, to complete the setting of the active material layer, The coating efficiency can be improved.

Optionally, the width a of the first sub-region 3212 is 2-4 mm, and the width b of the third sub-region 3312 is 2-4 mm. In some possible implementations, the width a of the first sub-region 3212 is 1 mm, 2 mm, 3 mm, 4 mm or 5 mm; the width b of the third sub-region 3312 is 1 mm, 2 mm, 3 mm, 4 mm or 5 mm.

It should be noted that: the width of the first sub-region 3212 and the width of the second sub-region 3211 may be consistent or inconsistent; the widths of the two first sub-regions 3212 may be consistent or inconsistent; the widths of the two third sub-regions 3312 The width can be the same or not. This application does not limit it, as long as a thicker sub-region can be formed to increase the bonding force between the active material layer and the metal layer, or/and the sub-region that increases the overcurrent capability of the metal layer is within the protection scope of this application. Inside.

In order to realize the above structure, the method is as follows: the hollow portion of the baffle at the positions corresponding to the first tab region 322 (or the second tab region 332 ) and the first sub-region 3212 (or the third sub-region 3312 ) The proportion is larger than that of the hollow portion of the baffle at the position corresponding to the second sub-region 3211 (or the fourth sub-region 3311 ), thereby forming the structure of the bipolar current collector 30 shown in FIG. 6 .

FIG. 7 is a fifth structural schematic diagram of the bipolar current collector 30 provided by the embodiment of the present application. Referring to FIG. 7 , a fifth sub-region 3213 is further disposed between the first sub-region 3212 and the second sub-region 3211 , and the fifth sub-region 3213 gradually thickens along the direction from the second sub-region 3211 to the first sub-region 3212 . The layer structure of the positive electrode metal layer 32 can be changed from left to right to be thick, gradually thinner, thinner, gradually thicker and thicker, which can avoid the occurrence of wrinkles, bulges and other membrane defects in the positive electrode metal layer 32 of the current collector. Further increasing the bonding force between the negative electrode active material layer 50 and the positive electrode metal layer 32 can also further increase the electrical conductivity of the pole piece 10 , so that the electrical conductivity of each part of the pole piece 10 is satisfied.

Please continue to refer to FIG. 7 , a sixth sub-region 3313 is further disposed between the third sub-region 3312 and the fourth sub-region 3311 , and the sixth sub-region 3313 gradually thickens along the direction from the fourth sub-region 3311 to the third sub-region 3312 . The negative electrode metal layer 33 can be changed from left to right to be thick, gradually thinner, thinner, gradually thicker and thicker, and the negative electrode metal layer 33 of the current collector can be prevented from appearing wrinkles, bulges and other membrane surface defects, and can Further increasing the bonding force between the positive electrode active material layer 40 and the negative electrode metal layer 33 can also further increase the electrical conductivity of the pole piece 10 , so that the electrical conductivity of each part of the pole piece 10 is satisfied.

Further, the aforementioned gradual thickening may be that a surface of the gradually thickened region away from the insulating film layer 31 forms an inclined plane. In order to realize the above structure, the method is as follows: the hollow portion of the baffle at the positions corresponding to the first tab region 322 (or the second tab region 332 ) and the first sub-region 3212 (or the third sub-region 3312 ) The proportion is larger than the proportion of the hollow part of the baffle at the position corresponding to the second sub-region 3211 (or the fourth sub-region 3311 ), and the fifth sub-region 3213 (or the sixth sub-region 3313 ), the proportion of the hollow part gradually increase to form the structure of the bipolar current collector 30 shown in FIG. 7 .

In other embodiments, the aforementioned gradually thickening may also be a surface of the gradually thickening region (the fifth sub-region 3213 or/and the sixth sub-region 3313 ) that is far away from the insulating film layer 31 to form a circular arc surface, The arc surface is convex toward the direction away from the insulating film layer 31 ; or a surface of the gradually thickened region away from the insulating film layer 31 forms an arc surface, and the arc surface is concave toward the direction close to the insulating film layer 31 . This application does not limit it, as long as a gradually thicker structure can be formed to satisfy the electrical conductivity of each part of the metal layer, it is within the scope of protection of the present application.

The beneficial effects of the bipolar current collector 30 and the pole piece 10 provided by the embodiments of the present application include:

(1) When the tab area is connected to the tab (for example, by welding), even if the insulating film layer 31 is damaged due to the connection process, due to the setting of the blank area on the back of the tab area, aluminum metal can be effectively avoided. The conduction between the layer and the copper metal layer can effectively avoid the short circuit of the positive and negative electrodes.

(2) The thickness of the tab area is thicker, which can avoid perforating the insulating film layer 31 when connecting the tab, thereby avoiding the conduction between the aluminum metal layer and the copper metal layer, and avoiding the positive and negative electrodes from another level. short circuit.

(3) The setting of the thicker sub-region near the tab region can not only increase the bonding force between the active material layer and the metal layer, but also increase the cross-linking between the thinner metal layer and the thicker metal layer. flow capability. The arrangement of the thicker sub-regions away from the tab region can increase the bonding force between the active material layer and the metal layer.

(4) It is a gradual thickening process from a thinner sub-region to a thicker sub-region, which can effectively meet the electrical conductivity of each part of the metal layer, improve the electrical conductivity of the pole piece 10, and improve the electrical conductivity of the active material layer and the metal layer. The bond between the layers is better.

