Battery cell and battery

Abstract

The invention belongs to the technical field of batteries, and discloses a battery cell and a battery, the battery cell is formed by winding a pole piece and a diaphragm along a first direction, the pole piece comprises a body layer and an active substance layer coated on at least one surface of the body layer, the battery cell comprises a stress concentration area and a straight area, the stress concentration area is formed by bending the pole piece, and the straight area is formed by bending the pole piece. An adhesive tape is adhered to the surface of the pole piece, at least part of the adhesive tape is arranged in the stress concentration area, in the second direction, at least one end of the adhesive tape exceeds the pole piece, the adhesive tape comprises a base material layer and an adhesive layer, the base material layer comprises a non-adhesive area exceeding the adhesive layer, the body layer further comprises an inactive material area, and the adhesive layer and the inactive material area are at least partially overlapped. In the first direction, the stripping force of the adhesive layer and the pole piece is F, the proportion of the area of the non-adhesive area to the area of the base material layer is A, and the height of the adhesive tape exceeding the pole piece in the second direction is d, F, A and d, which meet the relational expression that (F * A) / d is greater than or equal to 0.4 * 10 <-2 > and less than or equal to 241.7 * 10 <-2 >, and the working reliability of the battery cell is relatively high.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and more particularly to a battery cell and a battery. Background Technology

[0002] With the development of battery technology, users have increasingly higher demands for the energy density of battery cells, leading to continuous increases in cell thickness. During the cell manufacturing process, stress concentration occurs at the bent portions of the electrodes, making it easier for active material to detach, resulting in a decrease in battery capacity. Applying protective tape to the bent portions can reduce the risk of material detachment, but during use, it has been found that the tape sometimes detaches, actually exacerbating the risk. Summary of the Invention

[0003] The present invention discloses a battery cell and a battery that can ensure that the tape is stably bonded to the stress concentration area on the electrode, thereby protecting the stress concentration area, reducing the probability of active material shedding, reducing the probability of lithium plating on the electrode, and improving the working reliability of the battery cell.

[0004] To achieve this objective, the present invention adopts the following technical solution: A battery cell is formed by winding an electrode and a separator along a first direction. The electrode includes a body layer and an active material layer coated on at least one surface of the body layer. The battery cell includes a stress concentration region and a flat region. The stress concentration region is formed by bending the electrode. Adhesive tape is adhered to the surface of the electrode, and at least a portion of the adhesive tape is disposed in the stress concentration region. In a second direction, at least one end of the tape extends beyond the electrode. The tape includes a substrate layer and an adhesive layer. The substrate layer includes a non-adhesive region extending beyond the adhesive layer. The substrate layer also includes an inactive material region. The adhesive layer at least partially overlaps with the inactive material region. The peel force between the adhesive layer and the electrode is F. The area of ​​the non-adhesive region is A, which is the ratio of the area of ​​the substrate layer to the area of ​​the non-adhesive region. In the second direction, the height of the tape extending beyond the electrode is d. F, A, and d satisfy the relationship: 0.4 × 10⁻⁶. -2 -≤(F×A) / d≤241.7×10 -2 .

[0005] A battery includes a housing and a cell as described above, wherein the cell is disposed inside the housing.

[0006] The beneficial effects of the battery cell of this invention are as follows: The applicant's research has found that the greater the peel force between the adhesive layer and the electrode, the better the adhesion between the tape and the electrode; conversely, the smaller the peel force, the worse the adhesion, and the greater the probability of active material falling off from the stress concentration area of ​​the electrode. A larger ratio (A) of the non-adhesive area to the substrate layer area results in worse adhesion between the tape and the electrode, but facilitates ion passage and reduces the risk of lithium plating. A smaller ratio (A) of the non-adhesive area to the substrate layer area results in better adhesion, but a longer ion transport distance and a higher risk of lithium plating. A larger height (d) of the tape extending beyond the electrode results in better adhesion, and a smaller height (d) results in worse adhesion. Limiting only one of the three parameters F, A, and d only guarantees the adhesion between the electrode and the tape or reduces the risk of lithium plating. In the embodiments disclosed in this invention, the formula (F×A) / d is used. If the value of the formula is too large, the risk of lithium plating on the electrode is high; if the value of the formula is too small, the adhesion between the tape and the electrode is worse, and the probability of active material falling off from the stress concentration area of ​​the electrode is greater. Therefore, (F×A) / d is controlled at 0.4×10⁻⁶. -2 -241.7×10 -2 Within a certain range, this ensures that the tape adheres stably to the stress concentration area on the electrode, protecting this area, reducing the likelihood of active material detachment, decreasing the probability of lithium plating on the electrode, and improving the cell's operational reliability. Meanwhile, the inactive material area on the electrode is either the tab adhesive or the foil constituting the electrode body layer. Compared to the active material, the adhesive layer has better adhesion to the inactive material area. Since the adhesive layer and the inactive material area at least partially overlap, the adhesion strength between the tape and the electrode is further enhanced.

[0007] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0008] Figure 1 This is a schematic diagram of the battery cell structure according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the first mating structure of the electrode sheet and the tape according to an embodiment of the present invention; Figure 3 yes Figure 2 Schematic diagram of the structure of the medium-density adhesive tape; Figure 4 This is a schematic diagram of a second mating structure between the electrode sheet and the tape according to an embodiment of the present invention; Figure 5 yes Figure 4 Schematic diagram of the structure of the medium-density adhesive tape; Figure 6 This is a schematic diagram of the third mating structure of the electrode sheet and tape according to an embodiment of the present invention; Figure 7 yes Figure 6 A schematic diagram of the structure of the medium-density adhesive tape.

[0009] Figure 8 This is a schematic diagram of the battery structure according to an embodiment of the present invention.

[0010] Figure label: 10. Separator; 20. Electrode; 21. Positive electrode; 22. Negative electrode; 201. Inactive material area; 30. Adhesive tape; 31. Substrate layer; 311. Non-adhesive area; 32. Adhesive layer; 40. Stress concentration area; 50. Flat area; 60. Shell; 61. Injection hole. Detailed Implementation

[0011] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0012] In the description of this invention, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0013] In the description of this embodiment, the terms "upper," "lower," "left," "right," "front," and "rear," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention. Furthermore, the terms "first" and "second" are used only for distinction in description and have no special meaning.

[0014] First, it should be noted that, according to the applicant's research, there are gaps between the adhesive layer of the tape and the active material of the electrode. Electrolyte can easily seep in from the gaps at the ends of the protective tape, causing the adhesive layer to swell and the tape's adhesiveness to decrease. This leads to the protective tape falling off and failing to protect the electrode. However, if the adhesion is increased to ensure a strong connection between the tape and the electrode, a larger tape size would lengthen the ion transport path, increasing the risk of lithium plating on the electrode.

[0015] This invention discloses a battery cell, with reference to Figures 1-2 As shown, the battery cell is formed by winding the electrode 20 and the separator 10 along a first direction, which is the winding direction of the electrode 20 and the length direction of the electrode 10 after it is unfolded. The electrode 20 includes a body layer and an active material layer coated on at least one surface of the body layer. The body layer also includes an inactive material region 201. The active material layer and the inactive material region 201 are arranged along a second direction. During the manufacturing process, the separator 10 is sandwiched between the positive electrode 21 and the negative electrode 22. The core of the winding process is to stack these three layers of materials like paper and roll them into a cylindrical or square battery cell, and then inject electrolyte and encapsulate it.

