An electric cell

Abstract

The application relates to the technical field of power batteries, and particularly discloses a battery cell, which comprises a pole group and a cover plate assembly, the pole group is arranged on one side of the cover plate assembly, four corner portions of a negative plate of the pole group are each provided with a first avoiding corner, two corner portions of a positive plate on the side close to a positive output end are each provided with a second avoiding corner, two corner portions of the positive plate on the side close to a negative output end are each provided with a third avoiding corner, and the edges of the projections of the second avoiding corner and the third avoiding corner in a first plane are located on the inner side of the edges of the projection of the first avoiding corner in the first plane. The first avoiding corner, the second avoiding corner and the third avoiding corner are arranged, so that the acting force between the first plastic part of the cover plate assembly and the corner portions of the pole group is small, the positive plate and the negative plate are prevented from being pressed and damaged, and the safety performance of the battery cell is good.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power batteries, in particular to a battery cell. BACKGROUND

[0002] The structure of the battery cell generally comprises a cover plate assembly (integrating a pole, a lower plastic part, an explosion-proof valve, a liquid injection hole, etc.), a shell, a bare cell insulating film, a pole group, electrolyte, etc. The cover plate and the shell are welded to form a sealed space with a certain mechanical strength to protect the pole group. The pole group is electrically connected by welding the pole tab to the pole. The bare cell insulating film wraps the pole group and is fixed to the lower plastic part in the cover plate assembly on both sides by heat melting, thereby ensuring the insulation of the pole group from the shell. The cover plate assembly is mainly assembled by the pole, an aluminum sheet, the lower plastic part, the explosion-proof valve, etc., wherein the pole is used to lead out the current inside the battery cell. The main function of the explosion-proof valve is to release the high-temperature and high-pressure gas inside the battery cell in a directional manner when the battery cell is in thermal runaway due to mechanical impact, internal abnormal lap joint short circuit, etc., thereby ensuring the safety performance of the battery cell. The periphery of the aluminum sheet is welded to the shell to realize the assembly of the shell cover. The lower plastic part provides an insulating space to protect the pole tab and is used to press and fix the pole group to avoid the pole group from moving inside the shell.

[0003] In order to ensure that the lower plastic part has a good fixing effect on the pole group, it is generally required to ensure that the compression amount of the lower plastic part to the length direction of the pole group is about 3-5 mm. However, the boss of the lower plastic part used to press the pole group is usually a flat structure, which is completely attached to the end surface of the length direction of the pole group. When the cover plate assembly enters the shell or the finished battery cell is in a vibrating, impacting, etc. environment, the pole group moves inside the shell, the interaction force between the boss of the lower plastic part and the pole group increases, and the pole piece is often pressed at the corner of the pole group. The problem of the pole piece being pressed is often pressed, and the safety performance of the battery cell is reduced. SUMMARY

[0004] The purpose of the present application is to provide a battery cell which improves the structure of the corner position of the pole group, thereby reducing the interaction force between the first plastic part and the pole group, avoiding the positive pole piece and the negative pole piece of the pole group from being pressed, and having good safety performance of the battery cell.

[0005] To achieve the above purpose, the present application adopts the following technical solutions:

[0006] The present application provides a battery cell, comprising:

[0007] a pole group, the pole group comprising a negative pole piece, a positive pole piece and a separator, the positive pole piece and the negative pole piece being arranged in a stack along a first direction, and the separator being arranged between the positive pole piece and the negative pole piece; the pole group having a positive output end and a negative output end at both ends along a second direction;

[0008] The first avoiding corner is arranged on two corners of the negative plate close to one side of the positive output end, and the first avoiding corner is arranged on two corners of the negative plate close to one side of the negative output end; the second avoiding corner is arranged on two corners of the positive plate close to one side of the positive output end, and the second avoiding corner is arranged along a third direction; the third avoiding corner is arranged on two corners of the positive plate close to one side of the negative output end, and the third avoiding corner is arranged along the third direction; the projection of the second avoiding corner and the third avoiding corner in a first plane is inside the projection of the first avoiding corner in the first plane, and the first plane is perpendicular to the first direction;

[0009] The cover plate assembly comprises a cover plate body and a first plastic part arranged on one side of the cover plate body close to the polar group and abutting against the polar group.

[0010] Optionally, the negative plate comprises two first side edges arranged opposite along a second direction and two second side edges arranged opposite along a third direction, and the first side edge and the second side edge are connected through the first avoiding corner;

[0011] The first avoiding corner comprises a first straight edge and a second straight edge, the first straight edge is connected with the first side edge, the second straight edge is connected with the second side edge, the second straight edge is perpendicular to the second side edge, and the first straight edge and the second side edge form an included angle β1;

[0012] The value range of β1 is 30°≤β1≤40°.

[0013] Optionally, one end of the first straight edge is connected with the first side edge through a first arc-shaped edge, the other end of the first straight edge is connected with the second straight edge through a second arc-shaped edge, the first arc-shaped edge intersects with the first side edge at a c1 point, the second straight edge intersects with the second arc-shaped edge at an a1 point, and the second straight edge intersects with the second side edge at a b1 point;

[0014] In the third direction, the distance between the a1 point and the second side edge is A1, and the distance between the c1 point and the second side edge is C1; in the second direction, the distance between the b1 point and the first side edge is B1; the radius of the first arc-shaped edge and the second arc-shaped edge is R1;

[0015] The value range of A1 is 1mm≤A1≤2mm.

