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 winding core formed by winding positive electrode sheets, diaphragms and negative electrode sheets arranged in a laminated mode, at least one of the positive electrode sheets and the negative electrode sheets is provided with an elastic coating, the electrode sheet is formed with a bending section arranged in a bending mode, the electrode sheet comprises a current collector and an active material layer arranged on at least one surface of the current collector, and the elastic coating is at least partially coated on the surface of the active material layer at the bending section; wherein the area density of the elastic coating is A, the thickness of the elastic coating is d, the Vickers hardness of the current collector is k, and the particle size of active particles in the active material layer is D v50 , and the following condition is met: 0.01 <= k / (AxdxD v50 ) <= 30.07. The application can effectively reduce the risk of material falling of the active material layer, ensure the transmission effect of lithium ions, reduce the risk of lithium precipitation, reduce the formation of lithium dendrites, reduce the short circuit risk caused by piercing the diaphragm, 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] The core formed by winding has bends, where stress concentrates and there is a risk of the active material layer detaching from the electrode, affecting the battery's energy density and cycle life. To prevent this, an adhesive layer is usually placed at the bends. However, the adhesive layer can affect the lithium-ion transport rate between the positive and negative electrodes, causing lithium ions to precipitate as lithium dendrites, thus impacting battery safety. Summary of the Invention

[0003] This invention provides a battery and battery device to solve the problem in the prior art where lithium ions precipitate in the form of lithium dendrites, affecting the safety performance of the battery.

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

[0005] A core formed by winding together a positive electrode, a separator, and a negative electrode, wherein at least one of the positive and negative electrode sheets is provided with an elastic coating, the electrode sheet is formed with a bent section, the electrode sheet includes a current collector and an active material layer disposed on at least one side of the current collector, and the elastic coating is at least partially coated on the surface of the active material layer at the bent section;

[0006] The areal density of the elastic coating is A mg / cm³. 2 The thickness of the elastic coating is d μm, the Vickers hardness of the current collector is k HV, and the particle size of the active particles in the active material layer is D. v50 μm, satisfying 0.01≤k / (A×d×D) v50 ≤30.07.

[0007] Beneficial effects: By coating the surface of the active material layer in the bent section of the electrode with an elastic coating, not only can the shedding of the active material layer be prevented, but a transport channel for lithium ions can also be provided. Furthermore, by adjusting k / (A×d×D) v50 The range of values ​​for ) is limited to effectively reduce the risk of material loss from the active material layer, while ensuring the transport effect of lithium ions, reducing the risk of lithium plating, reducing the formation of lithium dendrites, reducing the risk of short circuit caused by puncturing the separator, and improving the battery safety performance.

[0008] In a second aspect, the present invention also provides a battery device, comprising:

[0009] Battery box;

[0010] The aforementioned battery is disposed within the battery case. Attached Figure Description

[0011] 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.

[0012] Figure 1 This is a front view of an elastic coating according to an embodiment of the present invention;

[0013] Figure 2 for Figure 1 A side view of the elastic coating shown;

[0014] Figure 3 This is a schematic diagram showing the distribution of an elastic coating and a first electrode tab according to an embodiment of the present invention;

[0015] Figure 4 for Figure 3 The front view of the electrode sheet in its unfolded state;

[0016] Figure 5 This is a schematic diagram showing the distribution of another elastic coating and a first electrode tab according to an embodiment of the present invention;

[0017] Figure 6 for Figure 5 The front view of the electrode sheet in its unfolded state;

[0018] Figure 7 A front view of an embodiment of the present invention showing a plurality of elastic coatings disposed on an electrode sheet;

[0019] Figure 8 This is a front view of the elastic coating in an embodiment of the present invention, showing that the end of the coating does not extend beyond the edge of the active material layer.

[0020] Figure 9 This is a front view of an embodiment of the present invention, showing that the end of the elastic coating extends beyond the edge of the active material layer but does not extend beyond the edge of the current collector.

[0021] Figure 10 This is a schematic diagram of the structure of the elastic coating extending to the straight section according to an embodiment of the present invention;

[0022] Figure 11 This is a schematic diagram of the structure of the winding core according to an embodiment of the present invention;

[0023] Figure 12 A schematic diagram of a structure in which both the first and second bending sections of an embodiment of the present invention are provided with elastic coatings;

[0024] Figure 13 This is a schematic diagram of the structure of the current collector in an embodiment of the present invention, in which active material layers are provided on both opposite sides;

[0025] Figure 14 A schematic diagram of a structure in which an active material layer is provided on one side of the current collector according to an embodiment of the present invention;

[0026] Figure 15 This is a schematic cross-sectional view of the core in the direction perpendicular to the width of the electrode sheet according to an embodiment of the present invention;

[0027] Figure 16 This is a schematic diagram of the battery explosion according to an embodiment of the present invention;

[0028] Figure 17 This is a schematic diagram of the crease and elastic coating at the bending section in an embodiment of the present invention.

[0029] Explanation of reference numerals in the attached figures:

[0030] 1. Electrode; 11. Bending section; 111. Crease; 12. Current collector; 13. Active material layer; 14. Winding start end; 15. First bending section; 16. Second bending section; 17. First active material layer; 18. Second active material layer; 19. Straight section; 2. Elastic coating; 3. First tab; 31. First side; 32. Second side; 4. Separator;

[0031] 10. Core; 110. Arc area; 120. Straight area;

[0032] 20. Housing assembly; 210. Battery cover; 220. Housing body. Detailed Implementation

[0033] 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.

[0034] The following is combined Figures 1 to 17 The following describes embodiments of the present invention.

[0035] According to an embodiment of the present invention, in one aspect, a battery is provided, comprising:

[0036] The core 10 is formed by winding a positive electrode sheet, a separator 4 and a negative electrode sheet stacked together. At least one of the positive and negative electrode sheets 1 is provided with an elastic coating 2. The electrode sheet 1 is formed with a bent section 11. The electrode sheet 1 includes a current collector 12 and an active material layer 13 disposed on at least one side of the current collector 12. The elastic coating 2 is at least partially coated on the surface of the active material layer 13 at the bent section 11.

[0037] The areal density of elastic coating 2 is A mg / cm³. 2 The thickness of the elastic coating 2 is d μm, the Vickers hardness of the current collector 12 is k HV, and the particle size of the active particles in the active material layer 13 is D. v50 μm, satisfying 0.01≤k / (A×d×D) v50 ≤30.07.

[0038] The battery using this embodiment, by coating the surface of the active material layer 13 of the bent section 11 of the electrode 1 with an elastic coating 2, not only can the active material layer 13 be prevented from shedding, but it can also provide a transport channel for lithium ions. Furthermore, by adjusting k / (A×d×D) v50 The range of values ​​for ) is limited to effectively reduce the risk of material loss from the active material layer 13, while ensuring the transport effect of lithium ions, reducing the risk of lithium plating, reducing the formation of lithium dendrites, reducing the risk of short circuit caused by puncturing the separator, and improving the battery safety performance.

