Battery pole piece, battery monomer and preparation method thereof

Abstract

The invention provides a battery pole piece, a battery monomer and a preparation method thereof, and relates to the technical field of batteries. The battery pole piece comprises a pole piece body with a coating area and a non-coating area, the coating area comprises an embossing area and two avoiding areas, and the embossing area is provided with an embossing structure; the two avoiding areas are arranged on the two sides of the embossing area in the width direction of the pole piece body, and the avoiding areas are not provided with embossing structures.

Description

Technical Field

[0001] The present disclosure relates to the field of battery technology, and in particular to a battery pole piece, a battery cell, and a method for preparing the battery cell. Background Art

[0002] In related technologies, the electrode expands during battery cell operation. To ensure a certain degree of expansion, an embossing roller is typically used to emboss the electrode surface, creating deformation space. This allows the electrode to deform during charge and discharge, thus preventing cell failure caused by electrode expansion.

[0003] However, when the battery cell is placed on its side, lithium deposition may easily occur in the corner area of ​​the battery cell, which greatly shortens the service life of the battery cell and poses a safety hazard. Summary of the Invention

[0004] The present disclosure provides a battery pole piece, a battery cell and a preparation method thereof, which at least to some extent overcome the problem in the related art that lithium deposition in the corners of a battery cell shortens the service life of the battery cell when the battery cell is placed on its side.

[0005] Other features and advantages of the present disclosure will become apparent from the following detailed description, or may be learned in part by practice of the present disclosure.

[0006] According to one aspect of the present disclosure, a battery electrode is provided, comprising a electrode body having a coated area and a non-coated area, wherein the coated area comprises an embossed area and two avoidance areas, wherein the embossed area is provided with an embossed structure; the two avoidance areas are arranged on both sides of the embossed area along the width direction of the electrode body, and the avoidance areas have no embossed structure.

[0007] In the disclosed embodiment, a battery electrode includes a electrode body having a coated area and an uncoated area. The coated area includes an embossed area and two avoidance areas, wherein the embossed area is provided with an embossed structure. The two avoidance areas are provided on either side of the embossed area along the width direction of the electrode body, and the avoidance areas are not provided with an embossed structure. By providing avoidance areas on both sides of the embossed area and not providing an embossed structure in the avoidance areas, the problem of a large gap between the electrode widths at the corners can be effectively reduced, thereby improving the dynamics of the corner area, increasing the lithium deposition window, delaying the onset of lithium deposition, and improving the safety and service life of the battery cell.

[0008] In one embodiment of the present disclosure, the width of the avoidance zone is 0.05 to 0.25 times the width of the pole piece body.

[0009] In one embodiment of the present disclosure, the embossed structure further includes a first embossed structure, and the first embossed structure is a wavy strip groove extending along the length direction of the pole piece body.

[0010] In one embodiment of the present disclosure, the cross-section of the first embossed structure is semicircular, and the radius of the semicircle is 0.1 mm to 2 mm.

[0011] In one embodiment of the present disclosure, the first embossing structure is a groove body with an inclined inner wall. Along the length direction of the pole piece body, the length of the groove body with an inclined inner wall is between 0-30 mm, and the ratio of the depth of the groove body with an inclined inner wall to the length is between 0 and 0.8.

[0012] In one embodiment of the present disclosure, the first embossing structure is a groove body having a recessed portion, the recessed portion is used to accommodate electrolyte, and along the length direction of the electrode body, the length of the groove body having the recessed portion is between 0 and 45 mm, and the ratio of the depth of the groove body having the recessed portion to the length is between 0.5 and 1.

[0013] In one embodiment of the present disclosure, the embossing structure includes a plurality of first embossing structures, and the plurality of first embossing structures are arranged along the width direction of the pole piece body.

[0014] In one embodiment of the present disclosure, the embossing structure also includes a second embossing structure, which is a blind hole arranged in an array. The protruding direction of the second embossing structure relative to the pole piece body is the same as the protruding direction of the first embossing structure relative to the pole piece body. The second embossing structure is located on the pole piece body between adjacent first embossing structures.

[0015] According to another aspect of the present disclosure, a battery cell is also provided, comprising a shell and an electrode assembly, wherein the electrode assembly comprises a positive electrode sheet, a negative electrode sheet and a separator, wherein the positive electrode sheet and / or the negative electrode sheet is the above-mentioned battery electrode sheet, and the positive electrode sheet, the separator and the negative electrode sheet are stacked and wound.

[0016] In one embodiment of the present disclosure, the width of the avoidance zone is positively correlated with the gap between adjacent electrode assemblies after winding.

[0017] In one embodiment of the present disclosure, along the winding direction of the electrode assembly, the width of the avoidance zone of the outer electrode assembly is greater than the width of the avoidance zone of the inner electrode assembly.

[0018] In one embodiment of the present disclosure, the wound electrode assembly has a flat region and a corner region, and the depth of the embossed structure in the flat region is less than the depth of the embossed structure in the corner region.

[0019] According to another aspect of the present disclosure, a method for preparing a battery cell is provided, comprising:

[0020] Providing a pole piece body having a coated area and a non-coated area, and determining a width of the avoidance area on the pole piece body;

[0021] According to the width of the avoidance area on the electrode body, an embossed area is pressed on the electrode body of the positive electrode and / or the negative electrode;

[0022] The positive electrode sheet, separator and negative electrode sheet are stacked and then wound into a shape.

