Wound cell, battery cell, and battery device

Abstract

The invention discloses a winding battery cell, a battery monomer and a battery device. The winding battery cell comprises a negative pole piece, a positive pole piece and a diaphragm, the negative pole piece comprises a negative pole piece body, a negative pole lug and a first protective layer, the negative pole lug is connected to at least one end of the negative pole piece body in the width direction, the first protective layer covers the joint of the negative pole lug and the negative pole piece body, and the first protective layer is an ion conducting layer. The positive pole piece comprises a positive pole piece body and a positive pole lug, and the positive pole lug is connected to at least one end of the positive pole piece body in the width direction. According to the winding battery cell disclosed by the embodiment of the invention, the migration resistance of lithium ions is reduced, precipitated lithium near the first protective layer is reduced, and a contact short circuit phenomenon caused by the fact that lithium dendrites pierce the diaphragm is avoided.

Description

Technical Field

[0001] This invention relates to the field of batteries, and in particular to a wound battery cell, a battery cell, and a battery device. Background Technology

[0002] In a wound battery cell formed by connecting electrodes and tabs, burrs and / or solder bumps on the tabs may puncture the separator between the positive and negative electrodes, causing a short circuit between them. In related technologies, protective tape is typically applied at the connection point between the electrodes and tabs; however, during charging, lithium ions can precipitate at the edges of the protective tape, forming lithium dendrites. These dendrites may puncture the separator, leading to a short circuit between the positive and negative electrodes. Therefore, improvements are needed. Summary of the Invention

[0003] The present invention aims to at least solve one of the technical problems existing in the prior art. To this end, one object of the present invention is to provide a wound battery cell in which the first protective layer is an ion-conducting layer. During charging, lithium ions migrating from the positive electrode to the negative electrode can penetrate the first protective layer and embed themselves in the negative electrode, thereby reducing the migration resistance of lithium ions, reducing lithium deposition near the first protective layer, and avoiding short circuits between the positive and negative electrodes caused by lithium dendrites piercing the separator.

[0004] The present invention also proposes a battery cell comprising the above-mentioned wound cell.

[0005] The present invention also proposes a battery device comprising the above-mentioned battery cells.

[0006] According to a first aspect of the present invention, a wound battery cell includes: a negative electrode sheet, comprising a negative electrode sheet body, a negative electrode tab, and a first protective layer, wherein the negative electrode tab is connected to at least one end of the negative electrode sheet body along the width direction, and the first protective layer covers the connection between the negative electrode tab and the negative electrode sheet body, wherein the first protective layer is an ion-conducting layer; a positive electrode sheet, comprising a positive electrode sheet body and a positive electrode tab, wherein the positive electrode tab is connected to at least one end of the positive electrode sheet body along the width direction; and a separator, sandwiched between the positive electrode sheet and the negative electrode sheet.

[0007] According to the embodiments of the present invention, the wound battery cell, by covering the connection between the negative electrode tab and the negative electrode body with a first protective layer, protects the burrs and / or solder protrusions on the negative electrode tab, preventing the burrs and / or solder protrusions from piercing the separator and causing a short circuit inside the battery; and by making the first protective layer an ion-conducting layer, during charging, lithium ions migrating from the positive electrode to the negative electrode can penetrate the first protective layer and embed into the negative electrode, reducing the migration resistance of lithium ions, reducing lithium plating near the first protective layer, and preventing short circuits between the positive and negative electrodes caused by lithium dendrites piercing the separator.

[0008] According to some embodiments of the present invention, the negative electrode tab is welded to the negative electrode body.

[0009] According to some embodiments of the present invention, the first protective layer is a porous ion-conducting adhesive paper; and / or, the first protective layer is formed with a plurality of ion-conducting pores for ion passage.

[0010] According to some embodiments of the present invention, the first protective layer includes a stacked substrate layer and an adhesive layer, the adhesive layer being used to bond and fix the first protective layer to the negative electrode body, and the ion-conducting pore penetrating the substrate layer and the adhesive layer along the thickness direction of the first protective layer.

[0011] According to some embodiments of the present invention, the substrate layer is made of polyethylene or polypropylene.

[0012] According to some embodiments of the present invention, the second protective layer is a non-ion-conducting layer; and / or, the second protective layer is adhesive paper.

