Cylindrical battery cell and electric equipment

Abstract

The invention provides a cylindrical battery cell and electric equipment, the cylindrical battery cell comprises an electrode assembly with a winding structure and gummed paper, the electrode assembly comprises a first pole piece and a second pole piece which are opposite in polarity, the outermost ring of the first pole piece is located on the outer side of the outermost ring of the second pole piece, and the gummed paper is located between the first pole piece and the second pole piece. The outermost ring of the first pole piece comprises a double-sided coating area and a single-sided coating area, and one end, far away from the double-sided coating area, of the single-sided coating area is a winding ending end of the first pole piece. The gummed paper is wound on the periphery of the electrode assembly, the gummed paper is provided with a starting section and an ending section, the starting section and the ending section are overlapped to form an overlapped part, the projection of the single-side coating area on the gummed paper is overlapped with the overlapped part from the winding center of the electrode assembly to the outside, and the projection of the double-side coating area on the gummed paper is not overlapped with the overlapped part. By adopting the scheme, the risk of breakage of the current collector can be reduced, so that the safety of the cylindrical battery cell is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of batteries, in particular to a cylindrical battery cell and an electric device. BACKGROUND

[0002] At present, with the rapid development of new energy technology, battery cells have been widely used in the fields of electronic devices, electric vehicles, electric two-wheel vehicles, electric tools, etc. With the more and more extensive application of battery cells, higher requirements are put forward for the safety of battery cells. SUMMARY

[0003] The present application provides a cylindrical battery cell and an electric device, which can improve the safety of the cylindrical battery cell.

[0004] In a first aspect, the present application provides a cylindrical battery cell, the cylindrical battery cell comprising an electrode assembly having a winding structure and a gum paper, the electrode assembly comprising first and second pole pieces having opposite polarities, an outermost circle of the first pole piece being located outside an outermost circle of the second pole piece, the outermost circle of the first pole piece comprising a double-coated area and a single-coated area, an end of the single-coated area away from the double-coated area being a winding end of the first pole piece. The gum paper is wound around an outer periphery of the electrode assembly, the gum paper having a starting section and an ending section, the starting section and the ending section overlapping and forming an overlapping portion, from a winding center of the electrode assembly outward, a projection of the single-coated area on the gum paper overlaps the overlapping portion, and a projection of the double-coated area on the gum paper does not overlap the overlapping portion.

[0005] In the above technical solution, by winding the gum paper around the outer periphery of the electrode assembly, the gum paper has a starting section and an ending section, the starting section and the ending section overlap and form an overlapping portion, so that the gum paper can provide a better binding effect to the electrode assembly, the electrode assembly can maintain a better winding state, so that the charging and discharging process of the cylindrical battery cell is more stable, and the safety of the cylindrical battery cell is higher.

[0006] Since the active material layer will expand and shrink during the charging and discharging process of the battery cell, the expansion amounts of the single-coated area and the double-coated area are different, so that the current collector at the junction area of the single-coated area and the double-coated area has a risk of breaking. Since the overlapping portion of the gum paper has a larger thickness than other parts, by making the projection of the single-coated area on the gum paper overlap the overlapping portion and the projection of the double-coated area on the gum paper not overlap the overlapping portion from the winding center of the electrode assembly outward, the overlapping portion can provide a larger support force to the single-coated area than the double-coated area, thereby balancing the difference between the expansion forces of the single-coated area and the double-coated area, reducing the problem of stress concentration at the junction of the single-coated area and the double-coated area, reducing the risk of breaking of the current collector, and thereby improving the safety of the cylindrical battery cell.

[0007] In some embodiments of the present application, along the winding direction of the electrode assembly, the width of the overlapping portion is W1, and 1mm≤W1≤15mm.

[0008] In the above technical solution, when W1 is greater than or equal to 1 mm, the width of the overlapping part is not too small, the supporting force of the overlapping part on the single-coated area is greater, the difference between the expansion forces of the single-coated area and the double-coated area is further reduced, the problem of stress concentration at the junction of the single-coated area and the double-coated area is further reduced, the risk of the current collector breaking is reduced, and the safety of the cylindrical battery cell is further improved. The adhesion of the adhesive paper to the electrode assembly is greater, the risk of metal ion precipitation caused by the misalignment of the first and second pole pieces in the winding axis direction of the electrode assembly is reduced, and the safety of the battery cell is improved. When W1 is less than or equal to 15 mm, the width of the overlapping part is not too large, the space occupied by the overlapping part is small, the volume of the electrode assembly can be reduced, the electrode assembly can be easily loaded into the shell of the cylindrical battery cell, and the shell entry rate of the electrode assembly is improved. Therefore, when 1 mm≤W1≤15 mm, the difference between the expansion forces of the single-coated area and the double-coated area can be further reduced, the problem of stress concentration at the junction of the single-coated area and the double-coated area is further reduced, the risk of the current collector breaking is reduced, and the safety of the cylindrical battery cell is further improved. The adhesion of the adhesive paper to the electrode assembly is greater, the risk of metal ion precipitation caused by the misalignment of the first and second pole pieces in the winding axis direction of the electrode assembly is reduced, and the safety of the battery cell is improved. The volume of the cylindrical battery cell can be reduced, and the shell entry rate of the electrode assembly is improved.

[0009] In some embodiments of the present application, 3 mm≤W1≤8 mm.

[0010] In the technical solution, when W1 is greater than or equal to 3 mm, the width of the overlapping part is further not too small, the supporting force of the overlapping part on the single-side coating area is greater, the difference between the expansion forces of the single-side coating area and the double-side coating area is further reduced, the problem of stress concentration at the junction of the single-side coating area and the double-side coating area is further reduced, the risk of breaking of the current collector is reduced, and the safety of the cylindrical battery cell is further improved. Furthermore, the adhesive tape has a greater bonding force on the electrode assembly, the risk of metal ion precipitation caused by the misalignment of the first and second electrode tabs in the winding axis direction of the electrode assembly is reduced, and the safety of the battery cell is further improved. When W1 is less than or equal to 8 mm, the width of the overlapping part is further not too large, the space occupied by the overlapping part is smaller, the volume of the electrode assembly can be reduced, the electrode assembly can be easily loaded into the shell of the cylindrical battery cell, and the shell loading rate of the electrode assembly is improved. Therefore, when 3 mm≤W1≤8 mm, the difference between the expansion forces of the single-side coating area and the double-side coating area is further reduced, the problem of stress concentration at the junction of the single-side coating area and the double-side coating area is further reduced, the risk of breaking of the current collector is reduced, and the safety of the cylindrical battery cell is further improved. Furthermore, the adhesive tape has a greater bonding force on the electrode assembly, the risk of metal ion precipitation caused by the misalignment of the first and second electrode tabs in the winding axis direction of the electrode assembly is reduced, and the safety of the battery cell is further improved. In addition, the volume of the cylindrical battery cell is further reduced, and the shell loading rate of the electrode assembly is further improved.

[0011] In some embodiments of the present application, the length of the single-side coating area in the winding direction of the electrode assembly is L0; the double-side coating area and the single-side coating area have a junction line, and the shortest distance from the junction line to the overlapping part in the winding direction of the electrode assembly is L1, and 5%≤L1 / L0≤50%.