[0039] It is worth noting that if k / (A×d×D) v50 If the value of k / (A×d×D) is too small, it will affect the transport of lithium ions, easily leading to the risk of lithium plating, which in turn can cause lithium dendrites to form and puncture the separator, causing a short circuit between the positive and negative electrodes and affecting the safety performance of the battery. v50 If the value of ) is too large, it will increase the risk of material loss in the active material layer 13 and affect the cycle life of the battery.

[0040] Optional, k / (A×d×D) v50 The value of ) can be any one of the following: 0.01, 0.02, 0.05, 0.1, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 15.66, 18, 20, 22, 25, 28, 30.07, or a value between any two of these values.

[0041] Preferably, the areal density A of the elastic coating 2 is 1 mg / cm³. 2 The thickness d μm of the elastic coating 2, the Vickers hardness k HV of the current collector 12, and the particle size D of the active particles in the active material layer 13 are also considered. v50 μm satisfies 0.05≤k / (A×d×D) v50 ≤15.66.

[0042] It is worth noting that in related technologies, an adhesive layer is bonded to the surface of the active material layer 13 to prevent material shedding. However, research has found that the adhesive layer is relatively dense, which can significantly affect lithium-ion transport and easily lead to lithium plating, which in turn can cause lithium dendrites to puncture the separator, resulting in short circuits between the positive and negative electrodes. Therefore, in this embodiment, an elastic coating 2 is formed on the surface of the active material layer 13. The elastic coating 2 prevents the active material layer 13 from shedding, and the pores formed inside the elastic coating 2 serve as lithium-ion transport channels, reducing the risk of lithium plating and improving battery safety performance.

[0043] In this embodiment, the areal density A of the elastic coating 2 is [mg / cm²]. 2 The following methods can be used for regulation:

[0044] Method (1): Adjust the surface density by adjusting the coating speed of the slurry. Slowing down the coating speed increases the surface density, and increasing the coating speed decreases the surface density.

[0045] Method (II): Adjust the areal density by adjusting the solid content in the positive or negative electrode slurry. Increasing the solid content increases the areal density, and decreasing the solid content decreases the areal density.

[0046] In this embodiment, the Vickers hardness k HV of the current collector 12 can be controlled by the following means:

[0047] For copper foil, Method (1) involves adjusting the annealing temperature during the copper foil preparation process; the higher the temperature, the lower the Vickers hardness. Method (2) involves adjusting the Vickers hardness of the copper foil by incorporating trace elements such as oxygen and phosphorus.

[0048] For aluminum foil, there are two methods: (1) Adjusting the Vickers hardness by adjusting the cold rolling deformation rate; the higher the cold rolling deformation rate, the higher the Vickers hardness. (2) Adjusting the Vickers hardness by adjusting the grain size; the smaller the grain size, the higher the Vickers hardness.

[0049] In this embodiment, the particle size of the active particles in the active material layer 13 is D. v50 μm can be controlled using the following methods:

[0050] Method (1): Adjusting D by regulating the sintering temperature v50 The higher the sintering temperature, the more D v50 The larger.

[0051] Method (II) Adjusting D by adjusting the rotation speed of the pulverizing equipment after sintering v50 The higher the rotational speed, the more D v50 The smaller.

[0052] In one embodiment, the elastic coating 2 comprises an adhesive and a filler.

[0053] The adhesives include styrene-butadiene copolymers, acrylate-styrene-butadiene copolymers, acrylonitrile-butadiene copolymers, acrylonitrile-butadiene-styrene copolymers, acrylic rubber, butyl rubber, styrene-butadiene rubber, fluororubber, polyethylene, polypropylene, ethylene propylene diene monomer (EPDM) rubber, ethylene propylene diene monomer (EPDM) rubber, polyethylene oxide, polyepoxychloropropane, polyvinylpyrrolidone, polyphosphazene, polyacrylonitrile, polystyrene, polyvinylpyridine, chlorosulfonated polyethylene, polyester resin, acrylic resin, phenolic resin, epoxy resin, fluorocarbon resin, polyvinyl alcohol, hydroxypropyl methylcellulose, hydroxypropyl cellulose, diacetylcellulose, polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, polytetrafluoroethylene, polyacrylic acid, polyimide, polyamide-imide, polyimide-polyamide-imide copolymer, and one or more polymers in which the aforementioned polymers are partially or completely substituted by alkali metals.

[0054] The filler includes one or more of ceramics, silicates, minerals, and glass, and optionally includes one or more of alumina, zinc oxide, silicon oxide, titanium oxide, zirconium oxide, barium oxide, calcium oxide, magnesium oxide, nickel oxide, tin oxide, cerium oxide, yttrium oxide, hafnium oxide, aluminum hydroxide, magnesium hydroxide, silicon carbide, boron carbide, aluminum nitride, silicon nitride, boron nitride, magnesium fluoride, calcium fluoride, barium fluoride, barium sulfate, magnesium aluminum silicate, lithium magnesium silicate, sodium magnesium silicate, boehmite, mica, bentonite, hydropyrite, kaolin, and talc.

[0055] In one embodiment, the areal density A of the elastic coating 2 is [amount in mg / cm³]. 2 Meets 0.05 mg / cm 2 ≤A mg / cm 2 ≤14mg / cm 2 This design ensures protection for the active material layer 13 while reducing the risk of lithium plating in the battery.

[0056] It is worth noting that if the value of A is too large, the elastic coating 2 will be too dense, affecting the lithium-ion transport effect and easily causing lithium plating problems. This can lead to lithium dendrites piercing the separator, causing short circuits between the positive and negative electrodes and affecting the battery's safety performance. If the value of A is too small, the internal pores of the elastic coating 2 will be too large, resulting in weakened protective performance of the elastic coating 2 and a risk of material shedding.

[0057] Optionally, A can take any value from 0.05, 0.1, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or a value between any two values.

[0058] Preferably, the areal density A of the elastic coating 2 is 1 mg / cm³. 2 Meets 0.1 mg / cm 2 ≤A mg / cm 2 ≤12 mg / cm 2 .

[0059] Preferably, the areal density A of the elastic coating 2 is 1 mg / cm³. 2 Meets 1mg / cm 2 ≤A mg / cm 2 ≤5mg / cm 2 .

[0060] In one embodiment, such as Figure 2 As shown, the thickness d μm of the elastic coating 2 satisfies 5μm≤d μm≤80μm. This setting ensures the protection of the active material layer 13 while reducing the risk of lithium plating in the battery.

