Battery pack and single batteries thereof

Abstract

The battery pack comprises a battery shell and a battery cell, the battery cell is placed in the battery shell, the battery shell is provided with an anti-explosion valve, the anti-explosion valve comprises a weak part, the battery shell is provided with a blocking part, the blocking part is arranged on the periphery of the weak part, and the thickness of the blocking part is larger than that of the weak part. The blocking part comprises a blocking main body structure, the area surrounded by the weak part is S1, the area surrounded by the outer edge of the blocking part is S2, S1 and S2 meet the condition that 0.03 * 104 < = S1 * (S2-S1) / (Q * h1 / h2) < = 20 * 104, Q is the battery capacity, h1 is the thickness of a shell provided with the anti-explosion valve, and h2 is the thickness sum of the battery shell and the blocking main body structure; the blocking body structure comprises a blocking table. According to the battery pack and the single batteries thereof, the probability that the adjacent single batteries are burnt when the single batteries are in thermal runaway is reduced, and the occurrence of heat spreading when the batteries are in thermal runaway is reduced.

Description

[0001] This application is a divisional application of application No. 2025106922472, filed on May 27, 2025, entitled "Battery pack and battery cell thereof". TECHNICAL FIELD

[0002] The present application relates to the technical field of batteries, in particular to a battery pack and a battery cell thereof. BACKGROUND

[0003] Battery thermal runaway refers to the abnormal rise in temperature inside the battery, which leads to uncontrolled chemical reactions inside the battery, and eventually may cause the battery to fail, catch fire or even explode. When the battery thermal runaway occurs, the explosion-proof valve opens to release heat. Due to the large amount of heat released, the explosion-proof valve ring is easily melted, and the heat from the flame combustion is transferred to the adjacent battery cell, causing heat spread and triggering thermal runaway in the adjacent battery. SUMMARY

[0004] Therefore, the present application provides a battery cell, which reduces the probability of burning adjacent battery cells when the battery cell thermal runaway occurs and reduces the occurrence of heat spread when the battery thermal runaway occurs.

[0005] The present application also provides a battery pack.

[0006] To achieve the above-mentioned purpose, the present application provides the following technical scheme:

[0007] A battery cell includes a battery shell and a battery cell, the battery cell is placed in the battery shell, the battery shell is provided with an explosion-proof valve, the explosion-proof valve includes a weak part, the battery shell is provided with a blocking part, the blocking part is arranged on the periphery of the weak part, the thickness of the blocking part is greater than the thickness of the weak part, the blocking part includes a blocking main structure, the area surrounded by the weak part is S1, the area surrounded by the outer edge of the blocking part is S2, S1 and S2 satisfy 0.03*10 4 ≤S1*(S2-S1) / (Q*h1 / h2)≤20*10 4 , wherein Q is the battery capacity, unit Ah, h1 is the thickness of the shell where the explosion-proof valve is arranged, unit mm, h2 is the sum of the thickness of the battery shell and the blocking main structure, unit mm, S1 and S2 are mm 2 ;

[0008] The blocking main structure includes a blocking platform, the blocking platform is protrudingly arranged on the outer surface of the battery shell, and the height of the blocking platform is 0.5-3.5mm.

[0009] The blocking platform is arranged around the weak part.

[0010] As can be seen from the above technical solution, the battery cell provided by the present invention, by setting a barrier portion on the outside of the weak part of the explosion-proof valve, wherein the barrier portion is located on the periphery of the weak part and the thickness of the barrier portion is greater than the thickness of the weak part, thus preventing the periphery of the explosion-proof valve from melting when the heat release of the explosion-proof valve is large. This effectively reduces the risk of the explosion-proof valve periphery melting and causing the jet flame to burn through the large surface of the battery cell, reducing the probability of the battery cell burning adjacent battery cells when thermal runaway occurs, and reducing the occurrence of heat propagation during battery thermal runaway. The barrier main structure includes a barrier platform protruding from the battery casing, which increases the thickness around the explosion-proof hole and reduces the risk of heat propagation during thermal runaway of the battery. The battery cell of the present invention, by comprehensively considering the relationship between S1*(S2-S1), Q, and h1 / h2, reduces the risk of heat transfer to adjacent batteries and causing thermal runaway in adjacent batteries when thermal runaway occurs. The value of S1*(S2-S1) / (Q*h1 / h2) cannot be too small, because the internal heat generation of the battery is large. If the value of the above formula is too small, the effect of the barrier part in blocking heat transfer will be poor, which will increase the risk of thermal runaway in adjacent batteries. The value of the above formula cannot be too large, otherwise the energy density of the battery will decrease.

[0011] The present invention also provides a battery pack comprising a plurality of battery cells stacked together, wherein the battery cells are the aforementioned battery cells, and a heat insulation pad is provided between adjacent battery cells, wherein the thickness of the heat insulation pad is 1-5mm.

