Battery

Abstract

The invention relates to the technical field of batteries, and discloses a battery, comprising: a packaging film comprising a protective layer, a metal layer and a heat sealing layer which are stacked from outside to inside along a first direction, the packaging film having a first accommodating cavity, the first accommodating cavity comprising a first bottom wall and a first side wall surrounding the first bottom wall, the first bottom wall comprising a first area, the thickness D1 of the heat sealing layer of the first area is smaller than the thickness D2 of the heat sealing layer of the first side wall; the battery cell is arranged in the first accommodating cavity, and the heat sealing layer of the first bottom wall faces the battery cell in the first direction; the first heat-conducting glue is arranged between the battery cell and the first bottom wall in the first direction, the projection of at least part of the first heat-conducting glue on the first bottom wall coincides with the first area, and the heat conductivity coefficient of the first heat-conducting glue is larger than 1.5 W / m.K and smaller than or equal to 85 W / m.K. The reduction of the thickness of the heat-sealing layer in the first area and the first heat-conducting glue facilitate the rapid transmission of the interior of the battery cell to the exterior, thereby improving the safety performance and the use performance of the battery.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and particularly to batteries. Background Art

[0002] Soft-pack lithium-ion batteries are widely used in fields such as electronic products and electric vehicles due to their high energy density, no memory effect, long cycle life, etc. With the continuous update and iteration of consumer electronic products, higher requirements are put forward for the high-rate charge and discharge and energy density of lithium-ion batteries. However, under the conditions of high-temperature furnace temperature safety tests or the working conditions of high-rate charge and discharge of batteries, a large amount of heat is generated inside the battery and is difficult to dissipate in time, resulting in a shortened life of the lithium battery, and even causing safety accidents such as fire or poor passing rate of high-temperature safety tests and explosion. Summary of the Invention

[0003] In view of this, the present invention provides a battery to solve the problem of low battery safety performance caused by the ineffective export of internal heat of the lithium battery.

[0004] The present invention provides a battery, including: a packaging film, including a protective layer, a metal layer, and a heat-sealing layer stacked from the outside to the inside along a first direction, the packaging film having a first accommodating cavity, the first accommodating cavity including a first bottom wall and a first side wall surrounding the first bottom wall, the first bottom wall and the first side wall enclosing to form the first accommodating cavity, the first bottom wall including a first region, the thickness D1 of the heat-sealing layer of the first region being less than the thickness D2 of the heat-sealing layer of the first side wall; an electric core, disposed in the first accommodating cavity, and along the first direction, the heat-sealing layer of the first bottom wall faces the electric core; a first thermal conductive adhesive, disposed between the electric core and the first bottom wall along the first direction, at least a part of the projection of the first thermal conductive adhesive on the first bottom wall coincides with the first region, and the thermal conductivity of the first thermal conductive adhesive is greater than 1.5 W / m·K and less than or equal to 85 W / m·K.

[0005] In an optional embodiment, the thickness D3 of the first thermal conductive adhesive, the thickness D1 of the heat-sealing layer of the first region, and the thickness D2 of the heat-sealing layer of the first side wall satisfy: D3 + D1 ≤ D2; and / or, the thickness D2 of the heat-sealing layer of the first side wall is greater than the thickness D3 of the first thermal conductive adhesive; and / or, the thickness D3 of the first thermal conductive adhesive is 15 μm to 40 μm; and / or, the thickness D1 of the heat-sealing layer of the first region is 0 to 20 μm; and / or, the thickness D2 of the heat-sealing layer of the first side wall is 20 μm to 50 μm; and / or, along the first direction, the projection area S of the first thermal conductive adhesive on the first bottom wall accounts for 50% to 90% of the projection area S1 of the electric core on the first bottom wall; and / or, along the first direction, the first thermal conductive adhesive is disposed on any one of the surface of the electric core facing the first region or the surface of the first region facing the electric core.

[0006] In an alternative embodiment, along the second direction, the first region has a first edge and a second edge disposed opposite to each other, the first thermal conductive adhesive has a third edge and a fourth edge disposed opposite to each other, the third edge is disposed close to the first edge, and the fourth edge is disposed close to the second edge; along the second direction, the distance L1 between the first edge and the third edge is 1 mm to 10 mm; and / or, along the second direction, the distance L2 between the second edge and the fourth edge is 1 mm to 10 mm.

[0007] In an alternative embodiment, along the third direction, the first region has a fifth edge and a sixth edge disposed opposite to each other, the first thermal conductive adhesive has a seventh edge and an eighth edge disposed opposite to each other, the seventh edge is disposed close to the fifth edge, and the eighth edge is disposed close to the sixth edge; along the third direction, the distance L3 between the fifth edge and the seventh edge is 0 - 4 mm; and / or, along the third direction, the distance L4 between the sixth edge and the eighth edge is 0 - 4 mm.

[0008] In an alternative embodiment, a first adhesive layer is disposed on one side of the battery cell facing the first bottom wall; along the first direction, the projected area of the first thermal conductive adhesive on the first bottom wall is greater than the projected area of the first adhesive layer on the first bottom wall; and / or, along the first direction, the thickness D3 of the first thermal conductive adhesive and the thickness D4 of the first adhesive layer satisfy: D3 ≥ D4.

[0009] In an alternative embodiment, the battery cell has a flat region and arc regions spaced apart from both sides of the flat region in the third direction, and along the third direction, the width W of the first region is greater than the width W3 of the flat region.

[0010] In an alternative embodiment, the battery cell includes a positive electrode sheet, a separator, and a negative electrode sheet stacked in sequence, and along the second direction, the length H1 of the first region is greater than the length H2 of the positive electrode sheet.

[0011] In an alternative embodiment, a transition region is formed at the junction of the first bottom wall and the first side wall; along the second direction, the transition region has a ninth edge and a tenth edge respectively corresponding to the first edge and the second edge of the first region, and along the third direction, the transition region has an eleventh edge and a twelfth edge respectively corresponding to the fifth edge and the sixth edge of the first region; along the second direction, the distance between the ninth edge and the first edge is W1 mm, and W1 satisfies: 0 ≤ W1 ≤ 10; and / or, along the second direction, the distance between the tenth edge and the second edge is W2 mm, and W2 satisfies: 0 ≤ W2 ≤ 10; and / or, along the third direction, the distance between the eleventh edge and the fifth edge is W3 mm, and W3 satisfies: 0 ≤ W3 ≤ 10; and / or, along the third direction, the distance between the twelfth edge and the sixth edge is W4 mm, and W4 satisfies: 0 ≤ W4 ≤ 10.

