Battery and battery device

Abstract

The application relates to the technical field of batteries, and discloses a battery and a battery device, which comprise a battery core formed by winding a positive electrode sheet, a diaphragm and a negative electrode sheet, at least one of the positive electrode sheet and the negative electrode sheet is provided with a protective layer, the electrode sheet is bent to form a corner section, the corner section is provided with a plurality of layers in a laminated mode, and the protective layer is arranged on at least part of at least one layer of the corner section; the proportion of the number of layers of the protective layer on the plurality of layers of the corner section is k, the distance between the starting end of the electrode sheet and the adjacent protective layer is L, the electrode sheet comprises a current collector and an active material layer arranged on at least one surface of the current collector along the thickness direction of the current collector, the thickness of the current collector is d, and the following conditions are met: 1.6*10 ‑3 ≤k / (L×d)≤750*10 ‑3 The application can guarantee the protection effect of the protective layer on the active material layer, avoid material falling of the active material layer, improve the transmission efficiency of lithium ions, reduce the risk of lithium precipitation, further reduce the risk of battery short circuit, and improve the safety performance of the battery.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and more specifically to batteries and battery devices. Background Technology

[0002] For wound battery cells, a protective layer is usually placed on the bent section of the electrode to prevent electrode shedding. However, adding a protective layer can exacerbate lithium plating problems and pose a risk of lithium dendrites piercing the separator, leading to safety issues such as battery short circuits. Summary of the Invention

[0003] This invention provides a battery and battery device to solve the problem of increased lithium plating in existing batteries, which poses a risk of lithium dendrites piercing the separator and causing a short circuit.

[0004] In a first aspect, the present invention provides a battery comprising:

[0005] Housing assembly;

[0006] A battery cell, disposed within the housing assembly, is formed by winding a positive electrode, a separator, and a negative electrode that are stacked together. At least one of the positive and negative electrodes has a protective layer. The electrode is bent to form a corner segment, which is stacked in several layers. The protective layer is located between the electrode and the separator and is disposed on at least a portion of at least one layer of the corner segment. The proportion of the number of protective layers on the several layers of the corner segment is k. Along the length direction of the electrode, the distance between the starting end of the electrode and the adjacent protective layer is L mm. The electrode includes a current collector and an active material layer disposed on at least one side of the current collector along its thickness direction. The thickness of the current collector is d mm, satisfying 1.6 × 10⁻⁶ mm. -3 ≤k / (L×d)≤750×10 -3 .

[0007] Beneficial effects: By limiting the value of k / (L×d), the protective effect of the protective layer on the active material layer is guaranteed, and the loss of active material layer is prevented. At the same time, the lithium ion transport efficiency is improved, the risk of lithium plating is reduced, and the risk of battery short circuit is reduced, thereby improving battery safety performance.

[0008] Secondly, the present invention also provides a battery device comprising: the battery described above. Attached Figure Description

[0009] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0010] Figure 1 This is a schematic diagram of a structure in which a protective layer is provided on several corner segments according to an embodiment of the present invention;

[0011] Figure 2 This is a front view of the electrode and protective layer in the unfolded state according to an embodiment of the present invention;

[0012] Figure 3 This is a schematic diagram of the structure of a current collector and an active material layer according to an embodiment of the present invention;

[0013] Figure 4 This is a schematic diagram of another current collector and active material layer according to an embodiment of the present invention;

[0014] Figure 5 This is a schematic diagram of the structure of another current collector and active material layer according to an embodiment of the present invention;

[0015] Figure 6 This is a front view of the main body and current lead-out portion according to an embodiment of the present invention;

[0016] Figure 7 This is a schematic diagram of the first positional relationship between the protective layer and the current lead-out portion according to an embodiment of the present invention;

[0017] Figure 8 for Figure 7 A front view of the electrode and protective layer in the unfolded state;

[0018] Figure 9 This is a schematic diagram illustrating a second positional relationship between the protective layer and the current lead-out portion in an embodiment of the present invention.

[0019] Figure 10 for Figure 9 A front view of the electrode and protective layer in the unfolded state;

[0020] Figure 11 This is a schematic diagram of another current lead-out section according to an embodiment of the present invention;

[0021] Figure 12 This is a front view of the protective layer extending beyond the edge of the main body in an embodiment of the present invention.

[0022] Figure 13 This is a front view of an embodiment of the invention where the end of the protective layer does not extend beyond the edge of the main body.

[0023] Figure 14 This is a front view of an embodiment of the present invention, showing the end of the protective layer extending beyond the edge of the main body but not beyond the edge of the diaphragm.

[0024] Figure 15 This is a front view of the protective layer extending beyond the edge of the diaphragm in an embodiment of the present invention;

[0025] Figure 16 This is a schematic diagram of the protective layer extending to the horizontal section according to an embodiment of the present invention;

[0026] Figure 17 This is a schematic diagram of the structure of a protective layer according to an embodiment of the present invention;

[0027] Figure 18 This is a schematic diagram of another protective layer structure according to an embodiment of the present invention;

[0028] Figure 19 This is a schematic diagram of the battery cell structure according to an embodiment of the present invention;

[0029] Figure 20 This is a schematic cross-sectional view of the battery cell in an embodiment of the present invention, in the direction perpendicular to the width of the electrode sheet;

[0030] Figure 21 This is a schematic diagram of the battery explosion according to an embodiment of the present invention;

[0031] Figure 22 This is a schematic diagram of the crease and protective layer at the corner section in an embodiment of the present invention.

[0032] Explanation of reference numerals in the attached figures:

[0033] 1. Electrode; 11. Corner section; 111. Crease; 12. Starting end; 13. Current collector; 131. Main body; 132. Current lead-out section; 14. Active material layer; 141. Body area; 142. Thinning area; 15. Horizontal section; 2. Protective layer; 21. Base layer; 211. Through hole; 22. Adhesive layer; 221. Blank area; 222. Adhesive area; 3. Separator;

[0034] 10. Battery cell; 110. Bending area; 120. Straight area; 20. Housing assembly. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] The following is combined Figures 1 to 22 The following describes embodiments of the present invention.

[0037] According to an embodiment of the present invention, a battery is provided, comprising: a casing assembly; and a battery cell 10 disposed within the casing assembly. The battery cell 10 is formed by winding a positive electrode, a separator 3, and a negative electrode that are stacked together. At least one of the positive and negative electrode plates 1 is provided with a protective layer 2. The electrode plate 1 is bent to form a corner segment 11, and the corner segment 11 is stacked with several layers. The protective layer 2 is located between the electrode plate 1 and the separator 3 and is disposed on at least a portion of at least one layer of the corner segment 11. The proportion of the number of protective layer 2 layers on the several layers of the corner segment 11 is k. Along the length direction of the electrode plate 1, the distance between the starting end 12 of the electrode plate 1 and the adjacent protective layer 2 is L mm. The electrode plate 1 includes a current collector 13 and an active material layer 14 disposed on at least one side of the current collector 13 along its thickness direction. The thickness of the current collector 13 is d mm, satisfying 1.6 × 10⁻⁶ mm. -3 ≤k / (L×d)≤750×10 -3 .

[0038] By limiting the value of k / (L×d) in the battery of this embodiment, the protective effect of the protective layer 2 on the active material layer 14 is guaranteed, and the loss of active material layer 14 is prevented. At the same time, the lithium ion transport efficiency is improved, the risk of lithium plating is reduced, and the risk of battery short circuit is reduced, thereby improving the battery safety performance.