[0013] According to some embodiments of the present invention, the positive electrode further includes a second protective layer, which covers the connection between the positive electrode tab and the positive electrode body.

[0014] According to some embodiments of the present invention, the negative electrode sheet is provided with the first protective layer on both sides along the thickness direction; and / or, the positive electrode sheet is provided with the second protective layer on both sides along the thickness direction.

[0015] According to some embodiments of the present invention, the length of the first protective layer along the length direction of the negative electrode body is W1, 2mm≤W1≤25mm, and the width of the first protective layer along the width direction of the electrode body is L1, 5mm≤L1≤45mm; and / or, the length of the second protective layer along the length direction of the positive electrode body is W2, 4mm≤W2≤35mm, and the width of the second protective layer along the width direction of the positive electrode body is L2, 7mm≤L2≤55mm.

[0016] According to some embodiments of the present invention, the length of the negative electrode tab along the length direction of the negative electrode body is A1, the length of the first protective layer along the length direction of the negative electrode body is W1, and the ratio of W1 to A1 is in the range of 1 to 2; the length of the positive electrode tab along the length direction of the positive electrode body is A2, the length of the second protective layer along the length direction of the positive electrode body is W2, and the ratio of W2 to A2 is in the range of 1 to 2.

[0017] According to some embodiments of the present invention, the position corresponding to the negative electrode body and the positive electrode tab is a positive electrode tab corresponding region, and the positive electrode tab corresponding region is provided with a third protective layer, which is an ion-conducting layer.

[0018] According to some embodiments of the present invention, the negative electrode sheet includes a negative electrode active material layer, the negative electrode active material layer covers both sides of the negative electrode sheet body along the thickness direction, the area where the negative electrode sheet body is connected to the negative electrode tab is a negative electrode empty foil area, the negative electrode active material layer covers the other areas of the negative electrode sheet body except for the negative electrode empty foil area, and the third protective layer covers the side of the negative electrode active material layer opposite to the negative electrode sheet body.

[0019] According to some embodiments of the present invention, the positive electrode sheet includes a positive electrode active material layer, which covers both sides of the positive electrode sheet body along the thickness direction. The area where the positive electrode sheet body is connected to the positive electrode tab is a positive electrode empty foil area. The positive electrode active material layer covers the other areas of the positive electrode sheet body excluding the positive electrode empty foil area. The position of the positive electrode sheet body corresponding to the negative electrode tab is a negative electrode tab corresponding area. A fourth protective layer is provided on the surface of the negative electrode tab corresponding area. The fourth protective layer covers the side of the positive electrode active material layer away from the positive electrode sheet body. The fourth protective layer is a non-ion-conducting layer.

[0020] A battery cell according to a second aspect of the present invention includes: a housing; and a wound cell according to a first aspect of the present invention, wherein the wound cell is disposed within the housing.

[0021] According to the embodiments of the present invention, the battery cell includes a wound cell according to the first aspect of the present invention, which avoids the weld seam from piercing the separator and causing a short circuit inside the battery; and reduces the migration resistance of lithium ions, reduces lithium plating near the first protective layer, and avoids the short circuit phenomenon between the positive electrode and the negative electrode caused by lithium dendrites piercing the separator.

[0022] A battery device according to a third aspect of the present invention includes: a housing; and a plurality of battery cells disposed within the housing, wherein the battery cells are battery cells according to a second aspect of the present invention.

[0023] The battery device according to an embodiment of the present invention, by including a battery cell according to a second aspect of the present invention, avoids the weld seam piercing the separator, thus preventing a short circuit inside the battery; and reduces the migration resistance of lithium ions, reduces lithium plating near the first protective layer, and avoids short circuits between the positive and negative electrode plates caused by lithium dendrites piercing the separator.

[0024] 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

[0025] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0026] Figure 1 This is a simplified schematic diagram of a wound battery cell according to some embodiments of the present invention; Figure 2 yes Figure 1 A simplified schematic diagram of the negative electrode plate in the process; Figure 3 yes Figure 2 A simplified schematic diagram of the other side of the negative electrode plate; Figure 4 yes Figure 1 A simplified schematic diagram of the positive electrode plate in the process; Figure 5 yes Figure 4 A simplified schematic diagram of the other side of the positive electrode plate.

