Battery

Abstract

The utility model relates to the technical field of batteries, and discloses a battery which comprises a packaging film provided with a first accommodating cavity, a first bottom wall of the first accommodating cavity comprises a first area, and the thickness D1 of a heat sealing layer of the first area is smaller than the thickness D of a heat sealing layer of a first side wall; the battery cell comprises a positive plate, a diaphragm and a negative plate, the distance between the edge of the negative plate and the edge of the positive plate on the same side is a first distance L1, and a first edge close to the edge of the positive plate is arranged in a first region in the second direction; at least part of the first insulating part is located between the first edge and the edge of the positive plate in the second direction, the first insulating part is provided with a first edge close to the edge of the positive plate, a second distance L2 exists between the first edge and the edge of the positive plate, and the second distance L2 is smaller than the first distance L1. The first insulating part separates the metal layer in the first area from the negative plate or the negative tab, so that the risks of short circuit and electrochemical corrosion of the battery are reduced, and the safety performance of the battery is improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to battery technology field, concretely relates to battery. BACKGROUND

[0002] Soft package lithium ion battery has the advantages of high energy density, high output power and high cycle life. In recent years, with the continuous development of consumer electronics industry, higher requirements are put forward for the energy density of the battery. The shell of the soft package lithium ion battery usually uses a thin and soft packaging film. The packaging film is a composite material, which is usually composed of a heat-sealing layer, a metal layer and a protective layer. The metal layer is generally an aluminum layer and its aluminum compound. The heat-sealing layer ensures the sealing performance of the packaging film, the metal layer ensures the water vapor barrier performance of the packaging film, and the protective layer protects the metal layer from being pierced.

[0003] To improve the energy density of the battery, some lithium battery manufacturers try to use thinner packaging films for packaging. However, the overall thickness of the packaging film is reduced, and its resistance to internal expansion stress of the battery will correspondingly decrease, and the packaging film is prone to rupture during the battery drop test. Therefore, the current battery has the problem that the energy density and safety performance cannot be balanced. SUMMARY

[0004] Therefore, the utility model provides a kind of battery to solve the problem that the safety performance and energy density of battery cannot be balanced after packaging film is thinned.

[0005] The utility model provides a kind of battery, comprising: packaging film, including along the first direction from outside to inside layer arrangement protective layer, metal layer and heat-sealing layer, packaging film has first accommodating cavity, first accommodating cavity includes first bottom wall and the first side wall around first bottom wall, and first bottom wall and first side wall are enclosed to form first accommodating cavity, and first bottom wall includes first area, and the thickness D1 of heat-sealing layer of first area is less than the thickness D of heat-sealing layer of first side wall;Battery cell is set in first accommodating cavity, and battery cell includes the positive plate, diaphragm and negative plate of layer arrangement, along the first direction, the heat-sealing layer of first bottom wall is set to battery cell, along the second direction, the edge of negative plate exceeds the edge of positive plate, and the distance between the edge of negative plate and the edge of positive plate on the same side of second direction is first distance L1, along the second direction, first area has the first edge close to the edge of positive plate;First insulating part, at least part first insulating part is between first edge and the edge of positive plate along the second direction, along the second direction, first insulating part has the first side close to the edge of positive plate, and the second distance L2 between first side and the edge of positive plate is less than first distance L1.

[0006] In an optional embodiment, the first distance L1 and the second distance L2 satisfy: 0≤L2 / L1≤2 / 3; and / or, the first distance L1 satisfies: 0.2mm≤L1≤2mm; and / or, the second distance L2 satisfies: 0≤L2≤1.35mm.

[0007] In an optional embodiment, along the same side of the second direction, the first insulating piece has a second edge away from the edge of the positive electrode sheet, and the distance between the second edge and the edge of the diaphragm is a third distance L3; along the second direction, the edge of the diaphragm exceeds the edge of the negative electrode sheet, and the distance between the edge of the diaphragm and the edge of the negative electrode sheet on the same side of the second direction is a fourth distance L4; the third distance L3 and the fourth distance L4 satisfy: L3=L4.

[0008] In an optional embodiment, along the third direction, the width W1 of the first insulating piece is greater than or equal to the width W of the first area.

[0009] In an optional embodiment, the battery cell has a flat area and a circular arc area arranged on both sides of the flat area in the third direction, and along the third direction, the width W of the first area is greater than the width W3 of the flat area; and / or, on the same side of the second direction, the first edge is located between the edge of the positive electrode sheet and the edge of the negative electrode sheet.

[0010] In an optional embodiment, the battery cell is provided with a first adhesive layer on the side facing the first bottom wall, and along the first direction, the thickness T1 of the first insulating piece is less than the thickness T2 of the first adhesive layer.

[0011] In an optional embodiment, the first insulating piece is arranged on at least one of the battery cell and the packaging film.

[0012] In an optional embodiment, the intersection of the first bottom wall and the first side wall forms a transition area, the distance between the edge of the first area and the edge of the transition area on the same side of the second direction is a fifth distance L5, the fifth distance L5 is 0-10mm, the distance between the edge of the first area and the edge of the transition area on the same side of the third direction is a sixth distance L6, the sixth distance L6 is 0-10mm; and / or, the distance between the first edge and the edge of the negative electrode sheet is a seventh distance L, the seventh distance L is 0.1mm-1.5mm; and / or, the thickness D1 of the heat-seal layer of the first area is 0-20μm; and / or, the thickness D of the heat-seal layer of the first side wall is 20μm-50μm.

[0013] In an alternative embodiment, the packaging film comprises a first body and a second body oppositely arranged along a first direction, the first body has a first accommodating cavity, and the second body comprises a second region, a thickness of a heat-seal layer of the second region is less than a thickness D of the heat-seal layer of the first side wall; along a second direction, the first body and the second body have a sealing area between one side of the first accommodating cavity, and a distance D3 between the second region and the sealing area along the second direction is 0.3mm-2.4mm.

