A lithium-ion battery and its preparation method

Abstract

To overcome the problems of high temperature and current density near the negative electrode tab in the single-sided region of the battery, leading to lithium-ion accumulation and lithium plating, this invention provides a lithium-ion battery and its preparation method. The lithium-ion battery includes a positive electrode and a negative electrode, both of which include a current collector and an active material layer. The portion of the negative electrode with the negative electrode tab is a negative electrode tab connection portion. An etched region is formed on at least one of the active material layer adjacent to the negative electrode tab connection portion on the negative electrode or on the active material layer opposite to the negative electrode tab connection portion on the positive electrode. Multiple etching grooves are provided on the active material layer of the etched region. This invention reduces the extraction of lithium ions from the positive electrode adjacent to the negative electrode tab connection portion by providing an etched region with multiple etching grooves on the positive electrode, or provides a rapid insertion channel for lithium ions into the negative electrode near the negative electrode tab connection portion by providing an etched region on the negative electrode, thereby reducing the risk of lithium plating and improving the cycle performance and safety of the lithium-ion battery.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion battery technology, specifically relating to a lithium-ion battery and its preparation method. Background Technology

[0002] The current mobile phone battery industry has increasingly higher requirements for battery energy density. The coating density of the negative electrode is increasing, the battery system kinetics are decreasing, and the battery capacity is increasing. The charging temperature rise is increasing, and the temperature rise near the cell tab (the single-sided area of ​​the negative electrode in conventional structure) is increasing. This leads to an increase in the current density near the tab, which prevents the negative electrode from inserting lithium in time. Lithium ions undergo side reactions on the surface of the negative electrode, forming byproducts. The closer to the tab, the more byproducts there are, resulting in the loss of active lithium ions, reduced battery capacity, reduced cycle performance, and reduced safety performance.

[0003] The main reason for the generation of side reaction products in the single-sided region of the conventional negative electrode is the insufficient kinetics of the negative electrode side of the battery system. Existing technologies mainly improve the system kinetics through the following methods: reducing the negative electrode coating density, increasing the separator porosity, improving electrolyte kinetics, and reducing positive electrode kinetics. However, all existing methods have drawbacks. Reducing the negative electrode density reduces the corresponding battery capacity and energy density; increasing the separator porosity reduces battery safety performance; improving electrolyte kinetics reduces battery safety and storage performance; and reducing positive electrode kinetics reduces high-temperature cycle performance. How to improve the lithium intercalation capability of the negative electrode without sacrificing the battery's energy density is the main problem that needs to be solved. Summary of the Invention

[0004] To address the issue of high temperature and current density near the negative electrode tab in the single-sided region of the battery negative electrode in existing technologies, which easily leads to lithium ion accumulation and lithium plating, a lithium-ion battery and its preparation method are provided.

[0005] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows:

[0006] On one hand, the present invention provides a lithium-ion battery, including a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode, wherein the positive electrode, the negative electrode, and the separator are stacked or wound to form an electrode core;

[0007] Both the positive electrode and the negative electrode include a current collector and an active material layer disposed on the surface of the current collector;

[0008] The positive electrode plate also includes a positive electrode tab connected to its current collector, and the negative electrode plate also includes a negative electrode tab connected to its current collector;

[0009] The portion of the negative electrode plate where the negative electrode tab is located is the negative electrode tab connection portion;

[0010] An etched region is formed on the active material layer adjacent to the negative electrode tab connection portion on the negative electrode sheet, or on the active material layer opposite to the negative electrode tab connection portion on the positive electrode sheet; a plurality of etched grooves are provided on the active material layer of the etched region.

[0011] Optionally, the etched region includes a first negative electrode etched region formed on the negative electrode sheet, the first negative electrode etched region and the negative electrode tab being located on the same side of the negative electrode sheet, and the first negative electrode etched region being located in the region of the active material layer adjacent to the negative electrode tab connection portion; or,

[0012] The etching region includes a second negative electrode etching region formed on the negative electrode sheet. The second negative electrode etching region and the negative electrode tab are located on opposite sides of the negative electrode sheet, and the second negative electrode etching region is located in the region of the active material layer adjacent to the negative electrode tab connection portion.

[0013] Optionally, the first negative electrode etching region includes a plurality of etching grooves distributed along a direction gradually moving away from the center of the negative electrode tab connection; and / or,

[0014] The second negative electrode etching region includes a plurality of etching grooves distributed along a direction gradually moving away from the center of the negative electrode tab connection.

[0015] Optionally, the etched region includes a first positive electrode etched region formed on the positive electrode sheet; the first positive electrode etched region faces the side of the negative electrode sheet where the negative electrode tab is located; and / or,

[0016] The etched area includes a second positive electrode etched area formed on the positive electrode sheet, the second positive electrode etched area being on the side of the negative electrode sheet opposite to the negative electrode tab.

[0017] Optionally, the portion of the positive electrode plate opposite to the negative electrode tab connection portion is the negative electrode tab alignment portion;

[0018] The first positive electrode etching region includes a plurality of etching grooves distributed along a direction gradually moving away from the negative electrode tab alignment portion; and / or,

[0019] The second positive electrode etching region includes a plurality of etching grooves distributed along a direction gradually moving away from the negative electrode tab alignment portion.

[0020] Optionally, the first positive electrode etching region and / or the second positive electrode etching region may further include a plurality of etching grooves disposed on the active material layer of the negative electrode tab alignment portion.

[0021] Optionally, electrode adhesive paper is provided on the side of the positive electrode facing the negative electrode tab, and / or on the side of the positive electrode facing the negative electrode tab away from the negative electrode tab; the electrode adhesive paper is directly opposite the negative electrode tab.

[0022] Optionally, a plurality of the etching grooves are arranged in parallel at intervals on the active material layer of the corresponding etching region.

[0023] Optionally, the extension direction of the plurality of etching grooves is parallel to or coincides with the extension direction of the negative electrode tab.

[0024] Optionally, in the lithium-ion battery, the length direction of the etched area is consistent with the width direction of the negative electrode tab, and the width direction of the etched area is consistent with the length direction of the negative electrode tab.

[0025] The etching groove extends through the active material layer and along one or both sides of the extension direction of the negative electrode tab.

[0026] Optionally, on the negative electrode or the positive electrode, the length of the etched area is 50mm to 300mm, and the width of the etched area is 20mm to 150mm.

[0027] Optionally, the width of at least one of the etched areas gradually decreases along a direction away from the negative electrode tab connection.

[0028] Optionally, the maximum width of the etched area is 25mm to 85mm.

[0029] Optionally, along a direction away from the center of the negative electrode tab connection, the width of the plurality of etching grooves in at least one of the etching regions gradually decreases in the direction of electrode length extension.

[0030] Optionally, the width of the etching groove is 50μm to 200μm.

[0031] Optionally, along a direction away from the center of the negative electrode tab connection, the depth of the plurality of etching grooves in at least one of the etching regions gradually decreases in the thickness direction of the electrode sheet.

[0032] Optionally, the depth of the etching groove is 8μm to 60μm.

[0033] Optionally, the negative electrode tab is located at one end of the current collector, or the negative electrode tab is located between the two ends of the current collector.

[0034] On the other hand, the present invention provides a method for preparing a lithium-ion battery, comprising the following operations:

[0035] Obtain a negative electrode precursor and a positive electrode without the etched region; or, obtain a positive electrode precursor and a negative electrode without the etched region.

[0036] The negative electrode precursor includes a corresponding current collector, a negative electrode tab integrally connected to the current collector, and an active material layer coated on the current collector; a plurality of etching grooves are etched on the active material layer of the negative electrode precursor to obtain the negative electrode; or,

[0037] The negative electrode precursor includes a corresponding current collector and an active material layer coated on the current collector. The current collector has a negative electrode empty foil region without the active material layer. Multiple etching grooves are formed on the active material layer of the negative electrode precursor. The negative electrode tab is soldered into the negative electrode empty foil region to obtain the negative electrode sheet; or...

