Battery and electric equipment

Abstract

The invention relates to the technical field of batteries, discloses a battery and electric equipment, and aims to solve the problem that tabs are easy to tear when the battery falls off and improve the safety of the battery. The battery comprises an electrode assembly, the electrode assembly comprises a body, and the body comprises a plurality of first pole pieces, a plurality of second pole pieces and a plurality of diaphragms which are stacked in a first direction; the tab comprises a second tab; the second tab is connected to one side of the second pole piece along the second direction; the tab comprises a bent part, and the bent part is bent towards the body and extends in the first direction; the adapter piece comprises a second adapter piece; one end of the second adapter is connected with the bending part of the second tab, and the part, connected with the bending part of the second tab, of the second adapter jointly forms a second connecting section; in the second direction, the distance between the second connecting section and the second pole piece is L1 mm, the tensile strength of the second tab is x MPa, and L1 meets the formula: (x * 0.001) 0.5 + 0.4 lt; l1lt; x is greater than 0.001 and smaller than 1.4; the first direction is perpendicular to the second direction.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and particularly to a battery and an electrical device using the same. Background Art

[0002] With the continuous progress of technology development, the demand for fast charging of batteries is becoming increasingly strong. Stacked batteries usually set multiple tabs to shorten the electron transmission path, reduce the impedance of the battery, and thus reduce the temperature rise during the fast charging of the battery.

[0003] Among them, the tabs are usually integrally formed from the foil of the electrode sheet. The tabs are connected to the adapter, and the electrical connection between the battery and external components is achieved through the adapter. However, during the falling process, the tabs are prone to tearing under the stress of the pulling between the electrode sheet and the adapter and external impacts, reducing the safety of the battery. Summary of the Invention

[0004] In view of this, the present invention provides a battery and an electrical device using the same to solve the problem that the tabs of the existing stacked battery are prone to tearing during falling, reducing the safety of the battery.

[0005] In a first aspect, the present invention provides a battery, including an electrode assembly. The electrode assembly includes: a body, the body includes a plurality of first electrode sheets, a plurality of second electrode sheets, and a plurality of separators stacked along a first direction; the polarities of the first electrode sheets and the second electrode sheets are opposite, and along the first direction, the first electrode sheets and the second electrode sheets are alternately arranged, and the separators are arranged between adjacent first electrode sheets and second electrode sheets; tabs, including second tabs; the second tabs are connected to one side of the second electrode sheets along a second direction; the tabs include a bent portion, the bent portion is bent towards the body and extends along the first direction; an adapter, including a second adapter; one end of the second adapter is connected to the bent portion of the second tabs, and the part of the second adapter connected to the bent portion of the second tabs together forms a second connection segment; along the second direction, the distance between the second connection segment and the second electrode sheet is L1 mm, the tensile strength of the second tabs is x MPa, and L1 satisfies: (x * 0.001)^0.5 + 0.4 < L1 < x * 0.001 + 1.4; the first direction is perpendicular to the second direction.

[0006] In an optional embodiment, the first electrode sheets are positive electrode sheets, and the second electrode sheets are negative electrode sheets; and / or, along the first direction, the projected area of the second electrode sheets is larger than the projected area of the first electrode sheets.

[0007] In an optional embodiment, the battery includes a shell, and the body and the tab are all located inside the shell; the adapter includes a first connecting portion and a second connecting portion that are connected and at an angle; the first connecting portion of the second adapter is connected to the bent portion of the second tab, and the portion where the first connecting portion of the second adapter is connected to the bent portion of the second tab together forms a second connecting section; the second connecting portion extends along the second direction, and at least part of the structure is located outside the shell; the shell has a first edge seal; along the first direction, the first edge seal is located on the side of the second connecting portion away from the first connecting portion; along the first direction, the spacing between the bent portion of the second tab and the first edge seal is L2, and L2 satisfies: 0.15mm≤L2≤2mm.

[0008] In an optional embodiment, the electrode tab includes a first electrode tab, which is connected to one side of the first electrode sheet along the second direction; the adapter includes a first adapter; the first connecting portion of the first adapter is connected to the bent portion of the first electrode tab, and the portion where the first connecting portion of the first adapter is connected to the bent portion of the first electrode tab together forms a first connecting segment; the first connecting portion of the first adapter is welded to the bent portion of the first electrode tab, and a welding area is formed on the first connecting segment; along the third direction, the size of the welding area of ​​the first connecting segment is W1 mm, the size of the first connecting portion of the first adapter is W2 mm, and W1 / W2 satisfies: 40%≤W1 / W2≤90%; and / or, the first connecting portion of the second adapter is welded to the bent portion of the second electrode tab, and a welding area is formed on the second connecting segment; along the third direction, the size of the welding area of ​​the second connecting segment is W3 mm, the size of the first connecting portion of the second adapter is W4 mm, and W3 / W4 satisfies: 40%≤W3 / W4≤90%; the third direction is perpendicular to both the first direction and the second direction.

[0009] In an optional embodiment, the first electrode tab is a positive electrode tab, and the second electrode tab is a negative electrode tab; the ratio of W1 / W2 in the first connecting segment is less than or equal to the ratio of W3 / W4 in the second connecting segment; preferably, in the first connecting segment, W1 / W2 satisfies: 40%≤W1 / W2≤80%; preferably, in the second connecting segment, W3 / W4 satisfies: 50%≤W3 / W4≤90%.

[0010] In an optional embodiment, the welding area is provided with a plurality of welding points, and each welding point is arranged at intervals; preferably, the number of welding points of the first connecting section is less than or equal to the number of welding points of the second connecting section; preferably, along the third direction, the spacing between two adjacent welding points is L3, and L3 satisfies: 0.1mm≤L3≤0.5mm; preferably, along the second direction, the spacing between two adjacent welding points is L4, and L4 satisfies: 0.1mm≤L4≤0.5mm.

[0011] In an optional embodiment, the battery includes an electrolyte, the electrolyte includes fluoroethylene carbonate, and the content of fluoroethylene carbonate in the electrolyte is f%; the area of ​​the weld in the welding region of the second connecting section is S mm2, and S satisfies: 0.5*f+4≤S≤3*f+4.

[0012] In an optional embodiment, the body has a first edge and two second edges; along the second direction, the end of the body away from the tab forms the first edge; along the third direction, two second edges are formed on both sides of the body; along the second direction, the spacing between the first edge and the shell is L5, and L5 satisfies: 0.2mm≤L5≤1.2mm; and / or, along the third direction, the spacing between the second edge and the shell is L6, and L6 satisfies: 0≤L6≤1mm; the third direction is perpendicular to both the first direction and the second direction.

[0013] In an optional embodiment, the main body has a first surface and a second surface arranged opposite to each other along a first direction, and a side surface connected between the first surface and the second surface; adhesive tape is provided on the edge of the main body, and along the width direction of the adhesive tape, the adhesive tape covers at least part of the structure of the first surface, the side surface and the second surface in sequence; along the width direction of the adhesive tape, the size of the adhesive tape is a mm, the size of the portion of the adhesive tape covering the first surface is b mm, and the size of the portion of the adhesive tape covering the second surface is c mm; when the battery is in a 100% SOC state, along the first direction, the vertical distance between the first surface and the second surface is d mm; wherein, ΔL=abcd, ΔL satisfies: 0.3mm≤ΔL≤2mm.

[0014] In a second aspect, the present invention further provides an electrical device, comprising: the battery as described above.

