Battery and battery pack

Abstract

The present invention relates to the technical field of batteries, and discloses a battery and a battery pack, the battery comprises: a steel shell, at least one end of which is provided with an opening; the battery cover plate blocks the opening of the steel shell and is welded with the shell to form a welding mark, the battery cover plate and the shell define a containing space, the battery cover plate comprises a cover plate body, the cover plate body is made of steel, the cover plate body comprises a body structure and a covering part, the covering part is arranged around the body structure, the body structure comprises an embedded part, and the embedded part is arranged in the containing space. The embedded part is used for extending into the shell from the opening, the covering part and the opening surface of the shell are at least partially overlapped, the thickness of the embedded part is a, the thickness of the covering part is b in the thickness direction of the battery cover plate, and a is greater than b, and 0.15 < = b / a < = 0.85. While the welding quality of the battery cover plate and the shell is ensured, the heat dissipation capability of the battery cover plate and the energy density of the battery are ensured.

Description

[0001] This application is a divisional application of the invention patent application with publication number CN202411381130.4. The application date of the original application is: 2024.09.30; the application number is: 202411381130.4; the name of the invention is: "Battery cover, battery and battery pack". Technical Field

[0002] The present invention relates to the technical field of batteries, and in particular to batteries and battery packs. Background Art

[0003] The battery usually includes an internal battery structure and an external battery structure. The external battery structure generally includes a shell and a battery cover. The shell and the battery cover form a closed space. The internal battery structure includes a battery cell, which is arranged in the closed space. The shell and the battery cover are usually connected by tilted welding. The welding process will generate a lot of heat. If the heat is not dissipated in time, it is easy to cause the internal temperature of the battery to be too high, affecting the battery performance. Especially for steel shells, the melting point of steel is high, and the heat required for welding is large. The heat is transferred to the internal battery cell, which is easy to cause damage to the battery cell. Summary of the invention

[0004] In view of this, the present invention provides a battery and a battery pack to solve the problem in the prior art that the heat generated during the welding process of the battery cover and the shell cannot be dissipated in time, causing the internal temperature of the battery to be too high and causing damage to the battery cell.

[0005] In a first aspect, the present invention provides a battery, comprising: a shell, the shell is made of steel, and at least one end of the shell has an opening; a battery cover plate, which blocks the opening of the steel shell and is welded to the shell to form a weld mark, the battery cover plate and the shell are enclosed to form a accommodating space, the battery cover plate comprises a cover plate body, the cover plate body is made of steel, the shell comprises a side wall, the side wall is welded to the cover plate body, the cover plate body comprises a body structure and a covering portion, the covering portion is arranged around the body structure, the body structure comprises an embedded portion, the embedded portion is used to extend into the shell from the opening, the covering portion at least partially overlaps with the opening surface of the shell, along the thickness direction of the battery cover plate, the thickness of the embedded portion is a, and the thickness of the covering portion is b, satisfying a>b, 0.15≤b / a≤0.85; a battery cell, which is arranged in the accommodating space; a pole assembly is arranged on the cover plate body, the battery cell comprises a battery cell body and a pole ear, the pole ear is led out in the length direction of the battery cell body, and the pole ear is electrically connected to the pole assembly.