[0012] The battery pack of the present invention includes the above-described battery cells, and therefore has the advantages of the above-described battery cells, which will not be repeated here. Attached Figure Description

[0013] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1 This is a structural schematic diagram of a battery cell from one angle, provided in an embodiment of the present invention.

[0015] Figure 2 This is a structural schematic diagram of a battery cell from another angle provided in an embodiment of the present invention;

[0016] Figure 3 for Figure 2 A schematic diagram of the cross-sectional structure at position AA in the middle;

[0017] Figure 4 for Figure 3A magnified schematic diagram of a portion of section B in the middle;

[0018] Figure 5 This is a schematic diagram of the structure in which the barrier stage is directly connected to the protective patch according to an embodiment of the present invention;

[0019] Figure 6 A schematic diagram of a first barrier stage provided on a barrier stage according to an embodiment of the present invention;

[0020] Figure 7 A schematic diagram of the structure in which the barrier stage is connected to the protective patch via the first barrier stage, according to an embodiment of the present invention;

[0021] Figure 8 A schematic diagram showing the area of ​​the weak point of an explosion-proof valve provided in an embodiment of the present invention;

[0022] Figure 9 This is a cross-sectional view of the explosion-proof sheet provided in an embodiment of the present invention;

[0023] Figure 10 This is a structural schematic diagram of the area enclosed by the barrier portion provided in an embodiment of the present invention;

[0024] Figure 11 This is a schematic diagram of the barrier stage provided in another embodiment of the present invention;

[0025] Figure 12 A partial cross-sectional view of the location of the barrier groove provided in an embodiment of the present invention;

[0026] Figure 13 This is a schematic diagram of the structure after placing a heat insulation component in the barrier groove according to an embodiment of the present invention;

[0027] Figure 14 for Figure 13 A cross-sectional view of the EE location;

[0028] Figure 15 This is a schematic diagram of the structure of an explosion-proof sheet provided in an embodiment of the present invention;

[0029] Figure 16 for Figure 15 A schematic diagram of the area of ​​the weak point of the explosion-proof valve in the diagram;

[0030] Figure 17 This is a schematic diagram of the structure of an explosion-proof sheet provided in another embodiment of the present invention;

[0031] Figure 18 for Figure 17 A schematic diagram of the area of ​​the weak point of the explosion-proof valve in the diagram;

[0032] Figure 19This is a structural schematic diagram showing the difference between the area enclosed by the barrier portion and the area of ​​the weak portion provided in an embodiment of the present invention.

[0033] in:

[0034] 1. Battery casing,

[0035] 101. Shell body; 1011. Large side face; 102. Cover plate; 103. Protrusion; 104. Barrier groove.

[0036] 2. Protective patch,

[0037] 3. Barrier platform,

[0038] 301. First barrier platform; 302. Second barrier platform.

[0039] 4. Battery cells,

[0040] 5. Explosion-proof hole,

[0041] 6. Explosion-proof sheet,

[0042] 601. Weak points

[0043] 7. Thermal insulation components. Detailed Implementation

[0044] This invention discloses a battery cell that reduces the probability of a battery cell burning into adjacent battery cells during thermal runaway, and reduces the occurrence of thermal propagation during battery thermal runaway.

[0045] The present invention also discloses a battery pack.

[0046] 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, and 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.

[0047] See Figures 1 to 14 The battery cell of the present invention includes a battery casing 1 and a battery cell 4. The battery casing 1 is disposed on the outermost side of the battery cell 4 to protect the battery cell 4. The material of the battery casing 1 can be, but is not limited to, aluminum, steel, or aluminum alloy. Specifically, the material of the battery casing 1 can be aluminum-manganese alloy, aluminum-magnesium alloy, stainless steel, nickel-plated steel, carbon steel, or titanium, etc.

[0048] The battery cell 4 includes a positive electrode sheet, a negative electrode sheet, and a separator disposed between them. The positive electrode sheet, negative electrode sheet, and separator are stacked to form the battery cell body. The positive electrode sheet includes a positive current collector and a positive active material. The positive current collector can be a metal material such as aluminum foil, nickel foil, or stainless steel; or the positive current collector can be a composite foil formed by combining metal and insulating materials. The positive active material includes a positive active material, a conductive agent, and a binder. The 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. The negative electrode sheet includes a negative current collector and a negative active material. The negative current collector can be a metal material such as copper foil, aluminum foil, or stainless steel, or a composite foil formed by combining metal and insulating materials. The negative active material includes a negative active material, a conductive agent, and a binder. The negative active material includes one or more of negative active materials such as artificial graphite, natural graphite, silicon carbide, silicon oxide, and lithium titanate.

[0049] An explosion-proof valve is provided on the battery casing 1. The explosion-proof valve includes a weak point 601, which is used to break open at the weak point 601 in the event of thermal runaway, releasing heat, dust, etc., from inside the battery. Specifically, the explosion-proof valve may have an explosion-proof hole 5 on the battery casing 1, and the explosion-proof valve includes an explosion-proof plate 6 connected to the explosion-proof hole 5. The weak point 601 on the explosion-proof valve may be a thinned area on the explosion-proof plate 6. The weak point 601 can be arranged circumferentially or at intervals to prevent the explosion-proof plate 6 from flying out.