[0012] In the technical solution, when L1 / L0 is greater than or equal to 5%, the overlapping part is spaced from the junction line of the double-sided coating area and the single-sided coating area, so that the overlapping part does not overlap the double-sided coating area, thereby enabling the overlapping part to provide greater support to the single-sided coating area than the double-sided coating area, so as to balance the difference in expansion force between the single-sided coating area and the double-sided coating area, reduce the risk of breaking of the current collector, and improve the safety of the cylindrical battery cell; when L1 / L0 is less than or equal to 50%, the distance between the overlapping part and the junction line of the double-sided coating area and the single-sided coating area is not too large, the support of the overlapping part to the region of the single-sided coating area close to the junction line is greater, the risk of breaking of the current collector in the junction region of the double-sided coating area and the single-sided coating area is reduced, and the safety of the cylindrical battery cell is improved; therefore, when 5%≤L1 / L0≤50%, the overlapping part can neither overlap the double-sided coating area nor have a distance that is too large from the junction line of the double-sided coating area and the single-sided coating area, and the support of the overlapping part to the single-sided coating area is better, the risk of breaking of the current collector in the junction region of the double-sided coating area and the single-sided coating area is reduced, and the safety of the cylindrical battery cell is improved.

[0013] In some embodiments of the present application, the double-sided coating area and the single-sided coating area have a junction line, and the shortest distance from the junction line to the overlapping part in the winding direction of the electrode assembly is L1, and 0.5mm≤L1≤60mm.

[0014] In the technical solution, when L1 is greater than or equal to 0.5mm, the overlapping part is spaced from the junction line of the double-sided coating area and the single-sided coating area, so that the overlapping part does not overlap the double-sided coating area, thereby enabling the overlapping part to provide greater support to the single-sided coating area than the double-sided coating area, so as to balance the difference in expansion force between the single-sided coating area and the double-sided coating area, reduce the risk of breaking of the current collector, and improve the safety of the cylindrical battery cell; when L1 is less than or equal to 60mm, the distance between the overlapping part and the junction line of the double-sided coating area and the single-sided coating area is not too large, the support of the overlapping part to the region of the single-sided coating area close to the junction line is greater, the risk of breaking of the current collector in the junction region of the double-sided coating area and the single-sided coating area is reduced, and the safety of the cylindrical battery cell is improved; therefore, when 0.5mm≤L1≤60mm, the overlapping part can neither overlap the double-sided coating area nor have a distance that is too large from the junction line of the double-sided coating area and the single-sided coating area, and the support of the overlapping part to the single-sided coating area is better, the risk of breaking of the current collector in the junction region of the double-sided coating area and the single-sided coating area is reduced, and the safety of the cylindrical battery cell is improved.

[0015] In some embodiments of the present application, 1mm≤L1≤30mm.

[0016] In the technical scheme, when L1 is greater than or equal to 1 mm, the overlapping part is spaced from the junction line of the double-sided coating area and the single-sided coating area, and the overlapping part does not overlap the double-sided coating area, so that the overlapping part can provide greater support to the single-sided coating area than the double-sided coating area, to balance the difference between the expansion forces of the single-sided coating area and the double-sided coating area, reduce the risk of breaking of the current collector, and further improve the safety of the cylindrical battery; when L1 is less than or equal to 30 mm, the distance between the overlapping part and the junction line of the double-sided coating area and the single-sided coating area is not too large, the support of the overlapping part to the region of the single-sided coating area close to the junction line is greater, the risk of breaking of the current collector in the junction region of the double-sided coating area and the single-sided coating area is reduced, and the safety of the cylindrical battery is further improved; therefore, when 1 mm≤L1≤30 mm, the overlapping part does not overlap the double-sided coating area, the distance between the overlapping part and the junction line of the double-sided coating area and the single-sided coating area is not too large, the support of the overlapping part to the single-sided coating area is better, the risk of breaking of the current collector in the junction region of the double-sided coating area and the single-sided coating area is reduced, and the safety of the cylindrical battery is further improved.

[0017] In some embodiments of the present application, the width of the first electrode tab in the direction of the winding axis of the electrode assembly is W2, and the width of the adhesive paper is W3, and 0.8≤W3 / W2≤1.1.

[0018] In the technical scheme, when W3 / W2 is greater than or equal to 0.8, the adhesive paper covers a larger area of the first electrode tab, which can reduce the risk of short circuit of the first electrode tab contacting external components and improve the safety of the cylindrical battery; when W3 / W2 is less than or equal to 1.1, the width of the adhesive paper that exceeds the first electrode tab or the part of the first electrode tab is small in the direction of the winding axis of the electrode assembly, which can reduce the problem that the adhesive paper is pressed between the first electrode tab and the current collector plate during welding of the first electrode tab and the current collector plate, causing a large internal resistance of the cylindrical battery, and is conducive to improving the rate performance of the cylindrical battery; therefore, when 0.8≤W3 / W2≤1.1, the risk of short circuit of the first electrode tab contacting external components can be reduced, the safety of the cylindrical battery can be improved, and the problem that the adhesive paper is pressed between the first electrode tab and the current collector plate during welding of the first electrode tab and the current collector plate, causing a large internal resistance of the cylindrical battery, can be reduced, which is conducive to improving the rate performance of the cylindrical battery.

[0019] In some embodiments of the present application, the first electrode tab includes a first current collector and a first active material layer, and the first active material layer is arranged on both sides of the first current collector along the thickness direction of the first current collector in the double-sided coating area; in the single-sided coating area, the first active material layer is arranged on the side of the single-sided coating area facing the second electrode tab, and the side of the single-sided coating area away from the second electrode tab is not provided with the first active material layer. The thickness of the single-layer first active material layer is H1, the thickness of the adhesive paper is H2, and 0.5≤H2 / H1≤0.9.

[0020] In the above technical solution, when H2 / H1 is greater than or equal to 0.5, H2 is not too small, the adhesive force of the adhesive paper on the electrode assembly is relatively large, the risk of metal ion precipitation caused by the misalignment of the first electrode tab and the second electrode tab in the winding axis direction of the electrode assembly is reduced, and the safety of the battery cell is improved; and / or, H1 is not too large, the first current collector can better support the first active material layer, and the risk of deformation of the first electrode tab is reduced; when H2 / H1 is less than or equal to 0.9, H2 is not too large, the space occupied by the adhesive paper is relatively small, the volume of the electrode assembly can be reduced, the electrode assembly can be easily loaded into the shell of the cylindrical battery cell, and the shell loading rate of the electrode assembly is improved; and / or, H1 is not too small, the volume of the first active material layer is not too small, and the energy density of the cylindrical battery cell is improved; therefore, when 0.5≤H2 / H1≤0.9, the cylindrical battery cell has high safety, manufacturing rate and energy density.