[0023] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings are incorporated into and constitute a part of the specification, illustrate embodiments consistent with the present disclosure, and together with the specification, are used to explain the principles of the present disclosure. Obviously, the drawings described below are only some embodiments of the present disclosure, and those skilled in the art can derive other drawings based on these drawings without inventive effort.

[0025] Figure 1 A schematic structural diagram of an energy storage system provided by an embodiment of the present disclosure is shown.

[0026] Figure 2 A top view of a battery electrode provided by an embodiment of the present disclosure is shown.

[0027] Figure 3 A side view of a battery electrode provided by an embodiment of the present disclosure is shown.

[0028] Figure 4 A front view of a battery electrode provided by an embodiment of the present disclosure is shown.

[0029] Figure 5 A top view of another battery electrode provided by an embodiment of the present disclosure is shown.

[0030] Figure 6 A top view of another battery electrode provided by an embodiment of the present disclosure is shown.

[0031] Figure 7 Show Figure 6 Schematic diagram of the structure of the first embossed structure in the embodiment.

[0032] Figure 8 A top view of another battery electrode provided by an embodiment of the present disclosure is shown.

[0033] Figure 9 Show Figure 8 Schematic diagram of the structure of the first embossed structure in the embodiment.

[0034] Figure 10A schematic structural diagram of a battery cell provided by an embodiment of the present disclosure is shown.

[0035] Figure 11 Show Figure 10 Cross-section along the AA plane.

[0036] Figure 12 A schematic structural diagram of an electrode assembly provided in an embodiment of the present disclosure is shown.

[0037] Figure 13 A flow chart of a method for preparing a battery cell provided in an embodiment of the present disclosure is shown.

[0038] The description of the accompanying drawings is as follows:

[0039] 1. Energy storage device; 2. Electric energy conversion device; 3. First user load; 4. Second user load;

[0040] 100, battery pole piece; 110, embossed area; 111, second embossed structure; 120, avoidance area; 130, non-coating area; 140, pole tab;

[0041] 210, first embossed structure; 211, recessed portion;

[0042] 300, battery cell; 310, housing; 320, electrode assembly; 321, positive electrode sheet; 322, negative electrode sheet; 323, separator; 324, flat area; 325, corner area. DETAILED DESCRIPTION

[0043] The preferred embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although preferred embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments described herein. Rather, these embodiments are provided to make the present disclosure more thorough and complete, and to fully convey the scope of the present disclosure to those skilled in the art.

[0044] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features indicated. Thus, a feature specified as "first" or "second" may explicitly or implicitly include one or more of the specified features. Throughout the description of this application, "plurality" means two or more, unless otherwise specified.

[0045] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections, electrical connections, or mutual communication; they can refer to direct connections or indirect connections through an intermediate medium; they can refer to internal communication between two components or the interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0046] The disclosure below provides many different embodiments or examples for implementing different structures of the present application. In order to simplify the disclosure of the present application, the components and settings of specific examples are described below. Of course, these are merely examples and are not intended to limit the present application. In addition, the present application may repeat reference numbers and / or reference letters in different examples. Such repetition is for the purpose of simplicity and clarity and does not in itself indicate the relationship between the various embodiments and / or settings discussed.

[0047] Because the energy people need is highly temporal and spatially dependent, rationally utilizing energy and improving its efficiency requires a medium or device that can store one form of energy in the same form or convert it into another, allowing it to be released in a specific form based on future application needs. Currently, the primary method for generating green electricity is to develop green energy sources such as photovoltaics and wind power to replace fossil fuels.

[0048] Currently, the generation of green electricity generally relies on photovoltaics, wind power, and hydropower. However, wind and solar energy are generally intermittent and highly volatile, which can cause grid instability, insufficient electricity during peak hours, and excessive electricity during off-peak hours. Unstable voltage can also damage electricity. Therefore, insufficient electricity demand or insufficient grid capacity may lead to the problem of "wind and solar power curtailment". To solve these problems, we must rely on energy storage. This means converting electrical energy into other forms of energy through physical or chemical means and storing them. When needed, this energy is converted into electrical energy and released. Simply put, energy storage is like a large "power bank", storing electricity when photovoltaic and wind energy are sufficient and releasing the stored electricity when needed.

[0049] Taking electrochemical energy storage as an example, this solution provides an energy storage device with a group of chemical batteries. The energy storage device mainly uses the chemical elements in the batteries as energy storage media. The charging and discharging process is accompanied by chemical reactions or changes in the energy storage medium. Simply put, the electricity generated by wind and solar energy is stored in the chemical batteries. When the use of external electricity reaches its peak, the stored electricity is released for use, or transferred to places where electricity is scarce for use.

[0050] Currently, energy storage (i.e., energy storage) has a wide range of application scenarios, including power generation side energy storage, grid side energy storage, and power consumption side energy storage. The corresponding types of energy storage devices include:

[0051] (1) Large-scale energy storage power stations applied to wind power and photovoltaic power stations can help renewable energy generation meet grid connection requirements and improve the utilization rate of renewable energy. As a high-quality active / reactive power supply on the power supply side, energy storage power stations can achieve load matching of electricity in time and space, enhance the ability to absorb renewable energy, reduce instantaneous power changes, reduce the impact on the power grid, improve the absorption of new energy generation, and are of great significance in grid system backup, alleviating peak load power supply pressure, and peak and frequency regulation.

