Roll core and battery

Abstract

The utility model provides a roll core which comprises a positive plate, a diaphragm and a negative plate, and the positive plate, the diaphragm and the negative plate are sequentially overlapped and then are wound along the direction from a starting end to an ending end to form the roll core; the positive plate comprises a positive current collector and positive active material layers, the positive active material layers are arranged on the surfaces of the two sides of the positive current collector, the positive active material layers located on the two sides of the positive current collector extend to the end part of the ending end of the positive plate, and the thickness of the positive current collector is 0.007-0.012 mm; the compaction density of the single-side positive electrode active material layer is 4.25-4.35 g / cm < 3 >; according to the utility model, the two sides of the positive plate adopt a continuous coating mode, and the step-free design avoids the condition that the stress in a rolling process is concentrated in a certain area, so that the risk that the positive plate is broken is avoided, and meanwhile, a roll core with high energy density can be obtained.

Description

TECHNICAL FIELD

[0001] The utility model relates to a battery technical field, concretely relates to a winding core and battery. BACKGROUND

[0002] The high energy density battery can provide higher energy output without increasing its size or weight, and is currently widely used in electric vehicles, unmanned aerial vehicles, smart phones and other devices that require high power and long endurance.

[0003] The positive plate and the negative plate of the high energy density battery usually use thin current collectors, such as copper foil and aluminum foil, and have high compaction density (such as compaction density ≥ 4.25 g / cm 3 The thin current collector and high compaction density of the pole piece of the high energy density battery will cause certain physical damage to the mechanical strength of the current collector and reduce the tensile strength of the current collector.

[0004] As shown in Figure 1 , in the prior art, the positive plate uses aluminum foil as the positive current collector, and the negative plate uses copper foil as the positive current collector. During winding, the aluminum foil is used as the outermost layer, and one side of the end of the positive plate is a blank foil area.

[0005] Because the strength of the copper foil (≥ 300 N / mm 2 ) is much higher than the strength of the aluminum foil (≥ 190 N / mm 2 ), the aluminum foil is used as the outermost layer, and the electrode expands to squeeze the outermost layer. Because of the fixing effect of the adhesive paper, the stress of the inner electrode during the cycle process will continuously pull the aluminum foil of the outer layer and cause cracking; the thinnest part of the outer aluminum layer is the single-double surface junction area of the aluminum foil, and the single-double surface junction area has a step that is easy to over-press and cause a stress concentration area, which causes the aluminum foil to expand continuously and easily produce micro-cracks; the cracking or micro-cracks of the aluminum foil may cause poor consistency of the battery cycle capacity retention rate, battery cracking, abnormal capacity decay, voltage difference between multiple battery strings, and other abnormal conditions such as inability to fully charge.

[0006] In order to prevent this situation from happening, thick current collectors and reduced compaction density designs are usually selected, but these measures will affect the energy density of the battery. Therefore, how to overcome the above technical problems and defects becomes a key problem to be solved. INVENTION CONTENTS

[0007] In view of the problem that the existing positive plate is prone to cracking or micro-cracks during use, the utility model provides a winding core and battery.

[0008] The technical solution adopted by the utility model to solve the above technical problems is as follows:

[0009] The utility model discloses a kind of roll core, including positive plate, diaphragm and negative plate, the positive plate, the diaphragm and the negative plate are sequentially stacked after the direction of starting end to end of roll winding and form the roll core of the positive plate, the diaphragm and the negative plate;

[0010] The positive plate includes a positive current collector and a positive active material layer, the positive active material layer is arranged on both sides of the positive current collector, and the positive active material layer on both sides of the positive current collector extends to the end of the end of the positive plate.

[0011] The thickness of the positive current collector is 0.007-0.012mm; the compaction density of the positive active material layer on one side is 4.25-4.35g / cm 3 .

[0012] Optionally, the positive current collector is an aluminum foil; the positive active material layers on both sides of the positive current collector are projected on the thickness direction of the positive plate.