[0039] It is worth noting that if the value of k / (L×d) is too small, the protective layer 2 will not provide sufficient protection for the active material layer 14, increasing the risk of material loss from the active material layer 14. If the value of k / (L×d) is too large, it will easily cause poor lithium-ion transport, increasing the risk of lithium dendrite formation, which in turn increases the risk of the separator being punctured, leading to a short circuit between the positive and negative electrodes and affecting the safety performance of the battery.

[0040] Optionally, k / (L×d) can be 1.6×10 -3 10×10 -3 20×10 -3 100×10 -3 200×10 -3 300×10 -3400×10 -3 500×10 -3 600×10 -3 700×10 -3 750×10 -3 It can be any value in the range or the value between any two values.

[0041] Research has found that the main reason for material shedding in cell 10 is the high stress at the bending point of current collector 13, which causes the active material to fall off. In this embodiment, by improving the thickness of current collector 13 and controlling the layer ratio of protective layer 2, the risk of material shedding from electrode 1 is reduced. In addition, the lithium-ion transport space near the starting end 12 of electrode 1 is limited, resulting in low lithium-ion transport efficiency. Therefore, by simultaneously limiting the distance between the starting end 12 of electrode 1 and the adjacent protective layer 2, the lithium-ion transport efficiency is improved and the risk of lithium plating is reduced.

[0042] It is worth noting that, please refer to Figure 19 The battery cell 10 includes two bend regions 110 spaced apart from each other and a straight region 120 connecting the two bend regions 110. A corner segment 11 forms the bend region 110. The electrode 1 has m layers stacked at one bend region 110, and the protective layer 2 has n layers at this bend region 110, therefore k = n / m. Specifically, taking... Figure 1 For example, m=6, n=4, therefore k=4 / 6.

[0043] It should be further noted that the electrode can be either a positive or negative electrode. m and n are calculated for an electrode of a specific polarity. In one embodiment, for a single cell, m typically ranges from 20 to 60, and n typically ranges from 1 to 12. For example, if the positive electrode has 60 layers wound in one bending region, and a total of 4 protective layers are applied to the positive electrode in that bending region, then k = 4 / 60.

[0044] Specifically, in one embodiment, such as Figure 3 As shown, active material layers 14 are provided on both opposite sides of the current collector 13 along its thickness direction.

[0045] Of course, in other alternative implementations, such as Figure 4 As shown, the active material layer 14 can also be provided only on one side of the current collector 13 along its thickness direction.

[0046] In one embodiment, the elongation at break of the positive current collector of the positive electrode sheet is less than the elongation at break of the negative current collector of the negative electrode sheet, and at least the positive electrode sheet is provided with a protective layer 2, which is disposed on at least one side surface of the positive electrode sheet along its thickness direction.

[0047] It's worth noting that elongation at break is used to measure a material's ability to undergo plastic deformation. A higher elongation at break indicates better toughness and stronger plastic deformation; a lower elongation at break indicates greater brittleness, making it less prone to deformation and more likely to break. Positive current collectors are typically made of aluminum, which has relatively poor fracture resistance.

[0048] It should be noted that the current collector of the electrode is made of metal foil, and the test method for the elongation at break of the metal foil is in accordance with GB / T29847-2025.

[0049] Of course, in one embodiment, at least one side surface of the negative electrode sheet along its thickness direction is also provided with a protective layer 2.

[0050] In one embodiment, the positive current collector contains aluminum and the negative current collector contains copper.

[0051] Furthermore, in one embodiment, the positive current collector contains Al2O3 and Al3Fe, and the total content of Al2O3 and Al3Fe does not exceed 0.8wt%.

[0052] It is worth noting that an excessively high content of Al2O3 and Al3Fe can lead to an overly brittle positive electrode current collector, making it more prone to breakage and thus increasing the risk of material shedding from the active material layer 14.

[0053] Optionally, the positive electrode current collector contains Al2O3 and Al3Fe, and the total content of Al2O3 and Al3Fe is any one of 0.1wt%, 0.2wt%, 0.3wt%, 0.4wt%, 0.5wt%, 0.6wt%, 0.7wt%, or 0.8wt%, or a value between any two of these values.

[0054] Specifically, in one embodiment, the positive current collector contains iron, with an iron content of 0.1 wt% to 0.5 wt%. This configuration reduces the risk of material loss from the active material layer 14 while ensuring the strength and ductility of the positive current collector.

[0055] It is worth noting that if the iron content is too high, the positive electrode current collector will become too brittle, making it more prone to breakage, which in turn increases the risk of material loss from the active material layer 14. If the iron content is too low, the positive electrode current collector will have poor strength and ductility.

[0056] Optionally, the iron content may be any value from 0.1wt%, 0.15wt%, 0.2wt%, 0.25wt%, 0.3wt%, 0.35wt%, 0.4wt%, 0.45wt%, or 0.5wt%, or a value between any two of these values.

[0057] For example, in the first embodiment, the sum of the mass percentages of Si and Fe is less than or equal to 0.95%, the mass percentage of Cu is less than or equal to 0.20%, the mass percentage of Mn is less than or equal to 0.05%, the mass percentage of Zn is less than or equal to 0.10%, and the mass percentage of Al is greater than or equal to 99.00%. In the second embodiment, the mass percentages of Si are less than or equal to 0.25%, the mass percentage of Fe is less than or equal to 0.40%, the mass percentage of Cu is less than or equal to 0.15%, the mass percentage of Mn is less than or equal to 0.05%, the mass percentage of Mg is less than or equal to 0.05%, the mass percentage of Zn is less than or equal to 0.05%, the mass percentage of V is less than or equal to 0.05%, the mass percentage of Ti is less than or equal to 0.03%, and the mass percentage of Al is greater than or equal to 99.50%. In the third embodiment, the mass percentage of Si is less than or equal to 0.25%, the mass percentage of Fe is less than or equal to 0.35%, the mass percentage of Cu is less than or equal to 0.05%, the mass percentage of Mn is less than or equal to 0.03%, the mass percentage of Zn is less than or equal to 0.05%, the mass percentage of V is less than or equal to 0.05%, the mass percentage of Ti is less than or equal to 0.03%, and the mass percentage of Al is greater than or equal to 99.60%.

[0058] In one embodiment, such as Figure 3 and Figure 4 As shown, the thickness d mm of the current collector 13 satisfies 0.004 mm ≤ d mm ≤ 0.018 mm. This setting reduces the risk of material shedding from the active material layer 14 while ensuring the current-carrying capacity of the electrode 1.

[0059] It is worth noting that if the value of d mm is too large, the current collector 13 will be too thick, which may cause the current collector 13 to break, and thus easily lead to the problem of material loss from the active material layer 14. If the value of d mm is too small, the current collector 13 will be too thin, which may lead to insufficient flow capacity.

[0060] Optionally, d mm can be any value from 0.004 mm, 0.005 mm, 0.006 mm, 0.008 mm, 0.01 mm, 0.012 mm, 0.015 mm, 0.018 mm, or a value between any two of these values.

[0061] Specifically, in one embodiment, for the positive electrode, the thickness d mm of the current collector 13 satisfies 0.006 mm ≤ d mm ≤ 0.018 mm. For the negative electrode, the thickness d mm of the current collector 13 satisfies 0.004 mm ≤ d mm ≤ 0.012 mm.