[0014] In an alternative embodiment, along the second direction, the second region has a second edge close to an edge of the positive electrode sheet; the second body has a second accommodating cavity, the second accommodating cavity comprises a second bottom wall and a second side wall surrounding the second bottom wall, the second bottom wall and the second side wall enclose the second accommodating cavity, along the first direction, a depth of the second accommodating cavity is less than a depth of the first accommodating cavity, and the second bottom wall has the second region; the battery further comprises a second insulating member, at least part of the second insulating member is located between the second edge and the edge of the positive electrode sheet along the second direction, a thickness of the second insulating member is less than a thickness of the first insulating member, and a difference between the thickness T1 of the first insulating member and the thickness T3 of the second insulating member is 5-8um.

[0015] The technical scheme of the present application has the following advantages:

[0016] The first insulating member is arranged between the battery cell and the packaging film, at least part of the first insulating member is located between the first edge and the edge of the positive electrode sheet along the second direction, and the second distance L is less than the first distance L, so that the first insulating member can cover the metal layer between the edge of the first region and the edge of the positive electrode sheet. On the one hand, when the negative tab is bent out of one end of the battery cell body at a certain angle, it will first contact the first insulating member, which can block the contact between the negative tab and the metal layer of the first region, reducing the risk of direct contact between the negative tab and the metal layer when bending. Or, in the battery drop test, the negative tab will first contact the first insulating member, which can block the contact between the negative tab and the metal layer of the first region, reducing the risk of the negative tab piercing the thin heat-seal layer and contacting the metal layer, thereby solving the problem of battery leakage and abnormal swelling caused by electrochemical corrosion of the contact between the negative tab and the metal layer. On the other hand, during the drop test of the battery cell, the bending of the positive electrode sheet beyond the positive region will first contact the first insulating member, which can block the contact between the bending region of the negative electrode sheet and the metal layer of the first region, reducing the risk of direct contact between the negative electrode sheet and the metal layer of the packaging film, thereby reducing the risk of short circuit caused by the contact between the negative electrode sheet and the metal aluminum layer of the packaging film, and solving the safety problem of fire or explosion caused by the short circuit of the battery cell due to the contact between the negative electrode sheet and the metal layer of the first region during the drop test of the battery cell.

[0017] Therefore, the first area and the first insulating piece can improve the energy density of the battery while avoiding short circuit or swelling, liquid leakage, and thus improving the safety performance and insulation performance of the battery, so that the safety performance and energy density of the battery can be balanced, and the service life of the battery is prolonged.

[0018] By controlling L2 / L1 in the range of 0-2 / 3, the first insulating piece 3 effectively blocks the metal layer 102 of the first area 1043 from the negative tab 203 or the negative pole lug, reduces the risk of contact between the metal layer 102 of the first area 1043 and the negative tab 203 or the negative pole lug, and thus reduces the risk of short circuit and electrochemical corrosion of the battery, improves the safety performance of the battery, and prolongs the service life of the battery.

[0019] Additional aspects and advantages of the embodiments of the present application will be described and shown in part in the following description and drawings, or will be understood and explained by the practice of the embodiments of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the drawings needed in the following specific embodiments or prior art description will be briefly introduced. Obviously, the drawings in the following description are some embodiments of the present application, and those skilled in the art can also obtain other drawings according to these drawings without creative labor.

[0021] Figure 1 A structure schematic view of a battery in a second direction according to the embodiments of the present application is shown in the figure;

[0022] Figure 2 A structure schematic view of a battery in a second direction according to the embodiments of the present application is shown in the figure; Figure 1 A structure schematic view of a battery in a second direction according to the embodiments of the present application is shown in the figure;

[0023] Figure 3 A structure schematic view of a battery in a second direction according to the embodiments of the present application is shown in the figure; Figure 1 A structure schematic view of a battery in a second direction according to the embodiments of the present application is shown in the figure;

[0024] Figure 4 A structure schematic view of a battery in a second direction according to the embodiments of the present application is shown in the figure; Figure 1 A structure schematic view of a battery in a second direction according to the embodiments of the present application is shown in the figure;

[0025] Figure 5 A structure schematic view of a battery in a second direction according to the embodiments of the present application is shown in the figure; Figure 1 A structure schematic view of a battery in a second direction according to the embodiments of the present application is shown in the figure;

[0026] Figure 6 A structure schematic view of a battery in a second direction according to the embodiments of the present application is shown in the figure; Figure 1 A structure schematic view of a battery in a second direction according to the embodiments of the present application is shown in the figure;

[0027] Figure 7 A structure schematic view of a battery in a second direction according to the embodiments of the present application is shown in the figure; Figure 5Structure schematic view of the positive electrode sheet, the negative electrode sheet, the diaphragm and the first insulating piece shown in the figure;

[0028] Figure 8 For Figure 1 Structure schematic view of the packaging film when being unfolded shown in the figure;

[0029] Figure 9 For Figure 8 Partly three-dimensional schematic view of the packaging film shown in the figure;

[0030] Figure 10 For Figure 1 Structure schematic view of the battery in the third direction shown in the figure;

[0031] Figure 11 Structure schematic view of another battery in the second direction of the embodiment of the utility model;

[0032] Figure 12 For Figure 11 Structure schematic view of the battery in the third direction shown in the figure;

[0033] Figure 13 For Figure 11 Top view of the battery shown in the figure;

[0034] Figure 14 For Figure 11 Structure schematic view of the battery cell shown in the figure.

[0035] Explanation of reference signs:

[0036] 1, packaging film; 101, protective layer; 102, metal layer; 103, heat-seal layer; 104, first accommodating cavity; 1041, first bottom wall; 1042, first side wall; 1043, first area; 1045, first edge; 1049, transition area; 106, first body; 107, second body; 1071, second area; 1072, second edge; 108, second accommodating cavity; 1081, second bottom wall; 1082, second side wall; 109, sealing area;

[0037] 2, battery cell; 201, positive electrode sheet; 202, diaphragm; 203, negative electrode sheet; 2031, third edge; 204, flat area; 205, circular arc area; 206, first adhesive layer;

[0038] 3, first insulating piece; 301, first side; 302, second side;

[0039] 6, second insulating piece. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical scheme and advantages of the embodiments of the utility model clearer, the technical scheme of the embodiments of the utility model will be clearly and completely described below in combination with the drawings in the embodiments of the utility model. Obviously, the described embodiments are part of the embodiments of the utility model, rather than all the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by the person skilled in the art without creative labor belong to the protection scope of the utility model.