[0016] The value range of B1 is 1.5mm≤B1≤3mm.

[0017] The value range of C1 is 3mm≤C1≤5mm.

[0018] R1 is in the range of 1mm≤R1≤1.5mm.

[0019] Optionally, the positive plate comprises a third side and a fourth side oppositely arranged along a second direction, and two fifth sides oppositely arranged along a third direction, the third side and the fifth side are connected through the second avoiding angle, and the fourth side and the fifth side are connected through the third avoiding angle.

[0020] The second avoiding angle comprises a third straight side and a fourth straight side, the third straight side is connected with the third side, the fourth straight side is connected with the fifth side, the fourth straight side is perpendicular to the fifth side, and the third straight side and the fifth side have an included angle β2 therebetween.

[0021] β2 is in the range of 30°≤β2≤40°.

[0022] The third avoiding angle comprises a fifth straight side and a sixth straight side, the fifth straight side is connected with the fourth side, the sixth straight side is connected with the fifth side, the sixth straight side is perpendicular to the fifth side, and the fifth straight side and the fifth side have an included angle β3 therebetween.

[0023] β3 is in the range of 30°≤β3≤40°.

[0024] Optionally, the third straight side and the fourth straight side are connected through a third arc-shaped side, the third straight side intersects with the third side at a c2 point, the fourth straight side intersects with the third arc-shaped side at an a2 point, and the fourth straight side intersects with the fifth side at a b2 point.

[0025] In the third direction, a distance between the a2 point and the fifth side is A2, and a distance between the c2 point and the fifth side is C2; in the second direction, a distance between the b2 point and the third side is B2; a radius of the third arc-shaped side is R2; wherein A2=A1, and R2=R1.

[0026] B2 is in the range of 5mm≤B2≤7mm.

[0027] C2 is in the range of 4mm≤C2≤6mm.

[0028] Optionally, the fifth straight side and the sixth straight side are connected through a fourth arc-shaped side, the fifth straight side intersects with the fourth side at a c3 point, the sixth straight side intersects with the fourth arc-shaped side at an a3 point, and the sixth straight side intersects with the fifth side at a b3 point.

[0029] Along the third direction, the distance between the point a3 and the fifth side is A3, and the distance between the point c3 and the fifth side is C3; along the second direction, the distance between the point b3 and the fourth side is B3; the radius of the fourth arc-shaped side is R3; wherein A3=A1, and R3=R1;

[0030] The value range of B3 is 3mm≤B3≤5mm.

[0031] The value range of C3 is 3mm≤C3≤5mm.

[0032] Optionally, the width of the negative electrode sheet along the third direction is greater than the width of the positive electrode sheet along the third direction, and the length of the negative electrode sheet along the second direction is greater than the length of the positive electrode sheet along the second direction.

[0033] Along the third direction, the distance between the second side of the negative electrode sheet and the fifth side of the positive electrode sheet is D1, and the value range of D1 is 1mm≤D1≤1.8mm.

[0034] Along the second direction, the distance between the first side of the negative electrode sheet close to the negative electrode output end and the fourth side of the positive electrode sheet is D2, and the value range of D2 is 2.5mm≤D2≤3.5mm.

[0035] Optionally, each negative electrode sheet is provided with a first lead-out part, and the first lead-out parts of all the negative electrode sheets are stacked and welded along the first direction to form the negative electrode output end; each positive electrode sheet is provided with a second lead-out part, and the second lead-out parts of all the positive electrode sheets are stacked and welded along the first direction to form the positive electrode output end.

[0036] Optionally, the positive electrode sheet comprises a base body and a positive electrode active layer, the second lead-out part and the base body are in an integral structure, the positive electrode active layer is coated on two end faces of the base body opposite along the first direction, and the positive electrode active layer forms a boundary line with the base body on the side provided with the second lead-out part.

[0037] Along the second direction, the distance between the first side of the negative electrode sheet close to the positive electrode output end and the boundary line is D3, and the value range of D3 is 1mm≤D3≤1.8mm.

[0038] Optionally, the length of the separator along the second direction is greater than the length of the negative electrode sheet along the second direction, the width of the separator along the third direction is greater than the width of the negative electrode sheet along the third direction, the separator comprises two sixth sides opposite along the second direction, and two seventh sides opposite along the third direction.

[0039] In the third direction, the distance between the seventh side edge of the diaphragm and the second side edge of the negative pole piece is E1; in the second direction, the distance between the sixth side edge of the diaphragm close to the negative pole output end and the first side edge of the negative pole piece close to the negative pole output end is E2, and the distance between the sixth side edge of the diaphragm close to the positive pole output end and the first side edge of the negative pole piece close to the positive pole output end is E3;

[0040] The value range of E1 is 1.5mm≤E1≤2.8mm;

[0041] The value range of E2 is 3.0mm≤E2≤4.5mm;

[0042] The value range of E3 is 3.5mm≤E3≤6.5mm.