[0050] The weak part 601 can be directly formed on the explosion-proof sheet 6 by stamping or by laser etching. The weak part 601 also has a scoring structure, in which a groove is first formed, and then scoring grooves are formed by laser etching within the groove. The explosion-proof valve includes the weak part 601, and a barrier part is provided on the battery casing 1. The barrier part is located around the weak part 601, specifically on the side away from the center of the explosion-proof sheet 6. The barrier part is used to improve the heat resistance around the explosion-proof valve. The thickness of the barrier part is greater than the thickness of the weak part 601, thereby improving the melting resistance around the explosion-proof valve. The barrier part includes a barrier body structure, and the area enclosed by the weak part 601 is S1, such as... Figure 8 As shown. The area enclosed by the outer edge of the barrier is S2, as... Figure 10 As shown, the effective area of ​​the barrier is S2-S1, where S1 and S2 satisfy 0.03*10 4 ≤S1*(S2-S1) / (Q*h1 / h2)≤20*10 4 The specific value can be selected as 0.03*10. 4 0.1*10 42*10 4 Or 5*10 4 Where Q is the battery capacity in Ah, h1 is the thickness of the battery casing 1 with the explosion-proof valve installed in mm, h2 is the sum of the thicknesses of the battery casing 1 and the barrier structure in mm, and S1 and S2 are in mm. 2 .

[0051] The main barrier structure includes a barrier platform 3, such as... Figure 1 , Figure 4 and Figure 5 As shown. A barrier platform 3 protrudes from the outer surface of the battery casing 1. The barrier platform 3 increases the thickness around the explosion-proof hole 5 to reduce the thermal propagation of the battery in the event of thermal runaway. The barrier platform 3 is arranged around the weak point 601.

[0052] To increase battery energy density and pursue larger battery capacity, the amount of heat and gas generated during thermal runaway increases. When batteries are stacked, if one battery experiences thermal runaway, heat propagation can easily trigger thermal runaway in adjacent batteries. The battery cell of this invention, by comprehensively controlling the relationship between the above parameters, adjusts the relationship between the area of ​​the barrier portion, the area of ​​the weak portion 601, the battery capacity, and the ratio of the barrier portion thickness to the casing wall thickness. By setting the barrier portion, heat transfer to adjacent batteries is prevented, heat propagation is reduced, and thermal runaway in adjacent batteries is avoided; it also avoids affecting the battery energy density.

[0053] The battery cell of the present invention, by providing a barrier portion outside the weak portion 601 of the explosion-proof valve, wherein the barrier portion is disposed on the periphery of the weak portion 601 and the thickness of the barrier portion is greater than the thickness of the weak portion 601, is designed to prevent the periphery of the explosion-proof valve from melting even when the heat release of the explosion-proof valve is large. This effectively reduces the risk of the explosion-proof valve periphery melting and causing the jet flame to burn through the large surface of the battery cell, and reduces the probability of the battery cell burning adjacent battery cells during thermal runaway, thus reducing the occurrence of heat propagation during battery thermal runaway. The barrier main structure includes a barrier platform 3 protruding from the battery casing 1, which increases the thickness around the explosion-proof hole 5 and reduces the risk of heat propagation during thermal runaway. The battery cell of this invention, by comprehensively considering the relationship between S1*(S2-S1), Q, and h1 / h2, reduces the risk of heat transfer to adjacent batteries during thermal runaway, thus preventing adjacent batteries from experiencing thermal runaway. The value of S1*(S2-S1) / (Q*h1 / h2) cannot be too small because the internal heat generation of the battery is large. If the value of the above formula is too small, the effect of the barrier in preventing heat transfer will be poor, increasing the risk of thermal runaway in adjacent batteries. The value of the above formula cannot be too large either. If the value of the above formula is too large, since the internal capacity of the battery pack is fixed, if the barrier is too large, it will reduce the space for placing the battery cells, affecting the internal space of the battery. Insufficient internal space will cause gas emission to be obstructed, and heat and gas will easily accumulate inside the battery casing 1, unable to be discharged smoothly. During thermal runaway, the battery weight loss rate will not meet the requirements, and heat and gas will not be discharged in time.

[0054] A battery pack is generally composed of multiple battery cells. When battery cells are grouped together, the large faces of adjacent battery cells are arranged adjacently. The large face of a battery cell refers to the side with the largest area of ​​the battery cell.

