Battery pack and its battery cell

Abstract

Battery cell comprising a battery casing and a cell core, wherein the cell core is arranged in the battery casing, wherein an explosion protection valve is arranged on the battery casing, wherein the explosion protection valve comprises a weakened section, wherein a barrier section is arranged on the battery casing, wherein the barrier section is arranged at a periphery of the weakened section, wherein the thickness of the barrier section is greater than the thickness of the weakened section, wherein the barrier section comprises a barrier main structure, wherein an area enclosed by the weakened section is S1 and an area enclosed by an outer edge of the barrier section is S2, wherein S1 and S2 are 0.03*10 4 ≤ S1*(S2-S1) / (Q*h1 / h2) ≤ 20*10 4applies, where Q represents a battery capacity in Ah, h1 represents the thickness of the housing on which the explosion protection valve is arranged in mm, and h2 represents the sum of the thickness of the battery housing and the thickness of the barrier main structure in mm, and where S1 and S2 are in mm 2 are specified.

Description

Technical field

[0001] The present invention relates to the field of battery technology, in particular to a battery pack and its battery cell. Technical background

[0002] A battery thermal runaway refers to an abnormal temperature increase inside the battery, causing chemical reactions within the battery to spiral out of control, ultimately leading to battery failure, fire, or even explosion. During a thermal runaway, the explosion vent opens to dissipate heat. Due to the large amount of heat released, the circumference of the explosion vent melts slightly, and the heat generated by the injected flame is transferred to neighboring battery cells, causing thermal spread and triggering thermal runaway in adjacent batteries. Content of the invention

[0003] In view of this, the present invention provides a battery cell which reduces the probability of combustion of neighboring battery cells during thermal runaway of the battery cell and reduces the occurrence of thermal spread during thermal runaway of a battery.

[0004] The present invention further provides a battery pack.

[0005] To solve the above problem, the present invention provides the following technical solution:

[0006] A battery cell comprising a battery casing and a cell core, wherein the cell core is arranged in the battery casing, wherein an explosion protection valve is arranged on the battery casing, the explosion protection valve comprising a weakened section, wherein a barrier section is arranged on the battery casing, the barrier section being arranged at a periphery of the weakened section, the thickness of the barrier section being greater than the thickness of the weakened section, the barrier section comprising a barrier main structure, wherein an area enclosed by the weakened section is S1 and an area enclosed by an outer edge of the barrier section is S2, wherein S1 and S2 are 0.03*10 4 ≤ S1*(S2-S1) / (Q*h1 / h2) ≤ 20*10 4applies, where Q represents a battery capacity in Ah, h1 represents the thickness of the housing on which the explosion protection valve is arranged in mm, and h2 represents the sum of the thickness of the battery housing and the thickness of the barrier main structure in mm, and where S1 and S2 are in mm 2 are specified.

[0007] It is evident from the above technical solution that in the battery cell provided by the present invention, a barrier section is arranged on the outside of the weakened section of the explosion protection valve, wherein the barrier section is arranged at the periphery of the weakened section and the thickness of the barrier section is greater than the thickness of the weakened section, whereby, in the event that the explosion protection valve releases a large amount of heat, the circumference of the explosion protection valve does not melt easily, thus effectively reducing the risk of melting of the circumference of the explosion protection valve causing the injected flame to burn through to the large surface area of ​​the battery cell, reducing the probability of combustion of adjacent battery cells in the event of thermal runaway of the battery cell, and reducing the occurrence of thermal spread in the event of thermal runaway of the battery.In the battery cell of the present invention, the risk of heat being transferred to adjacent batteries during thermal runaway, and thus triggering thermal runaway in adjacent batteries, is reduced by comprehensively considering the relationship between S1*(S2-S1), Q, and h1 / h2. The value of S1*(S2-S1) / (Q*h1 / h2) must not be too small, because if there is significant heat generation inside the battery, an excessively small value of the above formula leads to poor effectiveness of the barrier section in blocking heat transfer, resulting in an increased risk of thermal runaway in adjacent batteries. Conversely, the value of the above formula must not be too large, as this would reduce the energy density of the battery.

[0008] The present invention further provides a battery pack comprising several battery cells stacked on top of each other, wherein the battery cell is a battery cell as described above, wherein a thermal insulation layer is arranged between adjacent battery cells, and wherein the thermal insulation layer has a thickness of 1 to 5 mm.

[0009] The battery pack of the present invention comprises the battery cell described above and therefore has the advantages of the battery cell described above, which are not described again here. Images

[0010] To more clearly explain the technical solutions in the embodiments of the present invention or in the prior art, the figures necessary for describing the embodiments or the prior art are briefly presented below. Obviously, the figures described below represent only some embodiments of the present invention. The person skilled in the art can derive further figures from these without inventive effort. Fig. Figure 1 shows a schematic structural view of a battery cell according to an embodiment of the present invention from one angle; Fig. 2 shows a schematic structural view of a battery cell according to an embodiment of the present invention from a further perspective; Fig. Figure 3 shows a schematic view of the cross-sectional structure at position AA. Fig. 2; Fig. Figure 4 shows a schematic enlarged structural view of section B from Fig. 3; Fig. Figure 5 shows a schematic structural view in which, according to an embodiment of the present invention, a barrier platform is directly connected to a protective film; Fig. Figure 6 shows a schematic structural view in which, according to an embodiment of the present invention, a first barrier platform is arranged on a barrier platform; Fig. Figure 7 shows a schematic structural view in which, according to an embodiment of the present invention, a barrier platform is connected to the protective film via a first barrier platform; Fig. Figure 8 shows a schematic view of the area of ​​a weakened section of an explosion protection valve according to an embodiment of the present invention; Fig.Figure 9 shows a schematic view of the cross-sectional structure of an explosion protection film according to an embodiment of the present invention; Fig. Figure 10 shows a schematic structural view of the area enclosed by a barrier section according to an embodiment of the present invention; Fig. Figure 11 shows a schematic structural view of a barrier platform according to an embodiment of the present invention; Fig. Figure 12 shows a schematic partial sectional view of the structure at the position of a barrier groove according to an embodiment of the present invention; Fig. Figure 13 shows a schematic structural view of a barrier groove in which a thermal insulation element is arranged, according to an embodiment of the present invention; Fig. Figure 14 shows a schematic view of the cross-sectional structure at position EE. Fig. 13; Fig.Figure 15 shows a schematic structural view of an explosion protection film according to an embodiment of the present invention; Fig. Figure 16 shows a schematic view of the area of ​​the weakened section of the explosion protection valve. Fig. 15; Fig. Figure 17 shows a schematic structural view of an explosion protection film according to a further embodiment of the present invention; Fig. Figure 18 shows a schematic view of the area of ​​the weakened section of the explosion protection valve. Fig. 17; Fig. Figure 19 shows a schematic structural view of the difference between the area enclosed by a barrier section and the area of ​​a weakened section according to a further embodiment of the present invention. Reference symbol list: 1 battery case; 101 Main housing body; 1011 large page; 102 Cover plate; 103 lead; 104 barriers; 2 protective films; 3 Barrier platform; 301 first barrier platform; 302 second barrier platform; 4. Nucleus; 5 Explosion protection openings; 6 explosion protection foil; 601 weakened section; 7 Thermal insulation element. Description of embodiments