[0062] In one embodiment, such as Figure 5As shown, the active material layer 14 includes a body region 141 and a thinning region 142, with the thinning region 142 disposed on at least one side of the body region 141 along the width direction of the electrode 1. This arrangement reduces the shedding of active material at the edge of the electrode in the width direction, and at the same time, facilitates the full wetting of the electrolyte into the interior of the electrode, thereby improving the ion transport rate.

[0063] In one embodiment, such as Figure 6 As shown, the current collector 13 includes a main body 131 and a current lead-out portion 132. The current lead-out portion 132 extends from the main body 131 along at least one edge of the electrode 1 in the width direction. Along the length direction of the electrode 1, the distance between the starting end 12 of the main body 131 and the adjacent current lead-out portion 132 is L2 mm, satisfying L2 mm ≤ 300 mm, 1.6 × 10 -3 ≤k / (L×d)≤500×10 -3 .

[0064] It is worth noting that when the value of L2 mm is large, the current carrying capacity of electrode 1 is worse in the area near the starting end 12, the internal resistance is greater, resulting in more severe heat generation, which can easily reduce the adhesion of the protective layer 2, making it easy to fall off or even peel off the active material layer 14. In addition, it will make the battery expansion more severe, and the active material layer 14 is more likely to fall off under greater pressure.

[0065] In one embodiment, such as Figure 6 As shown, along the length of electrode 1, the width of the current lead-out portion 132 is w mm, satisfying 10 mm ≤ w mm ≤ 80 mm. This configuration reduces the risk of material shedding from the active material layer 14 while ensuring the energy density of the battery.

[0066] It is worth noting that if the value of w mm is too small, the current lead-out section 132 will have insufficient overcurrent capacity, leading to more severe heat generation. This can easily reduce the adhesion of the protective layer 2, making it prone to detachment or even peeling off the active material layer 14. If the value of w mm is too large, the current lead-out section 132 will occupy too much space, affecting the energy density of the battery.

[0067] Optionally, w mm can be any value from 10mm, 20mm, 30mm, 40mm, 50mm, 60mm, 70mm, 80mm, or a value between any two of these values.

[0068] In one embodiment, such as Figure 7 and Figure 8 As shown, a protective layer 2 is provided between the starting end 12 of the main body 131 and the adjacent current lead-out portion 132 along the length direction of the electrode 1.

[0069] It is worth noting that the current lead-out portion 132 adjacent to the starting end 12 of the main body portion 131 is the first tab arranged along the length direction of the electrode plate 1 starting from the starting end 12. Therefore, at least one corner segment 11 is provided between the starting end 12 and the first tab along the length direction of the electrode plate 1.

[0070] Furthermore, in one embodiment, such as Figure 8 As shown, the distance L mm between the starting end 12 of the electrode 1 and the adjacent protective layer 2, and the distance L2 mm between the starting end 12 of the main body 131 and the adjacent current lead-out portion 132 satisfy 20 mm ≤ L2 mm - L mm ≤ 200 mm. This setting reduces the risk of material shedding from the active material layer 14 and also reduces the risk of lithium plating in the battery.

[0071] It is worth noting that if the value of L2 mm-L mm is too large, the protective layer 2 may be too close to the starting end 12, resulting in limited lithium-ion transport space in the starting end 12 region of the electrode 1, leading to low lithium-ion transport efficiency and a risk of lithium plating. If the value of L2 mm-L mm is too small, the protective layer 2 may be too close to the current lead-out part 132, causing the protective layer 2 to be significantly affected by the heat generated by the current lead-out part 132, which may reduce the adhesion of the protective layer 2 and make it easy for it to fall off or even peel off the active material layer 14.

[0072] Optionally, L2 mm - L mm can be any value from 20 mm, 40 mm, 60 mm, 80 mm, 100 mm, 120 mm, 140 mm, 160 mm, 180 mm, 200 mm, or a value between any two of these values.

[0073] Specifically, in one embodiment, such as Figure 11 As shown, the width of the current lead-out portion 132 gradually decreases in the direction away from the main body portion 131. The width of the end of the current lead-out portion 132 connected to the main body portion 131 is w1 mm, and the width of the end of the current lead-out portion 132 away from the main body portion 131 is w2 mm, satisfying 8mm≤w1mm-w2mm≤70mm. This arrangement ensures the current carrying capacity of the current lead-out portion 132 while facilitating the convergence and welding of the current lead-out portion 132.

[0074] It is worth noting that if the values ​​of w1 mm and w2 mm are too large, the width of the area of ​​the current lead-out portion 132 away from the main body portion 131 may be too small, making it difficult to close and weld the current lead-out portion 132. If the values ​​of w1 mm and w2 mm are too small, the width of the area of ​​the current lead-out portion 132 close to the main body portion 131 may be too small, which may affect the current carrying capacity of the current lead-out portion 132.

[0075] Optionally, w1 mm-w2 mm can be any value from 8 mm, 10 mm, 20 mm, 30 mm, 40 mm, 50 mm, 60 mm, 70 mm, or any value between two of these values.

[0076] As an alternative implementation, in another embodiment, such as Figure 9 and Figure 10 As shown, along the length of the electrode 1, a current lead-out portion 132 is provided between the starting end 12 of the main body portion 131 and the adjacent protective layer 2. The distance between the current lead-out portion 132 and the protective layer 2 is x mm, satisfying 20 mm ≤ x mm ≤ 200 mm. This arrangement reduces the risk of material loss from the active material layer 14 while facilitating the winding process of the electrode 1.

[0077] It is worth noting that if the value of x mm is too large, the distance between the starting end 12 and the current lead-out portion 132 may be too close, resulting in the electrode 1 having a too small length in the region near the starting end 12, which is not conducive to the winding process of the electrode 1. If the value of x mm is too small, the protective layer 2 may be too close to the current lead-out portion 132, and the protective layer 2 may be greatly affected by the heat generated by the current lead-out portion 132, which may reduce the adhesion of the protective layer 2, making it easy to fall off or even peel off the active material layer 14.

[0078] Optionally, x mm can be any value from 20mm, 40mm, 60mm, 80mm, 100mm, 120mm, 140mm, 160mm, 180mm, 200mm, or a value between any two of these values.

[0079] It is understood that, in alternative embodiments, no corner segment 11 is provided between the starting end 12 and the adjacent current lead-out portion 132.

[0080] In one embodiment, such as Figure 12 As shown, the current collector 13 includes a main body 131 and a current lead-out portion 132. The current lead-out portion 132 extends from the main body 131 along at least one edge of the electrode 1 in the width direction. Along the width direction of the electrode 1, at least one end of the protective layer 2 extends beyond the edge of the main body 131 on the same side by a distance of y mm, satisfying 0.1 mm ≤ y mm ≤ 10 mm. This configuration ensures that the protective layer 2 can completely cover the edge of the active material layer 14, further avoiding the problem of material shedding from the active material layer 14, while also preventing any impact on the energy density of the battery.

[0081] It is worth noting that if the value of y mm is too small, it cannot guarantee effective coverage of the edge of the active material layer 14, and there is still a risk of material falling off. Furthermore, when bonding the protective layer 2 to the electrode 1, the length available for gripping is too small, which is not convenient for the bonding process. If the value of y mm is too large, it is easy to cause additional space occupation in the battery after the cell 10 is installed in the casing, which will affect the energy density of the battery.

[0082] Optionally, y mm can be any value from 0.1mm, 1mm, 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, or a value between any two of these values.