[0016] The positive electrode 21 is one of the core components in the battery cell that carries the positive electrode active material. During charging, metal ions (e.g., lithium ions) are extracted from the crystal lattice of the active material layer of the positive electrode 21 (oxidation reaction), migrate through the electrolyte, and embed into the negative electrode 22. During discharging, metal ions (e.g., lithium ions in a lithium battery) are extracted from the negative electrode 22 and embed into the crystal lattice of the positive electrode active material (reduction reaction), realizing the storage and release of lithium ions. The positive electrode 21 generally includes a positive electrode current collector and a positive electrode active material layer. The positive electrode active material layer is coated on at least one surface of the positive electrode current collector and includes: positive electrode active material, conductive agent, and binder. The positive electrode active material includes, but is not limited to, at least one of the following materials: lithium phosphate, lithium transition metal oxide and their respective modified compounds, or other conventional materials that can be used as positive electrode active materials in batteries. These positive electrode active materials can be used alone or in combination of two or more. Among them, lithium phosphates include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also abbreviated as LFP)), lithium iron phosphate and carbon composites, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate and carbon composites, lithium iron manganese phosphate, and lithium iron manganese phosphate and carbon composites. Lithium transition metal oxides include, but are not limited to, lithium cobalt oxides (such as LiCoO2), lithium nickel oxides (such as LiNiO2), lithium manganese oxides (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxides, lithium manganese cobalt oxides, lithium nickel manganese oxides, and lithium nickel cobalt manganese oxides (such as LiNi). 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also known as NCM333), LiNi 0.5 Co 0.2 Mn 0.3 O2 (also known as NCM523), LiNi 0.5 Co0.25 Mn 0.25 O2 (also known as NCM211), LiNi 0.6 Co 0.2 Mn 0.2 O2 (also known as NCM622), LiNi 0.8 Co 0.1 Mn 0.1 O2 (also known as NCM811), lithium nickel cobalt aluminum oxide (such as LiNi) 0.85 Co 0.15 Al 0.05 At least one of O2 and its modified compounds. Conductive agents include, but are not limited to, one or more combinations of graphite, superconducting carbon, carbon black (such as acetylene black, Ketjen black, Super P, etc.), carbon nanotubes, graphene, and carbon nanofibers. Positive electrode binders include, but are not limited to, one or more combinations of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, fluorinated acrylate resins, styrene-butadiene rubber, polyacrylic acid, sodium polyacrylate, polyacrylamide, polyvinyl alcohol, sodium alginate, polymethacrylic acid, and carboxymethyl chitosan.

[0017] The negative electrode 22 is one of the core components in the battery cell that carries the negative electrode active material. During battery charging, active ions (such as lithium ions) from the positive electrode 21 are embedded in the negative electrode 22, while electrons from the positive electrode are transferred to the negative electrode 22 through an external circuit, maintaining charge balance. During discharge, active ions (such as Li) previously embedded in the negative electrode 22 can be released, while electrons from the negative electrode 22 are transferred to the negative electrode through an external circuit, maintaining charge balance; thus achieving energy storage and release. The negative electrode 22 includes a negative electrode current collector and a negative electrode active layer disposed on at least one surface of the negative electrode current collector. The negative electrode current collector is a conductive metal foil, which can be made of stainless steel, copper, aluminum, nickel, carbon electrode, or titanium with a silver-plated surface. Composite current collectors may include a polymer material base layer and a metal layer. Composite current collectors can be formed by depositing metallic materials (aluminum, aluminum alloys, copper, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys, etc.) onto a polymer substrate (such as polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.). The negative electrode active layer includes the negative electrode active material, conductive agent, and binder. The negative electrode active material can be carbon-based materials such as graphite, porous carbon, hard carbon, soft carbon, and mesophase carbon microspheres, or silicon-based materials such as elemental silicon, silicon oxides, silicon-carbon composites, and silicon-nitrogen composites. The conductive agent can be conductive carbon black, carbon nanotubes, etc., and the binder can be styrene-butadiene rubber, polyacrylic acid, etc.

[0018] A separator 10 is disposed between the positive electrode 21 and the negative electrode 22 to separate them and prevent short circuits. It can be at least one of glass fiber, non-woven fabric, polyethylene (PE), polypropylene (PP), and polyvinylidene fluoride. A coating can also be provided on the surface of the separator 10. The coating can be an inorganic coating and, or an organic coating, wherein the inorganic coating material includes at least one of alumina, silicon oxide, titanium oxide, magnesium oxide, zirconium oxide, and boehmite; and the organic coating includes at least one of aramid coating and polyvinylidene fluoride (PVDF) coating.

[0019] The inactive material region 201 is coated on at least one side of the current collector near the tab, or on at least one side of the tab 202 surface, to prevent short circuits between the tab and the opposite electrode, and also to prevent the tab 202 from breaking easily when bent during assembly. The tab insulating layer mainly includes insulating materials such as PVDF (polyvinylidene fluoride), boehmite, polypropylene, and polyethylene.

[0020] Before winding, the positive electrode 21 and negative electrode 22 need to be laser-cut or die-cut into a fixed shape (e.g., rectangular), with smooth, burr-free edges; otherwise, they may puncture the separator 10, causing a short circuit. The separator 10 is cut into strips slightly wider than the positive and negative electrode 21 and 22 to ensure complete wrapping during winding. After winding, the cell is cylindrical (for cylindrical batteries such as 18650 and 21700) or elliptical or racetrack-shaped (formed by subsequent flattening for prismatic batteries). This invention pertains to cells used in prismatic batteries. (Continue to the previous section.) Figures 1-7 As shown, the wound battery cell includes a stress concentration region 40 and a flat region 50. The stress concentration region 40 is formed by bending an electrode 20. An adhesive tape 30 is bonded to the surface of the electrode 20, with at least a portion of the tape 30 located in the stress concentration region 40. In a second direction, at least one end of the tape 30 extends beyond the electrode 20. The tape 30 includes a substrate layer 31 and an adhesive layer 32. The substrate layer 31 includes a non-adhesive region 311 extending beyond the adhesive layer 32. The adhesive layer 32 at least partially overlaps with the inactive material region 201. The peel force between the adhesive layer 32 and the electrode 20 is FN / cm. The area of ​​the non-adhesive region 311 is A, which represents the area of ​​the substrate layer 31. In the second direction, the height of the tape 30 extending beyond the electrode 20 is dmm. F, A, and d satisfy the relationship: 0.4 × 10⁻⁶. -2 ≤(F×A) / d≤241.7×10 -2 Specifically, it is 0.4 × 10 -2 1×10 -2 5×10 -2 10×10 -2 20×10 -2 30×10 -240×10 -2 50×10 -2 60×10 -2 70×10 -2 80×10 -2 90×10 -2 100×10 -2 120×10 -2 130×10 -2 140×10 -2 150×10 -2 160×10 -2 170×10 -2 180×10 -2 190×10 -2 200×10 -2 220×10 -2 230×10 -2 240×10 -2 241.7×10 -2 Of course, you can also choose 0.4×10 according to actual needs. -2 -241.7×10 -2 Other values ​​within the range are not limited to those listed above. It is understandable that, through the applicant's research, it has been found that the greater the peel force between the adhesive layer 32 and the electrode 20, the better the adhesion between the tape 30 and the electrode 20; conversely, the smaller the peel force, the worse the adhesion. This also increases the likelihood of active material falling off from the stress concentration area 40 of the electrode 20. Furthermore, the larger the proportion A of the non-adhesive area 311 to the area of ​​the substrate layer 31, the worse the adhesion between the tape 30 and the electrode 20, but this facilitates ion passage and reduces... Lowering the risk of lithium plating increases the likelihood of active material falling off from the stress concentration area 40 of the electrode 20. A smaller ratio (A) of the non-adhesive region 311 to the substrate layer 31 results in better adhesion between the tape 30 and the electrode 20, but also a longer ion transport distance and a higher risk of lithium plating. A larger height (d) of the tape 30 extending beyond the electrode 20 results in better adhesion, while a smaller height (d) results in poorer adhesion. Limiting only one of the three parameters (F, A, d) either guarantees only the adhesion between the electrode 20 and the tape 30, or only reduces the risk of lithium plating. In the embodiments disclosed in this invention, the formula (F×A) / d is used. If the value of the formula is too large, the risk of lithium plating on the electrode 20 is high; if the value of the formula is too small, the adhesion between the tape 30 and the electrode 20 will be poor, and the probability of active material falling off from the stress concentration area 40 of the electrode 20 will be greater. Therefore, (F×A) / d is controlled at 0.4×10. -2 -241.7×10 -2Within the specified range, the tape 30 can be stably bonded to the stress concentration area 40 on the electrode 20, thus protecting the stress concentration area 40, reducing the probability of active material detachment, reducing the probability of lithium plating on the electrode 20, and improving the operational reliability of the battery cell. Meanwhile, the inactive material area 201 on the electrode 20 may be tab adhesive or foil constituting the body layer of the electrode 20. Compared to the active material, the adhesive layer 32 has better adhesion to the inactive material area 201. Since the adhesive layer 32 and the inactive material area 201 at least partially overlap, the bonding strength between the tape 30 and the electrode 20 is further improved.

