Secondary battery

Abstract

The utility model relates to the technical field of batteries, and discloses a secondary battery, which comprises a shell comprising a bottom wall and a side wall formed by extending around the peripheral edge of the bottom wall; one side of the pole group module along the third direction is provided with a pole lug; the cover plate body, the bottom wall and the side walls jointly define a containing cavity, the containing cavity is suitable for containing a pole group module, and a first hole penetrating through the cover plate body is formed in the cover plate body; the two pole assemblies are opposite in polarity, and each pole assembly comprises a pole bottom plate and two connecting columns formed by extending the pole bottom plate in the third direction; the connecting column penetrates through the first hole and is fixedly connected with the fixing block. A second hole penetrating through the bottom wall is formed in the bottom wall; and the anti-explosion valve is arranged on the bottom wall and covers the second hole. According to the secondary battery provided by the utility model, the safety of the battery can be improved while the quick charging capacity of the battery is improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to a battery technical field, concretely relates to a secondary battery. BACKGROUND

[0002] As one of the mainstream lithium battery packaging forms, square batteries have rapidly risen in the market due to their high energy density, high packaging reliability, high system efficiency, high stability and other advantages. However, with the continuous progress of technology and the continuous change of the market, square batteries still need to continuously improve their performance to meet higher demands. Fast charging technology can significantly shorten the charging time of the battery and improve the use convenience of the equipment. However, the fast charging capability of the square battery still needs to be improved to meet the user's demand for fast charging, and the safety of the battery is one of the most concerned issues. SUMMARY

[0003] Therefore, the utility model provides a secondary battery to solve the problem of how to improve the fast charging capability of the battery while improving the safety of the battery.

[0004] The utility model provides a secondary battery, which comprises:

[0005] A shell comprising a bottom wall and a side wall extending around the peripheral edge of the bottom wall;

[0006] A pole group module provided with a tab on one side in the third direction;

[0007] A cover plate body, which, together with the bottom wall and the side wall, forms a containing cavity, and the containing cavity is adapted to contain the pole group module, and the cover plate body is provided with a first hole penetrating through the cover plate body;

[0008] Two pole column assemblies with opposite polarities, each comprising a pole column bottom plate and two connecting columns extending from the pole column bottom plate in the third direction; the connecting columns pass through the first hole and are fixedly connected with the fixing block;

[0009] A second hole penetrating through the bottom wall is provided on the bottom wall;

[0010] An explosion-proof valve provided on the bottom wall and covering the second hole.

[0011] Beneficial effects: the secondary battery provided by the utility model, each pole post assembly adopts two connecting columns, and the pole lug is directly welded on the side of the pole post bottom plate away from the connecting column, not only saves the connecting sheet between the pole lug and the pole post, improves the space utilization rate of the battery interior, thereby improving the energy density of the battery, but also reduces the local current density and the internal resistance of the battery interior, improves the charging rate of the battery, and enhances the large current charging performance of the battery; at the same time, the explosion-proof valve is arranged on the bottom wall of the shell, on one hand, more setting space can be released on the cover plate body for the pole post assembly and the plurality of connecting columns, the welding area of the pole post bottom plate and the pole lug is ensured, thereby enhancing the overcurrent capacity of the pole post assembly, improving the charging rate of the battery, on the other hand, the space layout of the battery interior can be optimized, thereby improving the space utilization rate of the battery interior, and on the other hand, the thermal-electric separation can be realized, and the safety performance of the battery is improved.

[0012] In an alternative embodiment, the size of the cover plate body along the second direction is P1 mm, the sum of the sizes of the pole post bottom plates of the two pole post assemblies along the second direction is P2 mm, and P1 and P2 satisfy P2 / P1≥0.35.

[0013] Beneficial effects: P1 and P2 satisfy P2 / P1≥0.35, which not only ensures the full use of the cover plate body and the space along the second direction Y of the battery interior, but also ensures the welding area of the pole post bottom plate and the pole lug, reduces the internal resistance of the battery, enhances the overcurrent capacity of the pole post assembly, improves the charging rate of the battery, and reduces the fast charging temperature rise of the battery, thereby improving the safety of the battery while improving the fast charging capacity of the battery.

[0014] In an alternative embodiment, the side of the bottom wall away from the accommodating cavity has a sixth end face; along the third direction, the second hole includes a first counter-sink and a third hole in communication, the first counter-sink is arranged on the side close to the sixth end face, and the explosion-proof valve is arranged in the first counter-sink.

[0015] Beneficial effects: by arranging the explosion-proof valve in the first counter-sink, not only more setting space can be released on the cover plate body for the pole post assembly and the plurality of connecting columns, but also the thermal-electric separation can be realized, and the explosion-proof valve can be provided with sufficient installation space without increasing the size of the battery along the third direction Z, so that the structure of the entire battery is more compact, thereby optimizing the space occupation of the entire battery.

[0016] In an alternative embodiment, the bottom wall is further provided with a patch, the patch is attached to the sixth end face, and the projection of the patch on the bottom wall covers the explosion-proof valve.

[0017] Beneficial effects: By setting the patch on the bottom wall to cover the explosion-proof valve, not only can the external foreign matter pollution or corrosion to the explosion-proof valve be blocked, the normal working performance of the explosion-proof valve can be avoided, and the risk of abnormal opening of the explosion-proof valve can be reduced, thereby improving the safety of the battery.