[0052] (2) Energy storage containers used on the grid side are mainly used for peak load regulation, frequency regulation, and relief of grid congestion. They can realize peak load shaving and valley filling of electricity load, that is, charging the energy storage battery when the electricity load is low and releasing the stored electricity during the peak load period, thereby achieving a balance between electricity production and consumption;

[0053] (3) Small energy storage cabinets used on the power consumption side, whose main functions are self-generation and self-use of electricity, peak-valley price arbitrage, capacity cost management, and improving power supply reliability. According to different application scenarios, energy storage on the power consumption side can be divided into industrial and commercial energy storage cabinets, household energy storage devices, energy storage charging piles, etc., which are generally used in conjunction with distributed photovoltaics. Industrial and commercial users can use energy storage for peak-valley price arbitrage and capacity cost management. In the power market that implements peak-valley electricity prices, by charging the energy storage system when the electricity price is low and discharging the energy storage system when the electricity price is high, peak-valley electricity price arbitrage is achieved, reducing electricity costs. In addition, industrial enterprises that are subject to two-part electricity prices can use energy storage systems to store energy during low electricity consumption and discharge it during peak load, thereby reducing peak power and the maximum demand reported, and achieving the purpose of reducing capacity electricity charges. Household photovoltaic storage can improve the level of self-generation and self-use of electricity. Due to high electricity prices and poor power supply stability, the demand for household photovoltaic installation is driven. Considering that photovoltaic power generation occurs during the day, while user loads are generally higher at night, deploying energy storage can better utilize photovoltaic power, increasing self-generation and self-consumption while reducing electricity costs. Furthermore, energy storage is required for backup power in areas such as communication base stations and data centers.

[0054] See Figure 1 , Figure 1 This is a structural diagram of a household energy storage system according to an embodiment of the present application. Figure 1 The embodiment is described using a home energy storage scenario in user-side energy storage as an example. The attached figure is a schematic structural diagram of a household energy storage system in the home energy storage scenario. The energy storage device of the present application is not limited to the home energy storage scenario.

[0055] The present application provides a household energy storage system, which includes an energy conversion device 2 (photovoltaic panel), a first user load 3 (street lamp), a second user load 4 (such as an air conditioner or other household appliance), and an energy storage device 1. The energy storage device 1 is a small energy storage box that can be mounted on an outdoor wall. Specifically, the photovoltaic panel can convert solar energy into electrical energy during periods of low electricity prices. The energy storage device 1 is used to store this electrical energy and supply it to street lamps and household appliances for use during peak electricity prices, or to provide power during power outages / power outages.

[0056] There can be multiple energy storage devices, connected in series or in parallel, supported and electrically connected using isolation plates (not shown). In this embodiment, "multiple" refers to two or more. An energy storage box may also be provided outside the energy storage device to accommodate the energy storage device.

[0057] Optionally, the energy storage device may include, but is not limited to, a battery cell, a battery module, a battery pack, a battery system, and the like. The actual application form of the energy storage device provided in the embodiments of this application may be, but is not limited to, the products listed, and may also be other application forms. The embodiments of this application do not impose strict restrictions on the application form of the energy storage device. The embodiments of this application are described only using the example of a battery cell as the energy storage device. When the energy storage device is a battery cell, the energy storage device may be at least one of a cylindrical battery, a prismatic battery, and the like, such as a prismatic hard-shell battery.

[0058] The battery cell 300 includes a housing 310 with a housing cavity and an electrode assembly 320 disposed within the cavity. The electrode assembly 320 is formed by stacking and winding a positive electrode sheet 321, a separator 323, and a negative electrode sheet 322. During operation, the electrode sheets of the battery assembly 320 expand during charging. To ensure a certain degree of expansion, an embossing roller is typically used to emboss the surface of the electrode sheet to provide deformation space. This allows the electrode sheet to deform during charging and discharging, thus preventing failure of the electrode assembly 320 due to the expansion of the electrode sheet.

[0059] When the battery cell 300 is placed vertically, the free electrolyte gathers at the bottom of the electrode assembly 320 under the action of gravity. When the electrode assembly 320 is placed sideways, the free electrolyte will gather at the bottom corner area 325. During the bottom corner cycle, after the solid electrolyte interphase (SEI film) is formed, the negative electrode kinetics continues to decay and the lithium plating window gradually decreases.

[0060] Furthermore, the gap Gap between adjacent electrode assemblies 320 in the corner region 325 is larger than the gap in the flat region 324, resulting in poor interfacial adhesion. Furthermore, the gap is significantly correlated with winding tension: the greater the winding tension, the smaller the gap. The large gap in the corner region 325 leads to poor dynamics and a reduced lithium deposition window.

[0061] Lithium ions will accumulate on the overhang (referring to the part of the negative electrode sheet that exceeds the positive and negative electrode sheets in the length and width direction). During the discharge process, the cathode electrode sheet at the edge of the overhang has a higher Li content, and the anode electrode sheet at the edge of the overhang caused by charging has a lower CB value, so the lithium deposition window on both sides of the electrode sheet width is reduced.