[0043] The beneficial effects of the present application are:

[0044] The present application provides an electric core, comprising a pole group and a cover plate assembly, the pole group is arranged on one side of the cover plate assembly, the four corner portions of the negative pole piece of the pole group are each provided with a first avoiding corner, the two corner portions of the positive pole piece close to one side of the positive pole output end are each provided with a second avoiding corner, the two corner portions of the positive pole piece close to one side of the negative pole output end are each provided with a third avoiding corner, the edge of the projection of the second avoiding corner and the third avoiding corner in the first plane is located inside the edge of the projection of the first avoiding corner in the first plane. Through the arrangement of the first avoiding corner, the second avoiding corner and the third avoiding corner, the acting force between the first plastic part of the cover plate assembly and the corner portion of the pole group is small, the positive pole piece and the negative pole piece are prevented from being pressed and injured, and the safety of the electric core is good. BRIEF DESCRIPTION OF DRAWINGS

[0045] Figure 1 It is a structural schematic view of the electric core provided in the embodiment of the present application;

[0046] Figure 2 It is a front view of the negative pole piece provided in the embodiment of the present application;

[0047] Figure 3 It is a front view of the positive pole piece provided in the embodiment of the present application; Figure 2 It is a local enlarged view of the position I in the figure;

[0048] Figure 4 It is a front view of the positive pole piece provided in the embodiment of the present application;

[0049] Figure 5 It is a local enlarged view of the position II in the figure; Figure 4

[0050] It is a local enlarged view of the position III in the figure; Figure 6 Figure 4 It is a local enlarged view of the position III in the figure;

[0051] Figure 7 ​A front view of a pole group provided in an embodiment of the present application;

[0052] Figure 8 A front view of a pole group provided in an embodiment of the present application; Figure 7 A partial enlarged view of a portion IV in the figure;

[0053] Figure 9 A front view of a pole group provided in an embodiment of the present application; Figure 7 A partial enlarged view of a portion V in the figure.

[0054] In the figure:

[0055] 100, pole group; 110, negative pole piece; 111, first avoiding angle; 1111, first straight side; 1112, second straight side; 1113, first arc-shaped side; 1114, second arc-shaped side; 112, first side; 113, second side; 114, first lead-out part; 120, positive pole piece; 1201, base body; 1202, positive pole active layer; 1203, boundary line; 121, second avoiding angle; 1211, third straight side; 1212, fourth straight side; 1213, third arc-shaped side; 122, third avoiding angle; 1221, fifth straight side; 1222, sixth straight side; 1223, fourth arc-shaped side; 123, third side; 124, fourth side; 125, fifth side; 126, second lead-out part; 130, diaphragm; 131, sixth side; 132, seventh side;

[0056] 200, cover plate assembly; 210, cover plate body; 220, first plastic piece; 221, plastic piece body; 222, support part; 230, pole; 240, second plastic piece; 250, connecting block. DETAILED DESCRIPTION

[0057] The technical solutions of the present application will be described clearly and completely below in conjunction with the drawings. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0058] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", and the like indicate the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second", are only for the purpose of description, and cannot be understood as indicating or implying relative importance. Among them, the terms "first position" and "second position" are two different positions, and moreover, the "above", "over" and "on" of the first feature to the second feature include the first feature above and obliquely above the second feature, or only indicate that the first feature is higher than the second feature in horizontal height. The "below", "under" and "under" of the first feature to the second feature include the first feature below and obliquely below the second feature, or only indicate that the first feature is lower than the second feature in horizontal height.

[0059] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0060] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the drawings, wherein the same or similar reference numerals represent the same or similar elements or elements with the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary and are only used to explain the present application, and cannot be understood as a limitation on the present application.

[0061] As shown in Figure 1 , Figure 2 , Figure 4 and Figure 7 , the present embodiment provides a battery cell, which comprises a pole group 100, two cover plate assemblies 200 and a shell. The shell is provided with two openings at both ends in the length direction, one cover plate assembly 200 is connected at each opening, and the pole group 100 is arranged in the shell.

[0062] The cover plate assembly 200 comprises a cover plate body 210 and a first plastic part 220 arranged on the side of the cover plate body 210 close to the pole group 100 and abutting against the pole group 100, so that the pole group 100 is tightly fixed in the shell. The pole group 100 comprises a negative pole sheet 110, a positive pole sheet 120 and a diaphragm 130, the positive pole sheet 120 and the negative pole sheet 110 are arranged in a stack along a first direction, and the diaphragm 130 is arranged between the positive pole sheet 120 and the negative pole sheet 110. The pole group 100 has a positive output end and a negative output end at both ends along a second direction (i.e. the length direction of the shell). The two corners of the negative pole sheet 110 close to the side of the positive output end and the two corners of the negative pole sheet 110 close to the side of the negative output end are each provided with a first avoiding corner 111. The two corners of the positive pole sheet 120 close to the side of the positive output end are each provided with a second avoiding corner 121, and the two second avoiding corners 121 are arranged in a space along a third direction. The two corners of the positive pole sheet 120 close to the side of the negative output end are each provided with a third avoiding corner 122, and the two third avoiding corners 122 are arranged in a space along the third direction. The projection of the second avoiding corner 121 and the third avoiding corner 122 in a first plane is inside the projection of the first avoiding corner 111 in the first plane, and the first plane is perpendicular to the first direction. The first direction is the Z-axis direction shown in Figure 1 , the second direction is the X-axis direction shown in Figure 1 , and the third direction is the Y-axis direction shown in Figure 1 .

[0063] The first plastic part 220 comprises a plastic part body 221 and two support parts 222 connected to the two ends of the plastic part body 221 along the third direction, and the support part 222 is arranged on the side of the plastic part body 221 close to the pole group 100 and used for abutting against the pole group 100. The support part 222 of the first plastic part 220 has a good supporting and fixing effect on the pole group 100. The first avoiding corner 111, the second avoiding corner 121 and the third avoiding corner 122 are arranged to make the force between the support part 222 of the first plastic part 220 and the corners of the pole group 100 smaller, so as to avoid the positive pole sheet 120 and the negative pole sheet 110 being damaged when the cover plate assembly 200 presses the pole group 100 into the shell, the assembly yield is higher, and the safety performance of the battery cell is good.