[0027] Figure label: 100. Winded battery cells; 1. Negative electrode sheet; 11. Negative electrode sheet body; 12. Negative electrode tab; 13. First protective layer; 14. Third protective layer; 15. Negative electrode active material layer; 16. Negative electrode empty foil area; 17. Corresponding area of ​​positive electrode tab; 2. Positive electrode plate; 21. Positive electrode plate body; 22. Positive electrode tab; 23. Second protective layer; 24. Fourth protective layer; 25. Positive active material layer; 26. Positive electrode empty foil region; 27. Corresponding region of negative electrode tab; 3. Diaphragm. Detailed Implementation

[0028] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0029] The following is for reference. Figures 1-5 A wound battery cell 100 according to an embodiment of the present invention is described.

[0030] Reference Figures 1-5 According to a first aspect of the present invention, a wound battery cell 100 includes: a negative electrode 1, a positive electrode 2, and a separator 3.

[0031] The negative electrode 1 includes a negative electrode body 11, a negative electrode tab 12, and a first protective layer 13. The negative electrode tab 12 is connected to at least one end of the negative electrode body 11 along its width direction. The first protective layer 13 covers the connection between the negative electrode tab 12 and the negative electrode body 11, and the first protective layer 13 is an ion-conducting layer. The positive electrode 2 includes a positive electrode body 21 and a positive electrode tab 22. The positive electrode tab 22 is connected to at least one end of the positive electrode body 21 along its width direction. A separator 3 is sandwiched between the positive electrode 2 and the negative electrode 1.

[0032] The negative electrode tab 12 can be located on one side of the negative electrode body 11 along its length, or it can be located in the middle of the negative electrode body 11 along its length. The positive electrode tab 22 can be located on one side of the positive electrode body 21 along its length, or it can be located in the middle of the positive electrode body 21 along its length.

[0033] For example, the wound cell 100 can be an MIT structure, an IMT structure, or an MMT structure.

[0034] The first protective layer 13 protects the connection structure formed between the negative electrode body 11 and the negative electrode tab 12, such as the solder mark, preventing the solder mark protrusion from piercing the separator 3 and causing a short circuit inside the battery. It also prevents the burrs formed by cutting the negative electrode tab 12 from piercing the separator 3 and causing a short circuit inside the battery.

[0035] In related technologies, the protective layer between the negative electrode body 11 and the negative electrode tab 12 is typically impermeable to lithium ions. During charging, due to the higher lithium ion density at the corresponding positions on the positive electrode 2 and the negative electrode tab 12, a large number of lithium ions escape from the positive electrode but cannot quickly embed into the negative electrode 1 due to the greater resistance from the protective layer. Therefore, lithium dendrites form near the protective layer. By making the first protective layer 13 an ion-conducting layer, during charging, lithium ions migrating from the positive electrode 2 to the negative electrode 1 can penetrate the first protective layer 13 and embed into the negative electrode 1. This reduces the migration resistance of lithium ions, reduces lithium deposition near the first protective layer 13, and avoids short circuits between the positive electrode 2 and the negative electrode 1 caused by lithium dendrites piercing the separator 3.

[0036] By setting the first protective layer 13, and making the first protective layer 13 an ion-conducting layer, not only are the burrs on the negative electrode tab 12 adequately protected and isolated, but the resistance encountered during lithium ion migration can also be reduced, allowing lithium ions to be inserted into the negative electrode more quickly. This can reduce the occurrence of lithium plating and avoid internal short circuits caused by the connection structure piercing the separator 3 and lithium dendrite precipitation piercing the separator 3, thus improving the safety of the battery.

[0037] According to the embodiment of the present invention, the wound battery cell 100, by providing a first protective layer 13 and a second protective layer 23, covers the connection between the negative electrode tab 12 and the negative electrode body 11. The first protective layer 13 protects the burrs on the negative electrode tab 12 and prevents the burrs from piercing the separator 3 and causing a short circuit inside the battery. Furthermore, by making the first protective layer 13 an ion-conducting layer, during the charging process, lithium ions migrating from the positive electrode 2 to the negative electrode 1 can penetrate the first protective layer 13 and embed into the negative electrode 1, reducing the migration resistance of lithium ions, reducing the lithium plating phenomenon near the first protective layer 13, and preventing the short circuit phenomenon between the positive electrode 2 and the negative electrode 1 caused by lithium dendrites piercing the separator 3.

