Battery pole piece and battery

Abstract

The present disclosure relates to a battery pole piece and a battery. The battery pole piece comprises a current collector and an active material layer on the front and back of the current collector, and a hollow foil area which is a blank area in the active material layer. The hollow foil area comprises a first hollow foil area on the front of the current collector, a second hollow foil area on the back of the current collector, and the projection of the second hollow foil area on the front of the current collector overlaps with the first hollow foil area. A tab is located in the first hollow foil area and welded on the front of the current collector. In the length direction of the current collector, the size of the first hollow foil area is larger than the size of the second hollow foil area, and the size of the second hollow foil area is larger than the size of the tab. Through the above structure, the production failure rate caused by the fracture of the pole piece is effectively reduced. The width and area of the second hollow foil area are reduced, the load of the active material on the back of the pole piece is increased, and the energy density of the battery is improved.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of batteries, and in particular to a battery pole piece and a battery. BACKGROUND

[0002] Currently, electronic products have become an indispensable part of people's daily life, especially 3C products such as computers and mobile phones. The so-called "3C products" refer to the combination of computers, communications, and consumer electronics, also known as "information home appliances".

[0003] Among them, the endurance and charging performance of the battery in the electronic product seriously affect the user experience in the use process. Lithium ion batteries have been used as energy-providing devices, and compared with other types of batteries such as lead-acid and ternary, lithium ion batteries have higher energy density and more stable cycle life. However, due to the limitations of system materials, cell structure, and process, the energy density of lithium ion batteries is difficult to continue to improve, especially when designing for high-rate charging, the battery capacity is more difficult to meet the demand of consumers for long endurance. SUMMARY

[0004] To overcome the problems in the related art, the present disclosure provides a battery pole piece and a battery.

[0005] According to a first aspect of an embodiment of the present disclosure, a battery pole piece is provided, comprising: a current collector and an active material layer, the active material layer being located on the front and back surfaces of the current collector; and a blank foil area, which is a blank area in the active material layer; comprising: a first blank foil area located on the front surface of the current collector; a second blank foil area located on the back surface of the current collector; the projection of the second blank foil area on the front surface of the current collector forms an overlapping area with the first blank foil area; a tab located in the first blank foil area and welded on the front surface of the current collector; in the length direction of the current collector, the size of the first blank foil area is greater than the size of the second blank foil area, and the size of the second blank foil area is greater than the size of the tab.

[0006] In some embodiments, the tab is welded in the first blank foil area to form a welding area, and the overlapping area covers the welding area.

[0007] In some embodiments, in the length direction of the current collector, the size of the welding area is smaller than the size of the overlapping area.

[0008] In some embodiments, in the length direction of the current collector, at least one side of the projection of the second blank foil area on the front surface of the current collector does not overlap with both sides of the first blank foil area.

[0009] In some embodiments, in the length direction of the current collector, the projection of the second empty foil area on the front face of the current collector does not overlap with either side of the first empty foil area.

[0010] In some embodiments, in the length direction of the current collector, both sides of the projection of the second empty foil area on the front face of the current collector are between the two sides of the first empty foil area.

[0011] In some embodiments, in the length direction of the current collector, the difference between the size of the first empty foil area and the size of the tab is 3-6 mm.

[0012] In some embodiments, in the length direction of the current collector, the difference between the size of the second empty foil area and the size of the tab is 2-4 mm.

[0013] In some embodiments, the battery tab is a positive tab or a negative tab.

[0014] In some embodiments, the current collector of the positive tab is an aluminum foil, and the thickness of the current collector is 10-20 μm.

[0015] In some embodiments, the current collector of the negative tab is a copper foil, and the thickness of the current collector is 7-15 μm.

[0016] According to a second aspect of the embodiments of the present disclosure, a battery is provided, comprising the battery tab of the first aspect.

[0017] The technical solutions provided by the embodiments of the present disclosure can have the following beneficial effects: the projection of the second empty foil area forms an overlapping area with the first empty foil area, the tab is welded in the first empty foil area and in the overlapping area, so that the active material on the back of the current collector is not detached when the tab is welded, and the welding is more secure. In addition, in the length direction of the current collector, the size of the first empty foil area is greater than the size of the second empty foil area, which can reduce the size and area of the second empty foil area, increase the loading rate of the active material on the back of the tab, and improve the energy density of the battery. It can also effectively reduce the production rate due to tab breakage in production.

