battery

Abstract

The application relates to the technical field of batteries and discloses a battery, which comprises a shell, an electric core and an electrode terminal, the shell comprises a titanium element, the electrode terminal is electrically connected with the electric core, at least part of the electrode terminal is welded with the shell to form a welding mark, the electrode terminal is electrically connected with the electric core, the peeling strength between the shell and the electrode terminal is a, the thickness of the shell is T1, the thickness of the electrode terminal welded with the shell is T2, and the content of the titanium element in the shell is c, wherein c >= 90%, b = |T1 / T2-1|, and 0.01 <= b * c / a <= 5. By controlling b * c / a in the above range, the connection strength between the shell and the electrode terminal is improved, the shell and the electrode terminal are prevented from being separated, the overcurrent capacity between the shell and the electrode terminal is ensured, the temperature rise caused by the resistance is reduced, the welding heat is prevented from being too large to damage the electric core and cause the diaphragm to shrink and increase the risk of positive and negative electrode short circuit, and the safety performance of the battery is improved.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and more specifically to batteries. Background Technology

[0002] A rechargeable battery is a type of battery that can recover its performance after being discharged through a charging process. Rechargeable batteries are widely used in consumer electronics, electric vehicles, energy storage systems, and other fields.

[0003] Battery lightweighting is a crucial direction in current battery technology development, particularly in fields such as electric vehicles, portable electronic devices, and aerospace. With increasing demands for energy efficiency and portability, reducing battery weight while maintaining or increasing its energy density has become a research hotspot.

[0004] The battery includes a casing and a cell housed within the casing. The casing is made of titanium, and can be referred to as a titanium casing. The titanium casing enables lightweighting of the main body and can be used in flying cars to increase flight speed. However, when the titanium casing is used as an electrode output terminal of the battery, it has been found that the electrical connection between the titanium casing and the cell is prone to failure when the battery is discharging or subjected to vibration, affecting the current transmission between the cell and the titanium casing. Summary of the Invention

[0005] In view of this, the present invention provides a battery to solve the problem in the prior art where the electrical connection between the titanium casing and the battery cell is prone to failure, affecting the current transmission between the battery cell and the titanium casing.

[0006] This invention provides a battery comprising: a casing, a battery cell, and electrode terminals. The battery cell is disposed inside the casing. The casing includes titanium. The electrode terminals are electrically connected to the battery cell. At least a portion of the electrode terminals is welded to the casing to form a solder mark. The peel strength between the casing and the electrode terminals is 'a' (in N). The thickness of the casing is 'T1' (in mm). The thickness of the electrode terminals welded to the casing is 'T2' (in mm). The titanium content in the casing is 'c', where c ≥ 90%, b = |T1 / T2 - 1|, and 0.01 ≤ b × c / a ≤ 5.

[0007] Beneficial effects: By controlling b×c / a within the above range, the connection strength between the casing and the electrode terminals is improved, preventing separation between the casing and the electrode terminals, thereby ensuring the overcurrent capacity between the casing and the electrode terminals and reducing the temperature rise caused by the resistance between the casing and the electrode terminals; at the same time, it avoids excessive welding heat from damaging the cell, causing the separator to shrink and increasing the risk of short circuit between the positive and negative electrodes, thus improving the safety performance of the battery. Attached Figure Description

[0008] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0009] Figure 1 This is a perspective view of a battery according to an embodiment of the present invention;

[0010] Figure 2 for Figure 1 A top view of the battery shown;

[0011] Figure 3 for Figure 2 A cross-sectional view along the AA direction;

[0012] Figure 4 for Figure 3 A magnified view of part B in the image;

[0013] Figure 5 for Figure 4 A schematic diagram showing the dimensions of the structure is provided.

[0014] Figure 6 This is a partial cross-sectional view of another battery according to an embodiment of the present invention;

[0015] Figure 7 This is a schematic diagram of the first end face and solder mark in an embodiment of the present invention;

[0016] Figure 8 This is a schematic diagram of the structure of the tab portion according to an embodiment of the present invention;

[0017] Figure 9 This is a schematic diagram of the structure of the tabs spaced apart on the winding layer (before winding) according to an embodiment of the present invention;

[0018] Figure 10 This is a schematic diagram of the first end face and the current collector in an embodiment of the present invention;

[0019] Figure 11 This is a schematic diagram of the current collector and solder mark according to an embodiment of the present invention;

[0020] Figure 12 This is a schematic diagram of the structure of the positive and negative electrode tabs located at opposite ends of the battery cell according to an embodiment of the present invention;

[0021] Figure 13 This is a schematic diagram of the stacked structure of the positive electrode, separator, and negative electrode in an embodiment of the present invention.

[0022] Explanation of reference numerals in the attached figures:

[0023] 1. Shell; 11. Shell body; 12. End wall; 121. Recess; 13. First end face; 14. End cap; 2. Cell; 21. Positive electrode plate; 22. Negative electrode plate; 23. Diaphragm; 3. Electrode terminal; 31. Tab; 311. Tab body; 312. Positive electrode tab; 313. Negative electrode tab; 32. Current collector; 4. Solder mark; 5. Insulating component. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] The following is combined with Figures 1 to 13 The following describes embodiments of the present invention.

[0026] According to an embodiment of the present invention, a battery is provided, comprising: a housing 1, a battery cell 2, and electrode terminals 3. The battery cell 2 is disposed inside the housing 1. The housing 1 includes titanium. The electrode terminals 3 are electrically connected to the battery cell 2. At least a portion of the electrode terminals 3 is welded to the housing 1 to form a solder mark 4. The peel strength between the housing 1 and the electrode terminals 3 is a (in N). The thickness of the housing 1 is T1 (in mm). The thickness of the electrode terminals 3 welded to the housing 1 is T2 (in mm). The titanium content in the housing 1 is c, wherein c ≥ 90%, b = |T1 / T2 - 1|, and 0.01 ≤ b × c / a ≤ 5.