[0038] According to some embodiments of the present invention, the negative electrode tab 12 is welded to the negative electrode body 11. By welding the negative electrode tab 12 to the negative electrode body 11, the connection process between the negative electrode tab 12 and the negative electrode body 11 can be simplified.

[0039] According to some embodiments of the present invention, the first protective layer 13 is a porous ion-conducting adhesive paper. By making the first protective layer 13 a porous ion-conducting adhesive paper, the porous ion-conducting adhesive paper can provide more channels for the migration of lithium ions. During battery charging, lithium ions extracted from the positive electrode can penetrate the first protective layer 13 more quickly to reach the negative electrode, which more effectively reduces the migration resistance of lithium ions and the lithium plating phenomenon near the first protective layer 13, avoiding short circuits between the positive electrode 2 and the negative electrode 1 caused by lithium dendrites piercing the separator 3. Furthermore, by making the first protective layer 13 an adhesive paper, the first protective layer 13 can be directly attached to the negative electrode body 11, making the manufacturing of the wound cell 100 simpler.

[0040] According to some embodiments of the present invention, the first protective layer 13 is formed with a plurality of ion-conducting holes for ion passage. By forming a plurality of ion-conducting holes in the first protective layer 13 for ion passage, more channels can be provided for the migration of lithium ions. During battery charging, lithium ions extracted from the positive electrode can pass through the first protective layer 13 more quickly through the plurality of ion-conducting holes to reach the negative electrode, thus more significantly reducing the migration resistance of lithium ions and more significantly reducing lithium plating near the first protective layer 13, and avoiding short circuits between the positive electrode 2 and the negative electrode 1 caused by lithium dendrites piercing the separator 3.

[0041] According to some embodiments of the present invention, the first protective layer 13 includes a stacked substrate layer and an adhesive layer. The adhesive layer is used to bond and fix the first protective layer 13 to the negative electrode body 11. The ion-conducting aperture penetrates the substrate layer and the adhesive layer along the thickness direction of the first protective layer 13. By including the stacked substrate layer and adhesive layer in the first protective layer 13, the adhesive layer can adhere the substrate layer to the negative electrode body 11, making the fabrication of the wound cell 100 simpler. By making the ion-conducting aperture penetrate the substrate layer and the adhesive layer along the thickness direction of the first protective layer 13, the migration resistance of lithium ions can be reduced more effectively, allowing lithium ions to migrate faster and with stronger migration ability in the substrate layer and adhesive layer along the thickness direction of the first protective layer 13, enabling lithium ions to reach and embed into the negative electrode more quickly, and further reducing lithium plating near the first protective layer 13.

[0042] According to some embodiments of the present invention, the substrate layer is made of polyethylene or polypropylene. Using polyethylene or polypropylene as the substrate layer reduces costs and simplifies the manufacturing process.

[0043] According to some embodiments of the present invention, the second protective layer 23 is a non-ion-conducting layer. That is, lithium ions have difficulty penetrating the second protective layer 23 or migrating within the second protective layer 23. Since the lithium ion density is higher near the positive electrode tab 22, by making the second protective layer 23 a non-ion-conducting layer, the deintercalation and intercalation of lithium ions near the positive electrode tab 22 can be appropriately reduced, avoiding excessive lithium ions deintercalating from the vicinity of the positive electrode tab 22 and failing to quickly intercalate into the negative electrode plate 1, thus reducing lithium deposition and the lithium deposition phenomenon on the negative electrode plate 1 near the position corresponding to the positive electrode tab 22.

[0044] According to some embodiments of the present invention, the positive electrode 2 further includes a second protective layer 23, which covers the positive electrode tab 22 and the positive electrode body 21. The second protective layer 23 protects the connection between the positive electrode tab 22 and the positive electrode body 21, preventing the connection structure from piercing the separator 3 and causing an internal short circuit in the battery, and also preventing burrs formed by cutting the positive electrode tab 22 from piercing the separator and causing an internal short circuit in the battery.