[0011] The present invention provides a battery cell that reduces the probability of combustion of neighboring battery cells during thermal runaway of the battery cell and reduces the occurrence of thermal spread during thermal runaway of a battery.

[0012] The present invention further discloses a battery pack.

[0013] The technical solutions in the exemplary embodiments of the present invention are described clearly and completely below in conjunction with the accompanying figures of these embodiments. Obviously, the described exemplary embodiments represent only a subset of the exemplary embodiments of the present invention and do not encompass all possible embodiments. All other exemplary embodiments that could be obtained by a person skilled in the art without inventive effort based on the exemplary embodiments in the present invention are within the scope of protection of the present invention.

[0014] Referring to the Fig. 1, Fig. 2, Fig. 3, Fig. 4, Fig. 5, Fig. 6, Fig. 7, Fig. 8, Fig. 9, Fig. 10, Fig. 11, Fig. 12, Fig. 13 to Fig.14. A battery cell according to the invention comprises a battery housing 1 and a cell core 4. The battery housing 1 is arranged on the outermost side of the cell core 4 to protect the cell core 4. The material of the battery housing 1 can be selected from, but is not limited to, aluminum, steel, and aluminum alloys. Specifically, the material of the battery housing 1 can be an aluminum-manganese alloy, an aluminum-magnesium alloy, stainless steel, nickel-plated steel, carbon steel, or titanium, etc.

[0015] The cell nucleus 4 comprises a positive electrode sheet, a negative electrode sheet, and a separator positioned between them, the positive electrode sheet, the negative electrode sheet, and the separator forming a cell nucleus body when stacked together. The positive electrode sheet comprises a positive electrode current collector and a positive electrode active material. The positive electrode current collector can be made of a metallic material such as aluminum foil, nickel foil, or stainless steel; alternatively, the positive electrode current collector can be a composite foil made of a metal and an insulating material. The positive electrode active material comprises a primary active positive electrode material, a conductor, a binder, etc.The active primary material of the positive electrode comprises one or more lithium-containing active materials such as lithium iron phosphate, ternary materials containing nickel-cobalt-manganese, and lithium manganese iron phosphate. The negative electrode sheet comprises a negative electrode current collector and a negative electrode active material, wherein the negative electrode current collector may be a metallic material such as copper foil, aluminum foil, stainless steel, etc., or may be a composite foil composed of a metal and an insulating material. The active material of the negative electrode comprises a primary active material, a conductor, a binder, etc., wherein the primary active material of the negative electrode comprises one or more synthetic graphite, natural graphite, silicon carbon, silicon oxide, lithium titanate, etc.

[0016] An explosion protection valve is arranged on the battery housing 1. The explosion protection valve comprises a weakened section 601, wherein the weakened section 601 is configured such that, in the event of thermal runaway of the battery, the explosion protection valve ruptures at the location of the weakened section 601 to release the heat, dust, etc., from inside the battery. Specifically, the explosion protection valve can be configured such that an explosion protection opening 5 is provided on the battery housing 1, wherein the explosion protection valve comprises an explosion protection film 6, and the explosion protection film 6 is connected to the explosion protection opening 5. The weakened section 601 on the explosion protection valve can be a thinned area on the explosion protection film 6, wherein the weakened section 601 can be arranged circumferentially or non-circumferentially and spaced apart to prevent ejection of the explosion protection film 6.

[0017] The weakened section 601 can be formed directly on the explosion protection film 6 by stamping or laser etching, and the weakened section 601 also features a grooved structure. In this structure, a groove is first formed, and then a groove is formed within the groove by laser etching. The explosion protection valve comprises the weakened section 601, with a barrier section arranged on the battery housing 1, the barrier section being located at the periphery of the weakened section 601. The periphery here refers to a side located away from the center of the explosion protection film 6. The barrier section serves to improve the heat resistance of the circumference of the explosion protection valve. The thickness of the barrier section is greater than the thickness of the weakened section 601, thereby improving the melt resistance around the explosion protection valve.The barrier section comprises a main barrier structure, with the area enclosed by the weakened section 601 being S1, as shown in . Fig. 8 shown. The area enclosed by the outer edge of the barrier section is S2, as shown in Fig. 10 shown, so that the effective area of ​​the barrier section S2-S1 is, where for S1 and S2 0.03*10 4 ≤ S1*(S2-S1) / (Q*h1 / h2) ≤ 20*10 4 applies, where a specific value is 0.03*10 4 , 0.1*10 4 , 2*10 4 or 5*10 4 can be selected. Here, Q represents a battery capacity in Ah, h1 represents a thickness of the battery housing 1 on which the explosion protection valve is arranged, in mm, and h2 represents the sum of the thickness of the battery housing 1 and the thickness of the barrier main structure in mm, where S1 and S2 are in mm. 2 are specified.