[0012] In an alternative embodiment, along the first direction, the packaging film includes a first body and a second body disposed opposite to each other. The first body has a first accommodation cavity. The second body includes a second region, and the thickness D5 of the heat-sealing layer of the second region is less than the thickness D2 of the heat-sealing layer of the first side wall. The battery further includes a second thermal conductive adhesive disposed between the battery cell and the second body, and at least a part of the second thermal conductive adhesive projects onto the second body and coincides with the second region. The thermal conductivity of the second thermal conductive adhesive is greater than 1.5 W / m·K and less than or equal to 85 W / m·K.

[0013] In an alternative embodiment, the second body has a second accommodation cavity. The second accommodation cavity includes 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 accommodation cavity. Along the first direction, the depth of the second accommodation cavity is less than the depth of the first accommodation cavity. The second bottom wall has a second region, and the thickness D6 of the heat-sealing layer of the second side wall is greater than the thickness D7 of the second thermal conductive adhesive.

[0014] The technical solution of the present application has the following advantages:

[0015] The reduction in the thickness of the heat-sealing layer of the first region and the first thermal conductive adhesive are both beneficial to quickly transfer the heat inside the battery cell to the outside, thereby improving the passing rate in the battery furnace temperature test and the cycling performance of the battery at high temperatures, so as to ensure the safety performance and service performance of the battery. The heat-sealing layer of the battery packaging film is generally a polypropylene layer with poor thermal conductivity. The reduction in the thickness of the heat-sealing layer of the first region shortens the heat transfer path on the one hand and reduces the presence of the heat-sealing layer with poor thermal conductivity on the other hand, enhancing the contact interface between the first thermal conductive adhesive and the battery cell and the packaging film, improving the thermal conductivity effect of the thermal conductive adhesive. Moreover, the reduction in the thickness of the heat-sealing layer of the first region provides an accommodation space for the setting of the first thermal conductive adhesive, avoiding the increase in the thickness of the battery and the reduction in energy density caused by the setting of the first thermal conductive adhesive.

[0016] When the thermal conductivity of the first thermal conductive adhesive disposed between the battery cell and the packaging film in the present application is in the range of 1.5 W / (m·K) - 85 W / (m·K), the heat inside the battery cell can be quickly transferred out in time, avoiding the continuous accumulation of heat resulting in the increase in the battery temperature, effectively solving the problem of low safety performance of the lithium battery caused by the ineffective export of the heat inside the lithium battery, and at the same time improving the high-temperature cycling performance of the battery.

[0017] The additional aspects and advantages of the embodiments of the present application will be partially described and shown in the subsequent description, or will be explained through the implementation of the embodiments of the present application. Description of the Drawings

[0018] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0019] Figure 1 Partial structural schematic diagram of a packaging film after cleaning according to an embodiment of the present invention;

[0020] Figure 2 For Figure 1 Structural schematic diagram of the packaging film and the first thermal conductive adhesive shown;

[0021] Figure 3 For Figure 1 Structural schematic diagram of the packaging film before cleaning shown;

[0022] Figure 4 For Figure 1 Structural schematic diagram of the packaging film, the first thermal conductive adhesive and the battery cell shown;

[0023] Figure 5 For Figure 4 Structural schematic diagram of the battery cell and the first thermal conductive adhesive shown;

[0024] Figure 6 For Figure 1 Structural schematic diagram of the packaging film before bending shown;

[0025] Figure 7 Structural schematic diagram of a battery according to an embodiment of the present invention in the second direction;

[0026] Figure 8 For Figure 7 Structural schematic diagram of the battery shown in the third direction;

[0027] Figure 9 For Figure 7 Structural schematic diagram of the packaging film and the battery cell shown;

[0028] Figure 10 For Figure 7 Partial structural schematic diagram of the packaging film shown;

[0029] Figure 11 Another cross-sectional schematic diagram of a battery according to an embodiment of the present invention in the width direction.

[0030] Explanation of reference numerals:

[0031] 1. Packaging film; 101. Protective layer; 102. Metal layer; 103. Heat-sealing layer; 104. First accommodating cavity; 1041. First bottom wall; 1042. First side wall; 1043. First region; 1045. First edge; 1046. Second edge; 1047. Fifth edge; 1048. Sixth edge; 1049. Transition region; 1052. Tenth edge; 1053. Eleventh edge; 106. First body; 107. Second body; 1071. Second region; 108. Second accommodating cavity; 1081. Second bottom wall; 1082. Second side wall;

[0032] 2. Battery cell; 201. Positive electrode sheet; 202. Separator; 203. Negative electrode sheet; 204. Straight region; 205. Arc region; 206. First adhesive layer;

[0033] 4. First thermal conductive adhesive; 401. Third edge; 402. Fourth edge; 403. Seventh edge; 404. Eighth edge;

[0034] 5. Second thermal conductive adhesive. Detailed implementation manners

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

[0036] The following combines Figures 1 to 11 to describe the embodiments of the present invention.

[0037] According to an embodiment of the present invention, a battery is provided, including: a packaging film 1, a battery cell 2, and a first thermal conductive adhesive 4. The packaging film 1 includes a protective layer 101, a metal layer 102, and a heat-sealing layer 103 stacked from outside to inside along a first direction. The packaging film 1 has a first accommodating cavity 104. The first accommodating cavity 104 includes 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 enclose the first accommodating cavity 104. The first bottom wall 1041 includes a first region 1043. The thickness D1 of the heat-sealing layer 103 in the first region 1043 is less than the thickness D2 of the heat-sealing layer 103 in the first side wall 1042. The battery cell 2 is disposed in the first accommodating cavity 104. Along the first direction, the heat-sealing layer 103 of the first bottom wall 1041 faces the battery cell 2. The first thermal conductive adhesive 4 is disposed between the battery cell 2 and the first bottom wall 1041 along the first direction. At least a part of the projection of the first thermal conductive adhesive 4 on the first bottom wall 1041 coincides with the first region 1043. The thermal conductivity of the first thermal conductive adhesive 4 is greater than 1.5 W / m·K and less than or equal to 85 W / m·K.

[0038] It should be noted that 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 inner side refers to the side of the packaging film 1 facing the battery cell 2, and the outer side 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.