[0045] Furthermore, since the lithium plating phenomenon near the first protective layer 13 is reduced, the length of the second protective layer 23 along the extension direction of the positive electrode 2 can be appropriately reduced, and the coverage area of ​​the second protective layer 23 on the positive electrode body 21 can be appropriately reduced, thereby appropriately increasing the energy density of the battery while avoiding lithium plating.

[0046] According to some embodiments of the present invention, the second protective layer 23 is adhesive tape. By making the second protective layer 23 adhesive tape, the second protective layer 23 can be directly attached to the positive electrode body 21, making the fabrication of the wound cell 100 simpler. For example, the second protective layer 23 is green adhesive.

[0047] Reference Figure 2 and Figure 3 According to some embodiments of the present invention, a first protective layer 13 is provided on both sides of the negative electrode sheet 1 along the thickness direction. By providing a first protective layer 13 on both sides of the negative electrode sheet 1 along the thickness direction, the burrs on the edge of the negative electrode tab 12 can be protected from piercing the separator 3 and causing an internal short circuit in the battery.

[0048] Reference Figure 4 and Figure 5 According to some embodiments of the present invention, a second protective layer 23 is provided on both sides of the positive electrode 2 along the thickness direction. By providing a second protective layer 23 on both sides of the positive electrode 2 along the thickness direction, the burrs on the edge of the positive electrode tab 22 can be protected from piercing the separator 3 and causing an internal short circuit in the battery.

[0049] Reference Figure 2 According to some embodiments of the present invention, the length of the first protective layer 13 along the length direction of the negative electrode body 11 is W1, where 2mm ≤ W1 ≤ 25mm, and the width of the first protective layer 13 along the width direction of the electrode body is L1, where 5mm ≤ L1 ≤ 45mm. For example, the value of W1 can be 2mm, 5mm, 10mm, 15mm, 20mm, 25mm, etc., and the value of L1 can be 5mm, 10mm, 15mm, 20mm, 25mm, 30mm, 35mm, 40mm, 45mm, etc.

[0050] By ensuring that the length W1 of the first protective layer 13 along the length direction of the negative electrode body 11 is not less than 2 mm, the first protective layer 13 can fully protect the weld between the negative electrode tab 12 and the negative electrode body 11, thus effectively preventing the weld from piercing the separator 3 and causing a short circuit inside the battery. By ensuring that the length W1 of the first protective layer 13 along the length direction of the negative electrode body 11 is not greater than 25 mm, it is possible to avoid the first protective layer 13 being too large, which would result in too much area of ​​the negative electrode body 11 being covered by the first protective layer 13, thereby reducing the impact of the first protective layer 13 on the lithium-ion migration capability, saving materials, and reducing costs. By ensuring that the width L1 of the first protective layer 13 along the width direction of the electrode body is not less than 5mm, the first protective layer 13 can fully protect the weld between the negative electrode tab 12 and the negative electrode body 11, thus effectively preventing the weld from piercing the separator 3 and causing a short circuit inside the battery. By ensuring that the width L1 of the first protective layer 13 along the width direction of the electrode body is not greater than 45mm, the first protective layer 13 can be prevented from being too large, thus avoiding excessive coverage of the negative electrode body 11 area by the first protective layer 13, reducing the impact of the first protective layer 13 on the lithium-ion migration capability, and saving materials and reducing costs.

[0051] Reference Figure 4According to some embodiments of the present invention, the length of the second protective layer 23 along the length direction of the positive electrode body 21 is W2, 4mm≤W2≤35mm, and the width of the second protective layer 23 along the width direction of the positive electrode body 21 is L2, 7mm≤L2≤55mm.

[0052] For example, the value of W2 can be 4mm, 5mm, 10mm, 15mm, 20mm, 25mm, 30mm, 35mm, etc., and the value of L2 can be 7mm, 10mm, 15mm, 20mm, 30mm, 40mm, 50mm, 55mm, etc.