[0038] The negative electrode precursor includes a corresponding current collector, and an active material layer coated on the entire surface of the current collector; a portion of the active material layer of the negative electrode precursor is cleaned to expose the negative electrode empty foil area; a plurality of etching grooves are etched on the active material layer of the negative electrode precursor; the negative electrode tab is soldered in the negative electrode empty foil area; thus obtaining the negative electrode sheet;

[0039] The positive electrode precursor includes a corresponding current collector, a positive electrode tab integrally connected to the current collector, and an active material layer coated on the current collector; a plurality of etching grooves are etched on the active material layer of the positive electrode precursor to obtain the positive electrode; or,

[0040] The positive electrode precursor includes a corresponding current collector and an active material layer coated on the current collector. The current collector has a positive electrode empty foil region without the active material layer. Multiple etching grooves are formed on the active material layer of the positive electrode precursor by etching. The positive electrode tab is soldered into the positive electrode empty foil region to obtain the positive electrode sheet; or...

[0041] The positive electrode precursor includes a corresponding current collector, and an active material layer coated on the entire surface of the current collector; a portion of the active material layer of the positive electrode precursor is cleaned to expose the positive electrode empty foil area; a plurality of etching grooves are etched on the active material layer of the positive electrode precursor; the positive electrode tab is soldered in the positive electrode empty foil area; thus obtaining the positive electrode sheet;

[0042] Obtain the diaphragm;

[0043] The positive electrode, the negative electrode, and the separator are stacked or wound to form the electrode core.

[0044] Optionally, the etching method is laser etching.

[0045] The beneficial effects of this invention are as follows:

[0046] The lithium-ion battery provided by this invention forms an etching region with multiple etching grooves on the active material layer adjacent to the negative electrode tab connection portion on the negative electrode sheet or on the active material layer opposite to the negative electrode tab connection portion on the positive electrode sheet. The etching grooves on the negative electrode sheet provide insertion sites and channels for lithium ions to be inserted into the negative electrode, allowing lithium ions to be quickly inserted into the interior of the negative electrode active material layer. This also improves the negative electrode kinetics and enhances the lithium insertion capability of the negative electrode. Alternatively, the etching grooves on the positive electrode sheet reduce the extraction of lithium ions from the positive electrode adjacent to the negative electrode tab connection portion, avoiding the accumulation of lithium ions at the negative electrode tab position, reducing the risk of lithium plating, and improving the cycle performance and safety of the lithium-ion battery. Attached Figure Description

[0047] Figure 1 This is a schematic diagram of the negative electrode structure provided in an embodiment of the present invention;

[0048] Figure 2 This is a schematic diagram of the cross-sectional structure of the negative electrode sheet provided in an embodiment of the present invention;

[0049] Figure 3 This is a schematic diagram of the negative electrode structure provided in another embodiment of the present invention;

[0050] Figure 4 This is a schematic diagram of the cross-sectional structure of the negative electrode sheet provided in another embodiment of the present invention;

[0051] Figure 5 This is a schematic diagram of the negative electrode structure provided in another embodiment of the present invention;

[0052] Figure 6 This is a schematic diagram of the cross-sectional structure of the negative electrode sheet provided in another embodiment of the present invention;

[0053] Figure 7 This is a schematic diagram of another structure of the negative electrode sheet provided in another embodiment of the present invention;

[0054] Figure 8 This is a schematic diagram of another cross-sectional structure of the negative electrode sheet provided in another embodiment of the present invention;

[0055] Figure 9 This is a schematic diagram of the negative electrode structure provided in another embodiment of the present invention;

[0056] Figure 10 This is a schematic diagram of the cross-sectional structure of the negative electrode sheet provided in another embodiment of the present invention;

[0057] Figure 11 This is a schematic diagram of another structure of the negative electrode sheet provided in another embodiment of the present invention;

[0058] Figure 12 This is a schematic diagram of a positive electrode structure provided in an embodiment of the present invention;

[0059] Figure 13 This is a schematic diagram of the cross-sectional structure of the positive electrode sheet provided in an embodiment of the present invention;

[0060] Figure 14 This is a schematic diagram of another structure of the positive electrode sheet provided in another embodiment of the present invention;

[0061] Figure 15 This is a schematic diagram of another cross-sectional structure of the positive electrode sheet provided in another embodiment of the present invention;

[0062] Figure 16 This is a schematic diagram of the positive electrode structure provided in another embodiment of the present invention;

[0063] Figure 17 This is a schematic diagram of the cross-sectional structure of the positive electrode sheet provided in another embodiment of the present invention;

[0064] Figure 18 This is a schematic diagram of a positive electrode structure provided in an embodiment of the present invention;

[0065] Figure 19 This is a schematic diagram of the cross-sectional structure of the positive electrode sheet provided in an embodiment of the present invention;

[0066] Figure 20 This is a schematic diagram of another structure of the positive electrode sheet provided in another embodiment of the present invention;

[0067] Figure 21 This is a schematic diagram of another cross-sectional structure of the positive electrode sheet provided in another embodiment of the present invention;

[0068] Figure 22 This is a schematic diagram of the positive electrode structure provided in another embodiment of the present invention;

[0069] Figure 23 This is a schematic diagram of the cross-sectional structure of the positive electrode sheet provided in another embodiment of the present invention.

[0070] The reference numerals in the accompanying drawings are as follows:

[0071] 1. Current collector; 11. Active material layer; 12. Etching area; 121. Etching groove; 2. Electrode adhesive tape; 3. Positive electrode sheet; 31. Positive electrode tab; 32. First positive electrode etching area; 33. Second positive electrode etching area; 4. Negative electrode sheet; 41. Negative electrode tab; 42. First negative electrode etching area; 43. Second negative electrode etching area. Detailed Implementation

[0072] To make the technical problems solved, the technical solutions, and the beneficial effects of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0073] In the description of this invention, it should be understood that the terms "longitudinal," "radial," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0074] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0075] Reference Figures 1-23 On the one hand, the present invention provides a lithium-ion battery, including a positive electrode 3, a negative electrode 4, and a separator disposed between the positive electrode 3 and the negative electrode 4, wherein the positive electrode 3, the negative electrode 4 and the separator are stacked or wound to form an electrode core.

[0076] Both the positive electrode 3 and the negative electrode 4 include a current collector 1 and an active material layer 11 disposed on the surface of the current collector 1; specifically, the current collector 1 of the positive electrode 3 is a positive current collector, and the active material layer 11 of the positive electrode 3 is a positive active material layer, the current collector 1 of the negative electrode 4 is a negative current collector, and the active material layer 11 of the negative electrode 4 is a negative active material layer.

[0077] The positive electrode 3 also includes a positive electrode tab 31 connected to its current collector 1 (i.e., the positive current collector), and the negative electrode 4 also includes a negative electrode tab 41 connected to its current collector 1 (i.e., the negative current collector);

[0078] The part of the negative electrode plate 4 with the negative electrode tab 41 is the negative electrode tab connection part; the negative electrode tab connection part corresponds one-to-one with the negative electrode tab 41; specifically, if the negative electrode plate 4 has one negative electrode tab 41, then the negative electrode plate has one negative electrode tab connection part; if the negative electrode plate 4 has multiple negative electrode tabs 41, then the negative electrode plate has multiple negative electrode tab connection parts.