[0018] It should be understood that the general description above and the detailed description below are only exemplary and explanatory, and cannot limit the present disclosure. BRIEF DESCRIPTION OF DRAWINGS

[0019] The accompanying drawings, which are incorporated into and form part of the specification, illustrate embodiments consistent with the present disclosure and, together with the specification, serve to explain the principles of the present disclosure.

[0020] Figure 1 is a partial structure schematic diagram of a battery tab according to an exemplary embodiment.

[0021] Figure 2 is a schematic diagram of a partial structure of a battery electrode sheet according to another exemplary embodiment.

[0022] Figure 3 is a schematic diagram of a partial structure of a battery electrode sheet according to another exemplary embodiment.

[0023] Figure 4 is a schematic diagram of a partial structure of a battery electrode sheet according to another exemplary embodiment.

[0024] Figure 5 is a schematic diagram of a partial structure of a battery electrode sheet according to another exemplary embodiment. DETAILED DESCRIPTION

[0025] The exemplary embodiments will be described in detail herein with reference to the attached drawings. In the following description, the same numbers are used to indicate the same or similar components. The embodiments described in the following exemplary embodiments do not represent all the technical solutions consistent with the present disclosure. Instead, they are only examples of devices and methods consistent with some aspects of the present disclosure, as detailed in the appended claims.

[0026] A lithium ion battery can include a housing and an electric core. The housing is used to accommodate the electric core, and plays a protective role for the electric core.

[0027] The housing can be a soft package shell. The electric core is encapsulated in the housing by an encapsulation process, that is, a soft package electric core, which can also be referred to as a polymer electric core. The soft package shell can be an aluminum plastic film composed of a nylon layer, an aluminum layer and a plastic material layer. The nylon layer as the outermost layer of the appearance ensures the shape of the soft package shell, the aluminum layer plays a waterproof role to prevent external water from entering the electric core, and the plastic material layer melts at high temperature and has certain viscosity, and is adhered to the electric core after cooling and solidification. The plastic material layer can be polypropylene (PP), polyethylene (PE) or polypropylene terephthalate (PET).

[0028] But not limited to this, in the lithium ion battery implemented by the present disclosure, the battery housing can be plastic material or metal material. The plastic material and the metal material can have a certain hardness and can resist external impact to achieve the purpose of protecting the battery.

[0029] The electric cell can be a wound cell structure or a stacked cell structure. The electric cell can include at least one positive electrode sheet, at least one negative electrode sheet, and at least one separator layer between the positive electrode sheet and the negative electrode sheet. The positive electrode sheet and the negative electrode sheet each protrude with a positive electrode tab and a negative electrode tab to the outside of the case. In one example, the positive electrode sheet, the separator layer, and the negative electrode sheet are sequentially stacked and wound to form a wound cell structure. In another example, the positive electrode sheet, the separator layer, and the negative electrode sheet are sequentially stacked to form a stacked cell structure.

[0030] The positive electrode sheet of the electric cell includes a positive electrode base material (also referred to as a positive electrode conductive current collector), a positive electrode active material, a positive electrode tab, etc. The positive electrode base material can be a metal foil, and the positive electrode metal foil can be an aluminum foil, etc. The positive electrode base material can use an electrolytic aluminum foil having a thickness of 10 to 20 μm. The positive electrode active material can be a thin sheet made of one or more of lithium cobaltate, lithium manganate, lithium iron phosphate, and nickel cobalt manganese acid lithium (also referred to as a ternary material), which are common in the art, and the disclosure does not limit the material of the positive electrode active material. The positive electrode active material can be coated on the front and back surfaces of the positive electrode base material.

