Pole piece and electrochemical device

Abstract

The utility model relates to battery technology field discloses a kind of pole piece and electrochemical device, pole piece includes current collector and active coating, current collector has the first side and the second side of opposite setting along its thickness direction, and active coating is all set on the first side and the second side. Multiple grooves and multiple through holes are set on the current collector with interval, and the through hole is communicated the first side and the second side. The utility model sets through hole and groove simultaneously on the current collector, improves the adhesion ability of current collector and active material, provides enough space for electrolyte storage, meets the ion migration needs simultaneously, replaces part of through hole by groove, reduces the number of through hole, to avoid that current collector strength reduces too much.

Description

Technical Field

[0001] This utility model relates to the field of battery technology, and in particular to an electrode and an electrochemical device. Background Technology

[0002] The current collector in the electrode plays a crucial role in carrying the active material and conducting electricity in the battery. The contact effect between the active material and the current collector directly affects the battery's performance. Drilling holes in the current collector can improve the adhesion between the current collector and the active material. Furthermore, the drilled current collector provides a wetting channel for the lithium-ion battery electrolyte, improving wetting issues at cell corners. It also provides a migration channel for ions, mitigating lithium plating problems in some areas caused by insufficient electrolyte retention, hindered wetting, and impeded ion migration. However, the presence of holes in the current collector can reduce its strength; too many holes can lead to an excessive decrease in current collector strength.

[0003] Therefore, there is an urgent need for an electrode and an electrochemical device to solve the above problems. Utility Model Content

[0004] The purpose of this application is to provide an electrode and an electrochemical device that improves the bonding ability between the current collector and the active material, provides sufficient space for electrolyte storage, meets the needs of ion migration, and avoids excessive reduction in the strength of the current collector.

[0005] To achieve the above objectives, this application proposes an electrode sheet comprising a current collector and an active coating, wherein the current collector has a first side and a second side disposed opposite to each other along its own thickness direction, and the active coating is disposed on both the first side and the second side.

[0006] The current collector is provided with a plurality of grooves and a plurality of through holes at intervals, and the through holes connect the first side and the second side.

[0007] In some embodiments, the diameter of the groove gradually decreases from the top to the bottom of the groove.

[0008] In some embodiments, the groove diameter at the maximum groove diameter is 15um-500um.

[0009] In some embodiments, the aperture of the through hole is 10um-200um.

[0010] In some embodiments, the through holes and the grooves form a hole-groove array, which includes multiple rows of holes and grooves spaced apart along the length direction of the current collector. Each row of holes and grooves includes multiple through holes and multiple grooves, and the through holes and grooves in the same row of holes and grooves are spaced apart along the width direction of the current collector.

[0011] In some embodiments, the through holes and the grooves are alternately arranged within the same row of holes and slots.

[0012] In some embodiments, within the same row of holes and slots, the distance between the through hole and the adjacent groove is 0.2mm-10mm, and the distance between two adjacent rows of holes and slots along the length of the current collector is 0.2mm-10mm.

[0013] In another aspect, this application proposes an electrochemical device, including a battery cell body and a lithium source. The battery cell body includes a separator and an electrode as described in any of the above claims. The separator is sandwiched between two adjacent electrodes, and the lithium source is disposed within the battery cell body.

[0014] In some embodiments, the main body of the battery cell is a wound battery cell, the main body of the battery cell having a square portion and two arc-shaped portions, the two arc-shaped portions being located at both ends of the width direction of the square portion, and the lithium source being disposed in both arc-shaped portions and / or the lithium source being disposed at the center of the thickness direction of the square portion.

[0015] In some embodiments, the cell body is a laminated cell, and the lithium source is disposed at the middle part and / or both ends of the cell body in the thickness direction.