[0018] In an optional embodiment, the side of the pole post bottom plate away from the connecting column is welded with the tab; the second insulating piece is arranged between the pole post bottom plate and the cover plate body;

[0019] The cover plate body is provided with a second end face on the side thereof facing the pole group module in the third direction; the pole post bottom plate is provided with a third end face on the side thereof away from the cover plate body in the third direction; the second insulating piece has a fourth end face abutting against the second end face and a fifth end face abutting against the pole group module;

[0020] The distance between the third end face and the second end face in the third direction is H1 mm, and H1 satisfies 1 / 3xH2≤H1+2xH3≤H2, wherein H2 is the distance between the fourth end face and the fifth end face in the third direction, and H3 is the thickness of the tab, and the units of H2 and H3 are both mm;

[0021] H1 is in the range of 0≤H1≤2.5;

[0022] H2 is in the range of 2≤H2≤8;

[0023] H3 is in the range of 0.1≤H3≤2.4.

[0024] Beneficial effects: H1, H2 and H3 satisfy 1 / 3xH2≤H1+2xH3≤H2, and on this basis, the value ranges of H1, H2 and H3 are further jointly limited, which not only ensures the overcurrent of the pole post assembly and the tab and improves the charging rate of the battery, but also optimizes the space occupation of the pole post assembly, the second insulating piece and the tab and the like in the battery, improves the space utilization rate in the battery, thereby improving the energy density of the battery, and in addition, the tab is prevented from being inserted into the interior of the pole group module and from being damaged by compression stress.

[0025] In an optional embodiment, the dimension of the pole post bottom plate in the third direction is H4, when the pole post bottom plate is an aluminum matrix bottom plate, H4 satisfies 1mm≤H4≤3mm; and when the pole post bottom plate is a copper matrix bottom plate, H4 satisfies 1mm≤H4≤2.5mm.

[0026] Beneficial effects: when the pole column bottom plate is an aluminum matrix bottom plate, H4 satisfies 1mm≤H4≤3mm, and when the pole column bottom plate is a copper matrix bottom plate, H4 satisfies 1mm≤H4≤2.5mm, on the one hand, the pole column bottom plate is prevented from being welded through, the reliability of the welding between the pole column bottom plate and the pole tab is ensured, on the other hand, the welding between the pole column bottom plate and the pole tab does not affect the sealing ring, the sealing failure of the sealing ring is prevented, and on the other hand, the space occupation of the pole column bottom plate in the battery is optimized, the space utilization in the battery is improved, and the weight and cost of the battery are reduced.

[0027] In an optional embodiment, the cover plate body is further provided with a liquid injection hole, and the liquid injection hole is located between the two pole column assemblies.

[0028] The second insulating part has a first end face facing the pole tab, and the first end face is spaced apart from the pole tab along the second direction; the minimum distance between the first end face and the pole tab along the second direction is P3 mm, the minimum distance between the side of the pole tab away from the first end face and the liquid injection hole along the second direction is P4 mm, and min{P3, P4} is P5;

[0029] The pole group module includes a positive pole piece, a negative pole piece and a separator, the separator includes a base material and a glue layer provided on at least one side surface of the base material, the coverage rate of the glue layer is K, and the secondary battery satisfies:

[0030] 90%≤K≤100%, 0

[0031] or, 20%≤K≤80%, 0

[0032] Beneficial effects: the secondary battery satisfies min{P3, P4} is P5, 90%≤K≤100%, 0

[0033] In an optional embodiment, for the same pole column assembly, the two connecting columns are eccentrically arranged on the pole column bottom plate along the second direction towards the first end face.

[0034] Beneficial effects: the two connecting columns of each pole column assembly are eccentrically arranged on the pole column bottom plate along the second direction Y towards the first end face of the second insulating part, which not only increases the design width of the middle part of the battery pack, but also increases the dislocation space of the pole tab in the battery along the second direction Y, and improves the process yield.

[0035] In an alternative embodiment, the pole group module comprises two pole group units arranged in pairs along the first direction; each pole group unit is provided with two tabs of opposite polarity; each pole column bottom plate is welded with the tabs of the same polarity of the two pole group units;

[0036] The pole column bottom plate and the two tabs of the same polarity form two welds extending along the second direction, and the distance between the two welds along the first direction is L2 mm; the size of the pole column bottom plate along the first direction is L3 mm, and L2 and L3 satisfy 0.05≤L2 / L3≤0.95;

[0037] And / or, the size of the weld along the second direction is W3, the size of the pole column bottom plate along the second direction is W4, and W3 and W4 satisfy 0.2≤W3 / W4≤0.95.

[0038] Beneficial effects: through L2 and L3 satisfying 0.05≤L2 / L3≤0.95, and / or, W3 and W4 satisfying 0.2≤W3 / W4≤0.95, on the one hand, the welding effect and welding reliability between the pole column bottom plate and the tabs are ensured, on the other hand, the overcurrent capacity of the connecting column is ensured, and on the other hand, the welding time between the pole column bottom plate and the tabs is avoided to be too long, and the welding yield between the pole column bottom plate and the tabs is ensured.

[0039] In an alternative embodiment, for the same pole column assembly, the sum of the cross-sectional areas of the two connecting columns is S1, and the total area of the welds formed by the pole column bottom plate and the two tabs is S2, and S1 and S2 satisfy 0.8≤S1 / S2≤2.0.

[0040] Beneficial effects: S1 and S2 satisfy S1 / S2≥0.8, thereby ensuring the consistency of overcurrent; at the same time, S1 and S2 satisfy S1 / S2≤2.0, thereby ensuring the material utilization rate, and reducing the volume and material of the pole column bottom plate as much as possible under the condition of ensuring the overcurrent capacity of the pole column assembly, and improving the mass energy density of the battery.