[0031] The negative electrode sheet of the battery includes a negative electrode base material (also referred to as a negative electrode conductive current collector), a negative electrode active material, a negative electrode tab, etc. The negative electrode base material can be a metal foil, and the negative electrode metal foil can be a copper foil. The negative electrode base material can use an electrolytic copper foil having a thickness of 7 to 15 μm. The negative electrode active material is made of a negative electrode active material carbon material or a non-carbon material mixed with a binder and an additive. For example, it can be a carbon negative electrode material, an alloy-based negative electrode material, a tin-based negative electrode material, a lithium-containing transition metal nitride negative electrode material, a nanoscale material, a nano negative electrode material, etc. The disclosure does not limit the material of the negative electrode layer. The negative electrode active material can be coated on the front and back surfaces of the negative electrode base material.

[0032] The positive electrode sheet or the negative electrode sheet of the battery each has a blank foil area (also referred to as a reserved blank area) where the positive electrode base material or the negative electrode base material is not coated with the positive electrode active material or the negative electrode active material. The positive electrode tab can be welded to the positive electrode base material by laser or ultrasonic welding in the first blank foil area. The negative electrode tab can be welded to the negative electrode base material by a spot welding machine in the blank foil area.

[0033] The positive electrode tab is usually an aluminum (Al) tab: generally used as a positive electrode tab, and also used as a negative electrode tab if the battery has a lithium titanate negative electrode. The negative electrode tab is usually a nickel (Ni) tab, mainly used in small digital batteries, such as mobile phone batteries, mobile power batteries, tablet computer batteries, smart delivery device batteries, etc. Copper-plated nickel (Ni-Cu) tab: used as a negative electrode tab, mainly applied to power batteries and high-rate batteries.

[0034] The isolation layer is a microporous polymer isolation film for separating the positive and negative electrode sheets, and can be made of a polymer functional material with a nanoscale microporous structure. It is used to prevent the positive and negative electrode sheets from contacting and causing short circuits, while allowing electrolyte ions to pass through and preventing electrons from passing through. The isolation layer can be a polyolefin microporous film, a polyethylene felt, a glass fiber felt, or an ultra-fine glass fiber paper commonly used in the art. The present disclosure does not limit the material of the isolation layer.

[0035] The lithium ion battery can also include an organic electrolyte that transports ions between the positive and negative electrode sheets. The organic electrolyte can be a carbonate solvent dissolved with lithium hexafluorophosphate, and the polymer uses a gel electrolyte.

[0036] The working principle of the lithium ion battery is as follows: when the battery is charged, lithium ions are generated on the positive electrode sheet of the battery, the positive active material generates lithium ions, and the generated lithium ions move to the negative electrode sheet through the electrolyte and the small holes on the isolation film. The carbon as the negative electrode substrate has a layered structure with many micropores, and the lithium ions that reach the negative electrode are embedded in the micropores of the carbon layer. The more lithium ions embedded, the higher the charging capacity. Similarly, when the battery is discharged (i.e., the process of using the battery), the lithium ions embedded in the carbon layer of the negative electrode are released, and then move back to the positive electrode through the electrolyte and the small holes on the isolation film. The more lithium ions that return to the positive electrode, the higher the discharge capacity. The battery capacity we usually refer to is the discharge capacity.

[0037] However, with the development of fast charging technology, different cell structures have emerged in addition to the original conventional structure, including the middle ear and multi-tab technology. The middle ear technology has a more complex process for welding the tabs, and both the selection of the tab welding position and the cleaning process of the corresponding active material area seriously affect the ease of manufacturing process and the performance of the finished battery. Therefore, it is necessary to fully consider increasing the proportion of active coating material when designing the cell, which not only ensures the simplicity and feasibility of the manufacturing process, but also improves the energy density of the battery.

[0038] The energy density of lithium batteries is generally compared by the battery capacity per kilogram or per liter of lithium battery. For example, the energy density of lithium ion batteries is about 120-180 Wh / kg (watt-hour / kilogram). The energy density refers to the size of the energy stored in a unit of space or mass. The energy density of the battery is the average unit volume or mass of the battery that releases electrical energy. The energy density of the battery is generally divided into two dimensions: weight energy density and volume energy density.

[0039] Battery weight energy density = battery capacity x discharge platform / weight, basic unit is Wh / kg (watt hour / kg); battery volume energy density = battery capacity x discharge platform / volume, basic unit is Wh / L (watt hour / L); the greater the energy density of the battery, the more the amount of electricity stored in the unit volume or weight.