[0018] To increase the battery's energy density and achieve a larger battery capacity, the amount of heat and gas generated during thermal runaway increases. When batteries are stacked in a pack and one battery experiences thermal runaway, thermal propagation can easily trigger thermal runaway in adjacent batteries. In the battery cell of the present invention, the relationship between the area of ​​the barrier section, the area of ​​the weakened section 601, the battery capacity, and the ratio of the barrier main structure thickness to the casing wall thickness is adjusted by comprehensive control of the relationship between the aforementioned parameters.By positioning the barrier section, heat transfer to neighboring batteries is prevented, thermal spread is reduced, and the triggering of thermal runaway in neighboring batteries is avoided; at the same time, an impairment of the battery's energy density is also avoided.

[0019] In the battery cell of the present invention, a barrier section is arranged on the outside of the weakened section 601 of the explosion protection valve, wherein the barrier section is arranged at the periphery of the weakened section 601 and the thickness of the barrier section is greater than the thickness of the weakened section 601, whereby, in the event that the explosion protection valve releases a large amount of heat, the circumference of the explosion protection valve does not melt easily, thus effectively reducing the risk that melting of the circumference of the explosion protection valve causes the injected flame to burn through to the large surface of the battery cell, reducing the probability of combustion of adjacent battery cells in the event of thermal runaway of the battery cell and reducing the occurrence of thermal spread in the event of thermal runaway of the battery.In the battery cell of the present invention, the risk of heat being transferred to adjacent batteries during thermal runaway, and thus triggering thermal runaway in adjacent batteries, is reduced by comprehensively considering the relationship between S1*(S2-S1), Q, and h1 / h2. The value of S1*(S2-S1) / (Q*h1 / h2) must not be too small, because if there is significant heat generation inside the battery, an excessively small value of the above formula leads to poor effectiveness of the barrier section in blocking heat transfer, resulting in an increased risk of thermal runaway in adjacent batteries. Conversely, the value of the above formula must not be too large.If the value of the above formula is too large, the arranged barrier section will be too large due to the fixed intake space inside the battery pack, which leads to a reduction in the placement space for the cell core and impairs the interior of the battery; an insufficient interior space leads to the gas ejection being hindered, heat and gases easily accumulating inside the battery housing 1 and not being able to be dissipated smoothly, which means that in the event of thermal runaway the mass loss rate of the battery does not meet the requirements and the heat and gases are not dissipated in time.

[0020] A battery pack typically consists of several battery cells grouped together. When battery cells are grouped into a pack, the large surface areas of adjacent battery cells are arranged close to each other. The large surface area of ​​a battery cell refers to the side of the battery cell with the largest area.

[0021] In one embodiment, S1 lies in a range of 100 to 1200 mm. 2 and can specifically be 200 mm 2 , 500 mm 2 or 800 mm 2 are; where S2-S1 is in a range of 100 to 2850 mm 2 lies and specifically 200 mm 2 , 400 mm 2 or 1000 mm 2Q can be in a range of 20 to 600 Ah and can be specifically 30 Ah, 100 Ah, or 200 Ah; h1 / h2 can be in a range of 0.1 to 0.8 and can be specifically 0.2, 0.3, or 0.5. Controlling the range of S1 and the range of (S2-S1) further reduces the risk of heat propagation to adjacent batteries during a thermal runaway. Controlling the range of Q takes into account the battery's energy density and reduces the risk of triggering a thermal runaway in adjacent batteries when a thermal runaway occurs.Further control of the h1 / h2 range prevents heat from being transferred to neighboring batteries during thermal runaway and triggering thermal runaway in neighboring batteries; at the same time, it prevents the interior of the battery and a gas outlet channel from being affected, ensuring that heat and gases cannot be dissipated smoothly during thermal runaway and that heat does not accumulate inside the casing.

[0022] The main barrier structure comprises a barrier platform 3, as shown in Fig. 1, Fig. 4 and Fig.Figure 5 shows that the barrier platform 3 is arranged protruding from the outer surface of the battery housing 1. By arranging the barrier platform 3, the thickness around the explosion protection opening 5 is increased to reduce combined thermal propagation of the battery during thermal runaway. The barrier platform 3 is arranged at least at one position of the explosion protection valve that is close to a large-area side 1011 of the battery housing 1, as shown in Figure 5. Fig. Figure 6 shows the large-area side 1011 of the battery housing 1. This refers to a side surface of the battery housing 1 with the largest area. When several battery cells are grouped into a pack, the large-area sides 1011 of adjacent battery cells are in contact with each other or are spaced apart by a thermal insulation layer.

[0023] Furthermore, the barrier platform 3 is arranged around the weakened section 601. In one embodiment, the barrier platform 3 continuously surrounds the weakened section 601. This continuous surrounding means that the barrier platform 3 is arranged continuously along the circumference, as shown in Fig.Figure 6 shows the following embodiment. In this embodiment, h1 / h2 lies in a range of 0.1 to 0.7, where h1 / h2 can be 0.3 or 0.4. By continuously arranging the barrier platform 3 around the weakened section 601, the blocking effect of the barrier platform 3 on the heat is improved. h1 / h2 is further controlled in the range of 0.1 to 0.7 to reduce the space occupied by the battery housing 1 by the arrangement of the barrier platform 3 and to avoid any impairment of the ventilation space inside the battery housing 1 as well as any impairment of the smooth pressure relief of the explosion protection valve.

[0024] In another embodiment, several barrier platforms 3 are provided, wherein the multiple barrier platforms 3 are spaced apart from one another around the weakened section 601, i.e., the barrier platforms 3 are arranged discontinuously around their circumference. The spaced arrangement of the barrier platforms 3 reduces the weight of the barrier platforms 3 and thus reduces the overall weight of the housing, which contributes to increasing the energy density of the battery. However, since the barrier platforms 3 are arranged discontinuously, the blocking effect on heat is weakened. By controlling the h1 / h2 range, the risk of triggering thermal runaway in adjacent batteries is further reduced. As in Fig. As shown in Figure 11, the range of h1 / h2 in this embodiment is 0.3 to 0.8, where h1 / h2 can be 0.3, 0.4 or 0.7.