[0083] As an alternative implementation, in another embodiment, such as Figure 13 As shown, the current collector 13 includes a main body 131 and a current lead-out portion 132. The current lead-out portion 132 extends from the main body 131 along at least one edge of the electrode 1 in the width direction. Along the width direction of the electrode 1, at least one end of the protective layer 2 does not extend beyond the edge of the main body 131 on the same side, and the distance between the end of the protective layer 2 and the edge of the main body 131 is z mm, satisfying 1 mm ≤ z mm ≤ 15 mm. This configuration reduces the risk of material shedding from the active material layer 14 while also reducing the risk of lithium plating in the battery.

[0084] It is worth noting that if the value of z mm is too large, the coverage area of ​​the protective layer 2 over the corner segment 11 may be too small, posing a risk of material loss in the uncovered areas of the corner segment 11. If the value of z mm is too large, the coverage area of ​​the corner segment 11 will be too large, affecting the lithium-ion transport efficiency and exacerbating the lithium plating problem in the battery.

[0085] Optionally, z mm can be any value from 1mm, 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 11mm, 12mm, 13mm, 14mm, 15mm, or a value between any two of these values.

[0086] Furthermore, in the above alternative implementations, such as Figure 14 As shown, along the width direction of the electrode 1, the edge of the separator 3 extends beyond the edge of the main body 131 on the same side, while the end of the protective layer 2 does not extend beyond the edge of the separator 3 on the same side. This arrangement ensures that the protective layer 2 can completely cover the edge of the active material layer 14, further preventing the problem of material shedding from the active material layer 14, improving the adhesion strength of the protective layer 2, and also avoiding any impact on the energy density of the battery.

[0087] Alternatively, in another alternative implementation, such as Figure 15As shown, along the width direction of the electrode 1, the edge of the separator 3 extends beyond the edge of the main body 131 on the same side, and the end of the protective layer 2 extends beyond the edge of the separator 3 on the same side, with an extension distance of u mm, satisfying u mm ≤ 9.4 mm. This arrangement can reduce the impact on the energy density of the battery.

[0088] Optionally, u mm can be any value from 0.1mm, 1mm, 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 9.4mm, or a value between any two of these values.

[0089] In one embodiment, such as Figure 2 As shown, along the length of electrode 1, the width of protective layer 2 is a mm, satisfying 10 mm ≤ a mm ≤ 30 mm. This configuration avoids material shedding from active material layer 14 while reducing the risk of lithium plating in the battery.

[0090] It is worth noting that if the value of a mm is too small, the coverage area of ​​corner segment 11 will be too small, and there is a risk of material loss in the uncovered areas of corner segment 11. If the value of a mm is too large, the coverage area of ​​corner segment 11 will be too large, affecting the lithium-ion transport efficiency and exacerbating the lithium plating problem in the battery.

[0091] Optionally, the value of a mm can be any one of 10 mm, 12 mm, 15 mm, 18 mm, 20 mm, 22 mm, 25 mm, 28 mm, or 30 mm, or a value between any two of these values.

[0092] In one embodiment, the proportion k of the number of protective layer 2 layers at several corner segments 11 satisfies 0.017 ≤ k ≤ 0.3. This configuration reduces the risk of material shedding from the active material layer 14 while also reducing the risk of lithium plating in the battery.

[0093] It is worth noting that if the value of k is too large, the coverage area of ​​electrode 1 will be too large, the lithium-ion transport path will be lengthened, resulting in poor lithium-ion transport and easily causing lithium plating problems. If the value of k is too small, it may result in insufficient protection for the active material layer 14, leading to the risk of material shedding.

[0094] Optionally, k can take any value from 0.017, 0.05, 0.08, 0.1, 0.15, 0.2, 0.25, 0.28, 0.3, or a value between any two values.

[0095] Specifically, in one embodiment, among the stacked corner segments 11, the protective layer 2 is disposed within the corner segment 11 within the six layers closest to the starting end 12 of the electrode 1. The electrode 1 experiences greater stress within the five rings closest to the starting end 12, making it more prone to material loss. Therefore, the protective layer 2 is disposed within the five rings closest to the starting end 12 of the electrode 1 to reduce the risk of material loss while ensuring the volumetric energy density of the battery.

[0096] In one embodiment, such as Figure 20 and Figure 22 As shown, the electrode 1 is wound into several turns. A crease 111 is formed at the corner 11 of the first turn near the starting end 12 of the electrode 1. The protective layer 2 covers the crease 111. The stress is most concentrated in the first turn of the cell 10, which will form the crease 111 and has a greater risk of material falling out. Covering the crease 111 with the protective layer 2 can reduce the risk of material falling out at the crease 111.

[0097] Furthermore, in one embodiment, such as Figure 22 As shown, along the length of electrode 1, the edge of the protective layer 2 extends beyond the crease 111 by a distance of r mm, satisfying r mm ≥ 3 mm. It is worth noting that if the value of r is too small, material may easily fall off at the crease 111; in addition, if the value of r is too large, it may easily cause lithium plating problems. Therefore, the value of r does not need to be too large.

[0098] Specifically, in one embodiment, such as Figure 1 As shown, protective layers 2 are provided on both opposite sides of the electrode 1 along its thickness direction. This arrangement further prevents the active material layer 14 from shedding.

[0099] In one embodiment, such as Figure 16 As shown, along the length of electrode 1, electrode 1 also includes a horizontal section 15 connected to corner section 11. The protective layer 2 extends to the horizontal section 15, and the extension distance is L3 mm, satisfying L3 mm ≤ 15 mm. This arrangement ensures the adhesion stability of the protective layer 2 on electrode 1 and the protection effect on corner section 11, while reducing the risk of lithium plating in the battery.

[0100] It is worth noting that if the value of L3 mm is too large, the coverage area of ​​electrode 1 will be too large, affecting the lithium-ion transport efficiency and exacerbating the lithium plating problem in the battery.

[0101] Optionally, L3 mm can be any value from 1mm, 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 11mm, 12mm, 13mm, 14mm, 15mm, or a value between any two of these values.

[0102] Understandably, horizontal segment 15 is used to form straight section 120.

[0103] In one embodiment, such as Figure 17 and Figure 18 As shown, the protective layer 2 includes a base layer 21 and an adhesive layer 22. The adhesive layer 22 is bonded to the electrode 1, and the base layer 21 is disposed on the side of the adhesive layer 22 away from the electrode 1. That is, the base layer 21 is bonded to the electrode 1 using the adhesive layer 22.

[0104] Specifically, the material of base layer 21 can be: polyvinyl chloride, polyethylene, polypropylene, polyvinylidene fluoride, or hexafluoropropylene. Vinylidene fluoride copolymer, tetrafluoropropylene Vinylidene fluoride copolymer, trifluorochloropropylene At least one of the following: vinylidene fluoride copolymer, polyethylene terephthalate, polyimide, polyetherimide, polycarbonate, polystyrene, polyphenylene sulfide, polyvinylidene fluoride, polyvinylidene fluoride copolymer, polyarylate, fiber, nylon, nonwoven fabric, etc.

[0105] Specifically, the material of the adhesive layer 22 can be at least one of the following: acrylic-acrylate copolymer, butadiene-styrene copolymer, styrene-acrylic copolymer, styrene-acrylate copolymer, ethylene-vinyl acetate copolymer, acrylic-grafted polyethylene, maleic anhydride-grafted polyethylene, acrylic-grafted polypropylene, polyvinylidene fluoride, maleic anhydride-grafted polypropylene, carboxymethyl cellulose, polyimide, polyetherimide, styrene-isoprene-styrene copolymer rubber, polyethylene phthalate, ethylene-vinyl acetate copolymer bisphenol A type epoxy resin, ethylene-vinyl acetate copolymer bisphenol F type epoxy resin, glycerol ether type epoxy resin, glycerol ester type epoxy resin, silicone type resin, polyurethane, styrene-isoprene-styrene copolymer, etc.