[0015] After a large number of experimental verifications, when the distance L1 between the bent part of the second tab and the second electrode plate satisfies the relationship of (x * 0.001)^0.5 + 0.4 < L1 < x * 0.001 + 1.4 with the tensile strength of the second tab, the problem that the second tab is easily torn when falling can be effectively alleviated, thereby improving the fracture failure problem of the second tab and greatly enhancing the safety of the battery. Through experimental verification, when L1 ≥ x * 0.001 + 1.4, that is, in this formula, when L1 is too large compared to x, the tab will shake or move during falling; at this time, the second tab is subjected to the pulling force of the second electrode plate and the first adapter and the stress of external impact, but the strength of the second tab is insufficient to cope with the stress received, resulting in the problem of tab tearing and reducing the battery safety. When L1 ≤ (x * 0.001)^0.5 + 0.4, that is, in this formula, when L1 is too small compared to x, during the falling process, the battery will be extruded by external force, causing the distance between the bent part and the second electrode plate to further decrease; at this time, although the strength of the second tab is sufficient to cope with the stress received during falling, the bent part or even the entire second tab is prone to interfere with the electrode plate, resulting in the problem of the tab being inserted backwards into the electrode plate and reducing the battery safety. Therefore, by using the technical solution of the present invention, the distance range between the bent part of the second tab and the second electrode plate is reasonably limited according to the tensile strength of the second tab, which can not only alleviate the problem of tab tearing but also avoid the interference between the tab and the electrode plate, greatly improving the safety performance of the battery cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0017] Figure 1 A cross-section of a battery according to an embodiment of the present invention Figure 1 ;

[0018] Figure 2 A schematic structural diagram of an electrode assembly of a battery according to an embodiment of the present invention Figure 1 ;

[0019] Figure 3 A schematic structural diagram of an electrode assembly of a battery according to an embodiment of the present invention Figure 2 ;

[0020] Figure 4 is Figure 3 a partial enlarged view of I in

[0021] Figure 5This is a schematic structural diagram of a battery adhesive tape according to an embodiment of the present invention;

[0022] Figure 6 This is a schematic structural diagram of a battery according to an embodiment of the present invention;

[0023] Figure 7 A cross-sectional view of a battery according to an embodiment of the present invention Figure 2 .

[0024] Description of reference numerals:

[0025] 1. Body; 11. Pole piece; 11a. First pole piece; 11b. Second pole piece; 12. Diaphragm; 13. First edge; 14. Second edge; 15. First surface; 16. Second surface; 17. Side surface; 18. Adhesive tape;

[0026] 2. Tab; 2a. First tab; 2b. Second tab; 21. Bend;

[0027] 3. Adapter; 3a. First adapter; 3b. Second adapter; 31. First connecting portion; 32. Second connecting portion;

[0028] 4. Shell; 41. First edge sealing;

[0029] 5. Connecting section; 50. Welding area; 501. Welding point; 51. First connecting section; 52. Second connecting section;

[0030] T, first direction; L, second direction; W, third direction; R - width direction of the adhesive tape. DETAILED DESCRIPTION

[0031] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative efforts shall fall within the scope of protection of the present invention.

[0032] With the continuous advancement of science and technology, the demand for fast charging of batteries is becoming increasingly strong. Laminated batteries usually have multiple tabs to shorten the transmission path of electrons, reduce the impedance of the battery, and thus reduce the temperature rise during the fast charging process of the battery. Among them, the tabs are usually formed into one piece from the foil of the pole piece, and the tabs are connected to the adapter, which realizes the electrical connection between the battery and external components. However, during the falling process, the tabs are easily torn due to the pulling between the pole piece and the adapter and the stress of external impact, which reduces the safety of the battery.

[0033] Therefore, the embodiments of the present application provide a battery and an electrical device that can solve the above problems.

[0034] The following combination Figures 1 to 7 , describing embodiments of the present invention.

[0035] According to an embodiment of the present invention, in one aspect, a battery is provided. In the embodiments of the present application, the battery may be a secondary battery, which refers to a battery whose active materials can be activated by recharging after the battery cells are discharged and can continue to be used. The battery may be a lithium-ion battery, a sodium-ion battery, a sodium-lithium-ion battery, a lithium metal battery, a sodium metal battery, a lithium-sulfur battery, a magnesium-ion battery, a nickel-metal hydride battery, a nickel-cadmium battery, a lead-acid battery, or the like, although the embodiments of the present application are not limited thereto.

[0036] like Figure 1 and Figure 6 As shown, the battery includes an electrode assembly, a shell 4 and an electrolyte (not shown in the figure).

[0037] Among them, the electrode assembly includes a body 1, a tab 2 and an adapter 3. Specifically, the body 1 includes a plurality of pole pieces 11 and a plurality of diaphragms 12 stacked along a first direction T. The pole piece 11 includes a first pole piece 11a and a second pole piece 11b with opposite polarities. It can be understood that there are multiple first pole pieces 11a and second pole pieces 11b. Along the first direction T, the first pole piece 11a and the second pole piece 11b are alternately arranged, and the diaphragm 12 is arranged between adjacent first pole pieces 11a and second pole pieces 11b. It can be understood that the first direction T is also the thickness direction of the battery, that is, the thickness direction of the pole piece 11 itself, that is, the thickness direction of the diaphragm 12 itself.

[0038] It is understood that one of the first electrode sheet 11a and the second electrode sheet 11b is the positive electrode sheet, and the other is the negative electrode sheet. During the charge and discharge process of the battery cell, active ions (such as lithium ions) are inserted and removed back and forth between the positive and negative electrode sheets. The separator 12 is provided between the positive and negative electrode sheets to prevent short circuits between the positive and negative electrodes while allowing the active ions to pass through.

[0039] Among them, the positive electrode sheet may include a positive electrode foil layer and a positive electrode active material layer provided on at least one surface of the positive electrode foil layer. The negative electrode sheet may include a negative electrode foil layer and a negative electrode active material layer provided on at least one surface of the negative foil layer. The positive electrode foil layer may be an aluminum foil or an aluminum foil with a coating treatment on the surface, and the negative electrode foil layer may be a copper foil or a copper foil with a coating treatment on the surface. The positive electrode active material layer and the negative electrode active material layer may adopt active materials for batteries that are well known in the art. The present application has no particular restrictions on the type of the diaphragm 12, and any well-known porous structure diaphragm with good chemical stability and mechanical stability may be selected.

[0040] Furthermore, the tab 2 can conduct current from the electrode assembly. The tab 2 includes a first tab 2a and a second tab 2b. The first tab 2a is connected to one side of the first pole piece 11a along the second direction L, and the second tab 2b is connected to one side of the second pole piece 11b along the second direction L. The second direction L is perpendicular to the first direction T, and the second direction L can be understood as the length direction of the battery. The first tab 2a and the second tab 2b can be located on the same side of the second direction L of the body 1, or can be located on both sides of the second direction L of the body 1. Preferably, the first tab 2a and the second tab 2b can be located on the same side of the second direction L of the body 1 to save space and improve the energy density of the battery.

[0041] It can be understood that one of the first electrode tab 2a and the second electrode tab 2b is a positive electrode tab, and the other is a negative electrode tab.

[0042] The tab 2 is typically formed integrally with the foil layer of the electrode 11. During actual production, the tab 2 is typically formed by cutting a hollow portion of the foil layer of the electrode 11. This means the tab 2 is typically made of the same material as the foil layer of the electrode 11 to which it is connected. Specifically, the first tab 2a is made of the same material as the foil layer of the first electrode 11a, and the second tab 2b is made of the same material as the foil layer of the second electrode 11b.

[0043] For example, the first electrode sheet 11a is a positive electrode sheet, and the first electrode tab 2a connected to the first electrode sheet 11a is a positive electrode tab. The positive electrode tab is integrally formed with the positive electrode foil layer. For example, the second electrode sheet 11b is a negative electrode sheet, and the second electrode tab 2b connected to the negative electrode sheet is a negative electrode tab. The negative electrode tab is integrally formed with the negative electrode foil layer.