[0016] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0017] The electrode of this invention features through-holes and grooves on its current collector. Both the through-holes and grooves enhance the adhesion between the current collector and the active material, and provide space for electrolyte storage. This solves the problem of insufficient electrolyte, hindering ion migration and causing lithium plating, due to reduced electrolyte storage space caused by cell cyclic expansion. Furthermore, the through-holes also provide wetting channels for the electrolyte and migration channels for ions. By simultaneously incorporating through-holes and grooves on the current collector, this invention improves the adhesion between the current collector and the active material, provides sufficient space for electrolyte storage to meet ion migration requirements, and reduces the number of through-holes by replacing some with grooves, thereby preventing excessive reduction in current collector strength. Attached Figure Description

[0018] Figure 1 This is a top view of the electrode sheet provided in Embodiment 1 of this utility model;

[0019] Figure 2 This is a top view of the current collector of the electrode provided in Embodiment 1 of this utility model;

[0020] Figure 3 This is a top view of the current collector of the electrode provided in Embodiment 2 of this utility model;

[0021] Figure 4 This is a schematic diagram of the electrochemical device provided in Embodiment 3 of this utility model;

[0022] Figure 5 This is a schematic diagram of the electrochemical device provided in Embodiment 4 of this utility model;

[0023] Figure 6 This is a schematic diagram of the electrochemical device provided in Embodiment 5 of this utility model;

[0024] Figure 7 This is a schematic diagram of the electrochemical device provided in Embodiment Six of this utility model;

[0025] Figure 8 This is a schematic diagram of the electrochemical device provided in Embodiment 7 of this utility model.

[0026] In the picture:

[0027] 1. Current collector; 11. Through hole; 12. Groove;

[0028] 2. Active coating;

[0029] 10. Battery cell body; 101. Separator; 102. Square section; 103. Arc-shaped section;

[0030] 20. Lithium source. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. The embodiments of this application may omit unnecessary detailed descriptions. For example, detailed descriptions of well-known matters and repeated descriptions of actually identical structures may be omitted. This is to avoid making the following description unnecessarily lengthy and to facilitate understanding by those skilled in the art.

[0032] In this application, the technical features described in an open-ended manner include both closed technical solutions consisting of the listed features and open technical solutions that include the listed features.

[0033] As used herein, the terms “approximately,” “generally,” “substantially,” and “about” are used to describe and indicate small variations. When used in conjunction with an event or situation, the terms may refer to examples in which the event or situation occurred precisely and examples in which the event or situation occurred very approximately. For example, when used in conjunction with numerical values, the terms may refer to a range of variation less than or equal to ±10% of the numerical value, such as less than or equal to ±5%, less than or equal to ±4%, less than or equal to ±3%, less than or equal to ±2%, less than or equal to ±1%, less than or equal to ±0.5%, less than or equal to ±0.1%, or less than or equal to ±0.05%. For example, if the difference between two values ​​is less than or equal to ±10% of the average of the values ​​(e.g., less than or equal to ±5%, less than or equal to ±4%, less than or equal to ±3%, less than or equal to ±2%, less than or equal to ±1%, less than or equal to ±0.5%, less than or equal to ±0.1%, or less than or equal to ±0.05%), then the two values ​​can be considered "substantially" the same.

[0034] Furthermore, for ease of description, "first," "second," "third," etc., can be used in this article to distinguish different components of a figure or a series of figures. "First," "second," "third," etc., are not intended to describe the corresponding components.

[0035] Additionally, quantities, ratios, and other numerical values ​​are sometimes presented in range format in this document. It should be understood that such range format is for convenience and brevity and should be interpreted flexibly to include not only the numerical values ​​explicitly specified as range limits, but also all individual numerical values ​​or subranges covered within the range, as if each numerical value and subrange were explicitly specified.

[0036] In the detailed description and claims, a list of items connected by the terms "one of," "among," "a kind of," or other similar terms may mean any of the listed items. For example, if items A and B are listed, then the phrase "one of A and B" means only A or only B. In another example, if items A, B, and C are listed, then the phrase "one of A, B, and C" means only A; only B; or only C. Item A may contain a single element or multiple elements. Item B may contain a single element or multiple elements. Item C may contain a single element or multiple elements.