[0040] It can be said that the energy density of the battery is the biggest bottleneck restricting the development of current lithium ion batteries. Whether it is a mobile phone or an electric vehicle, the energy density of the battery is expected to reach a new level, so that the product's endurance time or endurance mileage is no longer the main factor that hinders the product.

[0041] The following will simply explain the manufacturing process of the battery pole piece.

[0042] First step: pulp preparation. Special solvents and adhesives are used to mix with powdery positive active material and negative active material layer 20 respectively, and after high-speed stirring, the positive active material and negative active material are made into slurry.

[0043] Second step: film coating. The prepared slurry of the positive active material is uniformly coated on the front and back of the metal aluminum foil, and dried to form a positive pole piece. The prepared slurry of the negative active material is uniformly coated on the front and back of the metal copper foil, and dried to form a negative pole piece.

[0044] Third step, empty foil area manufacturing. On the basis of the positive pole piece and the negative pole piece formed after the film coating process, the active material on the metal aluminum foil or copper foil is cleaned by laser or scraping technology, and the first empty foil area and the second empty foil area are obtained.

[0045] Among them, the first empty foil area is used to weld the pole lug in the first empty foil area, and the pole lug is welded in the first empty foil area to form a welding area. The second empty foil area corresponds to the position of the first empty foil area, and when welding the pole lug, the second empty foil area is used to avoid causing the active material on the back of the current collector to fall off or produce burrs. The following will be described in detail taking the positive pole piece as an example.

[0046] The first empty foil area is respectively a first end face and a second end face at both ends of the positive active material on the front of the positive pole piece. The second empty foil area is respectively a third end face and a fourth end face at both ends of the positive active material on the back of the positive pole piece.

[0047] However, in the related art, the active material on the positive electrode tab is cleaned out of the first empty foil area used for welding the tab, and the size A in the length direction of the current collector is equal to the size C of the second empty foil area cleaned out of the active material on the back surface. And in the thickness direction of the current collector, the first end face of the first empty foil area is aligned with the third end face of the second empty foil area, and the second end face of the first empty foil area is aligned with the third end face of the second empty foil area. In this way, the first empty foil area and the second empty foil area on the front surface and the back surface of the positive electrode tab are positionally corresponding, so that the strength of the positive electrode tab at the tab welding position is reduced, the risk of tab breakage in the subsequent tab winding process is increased, and the production yield is reduced.

[0048] In addition, in the length direction of the current collector, the size C of the second empty foil area is much larger than the size B of the welding area, which can cause a lack of active material in the length direction of the positive electrode tab, a low utilization rate of the positive electrode tab in the length direction, and a loss of capacity, thereby reducing the energy density of the battery.

[0049] To solve the above technical problems, according to an embodiment of the present disclosure, a battery tab is provided, which includes: a current collector 10 and an active material layer 20, the active material layer 20 being arranged on the front surface and the back surface of the current collector 10; and an empty foil area, a region of the current collector 10 where the active material layer 20 is not coated, i.e., a blank area in the active material layer 20; the empty foil area includes a first empty foil area 31 and a second empty foil area 32, which are respectively located on the front surface and the back surface of the current collector 10; and a tab 40 welded on the front surface of the current collector 10 through the first empty foil area 31 to form a welding area. Wherein, in the length direction of the current collector 10, the size A of the first empty foil area 31 is greater than the size C of the second empty foil area 32, and the size C of the second empty foil area 32 is greater than the size B of the tab 40, and wherein, in the length direction of the current collector 10, the size B of the tab 40 is equal to the size of the welding area.

[0050] Therefore, the tab 40 of the present disclosure is welded in the first empty foil area 31, the size A of the first empty foil area 31 is greater than the size B of the tab 40, which can ensure that the tab 40 is welded in the first empty foil area 31, and the size C of the second empty foil area 32 is greater than the size B of the tab 40, which can avoid the active material layer 20 on the current collector 10 from falling off or generating burrs when the tab 40 is welded.