[0062] In summary, when the battery cell 300 is placed on its side (or the battery cell is placed on its side), various situations may easily lead to lithium deposition in the corner area 325 , which greatly shortens the service life of the battery cell and poses a safety hazard.

[0063] In order to at least partially solve the above technical problems, the present disclosure provides a battery electrode 100, which includes a electrode body having a coated area and a non-coated area 130, wherein the coated area includes an embossed area 110 and two avoidance areas 120, and the embossed area 110 is provided with an embossed structure; the two avoidance areas 120 are provided on both sides of the embossed area 110 along the width direction of the electrode body, and the avoidance areas 120 have no embossed structure. By providing the avoidance areas 120 on both sides of the embossed area 110, and the avoidance areas 120 have no embossed structure, the problem of a large gap Gap in the corner electrode width can be effectively reduced, thereby improving the dynamics of the corner area 325, increasing the lithium plating window, delaying the time when lithium plating occurs, and improving the safety and service life of the battery cell.

[0064] Figure 2 FIG. 1 shows a top view of a battery electrode 100 provided in an embodiment of the present disclosure. Figure 3 FIG. 1 shows a side view of a battery electrode 100 provided in an embodiment of the present disclosure. Figure 4 FIG2 shows a front view of a battery electrode 100 provided by an embodiment of the present disclosure. Figure 2-Figure 4 In one embodiment, the battery electrode 100 provided by the present disclosure includes a electrode body having a coated area and a non-coated area 130, the coated area including an embossed area 110 and two avoidance areas 120, wherein the embossed area 110 extends along the length direction of the electrode body and is located in the middle of the electrode body, and the embossed area 110 is provided with an embossed structure; the two avoidance areas 120 are arranged on both sides of the embossed area 110, and the two avoidance areas 120 and the embossed area 110 are arranged along the width direction of the electrode body, and the avoidance area 120 has no embossed structure.

[0065] The pole piece body includes a current collector (not shown in the accompanying drawings), and local coating is performed on the surface of the current collector to form a coating area and a non-coating area 130, wherein the non-coating area 130 is a non-active substance coating area, and the coating area is an active substance coating area. The surface of the current collector in the non-active substance coating area is not coated with active substance, and the surface of the current collector in the active substance coating area is coated with active substance. The current collector after local coating can be used as the pole piece body of the present invention.

[0066] For the positive electrode sheet 321, the coated active material can be one of a ternary positive electrode layer material, an iron-lithium positive electrode layer material, and a sodium ion positive electrode layer material. For the negative electrode sheet 322, the coated active material can be one of an artificial graphite material, a natural graphite material, a hard carbon material, a soft carbon material, silicon, and a metal material that can form an alloy with lithium and sodium.

[0067] An embossing area 110 and two avoidance areas 120 can be formed in the coating area on the electrode body through an embossing process. The embossing area 110 and the two avoidance areas 120 both extend along the length direction of the electrode body. The embossing area 110 and the avoidance areas 120 are both rectangular. The embossing area 110 is located in the middle of the electrode body, and the two avoidance areas 120 are respectively located on both sides of the embossing area 110. The two avoidance areas 120 and the embossing area 110 are arranged side by side along the width direction of the electrode body.

[0068] When embossing the electrode body, an embossed structure is formed only in the embossing area 110, and there is no embossed structure in the avoidance area 120, so that the embossed structure is locally distributed on the electrode body to reduce the gap introduced by the embossed structure at the edge of the electrode body, optimize the problem of the embossed structure pattern in the corner area 325 being too large, and reduce the occurrence of lithium deposition in the corner when the battery cell is placed on its side.

[0069] It should be noted that the width of the electrode body is consistent with the axis of the electrode assembly 320, and the length of the electrode body is perpendicular to the axis of the electrode assembly 320. The sideways placement of the battery cell means that the axis of the electrode assembly 320 is perpendicular to the normal direction of the support.

[0070] In addition, the battery electrode 100 further includes a tab 140 , which can be used as a lead to connect to an external circuit.

[0071] In the disclosed embodiment, the battery electrode 100 includes a electrode body having a coated area and an uncoated area 130. The coated area includes an embossed area 110 and two avoidance areas 120. The embossed area 110 is provided with an embossed structure. The two avoidance areas 120 are provided on both sides of the embossed area 110 along the width direction of the electrode body, and the avoidance areas 120 do not have an embossed structure. By providing avoidance areas 120 on both sides of the embossed area 110 and the avoidance areas 120 do not have an embossed structure, the problem of a large gap between the corner electrode widths can be effectively reduced, thereby improving the dynamics of the corner area 325, increasing the lithium plating window, delaying the time when lithium plating occurs, and improving the safety and service life of the battery cell.

[0072] The width of the avoidance zone 120 affects the lithium deposition phenomenon at the corners of the battery cell placed on its side and the charge and discharge performance of the battery cell. If the avoidance zone 120 is too narrow, it may not completely solve the lithium deposition problem. If the avoidance zone 120 is too wide, it may reduce the charge and discharge performance of the battery cell.