[0021] In some embodiments of the present application, the electrode assembly includes a negative electrode tab, the negative electrode tab includes a negative electrode current collector and a negative electrode active material layer, the negative electrode active material layer is arranged on at least one side of the negative electrode current collector along the thickness direction of the negative electrode current collector, the negative electrode active material layer includes a silicon-based material, the expansion coefficient of the negative electrode tab is k, the width of the overlapping part is W1 along the winding direction of the electrode assembly, and 0.1≤k≤0.5, 1mm≤W1≤8mm; or, 0.5

[0022] In the above technical solution, when 0.1≤k≤0.5, the expansion coefficient of the negative electrode tab is relatively small, the expansion amount of the negative electrode tab during the cycle process of the electrode assembly is relatively small, corresponding to 1mm≤W1≤8mm, the overlapping part occupies a relatively small space while providing sufficient supporting force to the single-sided coating area, the volume of the electrode assembly can be reduced, the electrode assembly can be easily loaded into the shell of the cylindrical battery cell, and the shell loading rate of the electrode assembly is improved; when 0.5

[0023] In some embodiments of the present application, the first electrode tab is a negative electrode tab, and the second electrode tab is a positive electrode tab.

[0024] In the above technical solution, since the negative active material of the negative electrode tab has a larger expansion amount than the positive active material of the positive electrode tab, by causing the projection of the single-side coating area on the adhesive paper to overlap with the overlap portion and the projection of the double-side coating area on the adhesive paper not to overlap with the overlap portion from the winding center of the electrode assembly outward, the overlap portion can better balance the difference in expansion force between the single-side coating area and the double-side coating area of the negative electrode tab, thereby reducing the problem of stress concentration at the junction of the single-side coating area and the double-side coating area, reducing the risk of current collector fracture, and improving the safety of the cylindrical battery cell.

[0025] In a second aspect, the present application provides a power utilization device, comprising the cylindrical battery cell as described above, and the cylindrical battery cell is used to provide electric energy. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained from these drawings.

[0027] Figure 1 A cross-sectional view of the cylindrical battery cell provided for some embodiments of the present application; Figure 2 A structure schematic diagram of a partial structure of the cylindrical battery cell from one perspective provided for some embodiments of the present application; Figure 3 A perspective view of the partial structure of the cylindrical battery cell from another perspective provided for some embodiments of the present application; Figure 4 A structure schematic diagram of the first electrode tab of the battery cell after being unfolded provided for some embodiments of the present application.

[0028] Figure legend: 10-cylindrical battery cell; 100-electrode assembly; 110-first electrode tab; 110a-double-side coating area; 110b-single-side coating area; 111-first current collector; 112-first active material layer; 120-second electrode tab; 130-separation film; 200-adhesive paper; 210-overlap portion; 300-outer shell; 310-pole; 410-first current collecting disc; 420-second current collecting disc; X-winding axis direction of the electrode assembly. DETAILED DESCRIPTION

[0029] In order to make the objects, technical solutions and advantages of the present application clearer, the technical solutions in the embodiments of the present application will be clearly described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art belong to the scope of protection of the present application.

[0030] Unless otherwise defined, all technical and scientific terms used in the present application have the same meanings as commonly understood by one of ordinary skill in the art to which the present application belongs; the terms used in the specification of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application; the terms "include" and "have" and any variations thereof in the specification and claims of the present application and the above description of drawings are intended to cover non-exclusive inclusion.

[0031] The terms "first", "second", etc. in the specification and claims of the present application or in the above description of drawings are used to distinguish different objects, rather than to describe a specific order or primary and secondary relationship.

[0032] In the present application, referring to "embodiments" means that the specific features, structures or characteristics described in connection with the embodiments can be included in at least one embodiment of the present application. The phrase appears at various places in the specification does not necessarily all refer to the same embodiment, nor is it mutually exclusive or alternative to other embodiments.

[0033] In the embodiments of the present application, the same reference signs represent the same components, and for brevity, detailed description of the same components is omitted in different embodiments. It should be understood that the thickness, length, width and other dimensions of various components in the embodiments of the present application shown in the drawings, as well as the overall thickness, length, width and other dimensions of the integrated device, are only exemplary and should not constitute any limitation on the present application.

[0034] With the development of the new energy industry, batteries gradually develop towards high safety. The cylindrical battery cell has an electrode assembly with a winding structure, the electrode assembly includes first and second pole pieces with opposite polarities, the outermost circle of the first pole piece is located outside the outermost circle of the second pole piece, the outermost circle of the first pole piece generally includes a double-sided coating area and a single-sided coating area, and the end of the single-sided coating area away from the double-sided coating area is the winding end of the first pole piece. During the cyclic charging and discharging process of the electrode assembly, the first pole piece will expand, and because the single-sided coating area is coated with a first active material layer and the double-sided coating area is coated with two layers of first active material layers, the expansion amounts of the single-sided coating area and the double-sided coating area will be different, causing stress concentration in the junction area of the single-sided coating area and the double-sided coating area, and the current collector in the junction area is at risk of breaking, and after the current collector breaks, it may pierce the separator, causing short circuit or failure of the cylindrical battery cell, affecting the safety of the battery cell.

[0035] In order to improve the safety of the cylindrical battery, the cylindrical battery provided by the application includes an electrode assembly with a winding structure and a rubber paper, the electrode assembly includes first and second polar plates with opposite polarities, the outermost circle of the first polar plate is located outside the outermost circle of the second polar plate, the outermost circle of the first polar plate includes a double-coated area and a single-coated area, and the end of the single-coated area away from the double-coated area is the winding end of the first polar plate. The rubber paper is wound around the outer periphery of the electrode assembly, the rubber paper has a starting section and an ending section, the starting section and the ending section overlap and form an overlapping part, and the projection of the single-coated area on the rubber paper overlaps the overlapping part, and the projection of the double-coated area on the rubber paper does not overlap the overlapping part.

[0036] In the cylindrical battery with the above structure, by winding the rubber paper around the outer periphery of the electrode assembly, the rubber paper has a starting section and an ending section, the starting section and the ending section overlap and form an overlapping part, so that the rubber paper can provide a better binding effect to the electrode assembly, the electrode assembly can maintain a better winding state, the charging and discharging process of the cylindrical battery is more stable, and the safety of the cylindrical battery is higher.

[0037] Since the overlapping part of the rubber paper has a larger thickness than other parts, by making the projection of the single-coated area on the rubber paper overlap the overlapping part and the projection of the double-coated area on the rubber paper not overlap the overlapping part from the winding center of the electrode assembly outward, the overlapping part can provide a larger support force to the single-coated area than the double-coated area, thereby balancing the difference in expansion force between the single-coated area and the double-coated area, reducing the problem of stress concentration at the junction of the single-coated area and the double-coated area, reducing the risk of current collector fracture, and thereby improving the safety of the cylindrical battery.

[0038] The cylindrical battery provided by the embodiments of the application can be a secondary battery, for example, a lithium ion battery, a sodium ion battery, a magnesium ion battery, etc., and the embodiments of the application are not limited thereto.

[0039] The embodiments of the application provide a power consumption device using the cylindrical battery as a power supply, which can be, but is not limited to, a mobile phone, a tablet computer, a notebook computer, an electric toy, an electric tool, an electric vehicle, an electric car, a ship, a spacecraft, etc.

[0040] Referring to Figure 1 and Figure 2 , Figure 1 a cross-sectional view of the cylindrical battery provided by some embodiments of the application; Figure 2 a structural schematic diagram of the cylindrical battery from one perspective provided by some embodiments of the application.