[0051] In addition, in the length direction of the current collector 10, the size A of the first empty foil area 31 is greater than the size C of the second empty foil area 32, so that the size C of the second empty foil area 32 and the area of the second empty foil area 32 are reduced, the load of the active material layer 20 on the back surface of the tab is increased, and the energy density of the battery is improved.

[0052] In one embodiment, the difference between the size A of the first empty foil area 31 and the size B of the tab 40 is 3-6 mm in the length direction of the current collector 10. In some embodiments, the difference between the size C of the second empty foil area 32 and the size B of the tab 40 is 2-4 mm. It should be noted that the above-mentioned size difference is only exemplary and is not intended to limit the protection scope of the present disclosure. The size difference between the first empty foil area 31 and the size B of the tab 40 can also be greater than 6 mm, and the size difference between the second empty foil area 32 and the size B of the tab 40 can also be greater than 4 mm. No specific limitation is made herein.

[0053] In some embodiments, the first empty foil area 31 and the second empty foil area 32 have an overlapping area, and the projection of the second empty foil area 32 on the front surface of the current collector 10 overlaps with the first empty foil area 31 to form the overlapping area. The size of the overlapping area is greater than the size B of the tab 40. The first empty foil area 31 and the second empty foil area 32 overlap, that is, the front surface and the back surface of the positive electrode tab are both free of the active material layer 20 at the same position after the active material layer 20 is cleaned.

[0054] Therefore, when the tab 40 is welded in the first empty foil area 31, the welding trace, such as outward protrusion or unevenness, is generated on the back surface of the metal aluminum foil of the current collector 10 by laser welding. If the active material layer 20 on the back surface of the current collector 10 is not removed, the active material layer 20 on the back surface is prone to falling off or burrs are generated on the back surface, which avoids the positive electrode tab protruding and the negative electrode tab being attached, causing the short circuit of the battery.

[0055] Therefore, the second empty foil area 32 is formed on the back surface of the positive electrode tab. On the one hand, the falling off of the active material layer 20 on the positive electrode tab and the generation of burrs on the back surface of the positive electrode tab can be avoided when the tab 40 is welded. On the other hand, the thickness during the winding of the battery can be reduced. The effective size space of the battery is more fully utilized, and the capacity and energy density of the battery are improved.

[0056] In some embodiments, a preset distance is left between the two sides of the tab 40 and the two sides of the overlapping area. On the basis of ensuring that the size A of the first empty foil area 31 is greater than the size C of the second empty foil area 32, the overlapping area between the first empty foil area 31 and the second empty foil area 32 indicates that the two ends of the first empty foil area 31 and the two ends of the second empty foil area 32 are not completely aligned in the length direction of the current collector 10, and therefore the strength of the welding area of the tab 40 at the first empty foil area 31 can be increased.

[0057] In addition, as can be seen from the above, when the tab 40 is welded, welding marks are easily generated on the back of the positive electrode sheet or the back of the positive electrode sheet is bulged. Therefore, the size of the overlapping area is larger than the size B of the tab 40. The two sides of the tab 40 and the two sides of the overlapping area are reserved with a preset distance to avoid the edge of the tab 40 being too close to the third or fourth end face of the second empty foil area 32 during welding, which would cause the active material layer 20 on the back of the positive electrode sheet near the third or fourth end face to fall off.

[0058] In some embodiments, in the length direction of the current collector 10, at least one side of the second empty foil region 32 does not overlap with both sides of the first empty foil region 31. As described above, the two ends of the first empty foil region 31 are a first end face 311 and a second end face 312, respectively. The two end faces of the second empty foil region 32 are a third end face 321 and a fourth end face 322, respectively. The fact that at least one side of the second empty foil region 32 does not overlap with both sides of the first empty foil region 31 means that in the thickness direction of the current collector 10, at least one end face of the second empty foil region 32, either the third end face 321 or the fourth end face 322, is not aligned with either the first end face 311 or the second end face 312 of the first empty foil region 31.

[0059] The positional relationship between the first empty foil area 31 and the second empty foil area 32 will be described in detail below through several embodiments.