[0053] By ensuring that the length W2 of the second protective layer 23 along the length direction of the positive electrode body 21 is not less than 4 mm, the second protective layer 23 can fully protect the weld between the positive electrode tab 22 and the positive electrode body 21, thus effectively preventing the weld from piercing the separator 3 and causing a short circuit inside the battery. By ensuring that the length W2 of the second protective layer 23 along the length direction of the positive electrode body 21 is not greater than 35 mm, it is possible to avoid the second protective layer 23 being too large, which would result in too much area of ​​the positive electrode body 21 being covered by the second protective layer 23, thereby reducing the impact of the second protective layer 23 on the lithium-ion migration capability, saving materials, and reducing costs. By ensuring that the width L2 of the second protective layer 23 along the width direction of the positive electrode body 21 is not less than 7mm, the second protective layer 23 can fully protect the weld between the positive electrode tab 22 and the positive electrode body 21, thus preventing the weld from piercing the separator 3 and causing a short circuit inside the battery. By ensuring that the width L2 of the second protective layer 23 along the width direction of the positive electrode body 21 is not greater than 55mm, the second protective layer 23 can be prevented from being too large, thus avoiding excessive coverage of the positive electrode body 21 area by the second protective layer 23, reducing the impact of the second protective layer 23 on the lithium-ion migration capability, saving materials, and reducing costs.

[0054] Reference Figure 2 According to some embodiments of the present invention, the length of the negative electrode tab 12 along the length direction of the negative electrode body 11 is A1, and the length of the first protective layer 13 along the length direction of the negative electrode body 11 is W1, with the ratio of W1 to A1 ranging from 1 to 2. For example, the ratio of W1 to A1 can be 1, 1.2, 1.4, 1.6, 1.8, 2, etc. By making the ratio of W1 to A1 not less than 1, the length of the first protective layer 13 along the length direction of the negative electrode body 11 can be greater than the length of the negative electrode tab 12, so that the first protective layer 13 can fully protect the weld between the negative electrode tab 12 and the negative electrode body 11, and fully avoid the weld from piercing the separator 3 and causing a short circuit inside the battery; by making the ratio of W1 to A1 not greater than 2, it can be avoided that the first protective layer 13 is too large, resulting in too much area of ​​the negative electrode body 11 covered by the first protective layer 13, reducing the impact of the first protective layer 13 on the lithium-ion migration ability, and saving materials and reducing costs.

[0055] Reference Figure 4 The length of the positive electrode tab 22 along the length of the positive electrode body 21 is A2, and the length of the second protective layer 23 along the length of the positive electrode body 21 is W2. The ratio of W2 to A2 is in the range of 1 to 2. For example, the ratio between W2 and A2 can be 1, 1.2, 1.4, 1.6, 1.8, 2, etc.

[0056] By ensuring that the ratio of W2 to A2 is not less than 1, the length of the second protective layer 23 along the length direction of the positive electrode body 21 can be greater than the length of the positive electrode tab 22. This allows the second protective layer 23 to fully protect the weld between the positive electrode tab 22 and the positive electrode body 21, effectively preventing the weld from piercing the separator 3 and causing a short circuit inside the battery. By ensuring that the ratio of W2 to A2 is not greater than 2, the second protective layer 23 can be prevented from being too large, thus avoiding excessive coverage of the positive electrode body 21 area by the second protective layer 23. This reduces the impact of the second protective layer 23 on the lithium-ion migration capability, saves materials, and lowers costs.

[0057] Reference Figure 2 and Figure 3 According to some embodiments of the present invention, the position corresponding to the negative electrode body 11 and the positive electrode tab 22 is a positive electrode tab corresponding region 17. The positive electrode tab corresponding region 17 is provided with a third protective layer 14, which is an ion-conducting layer. The energy density is relatively high near the positive electrode tab 22. During battery charging, a large number of lithium ions escape from the position near the positive electrode tab 22 and migrate to the positive electrode tab corresponding region 17, where they are embedded. By making the third protective layer 14 an ion-conducting layer, during charging, lithium ions that migrate from the vicinity of the positive electrode tab 22 to the positive electrode tab corresponding region 17 can penetrate the third protective layer 14 and embed into the negative electrode 1, reducing the migration resistance of lithium ions, reducing lithium plating near the third protective layer 14, and avoiding short circuits between the positive electrode 2 and the negative electrode 1 caused by lithium dendrites piercing the separator 3.