[0006] The covering portion has a smaller thickness, and the heat generated by the welding of the battery cover and the shell can be quickly dissipated through the covering portion, thereby improving the heat dissipation effect of the battery, thereby reducing the heat transferred to the inside of the battery, avoiding excessive internal temperature of the battery, and further avoiding damage to the battery cell; at the same time, the embedded portion has a larger thickness, and the path for the heat generated by the welding of the battery cover and the shell to be transferred to the inside of the battery is longer, further reducing the heat transferred to the inside of the battery. Moreover, if the value of b / a is too large, that is, the value of a is too small and / or the value of b is too large, when the value of a is too small, that is, the embedded part is too thin, there is a risk of welding through the embedded part during the tilt welding process, and the cover body and the shell are both made of steel, and the welding of the battery cover and the shell requires more heat, which will also increase the risk of the embedded part being welded through. At the same time, the heat generated by welding is more easily transferred to the interior of the battery and cause damage to the battery cell. When the value of b is too large, that is, the cover part is too thick, the heat dissipation capacity of the cover part is weakened, and the heat generated by welding cannot be dissipated in time, resulting in an increase in the heat transferred to the interior of the battery; if the value of b / a is too small, that is, the value of a is too large and / or the value of b is too small, when the value of a is too large, that is, the embedded part is too thick, the embedded part occupies too much space inside the shell, resulting in a decrease in the energy density of the battery, and when the value of b is too small, that is, the cover part is too thin, there is a risk of the cover part being welded through during the welding process. Therefore, the value of the ratio b / a of the thickness a of the embedded portion and the thickness b of the covering portion is controlled to ensure the heat dissipation capacity of the battery cover and the energy density of the battery while ensuring the welding quality of the battery cover and the shell.

[0007] In a second aspect, the present invention further provides a battery pack, comprising the above-mentioned battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0009] Figure 1 It is a schematic diagram of the cross-sectional structure of a cover plate body in the length direction and the thickness direction according to an embodiment of the present invention;

[0010] Figure 2 It is a schematic diagram of the cross-sectional structure of another cover plate body in the length direction and the thickness direction according to an embodiment of the present invention;

[0011] Figure 3 for Figure 1 The schematic diagram of the cross-sectional structure of the cover body and the shell in the length direction and the thickness direction after being assembled is shown;

[0012] Figure 4 for Figure 3 The enlarged schematic diagram of point A in the middle;

[0013] Figure 5 A schematic structural diagram of a battery cover, a housing, a battery cell and a pole assembly of a battery according to an embodiment of the present invention;

[0014] Figure 6 A schematic structural diagram of a battery cover, a shell and a battery cell of another battery according to an embodiment of the present invention;

[0015] Figure 7 A schematic structural diagram of a battery cover, a housing and a pole assembly of another battery according to an embodiment of the present invention;

[0016] Figure 8 Schematic diagram of the welding structure of the battery cover and the shell according to an embodiment of the present invention.

[0017] Description of reference numerals:

[0018] 1. Cover plate body; 11. Embedded part; 111. Groove; 112. Remaining part; 12. Covering part; 13. Connecting part; 2. Shell; 21. Side wall; 22. Top wall; 3. Battery cell; 31. Battery cell body; 32. Pole ear; 4. Pole column assembly; 5. Weld mark. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0020] Combine the following Figures 1 to 8 , describing an embodiment of the present invention.

[0021] According to an embodiment of the present invention, on the one hand, a battery cover is provided, which is used to block the opening of the steel shell 2, including:

[0022] The cover body 1 is made of steel. The cover body 1 includes a main body structure and a covering portion 12. The covering portion 12 is arranged around the main body structure. The main body structure includes an embedded portion 11. The embedded portion 11 is used to extend into the interior of the shell 2 through the opening. The covering portion 12 at least partially overlaps with the opening surface of the shell 2. Along the thickness direction of the battery cover, the thickness of the embedded portion 11 is a, and the thickness of the covering portion 12 is b, satisfying a>b, 0.15≤b / a≤0.85.

[0023] Optionally, the value of b / a can be any value among 0.15, 0.2, 0.25, 0.28, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, or any value between any two of them.

[0024] The battery cover of this embodiment has a smaller thickness of the cover portion 12, and the heat generated by the welding of the battery cover and the shell 2 can be quickly dissipated through the cover portion 12, thereby improving the heat dissipation effect of the battery, thereby reducing the heat transferred to the interior of the battery, avoiding excessive internal temperature of the battery, and further avoiding damage to the battery cell 3; at the same time, the embedded portion 11 has a larger thickness, and the path for the heat generated by the welding of the battery cover and the shell 2 to be transferred to the interior of the battery is longer, further reducing the heat transferred to the interior of the battery.