[0021] It should be noted that the peel force of tape 30 can be measured using GB / T 2792-2014. The peel force F of tape 30 can be adjusted by modifying the thickness of the adhesive layer 32, the proportion of adhesive in the adhesive layer 32, the area ratio and location of the non-adhesive area 311, the material of the adhesive layer 32, and whether or not to include through-holes in the tape 30.

[0022] Optionally, the substrate layer 31 of the tape 30 may be made of at least one of the following: polyvinyl chloride, polyethylene, polypropylene, polyvinylidene fluoride, hexafluoropropylene-vinylidene fluoride copolymer, tetrafluoropropylene-vinylidene fluoride copolymer, trifluorochloropropylene-vinylidene fluoride copolymer, polyethylene terephthalate, polyimide, polyetherimide, polycarbonate, polystyrene, polyphenylene sulfide, polyvinylidene fluoride, polyvinylidene fluoride copolymer, polyarylate, fiber, nylon, nonwoven fabric, etc.

[0023] Optionally, the adhesive layer 32 of tape 30 may be made of at least one of the following: acrylic-acrylate copolymer, butadiene-styrene copolymer, styrene-acrylic copolymer, styrene-acrylate copolymer, ethylene-vinyl acetate copolymer, acrylic-grafted polyethylene, maleic anhydride-grafted polyethylene, acrylic-grafted polypropylene, polyvinylidene fluoride, maleic anhydride-grafted polypropylene, carboxymethyl cellulose, polyimide, polyetherimide, styrene-isoprene-styrene copolymer rubber, polyethylene phthalate, ethylene-vinyl acetate copolymer bisphenol A type epoxy resin, ethylene-vinyl acetate copolymer bisphenol F type epoxy resin, glycerol ether type epoxy resin, glycerol ester type epoxy resin, silicone type resin, polyurethane, styrene-isoprene-styrene copolymer, etc.

[0024] Optionally, along the second direction, the tape 30 extends beyond one end of the electrode 20 by a distance d1, where d1 satisfies the relationship: 0.1mm ≤ d1mm ≤ 5mm. Specifically, the distance d1 of the tape 30 extending beyond the electrode 20 can be 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm, 2mm, 2.1mm, 2.2mm, 2.3mm, 2.4mm, 2.5mm, 2.6mm, 2. The thicknesses are 7mm, 2.8mm, 2.9mm, 3mm, 3.1mm, 3.2mm, 3.3mm, 3.4mm, 3.5mm, 3.6mm, 3.7mm, 3.8mm, 3.9mm, 4mm, 4.1mm, 4.2mm, 4.3mm, 4.4mm, 4.5mm, 4.6mm, 4.7mm, 4.8mm, 4.9mm, and 5mm. Of course, other values ​​within the range of 0.1mm to 5mm can also be selected according to actual needs, and are not limited to the examples listed above. It is understandable that, along the second direction, the extension of the tape 30 beyond the end of the electrode 20 is beneficial to improving the bonding stability between the tape 30 and the electrode 20. If the extension distance is too small, the improvement in bonding stability is not significant, and if the extension distance is too large, the tape 30 and the electrode 20 are prone to separation. In this embodiment, setting the distance of the tape 30 extending beyond the end of the electrode 20 within the range of 0.1mm-5mm can ensure the bonding stability between the tape 30 and the electrode 20.

[0025] Optionally, along the second direction, both ends of the tape 30 extend beyond the end of the electrode 20 by distances d1 and d2, respectively, where d1 and d2 satisfy the relationship: 1mm ≤ d1mm + d2mm ≤ 10mm. Specifically, the values ​​of d1 + d2 can be 1mm, 1.5mm, 2mm, 2.5mm, 3mm, 3.5mm, 4mm, 4.5mm, 5mm, 5.5mm, 6mm, 6.5mm, 7mm, 7.5mm, 8mm, 8.5mm, 9mm, 9.5mm, or 10mm, or other values ​​within the range of 1mm to 10mm can be selected according to actual needs, and are not limited to the examples mentioned above. It is understandable that, along the second direction, the extension of the tape 30 beyond the electrode 20 helps improve the bonding stability between the tape 30 and the electrode 20. If the extension distance is too small, the improvement in bonding stability is not significant; if the extension distance is too large, the tape 30 and the electrode 20 are prone to separation. In this embodiment, setting the sum of the distances d1 and d2 of the tape 30 extending beyond the electrode 20 to the range of 1mm-10mm ensures the bonding stability between the tape 30 and the electrode 20. Compared to extending beyond the electrode 20 at one end, extending beyond the electrode 20 at both ends better improves the bonding stability between the tape 30 and the electrode 20.

[0026] Optionally, in the second direction, at least one end of the tape 30 extends beyond the diaphragm 10 by a total distance d3, where d3 satisfies the relationship: 0.5mm ≤ d3mm ≤ 10mm. Specifically, the value of d3 can be 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm, 2mm, 2.1mm, 2.2mm, 2.3mm, 2.4mm, 2.5mm, 2.6mm, 2.7mm, or 2.8mm. m, 2.9mm, 3mm, 3.1mm, 3.2mm, 3.3mm, 3.4mm, 3.5mm, 3.6mm, 3.7mm, 3.8mm, 3.9mm, 4mm, 4.1mm, 4 .2mm, 4.3mm, 4.4mm, 4.5mm, 4.6mm, 4.7mm, 4.8mm, 4.9mm, 5mm, 5mm, 5.1mm, 5.2mm, 5.3mm, 5.4m m, 5.5mm, 5.6mm, 5.7mm, 5.8mm, 5.9mm, 6mm, 6.1mm, 6.2mm, 6.3mm, 6.4mm, 6.5mm, 6.6mm, 6.7mm , 6.8mm, 6.9mm, 7mm, 7.1mm, 7.2mm, 7.3mm, 7.4mm, 7.5mm, 7.6mm, 7.7mm, 7.8mm, 7.9mm, 8mm, 8. The thickness of the adhesive tape 30 can be 1mm, 8.2mm, 8.3mm, 8.4mm, 8.5mm, 8.6mm, 8.7mm, 8.8mm, 8.9mm, 9mm, 9.1mm, 9.2mm, 9.3mm, 9.4mm, 9.5mm, 9.6mm, 9.7mm, 9.8mm, 9.9mm, or 10mm. Other values ​​within the range of 0.5mm to 10mm can also be selected according to actual needs, and are not limited to the examples listed above. It is understood that during the manufacturing process, the dimension of the diaphragm 10 along the second direction is usually larger than that of the electrode 20. At least one end of the adhesive tape 30 extends beyond the diaphragm 10. In the actual bonding process, the adhesive tape 30 can not only bond to the electrode 20 but also to the diaphragm 10, maximizing the connection strength between the adhesive tape 30 and the electrode 20, reducing the probability of the adhesive tape 30 detaching, and thus reducing the probability of active material falling off.It should be further noted that if the distance of the tape 30 extending beyond the diaphragm 10 is too small, the improvement in adhesion stability is not significant. If the distance of the tape 30 extending beyond the diaphragm 10 is too large, the contact area between the tape 30 and the electrolyte will increase during the electrolyte injection process, which will increase the risk of the tape 30 falling off. In this embodiment, the distance d3 of the end of the tape 30 extending beyond the diaphragm 10 is controlled between 0.5mm and 10mm, which can ensure the connection stability between the tape 30 and the electrode 20, reduce the probability of the tape 30 falling off, and thus reduce the probability of the active material falling off.