[0041] In an alternative embodiment, the fixing block has a second sunken platform, the second sunken platform is recessed along the third direction from the side of the fixing block away from the cover plate body, and the second sunken platform is circumferentially arranged around the connecting column;

[0042] The end of the connecting column away from the pole column bottom plate along the third direction is provided with a protruding part, the protruding part is extended radially from the outer circumferential surface of the connecting column to the direction away from the connecting column; the protruding part abuts against the second sunken platform along the third direction; wherein the volume of the protruding part is V1 mm 3 ;

[0043] The end of the connecting column away from the pole column bottom plate along the third direction is provided with a positioning blind hole, and the space volume of the positioning blind hole is V2 mm 3V1 and V2 satisfy 1.05≤V2 / V1≤1.5;

[0044] And / or, the angle of the inclined surface of the positioning blind hole is β, and β satisfies 90°≤β≤180°.

[0045] Beneficial effect: V1 and V2 satisfy 1.05≤V2 / V1≤1.5, and β satisfies 90°≤β≤180°, thereby ensuring the riveting effect of the connecting column and the fixing block, reducing the gap between the protruding part after riveting and the fixing block, and facilitating the subsequent welding of the connecting column and the fixing block.

[0046] In an optional embodiment, the protruding part is welded to the fixing block away from one side of the second sink in the third direction.

[0047] Beneficial effect: By welding the protruding part to the fixing block away from one side of the second sink in the third direction Z, the contact resistance between the connecting column and the fixing block can be reduced, the overcurrent capacity can be improved, and foreign matter can be prevented from entering the gap and the contact surface from being oxidized.

[0048] In an optional embodiment, the distance between the two connecting columns of the same polarity in the second direction is W1, and W1 satisfies 2mm≤W1≤30mm;

[0049] And / or, the distance between the connecting column and the edge of the fixing block is W2, and W2 satisfies 2mm≤W2≤30mm;

[0050] And / or, the size of the fixing block in the first direction is L1 mm, and the diameter of the connecting column is D mm, and L1 and D satisfy 1.1≤L1 / D≤5;

[0051] And / or, the size of the cover plate body in the first direction is L2 mm, and L2 satisfies 1.1≤L2 / L1≤5.

[0052] Beneficial effect: The distance W1 between the two connecting columns of the same polarity in the second direction Y is satisfied by W1≥2mm, and the distance W2 between the connecting column and the edge of the fixing block is satisfied by W2≥2mm, thereby preventing the two connecting columns from being riveted and extruded, avoiding the deformation of the fixing block or the cover plate body due to riveting, and leaving appropriate space for the welding of the connecting column and the tab; in addition, W1≤30mm and W2≤30mm, thereby avoiding design redundancy and improving the quality energy density of the battery.

[0053] L1 and D satisfy L1 / D≥1.1, and L1 and L2 satisfy L2 / L1≥1.1, on the one hand, the heat influence of welding heat on the first insulation piece during the welding process of the connecting column and the fixing block and the welding process of the cover plate body and the shell periphery is prevented, on the other hand, laser interference is prevented, and on the other hand, riveting cracking and deformation can be avoided; meanwhile, L1 / D≤5 and L2 / L1≤5, so as to avoid design redundancy waste and improve the mass energy density of the battery. BRIEF DESCRIPTION OF DRAWINGS

[0054] In order to more clearly illustrate the specific embodiment of the utility model or the technical scheme in the prior art, the drawings needed to be used in the specific embodiment or the prior art description will be briefly introduced below, and obviously, the drawings in the following description are some embodiments of the utility model, and those skilled in the art can also obtain other drawings according to these drawings without creating creative labor.

[0055] Figure 1 It is a top view of a secondary battery of the embodiment of the utility model;

[0056] Figure 2 It is a sectional view of A-A in the figure; Figure 1

[0057] Figure 3 It is a local enlarged schematic view of B in the figure; Figure 2

[0058] Figure 4 It is a local enlarged schematic view of C in the figure; Figure 2

[0059] Figure 5 It is a sectional view of the utility model embodiment after hiding the explosion-proof valve; Figure 4

[0060] Figure 6 It is a local enlarged schematic view of E in the figure; Figure 3

[0061] Figure 7 It is a sectional view of the cover plate body; Figure 2

[0062] Figure 8 It is a sectional view of the second insulation piece; Figure 2

[0063] Figure 9 It is a perspective view of a secondary battery of the embodiment of the utility model after hiding the shell;

[0064] Figure 10 Figure 9 It is a perspective view of the pole assembly;

[0065] ​​​​​​​​Figure 11 Fig. 1 is a perspective view of a polar plate assembly according to an embodiment of the present application; Figure 2 Fig. 2 is a sectional view of a polar post assembly of the polar plate assembly;

[0066] Figure 12 Fig. 3 is a perspective view of a polar group module of the polar plate assembly; Figure 9 Fig. 4 is a top view of the polar group module;

[0067] Figure 13 Fig. 5 is a sectional view of the polar group module; Figure 1 Fig. 6 is a top view of the polar group module;

[0068] Figure 14 Fig. 7 is a perspective view of the polar post assembly and the polar group module; Figure 9 Fig. 8 is a top view of the polar post assembly and the polar group module.

[0069] Figure 15 Fig. 9 is a sectional view of the polar post assembly and the polar group module. Figure 1 BRIEF DESCRIPTION OF THE DRAWINGS

[0070] 10, polar group module; 11, polar group unit; 111, polar lug;

[0071] 20, cover plate body; 21, first hole; 22, second end surface; 23, liquid injection hole;

[0072] 30, fixing block; 31, second sink;

[0073] 40, first insulating member;

[0074] 50, polar post assembly; 51, polar post bottom plate; 511, third end surface; 512, welding mark; 52, connecting post; 521, protruding portion; 522, positioning blind hole;

[0075] 60, second insulating member; 61, first end surface; 62, fourth end surface; 63, fifth end surface;

[0076] 70, sealing ring;

[0077] 80, housing; 81, bottom wall; 811, second hole; 812, sixth end surface; 813, first sink; 814, third hole; 82, side wall; 83, accommodating cavity;

[0078] 90, explosion-proof valve;

[0079] 100, patch;

[0080] X—first direction; Y—second direction; Z—third direction.

