CN206098526U - Coiling formula secondary electricity core - Google Patents

Abstract

The utility model provides a coiling formula secondary electricity core, it includes anode pole piece, cathode and barrier film, on the width direction of secondary electricity core, anode pole piece's coiling starting layer and cathode's coiling starting layer extend towards same direction, and anode pole piece's coiling initiating terminal surpasss cathode's coiling initiating terminal, coated respectively first anode active material layer and first negative pole active material layer of relative one side each other among anode pole piece's coiling starting layer and cathode's the coiling starting layer to first anode active material layer's initiating terminal surpasss first negative pole active material layer's initiating terminal, along anode pole piece's coiling starting layer's extending direction, anode pole piece's coiling initiating terminal is equipped with the blank positive pole mass flow body in the position department that misses the first anode active material layer initiating terminal, and positive pole utmost point ear is fixed on the blank positive pole mass flow body. Compared with the prior art, the utility model discloses coiling formula secondary electricity core has the energy density height, has advantages such as analysing the lithium risk.

Description

Winding secondary battery

technical field

The utility model belongs to the field of secondary batteries, in particular to a winding secondary battery core.

Background technique

Lithium-ion secondary batteries are widely used in various electronic products. In conventional wound secondary batteries, blank current collectors are provided at the starting ends of the cathode pole piece and the anode pole piece, and the cathode tab and the anode tab are directly welded to the blank current collectors on the cathode pole piece and the anode pole piece respectively. superior. However, due to the accumulation of the thickness of the tabs, the thickness of the welded tab area is the maximum thickness of the cell, while the thickness of the unwelded tab area is relatively small, and the uneven thickness makes part of the space of the battery cannot be fully utilized, resulting in Within a certain model size, it is difficult to further increase the energy density of the battery.

In order to solve the above problems, the battery cells of some secondary batteries fix the tabs in the following way: set tab grooves exposing blank current collectors in the active material layer of the pole piece, and fix the tabs in the tab grooves, In order to achieve the purpose of increasing the energy density. However, if all the lugs of the cathode and anode pieces are placed in the lug grooves, the lithium extracted from the cathode piece corresponding to the lug groove of the anode piece will be received by the anode piece, causing the cell to There is a risk of lithium analysis.

In view of this, it is indeed necessary to provide a secondary battery cell capable of solving the above technical problems.

Utility model content

The purpose of the utility model is to provide a winding secondary battery cell with no risk of lithium analysis and high energy density.

In order to achieve the above purpose, the utility model provides a winding secondary cell, including an anode pole piece, a cathode pole piece and a separator, and the separator is spaced between adjacent cathode pole pieces and anode pole pieces;

The anode sheet includes an anode current collector, an anode active material layer coated on at least one surface of the anode current collector, and an anode tab electrically connected to the anode current collector;

The cathode sheet includes a cathode current collector, a cathode active material layer coated on at least one surface of the cathode current collector, and a cathode tab electrically connected to the cathode current collector;

In the width direction of the secondary battery, the winding start layer of the anode pole piece and the winding start layer of the cathode pole piece extend in the same direction, and the length of the winding start layer of the anode pole piece is longer than that of the cathode pole piece. Around the length of the starting layer, so that the winding starting end of the anode pole piece exceeds the winding starting end of the cathode pole piece; the opposite sides of the winding starting layer of the anode pole piece and the winding starting layer of the cathode pole piece are respectively Coated with the first anode active material layer and the first cathode active material layer, and the starting end of the first anode active material layer exceeds the starting end of the first cathode active material layer; In the extension direction, a blank anode current collector is provided at the position where the winding starting end of the anode pole piece does not reach the starting end of the first anode active material layer, and the anode tab is fixed on the blank anode current collector.

As an improvement of the winding-type secondary cell of the present invention, in the thickness direction of the secondary cell, the winding-starting layer of the cathode pole piece is located outside the winding-starting layer of the anode pole piece.

As an improvement of the wound secondary battery of the present invention, both sides of the winding start end of the cathode pole piece are coated with the first cathode active material layer and no blank cathode current collector is provided.

As an improvement of the winding-type secondary cell of the present invention, the cathode tab is a blank cathode current collector directly reserved on the edge of the cathode sheet in the width direction.

As an improvement of the winding type secondary cell of the present invention, the first cathode active material layer of the cathode pole piece is provided with a cathode lug groove exposing a blank cathode current collector, and the cathode lug is fixed on the cathode electrode in the ear groove.