[0027] Optionally, the current collector of the electrode 20 includes an aluminum layer. Along the first direction, the size of the single-piece adhesive tape 30 is L1mm, where L1 satisfies the relationship: 10mm≤L1mm≤30mm. Specifically, the size L1 of the single-piece adhesive tape 30 can be selected from 10mm, 11mm, 12mm, 13mm, 14mm, 15mm, 16mm, 17mm, 18mm, 19mm, 20mm, 21mm, 22mm, 23mm, 24mm, 25mm, 26mm, 27mm, 28mm, 29mm, and 30mm. Of course, other values ​​within the range of 10mm-30mm can also be selected, and it is not limited to the examples mentioned above. Understandably, as mentioned above, the positive electrode 21 is typically made of aluminum foil coated with active materials such as lithium cobalt oxide, ternary lithium, or lithium iron phosphate, while the negative electrode 22 is made of copper foil coated with graphite or silicon carbide. Compared to copper foil, the positive electrode 21 with an aluminum layer is more prone to tearing during winding. If the size of the tape 30 along the first direction is too small, the probability of the positive electrode 21 tearing will increase. If the size of the tape 30 along the first direction is too large, it will increase the ion transport distance and increase the probability of lithium plating. In this embodiment, the size of the tape 30 attached to the positive electrode 21 along the first direction is controlled within the range of 10mm-30mm, which can both provide better protection for the positive electrode 21 and control the ion transport distance, thereby reducing the probability of lithium plating.

[0028] Optionally, the ratio A of the area of ​​the non-adhesive region 311 to the area of ​​the substrate layer 31 can range from 0.05 to 0.5. Specifically, the ratio A of the area of ​​the non-adhesive region 311 to the area of ​​the substrate layer 31 can be 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, or other values ​​within the range of 0.05 to 0.5, and is not limited to the examples mentioned above. It is understood that within the aforementioned formula range, a larger ratio A of the area of ​​the non-adhesive region 311 to the area of ​​the substrate layer 31 will, to some extent, result in lower adhesive strength, while a smaller ratio A of the area of ​​the non-adhesive region 311 to the area of ​​the substrate layer 31 will, to some extent, increase the risk of lithium plating. In this embodiment, within the aforementioned formula range, further controlling the ratio A of the area of ​​the non-adhesive region 311 to the area of ​​the substrate layer 31 within the range of 0.05 to 0.5 can better balance the effects of adhesive strength and reducing the risk of lithium plating.

[0029] Optionally, the peel force FN / cm between the adhesive layer 32 and the electrode 20 can range from 0.6 N / cm to 3.0 N / cm. Specifically, the peel force F between the adhesive layer 32 and the electrode 20 can be 0.6 N / cm, 0.7 N / cm, 0.8 N / cm, 0.9 N / cm, 1 N / cm, 1.1 N / cm, 1.2 N / cm, 1.3 N / cm, 1.4 N / cm, 1.5 N / cm, or 1.6 N / cm. The values ​​are 1.7 N / cm, 1.8 N / cm, 1.9 N / cm, 2 N / cm, 2.1 N / cm, 2.2 N / cm, 2.3 N / cm, 2.4 N / cm, 2.5 N / cm, 2.6 N / cm, 2.7 N / cm, 2.8 N / cm, 2.9 N / cm, and 3 N / cm. Other values ​​within the range of 0.6 N / cm to 3.0 N / cm can also be selected, and the examples are not limited to those listed above. It is understood that within the aforementioned formula range, a lower peel force F between the non-adhesive layer 32 and the electrode 20 will result in lower adhesive strength to some extent, while a higher peel force F between the adhesive layer 32 and the electrode 20 places higher demands on the adhesive layer 32, increasing the cost of the tape 30. In this embodiment, within the aforementioned formula range, the peel force F between the adhesive layer 32 and the electrode 20 is controlled within the range of 0.6 N / cm to better balance adhesive strength and cost control.

[0030] Optionally, in the second direction, the value of the total height dmm of the tape 30 exceeding the electrode 20 is in the range of 0.5mm-10mm. Specifically, the specific value of d can be 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm, 2mm, 2.1mm, 2.2mm, 2.3mm, 2.4mm, 2.5mm, 2.6mm, 2.7mm, or 2.8mm. , 2.9mm, 3mm, 3.1mm, 3.2mm, 3.3mm, 3.4mm, 3.5mm, 3.6mm, 3.7mm, 3.8mm, 3.9mm, 4mm, 4.1mm, 4. 2mm, 4.3mm, 4.4mm, 4.5mm, 4.6mm, 4.7mm, 4.8mm, 4.9mm, 5mm, 5mm, 5.1mm, 5.2mm, 5.3mm, 5.4mm , 5.5mm, 5.6mm, 5.7mm, 5.8mm, 5.9mm, 6mm, 6.1mm, 6.2mm, 6.3mm, 6.4mm, 6.5mm, 6.6mm, 6.7mm , 6.8mm, 6.9mm, 7mm, 7.1mm, 7.2mm, 7.3mm, 7.4mm, 7.5mm, 7.6mm, 7.7mm, 7.8mm, 7.9mm, 8mm, 8. The possible values ​​are 1mm, 8.2mm, 8.3mm, 8.4mm, 8.5mm, 8.6mm, 8.7mm, 8.8mm, 8.9mm, 9mm, 9.1mm, 9.2mm, 9.3mm, 9.4mm, 9.5mm, 9.6mm, 9.7mm, 9.8mm, 9.9mm, and 10mm. Other values ​​within the range of 0.5mm to 10mm can also be selected based on actual needs, and are not limited to the examples listed above. It is understood that, along the second direction, the extension of the tape 30 beyond the end of the electrode 20 is beneficial for improving the bonding stability between the tape 30 and the electrode 20. If the extension distance is too small, the improvement in bonding stability is not significant; if the extension distance is too large, the tape 30 and the electrode 20 are prone to separation. In this embodiment, setting the distance of the tape 30 extending beyond the end of the electrode 20 within the range of 0.1mm to 5mm ensures the bonding stability between the tape 30 and the electrode 20.

[0031] Optional, see reference Figure 3 As shown, along the first direction, a non-adhesive region 311 is disposed at at least one end of the tape 30. It can be understood that by disposing the non-adhesive region 311 at at least one end of the tape 30, the ion transport distance can be shortened as much as possible while ensuring the connection stability between the tape 30 and the electrode 20, thereby reducing the probability of lithium plating.

[0032] Alternatively, the size of the non-adhesive area 311 is L2, where L2 satisfies the relationship: 1mm≤L2mm≤10mm. Specifically, the dimension L2 of the non-adhesive area 311 can be 1mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm, 2mm, 2.1mm, 2.2mm, 2.3mm, 2.4mm, 2.5mm, 2.6mm, 2.7mm, 2.8mm, 2.9mm, 3mm, 3.1mm, 3.2mm, 3.3mm, 3.4mm, 3.5mm, 3.6mm, 3.7mm, 3.8mm, 3.9mm, 4mm, 4.1mm, 4.2mm, 4.3mm, 4.4mm, 4.5mm, 4.6mm, 4.7mm, 4.8mm, 4.9mm, 5mm, 5.1mm, 5.2mm, 5.3mm, 5.4mm, 5.5mm, 5mm. The thicknesses are 6mm, 5.7mm, 5.8mm, 5.9mm, 6mm, 6.1mm, 6.2mm, 6.3mm, 6.4mm, 6.5mm, 6.6mm, 6.7mm, 6.8mm, 6.9mm, 7mm, 7.1mm, 7.2mm, 7.3mm, 7.4mm, 7.5mm, 7.6mm, 7.7mm, 7.8mm, 7.9mm, 8mm, 8.1mm, 8.2mm, 8.3mm, 8.4mm, 8.5mm, 8.6mm, 8.7mm, 8.8mm, 8.9mm, 9mm, 9.1mm, 9.2mm, 9.3mm, 9.4mm, 9.5mm, 9.6mm, 9.7mm, 9.8mm, 9.9mm, and 10mm. Of course, other values ​​within the range of 1mm to 10mm are also possible and are not limited to the examples listed above. It is understandable that an excessively large size of the non-adhesive region 311 would result in an excessively small size of the adhesive layer 32, thereby reducing the connection strength between the tape 30 and the electrode 20. Conversely, an excessively small size of the non-adhesive region 311 would result in an excessively large size of the adhesive layer 32, extending the ion transport distance and increasing the risk of lithium plating. In this embodiment, the size of the non-adhesive region 311 along the first direction is controlled within the range of 1mm-10mm. This ensures the connection strength between the tape 30 and the electrode 20 while avoiding an excessively long ion transport distance and reducing the risk of lithium plating. It should be further noted that if the non-adhesive region 311 is only located at one end of the tape 30 along the first direction, then L2 is the size of the non-adhesive region 311. If the non-adhesive region 311 is located at both ends of the tape 30 along the first direction, then L2 is the sum of the sizes of the two non-adhesive regions 311.

