Electrode assembly and battery cell

Abstract

The utility model relates to the technical field of battery manufacturing, and particularly provides an electrode assembly and a battery cell. The battery cell comprises a first surface located on an anode pole piece and a second surface deviating from the interior of the battery cell, wherein the second surface is arranged deviating from the first surface; a first active substance coating and a second active substance coating are respectively arranged on the first surface and the second surface; wherein the area, which is not coated with the first active material coating, in the corresponding area of the second active material coating on the first surface is a single-side coating area; the lithium ion battery is characterized in that the anode pole piece further comprises an edge coating covering the single-side coating area; according to the utility model, the edge coating is attached to the single-sided coating area to compensate the thickness difference between the single-sided coating area and the double-sided coating area, so that active substances in the junction of the single-sided coating area and the double-sided coating area and the empty foil area close to the coating areas are prevented from falling off, and the lithium precipitation phenomenon of the finished battery cell is further prevented.

Description

Technical Field

[0001] The utility model belongs to the technical field of energy storage devices, and more specifically, relates to an electrode assembly and a battery core. Background Art

[0002] The coil core is divided into a double-sided coating area and a single-sided coating area according to the different lengths of the coating layers on both sides of the anode pole piece, so that there is a thickness difference at the junction of the two areas (in the direction of the thickness of the battery cell). In the rolling process, due to the different thicknesses at the junction of the two areas, the single-sided coating area at the junction of the two areas has different degrees of insufficient compaction density (that is, rolling has a huge impact on the pore structure of the anode pole piece, and also affects the distribution of the conductive agent on the anode pole piece). Rolling will affect the particle spacing of the coating, thereby affecting the inter-particle adhesion, ion and electron conduction during the electrochemical reaction, etc., so that the active material at the junction of the two areas is easy to peel off during the cycle, which leads to a reduction in the number of lithium ions that can be received here, resulting in lithium precipitation, and also causing deformation of the battery cell.

[0003] Moreover, the anode head (innermost layer) of the wound battery cell is folded into a single-sided coating area. During the winding process, the force applied to the active material coating area and the empty foil area is inconsistent, so the empty foil area will be folded, causing the active material on the anode electrode to peel off, resulting in poor K value (K value refers to the voltage drop of the battery per unit time, which is a physical quantity used to describe the self-discharge rate of the battery cell), and abnormal phenomena such as lithium deposition during cycling.

[0004] Based on this, it is urgent to invent an electrode assembly and a battery cell to solve the above-mentioned technical problems. Utility Model Content

[0005] The technical problem to be solved by the utility model is how to avoid the peeling of active material at the junction of the single-sided coating area and the double-sided coating area of ​​the anode electrode and in the empty foil area close to the active material coating area. In view of the above problems, an electrode assembly and a battery cell are provided.

[0006] The technical solution of the utility model to solve the above technical problems is to provide an electrode assembly, including: a first surface located on the anode electrode sheet and a second surface facing away from the interior of the battery cell, and the second surface is arranged away from the first surface; a first active material coating is arranged on one of the first surface and the second surface, and a second active material coating is arranged on the other.

[0007] Wherein, the area on the first surface corresponding to the area of ​​the second active material coating that is not coated with the first active material coating is a single-sided coating area; characterized in that: the anode electrode sheet further includes:

[0008] Covering the edge coating on the single-sided coated area, and S = S O -S T ,W=W A ; Wherein, S is the length value of the edge coating; S O is the length of the second active material coating; S T is the length of the first active material coating; W is the width of the edge coating; W A is the width of the anode electrode.

[0009] Specifically, D=T*ρ, wherein D is the surface density of the edge coating; T is the thickness of the active material coating; and ρ is the density of the coating in the edge coating.

[0010] More specifically, the density value ρ of the coating in the edge coating is 1.18 kg / m 3 ~6.5kg / m 3 .

[0011] Preferably, one end of the edge coating layer is joined to an end of the first active material coating layer.