[0041] The embodiment of the present application provides a cylindrical battery cell 10, which comprises an electrode assembly 100 with a winding structure and a gum paper 200, the electrode assembly 100 comprises a first pole piece 110 and a second pole piece 120 with opposite polarities, the outermost circle of the first pole piece 110 is located outside the outermost circle of the second pole piece 120, the outermost circle of the first pole piece 110 comprises a double-coated area 110a and a single-coated area 110b, and the end of the single-coated area 110b away from the double-coated area 110a is the winding end of the first pole piece 110. The gum paper 200 is wound around the outer periphery of the electrode assembly 100, the gum paper 200 has a starting section and an ending section, the starting section and the ending section overlap and form an overlapping part 210, from the winding center of the electrode assembly 100 to the outside, the projection of the single-coated area 110b on the gum paper 200 overlaps with the overlapping part 210, and the projection of the double-coated area 110a on the gum paper 200 does not overlap with the overlapping part 210.

[0042] The first pole piece 110 comprises a first current collector 111 and a first active material layer 112, in the double-coated area 110a, the first current collector 111 is provided with the first active material layer 112 on both sides along the thickness direction of the first current collector 111; in the single-coated area 110b, the first current collector 111 is provided with the first active material layer 112 on one side along the thickness direction of the first current collector 111, and is not provided with the first active material layer 112 on the other side.

[0043] The starting section and the ending section of the gum paper 200 overlap and form the overlapping part 210, that is, the gum paper 200 is wound around the outer periphery of the electrode assembly 100 more than one whole circle and forms the overlapping.

[0044] By winding the gum paper 200 around the outer periphery of the electrode assembly 100, the gum paper 200 has the starting section and the ending section, the starting section and the ending section overlap and form the overlapping part 210, so that the gum paper 200 can provide better binding effect to the electrode assembly 100, the electrode assembly 100 can maintain a better winding state, so that the charging and discharging process of the cylindrical battery cell 10 is more stable, and the safety of the cylindrical battery cell 10 is higher.

[0045] Due to the expansion and shrinkage of the active material layer during the charging and discharging of the battery cell, the expansion amounts of the single-coated area 110b and the double-coated area 110a are different, which causes the risk of fracture of the current collector at the junction area of the single-coated area 110b and the double-coated area 110a. Since the overlapping portion 210 of the adhesive paper 200 has a greater thickness than other portions, by making the projection of the single-coated area 110b on the adhesive paper 200 overlap the overlapping portion 210 and the projection of the double-coated area 110a on the adhesive paper 200 not overlap the overlapping portion 210 from the center of the winding of the electrode assembly 100 outward, the overlapping portion 210 can provide greater support to the single-coated area 110b than to the double-coated area 110a, thereby balancing the difference in expansion force between the single-coated area 110b and the double-coated area 110a, reducing the problem of stress concentration at the junction of the single-coated area 110b and the double-coated area 110a, reducing the risk of fracture of the current collector, and thus improving the safety of the cylindrical battery cell 10.

[0046] Measurement method of the overlapping portion 210: after the cylindrical battery cell 10 is fully discharged, the shell 300 is disassembled to obtain the electrode assembly 100 wound with the adhesive paper 200; a soft ruler with a precision of 0.1 mm is used to measure the width of the overlapping portion 210 of the adhesive paper 200 along the winding direction of the electrode assembly 100; the widths of the overlapping portions 210 of 10 cylindrical battery cells 10 are measured and averaged.

[0047] For reference Figure 3 , Figure 3 Another perspective view of the cylindrical battery cell provided for some embodiments of the present application.

[0048] In some embodiments, along the winding direction of the electrode assembly 100, the width of the overlapping portion 210 is W1, and 1 mm≤W1≤15 mm. For example, W1 can be 1 mm, 3 mm, 5 mm, 7 mm, 9 mm, 10 mm, 12 mm, or 15 mm, etc.

[0049] When W1 is greater than or equal to 1 mm, the width of the overlapping portion 210 is not too small, the supporting force of the overlapping portion 210 on the single-coated area 110b is greater, the difference between the expansion forces of the single-coated area 110b and the double-coated area 110a is further reduced, the problem of stress concentration at the junction of the single-coated area 110b and the double-coated area 110a is further reduced, the risk of breaking of the current collector is reduced, and thus the safety of the cylindrical battery cell 10 is further improved; and the adhesive force of the adhesive paper 200 on the electrode assembly 100 is greater, the risk of metal ion precipitation caused by the misalignment of the first and second electrode tabs 110 and 120 in the winding axis direction X of the electrode assembly is reduced, and the safety of the battery cell is improved; when W1 is less than or equal to 15 mm, the width of the overlapping portion 210 is not too large, the space occupied by the overlapping portion 210 is small, the volume of the electrode assembly 100 can be reduced, the electrode assembly 100 can be easily loaded into the shell of the cylindrical battery cell 10, and the shell loading rate of the electrode assembly 100 is improved; therefore, when 1 mm≤W1≤15 mm, the difference between the expansion forces of the single-coated area 110b and the double-coated area 110a can be further reduced, the problem of stress concentration at the junction of the single-coated area 110b and the double-coated area 110a is further reduced, the risk of breaking of the current collector is reduced, and thus the safety of the cylindrical battery cell 10 is further improved, the adhesive force of the adhesive paper 200 on the electrode assembly 100 is greater, the risk of metal ion precipitation caused by the misalignment of the first and second electrode tabs 110 and 120 in the winding axis direction X of the electrode assembly is reduced, and the safety of the battery cell is improved, and the volume of the cylindrical battery cell 10 can be reduced, and thus the shell loading rate of the electrode assembly 100 is improved.

[0050] In some embodiments, 3 mm≤W1≤8 mm. For example, W1 can be 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, or 8 mm, etc.

[0051] When W1 is greater than or equal to 3 mm, the width of the overlapping portion 210 is further prevented from being too small, the supporting force of the overlapping portion 210 on the single-coated area 110b is greater, the difference between the expansion forces of the single-coated area 110b and the double-coated area 110a is further reduced, the problem of stress concentration at the junction of the single-coated area 110b and the double-coated area 110a is further reduced, the risk of breaking of the current collector is reduced, and thus the safety of the cylindrical battery cell 10 is further improved; and the adhesive tape 200 has a greater bonding force on the electrode assembly 100, the risk of metal ion precipitation caused by misalignment of the first electrode tab 110 and the second electrode tab 120 in the winding axis direction X of the electrode assembly is reduced, and thus the safety of the battery cell is further improved; when W1 is less than or equal to 8 mm, the width of the overlapping portion 210 is further prevented from being too large, the space occupied by the overlapping portion 210 is smaller, the volume of the electrode assembly 100 can be reduced, the electrode assembly 100 can be easily loaded into the shell of the cylindrical battery cell 10, and the shell loading rate of the electrode assembly 100 is improved. Therefore, when 3 mm≤W1≤8 mm, the difference between the expansion forces of the single-coated area 110b and the double-coated area 110a can be further reduced, the problem of stress concentration at the junction of the single-coated area 110b and the double-coated area 110a can be further reduced, the risk of breaking of the current collector can be reduced, and thus the safety of the cylindrical battery cell 10 can be further improved. In addition, the adhesive tape 200 has a greater bonding force on the electrode assembly 100, the risk of metal ion precipitation caused by misalignment of the first electrode tab 110 and the second electrode tab 120 in the winding axis direction X of the electrode assembly is reduced, and thus the safety of the battery cell is further improved. In addition, the volume of the cylindrical battery cell 10 can be further reduced, and thus the shell loading rate of the electrode assembly 100 can be further improved.