[0044] Furthermore, an adapter 3 is connected to the tab 2. The adapter 3 is used to connect to external components, thereby achieving electrical connection between the battery and external components (such as electrical equipment). The adapter 3 is typically sheet-shaped, and the material of the adapter 3 depends on the polarity of the tab 2. For example, when the tab 2 is a positive tab, the adapter 3 can be made of aluminum, an aluminum alloy, etc.; when the tab 2 is a negative tab, the adapter 3 can be made of copper, a copper alloy, nickel, etc.

[0045] The housing 4 is used to encapsulate the electrode assembly and electrolyte components. The housing 4 can be a steel shell, an aluminum shell, a plastic shell (such as polypropylene), a composite metal shell (such as a copper-aluminum composite shell), or an aluminum-plastic film.

[0046] The electrolyte plays a role in conducting ions between the positive and negative electrodes. This application has no specific restrictions on the type of electrolyte, and it can be selected according to needs.

[0047] Specifically, the battery comprises a housing 4, a cover plate, the electrode assembly, and an electrolyte. The housing 4 has a receiving cavity and an opening, the electrode assembly is received in the receiving cavity, and the cover plate is used to seal the opening of the housing 4.

[0048] Specifically, in some embodiments, Figure 1-Figure 3 and Figure 7 As shown, the tab 2 includes a bent portion 21 that bends toward the body 1 and extends along a first direction T. One end of the adapter 3 is connected to the bent portion 21, and the portion where the adapter 3 and the bent portion 21 are connected together forms a connecting segment 5. Specifically, the adapter 3 includes a first connecting portion 31 and a second connecting portion 32 that are connected and angled. The first connecting portion 31 is connected to the bent portion 21, and the portion where the first connecting portion 31 and the bent portion 21 are connected together forms a connecting segment 5. The connecting segment 5 includes a first connecting segment 51 and a second connecting segment 52.

[0049] Specifically, the tab 2 includes the first tab 2a and the second tab 2b. It is understood that both the first tab 2a and the second tab 2b have the aforementioned bent portion 21. The adapter 3 includes the first adapter 3a and the second adapter 3b. It is understood that both the first adapter 3a and the second adapter 3b have the aforementioned first connecting portion 31 and the second connecting portion 32.

[0050] Among them, such as Figure 7 As shown, one end of the first adapter 3a is connected to the bent portion 21 of the first tab 2a, and the portion where the first adapter 3a is connected to the bent portion 21 of the first tab 2a together forms the first connecting segment 51. Specifically, the first connecting portion 31 of the first adapter 3a is connected to the bent portion 21 of the first tab 2a, and the portion where the first connecting portion 31 of the first adapter 3a is connected to the bent portion 21 of the first tab 2a together forms the first connecting segment 51.

[0051] Among them, such as Figure 1 As shown, one end of the second adapter 3b is connected to the bent portion 21 of the second tab 2b, and the portion where the second adapter 3b is connected to the bent portion 21 of the second tab 2b together forms the second connecting segment 52. Specifically, the first connecting portion 31 of the second adapter 3b is connected to the bent portion 21 of the second tab 2b, and the portion where the first connecting portion 31 of the second adapter 3b is connected to the bent portion 21 of the second tab 2b together forms the second connecting segment 52.

[0052] In some embodiments, as Figure 1 As shown, along the second direction L, the distance between the second connecting segment 52 and the second pole piece 11b is L1 mm, and the tensile strength of the second pole tab 2b is x MPa. L1 satisfies: (x*0.001)^0.5+0.4 <L1<x*0.001+1.4。

[0053] After a large number of experimental verifications, when the distance L1 between the bent portion 21 of the second tab 2b and the second electrode plate 11b and the tensile strength of the second tab 2b satisfy the relationship of (x * 0.001)^0.5 + 0.4 < L1 < x * 0.001 + 1.4, the problem that the second tab 2b is easily torn when the battery drops can be effectively alleviated, thereby improving the fracture failure problem of the second tab 2b and greatly enhancing the safety of the battery. Through experimental verification, when L1 ≥ x * 0.001 + 1.4, that is, in this formula, when L1 is too large compared to x, the second tab 2b will shake or move during the drop; at this time, the second tab 2b is subjected to the pulling force of the second electrode plate 11b and the second adapter 3b and the stress of external impact, but the strength of the second tab 2b is insufficient to cope with the stress received, resulting in the problem of tab 2 tearing and reducing the battery safety. When L1 ≤ (x * 0.001)^0.5 + 0.4, that is, in this formula, when L1 is too small compared to x, during the drop process, the battery will be extruded by external forces, causing the distance between the bent portion 21 and the second electrode plate 11b to further decrease; at this time, although the strength of the second tab 2b is sufficient to cope with the stress received during the drop, the bent portion 21 or even the entire second tab 2b is likely to interfere with the electrode plate 11, resulting in the problem of the tab 2 being inserted backwards into the electrode plate 11 and reducing the battery safety.

[0054] Therefore, in the embodiments of the present invention, according to the tensile strength of the second tab 2b, the distance range between the bent portion 21 of the second tab 2b and the second electrode plate 11b is reasonably limited, which can not only alleviate the problem that the second tab 2b is easily torn during the drop, but also avoid the interference between the second tab 2b and the electrode plate 11, greatly improving the safety performance of the battery cell.

[0055] It can be understood that in this embodiment, L1 specifically refers to the distance between the surface of the second connecting segment 52 facing the body 1 and the second electrode plate 11b. For example, along the second direction L, the bent portion 21 of the second tab 2b is located on the side of the second adapter 3b close to the body 1. At this time, L1 specifically refers to the distance between the surface of the bent portion 21 of the second tab 2b facing the body 1 and the second electrode plate 11b. For example, along the second direction L, the second adapter 3b is located on the side of the bent portion 21 of the second tab 2b close to the body 1. At this time, L1 specifically refers to the distance between the surface of the second adapter 3b facing the body 1 and the second electrode plate 11b.

[0056] More specifically, in the first direction T, the distance between each position of the second connecting segment 52 and the second pole piece 11b along the second direction L is L1. Among them, in the first direction T, the distance L1 between different positions of the connecting segment 5 and the second pole piece 11b along the second direction L can be the same or different, as long as the relationship of (x * 0.001)^0.5 + 0.4 < L1 < x * 0.001 + 1.4 is satisfied.

[0057] For example, the tensile strength x of the second tab 2b is 300 MPa. At this time, 0.948 mm < L1 < 1.7 mm. The value of L1 can be 0.948 mm, 1.0 mm, 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm, 1.5 mm, 1.6 mm, 1.7 mm, etc.

[0058] For example, the tensile strength x of the second tab 2b is 400 MPa. At this time, 1.03 mm < L1 < 1.8 mm. The value of L1 can be 1.03 mm, 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm, 1.5 mm, 1.6 mm, 1.7 mm, 1.8 mm, etc.

[0059] For example, the tensile strength x of the second tab 2b is 520 MPa. At this time, 1.12 mm < L1 < 1.92 mm. The value of L1 can be 1.12 mm, 1.2 mm, 1.3 mm, 1.4 mm, 1.5 mm, 1.6 mm, 1.7 mm, 1.8 mm, 1.9 mm, 1.92 mm, etc.

[0060] For example, the tensile strength x of the second tab 2b is 600 MPa. At this time, 1.17 mm < L1 < 2 mm. The value of L1 can be 1.17 mm, 1.2 mm, 1.3 mm, 1.4 mm, 1.5 mm, 1.6 mm, 1.7 mm, 1.8 mm, 1.9 mm, 2 mm, etc.