[0081] DETAILED DESCRIPTION

[0082] ​In order to make the purpose, technical scheme and advantages of the embodiments of the utility model clearer, the technical scheme in the embodiments of the utility model will be clearly and completely described in combination with the drawings in the embodiments of the utility model below. Obviously, the described embodiments are part of the embodiments of the utility model, rather than all the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by the person skilled in the art without creative labor belong to the protection scope of the utility model.

[0083] The embodiments of the utility model will be described below in combination with Figures 1 to 15 .

[0084] According to the embodiments of the utility model, a secondary battery is provided, which comprises:

[0085] The shell 80, please see Figure 2 , comprises a bottom wall 81 and a side wall 82 extending around the side edge of the bottom wall 81;

[0086] The pole group module 10, please see Figure 3 , is provided with a tab 111 on one side along the third direction Z;

[0087] The cover plate body 20, still see Figure 2 , together with the bottom wall 81 and the side wall 82 forms a containing cavity 83, and the containing cavity 83 is suitable for containing the pole group module 10, please see Figure 7 , the cover plate body 20 is provided with a first hole 21 penetrating the cover plate body 20;

[0088] Two pole column assemblies 50 with opposite polarities, each pole column assembly 50 comprises a pole column bottom plate 51 and two connecting columns 52 extending from the pole column bottom plate 51 along the third direction Z; the connecting column 52 penetrates the first hole 21 and is fixedly connected with the fixed block 30;

[0089] Please see Figure 5 , the bottom wall 81 is provided with a second hole 811 penetrating the bottom wall 81;

[0090] The explosion-proof valve 90 is arranged on the bottom wall 81 and covers the second hole 811.

[0091] It should be noted that "the first direction X" in the text refers to the thickness direction of the secondary battery and / or the width direction of the cover plate body 20; "the second direction Y" in the text refers to the width direction of the secondary battery and / or the length direction of the cover plate body 20; "the third direction Z" in the text refers to the height direction of the secondary battery and / or the thickness direction of the cover plate body 20.

[0092] The secondary battery provided by the utility model, each pole post assembly 50 adopts two connecting columns 52, and the pole lug 111 is directly welded on the side of the pole post bottom plate 51 away from the connecting column 52, not only saves the connecting sheet between the pole lug 111 and the pole post, improves the space utilization rate of the battery interior, thereby improving the energy density of the battery, but also reduces the local current density and the internal resistance of the battery interior, improves the charging rate of the battery, and enhances the large current charging performance of the battery; meanwhile, the explosion-proof valve 90 is arranged on the bottom wall 81 of the shell 80, on the one hand, more setting space is released on the cover plate body 20 for the pole post assembly 50 and the plurality of connecting columns 52, the welding area of the pole post bottom plate 51 and the pole lug 111 is ensured, thereby enhancing the overcurrent capacity of the pole post assembly 50, improving the charging rate of the battery, on the other hand, the space layout of the battery interior is optimized, thereby improving the space utilization rate of the battery interior, and on the other hand, the thermal-electric separation is realized, and the safety performance of the battery is improved.

[0093] In some embodiments, referring to Figure 7 As shown in the figure, the size of the cover plate body 20 along the second direction Y is P1 mm, the sum of the sizes of the pole post bottom plates 51 of the two pole post assemblies 50 along the second direction Y is P2 mm, and P1 and P2 satisfy P2 / P1≥0.35.

[0094] Wherein, the two pole post assemblies 50 are completely same in structure, and P2 / P1<1.

[0095] By arranging the explosion-proof valve 90 on the bottom wall 81 of the shell 80, more setting space is released on the cover plate body 20 for the pole post assembly 50 and the plurality of connecting columns 52, and the thermal-electric separation is realized, P1 and P2 satisfy P2 / P1≥0.35, not only can guarantee the full use of the cover plate body 20 and the space along the second direction Y in the battery interior, but also can ensure the welding area of the pole post bottom plate 51 and the pole lug 111, reduce the internal resistance of the battery, enhance the overcurrent capacity of the pole post assembly 50, improve the charging rate of the battery, and reduce the fast charging temperature rise of the battery, thereby improving the safety performance of the battery while improving the fast charging capacity of the battery.

[0096] In some embodiments, referring to Figure 5 As shown in the figure, the side of the bottom wall 81 away from the containing cavity 83 has a sixth end face 812; along the third direction Z, the second hole 811 includes a first sunken platform 813 and a third hole 814 in communication, the first sunken platform 813 is arranged on the side close to the sixth end face 812, please combine Figure 4 As shown in the figure, the explosion-proof valve 90 is arranged in the first sunken platform 813.

[0097] By arranging the explosion-proof valve 90 in the first sink 813, not only can more space be released on the cover plate body 20 for the pole group assembly 50 and the plurality of connecting columns 52, but also the thermal and electrical separation can be achieved, and sufficient installation space can be provided for the explosion-proof valve 90 without increasing the size of the battery along the third direction Z, so that the structure of the entire battery is more compact, thereby optimizing the space occupation of the entire battery.