[0025] Accordingly, the weakened section 601 on the explosion protection film 6 can be arranged continuously or discontinuously. If the weakened section 601 is arranged continuously, that is, if the thinned area of ​​the weakened section 601 is arranged continuously along the circumference so that the thinned area forms a closed shape, then h1 / h2 is now in a numerical range of 0.25 to 0.5 and can specifically be 0.25, 0.35, or 0.4. The weakened section 601 can also be arranged discontinuously around its circumference, that is, there are some undiluted areas within the weakened section 601 to avoid the risk of the area of ​​the explosion protection film 6 within the weakened section 601 being ejected and heating adjacent batteries, thereby reducing the probability of thermal runaway.In this case, h1 / h2 lies in a numerical range of 0.3 to 0.6 and can specifically be 0.35, 0.4 or 0.5.

[0026] Specifically, the spacing between adjacent barrier platforms 3 is 1 to 10 mm, and the spacing between adjacent barrier platforms 3 can be 3 mm, 5 mm, or 8 mm. The spacing between adjacent barrier platforms 3 must not be too large; if it is too large, the risk of heat escaping from the gaps in the barrier platforms 3 and affecting adjacent batteries is increased. If the spacing of the barrier platforms 3 is too small and the barrier platforms 3 are arranged too closely together, this also leads to an increase in the weight of the battery housing 1 and impairs the energy density of the battery. The width of the barrier platform 3 is 3 to 50 mm. Specifically, the width of the barrier platform 3 is 5 mm, 15 mm, or 40 mm. The width of the barrier platform 3 refers to the distance between two side faces of the barrier platform 3 that are located near or away from the weakened section 601.

[0027] To improve heat resistance performance, barrier platform 3 comprises a first barrier platform 301 and a second barrier platform 302, as shown in Fig. Figure 6 shows the first barrier platform 301 arranged around the weakened section 601, and the first barrier platform 301 is located between the second barrier platform 302 and the weakened section 601. The height ratio of the first barrier platform 301 to the wider barrier platform 302 is 0.6 to 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.

[0028] Furthermore, the distance between the first barrier platform 301 and the second barrier platform 302 is 0 to 1 mm. If the distance between the first barrier platform 301 and the second barrier platform 302 is 0 mm, the first barrier platform 301 and the second barrier platform 302 are arranged adjacent to each other, as shown in Fig. Figure 7 shows that if the distance between the first barrier platform 301 and the second barrier platform 302 is greater than 0 mm, the first barrier platform 301 and the second barrier platform 302 are spaced apart, with the distance between the first barrier platform 301 and the second barrier platform 302 being 0.5 mm.

[0029] In one embodiment, the first barrier platform 301 is arranged at a position of the second barrier platform 302 close to the weakened section 601, wherein the first barrier platform 301 is arranged around the weakened section 601, and wherein a protective film 2 is attached to the surface of the first barrier platform 301 furthest from the second barrier platform 302. In this embodiment, the first barrier platform 301, the second barrier platform 302, and the battery housing 1 can form a single-piece structure, as shown in Fig. Figure 7 shows that they can be separate structures; alternatively, they can be separate structures. If the barrier platform 3 and the battery housing 1 are separate structures, the barrier platform 3 is glued or welded to the battery housing 1.

[0030] In another embodiment, the barrier platform 3 does not include the first barrier platform 301, but only the second barrier platform 302, as shown in Fig. 5 shown, wherein the second barrier platform 302 is arranged circumferentially on a side of the explosion protection opening 5 away from the explosion protection foil 6, as in Fig. 1 and Fig. 2 shown. As in the Fig. 4 and Fig. As shown in Figure 5, the thickness around the explosion protection opening 5 is increased by arranging the protruding second barrier platform 302 on the outside of the explosion protection opening 5. A protective film 2 is arranged at one end of the explosion protection opening 5, the protective film 2 being bonded to one end of the second barrier platform 302 to protect the explosion protection film 6 and to prevent foreign bodies from entering the explosion protection opening 5.

[0031] In another embodiment, the barrier platform 3 is arranged only at a position of the explosion protection opening 5 located near the large-area side 1011 of the battery cell, as shown in Fig. Figure 11 shows that two barrier platforms 3 are provided, wherein the two barrier platforms 3 are arranged at a position of the weakened section 601 near the large-area side 1011 of the battery cell, thereby increasing the thickness of the explosion protection valve near the large-area side 1011 to reduce the risk of ignition of adjacent battery cells in the event of thermal runaway of the battery cell.

[0032] To facilitate the arrangement of a circumferential structure of the barrier platform 3 with a uniform width, the width D1 of the barrier platform 3 is no greater than the distance from the explosion protection opening 5 to the large-area side 1011 of the battery housing 1. In one embodiment, the width D1 of the barrier platform 3 is less than the distance from the explosion protection opening 5 to the large-area side 1011 of the battery housing 1; that is, the distance D2 from the barrier platform 3 to the large-area side 1011 of the battery cell is greater than zero to facilitate the shaping of the barrier platform 3.

[0033] The ratio of the height of barrier platform 3 to the thickness of battery casing 1 is 0.25 to 6 and can specifically be 0.3, 1, or 4. The height of barrier platform 3 is 0.5 to 3.5 mm and can be 1 mm, 2 mm, or 3 mm; the wall thickness of battery casing 1 is 0.5 to 3 mm and can be 1 mm, 1.5 mm, or 2.5 mm. The ratio of the thickness of barrier platform 3 to the thickness of battery casing 1 must not be too large. Since the internal space within the battery pack is fixed, an excessively large barrier platform 3 reduces the available space for the cell core. If this ratio is too small, the thermal runaway insulation will be compromised.