[0058] Reference Figure 2 and Figure 3 According to some embodiments of the present invention, the negative electrode 1 includes a negative electrode active material layer 15, which covers both sides of the negative electrode body 11 along the thickness direction. The connection area between the negative electrode body 11 and the negative electrode tab 12 is the negative electrode empty foil area 16. The negative electrode active material layer 15 covers the other areas of the negative electrode body 11 except for the negative electrode empty foil area 16. A third protective layer 14 covers the side of the negative electrode active material layer 15 opposite to the negative electrode body 11. By having the third protective layer 14 cover the side of the negative electrode active material layer 15 opposite to the negative electrode body 11, compared to directly attaching the third protective layer 14 to the surface of the negative electrode body 11, the coverage area of ​​the negative electrode active material layer 15 can be increased, thereby increasing the battery capacity.

[0059] Reference Figure 4 and Figure 5 According to some embodiments of the present invention, the positive electrode 2 includes a positive active material layer 25, which covers both sides of the positive electrode body 21 along the thickness direction. The connection area between the positive electrode body 21 and the positive electrode tab 22 is the positive empty foil area 26. The positive active material layer 25 covers the other areas of the positive electrode body 21 except for the positive empty foil area 26. The position corresponding to the negative electrode tab 12 of the positive electrode body 21 is the negative electrode tab corresponding area 27. A fourth protective layer 24 is provided on the surface of the negative electrode tab corresponding area 27. The fourth protective layer 24 covers the side of the positive active material layer 25 away from the positive electrode body 21. The fourth protective layer 24 is a non-ion-conducting layer.

[0060] For example, the fourth protective layer 24 covers the side of the positive electrode active material layer 25 that is away from the positive electrode body 21.

[0061] Since the lithium ion density in the region 27 corresponding to the negative electrode tab is greater, by setting a fourth protective layer 24 on the surface of the region 27 corresponding to the negative electrode tab, and the fourth protective layer 24 is a non-ion-conducting layer, the fourth protective layer 24 can appropriately reduce the lithium ion deintercalation in the region 27 corresponding to the negative electrode tab, avoid excessive lithium ions deintercalating from the vicinity of the region 27 corresponding to the negative electrode tab and making it difficult to quickly intercalate into the negative electrode sheet 1, thus reducing lithium deposition and reducing the lithium deposition phenomenon near the first protective layer 13.

[0062] According to a second aspect of the present invention, a battery cell includes: a housing and a wound cell 100 according to a first aspect of the present invention, wherein the wound cell 100 is disposed within the housing.

[0063] According to the embodiments of the present invention, the battery cell includes the wound cell 100 according to the first aspect of the present invention, which avoids the weld seam from piercing the separator 3 and causing a short circuit inside the battery; and reduces the migration resistance of lithium ions, reduces the lithium plating phenomenon near the first protective layer 13, and avoids the short circuit phenomenon between the positive electrode 2 and the negative electrode 1 caused by lithium dendrites piercing the separator 3.

[0064] A battery device according to a third aspect of the present invention includes: a housing and a plurality of battery cells, wherein the plurality of battery cells are disposed in the housing, and the battery cells are battery cells according to a second aspect of the present invention.

[0065] According to the battery device of the present invention, by including the battery cell according to the second aspect of the present invention, the internal short circuit of the battery is avoided due to the weld seam piercing the separator 3; and the migration resistance of lithium ions is reduced, the lithium deposition phenomenon near the first protective layer 13 is reduced, and the short circuit phenomenon between the positive electrode 2 and the negative electrode 1 caused by lithium dendrites piercing the separator 3 is avoided.

[0066] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0067] In the description of this invention, "first feature" and "second feature" may include one or more of the features.

[0068] In the description of this invention, "a plurality of" means two or more.

[0069] In the description of this invention, the first feature being "above" or "below" the second feature may include the first and second features being in direct contact, or it may include the first and second features not being in direct contact but being in contact through another feature between them.

[0070] In the description of this invention, the terms "above," "over," and "on top" for the first feature and the second feature include the first feature being directly above or diagonally above the second feature, or simply indicating that the first feature is at a higher horizontal level than the second feature.

[0071] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," 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.