[0061] It is worth noting that if the value of d is too small, the protective effect of the elastic coating 2 on the active material layer 13 will be poor, which may easily lead to material shedding. If the value of d is too large, it will affect the lithium-ion transport effect, which may easily lead to lithium plating, and then cause lithium dendrites to pierce the separator, resulting in short circuit between the positive and negative electrodes, thus affecting the safety performance of the battery.

[0062] Optionally, d can take any value from 5, 8, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, or a value between any two values.

[0063] Preferably, the thickness d μm of the elastic coating 2 satisfies 10μm≤d μm≤75μm.

[0064] Preferably, when the elastic coating 2 is coated on the surface of the positive electrode active material layer 3, the thickness d μm of the elastic coating 2 satisfies 8μm≤d μm≤30μm.

[0065] In one embodiment, such as Figure 1 As shown, along the length of electrode 1, the width of the elastic coating 2 is b mm, satisfying 10 mm ≤ b mm ≤ 35 mm. This configuration avoids material shedding from the active material layer 13 while reducing the risk of lithium plating in the battery.

[0066] It is worth noting that if the value of b is too small, the coverage area of ​​the bending section 11 will be too small, and there is a risk of material loss in the uncovered areas of the bending section 11. If the value of b is too large, the coverage area of ​​the bending section 11 will be too large, affecting the lithium-ion transport efficiency and exacerbating the lithium plating problem in the battery.

[0067] Optionally, b can take any value from 10, 12, 15, 18, 20, 22, 25, 28, 30, 32, 35 or a value between any two values.

[0068] In one embodiment, such as Figure 3 and Figure 4 As shown, the electrode 1 has a winding start end 14, and the electrode 1 extends along its width direction to form a first electrode tab 3. The first electrode tab 3 is disposed near the winding start end 14, and the side of the first electrode tab 3 near the winding start end 14 is a first side edge 31. At least one elastic coating 2 is disposed between the winding start end 14 and the first side edge 31.

[0069] It is worth noting that the first tab 3 refers to the first tab arranged along the length of the electrode sheet 1, starting from the winding start end 14. Therefore, at least one bending section 11 is provided between the winding start end 14 and the first tab 3 along the length of the electrode sheet 1.

[0070] Furthermore, in one embodiment, such as Figure 4 As shown, along the length direction of electrode 1, the distance between the first side 31 and the edge of the elastic coating 2 is c1 mm, which satisfies 15 mm ≤ c1 mm ≤ 250 mm.

[0071] It is worth noting that the current near the winding start end 14 of electrode 1 needs to be drawn from the first tab 3. At this time, the current path is relatively long, resulting in significant heat generation. Simultaneously, the first tab 3 is also a heat-generating end. Therefore, it is necessary to control the distance between the first tab 3 and the elastic coating 2 within a suitable range. If the value of c1 is too small, i.e., the distance is too small, heat is easily transferred to the elastic coating 2, causing the elastic coating 2 to be affected by heat and potentially leading to its detachment, which in turn causes the active material layer 13 to detach. If the value of c1 is too large, i.e., the distance is too large, the current path becomes too long, increasing the battery's internal resistance, affecting ion transport, and easily triggering lithium plating problems.

[0072] Optionally, c1 can be any value from 15, 20, 25, 30, 50, 70, 80, 100, 120, 150, 180, 200, 220, 250, or a value between any two values.

[0073] Furthermore, in one embodiment, the distance c1 mm between the first side 31 and the edge of the elastic coating 2 and the width b mm of the elastic coating 2 satisfy c1 mm ≤ 200 mm and 15 mm ≤ b mm ≤ 35 mm.

[0074] It is worth noting that when the elastic coating 2 and the first tab 3 are close to each other, by further controlling the width of the elastic coating 2, the stability of the elastic coating 2 on the active material layer 13 can be improved, thus preventing the elastic coating 2 from falling off and causing the active material layer 13 to fall off.

[0075] As an alternative implementation, in another embodiment, such as Figure 5 and Figure 6 As shown, the electrode 1 has a winding start end 14, and the electrode 1 extends along its width direction to form a first electrode tab 3. The first electrode tab 3 is disposed near the winding start end 14, and the side of the first electrode tab 3 away from the winding start end 14 is a second side 32. An elastic coating 2 closest to the winding start end 14 is located on the side of the second side 32 away from the winding start end 14.

[0076] That is, in an alternative implementation, no bending section 11 is provided between the winding start end 14 and the first electrode tab 3.

[0077] Furthermore, in the above alternative implementations, such as Figure 6 As shown, along the length direction of electrode 1, the distance between the second side 32 and the edge of the elastic coating 2 is c2 mm, which satisfies 15 mm ≤ c2 mm ≤ 225 mm.

[0078] It is worth noting that the width direction of electrode 1 is perpendicular to the length direction of electrode 1, and the width direction of electrode 1 is the direction in which the tab is led out.

[0079] Optionally, c2 can be any value from 15, 20, 25, 30, 50, 70, 80, 100, 120, 150, 180, 200, 220, 225 or a value between any two values.

[0080] In one embodiment, such as Figure 8 As shown, along the width direction of the electrode 1, the end of the elastic coating 2 does not extend beyond the edge of the active material layer 13, and the distance between the end of the elastic coating 2 and the edge of the active material layer 13 is e mm, satisfying 1 mm ≤ e mm ≤ 15 mm. That is, the elastic coating 2 is completely located within the active material layer 13, and the elastic coating 2 does not extend beyond the active material layer 13. This arrangement reduces the risk of material shedding from the active material layer 13 while also reducing the risk of lithium plating in the battery.

[0081] It is worth noting that if the value of e is too large, the coverage area of ​​the elastic coating 2 on the bending section 11 may be too small, posing a risk of material loss in the uncovered areas of the bending section 11. If the value of e is too large, the coverage area of ​​the bending section 11 may be too large, affecting the lithium-ion transport efficiency and exacerbating the lithium plating problem in the battery.

[0082] Optionally, the value of e can be any one of the following: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, or a value between any two of these.

[0083] As an alternative implementation, in another embodiment, such as Figure 9 As shown, along the width direction of electrode 1, the end of elastic coating 2 extends beyond the edge of active material layer 13 by a width of m mm, and the edge of current collector 12 extends beyond the edge of active material layer 13 by a width of n mm, satisfying m ≤ n. That is, the coating range of elastic coating 2 extends beyond active material layer 13, but does not extend beyond current collector 12.

[0084] Furthermore, in the alternative embodiments described above, the width of the end of the elastic coating 2 extending beyond the edge of the active material layer 13 is m mm, and the width of the edge of the current collector 12 extending beyond the edge of the active material layer 13 is n mm, satisfying 0.01 ≤ m / n ≤ 1. This configuration improves the protection of the active material layer 13 while reducing the risk of lithium plating.