[0013] Optionally, the cross section of the roll core is a runway-like structure, the roll core includes a flat area in the middle and a circular arc part on both sides, and the end of the positive plate is located in the flat area of the roll core.

[0014] Optionally, the negative plate includes a negative current collector and a negative active material layer, the negative active material layer is coated on both sides of the negative current collector, the thickness of the negative current collector is 0.004-0.009mm; the compaction density of the negative active material layer on one side is 1.7-1.85g / cm 3 , and the negative current collector is a copper foil.

[0015] Optionally, one side of the starting end of the negative current collector is provided with the negative active material layer, and the other side is provided with an empty foil area without the negative active material layer; the negative active material layers on both sides of the negative current collector both extend to the end of the end of the negative plate.

[0016] Optionally, the starting ends of the negative active material layers on both sides of the negative current collector are aligned in the thickness direction of the negative plate, the starting end of the negative current collector is located in the flat area of the roll core; the starting end of the negative current collector and the starting end of the negative active material layer are located in the same flat area of the roll core.

[0017] Optionally, one side of the end of the negative current collector is provided with the negative active material layer, and the other side is provided with an empty foil area without the negative active material layer; the empty foil area is wound around the outer periphery of the outermost circle of the positive plate and is wound at least one turn; the empty foil area is arranged on the side of the negative current collector away from the positive plate.

[0018] Optionally, the starting end of the empty foil area is located at the junction of the flat area and the circular arc part of the winding core, and the ending end of the empty foil area is located at the flat area of the winding core.

[0019] Optionally, the positive electrode tab and the negative electrode tab are further included, the middle part of the positive electrode sheet is provided with the positive electrode tab, the middle part of the negative electrode sheet is provided with the negative electrode tab, and the projection of the positive electrode tab and the projection of the negative electrode tab do not overlap in the thickness direction of the winding core.

[0020] The utility model discloses a battery on the other side, including battery shell and the winding core as described above, the winding core sets up in the shell.

[0021] According to the winding core provided by the utility model, the positive active material layer is continuously coated on the two side surfaces of the positive current collector, and there is no empty foil area on the two sides of the two ends of the positive current collector, the positive electrode sheet of the utility model cancels the design that the first ending end of the positive current collector is single-sided empty foil area in the past, and the positive electrode sheet adopts the continuous coating mode on the two sides, and the stepless design avoids the stress concentration in a certain area in the rolling process, avoids the risk that the positive electrode sheet is broken, and high-energy-density winding core can be obtained. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical scheme of the embodiment of the utility model, the drawings needed to be used in the description of the embodiment of the utility model will be briefly introduced below, and obviously, the drawings in the following description are only some embodiments of the utility model, and other drawings can be obtained according to these drawings without the creative labor of the ordinary skilled in the art.

[0023] Figure 1 It is the structure schematic diagram of the winding core in the prior high-density battery;

[0024] Figure 2 It is the structure schematic diagram of the winding core provided by an embodiment of the utility model;

[0025] Figure 3 It is the structure schematic diagram of the winding core provided by another embodiment of the utility model;

[0026] Figure 4 It is the front view schematic diagram of the positive electrode sheet provided by an embodiment of the utility model;

[0027] Figure 5 It is the top view schematic diagram of the positive electrode sheet provided by an embodiment of the utility model;

[0028] Figure 6 It is the front view schematic diagram of the negative electrode sheet provided by an embodiment of the utility model;

[0029] Figure 7is a top view schematic diagram of the negative plate provided by an embodiment of the utility model;

[0030] The reference signs in the drawings of the specification are as follows:

[0031] The core; 1-positive plate; 11-positive current collector; 12-positive active material layer; 13-positive lug; 2-negative plate; 21-negative current collector; 22-negative active material; 23-fool area; 231-starting end; 232-end; 24-negative lug; 3-diaphragm; 4-glue paper; 101-straight area; 102-circular arc part. DETAILED DESCRIPTION

[0032] In order to make the technical problems, technical schemes and beneficial effects solved by the utility model more clearly understood, the utility model is further described in detail below in combination with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the utility model and not used to limit the utility model.