[0012] More preferably, along the thickness direction of the battery cell, the thickness of the anode electrode sheet at the edge coating is equal to the thickness of the anode electrode sheet at the overlapped portion of the first active material coating and the second active material coating.

[0013] More preferably, the edge coating is an oxide coating, and the oxide in the oxide coating includes one or more of aluminum oxide, zirconium oxide, magnesium oxide, quartz and titanium dioxide.

[0014] Preferably, an end of the first active substance coating layer facing away from the edge coating layer is flush with a corresponding end of the second active substance coating layer.

[0015] Preferably, the active material in the first active material coating is the same as the active material in the second active material coating.

[0016] In one specific embodiment, the area on the anode electrode sheet where the first active material coating and the second active material coating are not applied is a hollow foil area;

[0017] The electrode assembly further includes an anode tab, which is welded to the empty foil area on the first surface; or a groove for welding the anode tab is provided on the first active material coating.

[0018] In one specific embodiment, the utility model provides a battery cell, comprising an electrode assembly as described above.

[0019] The beneficial effect of the utility model is that the edge coating is applied to the single-sided coating area to compensate for the thickness difference between the single-sided coating area and the double-sided coating area, thereby preventing the active material in the junction of the single-sided coating area and the double-sided coating area and in the empty foil area close to the coating area from falling off, thereby preventing lithium deposition in the finished battery cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a cross-sectional view of an electrode assembly according to one embodiment of the present utility model;

[0021] Figure 2 It is a schematic structural diagram of an electrode assembly in one embodiment of the utility model in which the anode tab is located in one direction of the empty foil area;

[0022] Figure 3 It is a schematic structural diagram of an electrode assembly in which the anode tab is located in another direction of the empty foil area in one embodiment of the utility model;

[0023] Figure 4 It is a schematic structural diagram of one direction in which the anode tab of an electrode assembly in one embodiment of the utility model is located at the first active material coating;

[0024] Figure 5 It is a schematic structural diagram of another direction in which the anode tab of the electrode assembly in one embodiment of the utility model is located at the first active material coating.

[0025] Reference numerals:

[0026] 2-electrode assembly; 20-anode electrode; 200-first surface; 201-second surface;

[0027] 2000-first active material coating; 2001-edge coating; 2002-groove; 2003-single-side coating area; 2010-second active material coating; 21-anode ear; 22-empty foil area;

[0028] 23- cathode electrode; 24- isolating film. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solution and advantages of the utility model more clear, the utility model is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the utility model and are not used to limit the utility model.

[0030] Combination Figure 1 to Figure 5The utility model provides an electrode assembly 2, comprising a first pole piece, a second pole piece and a separator 24, wherein the polarity of the first pole piece is opposite to that of the second pole piece, and the separator 24 is disposed between the first pole piece and the second pole piece. Specifically, the electrode assembly 2 is wound by the first pole piece, the separator and the second pole piece. Obviously, one of the first pole piece and the second pole piece is an anode pole piece 20, and the other is a cathode pole piece 23. The electrode assembly 2 is divided into a single-side coating area 2003 and a double-side coating area according to the different coating length values ​​of the two sides of the anode pole piece 20, that is, the length value of the first active material coating 2000 is different from the length value of the second active material coating 2010, so that the anode pole piece 20 forms a thickness difference (in the thickness direction of the battery cell) at the junction of the single-side coating area 2003 and the double-side coating area, thereby causing the active material in the empty foil area 22 near the active material coating area (specifically the single-side coating area 2003) to peel off (that is, powder). Based on this, the technical solution of the utility model is improved.

[0031] The following are some specific implementations of the technical solution of the utility model. In the absence of conflict, the following implementations can be combined with each other, and the technical features of one implementation can also be combined with the technical features of other implementations.