[0064] The cover plate assembly 200 further comprises a pole column 230, a second plastic part 240 and a connecting block 250, the second plastic part 240 is located on the side of the cover plate body 210 away from the first plastic part 220, the connecting block 250 is located on the side of the second plastic part 240 away from the cover plate body 210, and the pole column 230 is riveted with the connecting block 250 after penetrating through the first plastic part 220, the cover plate body 210, the second plastic part 240 and the connecting block 250, so as to fix the pole column 230 on the cover plate body 210, and the first plastic part 220 and the second plastic part 240 have an insulating effect.

[0065] Further, the two cover plate assemblies 200 in the embodiment are respectively a positive cover plate and a negative cover plate, the pole 230 on the positive cover plate is a positive pole, the pole 230 on the negative cover plate is a negative pole, the positive pole is electrically connected with the positive output end of the pole group 100, and the negative pole is electrically connected with the negative output end of the pole group 100.

[0066] Referring to Figure 2 and Figure 3 The negative sheet 110 includes two first side edges 112 oppositely arranged along a second direction and two second side edges 113 oppositely arranged along a third direction, and the first side edge 112 and the second side edge 113 are transitioned through a first avoiding angle 111. The first avoiding angle 111 includes a first straight edge 1111 and a second straight edge 1112, the first straight edge 1111 is connected with the first side edge 112, the second straight edge 1112 is connected with the second side edge 113, the second straight edge 1112 is perpendicular to the second side edge 113, and the first straight edge 1111 and the second side edge 113 have an included angle β1. Optionally, the value of β1 is in the range of 30°≤β1≤40°. For example, the value of β1 can be 30°, 32°, 34°, 36°, 38° or 40°, etc. By having the included angle β1 between the first straight edge 1111 and the second side edge 113, the support part 222 of the first plastic part 220 is prevented from excessively pressing the negative sheet 110, so as to avoid the pole group 100 being pressed and damaged.

[0067] As an optional solution, one end of the first straight edge 1111 and the first side edge 112 are transitioned through a first arc-shaped edge 1113. By arranging the first arc-shaped edge 1113, the connection between the first straight edge 1111 and the first side edge 112 is relatively smooth and gentle, avoiding the connection between the first straight edge 1111 and the first side edge 112 forming a sharp angle, which causes the damage of the insulating film wrapped outside the pole group 100. The other end of the first straight edge 1111 and the second straight edge 1112 are transitioned through a second arc-shaped edge 1114. By arranging the second arc-shaped edge 1114, the connection between the first straight edge 1111 and the second straight edge 1112 is relatively smooth and gentle, facilitating the processing and forming.

[0068] The first arc-shaped side 1113 intersects the first side 112 at a c1 point, the second straight side 1112 intersects the second arc-shaped side 1114 at an a1 point, and the second straight side 1112 intersects the second side 113 at a b1 point. In the third direction, the distance between the a1 point and the second side 113 is A1, and the value of A1 is in the range of 1mm≤A1≤2mm. For example, the value of A1 can be 1mm, 1.2mm, 1.4mm, 1.6mm, 1.8mm or 2.0mm, etc. In the third direction, the distance between the c1 point and the second side 113 is C1, and the value of C1 is in the range of 3mm≤C1≤5mm. For example, the value of C1 can be 3mm, 3.5mm, 4.0mm, 4.5mm or 5.0mm, etc. In the second direction, the distance between the b1 point and the first side 112 is B1, and the value of B1 is in the range of 1.5mm≤B1≤3mm. For example, the value of B1 can be 1.5mm, 2.0mm, 2.5mm or 3.0mm, etc.

[0069] The radius of the first arc-shaped side 1113 and the second arc-shaped side 1114 is R1, and the value of R1 is in the range of 1mm≤R1≤1.5mm. For example, the value of R1 can be 1mm, 1.2mm, 1.4mm or 1.5mm, etc. By setting the first arc-shaped side 1113, the transition between the first straight side 1111 and the first side 112 is smoother. By setting the second arc-shaped side 1114, the transition between the first straight side 1111 and the second straight side 1112 is smoother. It should be noted that the value of R1 should not be too large, otherwise the size of the first avoidance angle 111 will be set to be larger, and the corner of the negative plate 110 will be cut off more, and the capacity of the pole group 100 will decrease; the value of R1 should not be too small, otherwise the angle formed at the connection between the first straight side 1111 and the first side 112 and the connection between the first straight side 1111 and the second straight side 1112 is still relatively sharp.

[0070] Referring to Figure 4 and Figure 5The positive plate 120 includes a third side edge 123 and a fourth side edge 124 oppositely arranged along the second direction, and two fifth side edges 125 oppositely arranged along the third direction. The third side edge 123 and the fifth side edge 125 are transitioned through a second avoiding angle 121, and the fourth side edge 124 and the fifth side edge 125 are transitioned through a third avoiding angle 122. The second avoiding angle 121 includes a third straight edge 1211 connected with the third side edge 123, and a fourth straight edge 1212 connected with the fifth side edge 125. The fourth straight edge 1212 is perpendicular to the fifth side edge 125, and an included angle β2 is formed between the third straight edge 1211 and the fifth side edge 125. The value of β2 is in the range of 30°≤β2≤40°. For example, the value of β2 can be 30°, 32°, 34°, 36°, 38° or 40°, etc. By forming the included angle β2 between the third straight edge 1211 and the fifth side edge 125, the support part 222 of the first plastic part 220 does not excessively press the side of the positive plate 120 provided with the positive output end, so that the pole group 100 is not damaged.