[0061] This application does not specifically limit the value of the tensile strength x of the second tab 2b, which can be adjusted adaptively according to the performance of the battery as long as the application requirements of the battery are met.

[0062] In some embodiments, the first pole piece 11a can be a positive pole piece, and the first tab 2a can be a positive tab; the second pole piece 11b can be a negative pole piece, and the second tab 2b can be a negative tab.

[0063] In some embodiments, along the first direction T, the projected area of the first pole piece 11a is larger than that of the second pole piece 11b, that is, the edge of the first pole piece 11a protrudes beyond the second pole piece 11b. For example, the first pole piece 11a is a positive pole piece and the second pole piece 11b is a negative pole piece. That is, the edge of the negative pole piece protrudes beyond the positive pole piece. L1 specifically refers to the distance between the second connection segment 52 formed by the negative pole tab along the second direction L and the negative pole piece.

[0064] Since the edge of the negative pole piece protrudes beyond the positive pole piece, during a drop, the negative pole piece is first impacted, and the impact force is transmitted to the second connection segment 52. The negative pole piece is liable to break due to the reaction force from the second connection segment 52. The breakage of the negative pole piece will cause lithium deposition during the charge and discharge process of the battery, affecting the safety performance of the battery. That is, compared with the positive pole piece, the negative pole piece of the battery is more prone to tearing problems during a drop. Therefore, in this embodiment, by reasonably limiting the distance between the second connection segment 52 and the negative pole piece according to the tensile strength x of the second pole tab, that is, the negative pole tab, the problem that the negative pole tab is prone to tearing during a drop can be effectively alleviated, and further the problem that the pole tab of the battery is prone to fracture failure during a drop can be effectively alleviated. At the same time, by reasonably limiting the distance between the second connection segment 52 and the negative pole piece, interference between the second connection segment 52 and the negative pole piece can be avoided, further improving the safety performance of the battery.

[0065] It can be understood that the shapes and structures of the first pole tab 2a and the first adapter 3a are the same as those of the second pole tab 2b and the second adapter 3b. The distance between the first connection segment 51 formed by the first pole tab 2a and the first adapter 3a and the second pole piece 11b is L1'. Where L1' can also satisfy: (x * 0.001)^0.5 + 0.4 < L1' < x * 0.001 + 1.4. Where x is the tensile strength of the second pole tab 2b.

[0066] For the convenience of measurement, when the difference between the distance L1' between the first connection segment 51 and the second pole piece 11b and the distance L1 between the second connection segment 52 and the second pole piece 11b is less than or equal to 0.1 mm, the measured value of L1' can be equivalently used to replace the measured value of L1.

[0067] Furthermore, in some embodiments, as Figure 1 and Figure 6 shown, the battery includes the above-mentioned housing 4, and the body 1 and the pole tabs 2 are both located inside the housing 4. The second connection portion 32 extends along the second direction L, and at least part of the structure is located outside the housing 4. The housing 4 has a first sealing edge 41. Along the first direction T, the first sealing edge 41 is located on the side of the second connection portion 32 away from the first connection portion 31. As Figure 1As shown in FIG, the first edge seal 41 is located to the left of the second connecting section 52. Along the first direction T, the distance between the bent portion 21 of the second tab 2b and the first edge seal 41 is L2, where L2 satisfies the following conditions: 0.15 mm ≤ L2 ≤ 2 mm. Preferably, L2 satisfies the following conditions: 0.5 mm ≤ L2 ≤ 1.5 mm.

[0068] The tab 2 has a connecting portion and a bent portion 21 connected to each other, and the connecting portion is connected between the electrode 11 and the bent portion 21. L2 specifically refers to the distance along the first direction T between the end of the bent portion 21 of the second tab 2b away from the connecting portion and the surface of the first edge seal 41 facing the second connecting portion 32.

[0069] For example, L2 can be 0.15mm, 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, etc.

[0070] Since there is a spacing L2 between the bent portion 21 and the first edge seal 41 along the first direction T, the second pole tab 2b will move in the space formed by the spacing when it falls. If L2 is too large, the moving space is too large, the moving displacement of the second pole tab 2b is greater, the tensile stress on the second pole tab 2b is greater, and the second pole tab 2b is more likely to break. If L2 is too small, the second pole tab 2b is likely to interfere with the second adapter 3b, affecting the forming of the second adapter 3b. In this embodiment, L2 is reasonably controlled between 0.15 and 2 mm, which can not only avoid the moving space of the second pole tab 2b being too large, alleviate the problem of the pole tab 2 breaking, and improve the safety performance of the battery; but also avoid the interference between the second pole tab 2b and the second adapter 3b, and ensure the forming effect of the second adapter 3b.

[0071] It can be understood that along the first direction T, the distance between the bent portion 21 of the first tab 2a and the first edge seal 41 is L2', and L2' may also satisfy: 0.15mm≤L2'≤2mm. Preferably, L2' satisfies: 0.5mm≤L2'≤1.5mm. For example, L2' can be 0.15mm, 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, etc.

[0072] Similar to the limited range of L2, by reasonably controlling L2' between 0.15 and 2 mm, it is possible to avoid excessive movement space of the first tab 2a, alleviate the problem of tab 2 breakage, and improve the safety performance of the battery; it is also possible to avoid interference between the first tab 2a and the first adapter 3a, thereby ensuring the molding effect of the first adapter 3a.

[0073] Furthermore, in some embodiments, Figure 2-Figure 4 As shown, the first connecting portion 31 of the first adapter 3 a is welded to the bent portion 21 of the first tab 2 a , and a welding area 50 is formed on the first connecting section 51 .

[0074] Along the third direction W, the size of the welding area 50 of the first connecting section 51 is W1 mm, the size of the first connecting portion 31 of the first adapter 3 a is W2 mm, and W1 / W2 satisfies: 40%≤W1 / W2≤90%.

[0075] In this embodiment, by reasonably limiting the ratio range of W1 / W2 in the first connecting portion 31, it is possible to ensure the welding reliability of the bending portion 21 of the first pole tab 2a and the first connecting portion 31 of the first adapter 3a, and to avoid the welding area 50 occupying too large a proportion, so that the first pole tab 2a is damaged by welding, thereby alleviating the safety failure problem caused by the breakage of the first pole tab 2a during the falling process.

[0076] In some embodiments, the first connecting portion 31 of the second transition component 3 b is welded to the bent portion 21 of the second tab 2 b , and a welding area 50 is formed on the second connecting segment 52 .

[0077] Among them, such as Figure 4 As shown, along the third direction W, the size of the welding area 50 of the second connecting section 52 is W3 mm, the size of the first connecting portion 31 of the second adapter 3b is W4 mm, and W3 / W4 satisfies: 40%≤W3 / W4≤90%.

[0078] The third direction W is perpendicular to both the first direction T and the second direction L, and the third direction W can be understood as the width direction of the battery.

[0079] The present application does not specifically limit the shape of the welding area 50. The welding area 50 can be triangular, trapezoidal, rectangular, or other regular or irregular shapes, preferably rectangular. W1 and W3 specifically refer to the maximum dimensions of the welding area 50 along the third direction W.

[0080] For example, W1 / W2 may be 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, etc.

[0081] For example, W3 / W4 can be 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, etc.

[0082] In this embodiment, by reasonably limiting the ratio range of W3 / W4 in the second connecting section 52, it is possible to ensure the welding reliability of the bending portion 21 of the second pole tab 2b and the first connecting portion 31 of the second adapter 3b, and avoid the welding area 50 from occupying too large a proportion, which would cause welding damage to the second pole tab 2b, thereby alleviating the safety failure problem caused by the breakage of the second pole tab 2b during the falling process.