[0055] In one embodiment, S1 ranges from 100 to 1200 mm. 2 Specifically, it can be 200mm 2 500mm 2 Or 800mm 2 The range of S2-S1 is 100-2850mm. 2 Specifically, it can be 200mm 2 400mm 2 Or 1000mm 2The range of Q is 20-600Ah, specifically 30Ah, 100Ah, or 200Ah; the range of h1 / h2 is 0.1-0.8, specifically 0.2, 0.3, or 0.5. By controlling the ranges of S1 and (S2-S1), the risk of heat spreading to adjacent batteries during thermal runaway is further reduced. By controlling the range of Q, the battery energy density is considered while reducing the risk of thermal runaway in adjacent batteries. By further controlling the ranges of h1 / h2, heat transfer to adjacent batteries during thermal runaway is prevented, thus avoiding thermal runaway in adjacent batteries. This also avoids impacting the internal space of the battery and the gas emission channels, preventing heat and gas from accumulating inside the casing during thermal runaway.

[0056] The barrier platform 3 is at least located on the large side 1011 of the explosion-proof valve near the battery casing 1, such as... Figure 6 As shown. The large surface side 1011 of the battery casing 1 refers to the side with the largest area of ​​the battery casing 1. When multiple battery cells are grouped together, the large surface sides 1011 of adjacent battery cells are in contact or spaced apart by heat insulation pads. In one embodiment, the barrier platform 3 continuously surrounds the weak part 601. Here, "continuously surrounding" means that the barrier platform 3 is continuously arranged around the circumference, such as... Figure 6 As shown, in this embodiment, the range of h1 / h2 is 0.1-0.7, and h1 / h2 can be 0.3 or 0.4. By continuously surrounding the weak part 601 with the barrier platform 3, the heat blocking effect of the barrier platform 3 is improved. h1 / h2 is further controlled within the range of 0.1-0.7 to reduce the space occupied by the barrier platform 3 on the battery casing 1, avoid affecting the exhaust space inside the battery casing 1, and affect the smooth pressure relief of the explosion-proof valve.

[0057] In another embodiment, a plurality of barrier platforms 3 are provided, spaced apart around the weak portion 601, i.e., the barrier platforms 3 are discontinuously arranged around the perimeter. This spaced-apart arrangement of the barrier platforms 3 reduces their weight, thereby reducing the overall weight of the casing and improving battery energy density. However, due to the discontinuous arrangement of the barrier platforms 3, their heat-blocking effect is weakened. By controlling the range of h1 / h2, the risk of thermal runaway in adjacent batteries can be further reduced. Figure 11 As shown, in this embodiment, the range of h1 / h2 is 0.3-0.8, and h1 / h2 can be 0.3, 0.4 or 0.7.

[0058] Correspondingly, the weak point 601 on the explosion-proof sheet 6 can be continuously or discontinuously arranged. When the weak point 601 is continuously arranged, that is, the thinning area of ​​the weak point 601 is continuously arranged along the perimeter, making the thinning area a closed shape. In this case, the value range of h1 / h2 is 0.25-0.5, specifically 0.25, 0.35, or 0.4. The weak point 601 can also be discontinuously arranged around the perimeter, that is, the weak point 601 has some unthinned areas, to avoid the probability of the explosion-proof sheet 6 flying out from the area within the weak point 601 and causing adjacent batteries to overheat, thus reducing the risk of thermal runaway. In this case, the value range of h1 / h2 is 0.3-0.6, specifically 0.35, 0.4, or 0.5.

[0059] Specifically, the spacing between adjacent barrier platforms 3 is 1-10mm, and can be 3mm, 5mm, or 8mm. The distance between adjacent barrier platforms 3 should not be too large, as this will increase heat leakage from the gaps between the barrier platforms 3, potentially affecting adjacent batteries. Conversely, if the spacing between the barrier platforms 3 is too small, resulting in overly dense arrangement, it will also increase the weight of the battery casing 1, affecting the battery energy density. The width of the barrier platform 3 is 3-50mm, specifically 5mm, 15mm, or 40mm. The width of the barrier platform 3 refers to the distance between the two sides of the barrier platform 3 closest to and furthest from the weak point 601.

[0060] To improve thermal insulation performance, the barrier stage 3 includes a first barrier stage 301 and a second barrier stage 302, such as... Figure 6 As shown, a first barrier platform 301 is arranged around the weak portion 601, and the first barrier platform 301 is located between the second barrier platform 302 and the weak portion 601. The height ratio of the first barrier platform 301 to the second barrier platform 302 is 0.6-6. The height ratio of the first barrier platform 301 to the second barrier platform 302 can be 0.9, 1.5, or 2.5.

[0061] Furthermore, the distance between the first blocking stage 301 and the second blocking stage 302 is 0-1mm. When the distance between the first blocking stage 301 and the second blocking stage 302 is 0mm, the first blocking stage 301 and the second blocking stage 302 are arranged adjacent to each other, such as... Figure 7 As shown, when the interval between the first barrier stage 301 and the second barrier stage 302 is greater than 0 mm, the first barrier stage 301 and the second barrier stage 302 are set at intervals, and the interval between the first barrier stage 301 and the second barrier stage 302 can be 0.5 mm.