[0060] Example 1

[0061] like Figure 1 As shown, the third end face 321 of the second empty foil area 32 is aligned with the first end face 311 of the first empty foil area 31. Since the size C of the second empty foil area 32 is smaller than the size A of the first empty foil area 31, the fourth end face 322 of the second empty foil area 32 is located between the first end face 311 and the second end face 312 of the first empty foil area 31. The size of the overlapping area between the first empty foil area 31 and the second empty foil area 32 is equal to the size C of the second empty foil area 32. The size C of the second empty foil area 32 is larger than the size B of the tab 40, thus not affecting the soldering of the tab 40.

[0062] In this embodiment, the distance from the side of the tab 40 near the first end face 311 to the first end face 311 of the first empty foil area 31 is less than the distance from the side of the tab 40 near the second end face 312 to the second end face 312 of the first empty foil area 31.

[0063] Example 2

[0064] like Figure 2As shown, the fourth end face 322 of the second empty foil region 32 is aligned with the second end face 312 of the first empty foil region 31 in the thickness direction of the current collector 10. Since the size C of the second empty foil region 32 is smaller than the size A of the first empty foil region 31, the third end face 321 of the second empty foil region 32 is located between the first end face 311 and the second end face 312 of the first empty foil region 31 in the length direction of the current collector 10. The size of the overlapping area between the first empty foil region 31 and the second empty foil region 32 is equal to the size C of the second empty foil region 32. The size C of the second empty foil region 32 is larger than the size B of the tab 40, but this will not affect the welding of the tab 40.

[0065] In this embodiment, the distance from the side of the tab 40 near the first end face 311 to the first end face 311 of the first empty foil area 31 is greater than the distance from the side of the tab 40 near the second end face 312 to the second end face 312 of the first empty foil area 31.

[0066] Example 3

[0067] like Figure 3 As shown, along the length of the current collector, neither side of the second empty foil region 32 overlaps with either side of the first empty foil region 31. That is, the third end face 321 of the second empty foil region 32 is not aligned with the first end face 311 of the first empty foil region 31 along the length of the current collector 10, and is located outside the first end face 311 and second end face 312 of the first empty foil region 31. The fourth end face 322 of the second empty foil region 32 is located between the first end face 311 and second end face 312 of the first empty foil region 31. In this case, the size of the overlapping area between the first empty foil region 31 and the second empty foil region 32 is the distance between the first end face 311 of the first empty foil region 31 and the fourth end face 322 of the second empty foil region 32.

[0068] In this embodiment, the distance from the side of the tab 40 near the first end face 311 to the first end face 311 of the first empty foil area 31 is less than the distance from the side of the tab 40 near the second end face 312 to the second end face 312 of the first empty foil area 31.

[0069] Example 4

[0070] like Figure 4 As shown, the fourth end face 322 of the second empty foil region 32 is offset from the second end face 312 of the first empty foil region 31 and is located outside the first end face 311 and the second end face 312 of the first empty foil region 31. The third end face 321 of the second empty foil region 32 is located between the first end face 311 and the second end face 312 of the first empty foil region 31. At this time, in the length direction of the current collector 10, the size of the overlapping area of ​​the first empty foil region 31 and the second empty foil region 32 is the distance between the second end face 312 of the first empty foil region 31 and the third end face 321 of the second empty foil region 32.

[0071] In this embodiment, the distance from the side of the tab 40 near the first end face 311 to the first end face 311 of the first empty foil area 31 is greater than the distance from the side of the tab 40 near the second end face 312 to the second end face 312 of the first empty foil area 31.

[0072] Example 5

[0073] like Figure 5 As shown, along the length of the current collector 10, both sides of the projection of the second empty foil region 32 onto the front surface of the current collector 10 are located within the first empty foil region 31. The third end face 321 and the fourth end face 322 of the second empty foil region 32 are both located between the first end face 311 and the second end face 312 of the first empty foil region 31. At this time, the size of the overlapping area of ​​the first empty foil region 31 and the second empty foil region 32 is the size C of the second empty foil region 32.

[0074] In this embodiment, the distance from the side of the tab 40 near the first end face 311 to the first end face 311 of the first empty foil area 31 can be equal to, less than or greater than the distance from the side of the tab 40 near the second end face 312 to the second end face 312 of the first empty foil area 31.