[0083] Furthermore, in some embodiments, the first electrode tab 2a is a positive electrode tab, and the second electrode tab 2b is a negative electrode tab. The ratio W1 / W2 in the first connecting section 51 is less than or equal to the ratio W3 / W4 in the second connecting section 52.

[0084] In this embodiment, the tab 2 in the first connecting section 51 is a positive tab. The first adapter 3a connected to the positive tab is typically made of the same material as the positive tab, such as aluminum. The tab 2 in the second connecting section 52 is a negative tab. The second adapter 3b connected to the negative tab is typically made of a different material than the negative tab, such as copper and nickel. Because the weld strength between structures made of the same material is greater than that between structures made of different materials, the weld strength between the positive tab and the first adapter 3a is often greater than the weld strength between the negative tab and the second adapter 3b. By making the ratio of W1 / W2 in the first connecting segment 51 less than or equal to the ratio of W3 / W4 in the second connecting segment 52, the present invention can further reduce the size of the welding area 50 on the first connecting segment 51 within a reasonable range, so that the positive electrode ear and the first adapter 3a have sufficient welding strength while reducing the damage to the positive electrode ear caused by welding, thereby further alleviating the problem of the positive electrode ear falling and breaking failure.

[0085] Preferably, in the first connecting segment 51, W1 / W2 satisfies the following: 40% ≤ W1 / W2 ≤ 80%. For example, in the first connecting segment 51, W1 / W2 can be 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, etc. In this embodiment, by reasonably limiting the range of the W1 / W2 ratio in the first connecting segment 51, the reliability of the welding between the positive electrode tab and the first adapter 3a is ensured while preventing the welding area 50 from being too large, which could damage the positive electrode tab. This, in turn, mitigates the safety failure issue caused by the positive electrode tab breaking during a drop.

[0086] Preferably, in the second connecting segment 52, W3 / W4 satisfies the following: 50% ≤ W3 / W4 ≤ 90%. For example, in the second connecting segment 52, W3 / W4 can be 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, etc. In this embodiment, by reasonably limiting the range of the W3 / W4 ratio in the second connecting segment 52, the reliability of the welding between the negative electrode tab and the second adapter 3b can be ensured while preventing the welding area 50 from being too large, which could damage the negative electrode tab. This can further alleviate the safety failure caused by the negative electrode tab breaking during a drop.

[0087] It can be understood that there are multiple positive and negative electrode sheets, and accordingly, there are multiple positive tabs connected to the positive electrode sheets, and multiple negative tabs connected to the negative electrode sheets. In actual production, multiple positive tabs are usually pre-welded into an integral structure, and then the integral structure formed by the multiple positive tabs is welded to the first adapter 3a for a second time. After the multiple negative tabs are pre-welded into an integral structure, the integral structure formed by the multiple negative tabs is welded to the second adapter 3b for a second time. On the first connecting section 51 and the second connecting section 52 formed in this way, in the welding area 50, the welds 501 formed by pre-welding and the welds formed by secondary welding often overlap, and excessively dense welds 501 can easily damage the electrode 11 and the adapter 3.

[0088] In the present application, in some embodiments, the welding area 50 is provided with a plurality of welding points 501, and each welding point 501 is arranged at intervals. That is, in the first direction T, the projections of adjacent welding points 501 do not overlap. In this example, by arranging the welding points 501 in the welding area 50 at intervals, the damage to the tab 2 and the adapter plate caused by welding can be reduced, the strength of the tab 2 and the adapter plate can be ensured, and the situation where the tab 2 is torn due to insufficient strength, or the adapter plate is to be broken due to insufficient strength, etc., can be reduced, thereby further improving the safety performance of the battery. It can be understood that the welding area 50 of this embodiment can be a welding area on the first connecting section 51 or a welding area on the second connecting section 52. Preferably, the multiple welding points 501 on the welding area of ​​the first connecting section 51 and the multiple welding points 501 on the welding area of ​​the second connecting section 52 are all arranged at intervals.

[0089] In the embodiments of the present application, the pre-welding step can be omitted during actual production, and multiple positive electrode sheets can be directly welded to the first adapter 3a in a single process, while multiple negative electrode sheets can be directly welded to the second adapter 3b in a single process. In the first connecting segment 51 and the second connecting segment 52 thus formed, the weld points 501 on the welding area 50 can be spaced apart, ensuring that the tab 2 between adjacent weld points 501 in the welding area 50 is intact, further ensuring the inherent strength of the tab 2.

[0090] Preferably, the number of weld points 501 in the first connecting segment 51 is less than or equal to the number of weld points 501 in the second connecting segment 52. As previously mentioned, the positive tab and the first adapter 3a are typically made of the same material, while the negative tab and the second adapter 3b are typically made of a different material. This results in the weld strength of the first connecting segment 51 often being greater than the weld strength of the second connecting segment 52. In this embodiment, by appropriately reducing the number of weld points 501 in the first connecting segment 51, damage to the positive tab can be reduced while ensuring good welding quality, alleviating the problem of the positive tab being prone to breakage and failure when dropped, further improving battery safety.

[0091] Preferably, if Figure 4 As shown, along the third direction W, the spacing between two adjacent welding points 501 is L3, and L3 satisfies: 0.1mm≤L3≤0.5mm. For example, L3 can be 0.1mm, 0.15mm, 0.2mm, 0.25mm, 0.3mm, 0.35mm, 0.4mm, 0.45mm, 0.5mm, etc. In this embodiment, by reasonably limiting the spacing range of adjacent welding points 501 in the third direction W, it is possible to avoid the welding points 501 being too sparse to affect the welding effect, thereby ensuring the welding strength between the tab 2 and the adapter 3; it is also possible to avoid the welding points 501 being too dense to cause damage to the tab 2 or the adapter 3, thereby ensuring the strength of the connecting section 5, and avoiding the welding area 50 from becoming a weak point that is fractured by stress, thereby improving the safety performance of the battery.

[0092] Preferably, along the second direction L, the spacing between two adjacent welding points 501 is L4, and L4 satisfies: 0.1mm≤L4≤0.5mm. For example, L4 can be 0.1mm, 0.15mm, 0.2mm, 0.25mm, 0.3mm, 0.35mm, 0.4mm, 0.45mm, 0.5mm, etc. Similarly, in this embodiment, by reasonably limiting the spacing range of adjacent welding points 501 in the second direction L, it is possible to avoid the welding points 501 being too sparse to affect the welding effect, thereby ensuring the welding strength between the tab 2 and the adapter 3; it is also possible to avoid the welding points 501 being too dense to cause damage to the tab 2 or the adapter 3, thereby ensuring the strength of the connecting section 5, and avoiding the welding area 50 from becoming a weak point that is fractured by stress, thereby improving the safety performance of the battery.

[0093] Furthermore, in some embodiments, the battery includes the above-mentioned electrolyte, and the electrolyte includes fluoroethylene carbonate. Fluoroethylene carbonate is a commonly used electrolyte film-forming additive, mainly used to improve the cycle life and high-temperature performance of the battery. Fluoroethylene carbonate will form a stable solid electrolyte interface film (SEI film) on the surface of the negative electrode during the first charge and discharge process of the battery, thereby reducing the corrosion of the negative electrode and improving the cycle stability of the battery. However, the tab 2 and the adapter 3 are more sensitive to fluorides, and the decomposition products of fluoroethylene carbonate (such as HF) may react with the tab 2 and the adapter 3, resulting in corrosion of the tab 2 and the adapter 3. This corrosion is particularly obvious in the welding area 50 of the second connecting section 52, which may affect the conductivity and mechanical strength of the second tab 2b and reduce the reliability of the welding between the second tab 2b and the second adapter 3b. Especially under high temperature or high current density conditions, the greater the requirement for welding strength.