[0062] In one embodiment, the first barrier platform 301 is disposed near the weak portion 601 of the second barrier platform 302, and the first barrier platform 301 is disposed around the weak portion 601. A protective patch 2 is attached to the surface of the first barrier platform 301 away from the second barrier platform 302. In this embodiment, the first barrier platform 301, the second barrier platform 302, and the battery casing 1 can be an integral structure, such as... Figure 7 As shown, it can also be a separate structure. When the barrier platform 3 and the battery casing 1 are separate structures, the barrier platform 3 is bonded or welded to the battery casing 1.

[0063] In another embodiment, the barrier stage 3 does not include the first barrier stage 301, but only includes the second barrier stage 302, such as... Figure 5 As shown, the second barrier platform 302 is arranged around the side of the explosion-proof hole 5 away from the explosion-proof plate 6, as... Figure 1 and Figure 2 As shown. Figure 4 and Figure 5 As shown, the thickness around the explosion-proof hole 5 is increased by providing a second barrier platform 302 with a protrusion on the outside of the explosion-proof hole 5. A protective patch 2 is provided at the end of the explosion-proof hole 5, and the protective patch 2 is adhered to the end of the second barrier platform 302 to protect the explosion-proof sheet 6 and prevent foreign objects from entering the explosion-proof hole 5.

[0064] In another embodiment, the barrier platform 3 is only located on the large side 1011 of the explosion-proof hole 5 near the battery cell, such as... Figure 11 As shown, there are two barrier platforms 3. Both barrier platforms 3 are located on the weak part 601 near the large surface side 1011 of the battery cell, thereby increasing the thickness of the explosion-proof valve near the large surface side 1011 to reduce the risk of igniting adjacent battery cells when the battery cell experiences thermal runaway.

[0065] To facilitate the setting of a barrier platform 3 with a uniform width surrounding structure, the width D1 of the barrier platform 3 is not greater than the distance between the explosion-proof hole 5 and the large surface side 1011 of the battery casing 1. In one embodiment, the width D1 of the barrier platform 3 is less than the distance between the explosion-proof hole 5 and the large surface side 1011 of the battery casing 1, that is, the distance D2 between the barrier platform 3 and the large surface side 1011 of the battery cell is greater than zero, so as to form the barrier platform 3.

[0066] The ratio of the height of the barrier platform 3 to the thickness of the battery casing 1 is 0.25-6, specifically 0.3, 1, or 4. The height of the barrier platform 3 is 0.5-3.5 mm, specifically 1 mm, 2 mm, or 3 mm; the wall thickness of the battery casing 1 is 0.5-3 mm, specifically 1 mm, 1.5 mm, or 2.5 mm. The ratio of the thickness of the barrier platform 3 to the thickness of the battery casing 1 should not be too large. Since the internal space of the battery pack is fixed, a barrier platform 3 that is too large will reduce the space for placing the battery cells, while a ratio that is too small will affect the effectiveness of isolating thermal runaway.

[0067] In another embodiment, the barrier main structure protrudes from the surface of the battery casing 1 toward the cell 4 to form a barrier groove 104. The barrier groove 104 is disposed on the outer surface of the battery casing 1. The barrier main structure includes the barrier groove 104, that is, the barrier groove 104 is disposed on the surface of the barrier main structure away from the cell 4. A heat insulation element 7 is disposed within the barrier groove 104. The barrier groove 104 protrudes toward the side of the battery casing 1 closer to the cell 4, such as... Figure 14 As shown, the impact of the barrier groove 104 structure on the structural strength of the battery casing 1 is reduced. (Refer to...) Figures 12 to 14 A barrier groove 104 is provided around the weak point 601, specifically around the explosion-proof hole 5. By providing a barrier groove 104 structure around the explosion-proof hole 5 on the battery casing 1, the heat conduction during explosion-proof valve eruption can be effectively reduced, minimizing the impact of explosion-proof valve eruption on the large surface side 1011 of the battery cell and reducing the risk of melting of the large surface side 1011. A heat insulation element 7 is placed within the barrier groove 104, further reducing heat conduction during explosion-proof valve eruption and significantly reducing the risk of heat diffusion outwards when the explosion-proof valve melts, effectively preventing the heat from the explosion-proof valve from affecting the structure of the battery casing 1 away from the explosion-proof valve. Furthermore, a first barrier platform 301 is provided around the explosion-proof hole 5.

[0068] In one embodiment, the barrier groove 104 is a groove structure stamped on the battery casing 1, and the barrier groove 104 forms a protruding portion 103 on the side of the battery casing 1 closer to the cell 4, such as... Figure 12 and Figure 14 As shown, the height D3 of the protrusion 103 is the same as the groove depth D5 of the blocking groove 104.

[0069] Furthermore, the depth of the barrier groove 104 is 0.5-3.5mm, specifically 1.5mm, 2.5mm, or 3mm. To ensure the structural strength of the battery casing 1, the depth of the barrier groove 104 cannot be too large. An excessively large depth would occupy a large space inside the battery casing 1, affecting internal gas discharge. In the event of thermal runaway, the discharge of hot gases would be obstructed, causing heat to accumulate inside the battery casing 1. To achieve good heat insulation, the depth of the barrier groove 104 cannot be too small either. The width of the barrier groove 104 is 3-50mm. The width of the barrier groove 104 is 5mm, 15mm, or 40mm. The width of the barrier groove 104 refers to the distance between the two sides of the barrier groove 104 closest to and furthest from the weak point 601. If the width of the barrier groove 104 is too small, it will be difficult to prevent heat conduction; if the width of the barrier groove 104 is too large, it will significantly weaken the structural strength of the battery casing 1.