[0034] In a further embodiment, the main barrier structure is arranged to project from the surface of the battery housing 1 facing the cell core 4 in order to form a barrier groove 104, wherein the barrier groove 104 is provided on the outer surface of the battery housing 1, wherein the main barrier structure comprises the barrier groove 104, that is, the barrier groove 104 is arranged on the surface of the main barrier structure furthest from the cell core 4, and wherein a thermal insulation element 7 is arranged in the barrier groove 104. The barrier groove 104 projects towards the side of the battery housing 1 closest to the cell core 4, as shown in Fig. Figure 14 shows how the arrangement of the structure of the barrier groove 104 reduces the influence of the structural strength of the battery housing 1. Referring to Fig. 12, Fig. 13 to Fig.In section 14, the barrier groove 104 is arranged around the weakened section 601. In particular, the barrier groove 104 is arranged around the explosion protection opening 5. By arranging the structure on the battery housing 1, in which the barrier groove 104 is arranged around the explosion protection opening 5, heat conduction upon activation of the explosion protection valve can be effectively reduced, the impact on the large-area side 1011 of the battery cell upon activation of the explosion protection valve can be reduced, and the risk of melting of the large-area side 1011 can be reduced.The thermal insulation element 7 is arranged in the barrier groove 104, and the thermal insulation element 7 is filled into the barrier groove 104, which further reduces heat conduction when the explosion protection valve is triggered, greatly reduces the risk of outward propagation when the explosion protection valve melts, and effectively prevents the heat released when the explosion protection valve is triggered from affecting the structures of the battery housing 1 located away from the explosion protection valve. Furthermore, a first barrier platform 301 is arranged around the explosion protection opening 5.

[0035] In one embodiment, the barrier groove 104 is a groove structure punched out of the battery housing 1, wherein the barrier groove 104 forms a projection 103 that protrudes towards the side of the battery housing 1 located near the cell core 4, as shown in Fig. 12 and Fig.14 shown, where the numerical value of the height D3 of the projection 103 is equal to that of the groove depth D5 of the barrier groove 104.

[0036] Furthermore, the groove depth of the barrier groove 104 is 0.5 to 3.5 mm and can be specifically 1.5 mm, 2.5 mm, or 3 mm. To ensure the structural strength of the battery housing 1, the groove depth of the barrier groove 104 must not be too great. An excessive groove depth requires more space inside the battery housing 1, impairs the removal of internal gases, and, in the event of thermal runaway, hinders the dissipation of heat and gases, leading to heat accumulation inside the battery housing 1. To achieve good thermal insulation, the groove depth of the barrier groove 104 must also not be too shallow. The groove width of the barrier groove 104 is 3 to 50 mm. The groove width of the barrier groove 104 is 5 mm, 15 mm, or 40 mm. The groove width of the barrier groove 104 refers to a distance between two groove side surfaces of the barrier groove 104, which are located near or away from the weakened section 601.If the barrier groove 104 is too narrow, it is not easy to block heat conduction through it. Conversely, if the barrier groove 104 is too wide, it leads to a greater weakening of the structural strength of the battery housing 1.

[0037] The melting point of the thermal insulation element 7 is higher than the melting point of the battery casing 1, so that if the battery casing 1 melts around the weakened section 601, the thermal insulation element 7 can maintain its shape to prevent the battery casing 1 from melting and to avoid further spread of the melting. The melting point of the thermal insulation element 7 is greater than or equal to 700°C.

[0038] Specifically, the battery housing 1 comprises a housing main body 101 and a cover plate 102, wherein the housing main body 101 is a rectangular housing, the cell core 4 is placed in a cavity of the housing main body 101, and the cover plate 102 is connected to a position of an upper opening of the housing main body 101. If the battery housing 1 is a square housing, the battery housing 1 comprises first surfaces and second surfaces, wherein the number of first surfaces is two, the two first surfaces being opposite each other, and the four second surfaces being arranged in pairs, the area of ​​the first surface being larger than the area of ​​the second surface, and the barrier main structure being located on the second surface between the two first surfaces. The first surface here refers to the large-area side 1011 mentioned above.The distance between the main barrier structure and the large-area side 1011 is 3 to 20 mm, with the main barrier structure being located at least at a position of the weakened section 601 close to the large-area side 1011. Specifically, the distance between the main barrier structure and the large-area side 1011 is 4 mm, 10 mm, or 15 mm. Controlling the distance between the main barrier structure and the large-area side 1011 prevents the main barrier structure from being located too close to the edge, which would make it difficult to shape. It also prevents the main barrier structure from being too far away, which would result in an insufficient width of the main barrier structure and thus impair the blocking of heat transfer. In one embodiment, the explosion protection valve is arranged on the cover plate 102, as shown in [reference]. Fig.Figure 6 shows. In a further embodiment, the explosion protection valve is arranged on the main housing body 101.

[0039] In other embodiments, the battery housing 1 can also be a cylindrical housing, wherein the explosion protection valve is arranged on an end face of the cylindrical housing, and wherein the radial distance between the outer edge of the barrier main structure and the edge of the end face of the battery housing 1 is 0.5 to 10 mm. In one embodiment, the distance between the barrier main structure and the edge of the end face of the battery housing 1 is 1 mm, 4 mm, or 6 mm.

[0040] There are different types of lithium batteries. When the battery cell is a ternary lithium battery, the term "ternary lithium battery" specifically refers to a ternary nickel-cobalt-manganese or ternary nickel-cobalt-aluminum material. The ternary structure of a ternary lithium battery is LiNi. x Co y Mn zO2, where 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; in addition, a doping element M may be present, where element M is Zr, Ti, Si, Mo, La, Ce, Te, Nb, Ta, Si, Al, W, Sr, V, Y, Mg, Co, F, Cl, S, L. If the battery cell is a ternary lithium battery, the h1 to h2 ratio is in the range of 0.1 to 0.65 and may be specific 0.2 or 0.3. If the positive electrode of the ternary lithium battery has a nickel content greater than or equal to 0.7, the h1 to h2 ratio is in the range of 0.1 to 0.58, specifically 0.3, 0.35, or 0.5.

[0041] If the battery cell is a lithium iron phosphate battery, the material of its positive electrode is LiFePO4, wherein the lithium iron phosphate may also contain dopants, wherein the dopant may be Ti, V, and wherein the ratio of h1 to h2 is in a range of 0.2 to 0.75, specifically at 0.3, 0.4 or 0.5.