[0071] Further, the third straight edge 1211 and the fourth straight edge 1212 are transitioned through a third arc-shaped edge 1213. The third arc-shaped edge 1213 is arranged to make the connection between the third straight edge 1211 and the fourth straight edge 1212 smooth and gentle, which is convenient for processing and forming. The radius of the third arc-shaped edge 1213 is R2, and R2=R1. In this way, the size of the second avoiding angle 121 is reasonably designed, the corner part of the positive plate 120 is not excessively cut, the capacity of the pole group 100 is not reduced, and the second avoiding angle 121 is also convenient for processing and forming.

[0072] The third straight edge 1211 and the third side edge 123 intersect at a c2 point, the fourth straight edge 1212 and the third arc-shaped edge 1213 intersect at an a2 point, and the fourth straight edge 1212 and the fifth side edge 125 intersect at a b2 point. Along the third direction, the distance between the a2 point and the fifth side edge 125 is A2, and A2=A1. The distance between the c2 point and the fifth side edge 125 is C2, and the value of C2 is in the range of 4mm≤C2≤6mm. For example, the value of C2 can be 4.0mm, 4.5mm, 5.0mm, 5.5mm or 6.0mm, etc. Along the second direction, the distance between the b2 point and the third side edge 123 is B2, and the value of B2 is in the range of 5mm≤B2≤7mm. For example, the value of B2 can be 5.0mm, 5.5mm, 6.0mm, 6.5mm or 7.0mm, etc.

[0073] Referring to Figure 6The third avoiding angle 122 includes a fifth straight side 1221 and a sixth straight side 1222. The fifth straight side 1221 is connected with the fourth side 124, and the sixth straight side 1222 is connected with the fifth side 125. The sixth straight side 1222 is perpendicular to the fifth side 125. The fifth straight side 1221 and the fifth side 125 form an included angle β3. The value of β3 is in the range of 30°≤β3≤40°. For example, the value of β3 can be 30°, 32°, 34°, 36°, 38° or 40°, etc. By forming the included angle β3 between the fifth straight side 1221 and the fifth side 125, the support part 222 of the first plastic part 220 does not excessively press the side of the positive plate 120 away from the positive output end, so that the pole group 100 is not pressed and injured.

[0074] The fifth straight side 1221 and the sixth straight side 1222 are connected by a fourth arc side 1223. The fifth straight side 1221 intersects with the fourth side 124 at a c3 point. The distance between the c3 point and the fifth side 125 is C3. The value of C3 is in the range of 3mm≤C3≤5mm. For example, the value of C3 can be 3.0mm, 3.5mm, 4.0mm, 4.5mm or 5.0mm, etc. The sixth straight side 1222 intersects with the fourth arc side 1223 at an a3 point. Along the third direction, the distance between the a3 point and the fifth side 125 is A3, and A3=A2=A1. The sixth straight side 1222 intersects with the fifth side 125 at a b3 point. Along the second direction, the distance between the b3 point and the fourth side 124 is B3, and the value of B3 is in the range of 3mm≤B3≤5mm. For example, the value of B3 can be 3.0mm, 3.5mm, 4.0mm, 4.5mm or 5.0mm, etc.

[0075] The size limits of A1, B1, C1, A2, B2, C2, A3, B3 and C3 make the first avoiding angle 111, the second avoiding angle 121 and the third avoiding angle 122 form a staggered position, change the stress condition of the corner of the pole group 100 when the support part 222 of the first plastic part 220 abuts against the pole group 100, reduce the stress of the corner of the positive plate 120 and the negative plate 110, avoid the corner of the pole group 100 being pressed and injured by the first plastic part 220, and facilitate the lamination. In addition, the size limits of A1, B1, C1, A2, B2, C2, A3, B3 and C3 also make the second avoiding angle 121 and the third avoiding angle 122 be located inside the first avoiding angle 111, and the negative plate 110 can cover the positive plate 120, which is beneficial to improve the capacity and charge-discharge performance of the pole group 100.

[0076] Further, the radius of the fourth arc side 1223 is R3, and R3=R2=R1. In this way, the size design of the third avoiding angle 122 is reasonable, the corner of the positive plate 120 is not excessively cut, the capacity of the pole group 100 is not reduced, and the third avoiding angle 122 is also convenient to process and form.

[0077] Generally, the negative sheet 110 includes a copper foil, and a negative active layer is coated on the copper foil, the negative active layer is coated on two end faces of the copper foil along the first direction, the positive sheet 120 includes a substrate 1201 and a positive active layer 1202, the substrate 1201 is an aluminum foil, and the positive active layer 1202 is coated on two opposite end faces of the aluminum foil along the first direction, the positive sheet 120 is stacked with the negative sheet 110 along the first direction, and the positive active layer 1202 and the negative active layer are insulated and separated by the separator 130. The charging and discharging of the battery pack 100 are realized through the chemical reaction of the positive active layer 1202, the negative active layer and the electrolyte.