[0039] Since the thickness D1 of the heat-sealing layer 103 in the first region 1043 is less than the thickness D of the heat-sealing layer 103 in the first side wall 1042, the thickness of the heat-sealing layer 103 in the first region 1043 is reduced, which is beneficial to transfer the heat inside the battery cell 2. In order to further transfer heat, a first thermal conductive adhesive 4 is disposed between the battery cell 2 and the first bottom wall 1041. At least a part of the first thermal conductive adhesive 4 is located in the first region 1043. The heat inside the battery cell 2 is transferred to the packaging film 1 through the first thermal conductive adhesive 4 and then dissipated to the outside of the battery.

[0040] Therefore, both the reduction of the thickness of the heat-sealing layer 103 in the first region 1043 and the first thermal conductive adhesive 4 are beneficial to quickly transfer the heat inside the battery cell 2 to the outside, thereby improving the passing rate in the battery furnace temperature test and the cycling performance of the battery at high temperature, and thus ensuring the safety performance and service performance of the battery. The heat-sealing layer of the battery packaging film is generally a polypropylene layer with poor thermal conductivity. The reduction of the thickness of the heat-sealing layer in the first region shortens the heat transfer path on the one hand and reduces the existence of the heat-sealing layer with poor thermal conductivity on the other hand, enhances the contact interface between the first thermal conductive adhesive and the battery cell and the packaging film, and improves the thermal conductivity effect of the thermal conductive adhesive. Moreover, the reduction of the thickness of the heat-sealing layer 103 in the first region 1043 provides a accommodating space for the setting of the first thermal conductive adhesive 4, avoiding the increase in the thickness of the battery and the reduction of the energy density caused by the setting of the first thermal conductive adhesive 4.

[0041] Furthermore, the thermal conductivity of the first thermal conductive adhesive 4 affects the heat dissipation effect. If the thermal conductivity coefficient of the first thermal conductive adhesive 4 is too small, the heat of the battery cell 2 cannot be transferred out in time, resulting in an increase in the temperature rise of the battery; if the thermal conductivity coefficient of the first thermal conductive adhesive 4 is too large, when the battery undergoes an electrochemical reaction at high temperature, the thermal conductive adhesive with a high thermal conductivity coefficient is more likely to chemically react with the electrolyte to generate gas (such as oxidation and swelling), resulting in a poor contact between the first thermal conductive adhesive 4 and the battery cell 2 and the housing, and instead, the heat cannot be quickly dissipated, deteriorating the furnace temperature passing rate of the battery. At the same time, at high temperature, the reaction between the thermal conductive adhesive with a high thermal conductivity coefficient and the electrolyte will generate gas, causing the battery to expand, resulting in a decline in the high-temperature cycle performance of the battery.

[0042] Therefore, in the present application, when the thermal conductivity coefficient of the first thermal conductive adhesive 4 provided between the battery cell and the packaging film is in the range of 1.5 W / (m·K) - 85 W / (m·K), the heat inside the battery cell 2 can be quickly transferred out in time, avoiding the continuous accumulation of heat leading to an increase in the battery temperature, effectively solving the problem of low battery safety performance caused by the ineffective export of heat inside the lithium battery, and at the same time improving the high-temperature cycle performance of the battery.

[0043] In one embodiment, the thickness D3 of the first thermal conductive adhesive 4, the thickness D1 of the heat-sealing layer 103 of the first region 1043, and the thickness D2 of the heat-sealing layer 103 of the first side wall 1042 satisfy: D3 + D1 ≤ D2. By controlling the sum of D3 and D1 to be less than or equal to D2, the thickness of the battery cell 2 is controlled, ensuring the energy density of the battery, and avoiding an increase in the battery thickness caused by the setting of the first thermal conductive adhesive 4, thereby avoiding the loss of energy density caused by the increase in the battery thickness.

[0044] In one embodiment, the thickness D2 of the heat-sealing layer 103 of the first side wall 1042 is greater than the thickness D3 of the first thermal conductive adhesive 4. By controlling D2 to be greater than D3, the thickness of the battery cell 2 can be further controlled, ensuring the energy density of the battery, and further avoiding an increase in the battery thickness caused by the setting of the first thermal conductive adhesive 4, thereby avoiding the loss of energy density caused by the increase in the battery thickness.

[0045] In one embodiment, the thickness D3 of the first thermal conductive adhesive 4 is 15 μm - 40 μm.

[0046] Furthermore, the thickness of the first thermal conductive adhesive 4 should neither be too large nor too small. If the thickness of the first conductive adhesive is too large, it occupies a large space of the battery cell 2, thereby affecting the energy density of the battery cell 2; if the thickness of the first thermal conductive adhesive 4 is too small, the thickness of the first thermal conductive adhesive 4 is too thin, which is difficult to manufacture and has poor heat dissipation performance.

[0047] Therefore, the thickness of the first thermal conductive adhesive 4 ranges from 15 μm to 40 μm, which can effectively disperse the heat of the battery cell 2, enable rapid heat transfer, occupy no space of the battery cell 2, and at the same time, facilitate manufacturing and reduce costs.

[0048] Exemplarily, D3 is 5 μm, 16 μm, 17 μm, 18 μm, 19 μm, 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, or within the range composed of any two of the above values.

[0049] In one embodiment, the thickness D1 of the heat-sealing layer 103 in the first region 1043 is 0 - 20 μm; the thickness D2 of the heat-sealing layer 103 on the first side wall 1042 is 20 μm - 50 μm.

[0050] When D1 is 0, it means that the heat-sealing layer 103 in the first region 1043 is completely removed, the depth of the first accommodation cavity 104 is deeper, the accommodation space for the battery active material is increased, a battery cell 2 with a larger thickness can be accommodated, and thus the battery energy density is improved. At the same time, when the heat-sealing layer 103 in the first region 1043 is completely removed, the metal layer 102 is exposed, and the first thermal conductive adhesive 4 is in direct contact with the metal layer 102 in the first region 1043. The heat conduction effect of the metal layer 102 is better, further improving the heat transfer efficiency of the battery cell 2 and realizing rapid heat dissipation of the battery cell 2. When D1 is not 0, the heat-sealing layer 103 in the first region 1043 is partially removed. The smaller the thickness of the heat-sealing layer 103 in the first region 1043, the easier it is for the metal layer 102 in the first region 1043 to contact the first thermal conductive adhesive 4. On the contrary, the larger the thickness of the heat-sealing layer 103 in the first region 1043, the more difficult it is for the metal layer 102 in the first region 1043 to contact the first thermal conductive adhesive 4.