[0025] It should be noted that if the value of b / a is too large, that is, the value of a is too small and / or the value of b is too large, when the value of a is too small, that is, the embedded portion 11 is too thin, there is a risk of welding through the embedded portion 11 during the tilt welding process, and the cover body 1 and the shell 2 are both made of steel. The welding of the battery cover and the shell 2 requires more heat, which will also increase the risk of the embedded portion 11 being welded through. At the same time, the heat generated by welding is more easily transferred to the inside of the battery and cause damage to the battery cell 3. When the value of b is too large, That is, the cover part 12 is too thick, resulting in a weakened heat dissipation capacity of the cover part 12, and the heat generated by welding cannot be dissipated in time, resulting in an increase in the heat transferred to the inside of the battery; if the value of b / a is too small, that is, the value of a is too large and / or the value of b is too small, when the value of a is too large, that is, the embedded part 11 is too thick, the embedded part 11 occupies too much space inside the shell 2, resulting in a reduction in the battery energy density; when the value of b is too small, that is, the cover part 12 is too thin, there is a risk of the cover part 12 being welded through during the welding process. Therefore, the value of the ratio b / a of the thickness a of the embedded part 11 and the thickness b of the cover part 12 is controlled to ensure the heat dissipation capacity of the battery cover and the energy density of the battery while ensuring the welding quality of the battery cover and the shell 2.

[0026] For further information, see Figure 4 The battery cover and the shell 2 are usually welded by tilting ( Figure 4 The housing 2 is connected to the covering portion 12 and the embedding portion 11 of the cover body 1. Figure 4If the thickness of the embedded portion 11 is too small, there is a risk of welding through the embedded portion 11 during the tilt welding process. In addition, in this embodiment, the housing 2 is made of steel, and welding the battery cover plate and the housing 2 requires more heat, which will increase the risk of welding through the embedded portion 11. Therefore, a>b, that is, the thickness of the embedded portion 11 is greater than the thickness of the cover portion 12, thereby ensuring that the embedded portion 11 has sufficient thickness, avoiding the embedded portion 11 being too thin and causing welding through during tilt welding, thereby avoiding problems such as electrolyte leakage in the battery due to welding through.

[0027] It is worth noting that the battery cover of this embodiment is used to block the opening of the steel shell 2, that is, the battery cover needs to be welded to the steel shell 2, and the cover body 1 is also made of steel. However, the steel cover body 1 and the steel shell 2 have poor thermal conductivity, and the melting point of steel is relatively high. The welding of the battery cover and the shell 2 will require more heat. If the heat cannot be dissipated in time at the welding point, it is easy to affect the structure of the battery cover and the shell 2. Therefore, in this embodiment, by providing a thinned cover portion 12, it is easier to dissipate the heat from the welding point in time, thereby improving the heat dissipation effect.

[0028] It should be noted that, in this embodiment, Figure 1 As shown, the main body structure further includes a connecting portion 13, the connecting portion 13 and the embedding portion 11 are stacked, and the covering portion 12 is arranged around the connecting portion 13. When the battery cover plate is assembled with the shell 2, the embedding portion 11 is inserted into the shell 2, the connecting portion 13 and the covering portion 12 are both located outside the shell 2, and the covering portion 12 at least partially overlaps with the opening surface of the shell 2.

[0029] It is worth noting that the opening surface refers to the end surface of the shell body where the opening is provided.

[0030] Furthermore, in this embodiment, the cover portion 12 is arranged around the circumference of the main body structure, so that the heat dissipation of the battery cover is more uniform, and excessive local heat concentration is avoided.

[0031] Of course, in other alternative embodiments, the covering portion 12 may also be arranged along the four sides of the main body structure but not around the perimeter (ie, partially around the main body structure), for example, the covering portion 12 may be arranged at both ends of the main body structure along the length direction.