[0041] The embodiments of the utility model will be described below in combination with Figures 1 to 14

[0042] According to the embodiments of the utility model, on the one hand, a battery is provided, which comprises a packaging film 1, a battery core 2 and a first insulating part 3.

[0043] Specifically, the packaging film 1 comprises a protection layer 101, a metal layer 102 and a heat sealing layer 103 which are stacked from outside to inside along a first direction, and the packaging film 1 has a first accommodating cavity 104 which comprises a first bottom wall 1041 and a first side wall 1042 surrounding the first bottom wall 1041, and the first bottom wall 1041 and the first side wall 1042 enclose the first accommodating cavity 104, and the first bottom wall 1041 comprises a first area 1043, and the thickness D1 of the heat sealing layer 103 of the first area 1043 is less than the thickness D of the heat sealing layer 103 of the first side wall 1042.

[0044] The battery core 2 is arranged in the first accommodating cavity 104, and the battery core 2 comprises a positive electrode sheet 201, a diaphragm 202 and a negative electrode sheet 203 which are stacked, along the first direction, the heat sealing layer 103 of the first bottom wall 1041 faces the battery core 2, along a second direction, the edge of the negative electrode sheet 203 exceeds the edge of the positive electrode sheet 201, and the distance between the edge of the negative electrode sheet 203 and the edge of the positive electrode sheet 201 on the same side of the second direction is a first distance L1, and along the second direction, the first area 1043 has a first edge 1045 close to the edge of the positive electrode sheet 201.

[0045] At least part of the first insulating part 3 is located between the first edge 1045 and the edge of the positive electrode sheet 201 along the second direction, and along the second direction, the first insulating part 3 has a first edge 301 close to the edge of the positive electrode sheet 201, and the first edge 301 and the edge of the positive electrode sheet 201 have a second distance L2 therebetween, and the second distance L2 is less than the first distance L1.

[0046] ​It should be noted that the first distance L1 refers to the distance by which the edge of the negative tab 203 on the same side exceeds the edge of the positive tab 201, the first direction is the thickness direction of the battery cell 2, the second direction is the height direction of the battery cell 2, the inside refers to the side of the packaging film 1 facing the battery cell 2, and the outside refers to the side of the packaging film 1 facing the external environment. Generally, the height of the battery is greater than the width of the battery, and the width of the battery is greater than the thickness of the battery.

[0047] The inventors of the present application found that the heat-seal layer 103 of the inner part of the packaging film 1 can be cleaned. This scheme can improve the energy density of the battery without damaging the heat-sealability, protection performance, and safety performance of the packaging film 1. However, the cleaned packaging film 1 with the heat-seal layer 103 has the following problems: the heat-seal layer 103 of the cleaned packaging film 1 is thinned or exposes the intermediate metal layer 102. On the one hand, the battery cell 2 includes a negative tab, which is bent at an angle from one end of the battery cell 2 body. The negative tab has a risk of directly contacting the metal layer 102, or in the battery drop test, the negative tab is easily pierced through the thinned heat-seal layer 103, thereby causing electrochemical corrosion, and further causing problems such as battery swelling and liquid leakage. On the other hand, in order to ensure safety in the design of the winding core, the size of the negative tab 203 is usually greater than that of the positive tab 201. At this time, in the drop test of the battery cell 2, the negative tab 203 exceeds the area of the positive tab and bends and extrudes the packaging film 1, causing the heat-seal layer 103 of the packaging film 1 to be pierced and directly contact the metal layer 102 of the packaging film 1. When the battery is electrified, the negative tab 203 contacting the metal aluminum layer of the packaging film 1 can cause the battery to short circuit, and even cause the battery to catch fire or explode.

[0048] In order to avoid the short circuit or the conditions of the battery gas, liquid leakage, the first insulating part 3 is arranged between the battery cell 2 and the packaging film 1, at least part of the first insulating part 3 is located between the first edge 1045 and the edge of the positive plate 201 in the second direction, and the second distance L2 is less than the first distance L1, so that the first insulating part 3 can cover the metal layer 102 between the edge of the first area 1043 and the edge of the positive plate 201. On the one hand, when the negative tab is bent at an angle from one end of the battery cell 2 body, it will first contact the first insulating part 3, and the first insulating part can block the negative tab from contacting the metal layer 102 of the first area 1043, which can reduce the risk of direct contact between the negative tab and the metal layer when the negative tab is bent. Or, in the battery drop test, the negative tab will first contact the first insulating part, and the first insulating part can block the negative tab from contacting the metal layer of the first area, reducing the risk of the negative tab piercing the thinned heat-sealed layer 103 and contacting the metal layer of the packaging film 1, thereby solving the problem of battery leakage and abnormal swelling caused by the electrochemical corrosion of the contact between the negative tab and the metal layer 102. On the other hand, in the drop test process of the battery cell, the bending of the negative plate beyond the positive area will first contact the first insulating part, and the first insulating part can block the bending area of the negative plate from contacting the metal layer of the first area, reducing the risk of the negative plate piercing the heat-sealed layer 103 of the packaging film 1 and directly contacting the metal layer of the packaging film 1, thereby reducing the risk of short circuit caused by the contact between the negative plate and the metal aluminum layer of the packaging film, thereby solving the problem of fire or even explosion caused by the short circuit of the battery cell 2 caused by the contact between the negative plate 203 and the metal layer 102 of the first area 1043 during the drop process of the battery cell 2.