[0073] In one embodiment, the width of the avoidance zone 120 is 0.05 to 0.25 times the width of the electrode body. The width of the avoidance zone 120 is an empirical value determined based on the actual side discharge lithium deposition situation of the battery cell. It can improve the embossing structure in a targeted manner based on the structural characteristics of the actual battery cell corner area 325, thereby reducing the situation of lithium deposition at the side corner of the battery cell while ensuring the charge and discharge performance of the battery cell.

[0074] In the embodiment of the present disclosure, the width of the avoidance zone 120 is determined by the width of the electrode body, which can effectively solve the problem of lithium deposition in the corners of the battery cell when it is placed on its side.

[0075] In one embodiment, the embossed structure further includes a first embossed structure 210, which is a wavy strip groove extending along the length of the electrode body. The first embossed structure 210 has a larger area, thereby allowing the first embossed structure 210 to gather more electrolyte and prevent electrolyte accumulation in the battery cell.

[0076] The wavy strip grooves refer to long strip grooves with a smooth curved bottom surface of the first embossed structure 210 . The smooth curve may be any curve, such as a sine line, a cosine line, a wavy line, and the like.

[0077] In one embodiment, the first embossed structure 210 is a smooth curved groove body that undulates along the thickness direction of the electrode body. On the one hand, the first embossed structure 210 extends along the length direction of the electrode body, which can make the electrolyte gather in the first embossed structure 210 and away from the avoidance area 120, thereby reducing the phenomenon of lithium deposition in the corners of the battery cell placed on its side; on the other hand, the first embossed structure 210 is a smooth curved groove body that undulates along the length direction, which can increase the effective length of the first embossed structure 210, thereby achieving better aggregation of the electrolyte.

[0078] In one embodiment, each first embossed structure 210 includes a plurality of interconnected grooves. The first embossed structure 210 is formed by pressing the pole piece body along the thickness direction of the pole piece body with an embossing roller. The embossing roller is provided with a protrusion matching the first embossed structure 210 .

[0079] like Figure 5 As shown, the cross section of the first embossed structure 210 can be semicircular, and the radius of the semicircle is 0.1mm to 2mm. After a plurality of semicircular grooves are sequentially connected along the length direction of the pole piece body, the first embossed structure 210 is obtained.

[0080] The aforementioned multiple interconnected tank bodies refer to multiple interconnected tank bodies in which the electrolyte can flow. There are many ways to achieve interconnected tank bodies, which are not specifically limited in this disclosure.

[0081] Figure 6 A top view of another battery electrode sheet 100 provided in an embodiment of the present disclosure is shown. Figure 7 Show Figure 6 Schematic diagram of the structure of the first embossed structure 210 in the embodiment. Figure 6-Figure 7 As shown, the first embossed structure 210 includes a plurality of periodic grooves along the length direction of the pole piece body. The first embossed structure 210 is a groove with an inclined inner wall. The length c of a groove with an inclined inner wall is between 0 and 30 mm, and the ratio of the depth d of a groove with an inclined inner wall to the length c is between 0 and 0.8.

[0082] In one embodiment, the cross-section of the trough body with an inclined inner wall can be V-shaped, and the cross-section of the trough body with an inclined inner wall can also be a V-shaped structure, such as the inner wall of the trough body with an inclined inner wall is a structure distributed along a sine line or a cosine line, or the bottom of the trough body with an inclined inner wall is a smooth bottom surface.

[0083] Figure 8 A top view of another battery electrode sheet 100 provided in an embodiment of the present disclosure is shown. Figure 9 Show Figure 8 Schematic diagram of the structure of the first embossed structure 210 in the embodiment. Figure 8-Figure 9 As shown, the first embossed structure 210 includes a plurality of grooves periodically arranged along the length direction of the pole piece body, and the plurality of grooves are interconnected. The first embossed structure 210 is a groove having a recessed portion 211. Along the length direction of the pole piece body, the length f of the groove having the recessed portion is between 0 and 45 mm, and the ratio of the depth e of the groove having the recessed portion to the length f is between 0.5 and 1. It should be noted that the recessed portion can be provided at the bottom of the groove.

[0084] In the embodiment of the present disclosure, by providing the first embossed structure 210 on the battery electrode 100, the adsorption capacity of the battery electrode 100 for the electrolyte can be improved, the aggregation of the electrolyte at the bottom of the battery cell can be reduced, and the lithium deposition window can be improved.

[0085] The area of ​​the first embossed structure 210 is larger, and the shape of the first embossed structure 210 can be determined according to actual conditions. In the present disclosure, by setting the first embossed structure 210, the infiltration effect of the electrolyte can be improved, so that the electrolyte covers the entire plane of the battery cell. At the same time, the first embossed structure 210 can increase the resistance of the electrolyte to downward aggregation under the action of gravity, thereby avoiding the electrolyte from gathering in the corner area 325 when the battery cell is placed on its side.

[0086] like Figure 5 、 Figure 6 and Figure 8 As shown, the embossed structure includes multiple first embossed structures 210, which are arranged along the width of the electrode body. The multiple first embossed structures 210 are arranged parallel to each other and are not connected to each other. It should be noted that the number of first embossed structures 210 can be determined according to the width of the battery electrode 100 and is not specifically limited in this disclosure.

[0087] In the embodiment of the present disclosure, by providing a plurality of first embossed structures 210 arranged along the width direction of the electrode body, it is possible to achieve reasonable distribution of the electrolyte, enable the electrolyte to be guided, and improve the infiltration effect of the electrolyte.