[0032] In one embodiment, Figure 1 As shown, along the length direction of the battery cover, the distance between the edge of the cover portion 12 and the edge of the embedding portion 11 is e, which satisfies 0.05mm≤e≤0.8mm. That is, along the length direction of the battery cover, the width of the cover portion 12 is e.

[0033] It is worth noting that if the value of e is too large, the edge of the cover 12 is likely to extend out of the shell 2, causing the side of the battery cover to protrude from the shell 2, affecting the overall quality of the battery and the subsequent battery grouping; if the value of e is too small, the heat dissipation area of ​​the cover 12 is reduced, resulting in a reduction in the heat dissipation capacity of the cover 12, affecting the heat dissipation effect, and affecting the welding depth of the battery cover and the shell 2, that is, the depth of penetration is reduced, and in order to ensure the welding effect, the weld width needs to be increased, but the increase in the weld width will increase the risk of laser damage to the battery cell 3 during welding. Therefore, by controlling the value of e within an appropriate range, a sufficient heat dissipation area is achieved, while ensuring the welding reliability of the battery cover and the shell 2.

[0034] In one embodiment, the thickness a of the embedded portion 11 is in the range of 0.3 mm ≤ a ≤ 1 mm, and the thickness b of the cover portion 12 is in the range of 0.1 mm ≤ b ≤ 0.9 mm. In this way, the thickness of the embedded portion 11 and the thickness of the cover portion 12 are both reasonably selected, and the heat dissipation capacity of the battery cover and the energy density of the battery are guaranteed while the welding quality of the battery cover and the shell 2 is guaranteed.

[0035] In one embodiment, Figure 2 As shown, along the thickness direction of the battery cover, a groove 111 is provided on one side of the embedded portion 11 away from the covering portion 12, and the embedded portion 11 forms a remaining portion 112 around the groove 111. Along the length direction of the battery cover, the width of the remaining portion 112 is d, satisfying 0.2mm≤d≤1.5mm, 0.25≤b / a≤0.8.

[0036] By setting a groove 111 in the cover portion 12, the groove 111 is used as an air layer. The heat conductivity of air is relatively poor compared to metal, so the heat generated by the welding of the battery cover and the shell 2 is less likely to be transferred to the inside of the battery. In this way, the thickness of the embedded portion 11 can be relatively reduced, and the thickness of the cover portion 12 can be relatively increased. While ensuring that the heat generated by the welding of the battery cover and the shell 2 will not damage the battery cell 3, the occupation of the internal space of the shell 2 by the embedded portion 11 is reduced, the battery energy density is improved, and the cover portion 12 is further ensured not to be welded through. At the same time, the smaller the width of the remaining part 112, that is, the larger the opening range of the groove 111, the larger the volume of the air layer, the less likely the heat generated by the welding of the battery cover and the shell 2 is to be transferred to the inside of the battery. If the width of the remaining part 112 is too small, it is more likely to cause welding penetration during welding, and the structural strength of the cover body 1 will be affected. In addition, since the electrolyte needs to be injected into the battery, if the remaining part 112 is welded through, the risk of electrolyte leakage increases. Therefore, in this example, the value of the width d of the remaining portion 112 is limited, so as to reduce the thermal conductivity of the battery cover to the inside while ensuring the welding quality of the battery cover and the shell 2 and the structural strength of the battery cover.

[0037] It should be noted that the width of the remaining portion 112 at different positions can be the same or different, and can be specifically set according to actual needs, and it is only necessary to make the width of each position of the remaining portion 112 satisfy 0.2mm≤d≤1.5mm. For example, refer to Figure 2 The width of the remaining portion 112 located on the left side of the groove 111 and the width of the remaining portion 112 located on the right side of the groove 111 may be the same or different.

[0038] It is worth noting that, for the battery cover, the direction close to the housing 2 is the "inside", and the direction away from the housing 2 is the "outside". Figure 2 The outer side surface of the embedded portion 11 is connected to the inner side surface of the connecting portion 13 , the side of the embedded portion 11 away from the covering portion 12 is the inner side surface of the embedded portion 11 , and the groove 111 is opened outward from the inner side surface of the embedded portion 11 .