[0051] Therefore, by controlling the thicknesses of D1 and D2, the thickness of the heat-sealing layer 103 in the first region 1043 can be reduced, which is beneficial to transferring the heat inside the battery cell 2 and improving the heat dissipation performance of the battery.

[0052] Exemplarily, D1 is 0, 1μm, 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, 16μm, 17μm, 18μm, 19μm, 20μm, or within the range formed by any two of the above values. D2 is 20μm, 21μm, 22μm, 23μm, 24μm, 25μm, 26μm, 27μm, 28μm, 29μm, 30μm, 31μm, 32μm, 33μm, 34μm, 35μm, 36μm, 37μm, 38μm, 39μm, 40μm, 41μm, 42μm, 43μm, 44μm, 45μm, 46μm, 47μm, 48μm, 49μm, 50μm, or within the range formed by any two of the above values.

[0053] It should be noted that D and D1 cannot be 20μm simultaneously. If D is 20μm, then D1 is less than 20μm. If D1 is 20μm, then D is greater than 20μm.

[0054] Furthermore, by cleaning part or all of the heat-sealing layer 103 in the first region 1043 of the first bottom wall 1041, the thickness D1 of the heat-sealing layer 103 in the first region 1043 is made less than the thickness D of the heat-sealing layer 103 on the first side wall 1042. After the cleaning is completed, the depth of the first accommodating cavity 104 becomes deeper, and it can accommodate a thicker battery cell 2, that is, the number of layers of the rolled-core active material can be increased, thereby increasing the battery energy density.

[0055] In one embodiment, along the first direction, the projected area S of the first thermal conductive adhesive 4 on the first bottom wall 1041 accounts for 50% - 90% of the projected area S1 of the battery cell 2 on the first bottom wall 1041.

[0056] Furthermore, S / S1 should neither be too large nor too small. If S / S1 is too small, the area of the first thermal conductive adhesive 4 is too small, and due to the different thermal conductivities of the first thermal conductive adhesive 4 and the heat-sealing layer 103, there is a large temperature difference in the battery cell 2, resulting in differences in the local kinetic performance of the battery, thus causing a non-uniform rate of lithium deintercalation / insertion reaction, reducing the cycle performance of the battery, and at the same time, it may also cause local overheating of the battery cell 2, resulting in a reduction in the passing rate of the furnace temperature test. If S / S1 is too large, the area of the first thermal conductive adhesive 4 is too large, occupying too much space of the battery cell 2, which may exceed the size of the battery cell 2, increasing the ineffective size of the battery and reducing the energy density of the battery.

[0057] Therefore, by controlling S / S1 within the range of 50% to 90%, the consistency of the internal temperature of the battery is ensured, and the temperature difference caused by different thermal conductivities is avoided, so as to prevent local overheating from leading to safety failure. At the same time, the setting of the first thermal conductive adhesive 4 does not affect the overall size of the battery cell 2, the thickness of the battery is controlled, and the energy density of the battery is ensured.

[0058] Exemplarily, S / S1 is 50%, 55%, 60%, 65%, 70%, 78%, 80%, 84%, 90% or within the range composed of any two of the above values.

[0059] In one embodiment, along the first direction, the first thermal conductive adhesive 4 is disposed on either the surface of the battery cell 2 facing the first region 1043 or the surface of the first region 1043 facing the battery cell 2. The fixing position of the first thermal conductive adhesive 4 is selected according to the manufacturing process, which has stronger flexibility.

[0060] Specifically, the first thermal conductive adhesive 4 can be disposed on the battery cell 2, or on the packaging film 1. The first thermal conductive adhesive 4 can also be divided into two parts, one part is disposed on the battery cell 2 and the other part is disposed on the packaging film 1.

[0061] Furthermore, the first thermal conductive adhesive 4 is adhered to the battery cell 2 or the packaging film 1. Exemplarily, one of the two opposite surfaces of the first thermal conductive adhesive 4 along the first direction has an adhesive layer, and the adhesive layer plays a fixing role. The first thermal conductive adhesive 4 can be fixed to the battery cell 2 or the packaging film 1 through the adhesive layer. Of course, a colloid is provided on the battery cell 2 or the packaging film 1, and then the first insulating member is fixed to the battery cell 2 or the packaging film 1 through the colloid. The colloid is disposed on the surface of the battery cell 2 or the inner side of the packaging film 1 by spraying.

[0062] In one embodiment, along the second direction, the first region 1043 has a first edge 1045 and a second edge 1046 which are oppositely arranged. The first thermal conductive adhesive 4 has a third edge 401 and a fourth edge 402 which are oppositely arranged. The third edge 401 is disposed close to the first edge 1045, and the fourth edge 402 is disposed close to the second edge 1046. Along the second direction, the distance L1 between the first edge 1045 and the third edge 401 is 1 mm to 10 mm. Along the second direction, the distance L2 between the second edge 1046 and the fourth edge 402 is 1 mm to 10 mm.

[0063] Furthermore, neither L1 nor L2 can be too large or too small. If L1 and L2 are too small, it is difficult to meet the processing accuracy requirements, and it is difficult to ensure the rationality of the position setting of the first thermal conductive adhesive 4, thus unable to better exert the heat dissipation effect. If L1 and L2 are too large, due to the different thermal conductivity coefficients of the first thermal conductive adhesive 4 and the heat-sealing layer 103, there will be a certain temperature difference in the battery cell 2, that is, it cannot ensure uniform heat dissipation for the battery cell, resulting in differences in the local kinetic performance of the battery, and thus an uneven rate of lithium deintercalation reaction occurs, reducing the cycle performance of the battery.

[0064] Therefore, controlling L1 and L2 within the above range can ensure the consistency of the internal temperature of the battery, avoid temperature differences caused by the different thermal conductivity coefficients of the thermal conductive adhesive and the heat-sealing layer 103 of the packaging film, resulting in differences in the local kinetic performance of the battery, and thus an uneven rate of lithium deintercalation reaction occurs, reducing the cycle performance of the battery, or causing local overheating of the battery to trigger thermal safety failure. At the same time, it reduces the processing accuracy and meets the manufacturing requirements.

[0065] Exemplarily, L1 is 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm or within the range composed of any two of the above values, and L2 is 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm or within the range composed of any two of the above values.