[0049] Therefore, the setting of the first area 1043 and the first insulating part 3 can improve the energy density of the battery while avoiding short circuit or gas, liquid leakage, thereby improving the safety performance and insulation performance of the battery, so that the safety performance and energy density of the battery can be considered, and the service life of the battery can be prolonged.

[0050] In one embodiment, the first distance L1 and the second distance L2 satisfy: 0≤L2 / L1≤2 / 3. If the ratio of L2 / L1 is too large, the first edge 301 coincides with or exceeds the edge of the negative plate 203, which cannot play an insulating role and increases the risk of contact between the metal layer 102 of the first area 1043 and the negative plate 203 or the negative tab.

[0051] Therefore, by controlling L2 / L1 in the range of 0-2 / 3, the first insulating part 3 effectively blocks the metal layer 102 of the first area 1043 and the negative plate 203 or the negative tab, reducing the risk of contact between the metal layer 102 of the first area 1043 and the negative plate 203 or the negative tab, thereby reducing the risk of short circuit and electrochemical corrosion of the battery, improving the safety performance of the battery, and prolonging the service life of the battery.

[0052] In one embodiment, the first distance L1 satisfies: 0.2mm≤L1≤2mm. The first distance L1 cannot be too large or too small. If L1 is too large, the distance between the negative electrode sheet 203 and the positive electrode sheet 201 is too large, the size of the negative electrode sheet 203 is large, which causes the size of the battery cell 2 to be large, increases the invalid size of the negative electrode sheet 203, and thus reduces the energy density of the battery. When L1 is too large, in addition to increasing the risk of the battery cell 2 puncturing the packaging film 1 during the drop test, it also increases the risk of the negative electrode being inserted into the battery cell 2 and causing a short circuit.

[0053] Therefore, by controlling L1 to be within the range of 0.2mm-2mm, it can be ensured that the negative electrode sheet 203 completely covers the active material layer of the positive electrode sheet 201, and it can be ensured that all lithium ions on the positive electrode sheet 201 can find corresponding negative electrode materials for intercalation or deintercalation during the charging and discharging process, thereby avoiding the formation of lithium dendrites and capacity loss, which helps to improve the cycle life and charging and discharging efficiency of the battery. At the same time, it can also avoid the size of the negative electrode sheet 203 being too large, and improve the energy density of the battery.

[0054] For example, L1 is 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm, 2mm, or within the range formed by any two of the above values.

[0055] It should be noted that the value of L1 can be different for different types of batteries, and the value of L1 should be selected according to specific needs.

[0056] In one embodiment, the second distance L2 satisfies: 0≤L2≤1.35mm. If L2 is too large, the risk of metal exposure of the first region 1043 is increased, the insulation protection effect is poor, and thus the risk of contact between the negative electrode sheet 203 or the negative electrode tab and the metal layer 102 of the first region 1043 is increased, and the risk of short circuit and electrochemical corrosion of the battery is large. At the same time, it also increases the risk of the battery failing the drop test.

[0057] Therefore, by controlling L2 to be within the range of 0-1.35mm, a good insulation protection effect is ensured, and the risk of contact between the negative electrode sheet 203 or the negative electrode tab and the metal layer 102 at the first region 1043 is effectively reduced.

[0058] Exemplarily, L2 is 0, 0.1, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1 mm, 1.1 mm, 1.2 mm, 1.3 mm, 1.35 mm or within a range between any two of the above values.

[0059] In one embodiment, along the same side of the second direction, the first insulating piece 3 has a second edge 302 away from the edge of the positive plate 201, and the distance between the second edge 302 and the edge of the diaphragm 202 is a third distance L3; along the second direction, the edge of the diaphragm 202 exceeds the edge of the negative plate 203, and the distance between the edge of the diaphragm 202 and the edge of the negative plate 203 on the same side of the second direction is a fourth distance L4; the third distance L3 and the fourth distance L4 satisfy: L3 = (1 / 3-3 / 4)L4.

[0060] Further, L3 / L4 cannot be too large or too small. If L3 / L4 is too small, the projection area of the first insulating piece 3 on the first bottom wall 1041 cannot effectively cover the edge of the projection of the negative plate 203 on the first bottom wall 1041, increasing the risk of contact between the negative plate 203 or the negative tab and the metal layer 102 of the first area 1043, and the risk of short circuit and electrochemical corrosion of the battery. If L3 / L4 is too large, the distance of the first insulating piece 3 beyond the negative plate 203 is large, and the size of the first insulating piece 3 is large, increasing the amount of material and the cost.

[0061] Therefore, by controlling L3 / L4 within the range of 1 / 3-3 / 4, the projection area of the first insulating piece 3 on the first bottom wall 1041 can completely cover the edge of the projection of the negative plate 203 on the first bottom wall 1041, and the insulation protection effect is better. It can be avoided that the metal layer 102 of the first area 1043 contacts the negative plate 203 or the negative tab, thereby reducing the risk of short circuit and electrochemical corrosion of the battery, improving the safety performance of the battery, and prolonging the service life of the battery. At the same time, the size of the first insulating piece 3 is controlled, and the amount of material and cost is reduced.

[0062] Exemplarily, L3 / L4 is 1 / 3, 1 / 2, 3 / 5, 2 / 3, 3 / 4 or within a range between any two of the above values. Preferably, L3 / L4 is 1 / 2, L3 is 0.5 nm, and L4 is 1 nm.

[0063] In one embodiment, the first insulating piece 3 has a width W1 in the third direction that is greater than or equal to the width W of the first region 1043. The provision of W1 greater than or equal to W can ensure that the first insulating piece 3 can comprehensively cover and insulate the battery cell 2, further reduce the risk of short circuit and electrochemical corrosion of the battery, improve the safety performance of the battery, and prolong the service life of the battery.

[0064] It should be noted that the third direction is the width direction of the battery cell 2.