[0039] According to an embodiment of the present invention, on the other hand, a battery is provided, comprising:

[0040] A shell 2, the shell 2 is made of steel, and at least one end of the shell 2 has an opening;

[0041] The battery cover plate mentioned above blocks the opening and is welded to the housing 2 to form a weld mark 5, and the battery cover plate and the housing 2 are enclosed to form a receiving space;

[0042] The battery cell 3 is arranged in the accommodating space.

[0043] In one embodiment, Figure 5 As shown, the battery cell 3 includes a stacked positive electrode sheet, a separator and a negative electrode sheet. Along the thickness direction of the battery cover, the distance between the separator and a side of the embedding portion 11 away from the covering portion 12 is f, satisfying 0.5mm≤f≤8mm.

[0044] It is worth noting that if the value of f is too small, the distance between the cover body 1 and the battery cell 3 is too close, the heat generated by the welding of the battery cover and the shell 2 is easily transferred to the battery cell 3, and the diaphragm shrinks when heated, which can easily cause a short circuit between the positive and negative poles; if the value of f is too large, the distance between the cover body 1 and the battery cell 3 is too large, resulting in a waste of internal space in the battery and affecting the energy density of the battery.

[0045] It should be noted that the size of the diaphragm needs to be larger than the size of the positive and negative electrodes to completely isolate the positive and negative electrodes and avoid short circuits between the positive and negative electrodes. Therefore, the edge of the diaphragm is closer to the embedded portion 11 than the edge of the positive and negative electrodes.

[0046] Further, such as Figure 5As shown, a pole assembly 4 is arranged on the cover body 1, and the battery cell 3 includes a battery cell body 31 and a pole ear 32. The pole ear 32 is led out from the battery cell body 31, and the pole ear 32 is arranged on the side of the battery cell body 31 facing the cover body 1. The pole ear 32 is electrically connected to the pole assembly 4, and meets 0.5mm≤f≤6mm. With such a setting, the heat generated by the welding of the battery cover and the shell 2 may be assisted by the pole assembly 4 and the pole ear 32 to dissipate heat, reducing the heat transferred to the battery cell 3. Therefore, the distance between the cover body 1 and the battery cell 3 can be set smaller, further improving the energy density of the battery.

[0047] It is worth noting that the pole assembly 4 is used as a current output pole, and is used to be electrically connected to the pole ear 32 of the battery cell 3, and is also electrically connected to the external bus bar to achieve current transmission. The pole assembly 4 can be a pole body, and the pole ear 32 can be directly electrically connected to the pole body; the pole assembly 4 can also be a pole body and an adapter, the pole ear 32 and the adapter are welded, and the adapter is welded to the pole body, that is, the pole ear 32 and the pole body are indirectly electrically connected through the adapter.

[0048] In one embodiment, Figure 5 As shown, the tabs 32 include a positive tab 32 and a negative tab 32, which are led out from the same side of the battery body 31, satisfying 0.5mm≤f≤5mm. In this way, both the positive tab 32 and the negative tab 32 can be used for heat dissipation, so the distance between the cover body 1 and the battery cell 3 can be set smaller to further improve the energy density of the battery.

[0049] It should be noted that, in other alternative implementations, such as Figure 6 As shown, the cover body 1 is provided with a pole assembly 4, the battery cell 3 includes a battery body 31 and a pole ear 32, the pole ear 32 is led out in the length direction of the battery body 31, and the pole ear 32 is electrically connected to the pole assembly 4, satisfying 1mm≤f≤7mm. Figure 6 As shown, the pole ear 32 is led out from both ends of the length direction of the battery cell body 31, that is, the pole ear 32 is arranged on the side of the battery cell body 31 facing the side wall 21 of the shell 2, and the pole column assembly 4 is arranged on the cover body 1. The pole ear 32 is connected to the pole column assembly 4 through the adapter, resulting in a long heat dissipation path and poor heat dissipation effect. Therefore, it is necessary to appropriately increase the distance between the cover body 1 and the battery cell 3 to reduce heat transfer.