[0070] The heat insulation component 7 has a melting point higher than that of the battery casing 1, so that when the battery casing 1 around the weak part 601 melts, the heat insulation component 7 can maintain its shape to prevent the battery casing 1 from melting and avoid further melting. The melting point of the heat insulation component 7 is greater than or equal to 700°C.

[0071] Specifically, the battery casing 1 includes a casing body 101 and a cover plate 102. The casing body 101 is a rectangular casing, and the battery cell 4 is placed inside the cavity of the casing body 101. The cover plate 102 is connected to the top opening of the casing body 101. When the battery casing 1 is a square casing, the battery casing 1 includes a first surface and a second surface. There are two first surfaces, which are arranged opposite each other. Two of the four second surfaces are arranged opposite each other in pairs. The area of ​​the first surface is larger than the area of ​​the second surface. The barrier structure is disposed on the second surface between two first surfaces. Here, the first surface refers to the aforementioned large surface side 1011. The distance between the barrier structure and the large surface side 1011 is 3-20mm. The barrier structure is at least disposed at the weak point 601 near the large surface side 1011. The specific distance between the barrier structure and the large surface side 1011 is 4mm, 10mm, or 15mm. By controlling the distance between the barrier main structure and the large-surface side 1011 of the battery, the barrier main structure is prevented from being too close to the edge, making it difficult to form; it is also prevented from being too far apart, resulting in an excessively small width of the barrier main structure, which would affect the heat transfer blocking effect. In one embodiment, the explosion-proof valve is disposed on the cover plate 102, such as... Figure 6 As shown. In another embodiment, the explosion-proof valve is disposed on the housing body 101.

[0072] In other embodiments, the battery casing 1 may also be a cylindrical casing, and the explosion-proof valve is disposed on the end face of the cylindrical casing. In the radial direction, the distance between the outer edge of the barrier main structure and the edge of the end face of the battery casing 1 is 0.5-10mm. In one embodiment, the distance between the barrier main structure and the edge of the end face of the battery casing 1 is 1mm, 4mm or 6mm.

[0073] There are various types of lithium batteries. When the battery cell is a ternary lithium battery, the ternary lithium battery specifically refers to nickel-cobalt-manganese ternary or nickel-cobalt-aluminum ternary materials. The ternary structure of the ternary lithium battery is LiNi. x Co y Mn zO2, wherein x is greater than or equal to 0.5, y is greater than 0 and less than 0.5, z is greater than 0 and less than 0.5, and y+z=0.5; additionally, it may contain doping element M, which is Zr, Ti, Si, Mo, La, Ce, Te, Nb, Ta, Si, Al, W, Sr, V, Y, Mg, Co, F, Cl, S, or L. When the battery cell is a ternary lithium battery, the ratio of h1 to h2 ranges from 0.1 to 0.65, specifically 0.2 or 0.3. When the nickel content of the positive electrode of the ternary lithium battery is greater than or equal to 0.7, the ratio of h1 to h2 ranges from 0.1 to 0.58, specifically 0.3, 0.35, or 0.5.

[0074] When the battery cell is a lithium iron phosphate battery, its positive electrode material is LiFePO4. The lithium iron phosphate may also have doping elements, such as Ti and V. The ratio of h1 to h2 is in the range of 0.2-0.75, specifically 0.3, 0.4 or 0.5.

[0075] When the weak part 601 is a closed structure, the area of ​​the region enclosed by the weak part 601 is S1, such as Figure 8 As shown in the shaded area; when the weak part 601 is a non-closed structure, as... Figure 15 and Figure 17 As shown, the area enclosed by the line connecting the edges of the weak part 601 and the weak part 601 is S1, as... Figure 16 and Figure 18 The shaded area is shown. The area of ​​the region S2-S1 is shown in the figure. Figure 19 , Figure 19 The diagonal area in the diagram represents the area of ​​S1, and the grid line area represents the area between S2 and S1.

[0076] The battery cell of the present invention, by providing a first barrier platform 301 and / or a second barrier platform 302 around the explosion-proof hole 5, or placing a barrier groove 104 with a heat insulation component 7, makes it difficult for the periphery of the explosion-proof valve to melt after the explosion-proof valve opens in the event of thermal runaway, thereby reducing the probability of the flame ejected by the explosion-proof valve burning adjacent battery cells and reducing the occurrence of heat spread.