[0027] By controlling b×c / a within the above-mentioned range, the connection strength between the casing 1 and the electrode terminal 3 is improved, preventing the casing 1 and the electrode terminal 3 from separating. This ensures the overcurrent capacity between the casing 1 and the electrode terminal 3 and reduces the temperature rise caused by the resistance between the casing 1 and the electrode terminal 3. At the same time, it avoids excessive welding heat from damaging the cell 2 and causing the separator 23 to shrink, increasing the risk of short circuit between the positive and negative electrodes, thus improving the safety performance of the battery.

[0028] It is worth noting that if the value of b×c / a is too large, the connection strength between electrode terminal 3 and shell 1 will be too low, leading to an excessive risk of connection failure between electrode terminal 3 and shell 1. This will affect the current transmission between electrode terminal 3 and shell 1, increase the current transmission impedance, and increase heat generation during current transmission, thus affecting the battery's safety performance. If the value of b×c / a is too small, the heat required for welding electrode terminal 3 and shell 1 will increase, which may easily damage cell 2 and cause the separator 23 to shrink, increasing the risk of short circuit between the positive and negative electrodes.

[0029] Further preferred, the value of b×c / a satisfies 0.06≤b×c / a≤1.2.

[0030] Optionally, b×c / a can take any value from 0.01, 0.06, 0.1, 0.5, 0.8, 1, 1.2, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5 or a value between any two values.

[0031] Where a is the value when the unit is N, and T1 and T2 are the values ​​when the unit is mm.

[0032] Specifically, in one embodiment, the peel strength α between the housing 1 and the electrode terminal 3 satisfies 100N ≤ α ≤ 600N. This configuration avoids connection failure between the electrode terminal 3 and the housing 1, while also preventing excessive welding heat that could damage the battery cell 2 and create a short circuit risk.

[0033] It is worth noting that if the value of 'a' is too small, the connection strength between electrode terminal 3 and shell 1 will be too low, leading to an excessive risk of connection failure between electrode terminal 3 and shell 1. This will affect the current transmission between electrode terminal 3 and shell 1, increase the current transmission impedance, and increase heat generation during current transmission, thus affecting the battery's safety performance. If the value of 'a' is too large, the heat required for welding electrode terminal 3 and shell 1 will increase, which may easily damage cell 2 and cause the separator 23 to shrink, increasing the risk of short circuit between the positive and negative electrodes.

[0034] More preferably, the peel strength α between the housing 1 and the electrode terminal 3 satisfies 200N≤α≤500N.

[0035] Optionally, the value of 'a' can be any one of 100N, 150N, 200N, 250N, 300N, 350N, 400N, 450N, 500N, 550N, or 600N, or a value between any two of these values.

[0036] This application does not limit the test method for peel strength. For example, the shell 1 and the electrode terminal 3 welded to the shell 1 can be clamped by a tensile testing machine clamp, and the tensile test can be performed vertically and the force data when the shell is pulled off can be recorded.

[0037] Specifically, in one embodiment, the thickness T1 of the housing 1 and the thickness T2 of the electrode terminal 3 welded to the housing 1 satisfy 0.05≤b=|T1 / T2-1|≤6.5. This setting ensures the weld penetration depth between the housing 1 and the electrode terminal 3, thereby ensuring the welding reliability of the housing 1 and the electrode terminal 3, reducing the risk of connection failure between the housing 1 and the electrode terminal 3, and at the same time avoiding damage to the battery cell 2 and the risk of short circuit caused by excessive welding heat.

[0038] It is worth noting that if the value of b is too large, that is, if the value of |T1 / T2-1| is too large, it will lead to a large difference between the thickness of the housing 1 and the thickness of the electrode terminal 3 welded to the housing 1. When welding the housing 1 and the electrode terminal 3, the penetration depth of the weld 4 will be limited by the smaller of the thicknesses of the housing 1 and the electrode terminal 3 welded to the housing 1, resulting in lower welding strength and a higher risk of connection failure. If the value of b is too small, the heat required to weld the housing 1 and the electrode terminal 3 will increase, which may easily damage the cell 2 and cause the diaphragm 23 to shrink, increasing the risk of short circuit between the positive and negative electrodes.

[0039] Further preferred, the value of b satisfies 0.25≤b≤3.

[0040] Optionally, the value of b can be any one of the following: 0.05, 0.1, 0.2, 0.25, 0.3, 0.4, 0.45, 0.5, 0.8, 1, 1.2, 1.5, 1.8, 2, 2.2, 2.5, 2.8, 3, 3.5, 3.6, 3.8, 4, 4.5, 5, 5.5, 6, 6.5, or a value between any two of these values.

[0041] Specifically, in one embodiment, such as Figure 5 As shown, the thickness T1 of the housing 1 satisfies 0.3mm≤T1≤1.5mm. This setting ensures the connection strength between the housing 1 and the electrode terminal 3 while avoiding excessive welding heat that could damage the battery cell 2 and cause a short circuit.

[0042] It is worth noting that if the value of T1 is too small, the structural strength of the housing 1 will be too low, resulting in a weak connection between the housing 1 and the electrode terminal 3, which will increase the risk of connection failure between the housing 1 and the electrode terminal 3. If the value of T1 is too large, the heat required for the solder mark 4 to penetrate the housing 1 and connect with the electrode terminal 3 during the welding process will be too high, which may easily damage the cell 2 and cause the diaphragm 23 to shrink, increasing the risk of short circuit between the positive and negative electrodes.

[0043] Optionally, T1 can be any value from 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, or a value between any two of these values.

[0044] Specifically, in one embodiment, such as Figure 5 and Figure 6 As shown, the thickness T2 of the electrode terminal 3 welded to the housing 1 satisfies 0.09mm≤T2≤2mm. This configuration ensures both the connection strength between the housing 1 and the electrode terminal 3 and the battery energy density.

[0045] It is worth noting that if the value of T2 is too small, the electrode terminal 3 welded to the casing 1 will have too little space to accommodate the thickness of the solder mark 4, resulting in a low connection strength between the casing 1 and the electrode terminal 3, which increases the risk of connection failure. If the value of T2 is too large, the electrode terminal 3 will occupy too much space in the battery, which may affect the energy density of the battery.