[0088] In some possible implementations, continue to refer to Figure 2-Figure 4 The embossed structure further includes a second embossed structure 111, which is a blind hole arranged in an array. The second embossed structure 111 can be a plurality of blind holes formed in the embossed area 110, and the plurality of blind holes are arranged in an array. The inner wall of the blind hole can be a hemispherical surface, a cylindrical surface, a conical surface, etc., which is not specifically limited in this disclosure.

[0089] The first embossed structure 210 and the second embossed structure 111 are oriented in the same direction relative to the electrode body. It should be noted that the first embossed structure 210 and the second embossed structure 111 can be embossed simultaneously during the embossing process of the battery electrode 100, and only embossing rollers that match the first embossed structure 210 and the second embossed structure 111 are required. This is not limited in the present disclosure.

[0090] The second embossed structure 111 is disposed on the electrode body between adjacent first embossed structures 210, or can also be disposed on the electrode body between the first embossed structure 210 and the avoidance area 120, depending on actual conditions. The second embossed structure 111 can provide deformation space for the electrode during charging and discharging of the battery cell, preventing failure caused by battery cell expansion, and can adjust the core size and the misalignment of the tab 140, thereby improving the electrolyte infiltration effect.

[0091] Figure 10 A schematic structural diagram of a battery cell 1 provided in an embodiment of the present disclosure is shown. Figure 11 Show Figure 10 The cross-section along the AA plane. Figure 10 and Figure 11 As shown, in one embodiment, the battery cell 1 provided by the present disclosure includes a shell 310 and an electrode assembly 320 placed in the shell 310, wherein the electrode assembly 320 includes a positive electrode sheet 321, a negative electrode sheet 322 and a separator 323, the positive electrode sheet 321 and / or the negative electrode sheet 322 is the above-mentioned battery electrode sheet 100, and the positive electrode sheet 321, the separator 323 and the negative electrode sheet 322 are stacked and wound to form the electrode assembly 320.

[0092] In one embodiment, the negative electrode sheet 322 can be the battery electrode sheet 100 provided with the avoidance area 120 and the embossed area 110, and the positive electrode sheet 321 is a electrode sheet without an embossed structure; alternatively, the positive electrode sheet 321 can also be the battery electrode sheet 100 provided with the avoidance area 120 and the embossed area 110, and the negative electrode sheet 322 is a electrode sheet without an embossed structure; or both the positive electrode sheet 321 and the negative electrode sheet 322 are the battery electrode sheets 100 provided with the avoidance area 120 and the embossed area 110. All of the above electrode sheet configurations can serve the purpose of increasing the lithium deposition window.

[0093] In combination with the above-mentioned battery electrode 100, by setting avoidance areas 120 on both sides of the embossed area 110, and the avoidance areas 120 have no embossed structure, the problem of large gap between the corner electrode pieces can be effectively reduced, thereby improving the dynamics of the corner area 325, increasing the lithium deposition window, delaying the time when lithium deposition occurs, improving the safety of the battery cell and the service life of the battery cell, improving the safety of the battery cell, and reducing safety hazards.

[0094] In one embodiment, the width of the avoidance zone 120 is positively correlated with the gap between adjacent electrode assemblies 320 after winding, that is, the larger the gap between adjacent electrode assemblies 320 after winding, the larger the width of the avoidance zone.

[0095] When the gap between adjacent electrode assemblies 320 is larger, the lithium ion transmission path is longer, and lithium deposition is more likely to occur. By setting the width of the avoidance zone 120 to be positively correlated with the gap between adjacent electrode assemblies 320 after winding, the lithium ion transmission path can be effectively reduced and the occurrence of lithium deposition can be avoided.

[0096] In a feasible embodiment, along the winding direction of the electrode assembly 320 , the width of the avoidance zone 120 of the outer electrode assembly is greater than the width of the avoidance zone 120 of the inner electrode assembly.

[0097] During the winding process of the battery electrode 100, the winding tension of the outer electrode assembly 320 gradually decreases. The smaller winding tension can make the battery electrode 100 loosely wound, resulting in the gap of the outer electrode assembly 320 to increase compared with the inner electrode assembly 320. Therefore, the outer electrode assembly 320 is set with a larger avoidance area 120 width, while the inner electrode assembly 320 is set with a smaller avoidance area 120 width.

[0098] It should be noted that the method of determining the width of the avoidance zone 120 by the width of the electrode body, the method of determining the width of the avoidance zone 120 by the gap between adjacent electrode assemblies 320 after winding, and the method of determining the width of the avoidance zone 120 by the position of each layer of electrode assembly 320 in the battery cell 1 can be implemented separately or in combination. When the widths of the avoidance zone 120 obtained by the two are different, the larger value of the two widths can be used as the width of the avoidance zone 120.

[0099] In the embodiment of the present disclosure, the width of the avoidance zone 120 is determined by the gap between adjacent electrode assemblies 320 after winding, the position of each layer of electrode assembly 320 in the battery cell 1, etc., which can effectively solve the problem of lithium deposition in the corners of the battery cell when placed on its side.