As an improvement of the winding type secondary cell of the present invention, the cathode lug groove is a short groove that is closed on three sides and opened on one side that does not penetrate through the width direction of the cathode pole piece.

As an improvement of the winding secondary battery cell of the utility model, the anode lug is welded on the blank anode current collector.

Compared with the prior art, the winding secondary battery core of the utility model has the advantages of high energy density and no risk of lithium analysis.

Description of drawings

The winding secondary cell of the present invention and its beneficial technical effects will be described in detail below in conjunction with the accompanying drawings and specific implementation methods.

FIG. 1 is a schematic structural view of the first embodiment of the wound secondary battery of the present invention.

FIG. 2 is a schematic diagram of the lug connection structure of the anode pole piece and the cathode pole piece in FIG. 1 .

Fig. 3 is a schematic structural view of the second embodiment of the wound secondary battery of the present invention.

FIG. 4 is a schematic diagram of the lug connection structure of the anode pole piece and the cathode pole piece in FIG. 3 .

detailed description

In order to make the purpose, technical solution and beneficial technical effects of the utility model clearer, the utility model will be further described in detail below in conjunction with the accompanying drawings and specific implementation methods. It should be understood that the specific implementations described in this specification are only for explaining the utility model, not for limiting the utility model.

For the convenience of description, the utility model defines the shorter side of the cathode pole piece and the anode pole piece as the pole piece width direction L1, and the pole piece extending direction perpendicular to it is defined as the pole piece length direction L2. It is easy to understand that since the winding of the cathode electrode piece and the anode electrode piece is carried out along the length direction L2, in the final wound cell, the width direction L1 of the cathode electrode sheet corresponds to the cell length direction ( The direction perpendicular to the paper surface in FIG. 1 ), that is to say, the pole piece width direction L1 is not the same as the cell width direction L, but are perpendicular to each other. Similarly, the length direction L2 of the cathode and anode pieces corresponds to the width direction L of the cell.

Please refer to FIG. 1 to FIG. 4 , the first and second implementations of the wound secondary cell of the present invention both include an anode pole piece 10 , a cathode pole piece 20 and a separator 30 . The anode sheet 10 includes an anode current collector 11 , an anode active material layer 12 coated on at least one surface of the anode current collector 11 , and an anode tab 13 electrically connected to the anode current collector 11 . The cathode sheet 20 includes a cathode current collector 21 , a cathode active material layer 22 coated on at least one surface of the cathode current collector 21 , and a cathode tab 23 electrically connected to the cathode current collector 21 . The anode pole piece 10 , the separator 30 and the cathode pole piece 20 are laminated and then wound into a winding cell, and the separator 30 is spaced between adjacent anode pole pieces 10 and cathode pole pieces 20 .

In the thickness T direction of the secondary cell, the winding start layer 25 of the cathode electrode piece 20 is located outside the winding start layer 15 of the anode electrode piece 10 . On the width direction L of the secondary battery, the winding initiation layer 15 of the anode pole piece 10 and the winding initiation layer 25 of the cathode pole piece 20 extend toward the same direction (with the winding starting end as the starting point, the pole piece roll The direction of time around is its extension direction). The length of the winding start layer 15 of the anode pole piece 10 is greater than the length of the winding start layer 25 of the cathode pole piece 20, so that the winding start end 150 of the anode pole piece 10 exceeds the winding start end 250 of the cathode pole piece 20 . The opposite sides of the winding starting layer 15 of the anode pole piece 10 and the winding starting layer 25 of the cathode pole piece 20 are respectively coated with the first anode active material layer 120 and the first cathode active material layer 220, and the second The starting end of an anode active material layer 120 is beyond the starting end of the first cathode active material layer 220 . Along the extension direction of the winding starting layer 15 of the anode pole piece 10, the winding starting end 150 of the anode pole piece 10 is provided with a blank anode current collector 110 at a position that does not reach the starting end of the first anode active material layer 120, The anode tab 13 is fixed on the blank anode current collector 110 by welding to realize electrical connection with the anode sheet 10 .

Both sides of the winding starting end 250 of the cathode sheet 20 are coated with the first cathode active material layer 220 , and no blank cathode current collector is provided.

The difference between the first and second embodiments of the wound-type secondary battery of the present invention lies in the arrangement of the cathode tab 23 , which will be described in detail below.