[0085] It is worth noting that if the value of m / n is too large, the elastic coating 2 will cover too large an area of ​​the current collector 12, affecting the heat dissipation effect of the electrode 1, and thus affecting the lithium-ion transport effect, leading to the risk of lithium plating. If the value of m / n is too small, the protective effect of the elastic coating 2 on the edge of the active material layer 13 will be reduced, posing a risk of material shedding.

[0086] Optionally, m / n can take any value from 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 1, or a value between any two values.

[0087] Specifically, the width m mm of the end of the elastic coating 2 extending beyond the edge of the active material layer 13 satisfies 0.1 mm ≤ m mm ≤ 2.6 mm; the width n mm of the edge of the current collector 12 extending beyond the edge of the active material layer 13 satisfies 1 mm ≤ n mm ≤ 10 mm.

[0088] Optionally, m can take any value from 0.1, 0.3, 0.5, 0.8, 1, 1.2, 1.5, 1.8, 2, 2.2, 2.5, 2.6 or a value between any two values.

[0089] Optionally, n can take any value from 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or a value between any two values.

[0090] In one embodiment, such as Figure 12 As shown, elastic coatings 2 are provided on both opposite sides of electrode 1, and the value of k HV satisfies 30HV≤k HV≤65HV.

[0091] It should be noted that when elastic coating 2 is provided on both opposite sides of electrode 1, it will make it more difficult to wind electrode 1. Therefore, the hardness of current collector 12 needs to be further reduced in order to make electrode 1 easier to wind and form.

[0092] In one embodiment, such as Figure 12 As shown, the electrode 1 has a first bending section 15 and a second bending section 16 arranged at relative intervals, and both the first bending section 15 and the second bending section 16 are provided with an elastic coating 2.

[0093] It is worth noting that, such as Figure 11 and Figure 12 As shown, along the length of the electrode 1, the electrode 1 also has a straight section 19 connected to the bending section 11. The core 10 has two arcuate regions 110 spaced apart from each other and a straight section 120 connecting the two arcuate regions 110. The bending section 11 is used to form the arcuate region 110 (specifically, the first bending section 15 is used to form one arcuate region 110, and the second bending section 16 is used to form another arcuate region 110), and the straight section 19 is used to form the straight section 120. Furthermore, both arcuate regions 110 are provided with an elastic coating 2.

[0094] In one embodiment, the electrode 1 has a winding start end 14, and an elastic coating 2 is provided on the first bending segment 11 closest to the winding start end 14. Further, in one embodiment, the electrode 1 is wound into several turns, and the elastic coating 2 is provided within five turns closest to the winding start end 14 of the electrode 1. It is worth noting that the electrode 1 experiences greater stress near the inner turns after winding; therefore, providing the elastic coating 2 on the inner turns of the electrode 1 reduces the risk of material loss.

[0095] Optionally, the elastic coating 2 can be provided within five turns of the starting end 14 of the winding near the electrode 1, or the elastic coating 2 can be provided only in the first turn or the first two turns.

[0096] It is worth noting that the stress in the first five turns of the wound cell near the starting end 14 is relatively greater than that in the outer turns. Therefore, an elastic coating 2 can be applied to prevent material loss, which also helps to minimize the risk of lithium plating. Of course, to better prevent material loss, an elastic coating 2 can be applied to all bending sections 11.

[0097] In one embodiment, the electrode 1 is wound in several turns. A crease 111 is formed at the bending section 11 of the first turn near the starting end 14 of the winding of the electrode 1. The elastic coating 2 covers the crease 111. The stress is most concentrated in the first turn of the wound cell, which will form the crease 111 and has a greater risk of material falling off. Covering the crease 111 with the elastic coating 2 can reduce the risk of material falling off at the crease 111.

[0098] Furthermore, such as Figure 17 As shown, along the length of electrode 1, the edge of the elastic coating 2 extends beyond the crease 111 by a distance of h mm, satisfying h mm ≥ 3 mm. It is worth noting that if the value of h is too small, material may easily fall off at the crease 111; in addition, if the value of h is too large, it may easily cause lithium plating problems. Therefore, the value of h does not need to be too large.

[0099] In one embodiment, such as Figure 7 As shown, several elastic coatings 2 are spaced apart along the length of the electrode 1, with a distance of f mm between adjacent elastic coatings 2, satisfying 110 mm ≤ f mm ≤ 300 mm. This arrangement avoids material shedding from the active material layer 13 while reducing the risk of lithium plating in the battery.

[0100] It is worth noting that if the value of f is too large, the coverage area of ​​the elastic coating 2 over the bending section 11 may be too small, posing a risk of material loss in the uncovered areas of the bending section 11. If the value of f is too small, the coverage area of ​​the elastic coating 2 over the bending section 11 may be too large, affecting the lithium-ion transport efficiency and exacerbating the lithium plating problem in the battery.

[0101] Optionally, f can take any value from 110, 120, 130, 140, 150, 180, 200, 220, 250, 280, 290, 300, or a value between any two values.

[0102] In one embodiment, such as Figure 11 As shown, the core 10 has two relatively spaced arc regions 110 and a straight region 120 connecting the two arc regions 110. Along the extending direction of the straight region 120, the width of the core 10 is L mm, satisfying 0.025≤b / L≤0.25. This configuration avoids the shedding of the active material layer 13 while reducing the risk of lithium plating in the battery.

[0103] It is worth noting that if the value of b / L is too large, the coverage area of ​​the elastic coating 2 on the bending section 11 may be too large, affecting the lithium-ion transport efficiency and exacerbating the lithium plating problem. If the value of b / L is too small, when the width of the core 10 is large, the expansion of the cell during battery use will be greater, and the coverage area of ​​the elastic coating 2 on the bending section 11 will be too small, posing a risk of material shedding from the uncovered areas of the bending section 11.

[0104] Optionally, b / L can be any value from 0.025, 0.05, 0.075, 0.1, 0.125, 0.15, 0.175, 0.2, 0.225, 0.25, or a value between any two values.

[0105] Specifically, the width L mm of the core 10 satisfies 140 mm ≤ L mm ≤ 400 mm.

[0106] In one embodiment, the particle size D of the active particles in the active material layer 13 is... v50 μm satisfies 0.2μm≤D v50 μm≤30μm. This setting reduces both the risk of material shedding and the risk of lithium plating.

[0107] It is worth noting that if D v50 If the value of D is too large, it will result in an excessively long lithium-ion transport path, making lithium plating more likely and forming lithium dendrites. This poses a risk of puncturing the separator, causing a short circuit between the positive and negative electrodes, and affecting the battery's safety performance. If D v50 If the value is too small, the fixation effect of the active material layer 13 and the current collector 12 will be poor, and the problem of material falling off is likely to occur.