[0078] Referring to Figures 7-9 , the width of the negative sheet 110 along the third direction is greater than the width of the positive sheet 120 along the third direction, and the length of the negative sheet 110 along the second direction is greater than the length of the positive sheet 120 along the second direction. That is, the width of the copper foil along the third direction is greater than the width of the aluminum foil along the third direction, and the length of the copper foil along the second direction is greater than the length of the aluminum foil along the second direction. The negative active layer covers the opposite end faces of the copper foil along the first direction, and the opposite end faces of the aluminum foil along the first direction have a long strip-shaped area (shown in the shadow part in FIG. 12) on the side where the positive output end is provided, which is not coated with the positive active layer 1202, and the rest of the opposite end faces of the aluminum foil along the first direction is covered with the positive active layer 1202, so as to ensure that the positive active layer 1202 can be completely covered by the negative active layer in the first plane. Figure 8

[0079] Along the third direction, the distance between the second side edge 113 of the negative sheet 110 and the fifth side edge 125 of the positive sheet 120 is D1, and the value of D1 is in the range of 1mm≤D1≤1.8mm. For example, the value of D1 can be 1.0mm, 1.2mm, 1.4mm, 1.6mm or 1.8mm, etc. By limiting the value of D1 in the above range, it is ensured that the edge of the negative active layer of the negative sheet 110 along the third direction can exceed the edge of the positive active layer 1202 of the positive sheet 120 along the third direction. Along the second direction, the distance between the first side edge 112 of the negative sheet 110 close to the negative output end and the fourth side edge 124 of the positive sheet 120 is D2, and the value of D2 is in the range of 2.5mm≤D2≤3.5mm. For example, the value of D2 can be 2.5mm, 3.0mm or 3.5mm, etc. By limiting the value of D2 in the above range, it is ensured that the edge of the negative active layer of the negative sheet 110 along the second direction on the side where the negative output end is provided can exceed the edge of the positive active layer 1202 of the positive sheet 120 along the second direction.

[0080] ​Further, the plurality of positive electrode sheets 120, the plurality of negative electrode sheets 110 and the plurality of separators 130 are provided, the plurality of positive electrode sheets 120 and the plurality of negative electrode sheets 110 are alternately and stacked along the first direction, and one separator 130 is provided between adjacent positive electrode sheet 120 and negative electrode sheet 110. Each negative electrode sheet 110 is provided with a first lead-out portion 114, the first lead-out portion 114 is in an integral structure with the copper foil, and the first lead-out portion 114 can be formed by cutting the copper foil. It should be noted that the first lead-out portion 114 is not coated with the negative active layer. The first lead-out portions 114 of all negative electrode sheets 110 are stacked and welded along the first direction to form a negative output end, and the negative output end bears the function of outputting current. Each positive electrode sheet 120 is provided with a second lead-out portion 126, the second lead-out portion 126 is in an integral structure with the aluminum foil, and the second lead-out portion 126 can be formed by cutting the aluminum foil (i.e. the substrate 1201). It should be noted that the second lead-out portion 126 is not coated with the positive active layer 1202. The second lead-out portions 126 of all positive electrode sheets 120 are stacked and welded along the first direction to form a positive output end, and the positive output end bears the function of inputting current. Among them, the positive electrode sheet 120 is responsible for storing and releasing electric energy, and the negative electrode sheet 110 generates electric energy through chemical reaction, so as to parallelly connect multiple positive electrode sheets 120 and negative electrode sheets to form the electrode group 100, thereby improving the capacity of the battery cell.

[0081] Continuing to refer to Figure 8 and Figure 9 , the positive active layer 1202 forms a boundary line 1203 with the substrate 1201 on the side where the second lead-out portion 126 is provided. Along the second direction, the distance between the first side edge 112 of the negative electrode sheet 110 close to the positive output end and the boundary line 1203 is D3, and the value of D3 is in the range of 1mm≤D3≤1.8mm. For example, the value of D3 can be 1.0mm, 1.2mm, 1.4mm, 1.6mm or 1.8mm, etc. By limiting the value of D3 within the above range, it is ensured that on the side where the positive output end is provided, the edge of the positive active layer 1202 of the positive electrode sheet 120 along the second direction will not exceed the edge of the negative active layer of the negative electrode sheet 110 along the second direction.

[0082] Further, the length of the separator 130 along the second direction is greater than the length of the negative electrode sheet 110 along the second direction, and the width of the separator 130 along the third direction is greater than the width of the negative electrode sheet 110 along the third direction. The separator 130 includes two sixth side edges 131 oppositely arranged along the second direction, and two seventh side edges 132 oppositely arranged along the third direction. The separator 130 ensures good insulation effect between the positive electrode sheet 120 and the negative electrode sheet 110, prevents short circuit, and allows electrolyte to permeate freely, thereby ensuring safe and stable operation of the battery.

[0083] In the third direction, the distance between the seventh side edge 132 of the diaphragm 130 and the second side edge 113 of the negative plate 110 is E1, and the value of E1 is in the range of 1.5mm≤E1≤2.8mm. For example, the value of E1 can be 1.5mm, 1.8mm, 2.0mm, 2.5mm or 2.8mm, etc. By limiting the value of E1 in the above range, it is ensured that the edge of the diaphragm 130 in the third direction can exceed the edge of the negative active layer of the negative plate 110 in the third direction, and the insulation effect is good. In the second direction, the distance between the sixth side edge 131 of the diaphragm 130 close to the negative output end and the first side edge 112 of the negative plate 110 close to the negative output end is E2, and the value of E2 is in the range of 3.0mm≤E2≤4.5mm. For example, the value of E2 can be 3.0mm, 3.5mm, 4.0mm or 4.5mm, etc. By limiting the value of E2 in the above range, it is ensured that on the side provided with the negative output end, the edge of the diaphragm 130 in the second direction can exceed the edge of the negative active layer of the negative plate 110 in the second direction, and the insulation effect is good.