[0033] In the description of the utility model, it should be understood that the orientation or position relationship indicated by the terms "longitudinal", "radial", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like is the orientation or position relationship based on the orientation or position relationship shown in the drawings, and is only for the convenience of describing the utility model and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the utility model. In the description of the utility model, unless otherwise specified, the meaning of "a plurality of" is two or more.

[0034] In the description of the utility model, it should be noted that, unless otherwise specified and limited, the terms "mounting", "connection", "connection" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication inside two elements. For ordinary skilled in the art, the specific meaning of the above terms in the utility model can be understood according to the specific circumstances.

[0035] As Figures 2-5 As shown in the figure, in an embodiment, the utility model provides a kind of core in one aspect, including positive plate 1, diaphragm 3 and negative plate 2, positive plate 1, diaphragm 3 and negative plate 2 are sequentially overlapped and are rolled in the direction from starting end to end to form the core 100 described above;

[0036] The positive electrode sheet 1 comprises a positive electrode current collector 11 and a positive electrode active material layer 12, the positive electrode active material layer 12 is arranged on the two side surfaces of the positive electrode current collector 11, and the positive electrode active material layers 12 on the two sides of the positive electrode current collector 11 both extend to the end of the end of the positive electrode sheet 1;

[0037] The thickness of the positive electrode current collector 11 is 0.007-0.012mm; the compaction density of the single-sided positive electrode active material layer 12 is 4.25-4.35g / cm 3 .

[0038] Specifically, the thickness of the positive electrode current collector 11 is any one value or a range value formed by any two point values in 0.007mm, 0.008mm, 0.009mm, 0.010mm, 0.011mm and 0.012mm; in a preferred embodiment, the thickness of the positive electrode current collector 11 is 0.007-0.008mm.

[0039] Specifically, the compaction density of the single-sided positive electrode active material layer 12 is any one value or a range value formed by any two point values in 4.25g / cm 3 , 4.26g / cm 3 , 4.27g / cm 3 , 4.28g / cm 3 , 4.29g / cm 3 , 4.3g / cm 3 , 4.31g / cm 3 , 4.32g / cm 3 , 4.33g / cm 3 , 4.34g / cm 3 , 4.35g / cm 3 ; in a preferred embodiment, the compaction density of the single-sided positive electrode active material layer 12 is 4.25-4.3g / cm 3 .

[0040] The thickness of the positive electrode current collector 11 is 0.007-0.012mm; the compaction density of the single-sided positive electrode active material layer 12 is 4.25-4.35g / cm 3 , the positive electrode sheet 1 of the utility model adopts thinner positive electrode current collector 11 and the positive electrode active material layer 12 with higher compaction density, and is mainly applied to high-energy-density batteries.

[0041] The positive active material layer 12 of the utility model is continuously coated on the two side surfaces of the positive current collector 11, and there is no empty foil area 23 on the two sides of the two ends of the positive current collector 11, the positive plate 1 of the utility model cancels the design that the first end of the positive current collector 11 is empty foil area 23 on one side, the positive plate 1 is continuously coated on both sides, and the design without steps avoids the situation that stress is concentrated in a certain area in the rolling process, avoids the risk that the positive plate 1 is broken, and meanwhile, the high-energy-density roll core can be obtained.

[0042] As shown in the figure, Figures 2-5 In an embodiment, the positive current collector 11 is an aluminum foil; the projections of the positive active material layers 12 on the two sides of the positive current collector 11 in the thickness direction of the positive plate 1 are coincident.