[0108] Optional, D v50 The value can be any one of 0.2, 1, 2, 4, 5, 8, 10, 12, 15, 18, 20, 22, 25, 28, 30, or a value between any two values.

[0109] Preferably, the particle size D of the active particles in the active material layer 13 is... v50 μm satisfies 2μm≤D v50 μm≤28μm.

[0110] Preferably, when the active material layer 13 is a positive electrode active material layer, the particle size D of the active particles in the active material layer 13 is... v50 μm satisfies 0.5μm≤D v50 μm≤10μm.

[0111] In one embodiment, the elastic coating 2 is disposed on the positive electrode sheet, D v50 The value of μm satisfies 0.2μm≤D v50 μm≤20μm.

[0112] It is worth noting that the current collector 12 of the positive electrode is usually made of aluminum foil, which has high resistance and generates a lot of heat, easily affecting the lithium-ion transport efficiency. Therefore, by making D v50 The value of is further reduced to improve the lithium-ion transport efficiency.

[0113] Furthermore, for ternary materials, D v50 The value of μm satisfies 2μm≤D v50 μm≤20μm. For lithium iron phosphate materials, D v50 The value of μm satisfies 0.2μm≤D v50 μm≤2μm.

[0114] Additionally, in one embodiment, for the negative electrode, D v50 The value of μm satisfies 7μm≤D v50 μm≤30μm.

[0115] Furthermore, for graphite materials, D v50 The value of μm satisfies 10μm≤D v50 μm≤30μm. For silicon-carbon materials, D v50 The value of μm satisfies 7μm≤D v50 μm≤15μm.

[0116] In one embodiment, such as Figure 13 As shown, active material layers 13 are provided on both opposite sides of the current collector 12.

[0117] Of course, in other alternative implementations, such as Figure 14 As shown, the active material layer 13 can also be provided only on one side of the current collector 12 along the thickness direction.

[0118] Furthermore, in one embodiment, the active material layers 13 located on opposite sides of the current collector 12 are a first active material layer 17 and a second active material layer 18, respectively, wherein the particle size of the active particles in the first active material layer 17 is D. v50-1 μm, the particle size of the active particles in the second active material layer 18 is D v50-2 μm, satisfying 3≤|D v50-1 -D v50-2 |≤28.8. This setting ensures the uniformity of both sides of electrode 1.

[0119] In one embodiment, such as Figure 10 As shown, along the length of the electrode 1, the electrode 1 also has a straight section 19 connected to the bent section 11, and the elastic coating 2 extends to the straight section 19. This arrangement ensures that the bent section 11 is completely covered along the length of the electrode 1, avoiding the risk of the bent section 11 falling off.

[0120] Furthermore, in one embodiment, such as Figure 10 As shown, along the length of electrode 1, the elastic coating 2 extends to the straight section 19 with a width of g mm, satisfying g mm ≤ 16 mm. This setting reduces the risk of lithium plating in the battery.

[0121] It is worth noting that if the value of g 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.

[0122] Optionally, g can take any value from 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 or a value between any two values.

[0123] In one embodiment, the Vickers hardness k HV of the current collector 12 satisfies 30 HV≤k HV≤70HV.

[0124] It is worth noting that if the value of k is too large, the winding of electrode 1 will be difficult, and the stress at the bending section 11 will be relatively large, which may easily lead to material loss. If the value of k is too small, wrinkles may easily occur during the rolling process of electrode 1.

[0125] Optionally, k can take any value from 30, 32, 35, 38, 40, 42, 45, 48, 50, 52, 55, 58, 60, 62, 65, 68, 70, or a value between any two values.

[0126] Preferably, the Vickers hardness k HV of the current collector 12 satisfies 32 HV≤k HV≤65 HV.

[0127] Preferably, when the current collector 12 is a positive current collector, the Vickers hardness k HV of the current collector 12 satisfies 50 HV≤k HV≤70 HV.

[0128] In one embodiment, the battery further includes a housing assembly and an electrolyte, with the core 10 and the electrolyte both disposed within the housing assembly, and the ionic conductivity of the electrolyte ranging from 0.8 mS / cm to 20 mS / cm.

[0129] In one embodiment, the electrolyte contains at least one of fluoroethylene carbonate, vinylene carbonate, ethylene sulfate, ethylene disulfate, ethylene sulfite, propylene sulfite, and lithium difluorooxalate borate. This configuration improves the overall ion transport rate of the electrolyte, shortens the battery charge / discharge time, and avoids the risk of lithium plating at the bending section of the electrode.

[0130] It is worth noting that the electrolyte includes a solvent, additives, and a lithium salt. The solvent includes at least one of the following: ethylene carbonate (EC), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), diethyl carbonate (DEC), propylene carbonate (PC), ethyl acetate (EA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), and methyl acetate (MA). The additives include at least one of the following: methylene disulfonate (MMDS), vinylene carbonate (VC), 1,3-propanesulfonate lactone (PS), fluoroethylene carbonate (FEC), vinyl sulfate (DTD), propylene sulfonate lactone (PST), tris(trimethylsilane) phosphate (TMSP), tris(trimethylsilane) borate (TMSB), and hexamethylene diisocyanate (HDI). The lithium salt includes at least one of the following: lithium hexafluorophosphate, lithium difluorophosphate, lithium difluorooxalate borate, and lithium bis(fluorosulfonyl)imide.

[0131] Furthermore, such as Figure 16 As shown, the housing assembly 20 includes a battery cover 210 and a housing body 220. At least one end of the housing body 220 is open. The battery cover 210 is connected to the housing body 220 and seals the opening. The battery cover 210 and the housing body 220 enclose a receiving space, and the core 10 is disposed in the receiving space.

[0132] According to an embodiment of the present invention, in another aspect, a battery device is also provided, comprising:

[0133] Battery box;

[0134] The aforementioned battery is housed inside a battery compartment.

[0135] It is worth noting that battery devices can serve as the operating power source for electrical devices, or as the driving power source for electrical devices, replacing or partially replacing fuel or natural gas to provide driving power for vehicles. Electrical devices include: energy storage devices, electric ships, aircraft, laptops, power tools, electric bicycles, electric motorcycles, electric cars, military equipment, aerospace, and many other technological fields.

[0136] 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.

[0137] The preparation of the example battery and the comparative battery includes the following steps:

[0138] (1) Preparation of the positive electrode:

[0139] 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, and an elastic coating is applied. After drying at room temperature, it is transferred to an oven for further drying. Then, 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).