[0106] Furthermore, in one embodiment, such as Figure 17 and Figure 18 As shown, the base layer 21 has through holes 211 extending along its thickness direction, and the pore density of the through holes 211 ranges from 1% to 30%. This arrangement ensures the adhesion between the protective layer 2 and the corner segment 11, while also ensuring the wetting effect of the electrolyte and the lithium ion transport efficiency.

[0107] It is worth noting that by opening through holes 211 on the base layer 21, wetting channels for electrolyte are provided, making the electrolyte wetting more sufficient and serving as a lithium ion transport channel. This significantly reduces lithium plating problems inside the battery, reduces the formation of lithium dendrites, and lowers the risk of short circuits caused by puncturing the separator 3.

[0108] It should be further noted that if the pore density is too small, the channels for electrolyte and lithium ion transport will be too small, affecting the wetting effect of the electrolyte and the transport efficiency of lithium ions, increasing the risk of lithium dendrite formation, and increasing the risk of short circuit between the positive and negative electrodes due to puncture of the separator 3, thus affecting the safety performance of the battery. If the pore density is too large, it may affect the reliability of the adhesive layer 22 adhering to the corner section 11, which may easily lead to the detachment of the protective layer 2, or even the peeling off of the active material layer 14.

[0109] Optionally, the pore density of the through hole 211 can be any value among 1%, 5%, 10%, 15%, 20%, 25%, and 30%, or a value between any two of these values.

[0110] In this embodiment, the pore density measurement method is as follows:

[0111] Remove the protective layer from the battery sample and dry it at 60°C for 60 minutes. After ensuring the sample is dry, measure the length and width of the protective layer sample with a micrometer and calculate the sample area.

[0112] The pore structure of the through-holes in the protective layer sample was observed using a scanning electron microscope (SEM), and the total area of ​​the through-holes on the protective layer sample was measured.

[0113] Pore ​​density calculation formula: Pore density = (Total area of ​​through holes / Sample area) × 100%.

[0114] Furthermore, in one embodiment, such as Figure 17 and Figure 18 As shown, the adhesive layer 22 has a blank area 221. Along the length direction of the electrode 1, the width of the blank area 221 is b mm, which satisfies 1 mm ≤ b mm ≤ 10 mm.

[0115] It is worth noting that if the value of b mm is too large, the area where the adhesive zone 222 is set will be too small, affecting the reliability of the bonding between the protective layer 2 and the corner section 11. This can easily lead to the protective layer 2 falling off, or even peeling off the active material layer 14. If the value of b mm is too small, the area available for setting the through hole 211 will be too small. The base layer 21 will have too much obstruction effect on the electrolyte and lithium ions, affecting the wetting effect of the electrolyte and the transport efficiency of lithium ions. This increases the risk of lithium dendrite formation, which increases the risk of the separator being punctured and causing a short circuit between the positive and negative electrodes, thus affecting the safety performance of the battery.

[0116] Optionally, b mm can be any value from 1mm, 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, or a value between any two of these values.

[0117] Specifically, in one alternative implementation, such as Figure 17 As shown, along the length of the electrode 1, blank areas 221 are provided on opposite sides of the base layer 21; that is, along the length of the electrode 1, the middle area of ​​the base layer 21 is the adhesive area 222, and the opposite sides of the adhesive area 222 are blank areas 221. In this case, the width of the blank area 221 on one side is b1 mm, and the width of the blank area 221 on the other side is b2 mm. Therefore, b mm = b1 mm + b2 mm. In another optional embodiment, as... Figure 18 As shown, along the width direction of the electrode 1, the blank area 221 is set on the opposite sides of the base layer 21; that is, along the width direction of the electrode 1, the middle area of ​​the base layer 21 is the adhesive area 222, and the opposite sides of the adhesive area 222 are blank areas 221.

[0118] Specifically, in one embodiment, such as Figure 17 and Figure 18 As shown, through holes 211 are provided in the area corresponding to the base layer 21 and the blank area 221.

[0119] In one embodiment, such as Figure 2 As shown, the distance L mm between the starting end 12 of the electrode 1 and the adjacent protective layer 2 satisfies 80 mm ≤ L mm ≤ 700 mm. This setting ensures the transmission efficiency of the electrode 1 in the region of the starting end 12 while reducing the risk of material shedding from the active material layer 14.

[0120] It is worth noting that if the value of L mm is too large, there is a risk that the corner section 11 located in the inner ring after the electrode 1 is wound may not be completely covered, increasing the risk of material loss from the active material layer 14. If the value of L mm is too small, the lithium-ion transport space in the starting end 12 region of the electrode 1 is limited, the lithium-ion transport efficiency is low, and there is a risk of lithium plating.

[0121] Optionally, L mm can be any value among 80mm, 100mm, 200mm, 300mm, 400mm, 500mm, 600mm, and 700mm, or a value between any two of these values.

[0122] In one embodiment, such as Figure 19 As shown, in the extension direction perpendicular to the straight region 120, the thickness of the battery cell 10 is t mm. When t mm ≥ 40 mm, it satisfies 20 × 10⁻⁶ mm. -3 ≤k / (L×d)≤700×10 -3 .

[0123] It is worth noting that the greater the thickness of the cell 10, the more likely it is to cause excessive stress concentration at the inner bend of the electrode 1, increasing the risk of material loss from the inner ring and slowing down the ion transport rate, thus increasing the risk of lithium plating. Therefore, by further limiting the value of k / (L×d), both the risk of material loss and the risk of lithium plating can be reduced.

[0124] According to an embodiment of the present invention, in another aspect, a battery device is also provided, comprising: the battery described above.

[0125] Battery devices can serve as operating power sources or driving power sources for electrical devices, replacing or partially replacing fuel or natural gas to provide driving power for vehicles. Electrical devices encompass a wide range of technological fields, including energy storage devices, electric ships, aircraft, laptops, power tools, electric bicycles, electric motorcycles, electric cars, military equipment, and aerospace.

[0126] The battery device includes multiple battery packs, which can be connected in series, parallel, or a combination thereof. A combination thereof means that multiple battery packs are connected in both series and parallel.

[0127] The battery device is a cluster-level battery structure formed by multiple battery packs connected in series, wherein the number of battery packs in each cluster is strictly configured according to voltage and capacity requirements. Specifically, the battery unit of the battery device includes multiple batteries, some of which are connected in series to form a cluster that meets the preset power supply voltage requirements, and at least one spare battery among the multiple batteries is bypassed.

[0128] The battery device may include: battery cells and a switching control unit.

[0129] The present application will be further described in detail below with reference to specific embodiments, which should not be construed as limiting the scope of protection claimed in the present application.

[0130] The preparation of the example battery and the comparative battery includes the following steps:

[0131] (1) Preparation of the positive electrode:

[0132] The prepared positive electrode active material, conductive agent acetylene black, and binder PVDF are mixed, and solvent NMP is added. The mixture is stirred under vacuum until the system is homogeneous to obtain a positive electrode slurry. The positive electrode slurry is uniformly coated on both surfaces of the positive electrode current collector aluminum foil, air-dried at room temperature, and then transferred to an oven for further drying. Finally, it is cold-pressed and slit to obtain the positive electrode sheet. Specifically, the mass ratio of positive electrode active material: conductive agent: binder satisfies (92~98):(4~1):(4~1).