[0066] In one embodiment, along the third direction, the first region 1043 has a relatively arranged fifth edge 1047 and sixth edge 1048, and the first thermal conductive adhesive 4 has a relatively arranged seventh edge 403 and eighth edge 404. The seventh edge 403 is arranged close to the fifth edge 1047, and the eighth edge 404 is arranged close to the sixth edge 1048. Along the third direction, the distance L3 between the fifth edge 1047 and the seventh edge 403 is 0 - 4 mm. Along the third direction, the distance L4 between the sixth edge 1048 and the eighth edge 404 is 0 - 4 mm.

[0067] Furthermore, if L3 and L4 are too large, due to the different thermal conductivity coefficients of the first thermal conductive adhesive 4 and the heat-sealing layer 103, there will be a large temperature difference in the battery cell 2, resulting in differences in the local kinetic performance of the battery, and thus an uneven rate of lithium deintercalation reaction occurs, reducing the cycle performance of the battery.

[0068] Therefore, controlling L3 and L4 within the above range to ensure uniform heat transfer inside the battery cell 2 can ensure the consistency of the internal temperature of the battery, avoid temperature differences caused by the different thermal conductivity coefficients of the thermal conductive adhesive and the heat-sealing layer 103 of the packaging film, exacerbating battery side reactions and local overheating leading to safety failure. And, after setting the first thermal conductive adhesive 4, the thickness consistency of the battery cell 2 is good, avoiding poor thickness consistency caused by setting the thermal conductive adhesive.

[0069] Exemplarily, L3 is 0, 1 mm, 2 mm, 3 mm, 4 mm, or within the range formed by any two of the above values, and L4 is 0, 1 mm, 2 mm, 3 mm, 4 mm, or within the range formed by any two of the above values.

[0070] In one embodiment, a first adhesive layer 206 is provided on the side of the battery cell 2 facing the first bottom wall 1041; along the first direction, the projected area of the first thermal conductive adhesive 4 on the first bottom wall 1041 is larger than the projected area of the first adhesive layer 206 on the first bottom wall 1041. Since the thermal conductivity of the first adhesive layer 206 is poor, if the area of the first thermal conductive adhesive 4 is smaller than the area of the first adhesive layer 206, the first thermal conductive adhesive 4 cannot directly contact the battery cell 2, resulting in poor heat conduction effect.

[0071] Therefore, controlling the area of the first thermal conductive adhesive 4 to be larger than the area of the first adhesive layer 206 can ensure a good heat conduction effect, which is beneficial to the rapid transfer inside the battery cell 2, and further improves the safety performance of the battery.

[0072] Furthermore, the first adhesive layer 206 is made of hot melt adhesive or the like. The hot melt adhesive is usually a polymer material. The first adhesive layer can better bond and fix the first thermal conductive adhesive 4 and the battery cell 2, increasing the adhesive force between the two, thereby further enhancing the heat conduction effect of the first thermal conductive adhesive 4.

[0073] In one embodiment, along the first direction, the thickness D3 of the first thermal conductive adhesive 4 and the thickness D4 of the first adhesive layer 206 satisfy: D3 ≥ D4. The first adhesive layer 206 needs to have a certain thickness to ensure the fixing effect of the first thermal conductive adhesive 4 and the battery cell 2. However, if the thickness of the first adhesive layer 206 is too large, the heat conduction effect will be reduced. Therefore, controlling D3 ≥ D4 can reduce the influence of the first adhesive layer 206 on the heat conduction efficiency and ensure the heat conduction efficiency of the first thermal conductive adhesive 4. It can be understood that in this embodiment, the first adhesive layer 206 and the first thermal conductive adhesive 4 can exist in the battery at the same time; in another embodiment, only the first thermal conductive adhesive 4 can be provided between the battery cell 2 and the packaging film 1, and at this time, the first thermal conductive adhesive 4 can have a certain viscosity.

[0074] In one embodiment, the battery cell 2 has a flat region 204 and arc regions 205 spaced apart from both sides of the flat region 204 in the third direction. Along the third direction, the width W of the first region 1043 is larger than the width W3 of the flat region 204.

[0075] By controlling the width W of the first region 1043 such that the two opposite edges of the first region 1043 in the third direction do not coincide with the flat region 204. On the one hand, by setting the first region not to coincide with the flat region 204, the overall thickness of the battery can be effectively reduced and the energy density can be improved. On the other hand, by setting the position of the first region 1043, a suitable space can be provided for the first thermal conductive adhesive 4, preventing the first thermal conductive adhesive 4 from occupying the space of the battery cell 2, ensuring the energy density of the battery, and avoiding poor thickness consistency of the battery caused by the setting of the first thermal conductive adhesive 4, which affects the performance of the battery.

[0076] In one embodiment, the battery cell 2 includes a positive electrode sheet 201, a separator 202, and a negative electrode sheet 203 that are stacked in sequence. Along the second direction, the length H1 of the first region 1043 is greater than the length H2 of the positive electrode sheet 201. On the same side in the second direction, the edge of the first region 1043 close to the positive electrode sheet extends beyond the edge of the positive electrode sheet 201 (as Figure 9 shown), so that the setting of the first region 1043 can maximize the reduction of the overall thickness of the battery and improve the energy density of the battery. Further, in order to ensure the safety of the battery and avoid a short-circuit problem caused by the negative electrode at the edge of the battery contacting the first region, on the same side in the second direction, the edge of the first region 1043 close to the positive electrode sheet is located between the edge of the positive electrode sheet 201 and the edge of the negative electrode sheet 203 (not shown in the figure).

[0077] In one embodiment, a transition region 1049 is formed at the junction of the first bottom wall 1041 and the first side wall 1042; along the second direction, the transition region 1049 has a ninth edge and a tenth edge 1052 respectively corresponding to the first edge 1045 and the second edge 1046 of the first region 1043, and along the third direction, the transition region 1049 has an eleventh edge 1053 and a twelfth edge respectively corresponding to the fifth edge 1047 and the sixth edge 1048 of the first region 1043; along the second direction, the distance between the ninth edge and the first edge 1045 is W1 mm, and W1 satisfies: 0 ≤ W1 ≤ 10; along the second direction, the distance between the tenth edge 1052 and the second edge 1046 is W2 mm, and W2 satisfies: 0 ≤ W2 ≤ 10; along the third direction, the distance between the eleventh edge 1053 and the fifth edge 1047 is W3 mm, and W3 satisfies: 0 ≤ W3 ≤ 10; along the third direction, the distance between the twelfth edge and the sixth edge 1048 is W4 mm, and W4 satisfies: 0 ≤ W4 ≤ 10.