[0077] In one embodiment, the positive electrode active material is LiNi. 0.6 Co 0.2 Mn 0.2 The manufacturing process of O2 batteries includes the following steps:

[0078] Preparation of the positive electrode: The positive electrode active material LiNi... 0.6 Co 0.2 Mn 0.2O2, conductive agent acetylene black, and binder PVDF are mixed in a mass ratio of 95:3:2. NMP solvent is added, and 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, air-dried at room temperature, and then transferred to an oven for further drying. After cold pressing and slitting, the positive electrode sheet is obtained.

[0079] Preparation of negative electrode sheet: The negative electrode active material graphite, conductive agent acetylene black, thickener CMC and binder SBR are mixed in a mass ratio of 96:1:1.5:1.5, and deionized water is added as 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, dried at room temperature, and then transferred to an oven for further drying. After cold pressing and slitting, the negative electrode sheet is obtained.

[0080] Preparation of electrolyte: Ethyl carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) are mixed in a volume ratio of 1:1:1 to obtain an organic solvent. Then, fully dried lithium salt LiPF6 is dissolved in the mixed organic solvent to prepare an electrolyte with a concentration of 1 mol / L.

[0081] Preparation of the diaphragm: Polyethylene film was selected as the diaphragm;

[0082] Lithium-ion battery preparation: The positive electrode, separator, and negative electrode in the above steps are prepared in sequence through a stacking process, so that the separator is placed between the positive and negative electrode to play a role in isolation. After the battery cell is prepared, the battery cell is put into the casing, the battery cover is welded, and the battery is subjected to processes such as liquid injection, formation, and volume determination.

[0083] Using the above-mentioned LiNi 0.6 Co 0.2 Mn 0.2 The O2 battery was used in the experiment, and the data obtained are shown in Examples 2 to 5, Examples 7 to 12, and Example 14, as well as Comparative Examples 1 and 2 in the table below. Examples 1, 6, 13, and 15 in the table below used LiNi 0.9 Co 0.05 Mn 0.05 O2 batteries were tested, and LiNi 0.9 Co 0.05 Mn 0.05 The preparation steps of O2 batteries are the same as those of LiNi batteries. 0.9 Co 0.05 Mn 0.05 O2 batteries. Examples 16-19 and Comparative Examples 3 and 4 present data obtained from experiments using lithium iron phosphate as the positive electrode active material. The battery capacity Q can be determined by the areal density of the positive electrode sheet, which is between 180-600 g / cm³. 2The thickness of the positive electrode sheet is 80-200 μm; the number of positive electrode sheet layers is controlled between 60-400; the above-mentioned areal density, thickness, and number of positive electrode sheet layers can be comprehensively adjusted in conjunction with capacity, and this application does not impose any limitations.

[0084]

[0085] Performance Test 1: Test for Whether It Triggers Thermal Runaway in Adjacent Batteries: Using a planar or rod-shaped heating device with a ceramic, metal, or insulating layer on its surface, place the heating surface of the device in direct contact with the surface of the individual battery cells. Activate the heating device within 24 hours, heating the target cell at its maximum power. A temperature sensor is placed at the battery's explosion-proof valve location / on the large side (1011) of the battery. In the event of thermal runaway, if the distance between the edge of the explosion-proof valve surface (where the valve is burned) and the edge of the casing is greater than or equal to 3mm, it is considered "no" and will not trigger thermal runaway in adjacent batteries; if it is less than 3mm, it is considered "yes" and will trigger thermal runaway in adjacent batteries. For prismatic batteries, this distance refers to the distance between the sensor and the large side (1011). For cylindrical batteries, this distance refers to the distance between the sensor and the edge of the cylinder.

[0086] Performance Test 2, Weight Loss Rate Test: A planar or rod-shaped heating device, with its surface covered by ceramic, metal, or insulating layers, is used. The heating surface of the device is placed in direct contact with the surface of the battery cell. The heating device is activated within 24 hours and heated to the triggering object at its maximum power. A temperature sensor is placed at the battery explosion-proof valve port / large side of the battery (1011) to calculate the mass before and after thermal runaway. The mass of the battery cell before thermal runaway is m1, and the mass of the battery cell after thermal runaway is m2. The value of (m1-m2) / m1 is obtained. If this value is less than 40%, it is unqualified, indicating that the heat has not been released from the shell and the internal temperature of the shell is too high. If this value is greater than or equal to 40%, it is qualified, and the heat can be smoothly discharged through the explosion-proof valve to avoid excessive heat inside the battery. The thermal runaway triggering conditions are: a) the triggering object experiences a voltage drop, and the drop value exceeds 25% of the initial voltage; b) the temperature at the monitoring point reaches the maximum operating temperature specified by the manufacturer; c) the temperature rise rate at the monitoring point, dT / dt, is ≥1℃ / s and lasts for more than 3s. Thermal runaway is determined to have occurred when either a) and c) or b) and c) occur.

[0087] The present invention also provides a battery pack comprising a plurality of battery cells stacked together, wherein the battery cells are the aforementioned battery cells, and a heat insulation pad is provided between adjacent battery cells, wherein the thickness of the heat insulation pad is 1-5mm, specifically, the thickness of the heat insulation pad can be 1mm, 2.5mm or 4mm.