[0079] An etching region 12 is formed on the active material layer 11 (i.e., the negative electrode active material layer) adjacent to the negative electrode tab connection portion on the negative electrode sheet 4 or on the active material layer 11 (positive electrode active material layer) opposite to the negative electrode tab connection portion on the positive electrode sheet 3; a plurality of etching grooves 121 are provided on the active material layer 11 of the etching region 12.

[0080] It should be noted that the temperature rises and the current density is high near the negative electrode tab 41, causing lithium ions to accumulate near the negative electrode tab 41. These lithium ions can then undergo side reactions on the negative electrode surface, forming byproducts or lithium plating. Therefore, it is necessary to ensure that the lithium ions accumulated on the negative electrode surface can be quickly inserted into the negative electrode, or to reduce the amount of lithium ions released from the positive electrode near the negative electrode tab.

[0081] Etching is a process that forms specific patterns or textures on the surface of a material. By creating holes or grooves with a high specific surface area on the electrode, the surface properties of the material are improved and its functionality is increased. In the production of battery electrode sheets, etching can be used to increase the surface area of ​​the active material and improve its contact efficiency with the electrolyte, thereby improving the overall performance of the battery.

[0082] The lithium-ion battery provided by the present invention includes a positive electrode 3 and a negative electrode 4, both of which include a current collector 1 and an active material layer 11.

[0083] like Figures 1 to 11 An etched region 12 is formed on the active material layer 11 adjacent to the negative electrode tab connection portion on the negative electrode sheet 4. Multiple etched grooves 121 are provided on the active material layer 11 of the etched region 12. By setting the etched region 12 and multiple etched grooves 121 on the active material layer 11 of the etched region 12, the etched grooves 121 provide insertion sites and channels for lithium ions to be inserted into the negative electrode, so that lithium ions can be quickly inserted into the interior of the negative electrode active material layer. It can also improve the negative electrode dynamics and enhance the lithium insertion capability of the negative electrode. The above settings avoid the accumulation of lithium ions at the negative electrode tab 41, reduce the risk of lithium plating, and ensure that the cycle performance and safety of the lithium-ion battery are improved without reducing the energy density of the lithium-ion battery as much as possible.

[0084] like Figures 12 to 23 Alternatively, an etching region 12 is formed on the active material layer 11 on the positive electrode sheet 3 opposite to the negative electrode tab connection portion. Multiple etching grooves 121 are provided on the active material layer 11 of the etching region 12. By setting the etching region 12 and multiple etching grooves 121 on the active material layer 11 of the etching region 12, it is beneficial to reduce the extraction of lithium ions from the positive electrode near the negative electrode tab 41, avoid the accumulation of lithium ions at the negative electrode tab 41 position, reduce the risk of lithium plating, and ensure that the cycle performance and safety of the lithium-ion battery are improved without reducing the energy density of the lithium-ion battery as much as possible.

[0085] Reference Figures 1-2 , Figures 5-6 and Figures 10-11 , Figure 3 and Figure 7 ; and reference Figure 4 , Figure 8-9 On the upper side; in some embodiments, the etching region 12 includes a first negative electrode etching region 42 formed on the negative electrode sheet 4, the first negative electrode etching region 42 and the negative electrode tab 41 are located on the same side of the negative electrode sheet 4, and the first negative electrode etching region 42 is located in the region of the active material layer 11 adjacent to the negative electrode tab connection portion.

[0086] Reference Figure 4 as well as Figures 8-9 The etching region 12 includes a second negative electrode etching region 43 formed on the negative electrode sheet 4. The second negative electrode etching region 43 and the negative electrode tab 41 are located on both sides of the negative electrode sheet 4, respectively. The second negative electrode etching region 43 is located in the region of the active material layer 11 adjacent to the negative electrode tab connection.

[0087] Specifically, when the first negative electrode etching region 42 and the negative electrode tab 41 are located on the same side of the negative electrode sheet 4, and the first negative electrode etching region 42 is located in the region of the active material layer 11 adjacent to the negative electrode tab connection, during the charging process, when lithium ions are released from the positive electrode, they can quickly find the insertion site and enter the negative electrode active material. Due to the presence of the etching groove 121, lithium ions can more easily penetrate the active material layer 11, reducing the accumulation of lithium ions near the negative electrode tab 41, thereby reducing the risk of lithium plating.

[0088] When the second negative electrode etching region 43 and the negative electrode tab 41 are respectively disposed on both sides of the negative electrode sheet 4, the second negative electrode etching region 43 is located in the area of ​​the active material layer 11 adjacent to the negative electrode tab connection. By setting etching regions 12 on both sides of the negative electrode sheet 4, the flow path of lithium ions can be further dispersed, the stress and lithium deposition in the local area can be reduced, and the overall performance and life of the battery can be improved.

[0089] In some embodiments, the first negative electrode etching region 42 includes a plurality of etching grooves 121 distributed along a direction gradually moving away from the center of the negative electrode tab connection portion.

[0090] In some embodiments, the second negative electrode etching region 43 includes a plurality of etching grooves 121 distributed along a direction gradually moving away from the center of the negative electrode tab connection portion.

[0091] Specifically, the etching grooves 121 of the first negative electrode etching region 42 are distributed in a direction that gradually moves away from the center of the negative electrode tab connection portion, which helps to guide lithium ions to move and embed into the interior of the negative electrode sheet 4 starting from near the negative electrode tab 41. Similarly, the etching grooves 121 of the second negative electrode etching region 43 are distributed in a direction that gradually moves away from the center of the negative electrode tab connection portion. By utilizing the bidirectional etching grooves 121 of the first negative electrode etching region 42 and the second negative electrode etching region 43, lithium ions can be more evenly dispersed, reducing concentrated deposition near the negative electrode tab 41, thereby reducing the risk of lithium plating and further enhancing the cycle stability and safety of the battery.

[0092] Reference Figures 12-17 In some embodiments, the etching region 12 may include a first positive electrode etching region 32 formed on the positive electrode plate 3; the first positive electrode etching region 32 faces the side of the negative electrode plate 4 where the negative electrode tab 41 is provided;

[0093] Reference Figures 18-22 In some embodiments, the etching region 12 may include a second positive electrode etching region 33 formed on the positive electrode 3, the second positive electrode etching region 33 being oriented toward the side of the negative electrode 4 away from the negative electrode tab 41;

[0094] Preferably, the etching region 12 may include the first positive electrode etching region 32 and the second positive electrode etching region 33 mentioned above. The first positive electrode etching region 32 and the second positive electrode etching region 33 are respectively disposed on the two layers of the positive electrode sheet 3 adjacent to the negative electrode tab connection portion. Specifically, it may be a stack of two positive electrode sheets 3 of a stacked electrode core or a wound electrode core, with the two positive electrode sheets 3 wound on layers.

[0095] Specifically, a first positive electrode etching region 32 is provided on the positive electrode 3 facing the side of the negative electrode 4 where the negative electrode tab 41 is provided, which reduces the accumulation of lithium ions on the negative electrode active layer near the negative electrode tab 41 after they escape from the positive electrode 3, thereby reducing the risk of lithium plating. In addition, when the etching region 12 also includes a second positive electrode etching region 33 provided on the side of the negative electrode 4 away from the negative electrode tab 41, it reduces the accumulation of lithium ions on the negative electrode active layer near the negative electrode tab 41 after they escape from the positive electrode 3, thereby reducing the risk of lithium plating. Thus, by mitigating or suppressing lithium plating, the cycle stability and safety of the battery are improved.

[0096] In some embodiments, the portion of the positive electrode 3 that is opposite to the negative electrode tab connection portion is the negative electrode tab alignment portion;

[0097] The first positive electrode etching region 32 includes multiple etching grooves 121 distributed along a direction gradually moving away from the center of the negative electrode tab alignment portion; this reduces the amount of lithium delithiated from the positive electrode to the negative electrode active material layer within a certain range near the negative electrode tab, and avoids the accumulation of lithium ions on the negative electrode active layer near the negative electrode tab 41, thereby reducing the risk of lithium plating.