[0065] In one embodiment, the battery cell 2 has a flat region 204 and a circular arc region 205 arranged on both sides of the flat region 204 in the third direction. The width W of the first region 1043 is greater than the width W3 of the flat region 204 in the third direction. By controlling the width W of the first region 1043, the opposite edges of the first region 1043 in the third direction do not coincide with the flat region 204, so that the flat region 204 of the battery cell 2 is located within the first region 1043. Since the thickness D1 of the heat sealing layer 103 of the first region 1043 is less than the thickness D of the heat sealing layer 103 of the first side wall 1042, the thickness of the battery can be effectively reduced, and the space utilization of the battery on the device can be optimized.

[0066] In one embodiment, the first edge 1045 is located between the edge of the positive plate 201 and the edge of the negative plate 203 on the same side in the second direction. The projection of the edge of the negative plate 203 on the first bottom wall 1041 is located outside the first region 1043, further avoiding the edge or the negative tab of the negative plate 203 from contacting the metal layer 102 of the first region 1043. In addition, the thickness of the heat sealing layer 103 on the outside of the first region 1043 is relatively thick, which can also avoid the edge or the negative tab of the negative plate 203 from contacting the metal layer 102 on the outside of the first region 1043, further reducing the risk of electrochemical corrosion or short circuit of the battery.

[0067] In one embodiment, the side of the battery cell 2 facing the first bottom wall 1041 is provided with a first adhesive layer 206. The thickness T1 of the first insulating piece 3 in the first direction is less than the thickness T2 of the first adhesive layer 206. By making T1 less than T2, it can be ensured that the first insulating piece 3 does not affect the thickness of the battery cell 2, effectively avoiding the case that the first insulating piece 3 affects the thickness of the battery cell 2 and reduces the energy density of the battery, thereby ensuring the energy density of the battery.

[0068] In one embodiment, the first insulating piece 3 is arranged on at least one of the battery cell 2 and the packaging film 1. The fixing position of the first insulating piece 3 can be selected according to the manufacturing process, which is more flexible.

[0069] Specifically, the first insulation piece 3 can be arranged on the battery cell 2, or arranged on the packaging film 1, or divided into two parts, one part arranged on the battery cell 2, and the other part arranged on the packaging film 1.

[0070] Further, the first insulation piece 3 is adhered on the battery cell 2 or the packaging film 1. For example, at least one surface of the first insulation piece 3 opposite in the first direction has an adhesive layer, which plays a role of fixation. The first insulation piece 3 can be fixed on the battery cell 2 or the packaging film 1 through the adhesive layer. Of course, a glue is arranged on the battery cell 2 or the packaging film 1, and then the first insulation piece 3 is fixed on the battery cell 2 or the packaging film 1 through the glue.

[0071] Specifically, the first bottom wall 1041 further has two edge regions arranged opposite in the second direction. When the first insulation piece 3 is arranged in the first accommodating cavity 104, to ensure the insulation effect, in the same side in the second direction, part of the first insulation piece 3 is connected to the edge region. For example, the shape of the first insulation piece 3 is similar to a "Z" shape.

[0072] Further, the first insulation piece 3 and the heat-sealing layer 103 have a coincident region, which is located on the first bottom wall 1041 and not located on the first side wall 1042. The first insulation piece 3 effectively avoids increasing the width of the battery cell 2.

[0073] In one embodiment, the first bottom wall 1041 and the first side wall 1042 form a transition region 1049 at the intersection. The distance between the edge of the first region 1043 on the same side in the second direction and the edge of the transition region 1049 is a fifth distance L5, and the fifth distance L5 is 0-10 mm. The distance between the edge of the first region 1043 on the same side in the third direction and the edge of the transition region 1049 is a sixth distance L6, and the sixth distance L6 is 0-10 mm.

[0074] After the packaging film 1 is punched, the intersection of the first bottom wall 1041 and the first side wall 1042 of the first region 1043 is a transition region 1049. If the first region 1043 falls on the transition region 1049, during the punching process of the packaging film 1, because the first accommodating cavity 104 with a certain depth is to be formed, the thickness of the transition region 1049 will be thinner than that of other regions, and the mechanical properties of the transition region 1049 will be weakened. During the battery charging and discharging process, the transition region 1049 will be easily damaged due to the expansion stress of the packaging film 1 caused by the cyclic expansion of the battery.

[0075] Therefore, by controlling L5 and L6 in the range of 0-10mm, the edge of the first area 1043 coincides with or is a certain distance from the edge of the transition area 1049, it can be ensured that the thickness of the heat-sealing layer 103 of the transition area 1049 is not further reduced, thereby ensuring the structural strength of the transition area 1049, avoiding the generation of corner cracks in the battery during the subsequent cycle expansion process, and ensuring the safety performance of the battery.

[0076] For example, L5 is 0, 1mm, 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm or within a range consisting of any two of the above values, and L6 is 0, 1mm, 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm or within a range consisting of any two of the above values.

[0077] In one embodiment, the distance between the first edge 1045 and the edge of the negative tab 203 is a seventh distance L, and the seventh distance L is 0.1mm-1.5mm. L cannot be too large or too small. If L is too large, the battery cannot utilize the space of the first area 1043, increasing the thickness of the battery; if L is too small, it increases the risk of contact between the negative tab 203 or the negative tab and the metal layer 102 of the first area 1043, and the risk of short circuit and electrochemical corrosion of the battery is larger, and at the same time, it also reduces the drop-through rate of the battery.

[0078] Therefore, by controlling L in the range of 0.2mm-1.5mm, the battery can utilize the space of the first area 1043, reducing the thickness of the battery, and at the same time, reducing the risk of contact between the negative tab 203 or the negative tab and the metal layer 102 of the first area 1043, thereby reducing the risk of short circuit and electrochemical corrosion of the battery, and improving the safety performance of the battery.

[0079] For example, L is 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm or within a range consisting of any two of the above values.