[0098] In some embodiments, as shown in Figure 4 The bottom wall 81 is also provided with a patch 100, the patch 100 is attached to the sixth end face 812, and the projection of the patch 100 on the bottom wall 81 covers the explosion-proof valve 90.

[0099] By arranging the patch 100 on the bottom wall 81 to cover the explosion-proof valve 90, not only can the external foreign matter pollution or corrosion to the explosion-proof valve 90 be blocked to avoid affecting the normal working performance of the explosion-proof valve 90, but also the explosion-proof valve 90 can be prevented from being accidentally touched or damaged during use, thereby reducing the risk of abnormal opening of the explosion-proof valve 90, and improving the safety of the battery.

[0100] In some embodiments, the side of the pole bottom plate 51 away from the connecting column 52 is welded with the tab 111; as shown in Figure 3 The second insulating piece 60 is arranged between the pole bottom plate 51 and the cover plate body 20;

[0101] As shown in Figure 7 The cover plate body 20 is provided with a second end face 22 on the side facing the pole group module 10 along the third direction Z; as shown in Figure 11 The pole bottom plate 51 is provided with a third end face 511 on the side away from the cover plate body 20 along the third direction Z; as shown in Figure 8 The second insulating piece 60 has a fourth end face 62 abutting against the second end face 22 and a fifth end face 63 abutting against the pole group module 10;

[0102] Still referring to Figure 3 The distance between the third end face 511 and the second end face 22 along the third direction Z is H1 mm, and H1 satisfies 1 / 3×H2≤H1+2×H3≤H2, wherein H2 is the distance between the fourth end face 62 and the fifth end face 63 along the third direction Z, and H3 is the thickness of the tab 111, and the units of H2 and H3 are mm;

[0103] The value range of H1 is 0≤H1≤2.5;

[0104] And / or, the value range of H2 is 2≤H2≤8;

[0105] And / or, the value range of H3 is 0.1≤H3≤2.4.

[0106] It should be noted that if the value of H1+2xH3 is too small, not only the overcurrent of the tab 111 cannot be guaranteed, the charging rate of the battery is affected, but also the space utilization inside the battery is easily reduced, therefore, H1+2xH3≥1 / 3xH2 should be met; if the value of H1+2xH3 is too large, not only the tab 111 is easily inserted into the inside of the pole group module 10, but also the tab 111 is easily damaged by compression stress, therefore, H1+2xH3≤H2 should also be met.

[0107] H1, H2 and H3 meet 1 / 3xH2≤H1+2xH3≤H2, and on this basis, the value range of H1, H2 and H3 is further combined to limit, not only the overcurrent of the pole assembly 50 and the tab 111 can be guaranteed, the charging rate of the battery is improved, but also the space occupation of the pole assembly 50, the second insulation piece 60 and the tab 111 and other components inside the battery is optimized, the space utilization inside the battery is improved, thereby the energy density of the battery is improved, in addition, the tab 111 is avoided to be inserted into the inside of the pole group module 10, and the tab 111 is prevented from being damaged by compression stress.

[0108] Further, the first insulation piece 40 is arranged between the fixed block 30 and the cover plate body 20; the sealing ring 70 is arranged between the pole assembly 50 and the cover plate body 20.

[0109] In some embodiments, as shown in Figure 11 The size of the pole bottom plate 51 along the third direction Z is H4, when the pole bottom plate 51 is an aluminum matrix bottom plate, H4 meets 1mm≤H4≤3mm; when the pole bottom plate 51 is a copper matrix bottom plate, H4 meets 1mm≤H4≤2.5mm.

[0110] It should be noted that if the size H4 of the pole bottom plate 51 along the third direction Z is too small, not only the pole bottom plate 51 is easily welded through during the welding process of the pole bottom plate 51 and the tab 111, the reliability of the welding of the pole bottom plate 51 and the tab 111 is affected, but also the welding heat of the pole bottom plate 51 and the tab 111 easily affects the sealing ring 70, causing the sealing failure of the sealing ring 70, therefore, H4 meets H4≥1mm; if the size H4 of the pole bottom plate 51 along the third direction Z is too large, not only the space occupation of the pole bottom plate 51 inside the battery is easily increased, the space utilization inside the battery is reduced, but also the battery weight reduction and cost reduction are not conducive, therefore, when the pole bottom plate 51 is an aluminum matrix bottom plate, H4≤3mm; when the pole bottom plate 51 is a copper matrix bottom plate, H4≤2.5mm.

[0111] When the pole column bottom plate 51 is an aluminum matrix bottom plate, H4 satisfies 1mm≤H4≤3mm, and when the pole column bottom plate 51 is a copper matrix bottom plate, H4 satisfies 1mm≤H4≤2.5mm, which on one hand avoids welding through the pole column bottom plate 51, ensures the reliability of the welding of the pole column bottom plate 51 and the pole tab 111, on the other hand avoids the welding heat of the pole column bottom plate 51 and the pole tab 111 affecting the sealing ring 70, prevents the sealing failure of the sealing ring 70, and on the other hand can optimize the space occupation of the pole column bottom plate 51 in the battery, improve the space utilization rate in the battery, and is beneficial to the weight reduction and cost reduction of the battery.

[0112] Preferably, H4 satisfies 1.5mm≤H4≤2.0mm, wherein the size of the aluminum matrix bottom plate along the third direction Z is greater than or equal to the size of the copper matrix bottom plate along the third direction Z.

[0113] In some embodiments, referring to Figure 2 As shown in the figure, the cover plate body 20 is also provided with a liquid injection hole 23, and the liquid injection hole 23 is located between the two pole column assemblies 50.