[0098] In some embodiments, the portion of the positive electrode sheet 3 opposite to the negative electrode tab connection portion is the negative electrode tab alignment portion; the second positive electrode etching region 33 includes a plurality of etching grooves 121 distributed along a direction gradually moving away from the center of the negative electrode tab alignment portion; reducing the amount of lithium delithiated from the positive electrode to the negative electrode active material layer within a certain range near the negative electrode tab, avoiding the accumulation of lithium ions on the negative electrode active layer near the negative electrode tab 41, thereby reducing the risk of lithium plating.

[0099] In some embodiments, electrode adhesive paper 2 is provided on the side of the positive electrode 3 facing the negative electrode tab 41; or, electrode adhesive paper 2 is provided on the side of the positive electrode 3 facing the negative electrode 4 away from the negative electrode tab 41; or, electrode adhesive paper 2 is provided on both the side of the positive electrode 3 facing the negative electrode tab 41 and the side of the positive electrode 3 facing the negative electrode 4 away from the negative electrode tab 41.

[0100] Electrode adhesive tape 2 is aligned with negative electrode tab 41.

[0101] Specifically, electrode adhesive paper 2 is provided on the side of the positive electrode 3 facing the negative electrode tab 41. In addition to playing a corresponding insulating role, it can also enhance the adhesion between electrodes, improve the structural integrity of the battery, and reduce electrode damage caused by local stress concentration.

[0102] The electrode adhesive paper 2 is placed on the side of the positive electrode 3 facing the negative electrode 4 away from the negative electrode tab 41, which also helps to enhance the structural integrity of the electrode and ensure that the battery remains stable during charging and discharging.

[0103] The arrangement of the electrode adhesive tape 2 facing the negative electrode tab 41 helps to enhance the structural stability of the battery and prevent relative movement between the electrode layers.

[0104] In some embodiments, a plurality of etching grooves 121 are disposed in parallel at intervals on the active material layer 11 of the respective etching region 12.

[0105] Specifically, the etching grooves 121 are arranged in parallel at intervals on the active material layer 11 of the corresponding etching region 12, which helps to ensure the uniform transport of lithium ions on the electrode, reduce local stress concentration, and thus improve the cycle stability and safety of the battery.

[0106] In some embodiments, the extension direction of the etching groove 121 is parallel to the extension direction of the negative electrode tab 41.

[0107] Specifically, the fact that the extension direction of the etching groove 121 is parallel to the extension direction of the negative electrode tab 41 is conducive to the rapid embedding of lithium ions at the position of the negative electrode tab 41 through the etching groove 121, improving the accumulation of lithium ions at the position of the negative electrode tab 41, or reducing the extraction of lithium ions from the positive electrode near the negative electrode tab 41, thus avoiding the accumulation of lithium ions at the position of the negative electrode tab 41.

[0108] In some embodiments, the length direction of the etched region 12 is consistent with the width direction of the negative electrode tab 41, and the width direction of the etched region 12 is consistent with the length direction of the negative electrode tab 41.

[0109] The etching groove 121 extends through one or both sides of the active material layer 11 along the extension direction of the negative electrode tab 41.

[0110] In some embodiments, on the negative electrode 4 or the positive electrode 3, the length of the etched region 12 is 50mm to 300mm, and the width of the etched region 12 is 20mm to 150mm.

[0111] Specifically, the length of the etched area 12 can be 50mm, 80mm, 100mm, 120mm, 150mm, 180mm, 230mm, 280mm or 300mm;

[0112] The width of the etched area 12 can be 20mm, 25mm, 50mm, 60mm, 75mm, 85mm, 100mm, 110mm, 120mm, 130mm or 150mm; in a preferred embodiment, the length of the etched area 12 can be set to 120mm.

[0113] In some embodiments, such as Figure 1 , Figure 3 , Figure 14 and Figure 18 Along the direction away from the center of the negative electrode connection, the width of at least one etched area 12 gradually decreases.

[0114] Specifically, when the negative electrode tab connection is located at the end of the negative electrode plate 4, the width of the etched area 12 on at least one side of the negative electrode plate 4 can be gradually reduced (e.g., ...). Figure 1 As shown), the width of the etched region 12 on at least one side of the positive electrode 3 can also be set to gradually decrease (e.g., Figure 14 (as shown)

[0115] Specifically, when the negative electrode tab connection is located between the two ends of the negative electrode plate 4, the negative electrode tab connection has an active material layer on both sides in the width direction of the negative electrode tab. The width of the etched area 12 on at least one side of the negative electrode plate 4 is largest in the middle region directly opposite the negative electrode tab in the width direction, and gradually decreases in width towards both ends of the negative electrode plate 4 in a direction away from the middle of the negative electrode tab connection (e.g., ...). Figure 3 (As shown), the width of the etched region 12 on at least one side of the positive electrode 3 can also be set such that it is largest in the middle region in the width direction opposite to the negative electrode tab, and gradually decreases in width towards both ends of the positive electrode 3 in a direction away from the middle of the negative electrode tab alignment portion (as shown). Figure 18 (As shown).

[0116] Specifically, it should be noted that the region of the negative electrode active material layer closer to the negative electrode tab connection is more prone to lithium deposition. If the width, length and depth of the etching grooves of each part of the etching region are set to be the same, it may damage the structural integrity of the electrode, making the positive electrode 3 or negative electrode 4 more prone to deformation or breakage under mechanical stress. In addition, in the battery, the electrochemical performance of the positive electrode 3 or negative electrode 4 depends on its surface area and the distribution of active materials. If the width, length and depth of the etching grooves of each part of the etching region are set to be the same, it will reduce the battery's charge and discharge efficiency, cycle stability and energy density.

[0117] Specifically, the width of at least one etched region 12 gradually decreases along the direction away from the center of the negative electrode tab connection. On the one hand, the etch grooves 121 provided on the etched region 12 of the positive electrode 3 can reduce the extraction of positive electrode lithium ions near the negative electrode tab connection. On the other hand, the etch grooves 121 provided on the etched region 12 of the negative electrode 4 provide sufficient lithium intercalation channels and sites for lithium ions near the negative electrode tab 41, avoiding the accumulation of lithium ions near the negative electrode tab 41 and causing lithium plating. At the same time, it ensures the mechanical strength and lithium intercalation capability of the positive electrode 3 or negative electrode 4 itself, and avoids deformation or breakage of the positive electrode 3 or negative electrode 4 caused by the etched region 12, or affects the energy density of the lithium-ion battery.

[0118] In some embodiments, the maximum width of the etched area 12 is 25mm to 85mm.

[0119] Specifically, the maximum width of the etched area 12 can be 25mm, 50mm, 60mm, 75mm, 83mm or 85mm;

[0120] like Figures 1-2 as well as Figures 14-15 As shown, in some embodiments of this application, the negative electrode tab 41 or the positive electrode tab 31 is disposed at one end of the current collector 1, and an etching region 12 is disposed near the negative electrode tab connection portion or the negative electrode tab alignment portion. The etching region 12 extends away from the negative electrode tab connection portion along the length direction of the current collector 1. At this time, the width of the etching region 12 is proportionally reduced from the maximum width (e.g., 25 mm) to 0. All etching grooves 121 of the etching region 12 have the same width and depth.