[0080] In one embodiment, the thickness D1 of the heat-seal layer 103 of the first region 1043 is 0-20 μm, and the thickness D of the heat-seal layer 103 of the first side wall 1042 is 20 μm-50 μm. When D1 is 0, it means that the heat-seal layer 103 of the first region 1043 is completely removed, which maximizes the energy density of the battery, and at this time, the metal layer 102 is exposed, and the risk of the metal layer 102 of the first region 1043 contacting the negative plate 203 or the negative tab is the largest; when D1 is not 0, the heat-seal layer 103 of the first region 1043 is partially removed, and the smaller the thickness of the heat-seal layer 103 of the first region 1043, the greater the risk of the metal layer 102 of the first region 1043 contacting the negative plate 203 or the negative tab, and vice versa. The smaller the thickness of the heat-seal layer 103 of the first region 1043, the greater the risk of the metal layer 102 of the first region 1043 contacting the negative plate 203 or the negative tab. The heat-seal layer 103 of the first region 1043 is partially or completely removed, which can reduce the thickness of the heat-seal layer 103 of the first region 1043, increase the depth of the first accommodating cavity 104, increase the space for accommodating the active material of the battery, and accommodate the battery cell 2 with a larger thickness, thereby improving the energy density of the battery.

[0081] For example, D1 is 0, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm, or within a range formed by any two of the above values, and D is 20 μm, 21 μm, 22 μm, 23 μm, 24 μm, 25 μm, 26 μm, 27 μm, 28 μm, 29 μm, 30 μm, 31 μm, 32 μm, 33 μm, 34 μm, 35 μm, 36 μm, 37 μm, 38 μm, 39 μm, 40 μm, 41 μm, 42 μm, 43 μm, 44 μm, 45 μm, 46 μm, 47 μm, 48 μm, 49 μm, 50 μm, or within a range formed by any two of the above values.

[0082] It should be noted that D and D1 cannot be 20 μm at the same time. If D is 20 μm, then D1 is less than 20 μm. If D1 is 20 μm, then D is greater than 20 μm.

[0083] Further, by cleaning part or all of the heat-seal layer 103 of the first region 1043 of the first bottom wall 1041, the thickness D1 of the heat-seal layer 103 of the first region 1043 is less than the thickness D of the heat-seal layer 103 of the first side wall 1042. After cleaning, the depth of the first accommodating cavity 104 is deeper, and the battery cell 2 with a larger thickness can be accommodated, i.e., the number of layers of the active material of the winding core can be increased, thereby increasing the energy density of the battery.

[0084] In one embodiment, the length of the first insulation piece 3 in the third direction is less than or equal to the width of the battery cell 2. If the length of the first insulation piece 3 is too long, the width of the battery cell 2 is increased. Therefore, by controlling the length of the first insulation piece 3 to be less than or equal to the width of the battery cell 2, the first insulation piece 3 effectively avoids increasing the width of the battery cell 2, thereby improving the space utilization of the battery.

[0085] Preferably, the length of the first insulation piece 3 in the third direction is equal to the width of the battery cell 2.

[0086] In one embodiment, the packaging film 1 includes a first body 106 and a second body 107 arranged opposite to each other in the first direction, the first body 106 has the first accommodating cavity 104, and the second body 107 includes a second region 1071, the thickness of the heat-seal layer 103 of the second region 1071 is less than the thickness D of the heat-seal layer 103 of the first side wall 1042. The second region 1071 is arranged on the second body 107, and the thickness of the heat-seal layer 103 of the second region 1071 is less than the thickness D of the heat-seal layer 103 of the first side wall 1042, which further reduces the thickness of the battery and further improves the energy density of the battery cell 2.

[0087] Further, in the second direction, the first body 106 and the second body 107 have a seal area 109 between one side of the first accommodating cavity 104, and the distance D3 between the second region 1071 and the seal area 109 in the second direction is 0.3mm-2.4mm.

[0088] Further, D3 cannot be too large or too small. If D3 is too small, the area of the second region 1071 is large, and if the second region 1071 coincides with the seal area 109, the thickness of the heat-seal layer 103 of the coincident region is thin, the bonding force of the seal area 109 is not strong enough, and the opening or rupture condition is prone to occur, thereby affecting the sealing performance of the packaging film 1, the impact resistance of the battery is poor, and the risk of damage to the large battery is increased; if D3 is too large, the area of the second region 1071 is small, and the battery cell 2 cannot utilize the space of the first region 1043 at all, the thickness of the battery cannot be reduced, thereby causing the energy density of the battery to be unable to be improved, and the endurance of the battery is limited.

[0089] Therefore, by controlling D3 to be in the range of 0.3mm-2.4mm, the packaging performance of the packaging film 1 is avoided from being affected by the first region 1043 being too large, the sealing performance of the battery is ensured, and at the same time, the thickness of the battery can be reduced, the energy density of the battery is improved, and the endurance of the battery is improved.

[0090] For example, D3 is 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1 mm, 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm, 1.5 mm, 1.6 mm, 1.7 mm, 1.8 mm, 1.9 mm, 2 mm, 2.1 mm, 2.2 mm, 2.3 mm, 2.4 mm, or within a range defined by any two of the above values.

[0091] In one embodiment, along the second direction, the second region 1071 has a second edge 1072 close to the edge of the positive tab 201; the battery further comprises a second insulating member 6, at least part of the second insulating member 6 is located between the second edge 1072 and the edge of the positive tab 201 along the second direction. The arrangement of the second insulating member 6 can prevent the negative tab 203 from piercing the separator 202 to make contact with the metal of the second region 1071 during the falling process, causing the short circuit failure of the battery cell 2, and improve the safety performance.

[0092] In one embodiment, the second body 107 has a second accommodating cavity 108, the second accommodating cavity 108 comprises a second bottom wall 1081 and a second side wall 1082 surrounding the second bottom wall 1081, the second bottom wall 1081 and the second side wall 1082 enclose the second accommodating cavity 108, along the first direction, the depth of the second accommodating cavity 108 is smaller than the depth of the first accommodating cavity 104, the second bottom wall 1081 has the second region 1071, at this time, the battery is a double-pit battery.