[0037] In the detailed description and claims, the list of items connected by the term "at least one of" can mean any combination of the listed items. For example, if items A and B are listed, then the phrase "at least one of A and B" means only A; only B; or A and B. In another example, if items A, B, and C are listed, then the phrase "at least one of A, B, and C" means only A; or only B; only C; A and B (excluding C); A and C (excluding B); B and C (excluding A); or all of A, B, and C.

[0038] In the following description, all figures disclosed in this application are approximate values, regardless of whether the terms "about" or "approximately" are used in conjunction. They may vary by 1%, 2%, 5%, or sometimes 10% to 20%. Whenever a range of values ​​with a lower limit (RL) and an upper limit (RU) is disclosed, any values ​​falling within that range are specifically disclosed. Specifically, the following values ​​within this range are specifically disclosed: R = RL + k * (RU - RL), where k is a variable with a 1% increment from 1% to 100%, that is, k is 1%, 2%, 3%, 4%, 5%, ..., 50%, 51%, 52%, ..., 95%, 96%, 97%, 98%, 99%, or 100%. Furthermore, any range of values ​​defined by the two R values ​​as defined above are also specifically disclosed.

[0039] Example 1

[0040] like Figure 1 and Figure 2 As shown, this embodiment provides an electrode sheet, including a current collector 1 and an active coating 2. The current collector 1 has a first side and a second side disposed opposite to each other along its own thickness direction, and the active coating 2 is disposed on both the first side and the second side. The current collector 1 is provided with a plurality of grooves 12 and a plurality of through holes 11 at intervals, and the through holes 11 connect the first side and the second side.

[0041] The electrode provided in this embodiment has through holes 11 and grooves 12 on the current collector 1. Both the through holes 11 and the grooves 12 can improve the adhesion between the current collector 1 and the active material, and provide space for electrolyte storage. This solves the problem of insufficient electrolyte leading to lithium plating in the battery cell due to insufficient electrolyte storage space caused by the cyclic expansion of the battery cell, which hinders ion migration. In addition, the through holes 11 can also provide wetting channels for the electrolyte and migration channels for ions. In this embodiment, by simultaneously providing through holes 11 and grooves 12 on the current collector 1, the adhesion between the current collector 1 and the active material is improved, and sufficient space is provided for electrolyte storage to meet the needs of ion migration. At the same time, by replacing part of the through holes 11 with grooves 12, the number of through holes 11 is reduced, thereby avoiding excessive reduction in the strength of the current collector 1.

[0042] Optionally, the diameter of the groove 12 gradually decreases from the top to the bottom. For small-sized grooves 12, if a groove 12 with a constant cross-section is used, there is a problem that the groove 12 is difficult to process. In this embodiment, a groove 12 with a variable cross-section is used, where the diameter of the groove 12 gradually decreases from the top to the bottom. This type of groove 12 can be formed by laser processing. In this embodiment, the cross-section of the groove 12 that is coplanar with its own axis is U-shaped.

[0043] Furthermore, each groove 12 is disposed on the same side of the current collector 1 to facilitate uniform processing of the grooves 12. In this example, after the active coating 2 is applied to one side of the current collector 1, the grooves 12 are then processed on the other side of the current collector 1.

[0044] Furthermore, the diameter of the groove 12 at its maximum diameter is 15µm-500µm, meaning it can be 15µm, 250µm, or 500µm, etc. If the groove diameter of the groove 12 is too large, it will lead to an excessive reduction in the strength of the current collector 1, while if the groove diameter of the groove 12 is too small, it will hinder the entry of the electrolyte. In this embodiment, the groove diameter at its maximum diameter is 15µm-500µm, ensuring that the electrolyte can enter smoothly while avoiding excessive reduction in the strength of the current collector 1. In this embodiment, the ratio of the groove diameter at its maximum diameter to the depth of the groove 12 is not less than 1.5. If the ratio of the groove diameter to the depth is too small, it will hinder the entry of the electrolyte into the lower part of the groove 12.