[0046] Optionally, T2 can be any value from 0.09mm, 0.1mm, 0.3mm, 0.35mm, 0.4mm, 0.5mm, 0.55mm, 0.6mm, 0.65mm, 0.7mm, 0.75mm, 0.8mm, 1mm, 1.2mm, 1.5mm, 1.8mm, 2mm, or a value between any two of these values.

[0047] Specifically, in one embodiment, the titanium content *c* in the shell 1 satisfies 90% ≤ *c* ≤ 99.99%. It is worth noting that *c* refers to the ratio of the titanium content in the shell 1 to the total content of all elements.

[0048] Further preferably, the value of c satisfies 97% ≤ c ≤ 99.99%.

[0049] Optionally, c can take any value from 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.99%, or a value between any two values.

[0050] In one embodiment, such as Figures 1 to 4 As shown, the housing 1 includes a housing body 11 and an end wall 12 connected to one end of the housing body 11. A recess 121 is provided on the end wall 12. The electrode terminal 3 includes a tab 31 and a current collector 32. The tab 31 is disposed between the battery cell 2 and the current collector 32. The current collector 32 is welded to the housing 1 to form a solder mark 4. The solder mark 4 is located in the recess 121. The value of b is within the range of 0.1≤b≤2.8.

[0051] It is worth noting that by partially thinning the end wall 12 along its thickness direction to form a recess 121, and then welding the end wall 12 (i.e., the remaining portion after thinning) and the current collector 32 at the location of the recess 121, it is easier to penetrate the end wall 12 and weld it to the current collector 32 during welding. This improves the welding quality between the end wall 12 and the current collector 32, enhances the welding reliability between the housing 1 and the current collector 32, and thus improves the current transmission capability between the housing 1 and the current collector 32. Therefore, in this embodiment, the value of b can be further controlled to further reduce the heat required for welding the housing 1 and the current collector 32, thereby further avoiding damage to the battery cell 2 and the risk of short circuit.

[0052] It should be noted that the end wall 12 can be integrally formed with the shell body 11, or it can be independently set with the shell body 11 and then connected by welding or other means (in this case, the end wall 12 is the end cap 14).

[0053] In one embodiment, such as Figure 5 As shown, the remaining thickness of the housing 1 in the recess 121 is H, which satisfies 0.6mm≤H≤0.9mm. This design improves the welding quality between the housing 1 and the manifold 32 while ensuring the structural strength of the housing 1.

[0054] It is worth noting that if the value of H is too large, the improvement effect on the penetration of the weld mark 4 into the housing 1 during the welding of the housing 1 and the collector plate 32 will not be significant, and therefore the improvement effect on the welding reliability between the housing 1 and the collector plate 32 will not be significant. If the value of H is too small, it may easily affect the structural strength of the housing 1.

[0055] Optionally, H can be any value from 0.6mm, 0.65mm, 0.7mm, 0.75mm, 0.8mm, 0.85mm, 0.9mm, or a value between any two of these values.

[0056] In one embodiment, such as Figure 5 As shown, the width of the recess 121 is W, satisfying 1.4mm≤W≤2.5mm. This design improves the welding strength between the housing 1 and the manifold 32 while ensuring the structural strength of the housing 1.

[0057] It is worth noting that if the value of W is too small, the area of ​​the housing 1 used for welding with the collector plate 32 will be too small, resulting in a limited welding area for the weld mark 4, which will affect the welding strength between the housing 1 and the collector plate 32 and increase the risk of connection failure. If the value of W is too large, the opening range of the recess 121 will be too large, resulting in excessive weakening of the structural strength of the housing 1 and easily affecting the structural strength of the housing 1.

[0058] Optionally, W can be any value from 1.4mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm, 2mm, 2.1mm, 2.2mm, 2.3mm, 2.4mm, 2.5mm, or a value between any two of these values.

[0059] In one embodiment, the current collector 32 comprises copper, and the value of b is in the range of 0.1 ≤ b ≤ 2. It should be noted that the melting point difference between titanium and copper is relatively small, facilitating welding. Furthermore, copper has a higher thermal conductivity than aluminum, enabling rapid heat conduction and helping to maintain temperature uniformity in the welded area, reducing the risk of localized overheating. Therefore, by further controlling b within the aforementioned range, the connection strength between the housing 1 and the electrode terminals 3 is ensured, preventing connection failure that could lead to current inrush, thereby guaranteeing the current-carrying capacity between the housing 1 and the electrode terminals 3, reducing temperature rise caused by resistance, and contributing to improved battery safety performance.

[0060] In another embodiment, such as Figure 6 As shown, electrode terminal 3 includes a tab portion 31. The housing 1 is welded to the tab portion 31 to form a solder mark 4. The tab portion 31 includes a plurality of stacked tab pieces 311, and the value of b satisfies 0.05≤b≤4. That is, directly welding the plurality of tab pieces 311 to the housing 1 will reduce the welding effect between the tab portion 31 and the housing 1, thereby reducing the reliability of the welding between the electrode terminal 3 and the housing 1 and making it easier for the connection between the electrode terminal 3 and the housing 1 to fail. Therefore, by further limiting the value of b, the welding strength between the housing 1 and the electrode terminal 3 is further improved, and the risk of connection failure between the housing 1 and the electrode terminal 3 is reduced.

[0061] Specifically, such as Figure 5 and Figure 6 As shown, the thickness of the current collector 32 is f, satisfying 0.35mm≤f≤1mm; the thickness of the electrode tab 31 is g, satisfying 0.09mm≤g≤2mm. This configuration ensures both the connection strength between the housing 1 and the electrode terminal 3 and the battery energy density.

[0062] It is worth noting that if the values ​​of f and g are too small, the current collector 32 or the tab 31 will be unable to accommodate the thickness of the solder mark 4, resulting in a low connection strength between the housing 1 and the electrode terminal 3, which increases the risk of connection failure between the housing 1 and the electrode terminal 3. If the values ​​of f and g are too large, the current collector 32 or the tab 31 will occupy too much space in the battery, which may affect the energy density of the battery.

[0063] It should be noted that you should refer to [link / reference]. Figure 5When electrode terminal 3 includes tab 31 and current collector 32, cell 2 is connected to tab 31, tab 31 is connected to current collector 32, and current collector 32 is welded to housing 1, then T2 = f. Please refer to [link / reference]. Figure 6 When the electrode terminal 3 only includes the tab 31, the battery cell 2 and the tab 31 are connected, and the tab 31 is welded to the housing 1, then T2 = g.