[0033] Optionally, along the first direction, non-adhesive areas 311 are disposed at both ends of the adhesive tape 30, and the peel force FN / cm between the adhesive layer 32 and the electrode 20 ranges from 0.8 N / cm to 3.0 N / cm. Specifically, the peel force FN between the adhesive layer 32 and the electrode 20 can be 0.8 N / cm, 0.9 N / cm, 1 N / cm, 1.1 N / cm, 1.2 N / cm, 1.3 N / cm, 1.4 N / cm, or 1.5 N / cm. The values ​​are 1.6 N / cm, 1.7 N / cm, 1.8 N / cm, 1.9 N / cm, 2 N / cm, 2.1 N / cm, 2.2 N / cm, 2.3 N / cm, 2.4 N / cm, 2.5 N / cm, 2.6 N / cm, 2.7 N / cm, 2.8 N / cm, 2.9 N / cm, and 3 N / cm. Of course, other values ​​within the range of 0.8 N / cm to 3.0 N / cm can also be selected, and are not limited to the examples listed above. Understandably, since both ends of the tape 30 are provided with non-adhesive areas 311, the adhesive ability of the tape 30 is weakened to a certain extent. Therefore, the peel force between the adhesive layer 32 and the electrode 20 is limited from the range of 0.6N / cm-3.0N / cm to 0.8N / cm-3.0N / cm, and the lower limit of the peel force F between the adhesive layer 32 and the electrode 20 is increased, thereby improving the bonding strength between the electrode 20 and the tape 30 and reducing the risk of the tape 30 falling off.

[0034] Optional, see reference Figures 4-5 As shown, along the second direction, the non-adhesive region 311 and the end of the electrode 20 are spaced apart. It can be understood that, as mentioned above, the adhesive layer 32 has better adhesion to the inactive material region 201. The end of the electrode 20 along the second direction is typically the inactive material region 201. The end of the non-adhesive region 311 along the second direction and the end of the electrode 20 along the second direction are spaced apart. After bonding, the adhesive layer 32 is located in the middle of the electrode 20, which not only protects the stress concentration region 40 but also lengthens the ion transport path, reducing the probability of lithium plating on the electrode 20.

[0035] Alternatively, along the second direction, the distance between the end of the non-adhesive region 311 and the electrode 20 can be in the range of 0.1 mm to 9 mm. Specifically, the distance between the non-adhesive region 311 and the end of the electrode 20 can be 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm, 2mm, 2.1mm, 2.2mm, 2.3mm, 2.4mm, 2.5mm, 2.6mm, 2.7mm, 2.8mm, 2.9mm, 3mm, 3.1mm, 3.2mm, 3.3mm, 3.4mm, 3.5mm, 3.6mm, 3.7mm, 3.8mm, 3.9mm, 4mm, 4.1mm, 4.2mm, 4.3mm, 4.4mm, 4.5mm, or 4.6mm. The thicknesses are 4.7mm, 4.8mm, 4.9mm, 5mm, 5.1mm, 5.2mm, 5.3mm, 5.4mm, 5.5mm, 5.6mm, 5.7mm, 5.8mm, 5.9mm, 6mm, 6.1mm, 6.2mm, 6.3mm, 6.4mm, 6.5mm, 6.6mm, 6.7mm, 6.8mm, 6.9mm, 7mm, 7.1mm, 7.2mm, 7.3mm, 7.4mm, 7.5mm, 7.6mm, 7.7mm, 7.8mm, 7.9mm, 8mm, 8.1mm, 8.2mm, 8.3mm, 8.4mm, 8.5mm, 8.6mm, 8.7mm, 8.8mm, 8.9mm, and 9mm. Of course, other values ​​within the range of 0.1mm to 9mm are also possible, and the values ​​are not limited to those listed above. Understandably, if the ends of the non-adhesive region 311 and the electrode 20 are too small, it indicates that the size of the adhesive layer 32 along the second direction is large. Although this can improve the connection stability between the tape 30 and the electrode 20, it will prolong the ion transport path. If the ends of the non-adhesive region 311 and the electrode 20 are too large, it indicates that the size of the adhesive layer 32 along the second direction is small, which will reduce the connection stability between the tape 30 and the electrode 20. In this embodiment, the distance between the ends of the non-adhesive region 311 and the electrode 20 is 0.1mm-9mm, which can ensure the connection stability between the electrode 20 and the tape 30, and also control the ion transport path so that it is not too long, thus reducing the probability of lithium plating on the electrode 20.

[0036] Further optional, see reference Figures 6-7As shown, along the first direction, the non-adhesive area 311 is spaced apart from the end of the adhesive tape 30. It can be understood that, given the spaced-apart arrangement between the non-adhesive area 311 and the end of the electrode 20 along the second direction, the spaced-apart arrangement between the non-adhesive area 311 and the end of the adhesive tape 30 along the second direction allows the non-adhesive area 311 of the adhesive tape 30 to surround the adhesive layer 32. This arrangement ensures the connection stability between the electrode 20 and the adhesive tape 30 while controlling the ion transport path to prevent it from becoming excessively long.

[0037] Optionally, the distance between the non-adhesive area 311 and the end of the adhesive tape 30 along the first direction can range from 1mm to 14mm. Specifically, the distance between the non-adhesive area 311 and the end of the adhesive tape 30 along the first direction can be 1mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm, 2mm, 2.1mm, 2.2mm, 2.3mm, 2.4mm, 2.5mm, 2.6mm, 2.7mm, 2.8mm, 2.9mm, 3mm, 3.1mm, 3.2mm, 3.3mm, 3.4mm, 3.5mm, 3.6mm, 3.7mm, 3.8mm, 3.9mm, or 4mm. 4.1mm, 4.2mm, 4.3mm, 4.4mm, 4.5mm, 4.6mm, 4.7mm, 4.8mm, 4.9mm, 5mm, 5mm, 5.1mm, 5.2mm, 5.3mm, 5.4mm, 5.5mm, 5.6mm, 5.7mm, 5 .8mm, 5.9mm, 6mm, 6.1mm, 6.2mm, 6.3mm, 6.4mm, 6.5mm, 6.6mm, 6.7mm, 6.8mm, 6.9mm, 7mm, 7.1mm, 7.2mm, 7.3mm, 7.4mm, 7.5mm, 7. 6mm, 7.7mm, 7.8mm, 7.9mm, 8mm, 8.1mm, 8.2mm, 8.3mm, 8.4mm, 8.5mm, 8.6mm, 8.7mm, 8.8mm, 8.9mm, 9mm, 9.1mm, 9.2mm, 9.3mm, 9.4 mm, 9.5mm, 9.6mm, 9.7mm, 9.8mm, 9.9mm, 10mm, 10mm, 10.1mm, 10.2mm, 10.3mm, 10.4mm, 10.5mm, 10.6mm, 10.7mm, 10.8mm, 10.9mm The thicknesses are 11mm, 11.1mm, 11.2mm, 11.3mm, 11.4mm, 11.5mm, 11.6mm, 11.7mm, 11.8mm, 11.9mm, 12mm, 12.1mm, 12.2mm, 12.3mm, 12.4mm, 12.5mm, 12.6mm, 12.7mm, 12.8mm, 12.9mm, 13mm, 13.1mm, 13.2mm, 13.3mm, 13.4mm, 13.5mm, 13.6mm, 13.7mm, 13.8mm, 13.9mm, and 14mm. Of course, other values ​​within the range of 1mm to 14mm are also possible, and the examples are not limited to those listed above.Understandably, if the ends of the non-adhesive region 311 and the electrode 20 are too small, it means that the size of the adhesive layer 32 along the first direction is large. Although this can improve the connection stability between the tape 30 and the electrode 20, it will prolong the ion transport path. If the ends of the non-adhesive region 311 and the electrode 20 are too large, it means that the size of the adhesive layer 32 along the first direction is small, which will reduce the connection stability between the tape 30 and the electrode 20. In this embodiment, the distance between the ends of the non-adhesive region 311 and the electrode 20 is 1mm-14mm. This can ensure the connection stability between the electrode 20 and the tape 30, and also control the ion transport path so that it is not too long, thus reducing the probability of lithium plating on the electrode 20.