[0045] Furthermore, the through-hole 11 is a hole of uniform diameter, with a diameter of 10µm-200µm, meaning the diameter can be 10µm, 100µm, or 200µm, etc. If the diameter of the through-hole 11 is too large, it will lead to an excessive reduction in the strength of the current collector 1; if the diameter is too small, it will hinder the passage of electrolyte. In this embodiment, the diameter of the through-hole 11 is 10µm-200µm, ensuring smooth passage of electrolyte while avoiding excessive reduction in the strength of the current collector 1. Compared to the groove 12, the through-hole 11 has a greater impact on the strength of the current collector 1; therefore, the diameter of the through-hole 11 is slightly smaller than the groove diameter at its maximum. In this embodiment, the through-hole 11 is processed after the active coating on both sides of the current collector 1 is applied. The through-hole 11 is formed by laser processing.

[0046] Optionally, the through holes 11 and the grooves 12 form a hole-groove array, which includes multiple rows of holes and grooves spaced apart along the length of the current collector 1. Each row of holes and grooves includes multiple through holes 11 and multiple grooves 12. The through holes 11 and grooves 12 in the same row of holes and grooves are spaced apart along the width of the current collector 1 so that the through holes 11 and grooves 12 are distributed throughout the entire current collector 1.

[0047] Furthermore, within the same row of holes and grooves, through holes 11 and grooves 12 are alternately arranged along the width direction of the current collector 1 to avoid the through holes 11 being too concentrated, which would result in the local strength of the current collector 1 being too low.

[0048] Furthermore, within the same row of holes / grooves, the distance between the through-hole 11 and the adjacent groove 12 is 0.2mm-10mm, and the distance between two adjacent rows of holes / grooves along the length of the current collector 1 is 0.2mm-10mm. Maintaining an appropriate distance between the through-hole 11 and the groove 12 ensures the strength of the current collector 1 while effectively improving the adhesion between the current collector 1 and the active material, providing sufficient space for electrolyte storage and meeting the needs of ion migration. In this embodiment, the distance between the through-hole 11 and the groove 12 refers to the distance between the edge of the through-hole 11 and the edge of the groove 12, and the distance of the rows of holes / grooves along the length of the current collector 1 refers to the distance between the edges of the rows of holes / grooves along the length of the current collector 1.

[0049] Furthermore, in this embodiment, in two adjacent slot rows, the through holes 11 of one slot row correspond one-to-one with the grooves 12 of the other slot row. Simultaneously, the grooves 12 of one slot row correspond one-to-one with the through holes 11 of the other slot row. The corresponding through holes 11 and grooves 12 on the current collector 1 form slot rows along the length of the current collector 1, and each slot row is spaced apart along the width of the current collector 1. Those skilled in the art will understand that the number of slot rows on the current collector 1 corresponds to the total number of through holes 11 and grooves 12 in a slot row. For example, if a slot row has a total of 3 through holes 11 and 2 grooves 12, then the current collector 1 has 5 slot rows. Within the same slot row, the axis of each through hole 11 is coplanar with the axis of each groove 12; within the same slot row, the axis of each through hole 11 is coplanar with the axis of each groove 12.

[0050] Example 2

[0051] like Figure 3 As shown, this embodiment provides an electrode sheet. The electrode sheet provided in this embodiment is basically the same as the electrode sheet in Embodiment 1. The difference is that in the current collector 1 in this embodiment, the axis of each through hole 11 is coplanar with the axis of each groove 12 in the same row of holes and grooves, and the axis of each through hole 11 is not coplanar with the axis of each groove 12 in the same row of holes and grooves.

[0052] Example 3

[0053] like Figure 4As shown, this embodiment provides an electrochemical device, including any device in which an electrochemical reaction occurs to interconvert chemical energy and electrical energy. Specific, non-limiting examples include all types of primary batteries, secondary batteries, fuel cells, solar cells, or capacitors. In particular, the electrochemical device is a lithium secondary battery, including lithium metal secondary batteries, lithium-ion secondary batteries, lithium polymer secondary batteries, or lithium-ion polymer secondary batteries.