[0121] like Figures 3-4 as well as Figures 18-19 As shown, in some other embodiments of this application, the negative electrode tab 41 is disposed between the two ends of the current collector 1. Along the length direction of the current collector 1, the etching region 12 extends from the middle of the negative electrode tab connection portion or the middle of the negative electrode tab alignment portion to a position away from the middle of the electrode tab connection portion or the middle of the negative electrode tab alignment portion. At this time, the width of the etching region 12 is proportionally reduced from the maximum width (e.g., 25 mm) to 0, and all etching grooves 121 of the etching region 12 have the same width and depth.

[0122] In some embodiments, along the direction away from the center of the negative electrode tab connection, the width of the plurality of etching grooves 121 of at least one etching region 12 gradually decreases in the electrode length extension direction.

[0123] Specifically, when the negative electrode tab connection is located at the end of the negative electrode 4, a plurality of etching grooves 121 of the etching area 12 on at least one side of the negative electrode 4 can be provided, with the width of the grooves gradually decreasing in the electrode length extension direction (e.g., Figure 11 As shown), multiple etching grooves 121 of the etching region 12 on at least one side of the positive electrode 3 can also be configured such that the width of these grooves gradually decreases along the length extension direction of the electrode (e.g., ...). Figure 17 (as shown)

[0124] Specifically, when the negative electrode tab connection is located between the two ends of the negative electrode sheet 4, the negative electrode tab connection has an active material layer on both sides of the negative electrode tab in the width direction. The width of the etching region 12 on at least one side of the negative electrode sheet 4 is largest in the middle region directly opposite the negative electrode tab in the width direction, and extends towards both ends of the negative electrode sheet 4 in a direction away from the middle of the negative electrode tab connection. The width of the plurality of etching grooves 121 in the etching region 12 gradually decreases in the electrode sheet length extension direction (e.g., ...). Figure 9 (As shown), the width of the etching region 12 on at least one side of the positive electrode 3 can be set to be largest in the middle region of the width direction opposite to the negative electrode tab, and towards both ends of the positive electrode 3 in a direction away from the middle of the negative electrode tab alignment portion. The width of the plurality of etching grooves 121 of the etching region 12 gradually decreases in the electrode length extension direction (e.g. Figure 23 (As shown).

[0125] The purpose of providing multiple etching grooves 121 in the etching region 12 is to improve the lithium plating problem caused by the accumulation of lithium ions near the negative electrode tab. Along the direction away from the center of the negative electrode tab connection, the width of the multiple etching grooves 121 in at least one etching region 12 gradually decreases in the direction of electrode length extension. Conversely, the width of the etching grooves 121 is larger the closer to the center of the negative electrode tab connection. This helps to ensure that the positive electrode 3 passes through the wider etching grooves 121, reducing the extraction of lithium ions from the positive electrode active material layer closer to the negative electrode tab connection. It also ensures that the negative electrode 4 passes through the wider etching grooves 121, providing sufficient insertion channels for lithium ions to be inserted into the positive electrode active material layer closer to the negative electrode tab connection. At the same time, it avoids the accumulation of lithium ions at the negative electrode tab position, reduces the risk of lithium plating, and ensures that the cycle performance and safety of the lithium-ion battery are improved without reducing the energy density of the lithium-ion battery.

[0126] In some embodiments, the width of the etching groove 121 is 50 μm to 200 μm.

[0127] Specifically, the width of the etching groove 121 can be 50μm, 80μm, 100μm, 120μm, 150μm, 180μm or 200μm.

[0128] In some embodiments of this application, such as Figure 2 , Figure 4 , Figure 6 , Figure 8 as well as Figure 12 , Figure 14 , Figure 18 as well as Figure 21 As shown, regardless of whether the positive electrode tab 31 or the negative electrode tab 41 is located in the middle of the current collector 1 or both the positive electrode tab 31 and the negative electrode tab 41 are located at the ends of the current collector 1, multiple etching grooves 121 are evenly distributed in the etching area 12. In this case, the width of the multiple etching grooves 121 in the above figure is the same. Under the condition that the width of the etching grooves 121 is consistent, the width of the etching grooves 121 can be 50μm~200μm; Figure 9 , Figure 11 , Figure 17 as well as Figure 23 As shown, the widths of different etching grooves 121 in the same etching area 12 are not the same. At this time, the width of the etching groove 121 is proportionally reduced from 200μm to 50μm. Under the condition of ensuring that the electrode has a corresponding uniform stress, a suitable width is set between adjacent etching grooves 121.

[0129] In some embodiments, along a direction away from the center of the negative electrode tab connection, the depth of the plurality of etching grooves 121 of at least one etching region 12 gradually decreases in the thickness direction of the electrode sheet.

[0130] Specifically, when the negative electrode tab connection is located at the end of the negative electrode sheet 4, multiple etching grooves 121 of the etching area 12 on at least one side of the negative electrode sheet 4 can be provided with a depth that gradually decreases in the thickness direction of the electrode sheet (e.g., Figure 6 As shown), the etching region 12 on at least one side of the positive electrode 3 can also be configured such that the depth of the etching region 12 gradually decreases in the thickness direction of the electrode (e.g. Figure 13 (as shown)

[0131] Specifically, when the negative electrode tab connection is located between the two ends of the negative electrode sheet 4, the negative electrode tab connection has an active material layer on both sides in the width direction of the negative electrode tab. The width of the etching region 12 on at least one side of the negative electrode sheet 4 is largest in the middle region directly opposite the negative electrode tab, and extends towards both ends of the negative electrode sheet 4 in a direction away from the middle of the negative electrode tab connection. The depth of the plurality of etching grooves 121 in the thickness direction of the electrode sheet gradually decreases (e.g., ...). Figure 8(As shown), the width of the etching region 12 on at least one side of the positive electrode 3 can be set to be largest in the middle region of the width direction opposite to the negative electrode tab, and gradually decrease in depth in the thickness direction of the electrode 3 towards both ends of the positive electrode 3 in a direction away from the middle of the negative electrode tab alignment portion (as shown). Figure 21 (As shown).

[0132] It should be noted that the negative electrode of the battery is close to the negative electrode tab 41. The temperature rises and the current density is high. Lithium ions accumulate in this area. If the negative electrode cannot insert lithium in time, the lithium ions will undergo side reactions on the surface of the negative electrode, forming by-products or lithium plating.

[0133] Specifically, in order to solve the problems of lithium ions forming byproducts and lithium plating on the negative electrode surface due to side reactions, this application sets up an etched region 12 and etched grooves 121 in the etched region 12 to suppress excessive lithium removal from the positive electrode and provide more lithium insertion channels and sites for the negative electrode, thereby improving lithium plating. Along the direction away from the middle of the negative electrode tab connection, the depth of multiple etched grooves 121 in at least one etched region gradually decreases in the thickness direction of the electrode sheet. Taking the negative electrode tab 41 as a reference, by adjusting the depth of the etched grooves 121 that are away from and close to the negative electrode tab 41, the transport path of lithium ions inside the battery is optimized, the diffusion resistance is reduced, and the transport efficiency of lithium ions is improved.

[0134] In some embodiments, the depth of the etching groove 121 is 8 μm to 60 μm.

[0135] Specifically, the depth of the etching groove 121 can be 8μm, 10μm, 15μm, 20μm, 30μm, 40μm, 45μm, 48μm, 55μm, 60μm, 70μm, or 80μm; for example Figure 6 , Figure 8 Figure 13 as well as Figure 21 As shown, Figure 6 In the process, along the length of the current collector 1, the depth of the etching groove 121 extending away from the positive electrode tab 31 or the negative electrode tab 41 gradually decreases. At this time, the depth of the etching groove 121 is proportionally reduced from 60μm to 10μm. Figure 8 In this process, the depth of the etching groove 121 is proportionally reduced from 48 μm to 8 μm.

[0136] In some embodiments, the negative electrode tab 41 is located at one end of the current collector 1, or the negative electrode tab 41 is located between the two ends of the current collector 1.