[0038] Optionally, through holes are provided on the substrate layer 31. It is understood that, as mentioned above, bonding with the electrode 20 will increase the ion transport path to a certain extent. In this embodiment, providing through holes on the substrate layer 31 can reduce the ion transport path while ensuring the bonding strength between the tape 30 and the electrode 20, thereby reducing the probability of lithium plating on the electrode 20.

[0039] Optionally, at least some of the through-holes are disposed in the non-adhesive region 311. It is understood that, compared to disposing of the through-holes in the adhesive layer 32, disposing of at least some of the through-holes in the non-adhesive region 311 ensures the bonding strength between the tape 30 and the electrode 20 while maintaining the strength of the tape 30, reducing the probability of tape 30 damage, and also reducing the ion transport path to some extent, thereby reducing the probability of lithium plating on the electrode 20.

[0040] Alternatively, the area of ​​a single through-hole can range from 78.5 μm. 2 -196250μm 2 Specifically, it can be 78.5μm. 2 100μm 2 500μm 2 1000μm 2 5000μm 2 10000μm 2 50000μm 2 100000μm 2 196250μm 2 Of course, other values ​​within the range of 78.5 μm² to 196250 μm² can be selected according to actual needs, and are not limited to the examples mentioned above. It is understandable that if the area of ​​a single through-hole is too large, it will reduce the bonding strength between the tape 30 and the electrode 20, reduce the overall strength of the tape 30, and increase the probability of the tape 30 detaching. If the area of ​​a single through-hole is too small, it will increase the ion transport path to some extent. In this embodiment, the area of ​​a single through-hole is controlled at 78.5 μm². 2-196250μm 2 Within the range, it can balance the bonding strength between the tape 30 and the electrode 20 and the bonding area between the tape 30 and the electrode 20, and control the ion transport path to reduce the probability of lithium plating on the electrode 20.

[0041] Optionally, the peel force F1 between the substrate layer 31 and the adhesive layer 32 is greater than the peel force F between the adhesive layer 32 and the electrode 20. A greater peel force between the substrate layer 31 and the adhesive layer 32 can ensure the strength of the entire adhesive layer 32, thereby indirectly ensuring the bonding stability between the tape 30 and the electrode 20.

[0042] Optionally, the thickness of the substrate layer 31 is 10μm-70μm, and the specific thickness of the substrate layer 31 can be 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, 16μm, 17μm, 18μm, 19μm, 20μm, 21μm, 22μm, 23μm, 24μm, 25μm, 26μm, 27μm, 28μm, 29μm, 30μm, 31μm, 32μm, 33μm, 34μm, 35μm, 36μm, 37μm, 38μm, 39μm, or 40μm. The values ​​are 41μm, 42μm, 43μm, 44μm, 45μm, 46μm, 47μm, 48μm, 49μm, 50μm, 51μm, 52μm, 53μm, 54μm, 55μm, 56μm, 57μm, 58μm, 59μm, 60μm, 61μm, 62μm, 63μm, 64μm, 65μm, 66μm, 67μm, 68μm, 69μm, and 70μm. Other values ​​within the range of 10μm-70μm can also be selected according to actual needs, and are not limited to the examples listed above. It is understandable that an excessively thick substrate layer 31 would result in an excessively thick tape 30. While this would provide good protection for the stress concentration area 40, it would also increase the overall thickness of the battery cell, and this increase would be unnecessary, which would be detrimental to improving the energy density of the battery cell. Conversely, an insufficiently thin substrate layer 31 would not adequately protect the stress concentration area 40. In this embodiment, the thickness of the substrate layer 31 is controlled between 10μm and 70μm, which provides good protection for the stress concentration area 40 while also controlling the thickness of the battery cell, thus improving the energy density of the battery cell.

[0043] Optionally, the thickness of the adhesive layer 32 is 10μm-50μm, and the specific thickness of the adhesive layer 32 can be 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, 16μm, 17μm, 18μm, 19μm, 20μm, 21μm, 22μm, 23μm, 24μm, 25μm, 26μm, 27μm, 28μm, 29μm, or 30μm. The values ​​are 31μm, 32μm, 33μm, 34μm, 35μm, 36μm, 37μm, 38μm, 39μm, 40μm, 41μm, 42μm, 43μm, 44μm, 45μm, 46μm, 47μm, 48μm, 49μm, 50μm. Other values ​​in the range of 10μm-50μm can also be selected according to actual needs, and are not limited to the examples listed above. It is understandable that an excessively thick adhesive layer 32 would result in an excessively thick adhesive tape 30. While this would provide good protection for the stress concentration area 40, it would also increase the overall thickness of the battery cell, and this increase would be unnecessary, hindering the improvement of the battery cell's energy density. Conversely, an excessively thin adhesive layer 32 would not adequately protect the stress concentration area 40. In this embodiment, the thickness of the adhesive layer 32 is controlled between 10μm and 50μm, which provides good protection for the stress concentration area 40 while controlling the battery cell's thickness, thus improving the battery cell's energy density. It is also understandable that during the process of injecting liquid into the injection hole 61 after the battery cell is installed in the casing... Optionally, along the first direction, adhesive tape 30 is provided on both sides of the stress concentration area 40 of the battery cell. It can be understood that during the winding process, stress concentration areas 40 are provided on both sides of the battery cell along the first direction, which can play a better protective role for the battery cell.

[0044] Optionally, adhesive tape 30 is provided in the first 10 stress concentration areas 40 starting from the winding start position of the electrode 20. It is understood that during the winding process, the stress concentration areas 40 of the inner ring of the cell winding process are more prone to active material shedding, while the stress concentration areas 40 of the outer ring are relatively more stable. In this embodiment, adhesive tape 30 is provided in the first 10 stress concentration areas 40 starting from the winding start position of the electrode 20, that is, adhesive tape 30 is provided in the first five rings inside the cell winding process. This provides good protection for the cell while controlling the cell thickness, which is beneficial for improving the energy density of the cell.

[0045] Optionally, the upper surface and the lower surface of the electrode 20 along its thickness direction are both disposed on the active material layer, and the upper surface and the lower surface of the electrode 20 are both provided with adhesive tape 30.

[0046] Optionally, along the second direction, the tape 30 extends beyond the active material layer on the electrode 20, and the portions of the tape 30 extending beyond the active material layer are bonded together on the upper and lower surfaces of the electrode 20. It is understood that this bonding of the portions of the tape 30 extending beyond the active material layer on the upper and lower surfaces of the electrode 20 improves the connection stability between the tape 30 and the electrode 20. Furthermore, during electrolyte injection after the battery cell is wound, the bonding of the two tapes 30 together reduces the impact of the electrolyte on the tape 30, thereby further reducing the probability of the tape 30 detaching.