[0052] Referring to Figure 3 and Figure 4 , Figure 4 FIG. 1 is a structural schematic diagram of an electrode assembly according to some embodiments of the present application.

[0053] In some embodiments, the length of the single-coated area 110b in the winding direction of the electrode assembly 100 is L0; the single-coated area 110b and the double-coated area 110a have a junction line, and the shortest distance from the junction line to the overlapping portion 210 in the winding direction of the electrode assembly 100 is L1, and 5%≤L1 / L0≤50%. For example, L1 / L0 can be 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, or 50%, etc.

[0054] The shortest distance from the junction line to the overlapping portion 210 is the distance from the junction line to the edge of the overlapping portion 210 close to the junction line.

[0055] When L1 / L0 is greater than or equal to 5%, the overlapping portion 210 is spaced from the junction line of the double-coated area 110a and the single-coated area 110b, so that the overlapping portion 210 does not overlap the double-coated area 110a, thereby enabling the overlapping portion 210 to provide greater support to the single-coated area 110b than to the double-coated area 110a, to balance the difference in expansion force between the single-coated area 110b and the double-coated area 110a, reduce the risk of breaking of the current collector, and improve the safety of the cylindrical battery cell 10. When L1 / L0 is less than or equal to 50%, the distance between the overlapping portion 210 and the junction line of the double-coated area 110a and the single-coated area 110b is not too large, and the support of the overlapping portion 210 to the region of the single-coated area 110b near the junction line is greater, thereby reducing the risk of breaking of the current collector in the junction region of the double-coated area 110a and the single-coated area 110b, and improving the safety of the cylindrical battery cell 10. Therefore, when 5%≤L1 / L0≤50%, the overlapping portion 210 does not overlap the double-coated area 110a, and the distance between the overlapping portion 210 and the junction line of the double-coated area 110a and the single-coated area 110b is not too large, both of which enable the overlapping portion 210 to better support the single-coated area 110b, reduce the risk of breaking of the current collector in the junction region of the double-coated area 110a and the single-coated area 110b, and improve the safety of the cylindrical battery cell 10.

[0056] In some embodiments, the double-coated area 110a and the single-coated area 110b have a junction line, and the shortest distance from the junction line to the overlapping portion 210 in the winding direction of the electrode assembly 100 is L1, 0.5mm≤L1≤60mm. For example, L1 can be 0.5mm, 0.8mm, 1mm, 3mm, 5mm, 10mm, 20mm, 30mm, 40mm, 50mm, or 60mm, etc.

[0057] When L1 is greater than or equal to 0.5 mm, the overlapping portion 210 is spaced from the junction line of the double-coated area 110a and the single-coated area 110b, so that the overlapping portion 210 does not overlap the double-coated area 110a, thereby enabling the overlapping portion 210 to provide greater support to the single-coated area 110b than to the double-coated area 110a, to balance the difference in expansion force between the single-coated area 110b and the double-coated area 110a, reduce the risk of current collector fracture, and improve the safety of the cylindrical battery cell 10. When L1 is less than or equal to 60 mm, the distance between the overlapping portion 210 and the junction line of the double-coated area 110a and the single-coated area 110b is not too large, and the support of the overlapping portion 210 to the area of the single-coated area 110b near the junction line is greater, thereby reducing the risk of current collector fracture in the junction area of the double-coated area 110a and the single-coated area 110b and improving the safety of the cylindrical battery cell 10. Therefore, when 0.5 mm≤L1≤60 mm, the overlapping portion 210 does not overlap the double-coated area 110a, and the distance between the overlapping portion 210 and the junction line of the double-coated area 110a and the single-coated area 110b is not too large, both of which enable the overlapping portion 210 to better support the single-coated area 110b, reduce the risk of current collector fracture in the junction area of the double-coated area 110a and the single-coated area 110b, and improve the safety of the cylindrical battery cell 10.

[0058] In some embodiments, 1 mm≤L1≤30 mm. For example, L1 can be 1 mm, 2 mm, 6 mm, 8 mm, 10 mm, 15 mm, 17 mm, 20 mm, 25 mm, or 30 mm, etc.

[0059] When L1 is greater than or equal to 1 mm, the overlapping portion 210 is spaced from the junction line of the double-coated area 110a and the single-coated area 110b, further ensuring that the overlapping portion 210 does not overlap the double-coated area 110a, so that the overlapping portion 210 can provide greater support to the single-coated area 110b than to the double-coated area 110a, to balance the difference in expansion force between the single-coated area 110b and the double-coated area 110a, reduce the risk of breaking of the current collector, and further improve the safety of the cylindrical battery cell 10. When L1 is less than or equal to 30 mm, the distance between the overlapping portion 210 and the junction line of the double-coated area 110a and the single-coated area 110b is not too large, and the support of the overlapping portion 210 to the area of the single-coated area 110b near the junction line is greater, reducing the risk of breaking of the current collector in the junction area of the double-coated area 110a and the single-coated area 110b, and further improving the safety of the cylindrical battery cell 10. Therefore, when 1 mm≤L1≤30 mm, the overlapping portion 210 can further ensure that it does not overlap the double-coated area 110a, and the distance between the overlapping portion 210 and the junction line of the double-coated area 110a and the single-coated area 110b is not too large, both of which can further improve the support effect of the overlapping portion 210 to the single-coated area 110b, reduce the risk of breaking of the current collector in the junction area of the double-coated area 110a and the single-coated area 110b, and further improve the safety of the cylindrical battery cell 10.

[0060] Referring to Figure 3 In some embodiments, along the winding axis direction X of the electrode assembly, the width of the first electrode tab 110 is W2, and the width of the adhesive paper 200 is W3, and 0.8≤W3 / W2≤1.1. For example, W3 / W2 can be 0.8, 0.85, 0.87, 0.9, 0.92, 0.95, 0.98, 1, or 1.1, etc.

[0061] When W3 / W2 is greater than or equal to 0.8, the coverage area of the adhesive paper 200 on the first tab 110 is large, which can reduce the risk of short circuit of the first tab 110 contacting external components, and improve the safety of the cylindrical battery cell 10; when W3 / W2 is less than or equal to 1.1, along the winding axis direction X of the electrode assembly, the width of the portion of the adhesive paper 200 that exceeds the first tab 110 or the portion of the first tab 110 that exceeds the adhesive paper 200 is small, which can reduce the problem that the adhesive paper 200 is pressed between the first tab 110 and the current collector plate when the first tab 110 is welded with the current collector plate, causing the internal resistance of the cylindrical battery cell 10 to be large, and is conducive to improving the rate performance of the cylindrical battery cell 10; therefore, when 0.8≤W3 / W2≤1.1, the risk of short circuit of the first tab 110 contacting external components can be reduced, the safety of the cylindrical battery cell 10 can be improved, and the problem that the adhesive paper 200 is pressed between the first tab 110 and the current collector plate when the first tab 110 is welded with the current collector plate, causing the internal resistance of the cylindrical battery cell 10 to be large, can be reduced, which is conducive to improving the rate performance of the cylindrical battery cell 10.