[0137] Specifically, when the negative electrode tab 41 is located at the end of the current collector 1, it can ensure the uniform distribution of current and reduce local overheating, thereby improving the safety and cycle stability of the battery.

[0138] When the negative electrode tab 41 is located between the two ends of the current collector 1, it helps to balance the current density inside the battery and avoid electrode damage caused by current concentration.

[0139] In another embodiment of the present invention, a method for preparing a lithium-ion battery is provided, comprising the following operations:

[0140] Obtain the negative electrode precursor and the positive electrode 3 without the etching region 12;

[0141] The negative electrode precursor includes a corresponding current collector 1, a negative electrode tab 41 integrally connected to the current collector 1, and an active material layer 11 coated on the current collector 1; a plurality of etching grooves 121 are etched on the active material layer 11 of the negative electrode precursor to obtain the negative electrode 4; or,

[0142] The negative electrode precursor includes a corresponding current collector 1 and an active material layer 11 coated on the current collector 1. The current collector 1 has a negative electrode empty foil area without the active material layer 11. Multiple etching grooves 121 are etched into the active material layer 11 of the negative electrode precursor. The negative electrode tab 41 is soldered into the negative electrode empty foil area to obtain the negative electrode 4; or...

[0143] The negative electrode precursor includes a corresponding current collector 1, and an active material layer 11 coated on the entire surface of the current collector 1; the active material layer 11 of the negative electrode precursor is cleaned to expose the negative electrode empty foil area; a plurality of etching grooves 121 are etched on the active material layer 11 of the negative electrode precursor; the negative electrode tab 41 is soldered in the negative electrode empty foil area; and the negative electrode 4 is obtained.

[0144] Obtain the diaphragm;

[0145] The positive electrode 3, the negative electrode 4, and the separator are stacked or wound to form the electrode core.

[0146] Specifically, the above-mentioned method for preparing a lithium-ion battery involves etching multiple etching grooves 121 on the active material layer 11 of the negative electrode precursor. These etching grooves 121 provide more positions for lithium-ion insertion and extraction, allowing more lithium-ions to be contained inside the negative electrode rather than accumulating near the negative electrode tab 41, thus helping to reduce the risk of lithium-ion precipitation near the negative electrode tab. Whether the negative electrode sheet with the negative electrode tab 41 is integrally connected to the current collector 1, specifically by pre-reserving the negative electrode tab 41 on the current collector 1 through a die-cutting process, or by pre-reserving a negative electrode empty foil area on the current collector 1 and then welding the negative electrode sheet with the negative electrode tab 41 to the negative electrode empty foil area, the etching region 12 with etching grooves 121 can be set to improve the lithium-ion transport efficiency, thereby reducing the risk of local overcurrent and lithium precipitation caused by poor lithium-ion transport. This ensures that the cycle performance and safety of the lithium-ion battery are improved without reducing the energy density of the lithium-ion battery as much as possible.

[0147] The negative electrode empty foil area can be a region reserved when the active material layer 11 is intermittently coated on the current collector 1, or it can be a region exposed after cleaning part of the active material layer 11 on the current collector 1. The formation method of the negative electrode empty foil area does not limit the setting of the etching tank 121. Specifically, for the negative electrode empty foil area exposed after cleaning part of the active material layer 11 on the current collector 1, the negative electrode empty foil area and the etching area can be formed on the negative electrode sheet 4 by staged laser processing.

[0148] In another embodiment of the present invention, a method for preparing a lithium-ion battery is provided, comprising the following operations:

[0149] Obtain the positive electrode precursor and the negative electrode 4 without the etching region 12;

[0150] The positive electrode precursor includes a corresponding current collector 1, a positive electrode tab 31 integrally connected to the current collector 1, and an active material layer 11 coated on the current collector 1; a plurality of etching grooves 121 are etched on the active material layer 11 of the positive electrode precursor to obtain the positive electrode 3; or,

[0151] The positive electrode precursor includes a corresponding current collector 1 and an active material layer 11 coated on the current collector 1. The current collector 1 has a positive electrode empty foil region without the active material layer 11. Multiple etching grooves 121 are etched into the active material layer 11 of the positive electrode precursor. Positive electrode tabs 31 are soldered into the positive electrode empty foil region to obtain the positive electrode 3; or...

[0152] The positive electrode precursor includes a corresponding current collector 1, and an active material layer 11 coated on the entire surface of the current collector 1; the active material layer 11 of the positive electrode precursor is cleaned to expose the positive electrode empty foil area; a plurality of etching grooves 121 are etched on the active material layer 11 of the positive electrode precursor; the positive electrode tab 31 is soldered in the positive electrode empty foil area; thus obtaining the positive electrode 3.

[0153] Obtain the diaphragm;

[0154] The positive electrode 3, the negative electrode 4, and the separator are stacked or wound to form the electrode core.

[0155] Specifically, by etching multiple etching grooves 121 on the active material layer 11 of the positive electrode precursor, these etching grooves 121 can reduce the extraction of lithium ions in the region adjacent to the negative electrode tab of the positive electrode, and prevent lithium ions from accumulating near the negative electrode tab 41, thus helping to reduce the risk of lithium ions precipitating near the negative electrode tab. Whether the positive electrode 3 with the positive electrode tab 31 is integrally connected to the current collector 1, specifically by pre-reserving the positive electrode tab 31 directly on the current collector 1 through a die-cutting process, or by pre-reserving a positive electrode empty foil area on the current collector 1 and then welding the positive electrode tab 31 in the positive electrode empty foil area, the etching area 12 with etching grooves 121 can be set. The setting position of the etching area 12 is not based on the position of the positive electrode tab 31, but on the position of the negative electrode tab 41, thereby ensuring that the cycle performance and safety of the lithium-ion battery are improved without reducing the energy density of the lithium-ion battery as much as possible.

[0156] The positive electrode empty foil area can be a region reserved when the active material layer 11 is intermittently coated on the current collector 1, or it can be a region exposed by cleaning part of the active material layer 11 on the current collector 1. The formation method of the positive electrode empty foil area does not limit the setting of the etching tank 121. Specifically, for the scheme of cleaning part of the active material layer 11 exposed on the current collector 1, the positive electrode empty foil area and the etching area can be formed on the positive electrode sheet 4 by staged laser processing.

[0157] In some embodiments, the etching method is laser etching.

[0158] The present invention will be further illustrated by the following examples.

[0159] Example 1

[0160] This embodiment illustrates a lithium-ion battery and its preparation method disclosed in this invention, including the following steps:

[0161] Preparation of negative electrode:

[0162] The negative electrode precursor includes a current collector 1 and an active material layer 11 coated on the current collector 1. The current collector 1 has a negative electrode empty foil area without the active material layer 11. Multiple etching grooves 121 are etched on the active material layer of the negative electrode precursor near the negative electrode empty foil area to form an etching area. The etching area length L = 120 mm, the etching groove width W1 = 100 μm, the etching gap G = 1 mm, the etching groove depth H = 40 μm, and the etching area width W. The maximum width of the etching area is 85 mm (the width of the etching area 12 gradually decreases along the direction away from the center of the negative electrode tab connection, that is, the farther away from the center of the negative electrode tab connection, the smaller the width of the etching area, decreasing proportionally from 85 mm to 0 mm). The negative electrode tab 41 is welded in the negative electrode empty foil area to obtain the negative electrode sheet.

[0163] Preparation of positive electrode:

[0164] The positive electrode precursor includes a corresponding current collector 1 and an active material layer 11 coated on the current collector 1. The current collector 1 has a positive electrode empty foil area without the active material layer 11. Multiple etching grooves 121 are etched on the active material layer 11 of the positive electrode precursor. Positive electrode tabs 31 are welded to the positive electrode empty foil area to obtain the positive electrode 3.