[0133] (2) Preparation of negative electrode:

[0134] The negative electrode active material, conductive agent acetylene black, thickener CMC, and binder SBR are mixed, and deionized water is added as a solvent. The mixture is stirred under vacuum until the system is homogeneous to obtain a negative electrode slurry. The negative electrode slurry is uniformly coated on both surfaces of the negative electrode current collector copper foil, air-dried at room temperature, and then transferred to an oven for further drying. After cold pressing and slitting, the negative electrode sheet is obtained. The ratio of negative electrode active material: conductive agent: thickener: binder satisfies (90~96): (4~2): (2~1): (4~1).

[0135] (3) Preparation of electrolyte:

[0136] Ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) were mixed in a volume ratio of 1:1:1 to obtain an organic solvent. Then, fully dried lithium salt LiPF6 was dissolved in the mixed organic solvent to prepare an electrolyte with a concentration of 1 mol / L.

[0137] (4) Preparation of the diaphragm:

[0138] Polyethylene film is selected as the diaphragm.

[0139] (5) Preparation of lithium-ion batteries:

[0140] The positive electrode, separator, and negative electrode are stacked in sequence and wound to form a bare battery cell, with a protective layer attached to the corner sections of the electrode. The bare cell is then placed in a battery casing, which is a square casing. The battery is dried, injected with electrolyte, and then packaged, allowed to stand, formed, and volume-adjusted to obtain a lithium-ion battery.

[0141] The positive electrode active material can be selected from one or more lithium-containing positive electrode active materials, including lithium iron phosphate, ternary materials containing nickel, cobalt, and manganese, and lithium manganese iron phosphate; the negative electrode active material can be selected from one or more negative electrode active main materials, such as artificial graphite, natural graphite, silicon carbide, silicon oxide, and lithium titanate.

[0142] The relevant performance of the batteries in the above embodiments and comparative examples was tested, and the test results are recorded in Table 1. The test methods are as follows:

[0143] Performance 1: Battery capacity retention rate

[0144] Following the battery preparation method described above, corresponding lithium-ion batteries were prepared for each embodiment and comparative example. The parameters of the protective layer and cell in the lithium-ion batteries obtained in each embodiment and comparative example are shown in Table 1. All other structures are identical. The lithium-ion battery was charged at room temperature (25°C) with a constant current of 0.33C to the upper limit voltage, and then charged with a constant voltage of 0.33C until the current dropped to 0.05C. After standing for 5 minutes, the battery was discharged with a constant current of 0.33C to the lower limit voltage. This process was repeated three times to obtain the third discharge capacity Q1, which was taken as the fixed capacity.

[0145] The lithium-ion battery is charged at room temperature (25℃) with a constant current of 0.33C to the upper limit voltage, then charged with a constant voltage of 0.33C until the current drops to 0.05C. After resting for 5 minutes, the battery is discharged with a constant current of 0.33C to the lower limit voltage. This constitutes one cycle. After n cycles, the discharge capacity Qn of the battery on the nth cycle is recorded. The battery capacity retention rate is calculated using the formula "Battery capacity retention rate = Qn / Q1 × 100%". The number of cycles n when the capacity retention rate first falls below 80% is recorded as the number of cycles for that battery. If n is less than 1200, the battery is considered unqualified; if n is greater than or equal to 1200 and less than 1400, the battery is considered qualified; and if n is greater than or equal to 1400, the battery is considered good.

[0146] When the positive electrode active material of the battery is a nickel-cobalt-manganese ternary cathode, the upper limit voltage is 4.25V and the lower limit voltage is 2.5V. When the positive electrode active material of the battery is lithium iron phosphate, the upper limit voltage is 3.6V and the lower limit voltage is 2.5V.

[0147] In this test, the active material for the positive electrode of the battery was selected from a nickel-cobalt-manganese ternary LiNi alloy. 0.6 Co 0.2 Mn 0.2 Taking O2 as an example, the mass ratio of positive electrode active material: conductive agent: binder meets 96:2:2; the negative electrode active material is selected from artificial graphite, and the ratio of negative electrode active material: conductive agent: thickener: binder meets 95:2:1:2.

[0148] Performance 2: Battery Lithium Plating

[0149] Following the battery preparation method described above, corresponding lithium-ion batteries were prepared for each embodiment and comparative example. The parameters of the protective layer and cell in the lithium-ion batteries obtained in each embodiment and comparative example are shown in Table 1. All other structures are identical. The lithium-ion battery was charged at room temperature (25°C) with a constant current of 0.33C to the upper limit voltage, then charged at a constant voltage until the current dropped to 0.05C. After standing for 5 minutes, the battery was discharged with a constant current of 0.33C to the lower limit voltage. This constituted one cycle, and 2000 cycles were performed. Then, the lithium-ion battery was charged at 0.33C to the upper limit voltage, with a cutoff current less than or equal to 0.05C, resulting in a fully charged battery.

[0150] Disassemble the battery, then remove the electrodes and observe the lithium plating on the surface of the negative electrode in the corner section. The part where the projection of a single protective layer coincides with the electrode is the first region, and the lithium plating area of ​​the first region is measured and recorded as S1. The area of ​​the corner section of the protective layer in the first region is S2. According to the formula, the percentage of the lithium plating area on the surface of the negative electrode corner section = (S1 / S2) × 100%, the percentage of the lithium plating area on the surface of the negative electrode corner section is calculated. If the lithium plating area on the surface of the negative electrode corner section is less than 10%, it is considered slight lithium plating; if the lithium plating area on the surface of the negative electrode corner section is between 10% and 50%, it is considered moderate lithium plating; and if the lithium plating area on the surface of the negative electrode corner section is greater than 50%, it is considered severe lithium plating. Batteries with severe lithium plating are unqualified products.

[0151] When the positive electrode active material of the battery is a nickel-cobalt-manganese ternary cathode, the upper limit voltage is 4.25V and the lower limit voltage is 2.5V. When the positive electrode active material of the battery is lithium iron phosphate, the upper limit voltage is 3.6V and the lower limit voltage is 2.5V.

[0152] In this test, the positive electrode active material of the battery was selected from a nickel-cobalt-manganese ternary LiNi alloy. 0.6 Co 0.2 Mn 0.2 Taking O2 as an example, the mass ratio of positive electrode active material: conductive agent: binder satisfies 96:2:2; the negative electrode active material is selected from artificial graphite, and the ratio of negative electrode active material: conductive agent: thickener: binder satisfies 95:2:1:2.

[0153] Table 1:

[0154]

[0155] As can be seen from Table 1, in Examples 1 to 16, the value of k / (L×d) is all within 1.6×10. -3 Up to 750×10 -3 Within the specified range, therefore, the batteries of Examples 1 to 16 do not have any unqualified capacity retention rate, and the batteries do not have serious lithium plating problems.

[0156] As can be seen from Table 1, in Comparative Example 1 and Comparative Example 3, the value of k / (L×d) is not greater than 1.6×10. -3 Up to 750×10 -3 Within the range and greater than 750×10 -3 This resulted in severe lithium plating problems in the batteries of Comparative Example 1 and Comparative Example 3.

[0157] As can be seen from Table 1, in Comparative Example 2, the value of k / (L×d) is not greater than 1.6×10. -3 Up to 750×10 -3 Within the range and less than 1.6 × 10 -3This resulted in the battery capacity retention rate of Comparison 2 failing to meet the standard.

[0158] The following defines and explains some of the terms used in this application.