[0054] The electrochemical device in this embodiment includes a battery cell body 10, which includes the electrode sheets from any of the embodiments in Example 1, Example 2, and Example 3, and also includes a separator 101 sandwiched between two adjacent electrode sheets. The electrochemical device provided in this embodiment improves the adhesion between the current collector 1 and the active material by simultaneously providing through holes 11 and grooves 12 on the current collector 1, providing sufficient space for electrolyte storage and meeting the needs of ion migration. At the same time, the grooves 12 replace some of the through holes 11, reducing the number of through holes 11 and thus preventing excessive reduction in the strength of the current collector 1.

[0055] In existing lithium batteries, lithium ions are gradually consumed during cell activation and subsequent cycling, resulting in a smaller amount of lithium ions that can be effectively used by the cell, leading to a decrease in the cell's effective capacity and reduced cell cycle performance.

[0056] To address the aforementioned issues, the electrochemical device provided in this embodiment further includes a lithium source 20, which is disposed within the cell body 10. By placing the lithium source 20 within the cell body 10, the lithium ions consumed during cell activation and subsequent cycling are replenished, thereby slowing down cell capacity decay, extending cell lifespan, and improving cell cycle performance.

[0057] In this embodiment, the lithium source 20 is a thin sheet to reduce the impact of its presence on the electrode and separator 101. The lithium source 20 can be a metallic lithium sheet or other metallic lithium carriers.

[0058] Furthermore, the cell body 10 is a wound cell, with two electrodes and a separator 101 wound together to form the cell body 10, which has a square portion 102 and two arc-shaped portions 103. The two arc-shaped portions 103 are located at both ends of the width direction of the wound cell, and a lithium source 20 is disposed at the center of the square portion 102 in the thickness direction. The center of the square portion 102 in the thickness direction is the central region of the cell body 10, and the lithium source 20 disposed there can replenish lithium ions to various regions of the cell body 10.

[0059] Example 4

[0060] like Figure 5As shown, this embodiment provides an electrochemical device, which is basically the same as the electrochemical device in Embodiment 3. The difference is that in this embodiment, the center of the square portion 102 in the thickness direction is not provided with a lithium source 20, but both arc-shaped portions 103 are provided with lithium sources 20. The two arc-shaped portions 103 of the battery cell body 10 are the parts of the battery cell body 10 most prone to lithium deficiency. In this embodiment, lithium sources are provided at these two locations in the battery cell body 10, which can directly replenish lithium in the two arc-shaped portions 103.

[0061] Example 5

[0062] like Figure 6 As shown, this embodiment provides an electrochemical device. The electrochemical device provided in this embodiment is basically the same as the electrochemical device in Embodiment 3, except that, in this embodiment, in addition to having a lithium source 20 disposed at the center of the square portion 102 of the battery cell body 10 in the thickness direction, a lithium source 20 is also disposed within the two arc-shaped portions 103. This facilitates lithium replenishment to various regions of the battery cell body 10, and provides focused lithium replenishment to the two arc-shaped portions 103.

[0063] Example 6

[0064] like Figure 7 As shown, this embodiment provides an electrochemical device, including a battery cell body 10. The battery cell body 10 includes the electrode sheets from any of the embodiments in Embodiment 1, Embodiment 2, and Embodiment 3, and also includes a separator 101 sandwiched between two adjacent electrode sheets. In this embodiment, the battery cell body 10 is a stacked battery cell, and a lithium source 20 is disposed at the center of the battery cell body 10 in the thickness direction. The center of the battery cell body 10 in the thickness direction is the central region of the battery cell body 10, and the lithium source 20 disposed therein can replenish lithium ions to various regions of the battery cell body 10.

[0065] Example 7

[0066] like Figure 8 As shown, this embodiment provides an electrochemical device, which is basically the same as the electrochemical device in Embodiment Six. The difference is that in this embodiment, the lithium source 20 is not provided in the middle of the thickness direction of the cell body 10, but lithium sources 20 are provided at both ends of the thickness direction of the cell body 10. The two ends of the thickness direction of the cell body 10 are the areas of the cell body 10 most prone to lithium deficiency. By providing lithium sources at these two locations, the cell body 10 in this embodiment can directly replenish lithium at both ends of the cell body 10.