[0114] Referring to Figure 8 As shown in the figure, the second insulating part 60 has a first end face 61 facing the pole tab 111, and the first end face 61 is arranged opposite to the pole tab 111 along the second direction Y; the minimum distance between the first end face 61 and the pole tab 111 along the second direction Y is P3mm, and the minimum distance between the side of the pole tab 111 away from the first end face 61 and the liquid injection hole 23 along the second direction Y is P4mm, and min{P3, P4} is P5.

[0115] The pole group module 10 includes a positive pole piece, a negative pole piece and a separator, the separator includes a base material and a glue layer arranged on at least one side surface of the base material, the coverage rate of the glue layer is K, and the secondary battery satisfies:

[0116] 90%≤K≤100%, 0

[0117] Or, 20%≤K≤80%, 0

[0118] It should be noted that "min{P3, P4} is P5" means that the minimum one of the array P3 and P4 is P5. Since the pole tab 111 is multi-layered and stacked, the multi-layered pole tab 111 has a certain layer error after the formation of the battery cell, and therefore a certain accommodation space needs to be reserved for the pole tab 111 in the battery.

[0119] The secondary battery satisfies min{P3, P4} = P5, 90%≤K≤100%, 0

[0120] In some embodiments, as shown in Figure 2 、 Figure 3 and Figure 11 , for the same pole column assembly 50, the two connecting columns 52 are eccentrically arranged on the pole column bottom plate 51 along the second direction Y towards the first end face 61 close to the second insulating member 60.

[0121] On the cover plate body 20, for the two pole column assemblies 50 with opposite polarities, the two connecting columns 52 of each pole column assembly 50 are eccentrically arranged on the pole column bottom plate 51 along the second direction Y towards the first end face 61 close to the second insulating member 60, which not only increases the design width of the middle line of the battery pack, but also increases the dislocation space of the tab 111 along the second direction Y inside the battery, thereby improving the process yield.

[0122] In some embodiments, as shown in Figure 9 , the pole group module 10 includes two pole group units 11 arranged in pairs along the first direction X; as shown in Figure 12 , each pole group unit 11 is provided with two tabs 111 with opposite polarities; as shown in Figure 14 , each pole column bottom plate 51 is welded with the tabs 111 of the same polarity of the two pole group units 11;

[0123] as shown inFigure 13 As shown, the pole post bottom plate 51 and the two tab 111 of the same polarity form two welds 512 extending along the second direction Y by welding, and the distance between the two welds 512 along the first direction X is L2 mm; see Figure 15 As shown, the size of the pole post bottom plate 51 along the first direction X is L3 mm, and L2 and L3 satisfy 0.05≤L2 / L3≤0.95.

[0124] And / or, the size of the weld 512 along the second direction Y is W3, and the size of the pole post bottom plate 51 along the second direction Y is W4, and W3 and W4 satisfy 0.2≤W3 / W4≤0.95.

[0125] It should be noted that the value of "L2 / L3" and / or the value of "W3 / W4" cannot be too small, otherwise not only the welding effect and welding reliability between the pole post bottom plate 51 and the tab 111 cannot be guaranteed, but also the local current density between the pole post bottom plate 51 and the tab 111 is easily increased, reducing the overcurrent capacity of the connecting post 52, therefore, L2 / L3≥0.05, W3 / W4≥0.2 shall be met; if the value of "L2 / L3" and / or the value of "W3 / W4" is too large, it is easy to cause the welding positioning size between the pole post bottom plate 51 and the tab 111 to be insufficient and the welding size to be too large, and the welding time to be too long, ultimately affecting the welding yield between the pole post bottom plate 51 and the tab 111, therefore, L2 / L3≤0.95, W3 / W4≤0.95 shall also be met.

[0126] By meeting 0.05≤L2 / L3≤0.95 and / or 0.2≤W3 / W4≤0.95, on the one hand, the welding effect and welding reliability between the pole post bottom plate 51 and the tab 111 are guaranteed, on the other hand, the overcurrent capacity of the connecting post 52 is guaranteed, and on the other hand, the welding time between the pole post bottom plate 51 and the tab 111 is avoided to be too long, and the welding yield between the pole post bottom plate 51 and the tab 111 is ensured.

[0127] In some embodiments, for the same pole post assembly 50, the sum of the cross-sectional areas of the two connecting posts 52 is S1, and the total area of the welds 512 formed by the pole post bottom plate 51 and the two tabs 111 is S2, and S1 and S2 satisfy 0.8≤S1 / S2≤2.0.

[0128] S1 and S2 satisfy S1 / S2≥0.8, thereby ensuring the consistency of overcurrent; at the same time, S1 and S2 satisfy S1 / S2≤2.0, thereby ensuring the material utilization rate, and reducing the volume and material of the pole post bottom plate 51 as much as possible under the condition of ensuring the overcurrent capacity of the pole post assembly 50, and improving the quality energy density of the battery.

[0129] In some embodiments, see Figure 6As shown, the fixing block 30 has a second sunken platform 31 recessed from the side of the fixing block 30 away from the cover plate body 20 along the third direction Z, and the second sunken platform 31 is circumferentially arranged around the connecting column 52.

[0130] The connecting column 52 is provided with a protruding portion 521 at one end away from the polar column bottom plate 51 along the third direction Z, and the protruding portion 521 extends radially from the outer circumferential surface of the connecting column 52 in a direction away from the connecting column 52; the protruding portion 521 abuts against the second sunken platform 31 along the third direction Z; wherein the volume of the protruding portion 521 is V1 mm 3 ;

[0131] The connecting column 52 is provided with a positioning blind hole 522 at one end away from the polar column bottom plate 51 along the third direction Z, and the space volume of the positioning blind hole 522 is V2 mm 3 ; V1 and V2 satisfy 1.05≤V2 / V1≤1.5;

[0132] And / or, please refer to Figure 11 As shown, the angle of the inclined surface of the positioning blind hole 522 is β, and β satisfies 90°≤β≤180°.