[0042] If the weakened section 601 represents a closed structure, the area of ​​a region S1 enclosed by the weakened section 601, as shown by the shaded part in Fig. 8 shown. If the weakened section 601 is a non-closed structure, as in Fig. 15 and Fig. As shown in Figure 17, the area of ​​a region S1 enclosed by the edge connecting line of the weakened section 601 and the weakened section 601, as represented by the shaded part in the Fig. 16 and Fig.18 shown. The area of ​​the S2-S1 region is in Fig. 19 can be seen, with the hatched area in Fig. 19 the area of ​​S1, and the grid-like area is the region of S2-S1.

[0043] The battery cell of the present invention, by arranging the first barrier platform 301 and / or the second barrier platform 302 around the explosion protection opening 5 or the barrier groove 104 with a thermal insulation element 7 placed therein, ensures that after opening the explosion protection valve during thermal runaway, the circumference of the explosion protection valve does not melt easily, thereby reducing the probability of combustion of adjacent battery cells by the flame injected by the explosion protection valve and reducing the occurrence of thermal spread.

[0044] In one embodiment, a manufacturing process for a battery with an active material of a positive electrode LiNi comprises 0,6 Co 0,2 Mn 0,2 O2 the following steps:

[0045] Manufacturing a positive electrode sheet: The active material of the positive electrode is LiNi. 0,6 Co 0,2 Mn 0,2O2, acetylene carbon black as a conductor, and PVDF as a binder are mixed in a mass ratio of 95:3:2. NMP is then added as a solvent, and the resulting mixture is stirred under vacuum mixing until homogeneous to obtain a positive electrode slurry. The positive electrode slurry is applied evenly to two surfaces of an aluminum foil current collector of the positive electrode, dried at room temperature, then transferred to an oven for further drying, and subsequently cold-pressed and cut to obtain a positive electrode sheet.

[0046] To produce a negative electrode sheet: Graphite as the active material of the negative electrode, carbon black as a conductor, CMC as a thickener, and SBR as a binder are mixed in a mass ratio of 96:1:1.5:1.5. Deionized water is added as a solvent, and the resulting mixture is stirred under vacuum mixing until homogeneous to obtain a negative electrode slurry. The negative electrode slurry is applied evenly to two surfaces of a copper foil current collector of the negative electrode, dried at room temperature, then transferred to an oven for further drying, and subsequently cold-pressed and cut to obtain a negative electrode sheet.

[0047] Preparation of an electrolyte: Ethylene 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. Subsequently, a fully dried lithium salt LiPF6 is dissolved in the mixed organic solvent to prepare an electrolyte with a concentration of 1 mol / L.

[0048] Manufacturing a separator. A polyethylene film is selected as the separator;

[0049] Manufacturing a lithium-ion battery: The positive electrode sheet, separator, and negative electrode sheet from the steps above are prepared sequentially through a stacking process, with the separator positioned between the positive and negative electrode sheets to provide insulation. After the formation of a cell core, the core is inserted into a casing, and the battery's cover plate is welded on. The battery then undergoes processes such as liquid injection, conditioning, and capacity determination.

[0050] The LiNi 0,6 Co 0,2 Mn 0,2 The O2 battery described above is used for experiments. The data obtained are presented in the following table for embodiments 2 to 5, embodiments 7 to 12, embodiment 14, and comparative examples 1 and 2. In embodiments 1, 6, 13, and 15 in the following table, a LiNi battery is used.0,9 Co 0,05 Mn 0,05 O2 battery used for experiments. The steps for making a LiNi 0,9 Co 0,05 Mn 0,05 The steps for manufacturing an O2 battery are the same as those for a LiNi battery. 0,9 Co 0,05 Mn 0,05 O2 battery. In embodiments 16-19 and comparative examples 3-4, data are presented that were obtained from experiments using a battery in which lithium iron phosphate is selected as the active material of the positive electrode. A battery capacity Q can be achieved by an areal density of the positive electrode sheet of 180 to 600 g / cm². 2The thickness of the positive electrode sheet can be regulated from 80 to 200 µm, and the number of layers of the positive electrode sheet from 60 to 400. Regarding the restrictions on the areal density, the thickness of the positive electrode sheet, and the number of layers of the positive electrode sheet mentioned above, comprehensive regulation in combination with the capacity is possible, which is not restricted in the present application. Nr . S1 S2-S1 Q h1 / h2 S1*(S2-S1) / (Q*h1 / h2) Performance 1 Performance 2 Ternary-LiNi 0,9 Co 0,05 Mn 0,05 O2 Example 1 1196,8 2803,2 183 0,8 2,29*10 4 No qualified Ternary-LiNi 0,6 Co 0,2 Mn 0,2 O2 Example 2 1189,4 120,6 125 0,5 0,23*10 4 No qualified Ternary-LiNi 0,6 Co 0,2 Mn 0,2 O2 Example 3 1185,2 614,8 125 0,7 0,83*10 4 No qualified Ternary-LiNi 0,6 Co 0,2 Mn 0,2 O2 Example 4 1170,8 629,2 145 0,2 2,54*10 4 No qualified Ternary-LiNi 0,6 Co 0,2 Mn 0,2 O2 Example 5 1198,8 2801,2 50 0,34 19,75*10 4 No qualified Ternary-LiNi 0,9 Co 0,05 Mn 0,05 O2 Example 6 1186,8 2813,2 597 0,7 0,8*10 4 No qualified Ternary-LiNi 0,6 Co 0,2 Mn 0,2 O2 Example 7 105,6 100,4 86 0,4 0,03*10 4 No qualified Ternary-LiNi 0,6 Co 0,2 Mn 0,2 O2 Example 8 100,4 299,6 86 0,12 0,29*10 4 No qualified Ternary-LiNi 0,6 Co 0,2 Mn 0,2 O2 Example 9 104,5 95,5 23 0,8 0,05*10 4 No qualified Ternary-LiNi 0,6 Co 0,2 Mn 0,2 O2 Example 10 634,5 389,5 95 0,4 0,65*10 4 No qualified Ternary-LiNi 0,6 Co 0,2 Mn 0,2 O2 Example 11 624,9 399,1 136 0,2 0,92*10 4 No qualified Ternary-LiNi 0,6 Co 0,2 Mn 0,2 O2 Example 12 1154,8 2005,2 78 0,3 9,9*10 4 No qualified Ternary-LiNi 0,9 Co 0,05 Mn 0,05 O2 Example 13 1164,6 1995,4 368 0,32 1,97*10 4 No qualified Ternary-LiNi 0,6 Co 0,2 Mn 0,2 O2 Example 14 81,2 98,8 25 0,08 0,4*10 4 No qualified Ternary-LiNi 0,9 Co 0,05 Mn 0,05 O2 Example 15 1298,8 3001,2 368 0,35 3,03*10 4 No qualified Ternary-LiNi 0,6 Co 0,2 Mn 0,2 O2 Comparative example 1 104,3 101,7 125 0,38 0,02*10 4 Yes qualified Ternary-LiNi 0,6 Co 0,2 Mn 0,2 O2 Comparative example 2 1186,8 2813,2 136 0,11 22,32*10 4 No unqualified Lithium iron phosphate Example 16 1188,8 2811,2 124 0,8 3,37*10 4 No qualified Example 17 104,6 101,4 82 0,4 0,03*10 4 No qualified Example 18 1169,8 2830,2 50 0,34 19,48*10 4 No qualified Example 19 79,2 100,8 25 0,08 0,4*10 4 No qualified Comparative example 3 107,9 98,1 124 0,38 0,02*10 4 Yes qualified Comparative example 4 1180,6 2819,4 136 0,11 22,25*10 4 No unqualified