[0165] Preparation of lithium-ion batteries:

[0166] The positive electrode, negative electrode, and separator are stacked or wound to form the electrode core. The electrode core is placed in a packaging bag to dry, and then injected with electrolyte. After vacuum sealing, settling, formation, and shaping, the lithium-ion battery is completed.

[0167] Example 2

[0168] This embodiment illustrates a lithium-ion battery and its preparation method disclosed in this invention, including most of the operations in Example 1, with the following differences:

[0169] On the negative electrode: no etching groove 121 is made;

[0170] The steps for preparing the positive electrode sheet also include:

[0171] Multiple etching grooves 121 are etched on the active material layer 11 of the positive electrode precursor to form an etching region. The etching region length L=120mm, the etching groove width W1=100μm, the etching gap G=1mm, the etching groove depth H=28μm, and the maximum width of the etching region is 25mm (the width of the etching region 12 gradually decreases from 25mm to 0 along the direction away from the middle of the negative electrode tab connection).

[0172] Example 3

[0173] This embodiment illustrates a lithium-ion battery and its preparation method disclosed in this invention, including most of the operations in Example 1, with the following differences:

[0174] The width of the etched area on the negative electrode is W=85mm;

[0175] On the negative electrode: the maximum depth of the etching groove is 60μm. (Along the direction away from the center of the negative electrode tab connection, the depth of the multiple etching grooves 121 in the etching area 12 in the thickness direction of the electrode gradually decreases, that is, the further away from the center of the negative electrode tab connection, the smaller the depth of the etching groove, which is proportionally reduced from 60μm to 10μm).

[0176] Example 4

[0177] This embodiment illustrates a lithium-ion battery and its preparation method disclosed in this invention, including most of the operations in Example 2, except that:

[0178] On the positive electrode: the width of the etched area W = 83 mm; the length of the etched area L = 120 mm; the width of the etch groove W1 = 100 μm; the etch gap G = 1 mm; and the maximum depth of the etch groove 51 μm (along the direction away from the center of the negative electrode connection, the depth of the multiple etch grooves 121 of the etched area 12 in the thickness direction of the electrode gradually decreases, that is, the further away from the center of the negative electrode connection, the smaller the etch depth, which is proportionally reduced from 51 μm to 8 μm).

[0179] Example 5

[0180] This embodiment illustrates a lithium-ion battery and its preparation method disclosed in this invention, including most of the operations in Example 2, except that:

[0181] On the positive electrode: the width of the etched area W = 83 mm; the length of the etched area L = 120 mm; the width of the etch groove W1 = 100 μm; the etch gap G = 1 mm; and the maximum depth of the etch groove 42 μm (along the direction away from the center of the negative electrode connection, the depth of the multiple etch grooves 121 of the etched area 12 in the thickness direction of the electrode gradually decreases, that is, the further away from the center of the negative electrode connection, the smaller the etch depth, which is proportionally reduced from 42 μm to 8 μm).

[0182] Example 6

[0183] This embodiment illustrates a lithium-ion battery and its preparation method disclosed in this invention, including most of the operations in Example 1, with the following differences:

[0184] On the negative electrode: the width of the etched area W = 85 mm; the maximum width of the etched groove is 200 μm (along the direction away from the center of the negative electrode tab connection, the width of the multiple etched grooves 121 of the etched area 12 gradually decreases in the direction of the electrode length extension, that is, the further away from the center of the negative electrode tab connection, the smaller the width of the etched groove, from 200 μm to 50 μm proportionally).

[0185] Example 7

[0186] This embodiment illustrates a lithium-ion battery and its preparation method disclosed in this invention, including most of the operations in Example 1, with the following differences:

[0187] On the negative electrode: the length of the etched area is L=50mm.

[0188] Example 8

[0189] This embodiment illustrates a lithium-ion battery and its preparation method disclosed in this invention, including most of the operations in Example 1, with the following differences:

[0190] On the negative electrode: the length of the etched area is L=300mm.

[0191] Comparative Example 1

[0192] This comparative example is used to illustrate the lithium-ion battery and its preparation method disclosed in this invention, including most of the operations in Example 1, with the following differences:

[0193] When preparing the negative electrode, no etching area is set on the negative electrode, and the negative electrode tab is located between the two ends of the current collector;

[0194] When preparing the positive electrode, no etching area is set on the positive electrode, and the positive electrode tab is located between the two ends of the current collector.

[0195] Comparative Example 2

[0196] This comparative example is used to illustrate the lithium-ion battery and its preparation method disclosed in this invention, including most of the operations in Example 1, with the following differences:

[0197] When preparing the negative electrode, no etching area is set on the negative electrode, and the negative electrode tab is located at the end of the current collector;

[0198] When preparing the positive electrode, no etching area is set on the positive electrode, and the positive electrode tab is located at the end of the current collector.

[0199] Performance testing

[0200] The following performance tests were performed on Examples 1-6 and Comparative Examples 1-2 prepared above:

[0201] Battery cycle performance test:

[0202] Test method: Charge the battery at 3C constant current and constant voltage to 4.5V, cut off at 0.05C, discharge at 0.5C, cycle 800 times, disassemble the battery, and confirm the degree of lithium plating in the cell (no lithium plating / slight lithium plating / severe lithium plating).

[0203] The test results above should be entered into Table 1.

[0204] Table 1

[0205]

[0206] As can be seen from the test results in Table 1, Examples 1 to 8 did not exhibit lithium plating, which is superior to Comparative Examples 1 and 2. This indicates that setting an etching region on the positive electrode 3 or negative electrode 4 can reduce the risk of lithium plating and improve the cycle performance and safety of lithium-ion batteries.

[0207] The energy densities of Examples 1, 3, and 6 are superior to those of Comparative Examples 1 and 2, indicating that regardless of the scheme used in Example 1 ("the width of the etched region 12 gradually decreases along the direction away from the center of the negative electrode connection"), Example 3 ("the depth of the multiple etched grooves of the etched region 12 in the thickness direction of the electrode sheet gradually decreases along the direction away from the center of the negative electrode connection"), or Example 6 ("the width of the multiple etched grooves of the etched region 12 in the length extension direction of the electrode sheet gradually decreases along the direction away from the center of the negative electrode connection"), it is possible to improve the lithium plating problem while ensuring energy density, which is beneficial to improving the cycle performance and safety of lithium-ion batteries.

[0208] The test results of Example 2 show that by reasonably designing the maximum width of the etching region 12, the decrease in energy density can be avoided as much as possible while solving the lithium plating problem.

[0209] The test results of Examples 4-5 show that by rationally designing the depth of the multiple etching grooves in the etching region 12 in the thickness direction of the electrode, the energy density decrease can be avoided as much as possible while solving the lithium plating problem.

[0210] The test results of Examples 7-8 show that with reasonable design of the etching region length L, the energy density difference is not significant and the cycle performance can meet the requirements. When the etching length is small, the etching process is simpler and the cost is reduced, but the cycle performance deteriorates. When the etching length is too large, the cycle performance is improved, but the etching time and cost increase.

[0211] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A lithium-ion battery, characterized in that, It includes a positive electrode (3), a negative electrode (4), and a separator disposed between the positive electrode (3) and the negative electrode (4). The positive electrode (3), the negative electrode (4) and the separator are stacked or wound to form an electrode core. Both the positive electrode (3) and the negative electrode (4) include a current collector (1) and an active material layer disposed on the surface of the current collector (1); The positive electrode (3) also includes a positive electrode tab (31) connected to its current collector (1), and the negative electrode (4) also includes a negative electrode tab (41) connected to its current collector (1). The part of the negative electrode plate (4) where the negative electrode tab (41) is provided is the negative electrode tab connection part; An etching region (12) is formed on the active material layer (11) of the negative electrode sheet (4) adjacent to the negative electrode tab connection portion, or on the active material layer of the positive electrode sheet (3) opposite to the negative electrode tab connection portion; a plurality of etching grooves (121) are provided on the active material layer (11) of the etching region (12).