[0093] Further, the thickness of the second insulating member 6 is smaller than the thickness of the first insulating member 3, the difference between the thickness T1 of the first insulating member 3 and the thickness T3 of the second insulating member 6 is 5 μm-8 μm. Since the depth of the second accommodating cavity 108 is smaller, if the thickness of the second insulating member 6 is larger, the thickness of the battery cannot be reduced, thereby affecting the energy density of the battery; if the thickness of the second insulating member 6 is smaller, the insulation effect is poorer, increasing the risk of contact between the metal layer 102 of the second region 1071 and the negative tab 203.

[0094] Therefore, by controlling T1-T3 to be within the range of 5 μm-8 μm, the thickness of the battery is effectively reduced, the energy density of the battery is improved, and the safety performance of the battery is not affected.

[0095] Exemplarily, T1-T3 is 5 μm, 5.1 μm, 5.2 μm, 5.3 μm, 5.4 μm, 5.5 μm, 5.6 μm, 5.7 μm, 5.8 μm, 5.9 μm, 6 μm, 6.1 μm, 6.2 μm, 6.3 μm, 6.4 μm, 6.5 μm, 6.6 μm, 6.7 μm, 6.8 μm, 6.9 μm, 7 μm, 7.1 μm, 7.2 μm, 7.3 μm, 7.4 μm, 7.5 μm, 7.6 μm, 7.7 μm, 7.8 μm, 7.9 μm, 8 μm, or within a range between any two of the above values.

[0096] In one embodiment, the thickness T1 of the first insulating member 3 is 5-15 μm. T1 cannot be too large or too small. If T1 is too small, the insulation effect is poor, and the negative plate 203 is prone to break the insulation glue to cause short circuit. If T1 is too large, the energy density is prone to be lost. Therefore, by controlling T1 to be within the range of 5-15 μm, the insulation effect is ensured, the negative plate 203 is prevented from breaking the insulation glue to cause short circuit, and the energy density of the battery is ensured.

[0097] Exemplarily, T1 is 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 m, 11 m, 12 m, 13 m, 14 m, 15 μm, or within a range between any two of the above values.

[0098] It should be noted that the dimensions related to the second insulating member 6, the second region 1071, and the second side wall 1082 are the same as the dimensions related to the first insulating member 3, the first region 1043, and the first side wall 1042, and will not be described in detail here.

[0099] In another embodiment, the second body 107 is not provided with the first accommodating cavity 104, and at this time the battery is a single-pit battery.

[0100] It should be noted that the packaging film 1 is formed by stamping and then bending the film material. One accommodating cavity or two accommodating cavities can be stamped on the film material.

[0101] The application will be further described in detail below in combination with specific embodiments, which cannot be understood as limiting the scope of the application. If the specific experimental steps or conditions are not specified in the embodiments and comparative examples, the operations or conditions can be performed according to the conventional experimental steps described in the literature in the field.

[0102] The method for preparing the battery comprises:

[0103] (1) preparing the negative plate 203:

[0104] The prepared negative electrode slurry is uniformly coated on the copper foil, dried at 100°C, and then rolled and cut to obtain the negative plate 203.

[0105] (2) Preparation of the positive electrode sheet 201:

[0106] The prepared positive electrode slurry is uniformly coated on the aluminum foil to form the positive electrode sheet 201;

[0107] (3) Preparation of the separator 202:

[0108] (4) The positive electrode sheet 201, the separator 202, and the negative electrode sheet 203 are wound to obtain the battery cell 2, which is then packaged, injected, formed, double-sealed, and subjected to other steps to form the battery.

[0109] The batteries are prepared according to the parameters in Tables 1 and 2, and the batteries prepared in each example and the comparative example are subjected to electrical performance tests. The test method of the battery includes:

[0110] 1. Drop test method:

[0111] The battery cell 2 is charged at 0.7C constant current to the upper limit voltage 4.4V, and then charged at 4.4V constant voltage to 0.025C. After the charging is completed, the battery cell 2 is placed in a fixed clamp. The appearance of the battery cell 2 is checked before and after the test and photographed. The clamp is dropped freely to the ground, and the drop height is 1.5m. Each drop is dropped once on the six faces and four corners of the battery cell 2, which is one round, and a total of 10 rounds of tests are performed. The pass criteria for the drop test are: no smoke, no leakage, and a battery cell 2 pressure drop of <30mV. Among them, the battery pressure drop = voltage value before drop test / voltage value after drop test. Ten lithium ion batteries are tested for each example or comparative example, and the number of battery cells 2 that pass the drop test is recorded.

[0112] 2. Volume energy density test method:

[0113] The battery cell 2 is charged at a rate of 0.5C constant current to 4.4V, and then charged at a rate of 0.02C constant voltage to complete the charging of the battery cell 2; next, the battery cell 2 is discharged at a rate of 0.5C constant current until the voltage of the battery cell 2 decreases to 3.0V, the total capacity C discharged during the discharging process is recorded, and the actual lithium ion battery volume V is calculated. The volume energy density VED = discharge capacity C x voltage platform / battery cell 2 volume V, with the unit of Wh / L.

[0114] The test results are shown in Table 1.

[0115] Table 1: Structural parameters and performance parameters of the battery

[0116]

[0117] It should be noted that " / " in Table 1 means that there is no " / " in Table 1. The meaning of 10 / 9 PASS is that 9 out of 10 batteries pass the drop test.

[0118] From Table 1, it can be seen that:

[0119] According to the data of embodiment 1-1 to embodiment 1-4, it can be seen that the smaller D1 is, the smaller the battery thickness is, and the higher the volume energy density is. When D1 is 0, the risk of the negative plate 203 or the negative tab directly contacting the metal layer 102 increases, and the drop pass rate slightly decreases. In the comparative example 1, when the insulating piece is not arranged, the drop test cannot be passed.

[0120] According to the data of embodiment 1-1, embodiment 2-1 and embodiment 2-2, it can be seen that when the thickness T1 of the first insulating piece 3 is thin, the drop pass rate is slightly low; when the thickness T1 of the first insulating piece 3 is thick, the thickness of the battery cell 2 increases, and the energy density decreases.