[0051] Performance Test 1 “Test to determine whether thermal runaway of adjacent batteries is triggered”: A planar or rod-shaped heating device is used, and its surface is to be covered with a ceramic, metal, or insulating layer; the heating surface of the device is brought into direct contact with the surface of the battery cell; the heating device is started within 24 hours, and a trigger object is heated at the maximum power of the device. A temperature sensor is placed at the location of the battery's explosion protection valve / at the location of the large-area side 1011 of the battery.If thermal runaway occurs and the distance between the edge of the burned area on the surface of the explosion protection valve provided on the housing and the edge of the housing is greater than or equal to 3 mm, this is evaluated as "No," meaning that no thermal runaway of adjacent batteries is triggered; if this distance is less than 3 mm, this is evaluated as "Yes," meaning that thermal runaway of adjacent batteries is triggered. For a square battery, the distance here refers to the distance to the large-area side of the battery. For a cylindrical battery, the distance here refers to the distance to the edge of the cylinder.

[0052] Performance Test 2 “Mass Loss Rate Test”: A planar or rod-shaped heating device is used, and its surface is to be covered with a ceramic, metal, or insulating layer; the heating surface of the device is brought into direct contact with the surface of the battery cell, the heating device is started within 24 hours, and the trigger object is heated at the maximum power of the device. A temperature sensor is placed at the opening of the battery's explosion protection valve / on the large-area side 1011 of the battery, and the mass before and after the occurrence of thermal runaway is calculated, where the mass of the battery cell before thermal runaway is m1 and the mass of the battery cell after thermal runaway is m2, where the value of (m1-m2) / m1 is obtained.If this value is less than 40%, it is considered unqualified, as no heat is dissipated from the casing and the temperature inside the casing is too high. If this value is greater than or equal to 40%, it is considered qualified, as the heat can be dissipated smoothly through the explosion protection valve, thus preventing the temperature inside the battery from becoming too high. The assessment criteria for triggering thermal runaway are: a) The triggering object produces a voltage drop whose 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 dT / dt at the monitoring point is ≥ 1 °C / s and lasts for more than 3 seconds. If a) and c) or b) and c) occur, thermal runaway is determined to have occurred.

[0053] The present invention further provides a battery pack comprising several battery cells stacked on top of each other, wherein the battery cell is a battery cell as described above, wherein a thermal insulation layer is arranged between adjacent battery cells, wherein the thickness of the thermal insulation layer is 1-5 mm, and specifically the thickness of the thermal insulation layer can be 1 mm, 2.5 mm or 4 mm.

[0054] In describing the present solution, it should be understood that the terms "first" and "second" serve only descriptive purposes and are not to be understood as an implicit or explicit indication of the relative importance or the number of the feature in question. Thus, the features defined as "first" and "second" can explicitly or implicitly include one or more of these features. In the description of this solution, "plural" is understood to mean two or more than two, unless explicitly defined otherwise.

[0055] The various embodiments described in this document are presented progressively. Each embodiment focuses on its differences from the others. Identical or similar parts between the different embodiments can be related to one another.

[0056] The above explanation of the disclosed embodiments enables a person skilled in the art to implement or use the present invention. Various modifications to these embodiments are obvious to a person skilled in the art. The general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments presented herein, but should correspond to the broadest scope consistent with the principles and novel features disclosed herein.

[0057] The present invention discloses a battery cell comprising a battery housing and a cell core, wherein the cell core is arranged in the battery housing, wherein an explosion protection valve is arranged on the battery housing, wherein the explosion protection valve comprises a weakened section, wherein a barrier section is arranged on the battery housing, wherein the barrier section is arranged at a periphery of the weakened section, wherein the thickness of the barrier section is greater than the thickness of the weakened section, wherein the barrier section comprises a barrier main structure, wherein an area enclosed by the weakened section is S1 and an area enclosed by an outer edge of the barrier section is S2, wherein S1 and S2 are 0.03*10 4 ≤ S1*(S2-S1) / (Q*h1 / h2) ≤ 20*10 4where Q represents a battery capacity, h1 represents the thickness of the housing on which the explosion protection valve is arranged, and h2 represents the sum of the thickness of the battery housing and the thickness of the barrier main structure. The battery cell of the present invention reduces the probability of combustion of adjacent battery cells during thermal runaway and reduces the occurrence of thermal spread during thermal runaway of a battery. The present invention further discloses a battery pack

Claims

A battery cell comprising a battery casing and a cell core, wherein the cell core is arranged in the battery casing, wherein an explosion protection valve is arranged on the battery casing, the explosion protection valve comprising a weakened section, wherein a barrier section is arranged on the battery casing, the barrier section being arranged at a periphery of the weakened section, the thickness of the barrier section being greater than the thickness of the weakened section, the barrier section comprising a barrier main structure, wherein an area enclosed by the weakened section is S1 and an area enclosed by an outer edge of the barrier section is S2, wherein for S1 and S2 0.03*104≤ S1*(S2-S1) / (Q*h1 / h2) ≤ 20*104 holds, where Q is a battery capacity in Ah, h1 is the thickness of the casing on which the explosion protection valve is arranged.in mm and h2 represents the sum of the thickness of the battery casing and the thickness of the barrier main structure in mm, and where S1 and S2 are specified in mm2. Battery cell according to claim 1, characterized in that in the formula S1*(S2-S1) / (Q*h1 / h2) S1 is in a range of 100 to 1200 mm2, S2-S1 is in a range of 100 to 2850 mm2, Q is in a range of 20 to 600 Ah and h1 / h2 is in a range of 0.1 to 0.