[0067] Example 8

[0068] This embodiment provides an electrochemical device, which is basically the same as the electrochemical device in Embodiment Six. The difference is that, in this embodiment, in addition to the lithium source 20 being disposed in the middle of the thickness direction of the battery cell body 10, lithium sources 20 are also disposed at both ends of the thickness direction of the battery cell body 10. This is to facilitate lithium replenishment to various regions of the battery cell body 10, and to focus on lithium replenishment at both ends of the battery cell body 10.

[0069] Throughout this specification, references to "implementation," "partial implementation," "one implementation," "another implementation," "specific method," or "partial method" mean that at least one implementation or embodiment in this application includes the specific features, structures, materials, or characteristics described in that implementation or embodiment.

[0070] In this application, numerical ranges are involved. Unless otherwise specified, the numerical ranges mentioned above are considered continuous and include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Any lower limit can be combined with any upper limit to form a range not explicitly stated; and any lower limit can be combined with other lower limits to form a range not explicitly stated, just as any upper limit can be combined with any other upper limit to form a range not explicitly stated. Furthermore, each individually disclosed point or single value can itself serve as a lower or upper limit and be combined with any other point or single value or with other lower or upper limits to form a range not explicitly stated.

[0071] Although illustrative embodiments have been demonstrated and described, those skilled in the art should understand that the above embodiments should not be construed as limiting the present invention, and that changes, substitutions and modifications can be made to the embodiments without departing from the spirit, principles and scope of the present invention.

Claims

1. An electrode sheet, characterized in that, It includes a current collector (1) and an active coating (2). The current collector (1) has a first side and a second side that are arranged opposite to each other along its own thickness direction. The active coating (2) is provided on both the first side and the second side. The current collector (1) is provided with a plurality of grooves (12) and a plurality of through holes (11) at intervals, the through holes (11) connecting the first side and the second side; The through hole (11) and the groove (12) form a hole-groove array. The hole-groove array includes multiple rows of holes and grooves spaced apart along the length direction of the current collector (1). Each row of holes and grooves includes multiple through holes (11) and multiple grooves (12). The through holes (11) and grooves (12) in the same row of holes and grooves are spaced apart along the width direction of the current collector (1).

2. The electrode sheet according to claim 1, characterized in that, The diameter of the groove (12) gradually decreases from the top to the bottom of the groove (12).

3. The electrode sheet according to claim 2, characterized in that, The groove diameter at the maximum groove diameter of the groove (12) is 15um-500um.

4. The electrode sheet according to claim 1, characterized in that, The diameter of the through hole (11) is 10um-200um.

5. The electrode sheet according to claim 1, characterized in that, Within the same row of holes and grooves, the through holes (11) and the grooves (12) are alternately arranged.

6. The electrode sheet according to claim 5, characterized in that, Within the same row of holes and slots, the distance between the through hole (11) and the adjacent groove (12) is 0.2mm-10mm, and the distance between two adjacent rows of holes and slots along the length of the current collector (1) is 0.2mm-10mm.

7. An electrochemical device, characterized in that, The battery cell body (10) includes a battery cell body (10) and a lithium source (20). The battery cell body (10) includes a separator (101) and an electrode as described in any one of claims 1-6. The separator (101) is sandwiched between two adjacent electrodes. The lithium source (20) is disposed within the battery cell body (10).

8. The electrochemical device according to claim 7, characterized in that, The main body of the battery cell (10) is a wound battery cell. The main body of the battery cell (10) has a square part (102) and two arc-shaped parts (103). The two arc-shaped parts (103) are located at both ends of the width direction of the square part (102). The lithium source (20) is provided in both arc-shaped parts (103) and / or the lithium source (20) is provided at the center of the thickness direction of the square part (102).

9. The electrochemical device according to claim 7, characterized in that, The cell body (10) is a laminated cell, and the lithium source (20) is provided at the middle part of the thickness direction of the cell body (10) and / or at both ends of the thickness direction of the cell body (10).

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