[0050] It is worth noting that the length direction of the battery cell body 31 is the length direction of the battery cover.

[0051] In one embodiment, the pole assembly 4 includes a pole body, and the end surface area of ​​the pole body away from the battery cell 3 is S, and S≥100mm 2, 0.28≤b / a≤0.85. The heat generated by the battery cell 3 can be dissipated through the pole. When the end surface area of ​​the pole is larger, the heat dissipation area increases, which is more conducive to heat dissipation. Therefore, the value range of b / a can be further controlled to further ensure the welding quality of the battery cover and the shell 2, and at the same time, the energy density of the battery can be further improved.

[0052] In one embodiment, Figure 3 and Figure 4 As shown, the shell 2 includes a side wall 21, which is welded to the cover body 1, and the wall thickness of the side wall 21 is c, which satisfies c≥0.2mm and 0.2≤b / a≤0.8. The thickness of the side wall 21 is not less than 0.2mm, which can reduce the risk of deformation of the shell 2 due to heat; however, the thicker the shell 2, the more heat is required for welding the battery cover and the shell 2, and the greater the risk of damage to the battery cell 3; therefore, by further controlling the value of b / a within the range of 0.2 to 0.8, the heat dissipation effect is further improved, the heat transferred to the inside of the battery is reduced, and damage to the battery cell 3 is avoided.

[0053] In one embodiment, Figure 3 and Figure 7 As shown, the cover body 1 serves as the bottom wall of the battery, and the shell 2 includes a top wall 22 arranged opposite to the cover body 1 , and the top wall 22 is provided with a pole assembly 4 , satisfying 0.25≤b / a≤0.75.

[0054] It is worth noting that the heat generated by the welding of the battery cover plate and the shell 2 cannot be dissipated through the pole ear 32. Therefore, by further limiting the value range of b / a, the heat dissipation effect is further improved, the heat transferred to the inside of the battery is reduced, and the battery cell is avoided from being damaged. In addition, the steel shell 2 is usually open at both ends. When the battery cover plate of the present embodiment corresponds to the bottom opening of the shell 2, the battery cover plate serves as the bottom wall of the battery, and the battery cover plate needs to be used to support the battery cell. Therefore, the battery cover plate and the shell 2 require greater welding strength, and more heat will be required during the welding process. Therefore, by further controlling the value of b / a within the range of 0.25 to 0.75, when the battery cover plate of the present embodiment is used as the bottom wall of the battery, it can not only ensure the welding strength with the shell 2, but also improve the heat dissipation effect.

[0055] It can be understood that the bottom wall of the battery is the side close to the bottom of the battery box when the battery is installed in the battery pack box.

[0056] For further information, see Figure 3 The side opposite to the bottom wall of the battery is the top wall 22 of the battery. In this embodiment, the top wall 22 of the battery is also a battery cover. Figure 3As shown, both opposite ends of the housing 2 have openings, and two battery covers are provided, one of which is provided corresponding to the bottom opening of the housing 2 to serve as the bottom wall of the battery, and the other is provided corresponding to the top opening of the housing 2 to serve as the top wall 22 of the battery. Of course, in other alternative embodiments, such as Figure 7 As shown, the top wall 22 of the battery may also adopt other structures capable of sealing the opening, such as a flat plate structure.

[0057] In one embodiment, Figure 8 As shown, the value range of the weld width g of the weld mark 5 is 0.1 mm ≤ g ≤ 1.5 mm, and the value range of the weld depth h of the weld mark 5 is 0.1 mm ≤ h ≤ 1.5 mm. This arrangement ensures the connection strength between the battery cover and the housing 2.