[0140] (2) Preparation of negative electrode:

[0141] 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, and an elastic coating is applied. After drying at room temperature, it is transferred to an oven for further drying. Then, it is cold-pressed and slit to obtain the negative electrode sheet. The ratio of negative electrode active material: conductive agent: thickener: binder satisfies (90~96): (4~2): (2~1): (4~1).

[0142] (3) Preparation of electrolyte:

[0143] 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 initial electrolyte with a concentration of 1 mol / L. Ethyl sulfate (DTD) was added to the initial electrolyte to obtain the final electrolyte. The mass percentage of ethylene sulfate (DTD) was 0.2% to 3.0%.

[0144] (4) Preparation of the diaphragm:

[0145] Polyethylene film is selected as the diaphragm.

[0146] (5) Preparation of lithium-ion batteries:

[0147] The aforementioned positive electrode sheet, separator, and negative electrode sheet are stacked in sequence and wound to form a battery cell. The battery cell is then placed in a battery casing, which is a prismatic casing. The battery is dried, injected with electrolyte, and then encapsulated, allowed to stand, formed, and capacitated to obtain a lithium-ion battery. 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 materials, including artificial graphite, natural graphite, silicon carbide, silicon oxide, and lithium titanate.

[0148] 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:

[0149] Performance 1: Battery capacity retention rate

[0150] Following the battery fabrication method described above, corresponding lithium-ion batteries were prepared for each embodiment and comparative example. The differences between the batteries in the embodiments and the batteries in the comparative examples lie in A, k, d, and D. v50 The values ​​for are shown in Table 1, and the rest of the structure is the same. The lithium-ion battery is 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 drops to 0.05C. After standing for 5 minutes, the battery is discharged with a constant current of 0.33C to the lower limit voltage. The above steps are repeated for a total of 3 charge-discharge cycles. The discharge capacity Q1 of the third charge-discharge cycle is obtained and is taken as the fixed capacity.

[0151] 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 formula for calculating the battery capacity retention rate is "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; otherwise, it is considered qualified.

[0152] 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.

[0153] 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.

[0154] Performance 2: Battery Lithium Plating

[0155] Following the battery fabrication method described above, corresponding lithium-ion batteries were prepared for each embodiment and comparative example. The differences between the batteries in the embodiments and the batteries in the comparative examples lie in A, k, d, and D. v50 The values ​​for are shown in Table 1; the rest of the structure is the same. The lithium-ion battery is charged at room temperature (25°C) with a constant current of 0.33C to the upper limit voltage. Then, it is charged with a constant voltage 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. 2000 cycles are performed. Then, the lithium-ion battery is charged at 0.33C to the upper limit voltage, with the cutoff current less than or equal to 0.05C, resulting in a fully charged battery.

[0156] Disassemble the battery, then remove the electrodes and observe the lithium plating on the surface of the negative electrode in the bending section. The portion where the projection of a single elastic coating overlaps with the negative electrode is the first region, and the lithium plating area of ​​the first region is measured and recorded as S1. The area of ​​the single elastic coating in the first region of the active material layer in the bending section is recorded as S2. According to the formula, the percentage of the lithium plating area on the surface of the first region = (S1 / S2) × 100%, the percentage of the lithium plating area on the surface of the first region is calculated. If the lithium plating area on the surface of the first region is less than 10%, it is considered slight lithium plating; if the lithium plating area on the surface of the first region is between 10% and 50%, it is considered moderate lithium plating; if the lithium plating area on the surface of the first region is greater than 50%, it is considered severe lithium plating. Severe lithium plating is unacceptable.

[0157] 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.

[0158] 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.

[0159] The test method for the areal density A of the elastic coating can be carried out using the following steps:

[0160] (1) Pretreatment: Discharge the battery to the lower limit voltage at 0.33C, disassemble the electrode with elastic coating, soak the electrode in dimethyl carbonate (DMC) solution for 4 hours, and air dry.

[0161] When the positive electrode active material of the battery is lithium nickel cobalt manganese oxide, lithium iron phosphate, or lithium manganese iron phosphate, the lower limit voltage is 2.5V; when the positive electrode active material of the battery is lithium nickel manganese oxide, the lower limit voltage is 3.5V.

[0162] (2) Use a punching machine to punch the pretreated electrode sheet into circular pieces of fixed area with a radius of 3mm. Take six circular pieces from the electrode sheet without elastic coating, weigh them, and calculate the average value, which is recorded as M1. Take six circular pieces from the electrode sheet with elastic coating, weigh them, and calculate the average value, which is recorded as M2. Calculate the areal density of the elastic coating according to the following formula: = (M2 - M1) / (3.14 × 3 2 ).

[0163] The following steps can be used to test the thickness d of the elastic coating:

[0164] The battery was discharged to the lower limit voltage at 0.33C, the battery was disassembled, and the electrode with the elastic coating was removed. The electrode was dried at 60℃ for 3 hours, and the thickness d μm of the elastic coating was measured using a scanning electron microscope.

[0165] When the positive electrode active material of the battery is lithium nickel cobalt manganese oxide, lithium iron phosphate, or lithium manganese iron phosphate, the lower limit voltage is 2.5V; when the positive electrode active material of the battery is lithium nickel manganese oxide, the lower limit voltage is 3.5V.

[0166] Regarding the particle size D of the active particles in the active material layer v50 The testing method can be implemented using the following steps:

[0167] The battery was discharged to its lower limit voltage at 0.33C. The battery was then disassembled, and the positive and negative electrode plates were removed. The positive and negative electrode plates were separately immersed in dimethyl carbonate (DMC) solution for 4 hours. They were then dried at 80℃ for 6 hours. The positive and negative electrode plates were then scraped to obtain positive and negative electrode powders, respectively. The particle size distribution of the positive and negative electrode powders was measured using a laser particle size analyzer (Mastersizer 3000) according to the laser diffraction method for particle size distribution (specific steps refer to GB / T19077-2016). The particle size corresponding to a cumulative particle size distribution percentage reaching 50% is defined as D. v50 .

[0168] When the positive electrode active material of the battery is lithium nickel cobalt manganese oxide, lithium iron phosphate, or lithium manganese iron phosphate, the lower limit voltage is 2.5V; when the positive electrode active material of the battery is lithium nickel manganese oxide, the lower limit voltage is 3.5V.

[0169] The test method for the Vickers hardness k of the current collector can be carried out using the following steps:

[0170] (1) Pretreatment: Discharge the battery to the lower limit voltage at 0.33C, disassemble the electrode with elastic coating, soak the electrode in dimethyl carbonate (DMC) solution for 4 hours, and air dry.

[0171] When the positive electrode active material of the battery is lithium nickel cobalt manganese oxide, lithium iron phosphate, or lithium manganese iron phosphate, the lower limit voltage is 2.5V; when the positive electrode active material of the battery is lithium nickel manganese oxide, the lower limit voltage is 3.5V.