[0047] The present invention also discloses a battery, as shown in the reference. Figure 8 As shown, the battery includes a casing and the aforementioned battery cell, with the battery cell located inside the casing. The battery can store chemical energy and controllably convert it into electrical energy. In recyclable batteries, the active materials can be reactivated by charging after discharge for continued use. The battery includes a casing 60 and the aforementioned battery cell, with the battery cell located inside the casing 60. The casing 60 has an electrolyte injection hole 61, which is positioned opposite to the inactive material area 201. The casing 60 is a component that provides a space to house electrode assemblies and other parts, isolating them from the external environment. The casing 60 generally includes a body with an opening at at least one end and a receiving cavity. The opening of the casing 60 can be closed by a cover plate, sealing and isolating the internal environment of the battery cell from the external environment. The materials of the casing 60 include, but are not limited to, copper, iron, aluminum, stainless steel, aluminum alloy, plastic, and aluminum-plastic film. The electrolyte injection hole 61 is used to add electrolyte into the battery. After electrolyte injection, the electrolyte injection hole 61 is sealed using an electrolyte injection hole 61 sealing assembly. The sealing assembly for the injection port 61 can employ structures such as rubber nails or metal nails. Rubber nails can seal the injection port 61 using an interference fit, while metal nails can seal the injection port 61 using welding or an interference fit. The electrolyte is a liquid electrolyte that transports active ions. It is a liquid material that conducts ions while isolating electrons. The electrolyte is composed of solvents, electrolyte salts, additives, and other chemical substances. Solvents can be carbonates, carboxylic acid esters, or ethers; electrolyte salts can be lithium salts, sodium salts, or zinc salts; and additives can be vinylene carbonate, fluoroethylene carbonate, propylene sulfite, vinyl sulfite, etc.

[0048] It is understandable that, given the peel force between the adhesive layer 32 and the electrode 20 is FN / cm, and the ratio A of the area of ​​the non-adhesive region 311 to the area of ​​the substrate layer 31, in the second direction, the height dmm of the adhesive tape 30 extending beyond the electrode 20, F, A, and d satisfy the relationship: 0.4 × 10⁻⁶. -2 ≤(F×A) / d≤241.7×10 -2 This can reduce the impact of the electrolyte on the tape 30, thereby ensuring the protection of the tape 300 and the bent portion 230 of the electrode 20, which is beneficial to ensuring the reliability of the battery.

[0049] Optionally, at least two cells are used, with F, A, and d, satisfying the relationship: 2.2 × 10⁻⁶. -2 ≤(F×A) / d≤191.7×10 -2 Specifically, it is 2.2 × 10⁻⁶. -2 5×10 -2 10×10 -2 20×10 -2 30×10 -2 40×10 -2 50×10 -2 60×10 -2 70×10 -2 80×10 -2 90×10 -2 100×10 -2 120×10 -2 130×10 -2 140×10 -2 150×10 -2 160×10 -2 170×10 -2 180×10 -2 190×10 -2 191.7×10 -2 Of course, you can also choose 2.2×10 according to your actual needs. -2 -191.7×10 -2 Other values ​​within the range are not limited to those listed above. It is understood that after the battery cells are installed in the casing, there will be mutual forces between the multiple cells, which will affect the state of the stress concentration area 40. In this embodiment, by controlling (F×A) / d to 2.2×10... -2 -191.7×10 -2 Internally, it can ensure the protection of the stress concentration area 40, reduce the probability of active material falling off, reduce the probability of lithium plating on the electrode 20, and improve the working reliability of the cell.

[0050] The following describes the battery manufacturing process: Preparation of positive electrode 21: The prepared positive electrode active material, conductive agent acetylene black, and binder PVDF are mixed, and solvent NMP is added. The mixture is stirred under vacuum until the system is homogeneous to obtain a positive electrode slurry. The positive electrode slurry is uniformly coated on both surfaces of the positive electrode current collector aluminum foil, air-dried at room temperature, and then transferred to an oven for further drying. After cold pressing and slitting, positive electrode sheet 21 is obtained. Specifically, the mass ratio of positive electrode active material: conductive agent: binder satisfies (92-98):(4-1):(4-1).

[0051] Preparation of negative electrode 22: The negative electrode active material, conductive agent acetylene black, thickener CMC, and binder SBR are mixed, and deionized water is added as a solvent. The mixture is stirred under vacuum until the system is homogeneous to obtain a negative electrode slurry. The negative electrode slurry is uniformly coated on both surfaces of the negative electrode current collector copper foil, air-dried at room temperature, and then transferred to an oven for further drying. After cold pressing and slitting, negative electrode sheet 22 is obtained. The ratio of negative electrode active material: conductive agent: thickener: binder satisfies (90-96): (4-2): (2-1): (4-1).

[0052] Electrolyte preparation: Ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) were mixed in a volume ratio of 1:1:1 to obtain an organic solvent. Then, fully dried lithium salt LiPF6 was dissolved in the mixed organic solvent to prepare an electrolyte with a concentration of 1 mol / L.

[0053] Preparation of diaphragm 10: Polyethylene film is selected as the diaphragm 10.

[0054] Battery manufacturing: The positive electrode 21, separator 10, and negative electrode 22 are stacked in sequence and wound to form a battery cell. Adhesive tape 30 is attached to the bent portion 230 of the electrode 20 of the battery cell. The battery cell is placed in a housing 60, which is a square shell. The battery is dried, injected with electrolyte, and then packaged, left to stand, formed, and volume-adjusted to obtain a lithium-ion battery.

[0055] The positive electrode active material can be selected from one or more lithium-containing positive electrode active materials, including lithium iron phosphate, ternary materials containing nickel, cobalt, and manganese, and lithium manganese iron phosphate; the negative electrode active material can be selected from one or more negative electrode active main materials, such as artificial graphite, natural graphite, silicon carbide, silicon oxide, and lithium titanate.

[0056] Test Method 1: Battery Capacity Retention Rate Following the battery preparation method described above, corresponding batteries were prepared for each embodiment and comparative example. The parameters of the tape 30 and the battery cell in the batteries obtained in each embodiment and comparative example are shown in Table 1. All other structures are the same. The battery was charged at room temperature (25°C) with a constant current of 0.33C to the upper limit voltage, and then charged with a constant voltage of 0.33C until the current dropped to 0.05C. After standing for 5 minutes, the battery was discharged with a constant current of 0.33C to the lower limit voltage. This process was repeated three times to obtain the third discharge capacity Q1, which was taken as the fixed capacity.

[0057] The battery is charged at room temperature (25℃) with a constant current of 0.33C to the upper limit voltage, then charged with a constant voltage of 0.33C until the current drops to 0.05C. After resting for 5 minutes, the battery is discharged with a constant current of 0.33C to the lower limit voltage. This constitutes one cycle. After n cycles, the discharge capacity Qn of the battery on the nth cycle is recorded. The battery capacity retention rate is calculated using the formula "Battery capacity retention rate = Qn / Q1 × 100%". The number of cycles n when the capacity retention rate first falls below 80% is recorded as the number of cycles for that battery. If n is less than 1200, the battery is considered unqualified; if n is greater than or equal to 1200 and less than 1400, the battery is considered qualified; and if n is greater than or equal to 1400, the battery is considered good.

[0058] When the positive electrode active material of the battery is a nickel-cobalt-manganese ternary cathode, the upper limit voltage is 4.25V and the lower limit voltage is 2.5V. When the positive electrode active material of the battery is lithium iron phosphate, the upper limit voltage is 3.6V and the lower limit voltage is 2.5V.

[0059] In this test, the active material for the positive electrode of the battery was selected from a nickel-cobalt-manganese ternary lithium-ion battery, LiNi0.6Co. 0.2 Mn 0.2 Taking O2 as an example, the mass ratio of positive electrode active material: conductive agent: binder meets 96:2:2; the negative electrode active material is selected from artificial graphite, and the ratio of negative electrode active material: conductive agent: thickener: binder meets 95:2:1:2.