[0043] Specifically, the positive current collector 11 can further include one or more of a copper foil, a nickel foil, a tin foil, a copper foil, and a stainless steel foil in addition to the aluminum foil, and in a more preferred embodiment, the positive current collector 11 is selected from an aluminum foil. The positive active material layer 12 of the utility model is continuously coated on the two side surfaces of the positive current collector 11, and there is no empty foil area 23 on the two sides of the two ends of the positive current collector 11, the positive plate 1 of the utility model cancels the design that the first end of the positive current collector 11 is empty foil area 23 on one side, the positive plate 1 is continuously coated on both sides, and the design without steps avoids the situation that stress is concentrated in a certain area in the rolling process, avoids the risk that the positive plate 1 is broken, and meanwhile, the high-energy-density roll core can be obtained.

[0044] As shown in the figure, Figures 2-3 In an embodiment, the cross section of the roll core 100 is a runway-like structure, the roll core 100 includes a flat area 101 in the middle and a circular arc part 102 on both sides, and the end of the positive plate 1 is located in the flat area 101 of the roll core 100.

[0045] Specifically, the end of the positive plate 1 is located in the flat area 101 of the roll core 100, compared with the end of the positive plate 1 being located in the circular arc part 102 of the roll core 100, the end of the positive plate 1 is not easily pulled by the expansion of the circular arc part 102 in the battery cycle process, and the stress concentration of the end of the positive plate 1 is reduced; the surface of the end of the positive plate 1 is not easy to produce micro cracks, thereby reducing the risk of breaking of the positive plate 1.

[0046] As shown in the figure, Figures 2-3 And Figures 6-7 As shown in the figure, In an embodiment, the negative plate 2 includes a negative current collector 21 and a negative active material 22 layer, the negative active material 22 layer is coated on the two side surfaces of the negative current collector 21, the thickness of the negative current collector 21 is 0.004-0.009 mm; the compaction density of the negative active material 22 layer on one side is 1.7-1.85 g / cm 3 The negative current collector 21 is a copper foil.

[0047] Specifically, the thickness of the negative current collector 21 is any one value or a range value formed by any two point values in 0.004 mm, 0.005 mm, 0.006 mm, 0.007 mm, 0.008 mm or 0.009 mm; in a preferred embodiment, the thickness of the negative current collector 21 is 0.004-0.005 mm.

[0048] Specifically, the compaction density of the single-sided negative active material 22 layer is any one value or a range value formed by any two point values in 1.7 g / cm 3 , 1.71 g / cm 3 , 1.72 g / cm 3 , 1.73 g / cm 3 , 1.74 g / cm 3 , 1.75 g / cm 3 , 1.76 g / cm 3 , 1.77 g / cm 3 , 1.78 g / cm 3 , 1.79 g / cm 3 , 1.8 g / cm 3 , 1.81 g / cm 3 , 1.82 g / cm 3 , 1.83 g / cm 3 , 1.84 g / cm 3 or 1.85 g / cm 3 ; in a preferred embodiment, the compaction density of the single-sided negative active material 22 layer is 1.75-1.80 g / cm 3 .

[0049] The thickness of the negative current collector 21 of the utility model is 0.004-0.009 mm; the compaction density of the single-sided negative active material 22 layer is 1.7-1.85 g / cm 3 , the negative plate 2 of the utility model is composed of thin negative current collector 21 and negative active material 22 layer with high compaction density, and is mainly applied to high-energy-density batteries.

[0050] The negative current collector 21 is selected from metal materials that can conduct electrons, specifically, the negative current collector 21 includes one or more of aluminum foil, nickel foil, tin foil, copper foil and stainless steel foil, and in a more preferred embodiment, the negative current collector 21 is selected from copper foil.

[0051] As shown in Figure 1 and Figures 6-7 , in an embodiment, one side of the starting end of the negative current collector 21 is provided with a negative active material layer 22, and the other side is provided with an empty foil area 23 without the negative active material layer 22, and the negative active material layers 22 on both sides of the negative current collector 21 are extended to the end of the end of the negative plate 1.

[0052] As shown in Figure 2 and Figures 6-7 , in an embodiment, the starting end of the negative active material layer 22 on both sides of the negative current collector 21 is aligned in the thickness direction of the negative plate, and the starting end of the negative current collector 21 is located in the flat area 101 of the winding core 100, and the starting end of the negative current collector 21 and the starting end of the negative active material layer 22 are located in the same flat area 101 of the winding core 100.