In the first embodiment shown in FIGS. 1 and 2 , the first cathode active material layer 220 of the cathode sheet 20 is provided with a cathode lug groove 222 exposing a blank cathode current collector, and the cathode lug 23 is fixed on the cathode electrode. In the lug groove 222 . The cathode tab groove 222 is a short groove slightly larger than the fixed end of the cathode tab 23 , which does not penetrate the width direction L2 of the cathode tab 20 , so three sides are closed and one side is open. There are many ways to form short grooves, one of which is to paste easy-tear film or thermal expansion film on the fixed position of the tab of the blank cathode current collector, and then continuously coat the cathode active material layer, and finally remove the easy-tear film or thermal expansion film. Short grooves are formed by thermally expanding the film.

In the second embodiment shown in FIGS. 3 and 4 , the cathode pole piece 20 adopts a multi-tab design, that is, a plurality of uncut blank cathode current collectors are reserved on the widthwise edge of the cathode pole piece 20 as cathode tabs. twenty three. Since the cathode tab 23 is a blank cathode current collector integrated with the cathode sheet 20, there is no need to provide a groove for the cathode tab as a connection point.

Compared with the prior art, the utility model winding secondary battery has at least the following advantages:

1) The anode tab 13 is fixed on the blank anode current collector 110 at the position of the winding start end 150 of the anode pole piece 10, and the winding start end 150 of the anode pole piece 10 exceeds the winding start end 250 of the cathode pole piece 20, Therefore, the anode tab 13 does not directly correspond to the cathode tab 20, which ensures that the existence of the anode tab 13 will not lead to an increase in the thickness of the secondary battery, and avoids the cathode at the corresponding position of the anode tab 13. Electrode 20 appears to precipitate lithium;

2) The cathode tab 20 adopts a cathode tab groove 222 or a multi-tab structure with an opening on one side, which not only avoids the accumulation of the thickness of the cathode tab 23 and the anode tab 13, but also does not cause electric shock due to the existence of the cathode tab 23. The increased core thickness is beneficial to improve the energy density of the secondary battery.

According to the above principles, the utility model can also make appropriate changes and modifications to the above embodiments. Therefore, the utility model is not limited to the specific implementation manners disclosed and described above, and some modifications and changes to the utility model should also fall within the scope of protection of the claims of the utility model. In addition, although some specific terms are used in this specification, these terms are only for convenience of description and do not constitute any limitation to the present utility model.

Claims (7)

1. a kind of coiled secondary battery core, including anode pole piece, cathode sheet and isolating membrane, isolating membrane is interval in adjacent negative electrode Between pole piece and anode pole piece；

The anode pole piece includes anode collector, the anode active material layer being coated on the surface of anode collector at least one With the anode lug being connected electrically in anode collector；

The cathode sheet includes cathode current collector, the cathode active material layer being coated on the surface of cathode current collector at least one With the cathode tab being connected electrically on cathode current collector；

It is characterized in that：

On the width of secondary battery core, the winding initial layers of anode pole piece and the winding initial layers of cathode sheet are towards same side To extension, the winding initial layers length of anode pole piece is more than the winding initial layers length of cathode sheet so that the volume of anode pole piece Exceed the winding initiating terminal of cathode sheet around initiating terminal；In the winding initial layers of anode pole piece and the winding initial layers of cathode sheet One side relative to each other has been respectively coated with first anode active material layer and the first cathode active material layer, and the first anode is lived Property material layer initiating terminal beyond the first cathode active material layer initiating terminal；Along the extension of the winding initial layers of anode pole piece Direction, the winding initiating terminal of anode pole piece is provided with blank anode at the not up to position of first anode active material layer initiating terminal Collector, anode lug is fixed in blank anode collector.

2. coiled secondary battery core according to claim 1, it is characterised in that：On the thickness direction of secondary battery core, institute The winding initial layers for stating cathode sheet are located at the outside for winding initial layers of anode pole piece.

3. coiled secondary battery core according to claim 1, it is characterised in that：The winding initiating terminal of the cathode sheet Two sides is coated with the first cathode active material layer and does not set blank cathode current collector.

4. coiled secondary battery core according to claim 3, it is characterised in that：The cathode tab is directly in negative electrode pole The reserved blank cathode current collector of piece widthwise edges.

5. coiled secondary battery core according to claim 3, it is characterised in that：First cathode activity of the cathode sheet The cathode tab groove for exposing blank cathode current collector is provided with material layer, cathode tab is fixed in cathode tab groove.

6. coiled secondary battery core according to claim 5, it is characterised in that：The cathode tab groove is not for through the moon The three side sealing of pole pole piece width is closed, the short groove of one side opening.

7. coiled secondary battery core according to claim 1, it is characterised in that：The anode tab welding is in blank anode On collector.