2. A lithium-ion battery according to claim 1, characterized in that, The etched area (12) includes a first negative electrode etched area (42) formed on the negative electrode sheet (4), the first negative electrode etched area (42) and the negative electrode tab (41) being located on the same side of the negative electrode sheet (4), and the first negative electrode etched area (42) being located in the region of the active material layer (11) adjacent to the negative electrode tab connection portion; or, The etching region (12) includes a second negative electrode etching region (43) formed on the negative electrode sheet (4). The second negative electrode etching region (43) and the negative electrode tab (41) are located on opposite sides of the negative electrode sheet (4). The second negative electrode etching region (43) is located in the region of the active material layer (11) adjacent to the negative electrode tab connection.

3. A lithium-ion battery according to claim 2, characterized in that, The first negative electrode etching region (42) includes a plurality of etching grooves (121) distributed along a direction gradually moving away from the center of the negative electrode tab connection portion; and / or, The second negative electrode etching region (43) includes a plurality of etching grooves (121) distributed along a direction gradually moving away from the center of the negative electrode tab connection.

4. A lithium-ion battery according to claim 1, characterized in that, The etching region (12) includes a first positive electrode etching region (32) formed on the positive electrode plate (3); the first positive electrode etching region (32) is on the side of the negative electrode plate (4) where the negative electrode tab (41) is located; and / or, the etching region (12) includes a second positive electrode etching region (33) formed on the positive electrode plate (3), the second positive electrode etching region (33) is on the side of the negative electrode plate (4) away from the negative electrode tab (41).

5. A lithium-ion battery according to claim 4, characterized in that, The part on the positive electrode plate (3) opposite to the negative electrode tab connection part is the negative electrode tab alignment part; The first positive electrode etching region (32) includes a plurality of etching grooves (121) distributed along a direction gradually moving away from the center of the negative electrode tab alignment portion; and / or, The second positive electrode etching region (33) includes a plurality of etching grooves (121) distributed along a direction gradually moving away from the center of the negative electrode tab alignment portion.

6. A lithium-ion battery according to claim 5, characterized in that, The first positive electrode etching region (32) and / or the second positive electrode etching region (33) also include a plurality of etching grooves (121) disposed on the active material layer (11) of the negative electrode tab alignment portion.

7. A lithium-ion battery according to claim 1, characterized in that, On the side of the positive electrode (3) facing the negative electrode tab (41), and / or on the side of the positive electrode (3) facing the negative electrode (4) away from the negative electrode tab (41), there is an electrode adhesive paper (2); the electrode adhesive paper (2) is facing the negative electrode tab (41).

8. A lithium-ion battery according to claim 1, characterized in that, Multiple etching grooves (121) are arranged in parallel at intervals on the active material layer (11) of the corresponding etching area (12).

9. A lithium-ion battery according to claim 1, characterized in that, The extension direction of the plurality of etching grooves (121) is parallel or coincides with the extension direction of the negative electrode tab (41).

10. A lithium-ion battery according to any one of claims 1 to 9, characterized in that, The length direction of the etched area (12) is consistent with the width direction of the negative electrode tab (41), and the width direction of the etched area (12) is consistent with the length direction of the negative electrode tab (41). The etching groove (121) extends through one or both sides of the active material layer (11) along the extension direction of the negative electrode tab (41).

11. A lithium-ion battery according to claim 10, characterized in that, On the negative electrode (4) or the positive electrode (3): the length of the etched area (12) is 50mm~300mm, and the width of the etched area (12) is 20mm~150mm.

12. A lithium-ion battery according to claim 10, characterized in that, Along the direction away from the center of the negative electrode connection portion, the width of at least one of the etched areas (12) gradually decreases.

13. A lithium-ion battery according to claim 11, characterized in that, The maximum width of the etched area (12) is 25mm~85mm.

14. A lithium-ion battery according to claim 10, characterized in that, Along the direction away from the center of the negative electrode tab connection, the width of the plurality of etching grooves (121) of at least one of the etching regions (12) gradually decreases in the electrode length extension direction.

15. A lithium-ion battery according to claim 14, characterized in that, The width of the etching groove (121) is 50μm~200μm.

16. A lithium-ion battery according to claim 1, characterized in that, Along the direction away from the center of the negative electrode tab connection, the depth of the plurality of etching grooves (121) of at least one of the etching areas (12) gradually decreases in the thickness direction of the electrode sheet.

17. A lithium-ion battery according to claim 16, characterized in that, The depth of the etching groove (121) is 8μm~60μm.

18. A lithium-ion battery according to claim 1, characterized in that, The negative electrode tab (41) is located at one end of the current collector (1), or the negative electrode tab (41) is located between the two ends of the current collector (1).

19. A method for preparing a lithium-ion battery according to any one of claims 1 to 9, characterized in that, Includes the following operations: Obtain a negative electrode precursor and a positive electrode (3) without the etching region (12); or, obtain a positive electrode precursor and a negative electrode (4) without the etching region (12). The negative electrode precursor includes a corresponding current collector (1), a negative electrode tab (41) integrally connected to the current collector (1), and an active material layer (11) coated on the current collector (1); a plurality of etching grooves (121) are etched on the active material layer (11) of the negative electrode precursor to obtain the negative electrode (4); or, The negative electrode precursor includes a corresponding current collector (1) and an active material layer (11) coated on the current collector (1). The current collector (1) has a negative electrode empty foil area without the active material layer (11). A plurality of etching grooves (121) are etched on the active material layer (11) of the negative electrode precursor. The negative electrode tab (41) is soldered to the negative electrode empty foil area to obtain the negative electrode sheet (4). Alternatively, The negative electrode precursor includes a corresponding current collector (1) and an active material layer (11) coated on the entire surface of the current collector (1). Part of the active material layer (11) of the negative electrode precursor is cleaned to expose the negative electrode empty foil area. A plurality of etching grooves (121) are etched on the active material layer (11) of the negative electrode precursor. The negative electrode tab (41) is soldered in the negative electrode empty foil area to obtain the negative electrode (4). The positive electrode precursor includes a corresponding current collector (1), a positive electrode tab (31) integrally connected to the current collector (1), and an active material layer (11) coated on the current collector (1); a plurality of etching grooves (121) are etched on the active material layer (11) of the positive electrode precursor to obtain the positive electrode (3); or, The positive electrode precursor includes a corresponding current collector (1) and an active material layer (11) coated on the current collector (1). The current collector (1) has a positive electrode empty foil region without the active material layer (11). Multiple etching grooves (121) are etched into the active material layer (11) of the positive electrode precursor. The positive electrode tab (31) is soldered into the positive electrode empty foil region to obtain the positive electrode (3). Alternatively, The positive electrode precursor includes a corresponding current collector (1) and an active material layer (11) coated on the entire surface of the current collector (1). Part of the active material layer (11) of the positive electrode precursor is cleaned to expose the positive electrode empty foil area. A plurality of etching grooves (121) are etched on the active material layer (11) of the positive electrode precursor. The positive electrode tab (31) is soldered in the positive electrode empty foil area to obtain the positive electrode (3). Obtain the diaphragm; The positive electrode (3), the negative electrode (4) and the separator are stacked or wound to form the electrode core.

20. A method for preparing a lithium-ion battery according to claim 19, characterized in that, The etching method is laser etching.

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