[0072] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A wound battery cell, characterized in that, include: A negative electrode sheet includes a negative electrode sheet body, a negative electrode tab, and a first protective layer. The negative electrode tab is connected to at least one end of the negative electrode sheet body along the width direction. The first protective layer covers the connection between the negative electrode tab and the negative electrode sheet body. The first protective layer is an ion-conducting layer. A positive electrode plate includes a positive electrode plate body and a positive electrode tab, wherein the positive electrode tab is connected to at least one end of the positive electrode plate body along the width direction; A diaphragm is sandwiched between the positive electrode and the negative electrode.

2. The wound battery cell according to claim 1, characterized in that, The negative electrode tab is welded to the negative electrode body.

3. The wound battery cell according to claim 1, characterized in that, The first protective layer is a porous ion-conducting adhesive paper; and / or, the first protective layer is formed with a plurality of ion-conducting pores for ion passage.

4. The wound battery cell according to claim 3, characterized in that, The first protective layer includes a stacked substrate layer and an adhesive layer. The adhesive layer is used to bond and fix the first protective layer to the negative electrode body. The ion-conducting pores penetrate the substrate layer and the adhesive layer along the thickness direction of the first protective layer.

5. The wound battery cell according to claim 4, characterized in that, The substrate layer is made of polyethylene or polypropylene.

6. The wound battery cell according to claim 1, characterized in that, The positive electrode also includes a second protective layer, which covers the connection between the positive electrode tab and the positive electrode body.

7. The wound battery cell according to claim 6, characterized in that, The second protective layer is a non-ion-conducting layer; and / or, the second protective layer is adhesive paper.

8. The wound battery cell according to claim 7, characterized in that, The negative electrode sheet is provided with the first protective layer on both sides along the thickness direction; and / or, the positive electrode sheet is provided with the second protective layer on both sides along the thickness direction.

9. The wound battery cell according to claim 7, characterized in that, The length of the first protective layer along the length direction of the negative electrode body is W1, 2mm≤W1≤25mm, and the width of the first protective layer along the width direction of the electrode body is L1, 5mm≤L1≤45mm; and / or, the length of the second protective layer along the length direction of the positive electrode body is W2, 4mm≤W2≤35mm, and the width of the second protective layer along the width direction of the positive electrode body is L2, 7mm≤L2≤55mm.

10. The wound battery cell according to claim 7, characterized in that, The length of the negative electrode tab along the length of the negative electrode body is A1, and the length of the first protective layer along the length of the negative electrode body is W1, with the ratio of W1 to A1 ranging from 1 to 2; the length of the positive electrode tab along the length of the positive electrode body is A2, and the length of the second protective layer along the length of the positive electrode body is W2, with the ratio of W2 to A2 ranging from 1 to 2.

11. The wound battery cell according to any one of claims 7-10, characterized in that, The position corresponding to the negative electrode body and the positive electrode tab is the positive electrode tab corresponding region. The positive electrode tab corresponding region is provided with a third protective layer, which is an ion-conducting layer.

12. The wound battery cell according to claim 11, characterized in that, The negative electrode sheet includes a negative electrode active material layer, which covers both sides of the negative electrode sheet body along the thickness direction. The area where the negative electrode sheet body is connected to the negative electrode tab is a negative electrode empty foil area. The negative electrode active material layer covers the other areas of the negative electrode sheet body except for the negative electrode empty foil area. The third protective layer covers the side of the negative electrode active material layer opposite to the negative electrode sheet body.

13. The wound battery cell according to any one of claims 1-10, characterized in that, The positive electrode includes a positive active material layer, which covers both sides of the positive electrode body along the thickness direction. The area where the positive electrode body is connected to the positive electrode tab is the positive empty foil area. The positive active material layer covers the other areas of the positive electrode body except for the positive empty foil area. The position of the positive electrode body corresponding to the negative electrode tab is the negative electrode tab corresponding area. A fourth protective layer is provided on the surface of the negative electrode tab corresponding area. The fourth protective layer covers the side of the positive active material layer away from the positive electrode body. The fourth protective layer is a non-ion-conducting layer.

14. A single battery cell, characterized in that, include: case; The wound cell according to any one of claims 1-13 is disposed within the housing.

15. A battery device, characterized in that, include: Box; Multiple battery cells are disposed within the housing, wherein the battery cells are as described in claim 14.

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