[0088] In the description of this solution, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this solution, "multiple" means two or more, unless otherwise explicitly specified.

[0089] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0090] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A battery cell, characterized by, The battery includes a battery shell and a battery cell, the battery cell is placed in the battery shell, the battery shell is provided with a burst valve, the burst valve includes a weak part, the battery shell is provided with a blocking part, the blocking part is arranged at the periphery of the weak part, the thickness of the blocking part is greater than the thickness of the weak part, the blocking part includes a blocking body structure, the area surrounded by the weak part is S1, the area surrounded by the outer edge of the blocking part is S2, S1 and S2 satisfy 0.03*10 4 ≤S1*(S2-S1) / (Q*h1 / h2)≤20*10 4 Wherein, Q is the battery capacity, the unit is Ah, h1 is the thickness of the shell provided with the burst valve, the unit is mm, h2 is the thickness sum of the battery shell and the blocking body structure, the unit is mm, the unit of S1 and S2 is mm 2 ; The barrier body structure comprises a barrier platform, which is protrudingly arranged on the outer surface of the battery shell, and the height of the barrier platform is 0.5-3.5mm. The barrier platform is circumferentially arranged on the weak part.

2. The battery cell of claim 1, wherein, In the formula S1*(S2-S1) / (Q*h1 / h2), S1 ranges from 100 to 1200 mm 2 , S2-S1 ranges from 100 to 2850 mm 2 , Q ranges from 20 to 600 Ah, and h1 / h2 ranges from 0.1 to 0.

8.

3. The battery cell of claim 1, wherein, The barrier platform is continuously circumferentially arranged on the weak part, and the range of h1 / h2 is 0.1-0.

7.

4. The battery cell of claim 1, wherein, The width of the barrier platform is 3-50mm.

5. The battery cell of claim 1, wherein, The barrier platform comprises a first barrier platform and a second barrier platform, the first barrier platform is arranged around the weak part, and the first barrier platform is located between the second barrier platform and the weak part.

6. The battery cell of claim 5, wherein, The height ratio of the first barrier platform to the second barrier platform is 0.6-6.

7. The battery cell of claim 5, wherein, The interval distance of the first barrier platform to the second barrier platform is 0-1mm.

8. The battery cell of claim 5, wherein, The first barrier platform is arranged on the second barrier platform close to the weak part, and a protective patch is connected to the surface of the first barrier platform away from the battery cell.

9. The battery cell of claim 1, wherein, The ratio of the height of the barrier platform to the thickness of the battery shell is 0.25-6.

10. The battery cell of claim 1, wherein, The battery shell comprises a shell body and a cover plate, and the explosion-proof valve is arranged on the cover plate.

11. The battery cell of claim 1, wherein, The battery shell comprises a shell body and a cover plate, and the explosion-proof valve is arranged on the shell body.

12. The battery cell of claim 1, wherein, The battery shell is provided with an explosion-proof hole, the explosion-proof valve comprises an explosion-proof sheet, the explosion-proof sheet is connected to the explosion-proof hole, the explosion-proof sheet comprises the weak part, the weak part is continuously arranged in a circle, and the numerical range of h1 / h2 is 0.25-0.

5.

13. The battery cell of claim 1, wherein, The battery shell is provided with an explosion-proof hole, the explosion-proof valve comprises an explosion-proof sheet, the explosion-proof sheet is connected to the explosion-proof hole, the explosion-proof sheet comprises the weak part, the weak part is discontinuously arranged in a circle, and the numerical range of h1 / h2 is 0.3-0.

6.

14. The battery cell of claim 1, wherein, The battery shell is a cylindrical shell, the explosion-proof valve is arranged on the end surface of the cylindrical shell, and the distance between the outer edge of the barrier body structure and the edge of the end surface of the battery shell in the radial direction is 0.5-10mm.

15. The battery cell of claim 1, wherein, The battery shell is a square shell, the battery shell comprises a first surface and a second surface, two first surfaces are oppositely arranged, two of the four second surfaces are oppositely arranged, the area of the first surface is larger than that of the second surface, and the barrier body structure is arranged on the second surface between the two first surfaces.

16. The battery cell of claim 15, wherein, The distance between the barrier body structure and the first surface is 3-20mm, and the barrier body structure is arranged at least at the position close to the first surface of the weak part.

17. The battery cell of claim 1, wherein, The battery monomer is a ternary lithium battery, and the ratio of h1 to h2 is 0.1-0.

65.

18. The battery cell of claim 17, wherein, The nickel content of the positive electrode of the ternary lithium battery is greater than or equal to 0.7, and the ratio of h1 to h2 is 0.1-0.

58.

19. A battery pack comprising a plurality of battery cells stacked together, characterized in that, The battery monomer is the battery monomer of any one of claims 1-18, a heat insulation pad is arranged between adjacent battery monomers, and the thickness of the heat insulation pad is 1-5mm.

Images