8. Battery cell according to claim 1, characterized in that the main barrier structure comprises a barrier platform, wherein the barrier platform is arranged protruding on an outer surface of the battery housing. Battery cell according to claim 3, characterized in that the barrier platform is arranged circumferentially on the weakened section. Battery cell according to claim 4, characterized in that the barrier platform continuously surrounds the weakened section, wherein h1 / h2 is in a range of 0.1-0.

7. Battery cell according to claim 4, characterized in that several barrier platforms are provided, wherein the several barrier platforms are arranged spaced apart from each other around the weakened section, wherein h1 / h2 lies in a range of 0.3 to 0.

8. Battery cell according to claim 6, characterized in that the distance between adjacent barrier platforms is 1 to 10 mm. Battery cell according to claim 3 or 4, characterized in that the barrier platform has a width of 3 to 50 mm. Battery cell according to claim 3 or 4, characterized in that the barrier platform comprises a first barrier platform and a second barrier platform, wherein the first barrier platform is arranged around the weakened section, and wherein the first barrier platform is located between the second barrier platform and the weakened section. Battery cell according to claim 9, characterized in that the height ratio of the first barrier platform to the second barrier platform is 0.6 to 6. Battery cell according to claim 9, characterized in that the distance between the first barrier platform and the second barrier platform is 0 to 1 mm. Battery cell according to claim 9, characterized in that the first barrier platform is arranged at a position of the second barrier platform close to the weakened section, wherein a protective film is attached to a surface of the first barrier platform away from the cell core. Battery cell according to claim 3 or 4, characterized in that the ratio of the height of the barrier platform to the thickness of the battery housing is 0.25 to 6. Battery cell according to claim 3 or 4, characterized in that the barrier platform and the battery housing form a one-piece structure. Battery cell according to claim 3 or 4, characterized in that the barrier platform and the battery housing are separate structures, wherein the barrier platform is connected to the battery housing. Battery cell according to claim 1, characterized in that the main barrier structure is designed to project from the battery housing towards the cell core in order to form a barrier groove, wherein the barrier groove is provided on the outer surface of the battery housing, and wherein a thermal insulation element is arranged in the barrier groove. Battery cell according to claim 16, characterized in that the barrier groove is arranged around the weakened section. Battery cell according to claim 16, characterized in that the barrier groove has a groove depth of 0.5 to 3.5 mm and a groove width of 3 to 50 mm. Battery cell according to claim 16, characterized in that the melting point of the thermal insulation element is higher than the melting point of the battery housing, wherein the melting point of the thermal insulation element is greater than or equal to 700°C. Battery cell according to claim 1, characterized in that the battery housing comprises a housing main body and a cover plate, wherein the explosion protection valve is arranged on the cover plate. Battery cell according to claim 1, characterized in that the battery housing comprises a housing main body and a cover plate, wherein the explosion protection valve is arranged on the housing main body. Battery cell according to claim 2, characterized in that an explosion protection opening is provided on the battery housing, wherein the explosion protection valve comprises an explosion protection film, wherein the explosion protection film is connected to the explosion protection opening, wherein the explosion protection film comprises the weakened section, wherein the weakened section is arranged continuously around its circumference, and wherein h1 / h2 is in a numerical range of 0.25 to 0.

5. Battery cell according to claim 2, characterized in that an explosion protection opening is provided on the battery housing, wherein the explosion protection valve comprises an explosion protection film, wherein the explosion protection film is connected to the explosion protection opening, wherein the explosion protection film comprises the weakened section, wherein the weakened section is arranged discontinuously around its circumference, and wherein h1 / h2 lies in a numerical range of 0.3 to 0.

6. Battery cell according to claim 1, characterized in that the battery housing is a cylindrical housing, wherein the explosion protection valve is arranged on an end face of the cylindrical housing, wherein in the radial direction a distance between an outer edge of the barrier main structure and an edge of the end face of the battery housing is 0.5 to 10 mm. Battery cell according to claim 1, characterized in that the battery housing is a square housing, wherein the battery housing comprises first surfaces and a second surface, wherein the number of first surfaces is two, wherein the two first surfaces are opposite each other, wherein four second surfaces are opposite each other in pairs, wherein the area of ​​the first surface is larger than the area of ​​the second surface, and wherein the barrier main structure is arranged on a second surface between the two first surfaces. Battery cell according to claim 25, characterized in that the distance between the main barrier structure and the first surface is 3 to 20 mm, wherein the main barrier structure is arranged at least at a position of the weakened section close to the first surface. Battery cell according to claim 2, characterized in that the battery cell is a ternary lithium battery, wherein the ratio of h1 to h2 is in a range of 0.1 to 0.

65. Battery cell according to claim 27, characterized in that the ternary lithium battery has a nickel content in its positive electrode of greater than or equal to 0.7, wherein a ratio of h1 to h2 is in a range of 0.1 to 0.

58. Battery cell according to claim 2, characterized in that the battery cell is a lithium iron phosphate battery, wherein the ratio of h1 to h2 is in a range of 0.2 to 0.

75. Battery pack comprising several battery cells stacked on top of each other, characterized in that the battery cell is a battery cell according to one of claims 1 to 29, wherein a thermal insulation layer having a thickness of 1 to 5 mm is arranged between adjacent battery cells.

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