[0058] Furthermore, the weld width of the weld mark 5 forms a first weld width i corresponding to the embedded portion 11 and forms a second weld width j corresponding to the covering portion 12, i>j.

[0059] In one embodiment, the battery cell 3 includes a plurality of stacked electrode sheets, the thickness of a single electrode sheet is m, the number of electrode sheets is n, and m×n≥10mm, 0.2≤b / a≤0.65. The greater the thickness of the single electrode sheet and / or the more electrode sheets there are, the more heat the battery cell 3 generates. Therefore, by further controlling the value of b / a within the range of 0.2 to 0.65, the heat dissipation effect of the battery cover is further improved.

[0060] Furthermore, the battery cell 3 also includes a diaphragm, which is stacked between two adjacent layers of pole pieces. Heat is generated during the battery charging and discharging process, and the diaphragm is easily shrunk and deformed by the heat, resulting in a positive and negative short circuit in the battery. In the battery of this embodiment, the value of b / a is further controlled, and the heat generated during the battery charging and discharging process is easy to be quickly dissipated through the cover 12, thereby improving the heat dissipation capacity of the battery itself and ensuring the safety of the battery.

[0061] It should be noted that when the cover body 1 and the shell 2 are both made of stainless steel, 0.15≤b / a≤0.85 is satisfied. When the cover body 1 and the shell 2 are both made of nickel-plated steel, 0.15≤b / a≤0.7 is satisfied. Different steels have different melting points when welded. The higher the melting point, the greater the heat required for welding the battery cover and the shell 2. Therefore, for different steel materials, the range of b / a is further limited to achieve the heat dissipation effect and ensure the welding reliability of the cover body 1 and the shell 2.

[0062] It should be further explained that stainless steel is an alloy material, the main components of which include iron, chromium, nickel and a small amount of other elements. Chromium is the basic element that makes stainless steel corrosion-resistant, making it anti-oxidation and anti-corrosion, able to resist the erosion of most chemical media, and having a long service life. The corrosion resistance of stainless steel depends on the alloying elements contained in the steel, and it has good mechanical properties and wear resistance. The melting point of stainless steel ranges from 1100℃ to 1510℃. Nickel-plated steel is a metal product with a base material of ordinary steel, and a layer of nickel is plated on the surface through an electroplating process. The melting point of nickel-plated steel ranges from 1300℃ to 1510℃.

[0063] It is worth noting that the separator is arranged between the positive electrode sheet and the negative electrode sheet, and the positive electrode sheet, the negative electrode sheet and the separator are wound or stacked to form a battery cell 3; the positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer, and the negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer. There is no special restriction on the positive electrode current collector, as long as it has conductivity and does not cause adverse chemical changes in the battery, and can use, for example: stainless steel, aluminum, nickel, titanium, fired carbon, or aluminum or stainless steel with a surface treatment of carbon, nickel, titanium, silver, etc.; the negative electrode current collector can be copper, stainless steel, nickel, titanium, etc., and a composite current collector can also be used. The composite current collector refers to a polymer layer in the middle, and metal layers are arranged on the opposite sides of the polymer layer. The metal layer can be made of copper, stainless steel, nickel, titanium, etc.; in a specific embodiment, the positive electrode current collector can be aluminum, and the negative electrode current collector can be copper. The positive electrode active material layer includes positive electrode active materials, which include nickel-cobalt-manganese ternary materials, lithium iron phosphate materials, lithium manganese iron phosphate materials, etc.; the negative electrode active material layer includes negative electrode active materials, which include artificial graphite, natural graphite, silicon-based materials, etc.

[0064] According to an embodiment of the present invention, in yet another aspect, a battery pack is provided, comprising the above-mentioned battery.