[0094] The content of fluoroethylene carbonate in the electrolyte is f%, and the value range of f% is usually 5%-20%. The sum of the areas of the welding points 501 in the welding area 50 of the second connecting section 52 is S mm 2 , S satisfies the following: 0.5*f+4≤S≤3*f+4. Experimental verification has shown that if S is less than 0.5*f+4, meaning that S is too small compared to f, the weld strength between the second tab 2b and the second adapter 3b is insufficient, making it easy for the second tab 2b to fall off. If S is greater than 3*f+4, meaning that S is too large compared to f, excessive side reactions can occur, leading to corrosion of the second tab 2b in the weld area 50, reducing the strength of the second tab 2b and making it more likely to break and fail when dropped, thus affecting the safety performance of the battery.

[0095] Taking the content of fluoroethylene carbonate in the electrolyte as 6% as an example, at this time, the sum of the areas S of the welding points 501 in the welding area 50 should meet the following requirements: 7mm 2 ≤S≤22mm 2 For example, S can be 7mm 2 , 8mm 2 , 9mm 2 , 10mm 2 , 11mm 2 , 12mm 2 , 13mm 2 , 14mm 2 , 15mm 2 , 16mm 2 , 17mm 2 , 18mm 2 , 19mm 2 , 20mm 2 , 21mm 2 , 22mm 2 wait.

[0096] Taking the content of fluoroethylene carbonate in the electrolyte as 8% as an example, at this time, the sum of the areas S of the welding points 501 in the welding area 50 should meet the following requirements: 8mm 2 ≤S≤28mm 2 For example, S can be 8mm 2 , 9mm 2 , 10mm 2 , 11mm 2 , 12mm 2 , 13mm 2 , 14mm 2 , 15mm 2 , 16mm 2 , 17mm 2 , 18mm 2 , 19mm 2 , 20mm 2 , 21mm 2 , 22mm 2 , 23mm 2 , 24mm 2 , 25mm 2 , 26mm 2 , 27mm 2 , 28mm 2 wait.

[0097] Taking the content of fluoroethylene carbonate in the electrolyte as 10% as an example, at this time, the sum of the areas S of the welding points 501 in the welding area 50 should meet the following requirements: 9mm 2 ≤S≤34mm 2 For example, S can be 9mm 2 , 10mm 2 , 11mm 2 , 12mm 2 , 13mm 2 , 14mm 2 , 15mm 2 , 16mm 2 , 17mm 2 , 18mm 2 , 19mm 2 , 20mm 2 , 21mm 2 , 22mm 2 , 23mm 2 , 24mm 2 , 25mm 2 , 26mm 2 , 27mm 2 , 28mm 2 , 29mm 2 , 30mm 2 , 31mm2 , 32mm 2 , 33mm 2 , 34mm 2 wait.

[0098] Furthermore, if Figure 6 As shown, the body 1 has a first edge 13 and two second edges 14. The first edge 13 is formed at one end of the body 1 away from the tab 2 along the second direction L. Two second edges 14 are formed on both sides of the body 1 along the third direction W.

[0099] In some embodiments, along the second direction L, the distance between the first edge 13 and the housing 4 is L5, and L5 satisfies the following: 0.2mm≤L5≤1.2mm. For example, L5 can be 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm, 1.1mm, 1.2mm, etc. If L5 is too large, the movable space of the body 1 during the drop process is also large, and the stress on the tab 2 during the drop is also large, which can easily cause the tab 2 to break and fail. During the battery cycle, the body 1 will expand to a certain extent. If L5 is too small, the pole piece 11 is likely to interfere with the housing 4 during the battery cycle, resulting in a constant interaction force between the pole piece 11 and the housing 4. Over time, this can cause damage to the housing 4 and reduce the battery life. This embodiment reasonably controls the value range of L5, so that the movable space of the main body 1 in the shell 4 is reasonable, avoiding excessive stress on the tab 2 when it falls and causing fracture failure, thereby improving the safety of the battery; and avoiding interference between the main body 1 and the shell 4 during the battery cycle, thereby ensuring the service life of the battery.

[0100] In some embodiments, along the third direction W, the distance between the second edge 14 and the shell 4 is L6, and L6 satisfies: 0≤L6≤1mm. For example, L5 can be 0.01mm, 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm, etc. Similarly, this embodiment reasonably controls the value range of L6, thereby ensuring a reasonable movable space for the body 1 within the shell 4, preventing the tab 2 from being subjected to excessive stress and causing fracture failure when it falls, thereby improving the safety of the battery; and preventing interference between the body 1 and the shell 4 during the battery cycle, thereby ensuring the service life of the battery.

[0101] Furthermore, in some embodiments, Figure 2 、 Figure 3 and Figure 5As shown, the body 1 has a first surface 15 and a second surface 16 arranged opposite each other along a first direction T, and a side surface 17 connecting the first surface 15 and the second surface 16. Adhesive tape 18 is provided along the edge of the body 1. Along the width direction R of the adhesive tape, the adhesive tape 18 sequentially covers at least part of the first surface 15, the side surface 17, and the second surface 16. The adhesive tape 18 can be provided on both the first edge 13 and / or the second edge 14 of the body 1. Preferably, the adhesive tape 18 is provided on both the first edge 13 and both second edges 14 of the body 1.

[0102] Along the width direction R of the adhesive tape, the dimension of the adhesive tape 18 is a mm. The dimension of the portion of the adhesive tape 18 covering the first surface 15 is b mm. The dimension of the portion of the adhesive tape 18 covering the second surface 16 is c mm. When the battery is at a 100% SOC (State of Charge), the vertical distance between the first surface 15 and the second surface 16 along the first direction T is d mm. Here, ΔL = abcd, where ΔL satisfies the following: 0.3 mm ≤ ΔL ≤ 2 mm.

[0103] For example, ΔL may be 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1.0 mm, 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm, 1.5 mm, 1.6 mm, 1.7 mm, 1.8 mm, 1.9 mm, 2 mm, etc.

[0104] When adhesive tape 18 is applied to body 1, a margin is typically left between adhesive tape 18 and side surface 17 of body 1. This results in a width a of adhesive tape 18 being greater than the sum of dimension b of the portion of adhesive tape 18 covering first surface 15, dimension c of the portion of adhesive tape 18 covering second surface 16, and the perpendicular distance d between first surface 15 and second surface 16 along first direction T. This means that ΔL is greater than 0. ΔL can be understood as the tightness of adhesive tape 18 applied to body 1.

[0105] If the value of ΔL is too large, that is, the tightness of the adhesive is too large, the movable space of the main body 1 will become larger, making the stress distribution of the main body 1 uneven during the falling process, which may easily cause the pole piece 11 to be dislocated, and then cause the problem of the tab 2 being stretched and broken. If the value of L is too small, that is, the tightness of the adhesive is too small, during the battery cycle, due to the expansion of the main body 1, it is easy to cause the edge of the pole piece 11 to cut the adhesive paper 18, affecting the integrity of the main body 1, which may also cause the pole piece 11 to be dislocated, and then cause the tab 2 to be stretched and broken. In this embodiment, by reasonably controlling the value of ΔL, it is possible to avoid the movable space of the main body 1 being too large, ensure the uniformity of the stress distribution of the main body 1 when falling, and avoid the pole piece 11 cutting the adhesive paper 18 during the battery cycle, ensure the integrity of the main body 1, and then fully ensure the reliability of the tab 2, alleviate the problem of the tab 2 being broken and failing when falling, and improve the safety of the battery.

[0106] The technical effects of the present invention are illustrated below with reference to Comparative Examples 1-7 and Examples 1-38.