[0064] In one embodiment, such as Figure 5 As shown, the penetration depth of solder joint 4 is d, which satisfies 0.08mm ≤ d ≤ 0.3mm; the penetration width of solder joint 4 is e, which satisfies 1mm ≤ e ≤ 2.5mm. Figure 7 As shown, the solder mark 4 is disposed on the first end face 13 of the housing 1. The area of ​​the first end face 13 is S, and the area of ​​the orthographic projection of the solder mark 4 on the first end face 13 is S1. The values ​​of S and S1 satisfy 0.0048≤S1 / S≤0.008. This arrangement ensures the welding strength between the housing 1 and the electrode terminal 3 while avoiding excessive welding heat that could damage the battery cell 2 and cause a short circuit risk.

[0065] It is worth noting that if the values ​​of d, e, and S1 / S are too small, the welding strength between the housing 1 and the electrode terminal 3 will be low, the connection reliability between the housing 1 and the electrode terminal 3 will be poor, and the risk of connection failure between the housing 1 and the electrode terminal 3 will increase. If the values ​​of d, e, and S1 / S are too large, the heat required during welding will increase, which will increase the risk of damage to the battery cell 2 and short circuit.

[0066] Optionally, d can be any value from 0.08mm, 0.1mm, 0.12mm, 0.15mm, 0.18mm, 0.2mm, 0.22mm, 0.25mm, 0.28mm, 0.3mm, or a value between any two values.

[0067] Optionally, the value of e can be any one of 1mm, 1.2mm, 1.5mm, 1.8mm, 2mm, 2.2mm, 2.5mm, or a value between any two of these values.

[0068] Optionally, the value of S1 / S can be any one of 0.0048, 0.005, 0.0052, 0.0055, 0.0058, 0.006, 0.0062, 0.0065, 0.0068, 0.007, 0.0072, 0.0075, 0.0078, or 0.008, or a value between any two of these values.

[0069] In one embodiment, such as Figure 8As shown, the battery cell 2 is cylindrical and includes several wound layers stacked radially. The electrode portion 31 includes several electrode tabs 311 stacked. The wound layers are connected to at least one electrode tab 311. The electrode portion 31 has a first point and a second point arranged radially at intervals. The thickness of the electrode portion 31 at the first point is different from the thickness of the electrode portion 31 at the second point. The value of b satisfies 0.05≤b≤4.

[0070] It is worth noting that after the battery cell 2 is wound into shape, several tabs 311 are led out from the end face of the battery cell 2. Then, the tabs 311 need to be folded towards the end face of the battery cell 2, so that they are stacked on the end face of the battery cell 2. At this time, the tabs 31 have different thicknesses at different radial positions (here, "thickness" refers to the dimension along the axial direction of the battery). Because the thickness of the tabs 31 is inconsistent, the welding effect between the tabs 31 and the housing 1 is reduced, increasing the risk of connection failure between the tabs 31 and the housing 1. Therefore, by further controlling the value of b, the welding strength between the housing 1 and the tabs 31 is further improved, reducing the risk of connection failure between the housing 1 and the electrode terminals 3.

[0071] It should be further explained that the tab body 311 connected to the winding layer near the winding center is folded away from the winding center, and the tab body 311 connected to the winding layer away from the winding center is folded away from the winding center.

[0072] Furthermore, in one embodiment, such as Figure 8 As shown, the maximum thickness of the tab 31 is h1, and the minimum thickness of the tab 31 is h2, where h1-h2≤1.75mm. This design avoids excessive thickness differences at different locations of the tab 31, thereby ensuring the welding effect between the tab 31 and the housing 1 and reducing the risk of connection failure between the tab 31 and the housing 1.

[0073] Furthermore, in one embodiment, at the location where the tab portion 31 has the maximum thickness, the number of layers of the tab body 311 is not less than 10, and the value of b satisfies the range of 0.05 ≤ b ≤ 3.5. It is worth noting that the more layers of the tab body 311 are stacked, the worse the welding effect between the tab portion 31 and the housing 1, leading to an increased risk of connection failure between the tab portion 31 and the housing 1. Therefore, by further controlling the value of b, the welding strength between the housing 1 and the tab portion 31 is further improved, reducing the risk of connection failure between the housing 1 and the electrode terminal 3.

[0074] In one embodiment, such as Figure 9As shown, each winding layer has several tabs 311 spaced circumferentially, and the value of b satisfies 0.05≤b≤3. After the tabs 311 are folded onto the end face of the cell 2, the poor continuity between the tabs 311 results in poor welding continuity when welding the tabs 31 and the housing 1, leading to a lower welding effect and an increased risk of connection failure between the tabs 31 and the housing 1. Therefore, by further controlling the value of b, the welding strength between the housing 1 and the tabs 31 can be further improved, reducing the risk of connection failure between the housing 1 and the electrode terminal 3.

[0075] Furthermore, in one embodiment, such as Figure 9 As shown, the distance between adjacent tab pieces 311 on a single winding layer is i, satisfying 0.01mm≤i≤0.05mm. This setting improves the welding effect between the tab piece 31 and the housing 1 while preventing the tab piece 311 from being too large and causing wrinkles when it is folded.

[0076] It is worth noting that if the value of i is too large, the continuity between the tabs 311 will be too poor, resulting in poor welding continuity when welding the tabs 31 and the housing 1. This will lead to a lower welding effect between the tabs 31 and the housing 1, increasing the risk of connection failure. If the value of i is too small, the overall area of ​​the tabs 311 will be too large, which will easily cause wrinkles when folding the tabs 311. After stacking, the gap between the tabs 311 will be too large, affecting the current flow capacity between the tabs 31 and the housing 1.

[0077] Optionally, the value of i can be any one of 0.01mm, 0.015mm, 0.02mm, 0.025mm, 0.03mm, 0.035mm, 0.04mm, 0.045mm, or 0.05mm, or a value between any two of these values.