[0062] In some embodiments, the first tab 110 includes a first current collector 111 and a first active material layer 112, and the first current collector 111 is provided with the first active material layer 112 on both sides along the thickness direction thereof in the double-sided coating area 110a; in the single-sided coating area 110b, the first active material layer 112 is provided on the side of the single-sided coating area 110b facing the second tab 120, and the side of the single-sided coating area 110b away from the second tab 120 is not provided with the first active material layer 112. The thickness of the single-layer first active material layer 112 is H1, and the thickness of the adhesive paper 200 is H2, and 0.5≤H2 / H1≤0.9. For example, H2 / H1 can be 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85 or 0.9, etc.

[0063] When H2 / H1 is greater than or equal to 0.5, H2 will not be too small, the adhesion of the adhesive paper 200 to the electrode assembly 100 is large, which can reduce the risk of metal ion precipitation caused by the misalignment of the first tab 110 and the second tab 120 in the winding axis direction X of the electrode assembly, and improve the safety of the battery cell; and / or, H1 will not be too large, the first current collector 111 can better support the first active material layer 112, and reduce the risk of deformation of the first tab 110; when H2 / H1 is less than or equal to 0.9, H2 will not be too large, the space occupied by the adhesive paper 200 is small, which can reduce the volume of the electrode assembly 100, facilitate the electrode assembly 100 to be loaded into the shell of the cylindrical battery cell 10, and be conducive to improving the shell loading rate of the electrode assembly 100; and / or, H1 will not be too small, the volume of the first active material layer 112 will not be too small, which is conducive to improving the energy density of the cylindrical battery cell 10; therefore, when 0.5≤H2 / H1≤0.9, the cylindrical battery cell 10 has high safety, manufacturing rate and energy density.

[0064] In some embodiments, the electrode assembly 100 includes a negative electrode tab including a negative current collector and a negative active material layer disposed on at least one side of the negative current collector along the thickness direction thereof, the negative active material layer including a silicon-based material, the negative electrode tab having a coefficient of expansion k, along the winding direction of the electrode assembly 100, the overlap portion 210 having a width W1, 0.1≤k≤0.5, 1mm≤W1≤8mm. For example, k can be 0.1, 0.2, 0.3, 0.4, or 0.5, etc., and W1 can be 1mm, 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, or 8mm, etc.

[0065] When 0.1≤k≤0.5, the coefficient of expansion of the negative electrode tab is small, and the amount of expansion of the negative electrode tab during the cycling of the electrode assembly 100 is small, corresponding to 1mm≤W1≤8mm, the overlap portion 210 occupies a small space while providing sufficient support force to the single-sided coating area 110b, which can reduce the volume of the electrode assembly 100, facilitate the loading of the electrode assembly 100 into the shell of the cylindrical battery cell 10, and be beneficial to improve the shell-entering rate of the electrode assembly 100; when 0.5

[0066] In some embodiments, 0.5

[0067] The test method of the expansion coefficient k of the negative electrode sheet includes: charging one cylindrical battery 10 to 4.2V at 2C in a 25℃ constant temperature box, charging to 0.05C at 4.2V, and standing for 5 minutes (i.e. full charging); charging another cylindrical battery 10 of the same batch to 4.2V at 2C in a 25℃ constant temperature box, charging to 0.05C at 4.2V, standing for 5 minutes, and then discharging to 2.5V at 6C (i.e. full discharge); disassembling the two cylindrical batteries 10 respectively, and immersing the negative electrode sheet in dimethyl carbonate solvent for 10 minutes, measuring the thickness of the negative electrode sheet with a micrometer, and taking the average value after measuring 15 points; measuring the thickness of the negative electrode sheet of the full charging cylindrical battery 10 as T1, measuring the thickness of the negative electrode sheet of the full discharge cylindrical battery 10 as T2, and the expansion coefficient k of the negative electrode sheet = T2 / T1.

[0068] Referring to Figure 1 and Figure 2 In some embodiments, the first electrode sheet 110 is a negative electrode sheet, and the second electrode sheet 120 is a positive electrode sheet.

[0069] Since the expansion amount of the negative active material of the negative electrode sheet is larger than that of the positive active material of the positive electrode sheet, by making the projection of the single-side coated area 110b on the adhesive paper 200 overlap with the overlapping part 210 and the projection of the double-side coated area 110a on the adhesive paper 200 not overlap with the overlapping part 210 from the winding center of the electrode assembly 100 outward, the overlapping part 210 can better balance the difference in expansion force between the single-side coated area 110b and the double-side coated area 110a of the negative electrode sheet, thereby reducing the problem of stress concentration at the junction of the single-side coated area 110b and the double-side coated area 110a, reducing the risk of current collector fracture, and improving the safety of the cylindrical battery 10.

[0070] In some embodiments, the electrode assembly 100 further includes a separator film 130 disposed between the positive electrode sheet and the negative electrode sheet for insulating and separating the positive electrode sheet and the negative electrode sheet to reduce the risk of short circuit of the cylindrical battery 10.

[0071] The cylindrical battery cell 10 also includes a shell 300 and an electrolyte (not shown in the figure), and the electrode assembly 100 and the electrolyte are contained in the shell 300. The cylindrical battery cell 10 mainly works by moving metal ions between the positive electrode tab and the negative electrode tab. The positive electrode tab includes a positive electrode current collector and a positive electrode active material layer, the positive electrode active material layer is coated on the surface of the positive electrode current collector, and the part of the positive electrode current collector without the positive electrode active material layer serves as a positive electrode tab to realize the input or output of electric energy of the positive electrode tab through the positive electrode tab. Taking a lithium ion battery as an example, the material of the positive electrode current collector can be aluminum, and the positive electrode active material can be lithium cobaltate, lithium iron phosphate, ternary materials (such as lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, etc.) or lithium manganese acid, etc. The negative electrode tab includes a negative electrode current collector and a negative electrode active material layer, the negative electrode active material layer is coated on the surface of the negative electrode current collector, and the part of the negative electrode current collector without the negative electrode active material layer serves as a negative electrode tab to realize the input or output of electric energy of the negative electrode tab through the negative electrode tab. The material of the negative electrode current collector can be copper, and the negative electrode active material can be a carbon material or a silicon material, etc. The material of the separator 130 can be polypropylene (PP) or polyethylene (PE), etc. The electrolyte can include an organic solvent, an electrolyte lithium salt, etc.

[0072] In some other embodiments, the first electrode tab 110 can be a positive electrode tab, and the second electrode tab 120 can be a negative electrode tab.