[0065] Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A battery, characterized in that: include: A shell (2), the shell (2) being made of steel, and at least one end of the shell (2) having an opening; A battery cover plate, which blocks an opening of a steel shell (2) and is welded to the shell (2) to form a weld mark (5); the battery cover plate and the shell (2) are enclosed to form a receiving space; the battery cover plate comprises a cover plate body (1), the cover plate body (1) is made of steel; the shell (2) comprises a side wall (21), the side wall (21) is welded to the cover plate body (1); the cover plate body (1) comprises a body structure and a cover portion (12); the cover portion (12) is arranged around the body structure; the body structure comprises an embedded portion (11), the embedded portion (11) is used to extend into the shell (2) from the opening; the cover portion (12) at least partially overlaps with the opening surface of the shell (2); along the thickness direction of the battery cover plate, the thickness of the embedded portion (11) is a, and the thickness of the cover portion (12) is b, satisfying a>b, 0.15≤b / a≤0.85; A battery cell (3) is arranged in the accommodation space; A pole assembly (4) is arranged on the cover plate body (1); the battery cell (3) comprises a battery cell body (31) and a pole lug (32); the pole lug (32) is led out in the length direction of the battery cell body (31); and the pole lug (32) is electrically connected to the pole assembly (4).

2. The battery according to claim 1, characterized in that Along the length direction of the battery cover, the distance between the edge of the covering portion (12) and the edge of the embedding portion (11) is e, satisfying 0.05mm≤e≤0.8mm.

3. The battery according to claim 1 or 2, characterized in that: The covering portion (12) is arranged around the circumference of the main body structure.

4. The battery according to claim 1 or 2, characterized in that: The thickness a of the embedded portion (11) has a value range of 0.3 mm ≤ a ≤ 1 mm, and the thickness b of the covering portion (12) has a value range of 0.1 mm ≤ b ≤ 0.9 mm.

5. The battery according to claim 1 or 2, characterized in that: Along the thickness direction of the battery cover, a groove (111) is provided on a side of the embedded portion (11) away from the covering portion (12), and the embedded portion (11) forms a remaining portion (112) around the groove (111). Along the length direction of the battery cover, the width of the remaining portion (112) is d, satisfying 0.2mm≤d≤1.5mm and 0.25≤b / a≤0.

8.

6. The battery according to claim 1 or 2, characterized in that: The battery cell (3) comprises a positive electrode sheet, a separator and a negative electrode sheet which are stacked in layers. Along the thickness direction of the battery cover, the distance between the separator and a side of the embedded portion (11) away from the covering portion (12) is f, satisfying 1mm≤f≤7mm.

7. The battery according to claim 1 or 2, characterized in that: The pole assembly (4) comprises a pole body, the end surface area of ​​the pole body on the side away from the battery core (3) is S, and S≥100mm 2 , 0.28≤b / a≤0.

85.

8. The battery according to claim 1 or 2, characterized in that: The cover plate body (1) and the shell (2) are both made of stainless steel, satisfying 0.15≤b / a≤0.85; or, The cover plate body (1) and the shell (2) are both made of nickel-plated steel, satisfying 0.15≤b / a≤0.

7.

9. The battery according to claim 1 or 2, characterized in that: The wall thickness of the side wall (21) is c, satisfying c≥0.2 mm, 0.2≤b / a≤0.

8.

10. The battery according to claim 1 or 2, characterized in that: The value range of the weld width g of the weld mark (5) is 0.1 mm ≤ g ≤ 1.5 mm, and the value range of the weld depth h of the weld mark (5) is 0.1 mm ≤ h ≤ 1.5 mm.

11. The battery according to claim 10, characterized in that The weld width of the weld mark (5) forms a first weld width i corresponding to the embedded portion (11), and forms a second weld width j corresponding to the covering portion (12), satisfying i>j.

12. The battery according to claim 1 or 2, characterized in that: The battery cell (3) comprises a plurality of stacked pole sheets, the thickness of a single pole sheet is m, the number of pole sheet layers is n, and m×n≥10 mm, 0.2≤b / a≤0.65 is satisfied.

13. A battery pack, characterized in that: A battery comprising the battery according to any one of claims 1 to 12.

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