[0078] In one embodiment, such as Figure 9 As shown, the lead-out height of the tab body 311 is j, which satisfies 2mm≤j≤10mm. This setting ensures the welding effect between the tab body 31 and the housing 1, while facilitating the folding of the tab body 311 and the stacking of adjacent tab bodies 311.

[0079] It is worth noting that if the value of j is too small, the continuity between the tabs 311 will be too poor after the tabs 311 are folded onto the end face of the cell 2. This will result in poor welding continuity when welding the tabs 31 and the housing 1, leading to a lower welding effect and an increased risk of connection failure. If the value of j is too large, interference with other tabs 311 is likely when the tabs 311 are folded onto the end face of the cell 2, affecting the folding of other tabs 311.

[0080] Optionally, j can be any value from 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, or a value between any two of these values.

[0081] In one embodiment, the tab 31 includes a negative tab 313, which is welded to the housing 1 to form a solder mark 4. The negative tab 313 includes copper. It should be noted that the melting point difference between titanium and copper is relatively small, which facilitates welding. Furthermore, copper has a higher thermal conductivity than aluminum, which can quickly conduct heat, helping to maintain the temperature uniformity of the welding area and reducing the risk of local overheating.

[0082] In one embodiment, such as Figure 3 As shown, the tab portion 31 includes a positive tab 312 and a negative tab 313, which are located at the same end of the cell 2. The value of b satisfies 0.05 ≤ b ≤ 2.5. It is worth noting that the simultaneous lead-out of the positive tab 312 and the negative tab 313 at the same end of the cell 2, and their opposite arrangement to the same wall surface of the housing 1, limits the welding area of ​​the weld mark 4 formed by welding the tab portion 31 and the housing 1. This increases the risk of connection failure between the tab portion 31 and the housing 1. Therefore, by further controlling the value of b, the welding strength between the housing 1 and the tab portion 31 can be further improved, reducing the risk of connection failure between the housing 1 and the electrode terminal 3.

[0083] Furthermore, in one embodiment, such as Figure 10 As shown, the area of ​​the current collector 32 projected onto the first end face 13 is S2, where S and S2 satisfy S2 < 0.5S, and the value of b satisfies 0.05 ≤ b ≤ 2.2. With this configuration, when welding the current collector 32 and the housing 1, the welding area of ​​the weld mark 4 is relatively small, increasing the risk of connection failure between the electrode tab 31 and the housing 1. Therefore, by further controlling the value of b, the welding strength between the housing 1 and the electrode tab 31 is further improved, reducing the risk of connection failure between the housing 1 and the electrode terminal 3.

[0084] Furthermore, in one embodiment, such as Figure 11As shown, the collector plate 32 has an arc-shaped outer edge, and the solder mark 4 is spaced apart from the arc-shaped outer edge. The value of b is within the range of 0.05 ≤ b ≤ 2. With this setting, when welding the collector plate 32 and the housing 1, the maximum arc length of the collector plate 32 cannot be utilized (the arc-shaped outer edge corresponds to the maximum arc length), resulting in a limited length of the solder mark 4. This increases the risk of connection failure between the electrode tab 31 and the housing 1. Therefore, by further controlling the value of b, the welding strength between the housing 1 and the electrode tab 31 can be further improved, reducing the risk of connection failure between the housing 1 and the electrode terminal 3.

[0085] Specifically, such as Figure 11 As shown, the distance k between the arc-shaped outer edge of the collector plate 32 and the solder mark 4 is 3mm≤k≤5mm. This setting ensures the welding strength between the tab 31 and the housing 1, facilitates the welding process, and avoids burning the battery cell 2.

[0086] It is worth noting that the collector plate 32 may have a stepped portion in the area near the outer edge. In this embodiment, the "arc outer edge of the collector plate 32" mentioned above refers to the outer edge of the planar portion of the collector plate 32 where no stepped portion is formed.

[0087] It is worth noting that if the value of k is too small, the distance between the solder mark 4 and the arc-shaped outer edge of the current collector 32 will be too close, making it inconvenient to set up the welding fixture during welding, and it is easy to burn the diaphragm 23 on the outer edge of the cell 2. If the value of k is too large, it will further reduce the length of the solder mark 4, leading to an increased risk of connection failure between the tab 31 and the housing 1.

[0088] Optionally, k can be any value from 3mm, 3.2mm, 3.5mm, 3.8mm, 4mm, 4.2mm, 4.5mm, 4.8mm, 5mm, or a value between any two of these values.

[0089] In another implementation, such as Figure 12 As shown, the electrode portion 31 includes a positive electrode tab 312 and a negative electrode tab 313, which are located at opposite ends of the battery cell 2. The current collector 32 is circular, and the value of b satisfies 0.1 ≤ b ≤ 4. This configuration increases the welding area of ​​the solder mark 4, improves the welding reliability between the housing 1 and the current collector 32, and reduces the risk of connection failure between the housing 1 and the current collector 32. Therefore, in this embodiment, the value of b can be further controlled to further reduce the heat required for welding the housing 1 and the current collector 32, thereby further avoiding damage to the battery cell 2 and the risk of short circuit.

[0090] In one embodiment, such as Figure 4As shown, the housing 1 includes a housing body 11 and an end cap 14. At least one end of the housing body 11 has an opening, and the end cap 14 is disposed at the opening. The electrode terminal 3 is welded to the end cap 14 to form the weld mark 4. An insulating member 5 is provided between the end cap 14 and the battery cell 2. By providing the insulating member 5, the heat transfer to the battery cell 2 during the welding of the electrode terminal 3 and the end cap 14 can be reduced, further avoiding damage to the battery cell 2 and safety issues caused by short circuits between the positive and negative electrodes.

[0091] In one embodiment, such as Figure 13 As shown, the battery cell 2 includes a positive electrode 21, a negative electrode 22, and a separator 23. The positive electrode 21, separator 23, and negative electrode 22 are stacked together. The thickness of the separator 23 is m, which satisfies 4μm≤m≤15μm. This arrangement reduces the risk of separator 23 shrinkage while ensuring the battery's heat dissipation performance.