[0075] As can be seen from Embodiments 1 and 2, one side of the second empty foil region 32 of this disclosure is aligned with one side of the first empty foil region 31, and the other side of the second empty foil region 32 is located between the first empty foil region 31 and the second empty foil region 32. Therefore, the fact that at least one side of the second empty foil region 32 is not aligned with both sides of the first empty foil region 31 can reduce the distance between the exposed current collector 10 on the front and back sides of the positive electrode sheet, i.e., the size of the overlapping area. This can increase the strength of the misaligned front and back sides of the positive electrode sheet in the welding area of ​​the tab 40, prevent the strength of the positive electrode sheet from weakening, and avoid increasing the risk of electrode sheet breakage in subsequent sheet winding processes, which would lead to a decrease in production yield.

[0076] As can be seen from Examples 3 and 4, these are further optimizations of Examples 1 and 2, where neither end of the second empty foil region 32 is aligned with either end of the first empty foil region 31. Therefore, the strength of the welding area of ​​the tab 40 can be enhanced.

[0077] As can be seen from Example 5, it is a further optimization of Examples 3 and 4. In Example 5, both ends of the second empty foil region 32 are located within the first empty foil region 31, and neither end of the second empty foil region 32 is aligned with the end of the first empty foil region 31. This enhances the strength of the welding area of ​​the tab 40. Furthermore, since the second empty foil region 32 is located within the first empty foil region 31, the lengthwise active material layer 20 on the back side of the positive electrode increases, thereby increasing the load on the back active material layer 20 and improving the energy density of the battery.

[0078] Through the above structural design, this disclosure has the following advantages:

[0079] 1. The tab 40 is welded to the first empty foil area 31. The size A of the first empty foil area 31 is larger than the size B of the tab 40, which ensures that the tab 40 is welded within the first empty foil area 31 and effectively reduces the defect rate caused by electrode breakage during production. 2. The size C and area of ​​the second empty foil area 32 corresponding to the welding position of the tab 40 in the first empty foil area 31 are reduced, increasing the load on the active material layer 20 on the back of the electrode and improving the energy density of the battery.

[0080] Additionally, it should be noted that in this embodiment, the active material layers 20 on the front and back sides of the positive electrode can be removed using laser and scraping operations. In another embodiment, to make the size C value of the first empty foil region 31 and the second empty foil region 32 easier to control, in addition to laser removal, the first empty foil region 31 and the second empty foil region 32 can also be obtained using expanding foam.

[0081] Specifically, firstly, foamed adhesive tape is pre-applied to the predetermined position of the current collector 10. Secondly, slurry is applied to the front and back of the current collector 10 with the foamed adhesive tape pre-applied, and then it is placed in an oven to dry. After reaching the predetermined temperature, the foamed adhesive tape is thermally debonded and expands and curls. Finally, the curled foamed adhesive tape is removed to obtain an electrode with a reserved blank area, i.e., an empty foil area, and electrode tabs 40 are welded at the empty foil area.

[0082] Based on the same concept, this disclosure also provides a battery. The battery includes the positive electrode and negative electrode described above. As can be seen from the above, the manufacturing process of the battery electrode has been described in detail. After the positive electrode and negative electrode are obtained, tabs 40 are welded onto them respectively. The battery is then manufactured by performing the following steps.

[0083] Assembly steps: The positive electrode sheet → separator → negative electrode sheet → separator layer are arranged from top to bottom, wound to form the battery core, and then subjected to electrolyte injection, sealing, and other processes to complete the battery assembly process and produce a finished battery. Formation steps: The finished batteries are tested using specialized battery charging and discharging equipment. Each battery is inspected, and qualified finished batteries are selected for shipment.

[0084] It can be understood that, in order to achieve the above functions, the battery provided by the embodiments of the present disclosure includes the hardware structure and / or software module corresponding to the execution of each function. In combination with the units and algorithm steps of the examples disclosed in the embodiments of the present disclosure, the embodiments of the present disclosure can be implemented in the form of hardware or a combination of hardware and computer software. Whether a certain function is implemented in the form of hardware or computer software driving hardware depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of the technical solutions of the embodiments of the present disclosure.