[0053] In an embodiment, the starting end of the negative active material layer 22 on both sides of the negative current collector 21 coincides with the starting end of the negative current collector 21, and there is no empty foil area 23 on both sides of the starting end of the negative current collector 21 of the utility model;

[0054] In another embodiment, the starting end of the negative active material layer 22 on both sides of the negative current collector 21 is close to the starting end of the negative current collector 21.

[0055] In the prior art, at least one side of the starting end of the negative current collector 21 has an empty foil area, and the single-sided area of the starting end of the negative plate 2 is prone to folding when winding into a winding core 100; compared with the prior art, the starting end of the negative active material layer 22 on both sides of the negative current collector 21 is aligned in the thickness direction of the negative plate, and the starting end of the negative plate 2 is located in the flat area 101 of the winding core 100, and the starting end of the negative current collector 21 and the starting end of the negative active material layer 22 are located in the same flat area 101 of the winding core 100, the negative plate 2 of the application is not easy to bend when winding, and the inner circle of the winding core 100 is more convenient to wind tightly, thereby improving the energy density of the battery.

[0056] As shown in Figure 3 and Figures 6-7 , in an embodiment, one side of the ending end of the negative current collector 21 is provided with a negative active material layer 22, and the other side is provided with an empty foil area 23 without coating the negative active material layer 22, and the empty foil area 23 is wound around the outer periphery of the outermost circle of the positive plate 1 and wound at least one circle; the empty foil area 23 is arranged on the side of the negative current collector 21 away from the positive plate 1.

[0057] In the prior art, there is no empty foil area 23 on both sides of the ending end of the negative current collector 21, and the ending end of the negative plate 2 is prone to folding when winding into a winding core 100; in the utility model, one side of the ending end of the negative current collector 21 is provided with an empty foil area 23, and the empty foil area 23 is not coated with a negative active material layer 22, compared with the prior art, the ending end of the negative plate 2 is relatively loose when winding and is not easy to fold.

[0058] When there is mechanical abuse, the outer negative current collector 21 can act as a buffer, which has the technical effects of improving product energy density and improving product safety.

[0059] As shown in Figure 2 and Figures 6-7 In an embodiment, the starting end 231 of the empty foil area 23 of the negative electrode sheet 2 is located at the junction of the flat area 101 and the circular arc part 102 of the winding core 100, and the ending end 232 of the empty foil area 23 is located at the flat area 101 of the winding core 100.

[0060] The starting end 231 of the empty foil area 23 of the utility model is located at the junction of the flat area 101 and the circular arc part 102 of the winding core 100, thereby having the technical effect that the winding core thickness is flat and consistent without obvious thickness steps; when the ending end 232 of the empty foil area 23 is located at the flat area 101 of the winding core 100, the technical effect that the ending is flat and the battery appearance is smooth is achieved.

[0061] As shown in Figures 2-3 and Figures 6-7 In an embodiment, the positive electrode tab 13 and the negative electrode tab 24 are further included, the middle part of the positive electrode sheet 1 is provided with the positive electrode tab 13, the middle part of the negative electrode sheet 2 is provided with the negative electrode tab 24, and the projection of the positive electrode tab 13 and the projection of the negative electrode tab 24 do not overlap in the thickness direction of the winding core 100.

[0062] Specifically, the middle part of the positive electrode sheet 1 is provided with an uncoated area on both sides, the positive electrode tab 13 is welded on the uncoated area, and the outer side of the uncoated area is adhered with the adhesive tape 4, the adhesive tape 4 is used for fixing the positive electrode tab 13, and the positive electrode tab 13 is close to the inner circle of the winding core 100.