[0092] It is worth noting that if the value of m is too small, the separator 23 is prone to shrinkage due to heat when welding the electrode terminal 3 and the casing 1, which increases the risk of short circuit between the positive and negative terminals of the battery and affects the battery's safety performance. If the value of m is too large, the heat generated during the charging and discharging process of the battery is not easily dissipated, increasing the risk of thermal runaway.

[0093] Optionally, m can take any value from 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, or a value between any two values.

[0094] It is worth noting that the battery cell 2 is formed by stacking a positive electrode 21, a negative electrode 22, and a separator 23 disposed between them. The positive electrode 21 includes a positive current collector and a positive active material. The positive current collector can be made of metal materials such as aluminum foil, nickel foil, or stainless steel, or a composite foil formed by combining metals and insulating materials. The positive active material includes a main positive active material, a conductive agent, and a binder. The main positive active material includes one or more of lithium-containing positive active materials such as lithium iron phosphate, ternary materials containing nickel, cobalt, and manganese, and lithium manganese iron phosphate. Similarly, the negative electrode 22 includes a negative current collector and a negative active material. The negative current collector can be made of metal materials such as copper foil, aluminum foil, or stainless steel, or a composite foil formed by combining metals and insulating materials. The negative active material includes a main negative active material, a conductive agent, and a binder. The main negative active material includes one or more of artificial graphite, natural graphite, silicon carbide, silicon oxide, and lithium titanate.

[0095] It is worth noting that the electrode post can be made of metals such as aluminum, aluminum alloy, copper-aluminum composite, and nickel.

[0096] It is worth noting that the current collector 32 is used to make electrical connections with the electrode tab 31 led out from the battery cell 2 and the housing 1, so as to transfer the current from the battery cell 2 to the housing 1.

[0097] The present application will be further described in detail below with reference to specific embodiments, which should not be construed as limiting the scope of protection claimed in the present application.

[0098] The preparation of the example battery and the comparative battery includes the following steps:

[0099] (1) Preparation of the positive electrode:

[0100] The prepared positive electrode active material, conductive agent acetylene black, and binder are mixed, and a solvent is added. The mixture is stirred under vacuum until the system is homogeneous to obtain a positive electrode slurry. The positive electrode slurry is uniformly coated on both surfaces of the positive electrode current collector aluminum foil, dried at room temperature, and then transferred to an oven for further drying. After cold pressing and slitting, the positive electrode sheet is obtained. Specifically, the mass ratio of positive electrode material: conductive agent: binder satisfies (92-98):(4-1):(4-1).

[0101] (2) Preparation of negative electrode:

[0102] The negative electrode active material graphite, conductive agent acetylene black, thickener CMC, and binder SBR are mixed, and deionized water is added as a solvent. The mixture is stirred under vacuum until the system is homogeneous to obtain a negative electrode slurry. The negative electrode slurry is uniformly coated on both surfaces of the negative electrode current collector copper foil, air-dried at room temperature, and then transferred to an oven for further drying. After cold pressing and slitting, the negative electrode sheet is obtained. Specifically, the ratio of negative electrode graphite: conductive agent: thickener: binder is (90-96): (4-2): (2-1): (4-1).

[0103] (3) Preparation of electrolyte:

[0104] Ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) were mixed in a volume ratio of 1:1:1 to obtain an organic solvent. Then, a thoroughly dried lithium salt was dissolved in the mixed organic solvent to prepare an electrolyte with a concentration of 1 mol / L.

[0105] (4) Preparation of the diaphragm:

[0106] Polyethylene film is selected as the diaphragm.

[0107] (5) Preparation of lithium-ion batteries:

[0108] The above-mentioned positive electrode sheet, separator, and negative electrode sheet are stacked in sequence, and then wound or stacked to obtain a bare cell. The bare cell is placed in an outer packaging shell, dried, injected with electrolyte, and then packaged, left to stand, formed, and calibrated to obtain a lithium-ion battery.

[0109] The positive electrode active material can be selected from one or more lithium-containing positive electrode active materials, including lithium iron phosphate, ternary materials containing nickel, cobalt, and manganese, and lithium manganese iron phosphate; the negative electrode active material can be selected from one or more negative electrode active materials, including artificial graphite, natural graphite, silicon carbide, silicon oxide, and lithium titanate.

[0110] In this application, the positive electrode active material is selected from a nickel-cobalt-manganese ternary system, with the structural formula LiNi. 0.9 Co 0.05 Mn 0.05 Taking O2 as an example; the negative electrode material is selected from artificial graphite. Optionally, in other embodiments, the positive electrode material can be selected from one or more of other nickel-cobalt-manganese ternary materials, lithium iron phosphate, and lithium manganese iron phosphate; the negative electrode can also include one or more of silicon-carbon negative electrode or natural graphite.

[0111] The difference between the batteries in each embodiment and the comparative battery lies in the values ​​of a, b, and c, as shown in Table 1.

[0112] The relevant performance of the batteries in the above embodiments and comparative examples was tested, and the test results are recorded in Table 1. The test methods are as follows:

[0113] 1. Battery overcurrent capability test

[0114] For each embodiment and comparative example, 10 batteries were taken. The batteries were discharged at 0.33C to the lower limit voltage of 2.5V, left to stand for 60 minutes, and the temperature at this point was measured and recorded as t1. The batteries were then charged at 1C to the upper limit voltage of 4.25V, with a cutoff current of 0.05C, and the time was recorded as T. The temperature at this point was also measured and recorded as t2. The temperature rise rate was calculated using the formula: temperature rise rate = (t2 - t1) / T. If the temperature rise rate is less than or equal to 0.9℃ / min, it is considered good; if the temperature rise rate is greater than 0.9℃ / min and less than or equal to 1.0℃ / min, it is considered acceptable; if the temperature rise rate is greater than 1.0℃ / min, it is considered unacceptable.

[0115] 2. Battery short circuit test

[0116] For each embodiment and comparative example, 10 batteries were taken. The batteries were discharged at 0.33C to the lower limit voltage of 2.5V, and allowed to stand for 60 minutes. Then, an internal resistance meter was connected at one end to the terminal and the other end to the casing to test the voltage between the terminal and the casing. If the voltage was between 4.2-4.3V, it was considered good; if the voltage was between 3.8V and less than 4.2V, it was considered a minor short circuit; if the voltage was less than 3.8V, it was considered a short circuit, and the battery could not be used normally.