[0078] After the forming of the packaging film 1 is completed, the transition area 1049 is at the junction of the first bottom wall 1041 and the first side wall 1042 of the first area 1043. During the forming process of the packaging film 1, in order to form the first accommodating cavity 104 with a certain depth, the thickness of the transition area 1049 becomes thinner than that of other areas. If the first area 1043 falls within the transition area 1049, the thickness of the transition area 1049 further decreases, and the mechanical strength drops. During the charging and discharging cycle expansion of the battery, expansion stress will be generated on the packaging film 1, which may lead to the easy breakage of the transition area 1049.

[0079] Therefore, by controlling W1, W2, W3, and W4 within the above ranges, the edge of the first area 1043 coincides with or has a certain distance from the edge of the transition area 1049, which can ensure that the thickness of the heat-sealing layer 103 in the transition area 1049 will not be further reduced, thereby ensuring the structural strength of the transition area 1049, reducing the risk of breakage of the transition area 1049 of the packaging film 1 during the charging and discharging cycle expansion of the battery, and ensuring the safety performance of the battery.

[0080] Exemplarily, W1 is 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or within the range composed of any two of the above values; W2 is 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or within the range composed of any two of the above values; W3 is 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or within the range composed of any two of the above values; W4 is 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or within the range composed of any two of the above values.

[0081] In one embodiment, along the first direction, the packaging film 1 includes a first body 106 and a second body 107 arranged oppositely. The first body 106 has the first accommodating cavity 104. The second body 107 includes a second area 1071, and the thickness D5 of the heat-sealing layer 103 in the second area 1071 is less than the thickness D2 of the heat-sealing layer 103 of the first side wall 1042. By providing the second area 1071 on the second body 107 and making the thickness of the heat-sealing layer 103 in the second area 1071 less than the thickness D2 of the heat-sealing layer 103 of the first side wall 1042, the thickness of the battery is further reduced, and the energy density of the battery cell 2 is further improved.

[0082] In one embodiment, the battery further includes a second thermal conductive adhesive 5 disposed between the battery cell 2 and the second body 107. At least a part of the projection of the second thermal conductive adhesive 5 on the second body 107 coincides with the second region 1071. The thermal conductivity of the second thermal conductive adhesive 5 is greater than 1.5 W / m·K and less than or equal to 85 W / m·K. The first thermal conductive adhesive 4 and the second thermal conductive adhesive 5 are disposed opposite to each other along the first direction. Heat inside the battery cell 2 is transferred out from both sides of the battery cell 2 along the second direction through the first thermal conductive adhesive 4 and the second thermal conductive adhesive 5, improving the heat transfer efficiency, ensuring uniform heat transfer inside the battery, thereby improving the passing rate in the battery furnace temperature test and the cycling performance of the battery at high temperature, and thus ensuring the safety performance and service life of the battery. The heat-sealing layer of the battery packaging film is generally a polypropylene layer with poor thermal conductivity. Reducing the thickness of the heat-sealing layer in the second region shortens the heat transfer path on the one hand and reduces the presence of the heat-sealing layer with poor thermal conductivity on the other hand, enhancing the contact interface between the second thermal conductive adhesive and the battery cell and the packaging film, improving the thermal conductivity effect of the thermal conductive adhesive. Moreover, reducing the thickness of the heat-sealing layer 103 in the second region 1071 provides a accommodation space for the setting of the second thermal conductive adhesive 5, avoiding an increase in the thickness of the battery and a decrease in the energy density caused by the setting of the second thermal conductive adhesive 5.

[0083] Furthermore, the thermal conductivity of the second thermal conductive adhesive 5 affects the heat dissipation effect. If the thermal conductivity of the second thermal conductive adhesive 5 is too small, the heat of the battery cell 2 cannot be transferred out in time, resulting in an increase in the temperature rise of the battery. If the thermal conductivity of the second thermal conductive adhesive 5 is too large, when the battery undergoes an electrochemical reaction at high temperature, the thermal conductive adhesive with a high thermal conductivity is more likely to chemically react with the electrolyte to generate gas (such as oxidation and swelling), resulting in a poor contact between the second thermal conductive adhesive 5 and the battery cell 2 and the housing, and instead unable to quickly conduct out the heat, deteriorating the passing rate of the battery furnace temperature. At the same time, at high temperature, the reaction between the thermal conductive adhesive with a high thermal conductivity and the electrolyte will generate gas, causing the battery to expand, resulting in a decline in the high-temperature cycling performance of the battery.

[0084] Therefore, when the thermal conductivity of the second thermal conductive adhesive 5 is in the range of 1.5 W / (m·K) - 85 W / (m·K), the heat inside the battery cell 2 can be quickly transferred out in time, avoiding the continuous accumulation of heat leading to an increase in the battery temperature, effectively solving the problem of low safety performance of the lithium battery caused by the ineffective export of internal heat, and at the same time improving the high-temperature cycling performance of the battery.

[0085] In one embodiment, the second body 107 has a second accommodation cavity 108. The second accommodation cavity 108 includes 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 to form the second accommodation cavity 108. Along the first direction, the depth of the second accommodation cavity 108 is less than that of the first accommodation cavity 104. The second bottom wall 1081 has a second region 1071. At this time, the battery is a double-pit battery. The thickness D6 of the heat-sealing layer 103 of the second side wall 1082 is greater than the thickness D7 of the second thermal conductive adhesive 5. By controlling D6 to be greater than D7, the thickness of the battery cell 2 can be further controlled, the energy density of the battery can be ensured, and further, it can be avoided that the battery thickness increases due to the setting of the second thermal conductive adhesive 5, and further, the energy density loss caused by the increase in the battery thickness can be avoided.

[0086] It should be noted that the dimensions related to the second thermal conductive adhesive 5, the second region 1071, and the second side wall 1082 are the same as those related to the first thermal conductive adhesive 4, the first region 1043, and the first side wall 1042, and will not be elaborated here in detail.

[0087] In another embodiment, the second body 107 is not provided with an accommodation cavity. At this time, the battery is a single-pit battery.

[0088] It should be noted that the packaging film 1 is formed by first stamping and then bending the film material. One or two accommodation cavities can be stamped on the film material.

[0089] In one embodiment, the first thermal conductive adhesive 4 and the second thermal conductive adhesive 5 are of a one-piece structure. Compared with an arcuate or other form of thermal conductive adhesive, the path for the electrolyte to enter the thermal conductive adhesive is the least, which can reduce the swelling, shedding or wrinkling of the conductive adhesive caused by the long-term placement of the thermal conductive adhesive in the electrolyte environment.