[0107] Among them, Comparative Examples 1-7 and Examples 1-38 all have the following preparation steps:

[0108] Step 1: Prepare the positive electrode active material layer slurry, coat the positive electrode active material on the surface of the aluminum foil, and obtain the positive electrode sheet through baking, rolling and cutting.

[0109] The preparation method of the positive electrode active material layer provided in this embodiment is as follows: after the conductive agent and PVDF glue are mixed evenly, lithium cobalt oxide is added and stirred evenly to obtain a slurry of the positive electrode active material layer.

[0110] The positive electrode active material layer is composed of 97.6% by mass of lithium cobalt oxide, 1.05% by mass of PVDF, and 1.35% by mass of a conductive agent, wherein the conductive agent is composed of conductive carbon black, single-walled carbon nanotubes, and multi-walled carbon nanotubes.

[0111] Step 2: Prepare the negative electrode active material layer slurry, apply the negative electrode active material layer slurry on the carbon-coated copper foil, and obtain the negative electrode sheet through baking, rolling and slitting.

[0112] Among them, the preparation method of the negative electrode active material layer is as follows: 0.5% by mass of a conductive agent and 97% by mass of graphite powder are mixed evenly, and then deionized water, 1.3% by mass of carboxymethyl cellulose and 1.2% by mass of styrene-butadiene rubber adhesive are added respectively and stirred evenly to obtain a negative electrode active material layer slurry.

[0113] Step 3: The positive electrode sheet and the negative electrode sheet are die-cut and stacked to obtain a stacked core, which is the above-mentioned main body 1.

[0114] Step 4: The aluminum-plastic film is punched through a step mold core to obtain the above-mentioned shell 4.

[0115] Step 5: After the body 1 is placed in the shell 4, the lithium-ion battery is obtained by packaging, baking, liquid injection, formation, sorting, secondary sealing, OCV and packaging.

[0116] Step 6: Perform a drum drop test on the lithium-ion battery. During the drum drop test, the lithium battery is at 100% SOC.

[0117] The thickness of the shell 4 is 50-200 μm.

[0118] The active material of the positive electrode active material layer includes one or more of lithium cobalt oxide, lithium iron phosphate, nickel cobalt manganese lithium, nickel cobalt aluminum lithium, lithium manganese oxide and lithium-rich manganese-based lithium.

[0119] The negative electrode active material layer includes, but is not limited to, one or more of natural graphite, artificial graphite, mesophase carbon microbeads, lithium titanate, silicon negative electrode, silicon-carbon negative electrode and alloy negative electrode.

[0120] Among them, the positive electrode adhesive is mainly polyvinylidene fluoride (PVDF) adhesive, and the negative electrode adhesive is mainly styrene-butadiene rubber.

[0121] The conductive agent includes at least one of conductive carbon black, Ketjen black, single-walled carbon nanotubes, and multi-walled carbon nanotubes.

[0122] The drum drop test method is as follows: the battery is charged at room temperature using a constant current and voltage of 0.5C to the charge limit voltage. A dedicated battery drum drop test fixture is used to perform a drum drop test, dropping the battery from a height of 1m at a speed of 5 cycles / min for 306 cycles (two drops constitute one cycle). After 306 cycles, the battery cell is inspected for damage and leakage, and the open-circuit voltage is measured. The battery is then charged at room temperature using a constant current and voltage of 0.2C to the limit voltage. The battery tab condition and tab inversion status are then tested using a CT scan. The battery is then disassembled to confirm tab breakage.

[0123] The tab failure ratio is determined as follows: 10 batteries are grouped together, and if at least one second tab in each battery breaks, the tab failure is determined for that battery. The tab failure ratio is calculated by taking the ratio of the number of batteries with tab failures to the median number of batteries (10). Specifically, in the comparative examples and examples, the tab failure ratio refers to the failure ratio of the second tab 2b.

[0124] The method for determining whether a tab is inverted is as follows: if part of the tab structure is invertedly inserted into the electrode sheet, it is determined to be inverted; otherwise, it is determined to be not inverted. The inverted tab insertion condition can be directly determined based on the image information of the CT test. Specifically, in each comparative example and each embodiment, the inverted tab insertion condition specifically refers to the inverted insertion condition of the second tab 2b.

[0125] The method for judging the welding condition of the adapter and the tab is as follows: after disassembly, the residual area ratio of the welding between the adapter and the tab is obtained based on the image information of the CT test. The residual area ratio refers to the percentage of the welding area between the adapter and the tab in the welding area after the drop test to the welding area between the adapter and the tab before the drop test. If the adapter and the tab are spot welded, the welding area refers to the area of ​​the weld point between the adapter and the tab. If the residual area ratio is less than 30% but greater than 0%, it is determined to be tab damage; if the residual area ratio is 0, that is, the adapter and the tab are separated, it is determined to be tab detachment; according to the image information of the CT test, if the welding area appears gray-black, rust spots or oxide deposition, etc., and the residual area ratio is less than 100%, it is determined to be corrosion of the welding area. Specifically, in each comparative example and each embodiment, the welding condition of the adapter and the tab specifically refers to the welding condition of the second adapter 3b and the second tab 2b.

[0126] The adapter's forming condition is determined by examining the battery's appearance to determine whether the second connecting portion 32 of the adapter 3 can bend normally. If so, it is considered normal; if not, it is determined to be interference between the tab and the adapter. Interference specifically refers to the spacing between the tab and the adapter along the first direction being too small, causing the tab to affect the adapter's bending, resulting in the adapter's inability to bend and form. Specifically, in the comparative examples and embodiments, the adapter's forming condition refers specifically to the forming condition of the second adapter 3b.

[0127] The method for judging whether the adhesive tape is broken is as follows: if any adhesive tape on the battery body is broken, it is determined to be a broken adhesive tape; if no adhesive tape on the battery body is broken, it is determined to be no broken adhesive tape.

[0128] The difference between Comparative Examples 1-7 and Examples 1-38 lies in the different specific data of the above parameters, that is, the specific values ​​of L1, L2, the ratio of W3 / W4, S, L5, L6, and ΔL. The specific values ​​and experimental results of each comparative example are shown in Table 1:

[0129]

[0130]

[0131]

[0132] Table 1

[0133] Among them, the tensile strength x in Table 1 is specifically the tensile strength of the negative electrode tab. L1 is the distance between the second connecting section 52 and the negative electrode sheet in the second direction L. L2 is the distance between the bent portion 21 of the negative electrode sheet and the first sealing edge 41 in the third direction W. W3 / W4 is the ratio of the dimension of the welding area 50 of the second connecting section 52 in the third direction W to the dimension of the first connecting portion 31 of the second adapter 3b in the third direction W. S is the sum of the areas of the welding spots 501 in the welding area 50 of the second connecting section 52.

[0134] From the experimental results of each embodiment and comparative example in Table 1, when L1 satisfies: (x * 0.001)^0.5 + 0.4 < L1 < x * 0.001 + 1.4, the problem that the negative electrode tab is easily torn when the battery drops can be effectively alleviated, thereby improving the fracture failure problem of the negative electrode tab and greatly enhancing the safety of the battery.

[0135] Furthermore, when the battery meets the range of each parameter, the failure problem of battery drop can be further improved, and the safety performance of the battery can be enhanced.

[0136] According to an embodiment of the present invention, on the other hand, an electrical device is also provided, including the battery as described above. The battery is used to provide electrical energy for the electrical device. The electrical device of the present invention includes the battery of the present invention, so it has the same technical effects as the battery of the present invention, which will not be elaborated here.