[0172] (2) After wiping the pretreated electrode with alcohol to remove the elastic coating and active material layer on the surface of the current collector, the current collector sample is obtained. The current collector sample is placed in a metallographic thermal mounting machine, wood glue powder is poured in, and it is heated at a rate of 150℃ / 10min. The copper foil sample (50g weight) is pressed in with the prismatic indenter of the Vickers hardness tester. The lengths of the two diagonals are optically measured, and the corresponding Vickers hardness is obtained according to the Vickers hardness calculation formula.

[0173] Table 1:

[0174]

[0175] As can be seen from Table 1, in Examples 1 to 16, k / (A×d×D) v50 The values ​​of ) are all in the range of 0.01 to 30.07. Therefore, the batteries of Examples 1 to 16 have a cycle count of not less than 1200 cycles and the batteries do not have serious lithium plating problems.

[0176] As can be seen from Table 1, in Comparative Example 1 and Comparative Example 4, k / (A×d×D) v50 The value of ) is not in the range of 0.01 to 30.07 and is greater than 30.07. Therefore, for the batteries of Comparative Example 1 and Comparative Example 4, the number of battery cycles is less than 1200 cycles, and the battery capacity retention rate test is unqualified.

[0177] As can be seen from Table 1, in Comparative Example 2 and Comparative Example 3, k / (A×d×D) v50 The value of ) is not in the range of 0.01 to 30.07 and is less than 0.01. Therefore, the batteries of Comparative Example 2 and Comparative Example 3 have serious lithium plating problems.

[0178] The following defines and explains some of the terms used in this application.

[0179] The positive electrode is one of the core components in a battery that carries the positive electrode active material. During charging, metal ions (e.g., lithium ions in a lithium battery) are released from the positive electrode active material (oxidation reaction), migrate through the electrolyte, and intercalate into the negative electrode. During discharging, metal ions (e.g., lithium ions in a lithium battery) are released from the negative electrode and intercalate into the positive electrode active material (reduction reaction), thus realizing the storage and release of lithium ions.

[0180] A positive electrode generally includes a positive current collector 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: a positive active material, a conductive agent, and a binder. The positive active material includes, but is not limited to, at least one of the following: lithium phosphates, lithium transition metal oxides and their respective modified compounds, or other conventional materials that can be used as positive active materials for batteries. These positive active materials can be used alone or in combination. The lithium phosphates include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also abbreviated as LFP)), lithium iron phosphate and carbon composites, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate and carbon composites, lithium iron manganese phosphate, and lithium iron manganese phosphate and carbon composites. Lithium transition metal oxides include, but are not limited to, at least one of 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, lithium nickel cobalt manganese oxides, lithium nickel cobalt aluminum oxides, and their modified compounds. Conductive agents include, but are not limited to, one or more combinations of graphite, superconducting carbon, carbon black (such as acetylene black, Ketjen black, Super P, etc.), carbon nanotubes, graphene, and carbon nanofibers. Binders include, but are not limited to, one or more combinations of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, fluorinated acrylate resins, styrene-butadiene rubber, polyacrylic acid, sodium polyacrylate, polyacrylamide, polyvinyl alcohol, sodium alginate, polymethacrylic acid, and carboxymethyl chitosan.

[0181] For the negative electrode, 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 the 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 the external circuit to maintain charge balance, thus achieving energy storage and release.

[0182] The negative electrode sheet includes a negative electrode current collector and a negative electrode active layer disposed on at least one surface of the negative electrode current collector. The negative electrode current collector is a conductive metal foil, which can be made of stainless steel, copper, aluminum, nickel, carbon electrodes, carbon, nickel, or titanium with a silver-plated surface. A 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, copper, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material substrate (such as polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.). The negative electrode active layer includes a negative electrode active material, a conductive agent, and a binder. The negative electrode active material can be a carbon-based material such as graphite, porous carbon, hard carbon, soft carbon, or mesophase carbon microspheres, or a silicon-based material such as elemental silicon, silicon oxides, silicon-carbon composites, or silicon-nitrogen composites. The conductive agent can be conductive carbon black, carbon nanotubes, etc., and the binder can be styrene-butadiene rubber, polyacrylic acid, etc.

[0183] A battery cell is the component in a battery where electrochemical reactions occur; it is the smallest unit in a battery capable of carrying out electrochemical reactions such as charging and discharging.

[0184] A battery cell is the basic unit of a battery, typically consisting of a positive electrode, a negative electrode, and a separator. Lithium-ion cells primarily function by the movement of lithium ions between the positive and negative electrodes. In cylindrical cells, a three-layer thin-film structure is wound into a cylindrical electrode assembly, while in cuboid cells, the thin-film structure is wound or stacked into an electrode assembly with a roughly cuboid shape.

[0185] 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 metal material with good conductivity (such as copper, aluminum, copper or nickel, or a composite current collector containing insulating material, etc.).

[0186] A separator is placed between the positive and negative electrode plates to separate them and prevent them from short-circuiting due to contact.

[0187] 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.

[0188] 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: A core (10) is formed by winding a positive electrode, a separator (4) and a negative electrode in a stacked arrangement. At least one electrode (1) of the positive electrode and the negative electrode is provided with an elastic coating (2). The electrode (1) is formed with a bent section (11). The electrode (1) includes a current collector (12) and an active material layer (13) disposed on at least one side of the current collector (12). The elastic coating (2) is at least partially coated on the surface of the active material layer (13) at the bent section (11). The areal density of the elastic coating (2) is A mg / cm³. 2 The thickness of the elastic coating (2) is d μm, the Vickers hardness of the current collector (12) is k HV, and the particle size of the active particles in the active material layer (13) is D. v50 μm, satisfying 0.01≤k / (A×d×D) v50 ≤30.

07.

2. The battery according to claim 1, characterized in that, The areal density A mg / cm³ of the elastic coating (2) 2 Meets 0.05 mg / cm 2 ≤A mg / cm 2 ≤14 mg / cm 2 ; and / or, The thickness d μm of the elastic coating (2) satisfies 5μm≤d μm≤80μm.

3. The battery according to claim 1, characterized in that, Along the length direction of the electrode (1), the width of the elastic coating (2) is b mm, satisfying 10 mm ≤ b mm ≤ 35 mm.

4. The battery according to claim 1, characterized in that, The electrode (1) has a winding start end (14), and the electrode (1) extends along its width direction to form a first electrode tab (3). The first electrode tab (3) is disposed near the winding start end (14), and the side of the first electrode tab (3) near the winding start end (14) is a first side edge (31). At least one elastic coating (2) is disposed between the winding start end (14) and the first side edge (31).