[0121] According to the data of embodiment 1-1, embodiment 3-1, embodiment 3-2 and embodiment 3-3, it can be seen that the larger L2 is, the higher the short circuit risk is.

[0122] Although the embodiments of the present application are described in conjunction with the drawings, various modifications and changes can be made by those skilled in the art without departing from the spirit and scope of the present application, and such modifications and changes fall within the scope defined by the appended claims.

Claims

1. A battery, characterized by, The application relates to a packaging film (1) comprising a protective layer (101), a metal layer (102) and a heat-seal layer (103) arranged in a stack from outside to inside along a first direction, the packaging film (1) having a first accommodating cavity (104) comprising a first bottom wall (1041) and a first side wall (1042) surrounding the first bottom wall (1041), the first bottom wall (1041) and the first side wall (1042) enclosing the first accommodating cavity (104), the first bottom wall (1041) comprising a first area (1043), the thickness D1 of the heat-seal layer (103) of the first area being smaller than the thickness D of the heat-seal layer (103) of the first side wall (1042); an electric core (2) arranged in the first accommodating cavity (104), the electric core (2) comprising a positive electrode sheet (201), a diaphragm (202) and a negative electrode sheet (203) arranged in a stack, the heat-seal layer (103) of the first bottom wall (1041) facing the electric core (2) along the first direction, the edge of the negative electrode sheet (203) being beyond the edge of the positive electrode sheet (201) along a second direction, the distance between the edge of the negative electrode sheet (203) and the edge of the positive electrode sheet (201) on the same side of the second direction being a first distance L1, the first area (1043) having a first edge (1045) close to the edge of the positive electrode sheet (201) along the second direction; a first insulating member (3) at least partially arranged between the first edge (1045) and the edge of the positive electrode sheet (201) along the second direction, the first insulating member (3) having a first side (301) close to the edge of the positive electrode sheet (201) along the second direction, the second distance L2 between the first side (301) and the edge of the positive electrode sheet (201) being smaller than the first distance L1. The first distance L1 and the second distance L2 satisfy: 0<=L2 / L1<=2 / 3; And / or, the first distance L1 satisfies: 0.2mm<=L1<=2mm; And / or, the second distance L2 satisfies: 0<=L2<=1.35mm.

2. The battery of claim 1, wherein, The first insulating member (3) has a second side (302) away from the edge of the positive electrode sheet (201) on the same side of the second direction, the distance between the second side (302) and the edge of the diaphragm (202) being a third distance L3; The edge of the diaphragm (202) is beyond the edge of the negative electrode sheet (203) along the second direction, the distance between the edge of the diaphragm (202) and the edge of the negative electrode sheet (203) on the same side of the second direction being a fourth distance L4; The third distance L3 and the fourth distance L4 satisfy: L3=(1 / 3~3 / 4)L4.

3. The battery of any one of claims 1-2, wherein, The width W1 of the first insulating member (3) is greater than or equal to the width W of the first area (1043) along a third direction. ​ ​ 4. The battery of any one of claims 1-2, wherein, ​ 5. The battery of any one of claims 1-2, wherein, The electric core (2) has a flat area (204) and a circular arc area (205) arranged on both sides of the flat area (204) in a third direction, along the third direction, the width W of the first area (1043) is greater than the width W3 of the flat area (204); And / or, the first edge (1045) is located between the edge of the positive plate (201) and the edge of the negative plate (203) on the same side of the second direction.

6. The battery of any one of claims 1-2, wherein, The electric core (2) is provided with a first adhesive layer (206) on one side facing the first bottom wall (1041), along the first direction, the thickness T1 of the first insulating part (3) is less than the thickness T2 of the first adhesive layer (206).

7. The battery of any one of claims 1-2, wherein, The first insulating part (3) is arranged on at least one of the electric core (2) and the packaging film (1).

8. The battery according to any one of claims 1-2, wherein, The intersection of the first bottom wall (1041) and the first side wall (1042) forms a transition area (1049), the distance between the edge of the first area (1043) on the same side of the second direction and the edge of the transition area (1049) is a fifth distance L5, the fifth distance L5 is 0-10mm, the distance between the edge of the first area (1043) on the same side of the third direction and the edge of the transition area (1049) is a sixth distance L6, the sixth distance L6 is 0-10mm; And / or, the distance between the first edge (1045) and the edge of the negative plate (203) is a seventh distance L, the seventh distance L is 0.1mm-1.5mm; And / or, the thickness D1 of the heat-seal layer (103) of the first area (1043) is 0-20μm; And / or, the thickness D of the heat-seal layer (103) of the first side wall (1042) is 20μm-50μm.

9. The battery of any one of claims 1-2, wherein, The packaging film (1) comprises a first body (106) and a second body (107) arranged opposite along the first direction, the first body (106) has the first accommodating cavity (104), and the second body (107) comprises a second area (1071), the thickness of the heat-seal layer (103) of the second area (1071) is less than the thickness D of the heat-seal layer (103) of the first side wall (1042); Along the second direction, the first body (106) and the second body (107) have a seal area (109) between one side of the first accommodating cavity (104), along the second direction, the distance D3 between the second area (1071) and the seal area (109) is 0.3mm-2.4mm.

10. The battery of claim 9, wherein, Along the second direction, the second area (1071) has a second edge (1072) close to the edge of the positive plate (201); The second body (107) has a second accommodating cavity (108) comprising a second bottom wall (1081) and a second side wall (1082) surrounding the second bottom wall (1081), the second bottom wall (1081) and the second side wall (1082) enclosing the second accommodating cavity (108), the depth of the second accommodating cavity (108) is smaller than the depth of the first accommodating cavity (104) along the first direction, and the second bottom wall (1081) has the second area (1071); The battery further comprises a second insulating member (6), at least part of the second insulating member (6) is located between the second edge (1072) and the edge of the positive plate (201) along the second direction, the thickness of the second insulating member (6) is smaller than the thickness of the first insulating member (3), and the difference between the thickness T1 of the first insulating member (3) and the thickness T3 of the second insulating member (6) is 5-8 microns.

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