[0137] The electrical device of the present invention can be any device using a battery. For example, the electrical device can be a vehicle, a mobile phone, a portable device, a laptop computer, a ship, a spacecraft, an electric toy, and an electric tool, etc. The vehicle can be a fuel vehicle, a gas vehicle, or a new energy vehicle. The new energy vehicle can be a pure electric vehicle, a hybrid electric vehicle, or an extended-range electric vehicle, etc.; the spacecraft includes an airplane, a rocket, a space shuttle, and a spaceship, etc.; the electric toy includes a fixed or mobile electric toy. For example, a game console, an electric vehicle toy, an electric ship toy, and an electric airplane toy, etc.; the electric tool includes a metal cutting electric tool, a grinding electric tool, an assembly electric tool, and a railway electric tool. For example, an electric drill, an electric grinding wheel, an electric wrench, an electric screwdriver, a hammer drill, an impact electric drill, a concrete vibrator, and a planer, etc. The embodiments of the present application do not impose special restrictions on the above electrical devices.

[0138] Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A battery, characterized in that: An electrode assembly is included, the electrode assembly comprising: A body (1), the body (1) comprising a plurality of first pole pieces (11a), a plurality of second pole pieces (11b) and a plurality of diaphragms (12) stacked along a first direction (T); the first pole pieces (11a) and the second pole pieces (11b) have opposite polarities, the first pole pieces (11a) and the second pole pieces (11b) are alternately arranged along the first direction (T), and the diaphragm (12) is arranged between adjacent first pole pieces (11a) and second pole pieces (11b); A pole lug (2), comprising a second pole lug (2b); the second pole lug (2b) is connected to one side of the second pole piece (11b) along the second direction (L); the pole lug (2) comprises a bending portion (21), the bending portion (21) is bent toward the body (1) and extends along the first direction (T); The adapter (3) comprises a second adapter (3b); one end of the second adapter (3b) is connected to the bent portion (21) of the second pole tab (2b), and the portion where the second adapter (3b) is connected to the bent portion (21) of the second pole tab (2b) together forms a second connecting section (52); Along the second direction (L), the distance between the second connecting section (52) and the second pole piece (11b) is L1 mm, the tensile strength of the second pole tab (2b) is x MPa, and L1 satisfies: (x*0.001)^0.5+0.4 <L1<x*0.001+1.4; The first direction (T) is perpendicular to the second direction (L).

2. The battery according to claim 1, characterized in that The first pole piece (11a) is a positive pole piece, and the second pole piece (11b) is a negative pole piece; And / or, along the first direction (T), the projected area of ​​the second pole piece (11b) is larger than the projected area of ​​the first pole piece (11a).

3. The battery according to claim 1, characterized in that The battery comprises a shell (4), wherein the body (1) and the tab (2) are both located in the shell (4); The adapter (3) comprises a first connecting portion (31) and a second connecting portion (32) which are connected and form an angle; the first connecting portion (31) of the second adapter (3b) is connected to the bent portion (21) of the second pole tab (2b), and the portion where the first connecting portion (31) of the second adapter (3b) is connected to the bent portion (21) of the second pole tab (2b) together forms the second connecting section (52); the second connecting portion (32) extends along the second direction (L), and at least part of the structure is located outside the housing (4); The housing (4) has a first sealing edge (41); along the first direction (T), the first sealing edge (41) is located on a side of the second connecting portion (32) away from the first connecting portion (31); Along the first direction (T), the distance between the bent portion (21) of the second tab (2b) and the first edge seal (41) is L2, and L2 satisfies: 0.15 mm ≤ L2 ≤ 2 mm.

4. The battery according to claim 3, characterized in that The pole tab (2) includes a first pole tab (2a), and the first pole tab (2a) is connected to one side of the first pole piece (11a) along the second direction (L); the adapter (3) includes a first adapter (3a); The first connecting portion (31) of the first adapter (3a) is connected to the bent portion (21) of the first tab (2a), and the portion where the first connecting portion (31) of the first adapter (3a) is connected to the bent portion (21) of the first tab (2a) together forms a first connecting segment (51); The first connecting portion (31) of the first adapter (3a) is welded to the bent portion (21) of the first tab (2a), and a welding area (50) is formed on the first connecting section (51); Along the third direction (W), the size of the welding area (50) of the first connecting section (51) is W1 mm, the size of the first connecting portion (31) of the first adapter (3a) is W2 mm, and W1 / W2 satisfies: 40%≤W1 / W2≤90%; and / or, The first connecting portion (31) of the second adapter (3b) is welded to the bent portion (21) of the second tab (2b), and a welding area (50) is formed on the second connecting section (52); Along the third direction (W), the size of the welding area (50) of the second connecting section (52) is W3 mm, the size of the first connecting portion (31) of the second adapter (3b) is W4 mm, and W3 / W4 satisfies: 40%≤W3 / W4≤90%; The third direction (W) is perpendicular to both the first direction (T) and the second direction (L).

5. The battery according to claim 4, characterized in that The first electrode tab (2a) is a positive electrode tab, and the second electrode tab (2b) is a negative electrode tab; the ratio of W1 / W2 in the first connecting section (51) is less than or equal to the ratio of W3 / W4 in the second connecting section (52); Preferably, in the first connecting section (51), W1 / W2 satisfies: 40%≤W1 / W2≤80%; Preferably, in the second connecting section (52), W3 / W4 satisfies: 50%≤W3 / W4≤90%.

6. The battery according to claim 4, characterized in that The welding area (50) is provided with a plurality of welding points (501), and the welding points (501) are arranged at intervals; Preferably, the number of the welding points (501) of the first connecting section (51) is less than or equal to the number of the welding points (501) of the second connecting section (52); Preferably, along the third direction (W), the distance between two adjacent welding points (501) is L3, and L3 satisfies: 0.1mm≤L3≤0.5mm; Preferably, along the second direction (L), the distance between two adjacent welding points (501) is L4, and L4 satisfies: 0.1mm≤L4≤0.5mm.

7. The battery according to claim 6, characterized in that The battery comprises an electrolyte, the electrolyte comprises fluoroethylene carbonate, and the content of the fluoroethylene carbonate in the electrolyte is f%. The sum of the areas of the welding points (501) in the welding region (50) of the second connecting section (52) is S mm. 2 , S satisfies: 0.5*f+4≤S≤3*f+4.

8. The battery according to any one of claims 3 to 7, characterized in that The body (1) has a first edge (13) and two second edges (14); along the second direction (L), the first edge (13) is formed at one end of the body (1) away from the tab (2); along the third direction (W), two second edges (14) are formed on both sides of the body (1); Along the second direction (L), the distance between the first edge (13) and the housing (4) is L5, and L5 satisfies: 0.2 mm ≤ L5 ≤ 1.2 mm; and / or, Along the third direction (W), the distance between the second edge (14) and the housing (4) is L6, and L6 satisfies: 0≤L6≤1mm; The third direction (W) is perpendicular to both the first direction (T) and the second direction (L).

9. The battery according to any one of claims 1 to 7, characterized in that The body (1) comprises a first surface (15) and a second surface (16) arranged opposite to each other along the first direction (T), and a side surface (17) connected between the first surface (15) and the second surface (16); an adhesive tape (18) is provided on the edge of the body (1), and along the width direction (R) of the adhesive tape, the adhesive tape (18) sequentially covers at least part of the structure of the first surface (15), the side surface (17) and the second surface (16); Along the width direction (R) of the adhesive tape, the size of the adhesive tape (18) is a mm, the size of the portion of the adhesive tape (18) covering the first surface (15) is b mm, and the size of the portion of the adhesive tape (18) covering the second surface (16) is c mm; when the battery is in a 100% SOC state, along the first direction (T), the vertical distance between the first surface (15) and the second surface (16) is d mm; Among them, ΔL=abcd, ΔL satisfies: 0.3mm≤ΔL≤2mm.

10. An electrical device, characterized in that: include: The battery according to any one of claims 1 to 9.

Images