[0032] Implementation Method 1

[0033] Continue to refer Figure 2 to Figure 5 , the electrode assembly 2 includes a first surface 200 located on the anode plate 20 and a second surface 201 away from the inside of the battery cell, and the second surface 201 is away from the inside of the battery cell, that is, the second surface 201 is arranged away from the first surface 200. Generally, the anode plate 20 uses a coating process to coat one or more layers of liquid on the substrate, and then the coated liquid coating (the liquid coating includes a conductive agent) is dried in an oven or cured to form a film layer with special functions (that is, an active material coating) on ​​the substrate, that is, the first surface 200 and the second surface 201 are respectively provided with a first active material coating 2000 and a second active material coating 2010. Among them, the area of ​​the first surface 200 corresponding to the second active material coating 2010 that is not coated with the first active material coating 2000 is a single-sided coating area 2003. In contrast, the area on the anode plate 20 coated with the first active material coating 2000 and the second active material coating 2010 is a double-sided coating area.

[0034] like Figure 3 to Figure 5 As shown, in order to compensate for the thickness difference at the junction of the single-side coating area 2003 and the double-side coating area, the anode plate 20 further includes an edge coating 2001 covering the single-side coating area 2003.O -S T ,W=W A ; Wherein, S is the length value of the edge coating 2001; S O is the length value of the second active material coating 2010; S T is the length of the first active material coating 2000; W is the width of the edge coating 2001; W A is the width value of the anode electrode sheet 20. Of course, in other specific embodiments, the length value of the edge coating 2001 can also be greater than the difference between the length value of the second active material coating 2010 and the length value of the first active material coating 2000, and the thickness difference at the junction of the single-sided coating area 2003 and the double-sided coating area can be compensated, thereby preventing the active material at the junction of the single-sided coating area 2003 and the double-sided coating area and the empty foil area 22 near the active material coating area from peeling off, thereby causing lithium deposition in the finished battery cell.

[0035] Implementation Method 2

[0036] The difference between this embodiment and embodiment 1 is that: in order to ensure that the thickness of the anode electrode sheet 20 at the edge coating 2001 is the same as the thickness of the anode electrode sheet 20 at the double-sided coating area through the coating surface density, D=T*ρ, where D is the surface density of the edge coating 2001; T is the thickness of the active material coating; ρ is the density of the coating in the edge coating 2001. The other parts of this embodiment are the same as those in embodiment 1 and are not described here.

[0037] Implementation 3

[0038] The difference between this embodiment and embodiment 2 is that the density value ρ of the coating in the edge coating is 1.18 kg / m 3 ~6.5kg / m 3 The other parts of this embodiment are the same as those of Embodiment 2 and will not be described in detail here.

[0039] Implementation 4

[0040] The difference between this embodiment and embodiment 1 is that, in order to improve the consistency of the thickness of the anode electrode sheet 20, one end of the edge coating 2001 is joined to the end of the first active material coating 2000. The other parts of this embodiment are the same as those of embodiment 1 and are not described here.

[0041] Implementation method 5

[0042] The difference between this embodiment and embodiment 1 is that, in order to further improve the consistency of the thickness of the anode electrode sheet 20, along the thickness direction of the battery cell, the thickness of the anode electrode sheet 20 at the edge coating 2001 is equal to the thickness of the anode electrode sheet 20 at the overlap of the first active material coating 2000 and the second active material coating 2010. The other parts of this embodiment are the same as those of embodiment 1 and are not described here.

[0043] Implementation 6

[0044] The difference between this embodiment and embodiment 1 is that in order to ensure the consistency of the single-sided and double-sided compaction density and the force of the anode electrode 20, the edge coating 2001 is an oxide coating, and the oxide in the oxide coating includes one or more of aluminum oxide, zirconium oxide, magnesium oxide, quartz and titanium dioxide. Of course, in other specific embodiments, the oxide in the oxide coating may also include other oxides. The other parts of this embodiment are the same as those in embodiment 1, and are not described here.

[0045] Implementation 7

[0046] The difference between this embodiment and embodiment 1 is that, in order to prevent the thickness difference between the single-sided coating area 2003 and the double-sided coating area of ​​the anode electrode sheet 20 from occurring again, the end of the first active material coating 2000 away from the edge coating 2001 is flush with the corresponding end of the second active material coating 2010. The other parts of this embodiment are the same as those of embodiment 1 and are not described in detail here.