[0133] It should be noted that, in the process, the connecting column 52 passes through the first hole 21 and is riveted with the fixing block 30, and in this process, the end face where the positioning blind hole 522 of the connecting column 52 is located can be pressed by a riveting tool, so that the material of the connecting column 52 flows and forms the protruding portion 521 and the positioning blind hole 522, and V1 and V2 satisfy 1.05≤V2 / V1≤1.5, and β satisfies 90°≤β≤180° at the same time, thereby ensuring the riveting effect of the connecting column 52 and the fixing block 30, reducing the gap between the protruding portion 521 and the fixing block 30 after riveting, and facilitating subsequent welding of the connecting column 52 and the fixing block 30.

[0134] In some embodiments, the side of the protruding portion 521 away from the second sunken platform 31 along the third direction Z is welded with the fixing block 30.

[0135] By welding the side of the protruding portion 521 away from the second sunken platform 31 along the third direction Z with the fixing block 30, the contact resistance between the connecting column 52 and the fixing block 30 can be reduced, the overcurrent capacity can be improved, and foreign matter can be prevented from entering the gap and the contact surface from being oxidized.

[0136] In some embodiments, please refer to Figure 1 As shown, the distance between two connecting columns 52 of the same polarity along the second direction Y is W1, and W1 satisfies 2mm≤W1≤30mm;

[0137] And / or, the distance between the connecting column 52 and the edge of the fixing block 30 is W2, and W2 satisfies 2mm≤W2≤30mm;

[0138] And / or, the size of the fixed block 30 along the first direction X is L1 mm, please see Figure 11 As shown, the diameter of the connecting column 52 is D mm, and L1 and D satisfy 1.1≤L1 / D≤5.

[0139] And / or, the size of the cover plate body 20 along the first direction X is L2 mm, and L2 satisfies 1.1≤L2 / L1≤5.

[0140] The distance W1 between two connecting columns 52 with the same polarity along the second direction Y is greater than or equal to 2 mm, and the distance W2 between the connecting column 52 and the edge of the fixed block 30 is greater than or equal to 2 mm, so as to prevent the riveting extrusion of the two connecting columns 52, avoid the riveting cracking deformation of the fixed block 30 or the cover plate body 20, and leave appropriate space for the welding of the connecting column 52 and the tab; in addition, W1≤30 mm and W2≤30 mm, so as to avoid design redundancy and improve the mass energy density of the battery.

[0141] L1 and D satisfy L1 / D≥1.1, and L1 and L2 satisfy L2 / L1≥1.1, which can prevent the thermal influence of the welding heat on the first insulating piece 40 during the welding of the connecting column 52 and the fixed block 30 and the welding of the cover plate body 20 and the shell 80, prevent laser interference, and avoid riveting cracking deformation; in addition, L1 / D≤5 and L2 / L1≤5, so as to avoid design redundancy and improve the mass energy density of the battery.

[0142] Preferably, W1 satisfies 5 mm≤W1≤15 mm.

[0143] In combination with Table 1 below, the fast charging capacity, charging and fast charging temperature rise of the secondary battery provided by the embodiment of the utility model are verified through a plurality of test examples.

[0144] Table 1

[0145]

[0146] Therefore, the battery core assembly provided by the utility model can enhance the overcurrent capacity of the pole assembly, improve the charging rate of the battery, and reduce the fast charging temperature rise of the battery, so as to improve the safety of the battery while improving the fast charging capacity of the battery.

[0147] Although the embodiments of the utility model are described in combination with the drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the utility model, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A secondary battery characterized by comprising: The shell (80) comprises a bottom wall (81) and a side wall (82) extending around the side edge of the bottom wall (81); the pole group module (10) is provided with a lug (111) on one side in the third direction (Z); the cover plate body (20) is jointly enclosed with the bottom wall (81) and the side wall (82) to form a containing cavity (83), and the containing cavity (83) is adapted to contain the pole group module (10); the cover plate body (20) is provided with a first hole (21) penetrating through the cover plate body (20); two pole column assemblies (50) with opposite polarities are provided, each of the pole column assemblies (50) comprises a pole column bottom plate (51) and two connecting columns (52) extending from the pole column bottom plate (51) in the third direction (Z); the connecting columns (52) penetrate through the first hole (21) and are fixedly connected with the fixing block (30); the bottom wall (81) is provided with a second hole (811) penetrating through the bottom wall (81); and an explosion-proof valve (90) is arranged on the bottom wall (81) and covers the second hole (811). The size of the cover plate body (20) in the second direction (Y) is P1 mm, the sum of the sizes of the pole column bottom plates (51) of the two pole column assemblies (50) in the second direction (Y) is P2 mm, and P1 and P2 satisfy P2 / P1≥0.