[0159] The positive electrode is one of the core components in a battery that carries the positive electrode active material. During charging, metal ions (such as lithium ions) are released from the crystal lattice of the positive electrode active material (oxidation reaction), migrate through the electrolyte, and intercalate into the negative electrode. During discharging, metal ions (such as lithium ions in a lithium battery) are released from the negative electrode and intercalate into the crystal lattice of the positive electrode active material (reduction reaction), thus realizing the storage and release of lithium ions.

[0160] A positive electrode generally includes a positive current collector (current collector layer) and a positive active material layer. The positive active material layer is coated on at least one surface of the positive current collector and includes: positive active material, conductive agent and binder.

[0161] The positive electrode active material is the donor of metal ions, such as lithium ions and sodium ions, provided by the battery cell. For example, in the positive electrode of a lithium-ion battery, the positive electrode active material can reversibly intercalate and deintercalate lithium ions, serving as the core carrier for the battery's storage and release of chemical energy. Positive electrode active materials include, but are not limited to, at least one of the following: lithium-containing phosphates, lithium transition metal oxides and their respective modified compounds, or other conventional materials that can be used as positive electrode active materials for batteries. These positive electrode active materials can be used alone or in combination of two or more. Among them, lithium-containing phosphates include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also abbreviated as LFP)), lithium iron phosphate and carbon composites, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate and carbon composites, lithium iron manganese phosphate, and lithium iron manganese phosphate and carbon composites. Lithium transition metal oxides include, but are not limited to, lithium cobalt oxides (such as LiCoO2), lithium nickel oxides (such as LiNiO2), lithium manganese oxides (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxides, lithium manganese cobalt oxides, lithium nickel manganese oxides, and lithium nickel cobalt manganese oxides (such as LiNi). 1 / 3Co 1 / 3 Mn 1 / 3 O2 (also known as NCM333), LiNi 0.5 Co 0.2 Mn 0.3 O2 (also known as NCM523), LiNi 0.5 Co 0.25 Mn 0.25 O2 (also known as NCM211), LiNi 0.6 Co 0.2 Mn 0.2 O2 (also known as NCM622), LiNi0.8 Co 0.1 Mn 0.1 O2 (also known as NCM811), lithium nickel cobalt aluminum oxide (such as LiNi) 0.85 Co 0.15 Al 0.05 At least one of O2 and its modified compounds.

[0162] The positive electrode conductive agent includes, but is not limited to, one or more combinations of graphite, superconducting carbon, carbon black (such as acetylene black, Ketjen black, SuperP, etc.), carbon nanotubes, graphene and carbon nanofibers.

[0163] The positive electrode binder includes, but is not limited to, one or more combinations of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, fluorinated acrylate resin, styrene-butadiene rubber, polyacrylic acid, sodium polyacrylate, polyacrylamide, polyvinyl alcohol, sodium alginate, polymethacrylic acid, carboxymethyl chitosan, etc.

[0164] During battery charging, active ions (such as Li) from the positive electrode are embedded in the negative electrode, while electrons from the positive electrode are transferred to the negative electrode through an external circuit to maintain charge balance. During discharge, the active ions (such as Li) previously embedded in the negative electrode can be released, while electrons from the negative electrode are transferred to the positive electrode through an external circuit to maintain charge balance, thus achieving energy storage and release.

[0165] The negative electrode sheet includes a negative current collector (current collector layer) and a negative active layer disposed on at least one surface of the negative current collector. The negative current collector is a conductive metal foil, which can be made of stainless steel, copper, aluminum, nickel, carbon electrodes, or titanium with a silver-plated surface. Composite current collectors may include a polymer base material and a metal layer. Composite current collectors can be formed by forming a metal material (aluminum, aluminum alloy, copper, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer base material (such as polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.). The negative active layer includes a negative active material, a conductive agent, and a binder.

[0166] The negative electrode active material can be carbon-based materials such as graphite, porous carbon, hard carbon, soft carbon, and mesophase carbon microspheres, or silicon-based materials such as elemental silicon, silicon oxides, silicon-carbon composites, and silicon-nitrogen composites, or tin-based materials (elemental tin, tin oxides, and tin alloys, etc.), or lithium titanate materials, or metallic lithium materials, etc. The conductive agent can be conductive carbon black, carbon nanotubes, etc., and the binder can be styrene-butadiene rubber, polyacrylic acid, etc.

[0167] The positive current collector serves as a substrate and is mainly used to attach the positive active material, thereby collecting the current generated by the positive active material and outputting the current to the outside.

[0168] The positive electrode current collector can be a metal foil or a composite current collector. For example, as a metal foil, it can be made of stainless steel, copper, aluminum, nickel, carbon electrodes, or titanium with a silver-plated surface. The composite current collector may include a polymer material base layer and a metal layer. The composite current collector can be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0169] The negative electrode current collector serves to collect current and acts as a carrier for the negative electrode slurry. The negative electrode slurry (negative electrode active material, conductive agent, binder, etc.) is coated onto the negative electrode current collector. The negative electrode current collector collects electrons from the negative electrode active material and conducts them to the external circuit, realizing the process of converting chemical energy into electrical energy.

[0170] The negative electrode current collector can be made of stainless steel, copper, aluminum, nickel, carbon electrodes, or titanium, and can be surface-plated with silver. Composite current collectors may include a polymer substrate and a metal layer. Composite current collectors can be formed by forming a metal material (aluminum, aluminum alloy, copper, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer substrate (such as polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0171] The tab is located on one side of the positive / negative current collector and is separately or integrally formed with the current collector. It is electrically connected to the current collector to conduct the current on the corresponding current collector. The tab is made of a composite material formed by a base layer of a highly conductive metal material (such as copper, aluminum, copper or nickel) and a metal layer.

[0172] A diaphragm (separator) is placed between the positive and negative electrodes to separate them and prevent them from short-circuiting due to contact.

[0173] The diaphragm can be at least one of glass fiber, nonwoven fabric, polyethylene (PE), polypropylene (PP), and polyvinylidene fluoride. A coating can also be applied to the diaphragm surface. The coating can be an inorganic coating and / or an organic coating, wherein the inorganic coating material includes at least one of alumina, silicon oxide, titanium oxide, magnesium oxide, zirconium oxide, and boehmite; and the organic coating includes at least one of aramid coating and polyvinylidene fluoride (PVDF) coating.

[0174] A wound cell (wound core) generally refers to a cell made by winding continuous positive electrode plates, negative electrode plates, and separators. The separator is located between adjacent positive and negative electrode plates.

[0175] Although embodiments of the 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 invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A battery, characterized in that, include: Housing assembly; A battery cell (10) is disposed within the housing assembly. The battery cell (10) is formed by winding a positive electrode, a separator (3), and a negative electrode that are stacked together. At least one electrode (1) of the positive electrode and the negative electrode is provided with a protective layer (2). The electrode (1) is bent to form a corner segment (11). The corner segment (11) is stacked in several layers. The protective layer (2) is located between the electrode (1) and the separator (3) and is disposed on at least one of the layers. At least a portion of the corner segment (11); in a plurality of stacked corner segments (11), the protective layer (2) is disposed within six layers of the corner segment (11) near the starting end (12) of the electrode (1); the proportion of the number of layers of the protective layer (2) on the plurality of corner segments (11) is k; along the length direction of the electrode (1), the distance between the starting end (12) of the electrode (1) and the adjacent protective layer (2) is L mm; the electrode (1) includes a current collector (13) and an active material layer (14) disposed on at least one side of the current collector (13) along its thickness direction; the thickness of the current collector (13) is d mm, satisfying 1.6 × 10⁻⁶ mm. -3 ≤k / (L×d)≤750×10 -3 , 0.004mm≤d mm≤0.018mm, 0.017≤k≤0.3, 80mm≤L mm≤700mm.