[0117] The Ti element content can be tested using X-ray fluorescence spectrometry to determine the content of each element in the shell. The specific steps are as follows:

[0118] (1) Sample preparation: First, the shell sample needs to be properly treated to facilitate X-ray penetration and excitation of fluorescence. This may include steps such as cutting, grinding, and polishing to ensure that the sample surface is flat and free of contamination;

[0119] (2) X-ray excitation: High-energy X-rays are used to irradiate the sample surface, exciting the characteristic X-ray fluorescence of each element. The wavelength or energy characteristics of these fluorescence spectra correspond to the element types, thus allowing the determination of which elements are contained in the sample;

[0120] (3) Spectral collection and analysis: X-rays reflected from the sample surface and fluorescence spectra emitted are collected using a spectrometer. The type and content of elements can be determined by the position and intensity of characteristic spectral lines;

[0121] (4) Matrix effect correction: Due to the interaction between various elements in the shell (matrix effect), the collected spectral data needs to be corrected to eliminate the influence of this interaction on the analysis results and improve the accuracy of the analysis.

[0122] (5) Interpretation of results: Based on the corrected data, the content of each element in the shell can be calculated.

[0123] Table 1:

[0124] Example 1 90.5 105 5.72 4.930 Less than or equal to 0.9℃ / min Between 4.2-4.3V Example 2 93.6 155 5.12 3.092 Less than or equal to 0.9℃ / min Between 4.2-4.3V Example 3 95.5 203 4.53 2.131 Less than or equal to 0.9℃ / min Between 4.2-4.3V Example 4 97.2 292 3.58 1.192 Less than or equal to 0.9℃ / min Between 4.2-4.3V Example 5 98.5 496 2.96 0.588 Less than or equal to 0.9℃ / min Between 4.2-4.3V Example 6 99.5 525 2.35 0.445 Less than or equal to 0.9℃ / min Between 4.2-4.3V Example 7 99.95 598 1.54 0.257 Less than or equal to 0.9℃ / min Between 4.2-4.3V Example 8 99.2 472 1.25 0.263 Less than or equal to 0.9℃ / min Between 4.2-4.3V Example 9 91.2 119 6.48 4.966 Less than or equal to 0.9℃ / min Between 4.2-4.3V Example 10 99.99 498 0.05 0.010 Less than or equal to 0.9℃ / min Between 4.2-4.3V Example 11 98.6 415 0.26 0.062 Less than or equal to 0.9℃ / min Between 4.2-4.3V Example 12 99.5 95 4.56 4.776 Greater than 0.9 and less than or equal to 1.0℃ / min Between 4.2-4.3V Example 13 95.6 606 0.10 0.016 Greater than 0.9 and less than or equal to 1.0℃ / min Voltage 3.8-4.2V, slight short circuit Example 14 96.5 175 0.18 0.099 Less than or equal to 0.9℃ / min Between 4.2-4.3V Example 15 99.2 512 4.53 0.878 Less than or equal to 0.9℃ / min Between 4.2-4.3V Example 16 99.99 195 3 1.538 Less than or equal to 0.9℃ / min Between 4.2-4.3V Example 17 99.5 472 0.22 0.046 Less than or equal to 0.9℃ / min Between 4.2-4.3V Example 18 99.8 346 1.86 0.536 Less than or equal to 0.9℃ / min Between 4.2-4.3V Example 19 98.1 235 2.27 0.948 Less than or equal to 0.9℃ / min Between 4.2-4.3V Comparative Example 1 99.9 86 7.50 8.712 Greater than 1.0℃ / min Voltage 3.8-4.2V, slight short circuit Comparative Example 2 90 592 0.05 0.007 Greater than 1.0℃ / min Voltage less than 3.8V Comparative Example 3 95.6 645 0.03 0.004 Greater than 1.0℃ / min Voltage less than 3.8V

[0125] As can be seen from Table 1, in Examples 1 to 19, the value of b×c / a is in the range of 0.01 to 5. Therefore, for the batteries in Examples 1 to 19, the temperature rise rate in the overcurrent capacity test is less than or equal to 1.0℃ / min, and the battery overcurrent capacity test is qualified. In the short circuit test, the battery voltage is not less than 3.8V, and the battery short circuit test is qualified.

[0126] As shown in Table 1, in Example 12, the value of 'a' is not within the range of 100N to 600N and is less than 100N, resulting in a relatively poor connection between electrode terminal 3 and housing 1, increased current transmission impedance between electrode terminal 3 and housing 1, and increased heat generation during current transmission. In Example 13, the value of 'a' is not within the range of 100N to 600N and is greater than 600N, causing the diaphragm 23 to shrink, increasing the risk of short circuit between the positive and negative electrodes.

[0127] As can be seen from Table 1, in Comparative Example 1, the value of b×c / a is not in the range of 0.01 to 5 and is greater than 5. Therefore, the battery in Comparative Example 1 has a temperature rise rate greater than 1.0℃ / min in the overcurrent capacity test, and the battery overcurrent capacity test is unqualified.

[0128] As can be seen from Table 1, in Comparative Example 2 and Comparative Example 3, the value of b×c / a is not in the range of 0.01 to 5 and is less than 0.01. Therefore, in the short circuit test, the battery voltage of Comparative Example 2 and Comparative Example 3 is less than 3.8V, and the battery cannot be used normally due to short circuit.

[0129] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A battery, characterized in that, include: The battery is housed in a housing (1), a battery cell (2), and an electrode terminal (3). The battery cell (2) is disposed inside the housing (1). The housing (1) contains titanium. The electrode terminal (3) is electrically connected to the battery cell (2). At least a portion of the electrode terminal (3) is welded to the housing (1) to form a solder mark (4). The peel strength between the housing (1) and the electrode terminal (3) is a N. The thickness of the housing (1) is T1 mm. The thickness of the electrode terminal (3) welded to the housing (1) is T2 mm. The titanium content in the housing (1) is c%, where c ≥ 90, b = |T1 / T2-1|, and 0.01 ≤ b × c / a ≤ 5. The peel strength a N between the housing (1) and the electrode terminal (3) satisfies 100N≤a N≤600N; The thickness T1 mm of the housing (1) and the thickness T2 mm of the electrode terminal (3) welded to the housing (1) satisfy 0.05≤b=|T1 / T2-1|≤6.5; The thickness T1 mm of the shell (1) satisfies 0.3 mm ≤ T1 mm ≤ 1.5 mm; The thickness T2 mm of the electrode terminal (3) welded to the housing (1) satisfies 0.09 mm ≤ T2 mm ≤ 2 mm.