[0060] Test Method 2: Lithium Plating in the Battery Following the battery preparation method described above, corresponding batteries were prepared for each embodiment and comparative example. The parameters of the tape 30 and the battery cell in the batteries obtained in each embodiment and comparative example are shown in Table 1. All other structures are identical. The battery was charged at room temperature (25°C) with a constant current of 0.33C to the upper limit voltage, then charged at a constant voltage until the current dropped to 0.05C. After standing for 5 minutes, the battery was discharged with a constant current of 0.33C to the lower limit voltage. This constituted one cycle, and 2000 cycles were performed. Then, the battery was charged at 0.33C to the upper limit voltage, with a cutoff current less than or equal to 0.05C, resulting in a fully charged battery.

[0061] Disassemble the battery, then remove the electrode 20 and observe the lithium plating on the surface of the negative electrode 22 in the bent portion 230. The part where the projection of a single tape 30 overlaps with the negative electrode 22 is the first region. The lithium plating area of ​​the first region is measured and recorded as S1, and the area of ​​the first region is recorded as S2. According to the formula, the percentage of the lithium plating area on the surface of the bent portion 230 of the negative electrode 22 = (S1 / S2) × 100%, the percentage of the lithium plating area on the surface of the bent portion 230 of the negative electrode 22 is calculated. If the lithium plating area on the surface of the bent portion 230 of the negative electrode 22 is less than 10%, it is considered as no / slight lithium plating; if the lithium plating area on the surface of the bent portion 230 of the negative electrode 22 is between 10% and 50%, it is considered as moderate lithium plating; and if the lithium plating area on the surface of the bent portion 230 of the negative electrode 22 is greater than 50%, it is considered as severe lithium plating. Products with severe lithium plating are unqualified products.

[0062] When the positive electrode active material of the battery is a nickel-cobalt-manganese ternary cathode, the upper limit voltage is 4.25V and the lower limit voltage is 2.5V. When the positive electrode active material of the battery is lithium iron phosphate, the upper limit voltage is 3.6V and the lower limit voltage is 2.5V.

[0063] In this test, the positive electrode active material of the battery was selected from a nickel-cobalt-manganese ternary LiNi0.6Co material. 0.2 Mn 0.2 Taking O2 as an example, the mass ratio of positive electrode active material: conductive agent: binder satisfies 96:2:2; the negative electrode active material is selected from artificial graphite, and the ratio of negative electrode active material: conductive agent: thickener: binder satisfies 95:2:1:2.

[0064] The test table is as follows: According to the table above, in Examples 1-16, the value of formula (F×A) / d is within the range of the restrictions of this application, and the product is a qualified product. In Comparative Examples 1-3, the value of formula ((F×A) / d) is not within the range of the restrictions of this application, and the product has at least one unqualified performance.

[0065] In the description of this specification, references to terms such as "some embodiments," "other embodiments," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions 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 one or more embodiments or examples.

[0066] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art will be able to make various obvious changes, readjustments, and substitutions without departing from the scope of protection of the present invention. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A battery cell, characterized in that, The battery cell is formed by winding an electrode and a separator along a first direction. The battery cell includes a stress concentration region and a flat region. The stress concentration region is formed by bending the electrode. Adhesive tape is adhered to the surface of the electrode, and at least a portion of the adhesive tape is disposed in the stress concentration region. Wherein: In a second direction, at least one end of the tape extends beyond the electrode. The tape includes a substrate layer and an adhesive layer. The substrate layer includes a non-adhesive region extending beyond the adhesive layer. The electrode includes a body layer and an active material layer coated on at least one surface of the body layer. The body layer also includes an inactive material region. The adhesive layer at least partially overlaps with the inactive material region. The peel force between the adhesive layer and the electrode is FN / cm. The area of ​​the non-adhesive region is A, representing a percentage of the area of ​​the substrate layer. In the second direction, the total height of the tape extending beyond the electrode is dmm. F, A, and d satisfy the relationship: 0.4 × 10⁻⁶. -2 ≤(F×A) / d≤241.7×10 -2 .

2. The battery cell according to claim 1, characterized in that, Along the second direction, the tape extends beyond one end of the electrode by a distance d1mm, where d1 satisfies the relationship: 0.1mm≤d1mm≤5mm.

3. The battery cell according to claim 1, characterized in that, Along the second direction, both ends of the tape extend beyond the end of the electrode sheet by d1mm and d2mm respectively, and d1 and d2 satisfy the relationship: 1mm≤d1mm+d2mm≤10mm.

4. The battery cell according to claim 1, characterized in that, In the second direction, at least one end of the tape extends beyond the diaphragm by a total distance of d3mm, where d3 satisfies the relationship: 0.5mm≤d3mm≤10mm.

5. The battery cell according to claim 1, characterized in that, The current collector of the electrode includes an aluminum layer. Along the first direction, the size of a single piece of the tape is L1mm, and L1 satisfies the relationship: 10mm≤L1mm≤30mm.

6. The battery cell according to claim 1, characterized in that, The ratio A of the area of ​​the non-adhesive region to the area of ​​the substrate layer ranges from 0.05 to 0.5; and / or: The peel force FN / cm between the adhesive layer and the electrode sheet ranges from 0.6 N / cm to 3.0 N / cm; and / or: In the second direction, the value of the total height dmm of the tape exceeding the electrode sheet ranges from 0.5mm to 10mm.

7. The battery cell according to any one of claims 1-6, characterized in that, Along the first direction, the non-adhesive area is disposed at at least one end of the tape.

8. The battery cell according to claim 7, characterized in that, Along the first direction, the size of the non-adhesive area is L2mm, where L2 satisfies the relationship: 1mm≤L2mm≤10mm.

9. The battery cell according to claim 7, characterized in that, Along the first direction, the non-adhesive area is disposed at both ends of the tape, and the peel force FN / cm between the adhesive layer and the electrode sheet ranges from 0.8N / cm to 3.0N / cm.

10. The battery cell according to any one of claims 1-6, characterized in that, Along the second direction, the non-adhesive area is spaced apart from the end of the electrode, and the spacing ranges from 0.1mm to 9mm.

11. The battery cell according to claim 10, characterized in that, Along the first direction, the non-adhesive area is spaced apart from the end of the tape, and the spacing ranges from 1mm to 14mm.

12. The battery cell according to any one of claims 1-6, characterized in that, Through holes are provided on the substrate layer, and at least some of the through holes are provided on the non-adhesive area.

13. The battery cell according to claim 12, characterized in that, The area of ​​a single through-hole ranges to 78.5 μm. 2 -196250μm 2 .

14. The battery cell according to any one of claims 1-6, characterized in that, The peel force F1 between the substrate layer and the adhesive layer is greater than the peel force F between the adhesive layer and the electrode.

15. The battery cell according to any one of claims 1-6, characterized in that, The thickness of the substrate layer is 10μm-70μm; and / or: The thickness of the adhesive layer is 10μm-50μm.

16. The battery cell according to any one of claims 1-6, characterized in that, Along the first direction, the adhesive tape is provided in the stress concentration areas on both sides of the battery cell.

17. The battery cell according to any one of claims 1-6, characterized in that, The tape is placed inside the first five turns during the winding process of the battery cell.

18. The battery cell according to any one of claims 1-6, characterized in that, The active material layer is provided on both the upper and lower surfaces of the electrode along its thickness direction, and the adhesive tape is provided on both the upper and lower surfaces of the electrode.

19. The battery cell according to claim 18, characterized in that, Along the second direction, the tape extends beyond the active material layer on the electrode, and the portions of the tape extending beyond the active material layer are bonded together on the upper and lower surfaces of the electrode.

20. A battery, characterized in that, It includes a housing and a battery cell as described in any one of claims 1-19, wherein the battery cell is disposed inside the housing.

21. The battery according to claim 20, characterized in that, The battery cell consists of at least two cells, F, A, and d, satisfying the relationship: 2.2 × 10⁻⁶. -2 ≤(F×A) / d≤191.7×10 -2 .

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