2. The battery according to claim 1, characterized in that, The elongation at break of the positive current collector of the positive electrode sheet is less than the elongation at break of the negative current collector of the negative electrode sheet. At least the positive electrode sheet is provided with the protective layer (2), which is disposed on at least one side surface of the positive electrode sheet along its thickness direction.

3. The battery according to claim 2, characterized in that, The protective layer (2) is also provided on at least one side surface of the negative electrode along its thickness direction.

4. The battery according to claim 2, characterized in that, The positive current collector contains aluminum, and the negative current collector contains copper.

5. The battery according to claim 4, characterized in that, The positive electrode current collector contains Al2O3 and Al3Fe, and the total content of Al2O3 and Al3Fe does not exceed 0.8wt%.

6. The battery according to claim 4, characterized in that, The positive current collector contains iron, and the iron content is from 0.1 wt% to 0.5 wt%.

7. The battery according to claim 1, characterized in that, The active material layer (14) includes a body region (141) and a thinning region (142), wherein the thinning region (142) is disposed on at least one side of the body region (141) along the width direction of the electrode (1).

8. The battery according to claim 1, characterized in that, The current collector (13) includes a main body (131) and a current lead-out portion (132). The current lead-out portion (132) extends from the main body (131) along at least one edge of the electrode (1) in the width direction. Along the length direction of the electrode (1), the distance between the starting end (12) of the main body (131) and the adjacent current lead-out portion (132) is L2 mm, satisfying L2 mm ≤ 300 mm, 1.6 × 10 -3 ≤k / (L×d)≤500×10 -3 .

9. The battery according to claim 8, characterized in that, Along the length direction of the electrode (1), the width of the current lead-out portion (132) is w mm, which satisfies 10 mm ≤ w mm ≤ 80 mm.

10. The battery according to claim 8, characterized in that, Along the length direction of the electrode (1), a protective layer (2) is provided between the starting end (12) of the main body (131) and the adjacent current lead-out portion (132).

11. The battery according to claim 10, characterized in that, The distance L mm between the starting end (12) of the electrode (1) and the adjacent protective layer (2) and the distance L2 mm between the starting end (12) of the main body (131) and the adjacent current lead-out part (132) satisfy 20 mm ≤ L2 mm - L mm ≤ 200 mm.

12. The battery according to claim 9, characterized in that, The width of the current lead-out portion (132) gradually decreases in the direction of moving away from the main body portion (131). The width of the end of the current lead-out portion (132) connected to the main body portion (131) is w1 mm, and the width of the end of the current lead-out portion (132) away from the main body portion (131) is w2 mm, satisfying 8 mm ≤ w1 mm - w2 mm ≤ 70 mm.

13. The battery according to claim 8, characterized in that, Along the length direction of the electrode (1), a current lead-out portion (132) is provided between the starting end (12) of the main body portion (131) and the adjacent protective layer (2), and the distance between the current lead-out portion (132) and the protective layer (2) is x mm, satisfying 20 mm ≤ x mm ≤ 200 mm.

14. The battery according to any one of claims 1 to 13, characterized in that, The current collector (13) includes a main body (131) and a current lead-out portion (132). The current lead-out portion (132) extends from the main body (131) along at least one edge of the electrode (1) in the width direction. Along the width direction of the electrode (1), at least one end of the protective layer (2) extends beyond the edge of the main body (131) on the same side by a distance of y mm, satisfying 0.1 mm ≤ y mm ≤ 10 mm.

15. The battery according to any one of claims 1 to 13, characterized in that, The current collector (13) includes a main body (131) and a current lead-out portion (132). The current lead-out portion (132) extends from the main body (131) along at least one edge of the electrode (1) in the width direction. Along the width direction of the electrode (1), at least one end of the protective layer (2) does not extend beyond the edge of the main body (131) on the same side. The distance between the end of the protective layer (2) and the edge of the main body (131) is z mm, which satisfies 1 mm ≤ z mm ≤ 15 mm.

16. The battery according to claim 14, characterized in that, Along the width direction of the electrode (1), the edge of the diaphragm (3) extends beyond the edge of the main body (131) on the same side, and the end of the protective layer (2) does not extend beyond the edge of the diaphragm (3) on the same side.

17. The battery according to claim 14, characterized in that, Along the width direction of the electrode (1), the edge of the diaphragm (3) extends beyond the edge of the main body (131) on the same side, and the end of the protective layer (2) extends beyond the edge of the diaphragm (3) on the same side, with an extension distance of u mm, satisfying u mm ≤ 9.4 mm.

18. The battery according to any one of claims 1 to 13, characterized in that, Along the length direction of the electrode (1), the width of the protective layer (2) is a mm, satisfying 10 mm ≤ a mm ≤ 30 mm.

19. The battery according to any one of claims 1 to 13, characterized in that, The electrode (1) is wound in several turns, and a crease (111) is formed at the corner segment (11) of the first turn near the starting end (12) of the electrode (1), and the protective layer (2) covers the crease (111).

20. The battery according to claim 19, characterized in that, Along the length direction of the electrode (1), the edge of the protective layer (2) extends beyond the crease (111) by a distance of r mm, satisfying r mm ≥ 3 mm.

21. The battery according to any one of claims 1 to 13, characterized in that, The electrode (1) has a protective layer (2) on both opposite sides along its thickness direction.

22. The battery according to any one of claims 1 to 13, characterized in that, Along the length direction of the electrode (1), the electrode (1) also includes a horizontal section (15) connected to the corner section (11), and the protective layer (2) extends to the horizontal section (15) with an extension distance of L3 mm, satisfying L3 mm≤15 mm.

23. The battery according to any one of claims 1 to 13, characterized in that, The protective layer (2) includes a base layer (21) and an adhesive layer (22), the adhesive layer (22) being bonded to the electrode (1), and the base layer (21) being disposed on the side of the adhesive layer (22) away from the electrode (1).

24. The battery according to claim 23, characterized in that, The base layer (21) has through holes (211) that extend through its thickness direction, and the pore density of the through holes (211) ranges from 1% to 30%.

25. The battery according to claim 23, characterized in that, The adhesive layer (22) has a blank area (221) along the length direction of the electrode (1), and the width of the blank area (221) is b mm, satisfying 1 mm ≤ b mm ≤ 10 mm.

26. The battery according to claim 25, characterized in that, The base layer (21) has through holes (211) that extend through it along its thickness direction. The through holes (211) are located in the area of ​​the base layer (21) corresponding to the blank area (221).

27. The battery according to any one of claims 1 to 13, characterized in that, Along the length direction of the electrode (1), the electrode (1) further includes a horizontal section (15) connected to the corner section (11). The battery cell (10) includes two bend areas (110) arranged at intervals and a straight area (120) connected between the two bend areas (110). The corner section (11) is used to form the bend area (110), and the horizontal section (15) is used to form the straight area (120). In the extension direction perpendicular to the straight area (120), the thickness of the battery cell (10) is t mm. When t mm ≥ 40 mm, it satisfies 20 × 10 -3 ≤k / (L×d)≤700×10 -3 .

28. A battery device, characterized in that, include: The battery according to any one of claims 1 to 27.

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