[0073] Referring to Figure 1 In some embodiments, the cylindrical battery cell 10 also includes a first current collecting disc 410, and the shell 300 is provided with a pole 310 which is insulatedly connected with the shell 300. The first current collecting disc 410 can be connected with the pole 310, so that the positive electrode tab is electrically connected with the pole 310 through the first current collecting disc 410.

[0074] In some embodiments, the cylindrical battery cell 10 also includes a second current collecting disc 420, and the negative electrode tab is electrically connected with the shell 300 through the second current collecting disc 420.

[0075] The embodiments of the present application provide a kind of electric equipment, including the cylindrical battery cell 10 provided in any one of the above embodiments, and the cylindrical battery cell 10 is used to provide electric energy.

[0076] Method for manufacturing cylindrical battery cell: Embodiment 1 <Preparation of positive electrode tab> The positive electrode active material lithium nickel cobalt manganese acid (LiNi 0.91 Co 0.045 Mn 0.045The positive electrode active material LiFePO4, the binder polyvinylidene fluoride (PVDF), and conductive carbon black were dispersed in N-methyl pyrrolidone (NMP) solvent at a mass ratio of 97.1:1.6:1.3, mixed well under stirring, to obtain a positive electrode slurry with a solid content of 72 wt%. The positive electrode slurry was uniformly coated on one surface of a positive electrode current collector aluminum foil with a thickness of 13 μm, and dried at 105 °C to obtain a positive electrode tab with a single first positive electrode active material layer.

[0077] The specification of the positive electrode tab was 66.5 mm x 1688 mm, and the coating weight of the first positive electrode active material layer and the second positive electrode active material layer was 196.5 mg / 1540.25 mm 2 The specification of the first positive electrode active material layer was 60 mm x 1688 mm, the specification of the second positive electrode active material layer was the same as that of the first positive electrode active material layer, and the width of the empty foil area of the positive electrode tab was 4.5 mm.

[0078] <Preparation of a negative electrode tab> The negative electrode active material artificial graphite, the negative electrode active material silicon-carbon material SiC, carboxymethyl cellulose sodium (CMC-Na), and styrene-butadiene rubber (SBR) were mixed at a mass ratio of 82.45:14.55:1.7:1.3, and then deionized water was added as a solvent, and the mixture was stirred and mixed uniformly to obtain a negative electrode slurry with a solid content of 50 wt%. The negative electrode slurry was uniformly coated on one surface of a negative electrode current collector copper foil with a thickness of 8 μm, and dried at 105 °C to obtain a negative electrode tab with a single first negative electrode active material layer. Then, the above steps were repeated on the other surface of the negative electrode current collector copper foil to obtain a negative electrode tab coated with a first negative electrode active material layer and a second negative electrode active material layer.

[0079] The specification of the negative electrode tab was 67.45 mm x 1730 mm, and the coating weight of the first negative electrode active material layer and the second negative electrode active material layer was 78 mg / 1540.25 mm 2 The specification of the first negative electrode active material layer was 62 mm x 1730 mm, the specification of the second negative electrode active material layer was 62 mm x 1666 mm, the sum of the thicknesses of the first negative electrode active material layer and the negative electrode current collector was 40 μm, and the width of the empty foil area of the negative electrode tab was 5.45 mm.

[0080] <Separator film> A polyethylene (PE) film with a thickness of 11 μm was used as the separator film.

[0081] <Preparation of an electrolyte> In a glove box filled with dry argon, organic solvent ethylene carbonate (EC), methyl ethyl carbonate (EMC), diethyl carbonate (DEC) were mixed in a mass ratio of 30:50:20 to obtain a base solvent, then lithium salt lithium hexafluorophosphate (LiPF6) was added to the above-mentioned base solvent, and the mixture was uniformly mixed to obtain an electrolyte. The mass percentage of LiPF6 in the electrolyte is 12.5%, and the balance is the base solvent.

[0082] <Preparation of cylindrical battery> The above-prepared separator, negative electrode sheet, separator, and positive electrode sheet were sequentially stacked in order, with the separator between the negative electrode sheet and the positive electrode sheet, to form an electrode assembly by winding. The outermost circle of the negative electrode sheet is located outside the outermost circle of the positive electrode sheet, and the outermost circle of the negative electrode sheet includes a double-coated area and a single-coated area, and the first negative active material layer faces away from the center of the electrode assembly formed by pre-winding. The length of the single-coated area L0 is 64 mm along the winding direction of the electrode assembly. Then, a length of 66 mm, a width of 59 mm, and a width of 59 mm were used to wrap the electrode assembly, so that the starting segment and the ending segment of the adhesive tape overlap to form an overlapping part with a width W1 of 2 mm, and the shortest distance L1 between the junction line of the double-coated area and the single-coated area and the overlapping part is 2 mm along the winding direction of the electrode assembly.

[0083] After the electrode assembly was put into the shell, the electrolyte was injected, and the electrode assembly was sealed and placed at high temperature, and then the formation was carried out, and the cylindrical battery was obtained. The upper limit of the formation is 4.2V, and the formation temperature is 45℃.

[0084] The preparation methods of Examples 2 to 8 and Comparative Examples 1 to 4 are basically the same as those of Example 1, except for the parameters in Table 1. The preparation method of Comparative Example 5 is basically the same as that of Example 1, except that the overlapping part of Comparative Example 5 overlaps with the projection part of the double-coated area of the outermost circle of the negative electrode sheet. The batteries of Examples 1 to 8 and Comparative Examples 1 to 5 were subjected to cycle tests, and the test results are shown in Table 1.

[0085] Table 1

[0086] Method for judging whether the outermost circle of the negative electrode sheet is broken: (1) The cylindrical battery was charged at an ambient temperature of 25±2℃, and then charged at a constant current of 3C to 4.2V, and then charged at a constant voltage of 4.2V to 0.05C and stood for 5min.

[0087] (2) After the cylindrical battery was fully charged, the shell of the cylindrical battery was removed, and the outer periphery of the electrode assembly of the winding structure was observed along the circumferential direction of the electrode assembly.

[0088] (3) If there is a crack with a length greater than or equal to 0.1 mm and a width greater than or equal to 0.1 mm in the outermost circle of the negative electrode tab (which can be observed by a Leica microscope DM500 at 200x magnification), it is determined that the outermost circle of the negative electrode tab is broken; otherwise, it is determined that the outermost circle of the negative electrode tab is not broken.

[0089] Impact test method of cylindrical battery cell: (1) The cylindrical battery cell is charged at 3C constant current to 4.2V at an ambient temperature of 25±2℃, and then charged at 4.2V constant voltage to 0.05C, at which time the full charge state is reached.

[0090] (2) The cylindrical battery cell in the full charge state is placed on the test table so that the axis of the cylindrical battery cell is parallel to the test table surface; a round rod with a diameter of 15.8 mm and a length of 6 cm is placed in the center of the cylindrical battery cell, and the axis of the round rod is perpendicular to the table surface.

[0091] (3) A 9.1 kg weight is allowed to fall freely from a height of 610 mm from the test table, falling on the intersection of the round rod and the cylindrical battery cell.

[0092] (4) If the cylindrical battery cell does not catch fire or explode, it is determined that the impact test of the cylindrical battery cell is passed. 20 cylindrical battery cells are tested for each comparative example or embodiment, and the impact test pass rate of the cylindrical battery cell = the number of cylindrical battery cells that pass the test / 20.