[0090] In one embodiment, the heat-sealing layer 103 is generally a polypropylene layer, the metal layer 102 is generally an aluminum layer, and the protective layer is generally a nylon layer.

[0091] The following further describes the present application in detail with specific embodiments. These embodiments should not be construed as limiting the scope claimed by the present application. For those without specific experimental steps or conditions indicated in the embodiments and comparative examples, the operations or conditions of the conventional experimental steps described in the literature in this field can be followed.

[0092] The method for preparing a battery includes:

[0093] (1) Prepare the negative electrode sheet 203:

[0094] Uniformly coat the prepared negative electrode paste on the copper foil, dry it at 100 °C, and perform rolling and slitting to obtain the negative electrode sheet 203;

[0095] (2) Preparation of the positive electrode sheet 201:

[0096] Coat the prepared positive electrode paste evenly on the aluminum foil to form the positive electrode sheet 201;

[0097] (3) Preparation of the separator 202:

[0098] (4) Wind the positive electrode sheet 201, the separator 202, and the negative electrode sheet 203 to obtain the battery cell 2, and then make the battery through steps such as encapsulation, liquid injection, formation, secondary sealing, and grading.

[0099] Prepare the battery according to the parameters in Table 1 and Table 2, and conduct electrical performance tests on the batteries prepared in each example and comparative example. The test methods for the batteries include:

[0100] 1. Furnace temperature test method:

[0101] Charge the battery cell 2 at a constant current of 0.7C to the upper limit voltage of 4.4V, and then charge it at a constant voltage of 4.4V to 0.025C. After charging is completed, place the battery cell 2 in an oven with an initial temperature of 25 ± 3°C, and increase the temperature at a rate of 5 ± 2°C / min to the set target temperature (135°C), and maintain the target temperature for 60 minutes, and then end the test. The judgment criterion for passing the furnace temperature test is that the battery cell 2 does not catch fire or explode. If the temperature of the battery cell 2 continues to rise to catch fire or explode during the test, the test fails. For each example or comparative example, 10 battery cells 2 are used as parallel samples for testing, and the number of battery cells 2 passing the furnace temperature test is recorded.

[0102] 2. Volume energy density test method:

[0103] Charge the battery cell 2 at a constant current of 0.5C to 4.4V, and then charge it at a constant voltage to 0.02C to complete the charging of the battery cell 2; then discharge it at a constant current of 0.5C until the voltage of the battery cell 2 drops to 3.0V, record the total capacity C released during the discharge process, and calculate the actual volume V of the lithium-ion battery. VED = discharge capacity C × voltage platform / volume V of the battery cell 2, with the unit of Wh / L.

[0104] 3. Capacity retention rate test method:

[0105] Before the test starts, at 25°C, let it stand for 10 minutes, discharge it at 0.2C to 3.0V, and let it stand for 10 minutes; charge it at a constant current of 1C to the upper limit voltage of 4.4V, and then charge it at a constant voltage of 4.4V to 0.02C. After standing for 10 minutes, discharge it at 0.2C to 3.0V, and record it as the initial capacity.

[0106] Let it stand for 10 min, charge at a constant current of 1C to the upper limit voltage of 4.4V, and then charge at a constant voltage of 4.4V to 0.02C. After being fully charged, let it stand at 45°C, discharge at 0.5C to 3V, and then let it stand for 10 min; charge at 1C until full, charge at a constant current of 1C to the upper limit voltage of 4.4V, and then charge at a constant voltage of 4.4V to 0.02C. Discharge and charge are one cycle, and repeat 1000 times. Record the last discharge capacity as the cycle capacity. Capacity retention rate = cycle capacity / initial capacity × 100%.

[0107] The above test results are shown in Table 1.

[0108] Table 1 Structural parameters and performance parameters of the battery

[0109]

[0110]

[0111] It should be noted that " / " in Table 1 means non-existent, and the meaning of 9 / 10 PASS is that 9 out of 10 batteries pass the furnace temperature test.

[0112] As can be seen from Table 1:

[0113] According to the data of Examples 1-1 to 1-4 and Comparative Examples 1 to 3, it can be seen that when the first thermal conductive adhesive 4 is not provided, the heat conduction efficiency is slow and the furnace temperature passing rate is low; when the first thermal conductive adhesive 4 is provided, the thermal conductivity is too low and the furnace temperature passing rate is low; when the thermal conductivity is too high, the furnace temperature passing rate is low and the high-temperature cycle performance of the battery decays. Therefore, when the thermal conductivity of the first thermal conductive adhesive 4 is in the range of 1.5 W / (m·K) - 85 W / (m·K), the furnace temperature passing rate of the battery is high, and the capacity retention rate during the high-temperature cycle of the battery is also relatively high, improving the cycle performance of the battery.

[0114] According to the data of Example 1-1, Examples 2-1 to 2-3 and Comparative Example 2, it can be seen that when D1 is too large, it is not conducive to heat conduction, the heat conduction efficiency is slow, and the furnace temperature passing rate decreases. Therefore, when D1 is in the range of 0 - 20 μm, the furnace temperature passing rate is high.

[0115] According to the data of Example 1-1, Examples 3-1 to 3-3, it can be seen that the larger D3 is, the more space the battery occupies and the lower the energy density of the battery.

[0116] According to the data of Example 1-1, Examples 3-1 to 3-5, it can be seen that when L1, L2, L3, and L4 are too large, the furnace temperature passing rate of the battery decreases, and the capacity retention rate during the high-temperature cycle of the battery also decreases. Therefore, when L1, L2, L3, and L4 are in a suitable range, the furnace temperature passing rate is high, and the capacity retention rate during the high-temperature cycle of the battery is also relatively high, improving the cycle performance of the battery.

[0117] It should be noted that in Examples 2-1 to 2-3 and Examples 3-1 to 3-5, the thickness of the packaging film 1 is 113 microns, and the thickness D2 of the heat-sealing layer 103 of the first side wall 1042 is 45 microns.

[0118] Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations fall within the scope defined by the appended claims.