[0047] Implementation 8

[0048] The difference between this embodiment and embodiment 1 is that the active material in the first active material coating 2000 is the same as the active material in the second active material coating 2010, so that the active material coated on both sides of the anode electrode in the same battery cell is the same. Of course, in other specific embodiments, the active material in the first active material coating 2000 and the active material in the second active material coating 2010 may also be different. The other parts of this embodiment are the same as embodiment 1 and are not described in detail here.

[0049] Implementation method 9

[0050] Continue to refer Figure 3 to Figure 5The difference between this embodiment and embodiment 1 is that the area on the anode electrode sheet 20 for covering the first active material coating 2000 and the second active material coating 2010 is a hollow foil area 22, and the electrode assembly 2 further includes an anode tab 21, which is welded on the hollow foil area 22 of the first surface 200; or a groove 2002 for welding the anode tab 21 is provided on the first active material coating 2000, so as to facilitate electrical connection to an external circuit through the anode tab 21. The other parts of this embodiment are the same as those in embodiment 1, and are not described in detail here.

[0051] Embodiment 10

[0052] The difference between this embodiment and the above embodiments is that this embodiment provides a battery cell, including the electrode assembly 2 in the above embodiments. The other parts of this embodiment are the same as any of the above embodiments, and will not be described in detail here.

[0053] The above is only a preferred specific implementation of the utility model, but the protection scope of the utility model is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the utility model should be included in the protection scope of the utility model. Therefore, the protection scope of the utility model should be based on the protection scope of the claims.

Claims

1. An electrode assembly, comprising a first surface located on an anode electrode sheet and a second surface facing away from the interior of a battery cell, wherein the second surface is arranged away from the first surface; a first active material coating is arranged on one of the first surface and a second active material coating is arranged on the other; in, The area on the first surface that is not coated with the first active material coating in the area corresponding to the second active material coating is a single-sided coating area; characterized in that: the anode electrode sheet further includes: Covering the edge coating on the single-sided coated area, and S = S O -S T , W=W A ; Wherein, S is the length value of the edge coating; S O is the length of the second active material coating; S T is the length of the first active material coating; W is the width of the edge coating; W A is the width of the anode electrode.

2. The electrode assembly according to claim 1, characterized in that: D=T*ρ, wherein D is the surface density value of the edge coating; T is the thickness value of the active material coating; and ρ is the density value of the coating in the edge coating.

3. The electrode assembly according to claim 2, characterized in that: The density value ρ of the coating in the edge coating is 1.18 kg / m 3 ~6.5 kg / m 3 .

4. The electrode assembly according to claim 1, characterized in that: One end of the edge coating layer is joined to an end of the first active material coating layer.

5. The electrode assembly according to claim 1, characterized in that: Along the thickness direction of the battery cell, the thickness of the anode electrode sheet at the edge coating is equal to the thickness of the anode electrode sheet at the overlapped portion of the first active material coating and the second active material coating.

6. The electrode assembly according to claim 1, characterized in that: The edge coating is an oxide coating, and the oxide in the oxide coating is one of aluminum oxide, zirconium oxide, magnesium oxide, quartz or titanium dioxide.

7. The electrode assembly according to claim 1, characterized in that: An end of the first active substance coating layer facing away from the edge coating layer is flush with a corresponding end of the second active substance coating layer.

8. The electrode assembly according to claim 1, characterized in that: The active material in the first active material coating layer is the same as the active material in the second active material coating layer.

9. The electrode assembly according to any one of claims 1 to 8, characterized in that: The area on the anode electrode sheet where the first active material coating and the second active material coating are not applied is a blank foil area; The electrode assembly further includes an anode tab, which is welded to the empty foil area on the first surface; or a groove for welding the anode tab is provided on the first active material coating.

10. A battery cell, characterized in that: Comprising the electrode assembly as claimed in claim 9.

Images