[0085] As to the battery in the above embodiments, the specific manner in which each module performs operations has been described in detail in the embodiments related to the battery pole piece, and will not be described in detail here.

[0086] It can be understood that, in the present disclosure, "multiple" refers to two or more, and other quantifiers are similar. The "and / or" describes the association between the associated objects, which means that there can be three relationships, for example, A and / or B can represent: A exists alone, A and B exist together, and B exists alone. The character " / " generally represents that the associated objects before and after are in an "or" relationship. The singular form "a", "said" and "the" are also intended to include the plural form, unless the context clearly indicates otherwise.

[0087] It can be further understood that the terms "first", "second", and the like are used to describe various information, but these information should not be limited to these terms. These terms are only used to distinguish the same type of information from each other, and do not indicate a specific order or importance. In fact, the expressions "first", "second", and the like can be completely interchangeable. For example, the first information can also be referred to as the second information, and similarly, the second information can also be referred to as the first information without departing from the scope of the present disclosure.

[0088] It can be further understood that the terms "center", "longitudinal", "transverse", "front", "back", "up", "down", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the embodiments and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation.

[0089] It can be further understood that, unless otherwise specified, "connection" includes direct connection between the two without other components, and also includes indirect connection between the two with other elements.

[0090] It will be further appreciated that embodiments of the present disclosure, although described in certain order of sequences in flowcharts of the drawings, should not be construed to require that the operations be performed in the order or serially, or that all operations be performed, to achieve desirable results. In certain circumstances, multitasking and parallel processing can be advantageous.

[0091] Other embodiments of the present disclosure will be apparent to those skilled in the art from consideration of the specification and practice of the concepts disclosed herein. It is intended that the present disclosure cover any and all variations of the present disclosure including combinations of features falling within the general scope of the disclosure. The specification and examples given are intended as illustrative only and not in a limiting sense. The true scope and spirit of the present disclosure should be indicated by the following claims.

[0092] It is to be understood that the present disclosure is not limited to the precise details of design and construction described herein and illustrated in the drawings and that various modifications and changes can be made by those skilled in the art without departing from the scope of the present disclosure. The scope of the present disclosure is limited only by the claims appended hereto.

Claims

1. A battery pole piece, characterized by, The battery pole piece comprises: a current collector and an active material layer, the active material layer being located on the front and back of the current collector; and, a hollow foil area, which is a blank area in the active material layer, comprising: a first hollow foil area located on the front of the current collector; a second hollow foil area located on the back of the current collector; a projection of the second hollow foil area on the front of the current collector forms an overlapping area with the first hollow foil area; a tab located in the first hollow foil area and welded on the front of the current collector; in the length direction of the current collector, the size of the first hollow foil area is greater than the size of the second hollow foil area, and the size of the second hollow foil area is greater than the size of the tab; in the length direction of the current collector, the projection of the second hollow foil area on the front of the current collector is located between the two sides of the first hollow foil area.

2. The battery pole piece of claim 1, wherein, The tab is welded in the first hollow foil area to form a welding area, and the overlapping area covers the welding area.

3. The battery pole piece of claim 2, wherein, In the length direction of the current collector, the size of the welding area is smaller than the size of the overlapping area.

4. The battery pole piece of claim 1, wherein, In the length direction of the current collector, the difference between the size of the first hollow foil area and the size of the tab is 3-6 mm.

5. The battery pole piece of claim 1, wherein, In the length direction of the current collector, the difference between the size of the second hollow foil area and the size of the tab is 2-4 mm.

6. The battery pole piece of claim 1, wherein, The battery pole piece is a positive pole piece or a negative pole piece.

7. The battery pole piece of claim 6, wherein, The current collector of the positive pole piece is an aluminum foil, and the thickness of the current collector is 10-20 μm.

8. The battery pole piece of claim 6, wherein, The current collector of the negative pole piece is a copper foil, and the thickness of the current collector is 7-15 μm.

9. A battery, characterized by The battery pole piece comprises: The battery pole piece of any one of claims 1-8.

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