Claims

1. A battery, characterized in that: include: A packaging film (1), comprising a protective layer (101), a metal layer (102) and a heat-sealing layer (103) stacked from outside to inside along a first direction, the packaging film (1) having a first accommodating cavity (104), the 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 region (1043), the thickness D1 of the heat-sealing layer (103) in the first region (1043) being smaller than the thickness D2 of the heat-sealing layer (103) in the first side wall (1042); A battery core (2) is arranged in the first accommodating cavity (104), and along the first direction, the heat sealing layer (103) of the first bottom wall (1041) is arranged facing the battery core (2); A first thermally conductive adhesive (4) is arranged between the battery core (2) and the first bottom wall (1041) along the first direction, a projection of at least part of the first thermally conductive adhesive (4) on the first bottom wall (1041) coincides with the first area (1043), and a thermal conductivity coefficient of the first thermally conductive adhesive (4) is greater than 1.5 W / m·K and less than or equal to 85 W / m·K.

2. The battery according to claim 1, characterized in that The thickness D3 of the first thermally conductive adhesive (4), the thickness D1 of the heat-sealing layer (103) of the first region (1043), and the thickness D2 of the heat-sealing layer (103) of the first side wall (1042) satisfy: D3+D1≤D2; and / or, a thickness D2 of the heat-sealing layer (103) of the first side wall (1042) is greater than a thickness D3 of the first thermally conductive adhesive (4); and / or, the thickness D3 of the first thermally conductive adhesive (4) is 15 μm to 40 μm; and / or, the thickness D1 of the heat-sealing layer (103) in the first region (1043) is 0 to 20 μm; and / or, the thickness D2 of the heat-sealing layer (103) of the first side wall (1042) is 20 μm to 50 μm; and / or, along the first direction, a projection area S of the first thermally conductive adhesive (4) on the first bottom wall (1041) accounts for 50% to 90% of a projection area S1 of the battery cell (2) on the first bottom wall (1041); And / or, along the first direction, the first thermally conductive adhesive (4) is disposed on any one of a surface of the battery cell facing the first region (2) or a surface of the first region (1043) facing the battery cell.

3. The battery according to any one of claims 1 to 2, characterized in that Along the second direction, the first region (1043) has a first edge (1045) and a second edge (1046) that are arranged opposite to each other, and the first thermally conductive adhesive (4) has a third edge (401) and a fourth edge (402) that are arranged opposite to each other, the third edge (401) is arranged close to the first edge (1045), and the fourth edge (402) is arranged close to the second edge (1046); Along the second direction, a distance L1 between the first edge (1045) and the third edge (401) is 1 mm to 10 mm; And / or, along the second direction, a distance L2 between the second edge (1046) and the fourth edge (402) is 1 mm to 10 mm.

4. The battery according to claim 3, characterized in that Along the third direction, the first region (1043) has a fifth edge (1047) and a sixth edge (1048) arranged opposite to each other, and the first thermally conductive adhesive (4) has a seventh edge (403) and an eighth edge (404) arranged opposite to each other, the seventh edge (403) is arranged close to the fifth edge (1047), and the eighth edge (404) is arranged close to the sixth edge (1048); Along the third direction, a distance L3 between the fifth edge (1047) and the seventh edge (403) is 0-4 mm; And / or, along the third direction, a distance L4 between the sixth edge (1048) and the eighth edge (404) is 0-4 mm.

5. The battery according to any one of claims 1 to 2, characterized in that A first adhesive layer (206) is provided on a side of the battery core (2) facing the first bottom wall (1041); Along the first direction, a projection area of ​​the first thermally conductive adhesive (4) on the first bottom wall (1041) is greater than a projection area of ​​the first adhesive layer (206) on the first bottom wall (1041); And / or, along the first direction, the thickness D3 of the first thermally conductive adhesive (4) and the thickness D4 of the first adhesive layer (206) satisfy: D3 ≥ D4.

6. The battery according to any one of claims 1 to 2, characterized in that The battery cell (2) comprises a straight region (204) and arc regions (205) arranged at intervals on both sides of the straight region (204) in a third direction, and along the third direction, a width W of the first region (1043) is greater than a width W3 of the straight region (204).

7. The battery according to any one of claims 1 to 2, characterized in that The battery cell (2) comprises a positive electrode sheet (201), a separator (202) and a negative electrode sheet (203) which are stacked in sequence. Along the second direction, a length H1 of the first region (1043) is greater than a length H2 of the positive electrode sheet (201).

8. The battery according to claim 4, characterized in that A transition zone (1049) is formed at the junction of the first bottom wall (1041) and the first side wall (1042); Along the second direction, the transition zone (1049) has a ninth edge and a tenth edge (1052) respectively arranged corresponding to the first edge (1045) and the second edge (1046) of the first region (1043); along the third direction, the transition zone (1049) has an eleventh edge (1053) and a twelfth edge respectively arranged corresponding to the fifth edge (1047) and the sixth edge (1048) of the first region (1043); Along the second direction, the distance between the ninth edge and the first edge (1045) is W1 mm, and W1 satisfies: 0≤W1≤10; and / or, along the second direction, the distance between the tenth edge (1052) and the second edge (1046) is W2 mm, and W2 satisfies: 0≤W2≤10; and / or, along the third direction, the distance between the eleventh edge (1053) and the fifth edge (1047) is W3 mm, and W3 satisfies: 0≤W3≤10; And / or, along the third direction, the distance between the twelfth edge and the sixth edge (1048) is W4 mm, and W4 satisfies: 0≤W4≤10.

9. The battery according to any one of claims 1 to 2, characterized in that Along the first direction, the packaging film (1) comprises a first body (106) and a second body (107) arranged opposite to each other, the first body (106) having the first accommodating cavity (104), the second body (107) comprising a second region (1071), and a thickness D5 of the heat-sealing layer (103) of the second region (1071) being smaller than a thickness D2 of the heat-sealing layer (103) of the first side wall (1042); The battery further comprises a second thermally conductive adhesive (5), the second thermally conductive adhesive (5) being arranged between the battery core (2) and the second body (107), at least a portion of the projection of the second thermally conductive adhesive (5) on the second body (107) being coincident with the second region (1071), and the thermal conductivity of the second thermally conductive adhesive (5) being greater than 1.5 W / m·K and less than or equal to 85 W / m·K.

10. The battery according to claim 9, characterized in that The second body (107) has a second accommodating cavity (108), the second accommodating cavity (108) includes 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 less than the depth of the first accommodating cavity (104), the second bottom wall (1081) has the second area (1071), and the thickness D6 of the heat sealing layer (103) of the second side wall (1082) is greater than the thickness D7 of the second thermal conductive adhesive (5).

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