2. The battery according to claim 1, characterized in that, The electrode terminal (3) includes a tab (31) and a current collector (32). The tab (31) is disposed between the battery cell (2) and the current collector (32). The current collector (32) is welded to the housing (1) to form the solder mark (4). The thickness of the collector plate (32) is f, which satisfies 0.35mm≤f≤1mm; the thickness of the electrode ear (31) is g, which satisfies 0.09mm≤g≤2mm.

3. The battery according to claim 2, characterized in that, The shell (1) includes a shell body (11) and an end wall (12) connected to one end of the shell body (11). A recess (121) is provided on the end wall (12). The solder mark (4) is located in the recess (121). The value of b is 0.1≤b≤2.

8.

4. The battery according to claim 3, characterized in that, The remaining thickness of the shell (1) in the recess (121) is H, which satisfies 0.6mm≤H≤0.9mm; the width of the recess (121) is W, which satisfies 1.4mm≤W≤2.5mm.

5. The battery according to claim 3, characterized in that, The collector disk (32) includes copper, and the value of b is 0.1≤b≤2.

6. The battery according to claim 1, characterized in that, The electrode terminal (3) includes a tab (31), the housing (1) is welded to the tab (31) to form the solder mark (4), the tab (31) includes a plurality of tab plates (311) stacked together, and the value of b is 0.05≤b≤4.

7. The battery according to claim 1, characterized in that, The weld depth of the weld (4) is d, which satisfies 0.08mm≤d≤0.3mm; the weld width of the weld (4) is e, which satisfies 1mm≤e≤2.5mm; the weld (4) is disposed on the first end face (13) of the shell (1), the area of ​​the first end face (13) is S, and the area of ​​the orthographic projection of the weld (4) on the first end face (13) is S1. The values ​​of S and S1 satisfy 0.0048≤S1 / S≤0.

008.

8. The battery according to claim 1, characterized in that, The battery cell (2) is cylindrical and includes several wound layers stacked radially. The electrode terminal (3) includes a tab (31) connected to the battery cell (2). The tab (31) includes several tab pieces (311) stacked. The wound layer is connected to at least one tab piece (311). The tab (31) has a first point and a second point spaced radially apart. The thickness of the tab (31) at the first point is different from the thickness of the tab (31) at the second point. The value of b is 0.05≤b≤4.

9. The battery according to claim 8, characterized in that, The maximum thickness of the tab (31) is h1, and the minimum thickness of the tab (31) is h2, where h1 and h2 satisfy h1-h2≤1.75mm.

10. The battery according to claim 9, characterized in that, At the position where the electrode tab (31) has the maximum thickness, the number of layers of the electrode tab body (311) is not less than 10 layers, and the value of b is within the range of 0.05≤b≤3.

5.

11. The battery according to claim 8, characterized in that, Each of the winding layers is provided with a plurality of tabs (311) spaced circumferentially, and the value of b is in the range of 0.05≤b≤3.

12. The battery according to claim 11, characterized in that, The distance between adjacent tabs (311) on one of the winding layers is i, which satisfies 0.01mm≤i≤0.05mm.

13. The battery according to claim 8, characterized in that, The lead-out height of the tab body (311) is j, which satisfies 2mm≤j≤10mm.

14. The battery according to claim 8, characterized in that, The tab portion (31) includes a negative tab (313), which is welded to the housing (1) to form the solder mark (4), and the negative tab (313) includes copper.

15. The battery according to claim 8, characterized in that, The tab portion (31) includes a positive tab (312) and a negative tab (313), the positive tab (312) and the negative tab (313) are located at the same end of the cell (2), and the value of b is 0.05≤b≤2.

5.

16. The battery according to claim 15, characterized in that, The electrode terminal (3) also includes a current collector (32), the tab (31) is connected to the current collector (32), the current collector (32) is welded to the housing (1) to form the solder mark (4), the solder mark (4) is disposed on the first end face (13) of the housing (1), the area of ​​the first end face (13) is S, the area of ​​the current collector (32) on the first end face (13) is S2, the values ​​of S and S2 satisfy S2 < 0.5S, and the value range of b satisfies 0.05 ≤ b ≤ 2.

2.

17. The battery according to claim 16, characterized in that, The collector plate (32) has an arc-shaped outer edge, and the solder mark (4) is spaced apart from the arc-shaped outer edge. The value of b is 0.05≤b≤2.

18. The battery according to claim 17, characterized in that, Along the radial direction, the distance between the arc-shaped outer edge of the collector plate (32) and the solder mark (4) is k, which satisfies 3mm≤k≤5mm.

19. The battery according to claim 8, characterized in that, The electrode terminal (3) also includes a current collector (32), the tab (31) is connected to the current collector (32), the current collector (32) is welded to the housing (1) and forms the solder mark (4), the tab (31) includes a positive tab (312) and a negative tab (313), the positive tab (312) and the negative tab (313) are located at opposite ends of the battery cell (2), the current collector (32) is circular, and the value of b satisfies 0.1≤b≤4.

20. The battery according to claim 1, characterized in that, The housing (1) includes a housing body (11) and an end cap (14). At least one end of the housing body (11) is provided with an opening. The end cap (14) is provided at the opening. The electrode terminal (3) is welded to the end cap (14) to form the solder mark (4). An insulating element (5) is provided between the end cap (14) and the battery cell (2).

21. The battery according to claim 1, characterized in that, The battery cell (2) includes a positive electrode (21), a negative electrode (22) and a separator (23). The positive electrode (21), the separator (23) and the negative electrode (22) are stacked. The thickness of the separator (23) is m, which satisfies 4μm≤m≤15μm.

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