5. The battery according to claim 4, characterized in that, Along the length direction of the electrode (1), the distance between the first side (31) and the edge of the elastic coating (2) is c1 mm, which satisfies 15 mm ≤ c1 mm ≤ 250 mm.

6. The battery according to claim 5, characterized in that, The distance c1 mm between the first side (31) and the edge of the elastic coating (2) and the width b mm of the elastic coating (2) satisfy c1 mm ≤ 200 mm and 15 mm ≤ b mm ≤ 35 mm.

7. The battery according to claim 1, characterized in that, The electrode (1) has a winding start end (14), and the electrode (1) extends along its width direction to form a first electrode tab (3). The first electrode tab (3) is disposed close to the winding start end (14), and the side of the first electrode tab (3) away from the winding start end (14) is a second side (32). The elastic coating (2) closest to the winding start end (14) is located on the side of the second side (32) away from the winding start end (14).

8. The battery according to claim 7, characterized in that, Along the length direction of the electrode (1), the distance between the second side (32) and the edge of the elastic coating (2) is c2 mm, satisfying 15 mm ≤ c2 mm ≤ 225 mm.

9. The battery according to claim 1, characterized in that, Along the width direction of the electrode (1), the end of the elastic coating (2) does not extend beyond the edge of the active material layer (13), and the distance between the end of the elastic coating (2) and the edge of the active material layer (13) is e mm, satisfying 1 mm ≤ e mm ≤ 15 mm.

10. The battery according to claim 1, characterized in that, Along the width direction of the electrode (1), the end of the elastic coating (2) extends beyond the edge of the active material layer (13) by a width of m mm, and the edge of the current collector (12) extends beyond the edge of the active material layer (13) by a width of n mm, satisfying m≤n.

11. The battery according to claim 10, characterized in that, The width m mm of the end of the elastic coating (2) extending beyond the edge of the active material layer (13) and the width n mm of the edge of the current collector (12) extending beyond the edge of the active material layer (13) satisfy 0.01≤m / n≤1.

12. The battery according to claim 10, characterized in that, The width m mm of the end of the elastic coating (2) extending beyond the edge of the active material layer (13) satisfies 0.1 mm ≤ m mm ≤ 2.6 mm; and / or, The width n mm of the edge of the current collector (12) extending beyond the edge of the active material layer (13) satisfies 1 mm ≤ n mm ≤ 10 mm.

13. The battery according to any one of claims 1 to 12, characterized in that, The electrode (1) is provided with the elastic coating (2) on both opposite sides, and the value of k HV satisfies 30HV≤k HV≤65HV.

14. The battery according to any one of claims 1 to 12, characterized in that, The electrode (1) has a first bending section (15) and a second bending section (16) arranged at relative intervals, and both the first bending section (15) and the second bending section (16) are provided with the elastic coating (2).

15. The battery according to any one of claims 1 to 12, characterized in that, The electrode (1) has a winding start end (14), and the elastic coating (2) is provided on the first bending segment (11) closest to the winding start end (14).

16. The battery according to any one of claims 1 to 12, characterized in that, The electrode (1) is wound in several turns, and the elastic coating (2) is provided within five turns near the starting end (14) of the winding of the electrode (1).

17. The battery according to any one of claims 1 to 12, characterized in that, The electrode (1) is wound in several turns, and a crease (111) is formed at the bending section (11) of the first turn near the starting end (14) of the winding of the electrode (1), and the elastic coating (2) covers the crease (111).

18. The battery according to claim 17, characterized in that, Along the length direction of the electrode (1), the edge of the elastic coating (2) extends beyond the crease (111) by a distance of h mm, satisfying h mm ≥ 3 mm.

19. The battery according to any one of claims 1 to 12, characterized in that, Along the length direction of the electrode (1), there are several elastic coatings (2) spaced apart, and the distance between adjacent elastic coatings (2) is f mm, which satisfies 110 mm ≤ f mm ≤ 300 mm.

20. The battery according to any one of claims 1 to 12, characterized in that, The core (10) has two arc regions (110) arranged at relative intervals and a straight region (120) connected between the two arc regions (110). Along the extension direction of the straight region (120), the width of the core (10) is L mm. Along the length direction of the electrode (1), the width of the elastic coating (2) is b mm, satisfying 0.025≤b / L≤0.

25.

21. The battery according to any one of claims 1 to 12, characterized in that, The particle size D of the active particles in the active material layer (13) v50 μm satisfies 0.2μm≤D v50 μm≤30μm.

22. The battery according to claim 21, characterized in that, The elastic coating (2) is disposed on the positive electrode sheet, D v50 The value of μm satisfies 0.2μm≤D v50 μm≤20μm.

23. The battery according to any one of claims 1 to 12, characterized in that, The current collector (12) has an active material layer (13) on both opposite sides.

24. The battery according to claim 23, characterized in that, The active material layers (13) located on opposite sides of the current collector (12) are a first active material layer (17) and a second active material layer (18), respectively. The particle size of the active particles in the first active material layer (17) is D. v50-1 μm, the particle size of the active particles in the second active material layer (18) is D v50-2 μm, satisfying 3≤|D v50-1 -D v50-2 |≤28.

8.

25. The battery according to any one of claims 1 to 12, characterized in that, Along the length direction of the electrode (1), the electrode (1) also forms a straight section (19) connected to the bent section (11), and the elastic coating (2) extends to the straight section (19).

26. The battery according to claim 25, characterized in that, Along the length direction of the electrode (1), the width of the elastic coating (2) extending onto the straight section (19) is g mm, satisfying g mm ≤ 16 mm.

27. The battery according to any one of claims 1 to 12, characterized in that, The Vickers hardness k HV of the current collector (12) satisfies 30HV≤k HV≤70HV.

28. The battery according to any one of claims 1 to 12, characterized in that, The battery also includes a housing assembly (20) and an electrolyte. The core (10) and the electrolyte are both disposed within the housing assembly (20). The ionic conductivity of the electrolyte ranges from 0.8 mS / cm to 20 mS / cm.

29. The battery according to claim 28, characterized in that, The electrolyte contains at least one of the following: fluoroethylene carbonate, vinylene carbonate, ethylene sulfate, ethylene disulfate, ethylene sulfite, propylene sulfite, and lithium difluorooxalate borate.

30. The battery according to claim 1, characterized in that, The areal density of the elastic coating (2) is A mg / cm³. 2 The thickness of the elastic coating (2) is d μm, the Vickers hardness of the current collector (12) is k HV, and the particle size of the active particles in the active material layer (13) is D. v50 μm satisfies 0.05≤k / (A×d×D) v50 ≤15.

66.

31. A battery device, characterized in that, include: Battery box; The battery according to any one of claims 1 to 30, wherein the battery is disposed within the battery case.

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