[0100] In one embodiment, the positive electrode sheet 321 and the negative electrode sheet 322 are respectively the battery electrode sheets 100, the second embossed structures 111 of the positive electrode sheet 321 and the negative electrode sheet 322 are correspondingly wound, and the avoidance areas 120 of the positive electrode sheet 321 and the negative electrode sheet 322 are correspondingly wound. When the positive electrode sheet 321 and the negative electrode sheet 322 both adopt the above-mentioned battery electrode sheet 100 with the embossed area 110 and two avoidance areas 120, the second embossed structures 111 and the avoidance areas 120 of the positive and negative electrode sheets 322 can be wound respectively, which can reduce the lithium deposition phenomenon in the corner area 325 of the side discharge cell, reduce the risk of internal short circuit caused by lithium deposition piercing the diaphragm 323, improve the safety performance of the battery cell in the later stage of the cycle, and improve the service life of the long-cycle battery cell.

[0101] In one embodiment, the positive electrode sheet 321 and the negative electrode sheet 322 are respectively the battery electrode sheet 100, the second embossed structure 111 of the positive electrode sheet 321 and the negative electrode sheet 322 is wound correspondingly, the avoidance area 120 of the positive electrode sheet 321 and the negative electrode sheet 322 is wound correspondingly, and the first embossed structure 210 of the positive electrode sheet 321 and the negative electrode sheet 322 is wound correspondingly. When both the positive and negative electrode sheets 322 have the above-mentioned embossed area 110 and two avoidance areas 120 and the second embossed structure is provided in the embossed area 110 111 and the first embossed structure 210 of the battery pole piece 100, the second embossed structure 111 and the first embossed structure 210 can help the electrolyte in the battery cell to infiltrate, increase the resistance of the electrolyte to downward aggregation under the action of gravity, and further add a recessed portion 211 to the first embossed structure 210 can enhance the adsorption and accumulation of the electrolyte on the battery pole piece 100, thereby effectively reducing the aggregation of the electrolyte at the bottom of the battery cell and avoiding the occurrence of lithium deposition at the bottom of the battery cell when it is placed on its side.

[0102] For a square battery cell, the overall shape is as follows Figure 11 The Hui shape in . Figure 12 As shown, the electrode assembly 320 includes a flat area 324 and a corner area 325 , wherein the flat area 324 may also be referred to as a large surface area.

[0103] After the electrode assembly 320 is wound and formed, the flat area 324 of the electrode assembly 320 can be hot pressed. The hot pressing process parameters can be: pressure of 3000N to 10000N, process temperature of 25°C to 115°C, and time of 30s to 300s. Through the hot pressing process, the depth of the embossed structure in the flat area 324 can be made smaller than the depth of the embossed structure in the corner area 325. The smaller embossed structure depth in the flat area 324 does not affect the insertion of the battery cell into the shell. The larger embossed structure depth in the corner area 325 provides more space for the expansion of the battery electrode 100, thereby reducing the risk of wrinkling and failure caused by excessive self-binding force of the electrode in the corner area 325.

[0104] Figure 13 A flow chart of a method for preparing a battery cell according to an embodiment of the present disclosure is shown. Figure 13 As shown, the present disclosure provides a method for preparing a battery cell, which mainly includes the following steps:

[0105] S1302, providing a pole piece body having a coating area and a non-coating area 130, and determining the width of the avoidance area 120 on the pole piece body;

[0106] S1304, according to the width of the avoidance area 120 on the electrode body, embossing the embossed area 110 on the electrode body of the positive electrode 321 and / or the negative electrode 322;

[0107] S1306 , stacking the positive electrode sheet 321 , the separator 323 and the negative electrode sheet 322 and winding them into a shape.

[0108] In the embodiment of the present disclosure, by setting avoidance areas 120 on both sides of the embossed area 110, and the avoidance areas 120 have no embossed structure, the problem of large gap between corner pole pieces Gap can be effectively reduced, thereby improving the dynamics of the corner area 325, increasing the lithium deposition window, delaying the time when lithium deposition occurs, and improving the safety and service life of the battery cell.

[0109] In S1302, as previously described, the width of the avoidance zone 120 may be determined by the width of the electrode body, the gap between adjacent electrode assemblies 320, the position of each layer of electrode assembly in the battery cell, or a combination of the three aforementioned methods. For example, the larger of the two methods of determining the width of the avoidance zone 120 by the width of the electrode body and the gap between adjacent electrode assemblies 320 may be used as the width of the avoidance zone 120.

[0110] In one embodiment, the negative electrode sheet 322 can be the battery electrode sheet 100 provided with the avoidance area 120 and the embossed area 110, and the positive electrode sheet 321 is a electrode sheet without an embossed structure; alternatively, the positive electrode sheet 321 can also be the battery electrode sheet 100 provided with the avoidance area 120 and the embossed area 110, and the negative electrode sheet 322 is a electrode sheet without an embossed structure; or both the positive electrode sheet 321 and the negative electrode sheet 322 are the battery electrode sheets 100 provided with the avoidance area 120 and the embossed area 110. All of the above electrode sheet configurations can serve the purpose of increasing the lithium deposition window.

[0111] In the present disclosure, the narrowing of the embossing structure can be achieved by narrowing the embossing rollers on both sides, and the embossing rollers are provided with patterns corresponding to the second embossing structure 111 and the first embossing structure 210, thereby forming an embossing area 110 and an avoidance area 120 on the pole piece body, as well as the second embossing structure 111 and the first embossing structure 210 formed in the embossing area 110.