[0084] The distance between the sixth side edge 131 of the diaphragm 130 close to the positive output end and the first side edge 112 of the negative plate 110 close to the positive output end is E3, and the value of E3 is in the range of 3.5mm≤E3≤6.5mm. For example, the value of E3 can be 3.5mm, 4.0mm, 4.5mm, 5.0mm, 5.5mm or 6.5mm, etc. By limiting the value of E3 in the above range, it is ensured that on the side provided with the positive output end, the edge of the positive active layer 1202 in the second direction will not exceed the edge of the diaphragm 130 in the second direction, and the edge of the negative active layer of the negative plate 110 in the second direction will not exceed the edge of the diaphragm 130 in the second direction, and the insulation effect is good.

[0085] In the following, the values of the above-mentioned parameters of the battery cell are verified by samples in some specific implementation cases, the influence of the size design of the above-mentioned parameters on the crushing of the pole group 100 is explored, and the rationality of the above parameter design is judged. For details, see Table 1.

[0086] Table 1

[0087]

[0088] From the above results, it can be seen that the parameters A1, B1, C1, R1, A2, B2, C2, R2, A3, B3, C3, R3, D1, D2, D3 in Examples 1 to 10 all meet the corresponding size limit. After CT detection, during the battery cell assembly process (i.e. when the first plastic part 220 and the pole group 100 are put into the shell), the positive plate 120 and the negative plate 110 of the pole group 100 are not crushed, the battery cell assembly yield is high, the battery cell product is good, and failure is not easy to occur.

[0089] The value of B1 in Comparative Example 1 exceeds the lower limit of its value range 1.5mm≤B1≤3mm, and other parameters are normally valued within their value ranges. After CT detection, during the assembly of the battery cell (i.e., when the first plastic part 220 and the pole group 100 enter the shell), the pole group 100 is pressed and damaged, the assembly yield of the battery cell is low, and the battery cell product is defective.

[0090] The value of C1 in Comparative Example 2 exceeds the lower limit of its value range 3mm≤C1≤5mm, and other parameters are normally valued within their value ranges. After CT detection, during the assembly of the battery cell (i.e., when the first plastic part 220 and the pole group 100 enter the shell), the pole group 100 is pressed and damaged, the assembly yield of the battery cell is low, and the battery cell product is defective.

[0091] In Comparative Example 3, the value of B2 exceeds the lower limit of its value range 5mm≤B2≤7mm, and the value of C2 exceeds the lower limit of its value range 4mm≤C2≤6mm, and other parameters are normally valued within their value ranges. After CT detection, during the assembly of the battery cell (i.e., when the first plastic part 220 and the pole group 100 enter the shell), the pole group 100 is pressed and damaged, the assembly yield of the battery cell is low, and the battery cell product is defective.

[0092] In Comparative Example 4, the value of B3 exceeds the lower limit of its value range 3mm≤B3≤5mm, and the value of C3 exceeds the lower limit of its value range 3mm≤C3≤5mm, and other parameters are normally valued within their value ranges. After CT detection, during the assembly of the battery cell (i.e., when the first plastic part 220 and the pole group 100 enter the shell), the pole group 100 is pressed and damaged, the assembly yield of the battery cell is low, and the battery cell product is defective.

[0093] In summary, when the parameters A1, B1, C1, R1, A2, B2, C2, R2, A3, B3, C3, R3, D1, D2, and D3 all meet their respective size restrictions, the problem of the corner of the pole group 100 being pressed and damaged by the first plastic part 220 can be effectively avoided, greatly improving the process yield and safety performance of the battery cell.

[0094] Obviously, the above embodiments of the present application are only examples for clear illustration of the present application, and are not a limitation on the embodiments of the present application. Based on the above description, other different forms of changes or variations can be made by those of ordinary skill in the art. Here, it is not necessary or possible to exhaust all embodiments. Any modification, equivalent replacement, and improvement made within the spirit and principles of the present application shall be included in the protection scope of the claims of the present application.