35. The side of the bottom wall (81) away from the containing cavity (83) has a sixth end face (812); in the third direction (Z), the second hole (811) comprises a first sunken platform (813) and a third hole (814) connected in communication, the first sunken platform (813) is arranged on the side close to the sixth end face (812), and the explosion-proof valve (90) is arranged in the first sunken platform (813). The bottom wall (81) is further provided with a patch (100), the patch (100) is attached to the sixth end face (812), and the projection of the patch (100) on the bottom wall (81) covers the explosion-proof valve (90). The side of the pole column bottom plate (51) away from the connecting column (52) is welded with the lug (111); the second insulating piece (60) is arranged between the pole column bottom plate (51) and the cover plate body (20); The side of the cover plate body (20) in the third direction (Z) towards the pole group module (10) is provided with a second end face (22); the side of the pole column bottom plate (51) in the third direction (Z) away from the cover plate body (20) is provided with a third end face (511); the second insulating piece (60) has a fourth end face (62) abutting against the second end face (22) and a fifth end face (63) abutting against the pole group module (10); ​ 2. The secondary battery according to claim 1, characterized by ​ 3. The secondary battery according to claim 1, characterized by ​ 4. The secondary battery according to claim 3, characterized by ​ 5. The secondary battery according to claim 1, characterized by ​ ​ A distance between the third end surface (511) and the second end surface (22) along the third direction (Z) is H1 mm, H1 satisfies 1 / 3×H2≤H1+2×H3≤H2, wherein H2 is a distance between the fourth end surface (62) and the fifth end surface (63) along the third direction (Z), and H3 is a thickness of the tab (111), and units of H2 and H3 are both mm; H1 is in a range of 0≤H1≤2.5; And / or, H2 is in a range of 2≤H2≤8; And / or, H3 is in a range of 0.1≤H3≤2.

4.

6. The secondary battery according to claim 5, characterized by A dimension of the pole column bottom plate (51) along the third direction (Z) is H4, when the pole column bottom plate (51) is an aluminum matrix bottom plate, H4 satisfies 1mm≤H4≤3mm; when the pole column bottom plate (51) is a copper matrix bottom plate, H4 satisfies 1mm≤H4≤2.5mm.

7. The secondary battery according to claim 5, characterized by The cover plate body (20) is further provided with a liquid injection hole (23), and the liquid injection hole (23) is located between the two pole column assemblies (50); The second insulating part (60) has a first end surface (61) facing the tab (111), and the first end surface (61) is oppositely spaced apart from the tab (111) along a second direction (Y); a minimum distance between the first end surface (61) and the tab (111) along the second direction (Y) is P3 mm, and a minimum distance between a side of the tab (111) facing away from the first end surface (61) and the liquid injection hole (23) along the second direction (Y) is P4 mm, and min{P3, P4} is P5; The pole group module (10) comprises a positive plate, a negative plate and a separator, the separator comprises a base material and a glue layer provided on at least one side surface of the base material, the coverage of the glue layer is K, and the secondary battery satisfies: 90%≤K≤100%, 0 Or, 20%≤K≤80%, 0 8. The secondary battery according to claim 7, characterized by For the same pole column assembly (50), the two connecting columns (52) are eccentrically arranged on the pole column bottom plate (51) along the second direction (Y) towards the first end surface (61).

9. The secondary battery according to claim 1, characterized by The pole group module (10) comprises two pole group units (11) arranged in pairs along a first direction (X); each of the pole group units (11) is provided with two tabs (111) with opposite polarities; and each of the pole column bottom plates (51) is welded with the tabs (111) with the same polarity of the two pole group units (11); The pole column bottom plate (51) and the two tabs (111) with the same polarity are welded to form two welding marks (512) extending along the second direction (Y), and a distance between the two welding marks (512) along the first direction (X) is L2 mm; a dimension of the pole column bottom plate (51) along the first direction (X) is L3 mm, and L2 and L3 satisfy 0.05≤L2 / L3≤0.

95. And / or, a size of the welding mark (512) along the second direction (Y) is W3, a size of the pole post bottom plate (51) along the second direction (Y) is W4, W3 and W4 satisfy 0.2≤W3 / W4≤0.

95.

10. The secondary battery according to claim 9, characterized by For the same pole post assembly (50), a sum of cross-sectional areas of two connection posts (52) is S1, a total area of the welding mark (512) formed by the pole post bottom plate (51) and two tabs (111) is S2, S1 and S2 satisfy 0.8≤S1 / S2≤2.

0.

11. The secondary battery according to any one of claims 1 to 10, characterized by The fixing block (30) has a second sunken platform (31) recessed from a side of the fixing block (30) away from the cover plate body (20) along the third direction (Z), and the second sunken platform (31) is circumferentially arranged around the connection post (52). The connecting column (52) is provided with a protruding portion (521) at one end away from the pole column bottom plate (51) along the third direction (Z), the protruding portion (521) is extended from the outer peripheral surface of the connecting column (52) in the radial direction away from the connecting column (52); the protruding portion (521) abuts along the third direction (Z) with the second sink (31); wherein the volume of the protruding portion (521) is V1 mm 3 ; The connecting column (52) is provided with a positioning blind hole (522) at one end away from the pole column bottom plate (51) along the third direction (Z), and the space volume of the positioning blind hole (522) is V2 mm 3 ; V1 and V2 satisfy 1.05≤V2 / V1≤1.

5. And / or, an angle of an inclined surface of the positioning blind hole (522) is β, and β satisfies 90°≤β≤180°.

12. The secondary battery according to claim 11, characterized by The protruding part (521) is welded to the fixing block (30) from a side of the second sunken platform (31) away from the fixing block (30).

13. The secondary battery according to claim 11, characterized by A distance between two connection posts (52) with the same polarity along the second direction (Y) is W1, and W1 satisfies 2mm≤W1≤30mm. And / or, a distance between the connection post (52) and an edge of the fixing block (30) is W2, and W2 satisfies 2mm≤W2≤30mm. And / or, a size of the fixing block (30) along the first direction (X) is L1 mm, a diameter of the connection post (52) is D mm, and L1 and D satisfy 1.1≤L1 / D≤5. And / or, a size of the cover plate body (20) along the first direction (X) is L2 mm, and L2 satisfies 1.1≤L2 / L1≤5.

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