[0112] When preparing a battery cell, the positive electrode sheet 321 and / or the negative electrode sheet 322 can be embossed, and then the positive electrode sheet 321, the separator 323 and the negative electrode sheet 322 can be connected into a whole. At this time, the embossed area 110 of the electrode body of the positive electrode sheet 321 and / or the negative electrode sheet 322 can protrude in the direction close to the separator 323 or protrude in the direction away from the separator 323. Finally, the positive electrode sheet 321, the separator 323 and the negative electrode sheet 322 are stacked and wound into shape to obtain the electrode assembly 320.

[0113] In the application examples, the terms "first", "second", and "third" are used for descriptive purposes only and are not to be understood as indicating or implying relative importance; the term "plurality" refers to two or more, unless otherwise expressly defined. Terms such as "installed", "connected", "connected", and "fixed" should be understood in a broad sense. For example, "connected" can mean a fixed connection, a detachable connection, or an integral connection; "connected" can mean a direct connection or an indirect connection through an intermediate medium. For those skilled in the art, the specific meanings of the above terms in the application examples can be understood according to the specific circumstances.

[0114] In the description of the application embodiments, it should be understood that the terms "up", "down", "left", "right", "front", "back", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the application embodiments and simplifying the description, and do not indicate or imply that the device or unit referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they cannot be understood as limitations on the application embodiments.

[0115] Throughout this specification, terms such as "one embodiment," "some embodiments," and "specific embodiments" mean that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the claimed invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0116] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A battery electrode, characterized in that: The invention comprises a pole piece body having a coating area and a non-coating area (130), wherein the coating area comprises an embossing area (110) and two avoidance areas (120), wherein: The embossed area (110) is provided with an embossed structure; The two avoidance areas (120) are arranged on both sides of the embossed area (110) along the width direction of the pole piece body, and the avoidance areas (120) have no embossed structure.

2. The battery electrode according to claim 1, characterized in that: The width of the avoidance area (120) is 0.05 to 0.25 times the width of the pole piece body.

3. The battery electrode according to claim 1, characterized in that: The embossed structure comprises a first embossed structure (210), wherein the first embossed structure (210) is a wavy strip groove extending along the length direction of the pole piece body.

4. The battery electrode according to claim 3, characterized in that: The cross section of the first embossed structure (210) is semicircular, and the radius of the semicircle is 0.1 mm to 2 mm.

5. The battery electrode according to claim 3, characterized in that: The first embossed structure (210) is a groove body with an inclined inner wall. Along the length direction of the pole piece body, the length of the groove body with the inclined inner wall is between 0 and 30 mm, and the ratio of the depth of the groove body with the inclined inner wall to the length is between 0 and 0.

8.

6. The battery electrode according to claim 3, characterized in that: The first embossed structure (210) is a groove body with a recessed portion, the recessed portion is used to accommodate electrolyte, and along the length direction of the electrode body, the length of the groove body with the recessed portion is between 0 and 45 mm, and the ratio of the depth of the groove body with the recessed portion to the length is between 0.5 and 1.

7. The battery electrode according to claim 3, characterized in that: The embossed structure comprises a plurality of first embossed structures (210), and the plurality of first embossed structures (210) are arranged along the width direction of the pole piece body.

8. The battery electrode according to any one of claims 3 to 7, characterized in that: The embossed structure further includes a second embossed structure (111), which is a blind hole arranged in an array. The protruding direction of the second embossed structure (111) relative to the pole piece body is the same as the protruding direction of the first embossed structure (210) relative to the pole piece body. The second embossed structure (111) is located on the pole piece body between adjacent first embossed structures (210).

9. A battery cell, characterized in that: The invention comprises a shell (310) and an electrode assembly (320), wherein the electrode assembly comprises a positive electrode sheet (321), a negative electrode sheet (322) and a separator (323), wherein the positive electrode sheet (321) and / or the negative electrode sheet (322) is a battery electrode sheet (100) according to any one of claims 1 to 8, and the positive electrode sheet (321), the separator (323) and the negative electrode sheet (322) are stacked and wound.

10. The battery cell according to claim 9, characterized in that The width of the avoidance zone (120) is positively correlated with the gap between adjacent electrode assemblies (320) after winding.

11. The battery cell according to claim 9 or 10, characterized in that: Along the winding direction of the electrode assembly (320), the width of the avoidance zone of the outer electrode assembly is greater than the width of the avoidance zone of the inner electrode assembly.

12. The battery cell according to claim 9, characterized in that The wound electrode assembly (320) has a flat area (324) and a corner area (325), and the depth of the embossed structure in the flat area (324) is smaller than the depth of the embossed structure in the corner area (325).

13. A method for preparing a battery cell, characterized in that: include: Providing a pole piece body having a coating area and a non-coating area (130), and determining the width of an avoidance area (120) on the pole piece body; According to the width of the avoidance area (120) on the electrode body, an embossed area (110) is pressed on the electrode body of the positive electrode (321) and / or the negative electrode (322); The positive electrode sheet (321), the separator (323) and the negative electrode sheet (322) are stacked and then wound into a shape.

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