Claims

1. A battery cell, characterized in that, include: An electrode assembly includes a negative electrode, a positive electrode, and a separator. The positive and negative electrode are stacked along a first direction, and the separator is sandwiched between the positive and negative electrode. The electrode assembly has a positive output terminal and a negative output terminal at both ends along a second direction. The negative electrode sheet has two corners near the positive output terminal and two corners near the negative output terminal, each with a first clearance angle; the positive electrode sheet has two corners near the positive output terminal, each with a second clearance angle, the two second clearance angles being spaced apart along a third direction; the positive electrode sheet has two corners near the negative output terminal, each with a third clearance angle, the two third clearance angles being spaced apart along a third direction; the edges of the projections of the second clearance angles and the third clearance angles in a first plane are located inside the edges of the projections of the first clearance angles in the first plane, and the first plane is perpendicular to the first direction; A cover plate assembly includes a cover plate body and a first plastic part, wherein the first plastic part is disposed on the side of the cover plate body near the electrode group and abuts against the electrode group; The negative electrode includes two first side edges arranged opposite each other along a second direction, and two second side edges arranged opposite each other along a third direction, wherein the first side edges and the second side edges are transitioned by the first clearance angle; The first avoidance angle includes a first straight side and a second straight side. The first straight side is connected to the first side, and the second straight side is connected to the second side. The second straight side is perpendicular to the second side, and there is an included angle β1 between the first straight side and the second side. The range of values ​​for β1 is: 30°≤β1≤40°; One end of the first straight edge transitions to the first side edge through a first arc edge, and the other end of the first straight edge transitions to the second straight edge through a second arc edge. The first arc edge intersects with the first side edge at point c1, the second straight edge intersects with the second arc edge at point a1, and the second straight edge intersects with the second side edge at point b1. Along the third direction, the distance between point a1 and the second side is A1, and the distance between point c1 and the second side is C1; along the second direction, the distance between point b1 and the first side is B1; the radius of the first arc side and the second arc side is R1. The range of values ​​for A1 is: 1mm ≤ A1 ≤ 2mm; The value range of B1 is: 1.5mm≤B1≤3mm; The value range of C1 is: 3mm≤C1≤5mm; The range of R1 is: 1mm ≤ R1 ≤ 1.5mm; The positive electrode includes a third side and a fourth side disposed opposite to each other along a second direction, and two fifth sides disposed opposite to each other along a third direction. The third side and the fifth side are connected by a second avoidance angle, and the fourth side and the fifth side are connected by the third avoidance angle. The second avoidance angle includes a third straight side and a fourth straight side. The third straight side is connected to the third side, and the fourth straight side is connected to the fifth side. The fourth straight side is perpendicular to the fifth side, and there is an included angle β2 between the third straight side and the fifth side. The range of values ​​for β2 is: 30°≤β2≤40°; The third avoidance angle includes a fifth straight side and a sixth straight side. The fifth straight side is connected to the fourth side, and the sixth straight side is connected to the fifth side. The sixth straight side is perpendicular to the fifth side, and there is an included angle β3 between the fifth straight side and the fifth side. The range of values ​​for β3 is: 30°≤β3≤40°; The third straight edge and the fourth straight edge transition through the third arc edge. The third straight edge intersects the third side edge at point c2. The fourth straight edge intersects the third arc edge at point a2. The fourth straight edge intersects the fifth side edge at point b2. Along the third direction, the distance between point a2 and the fifth side is A2, and the distance between point c2 and the fifth side is C2; along the second direction, the distance between point b2 and the third side is B2; the radius of the third arc side is R2; where A2=A1, R2=R1; The value range of B2 is: 5mm≤B2≤7mm; The value range of C2 is: 4mm≤C2≤6mm; The fifth straight edge and the sixth straight edge transition through the fourth arc edge. The fifth straight edge intersects the fourth side edge at point c3, the sixth straight edge intersects the fourth arc edge at point a3, and the sixth straight edge intersects the fifth side edge at point b3. Along the third direction, the distance between point a3 and the fifth side is A3, and the distance between point c3 and the fifth side is C3; along the second direction, the distance between point b3 and the fourth side is B3; the radius of the fourth arc-shaped side is R3; where A3=A1, R3=R1; The value range of B3 is: 3mm≤B3≤5mm; The value range of C3 is: 3mm≤C3≤5mm.

2. The battery cell according to claim 1, characterized in that, The width of the negative electrode sheet along the third direction is greater than the width of the positive electrode sheet along the third direction, and the length of the negative electrode sheet along the second direction is greater than the length of the positive electrode sheet along the second direction. Along a third direction, the distance between the second side of the negative electrode and the fifth side of the positive electrode is D1, and the value of D1 is in the range of 1mm≤D1≤1.8mm; Along the second direction, the distance between the first side of the negative electrode near the negative output terminal and the fourth side of the positive electrode is D2, and the value of D2 is in the range of 2.5mm≤D2≤3.5mm.

3. The battery cell according to claim 1, characterized in that, Each of the negative electrode plates is provided with a first lead-out portion, and the first lead-out portions of all the negative electrode plates are stacked and welded together along a first direction to form the negative electrode output terminal; each of the positive electrode plates is provided with a second lead-out portion, and the second lead-out portions of all the positive electrode plates are stacked and welded together along a first direction to form the positive electrode output terminal.

4. The battery cell according to claim 3, characterized in that, The positive electrode sheet includes a substrate and a positive electrode active layer. The second lead-out portion is an integral structure with the substrate. The positive electrode active layer is coated on two opposite end faces of the substrate along a first direction. The positive electrode active layer forms a boundary line with the substrate on the side where the second lead-out portion is located. Along the second direction, the distance between the first side of the negative electrode near the positive output terminal and the dividing line is D3, and the value range of D3 is: 1mm≤D3≤1.8mm.

5. The battery cell according to claim 1, characterized in that, The length of the separator along the second direction is greater than the length of the negative electrode sheet along the second direction, and the width of the separator along the third direction is greater than the width of the negative electrode sheet along the third direction. The separator includes two sixth side edges arranged opposite to each other along the second direction and two seventh side edges arranged opposite to each other along the third direction. Along the third direction, the distance between the seventh side of the diaphragm and the second side of the negative electrode is E1; along the second direction, the distance between the sixth side of the diaphragm near the negative electrode output terminal and the first side of the negative electrode near the negative electrode output terminal is E2, and the distance between the sixth side of the diaphragm near the positive electrode output terminal and the first side of the negative electrode near the positive electrode output terminal is E3; The value range of E1 is: 1.5mm ≤ E1 ≤ 2.8mm; The value range of E2 is: 3.0mm≤E2≤4.5mm; The value range of E3 is: 3.5mm≤E3≤6.5mm.

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