[0063] The middle part of the negative electrode sheet 2 is also provided with an uncoated area on both sides, the negative electrode tab 24 is welded on the uncoated area, and the outer side of the uncoated area is adhered with the adhesive tape 4, the adhesive tape 4 is used for fixing the negative electrode tab 24, and the negative electrode tab 24 is close to the outer circle of the winding core 100, the positive electrode tab 13 and the negative electrode tab 24 are staggered, thereby facilitating the connection of the positive electrode tab 13 and the positive electrode column and the connection of the negative electrode tab 24 and the negative electrode column.

[0064] In an embodiment, the utility model further provides a battery, which comprises a battery shell and the winding core 100 as described above, and the winding core 100 is arranged in the shell.

[0065] Specifically, the application further comprises an electrolyte, the winding core 100 is arranged in the shell, and the battery of the application is formed by liquid injection and packaging.

[0066] The battery provided by the embodiment of the utility model comprises the winding core provided by the foregoing embodiment, and the winding core has the advantages of high energy density as described in the foregoing embodiment, so that the battery provided by the embodiment of the application also has the advantages of high energy density as described in the foregoing embodiment.

[0067] The above merely describes preferred embodiments of the present application and is not intended to limit the present application, and any modification, equivalent replacement, and improvement within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A core, characterized by: The core comprises a positive electrode sheet, a separator and a negative electrode sheet, which are sequentially stacked and wound in a direction from a starting end to an ending end to form the core; The positive electrode sheet comprises a positive electrode current collector and positive electrode active material layers arranged on both sides of the positive electrode current collector; the positive electrode active material layers on both sides of the positive electrode current collector extend to the end of the ending end of the positive electrode sheet. The thickness of the positive electrode current collector is 0.007-0.012 mm; the compaction density of the single-sided positive electrode active material layer is 4.25-4.35 g / cm 3 .

2. The core of claim 1, wherein: The positive electrode current collector is an aluminum foil; the projections of the positive electrode active material layers on both sides of the positive electrode current collector in the thickness direction of the positive electrode sheet coincide.

3. The core of claim 1, wherein: The cross section of the core is a structure similar to a racetrack, the core comprises a flat area in the middle and circular arc portions on both sides, and the ending end of the positive electrode sheet is located in the flat area of the core.

4. The core of claim 3, wherein: The negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer coated on both side surfaces of the negative electrode current collector, the negative electrode current collector has a thickness of 0.004-0.009 mm, and the compaction density of the negative electrode active material layer on one side is 1.7-1.85 g / cm 3 , and the negative electrode current collector is a copper foil.

5. The core of claim 4, wherein: The negative electrode current collector is provided with the negative electrode active material layer on one side of the starting end and an empty foil area without the negative electrode active material layer on the other side; the negative electrode active material layers on both sides of the negative electrode current collector extend to the end of the ending end of the negative electrode sheet.

6. The core of claim 5, wherein: The starting ends of the negative electrode active material layers on both sides of the negative electrode current collector are aligned in the thickness direction of the negative electrode sheet, and the starting end of the negative electrode current collector is located in the flat area of the core; the starting end of the negative electrode current collector and the starting end of the negative electrode active material layer are located in the same flat area of the core.

7. The core of claim 6, wherein: The negative electrode current collector is provided with the negative electrode active material layer on one side of the ending end and an empty foil area without the negative electrode active material layer on the other side; the empty foil area is wound around the outer periphery of the outermost circle of the positive electrode sheet by at least one turn; and the empty foil area is arranged on the side of the negative electrode current collector away from the positive electrode sheet.

8. The core of claim 6, wherein: The starting end of the empty foil area is located at the junction of the flat area and the circular arc portion of the core, and the ending end of the empty foil area is located in the flat area of the core.

9. The core of claim 1, wherein: The core further comprises a positive electrode lug and a negative electrode lug, the middle of the positive electrode sheet is provided with the positive electrode lug, and the middle of the negative electrode sheet is provided with the negative electrode lug; the projection of the positive electrode lug and the projection of the negative electrode lug do not overlap in the thickness direction of the core.

10. A battery, characterized by: The battery shell and the core as claimed in any one of claims 1-9 are provided in the shell.

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