The above descriptions are only a part of the embodiments of the present application, and are not intended to limit the present application. For those skilled in the art, the present application may have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of this application shall be included within the protection scope of this application.

Claims (15)

1. A bipolar current collector, comprising an insulating film layer, a positive electrode metal layer and a negative electrode metal layer;

   The insulating film layer has a first surface and a second surface oppositely arranged along the thickness direction, the positive metal layer is arranged on the first surface, and the negative metal layer is arranged on the second surface;

   The positive electrode metal layer has a first coating area for coating the positive electrode active material and a first tab area for connecting the positive electrode tab, and the thickness of the first tab area is larger than that of the first coating area the thickness of at least part of the area;

   The negative electrode metal layer has a second coating area for coating the negative electrode active material and a second tab area for connecting the negative electrode tab, and the thickness of the second tab area is greater than that of the second coating area thickness of at least part of the area.
2. The bipolar current collector of claim 1, wherein the first coating region includes a first sub-region and a second sub-region, the first sub-region being located in a width direction of the second sub-region At least one side of the first sub-region, the thickness of the first sub-region is greater than the thickness of the second sub-region, the thickness of the first tab region is greater than the thickness of the second sub-region and not lower than the thickness of the first sub-region the thickness of the area;

   The second coating area includes a third sub-area and a fourth sub-area, the third sub-area is located on at least one side in the width direction of the fourth sub-area, and the thickness of the third sub-area is greater than that of the fourth sub-area. The thickness of the fourth sub-region, the thickness of the second tab region is greater than the thickness of the fourth sub-region and not lower than the thickness of the third sub-region.
3. The bipolar current collector according to claim 2, wherein the first sub-regions are two and are distributed on opposite sides in the width direction of the second sub-region, and two of the first sub-regions Distributed at positions close to the first tab area and positions away from the first tab area; the third sub-areas are two and are distributed on opposite sides in the width direction of the fourth sub-area , the two third sub-regions are distributed at positions close to the second tab region and positions far from the second tab region.
4. The bipolar current collector of claim 2, wherein the thickness of the first sub-region is the same as the thickness of the first tab region, and the thickness of the third sub-region is the same as the thickness of the second tab region The thickness of the area is the same.
5. The bipolar current collector according to claim 2, wherein the width of the first sub-region is 1-5 mm, and the width of the third sub-region is 1-5 mm.
6. The bipolar current collector according to claim 2, wherein a fifth sub-region is further provided between the first sub-region and the second sub-region, and the fifth sub-region is along the second sub-region The thickness gradually increases from the region to the first sub-region; a sixth sub-region is further arranged between the third sub-region and the fourth sub-region, and the sixth sub-region is along the fourth sub-region The direction to the third sub-region gradually thickens.
7. The bipolar current collector of claim 1, wherein the thickness of the first tab region is greater than the thickness of the first coating region, and the thickness of the second tab region is greater than the thickness of the second coating region The thickness of the overlay.
8. The bipolar current collector according to claim 1, wherein a maximum thickness difference between the first tab region and the first coating region is 1-400 nm, and the second tab region and the first tab region have a maximum thickness difference of 1-400 nm. The maximum thickness difference of the two coating areas is 1-600nm;

   Optionally, the maximum thickness difference between the first tab area and the first coating area is 100-300 nm, and the maximum thickness difference between the second tab area and the second coating area is 200-300 nm. 500nm.
9. The bipolar current collector according to claim 1, wherein the thickness of the first coating region is 20-1500 nm, the thickness of the first tab region is 30-2000 nm; the thickness of the second coating region The thickness of the second tab region is 30-2500nm, and the thickness of the second tab region is 50-3000nm.
10. The bipolar current collector according to any one of claims 1-9, wherein the first surface has a first blank area and a first metal area covered by the positive metal layer, and the second surface has a first blank area and a first metal area covered by the positive metal layer. having a second blank area and a second metal area covered by the negative electrode metal layer;

    Wherein, in the thickness direction of the insulating film layer, at least part of the first tab area is disposed opposite to the second blank area, and at least part of the second tab area is opposite to the first blank area Relative settings.
11. 11. The bipolar current collector of claim 10, wherein the projection of the first tab area on the reference plane is located within the projection of the second blank area on the reference plane, the second tab area The projection of the reference plane is located within the projection of the first blank area on the reference plane, and the reference plane is perpendicular to the thickness direction of the insulating film layer.
12. 12. The bipolar current collector of claim 11, wherein the projection of the first tab region on the reference plane is spaced apart from the projection of the negative metal layer on the reference plane, the second tab region The projection on the reference plane is spaced apart from the projection of the positive metal layer on the reference plane.
13. The bipolar current collector according to claim 10, wherein, along the width direction of the insulating film layer, the first blank area and the second blank area are respectively close to two edges of the insulating film layer.
14. A pole piece comprising:

    The bipolar current collector of any one of claims 1-13;

    a positive electrode active material layer, the positive electrode active material layer is disposed in the first coating area;

    a negative electrode active material layer, the negative electrode active material layer is disposed in the second coating area;

    a positive electrode tab, the positive electrode tab is connected to the first tab area;

    A negative electrode tab, the negative electrode tab is connected to the second tab area.
15. A secondary battery, comprising an electric core, the electric core comprising a plurality of pole pieces according to claim 14, and a plurality of separators, one of the separators is arranged between two adjacent pole pieces, And the positive electrode active material layer and the negative electrode active material layer are respectively provided on both sides of the separator.

Images