[0093] According to Table 1, the following conclusions are drawn: (1) Referring to Examples 1 to 9 and Comparative Example 5, by allowing the projection of the single-sided coating area on the adhesive paper to overlap with the overlap portion and the projection of the double-sided coating area on the adhesive paper to not overlap with the overlap portion from the winding center of the electrode assembly outward, the overlap portion can provide greater support to the single-sided coating area than to the double-sided coating area, thereby balancing the difference in expansion force between the single-sided coating area and the double-sided coating area, reducing the problem of stress concentration at the junction of the single-sided coating area and the double-sided coating area, reducing the risk of current collector breakage, and improving the impact test pass rate of the battery cell, thereby improving the safety of the cylindrical battery cell. In Comparative Example 5, the overlap portion partially overlaps with the projection of the double-sided coating area, the difference in expansion force between the single-sided coating area and the double-sided coating area is large, and the support of the overlap portion to the single-sided coating area and the double-sided coating area is close. Therefore, there is a problem of stress concentration at the junction of the single-sided coating area and the double-sided coating area, the risk of current collector breakage is high, and the impact test pass rate of the battery cell is low.

[0094] (2) According to the embodiments 1-4 and comparative examples 1-2, when L1 / L0 is less than 5%, the overlap part is prone to overlap with the double-coated area due to the manufacturing process precision of the battery cell, the support force of the overlap part on the single-coated area and the double-coated area is close, and thus the stress concentration problem still exists at the junction of the single-coated area and the double-coated area, the risk of the current collector breaking is high, and the passing rate of the impact test of the battery cell is low. When L1 / L0 is greater than 50%, the distance between the overlap part and the junction line of the double-coated area and the single-coated area is too large, the support force of the overlap part on the area of the single-coated area close to the junction line is small, the risk of the current collector breaking at the junction area of the double-coated area and the single-coated area is high, and the passing rate of the impact test of the battery cell is low. When 5%≤L1 / L0≤50%, the overlap part will not overlap with the double-coated area, the distance between the overlap part and the junction line of the double-coated area and the single-coated area will not be too large, the support effect of the overlap part on the single-coated area is better, the risk of the current collector breaking at the junction area of the double-coated area and the single-coated area is reduced, the passing rate of the impact test of the battery cell is high, and the safety of the cylindrical battery cell is improved.

[0095] (3) According to the embodiments 5-9 and comparative examples 3-4, when W1 is less than 1 mm, the width of the overlap part is too small, the support force of the overlap part on the single-coated area is small, the difference between the expansion forces of the single-coated area and the double-coated area is large, the stress concentration problem still exists at the junction of the single-coated area and the double-coated area, the risk of the current collector breaking is high, and the passing rate of the impact test of the battery cell is low. When W1 is greater than 15 mm, the width of the overlap part is too large, the space occupied by the overlap part is too large, the electrode assembly is not convenient to put into the shell of the cylindrical battery cell, and the overlap part is prone to overlap with the double-coated area, the support force of the overlap part on the single-coated area and the double-coated area is close, and thus the stress concentration problem still exists at the junction of the single-coated area and the double-coated area, the risk of the current collector breaking is high, and the passing rate of the impact test of the battery cell is low. When 1 mm≤W1≤15 mm, the difference between the expansion forces of the single-coated area and the double-coated area can be reduced, the stress concentration problem at the junction of the single-coated area and the double-coated area can be reduced, the risk of the current collector breaking can be reduced, and the passing rate of the impact test of the battery cell can be improved; when 3 mm≤W1≤8 mm, the difference between the expansion forces of the single-coated area and the double-coated area can be further reduced, the risk of the current collector breaking can be reduced, the passing rate of the impact test of the battery cell can be improved, and the space occupied by the overlap part can be reduced, thereby reducing the volume of the cylindrical battery cell and improving the shell-entering rate of the electrode assembly.

[0096] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0097] The above merely provides preferred embodiments of the present application, and is not used to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the principles and technical scope of the present application shall fall into the scope of the present application.

Claims

1. A cylindrical cell, characterized by, The cylindrical battery cell comprises: An electrode assembly with a winding structure, the electrode assembly comprising first and second polar tabs with opposite polarities, an outermost turn of the first polar tab being located outward of an outermost turn of the second polar tab, the outermost turn of the first polar tab comprising a double-coated region and a single-coated region, the single-coated region being distal to one end of the double-coated region and being a winding end of the first polar tab; An adhesive tape wound around an outer periphery of the electrode assembly, the adhesive tape having a starting section and an ending section, the starting section and the ending section being overlapped and forming an overlap region, from a winding center of the electrode assembly outward, a projection of the single-coated region on the adhesive tape overlaps the overlap region, and a projection of the double-coated region on the adhesive tape does not overlap the overlap region.

2. The cylindrical cell of claim 1, wherein, In a winding direction of the electrode assembly, a width of the overlap region is W1, and 1mm≤W1≤15mm.

3. The cylindrical cell of claim 2, wherein, 3mm≤W1≤8mm.

4. The cylindrical cell of claim 1, wherein, In the winding direction of the electrode assembly, a length of the single-coated region is L0; The double-coated region and the single-coated region have an interface line, and a shortest distance from the interface line to the overlap region in the winding direction of the electrode assembly is L1, and 5%≤L1 / L0≤50%.

5. The cylindrical cell of claim 1, wherein, The double-coated region and the single-coated region have an interface line, and a shortest distance from the interface line to the overlap region in the winding direction of the electrode assembly is L1, and 0.5mm≤L1≤60mm.

6. The cylindrical cell of claim 5, wherein, 1mm≤L1≤30mm.

7. The cylindrical cell of claim 1, wherein, In a winding axis direction of the electrode assembly, a width of the first polar tab is W2, and a width of the adhesive tape is W3, and 0.8≤W3 / W2≤1.

1.

8. The cylindrical cell of claim 1, wherein, The first polar tab comprises a first current collector and a first active material layer, in the double-coated region, the first current collector has the first active material layer disposed on both sides of the first current collector in a thickness direction of the first current collector; in the single-coated region, the first active material layer is disposed on a side of the single-coated region facing the second polar tab, and the first active material layer is not disposed on a side of the single-coated region facing away from the second polar tab; A thickness of a single layer of the first active material layer is H1, and a thickness of the adhesive tape is H2, and 0.5≤H2 / H1≤0.

9.

9. The cylindrical cell of claim 1, wherein, The electrode assembly comprises a negative polar tab, the negative polar tab comprising a negative current collector and a negative active material layer, the negative active material layer being disposed on at least one side of the negative current collector in a thickness direction of the negative current collector, the negative active material layer comprising a silicon-based material, a coefficient of expansion of the negative polar tab is k, in the winding direction of the electrode assembly, a width of the overlap region is W1, and 0.1≤k≤0.5, and 1mm≤W1≤8mm; Or, 0.5<k≤1.0, and 8mm<W1≤15mm.

10. The cylindrical cell of claim 1, wherein, The first polar tab is a negative polar tab, and the second polar tab is a positive polar tab.

11. An electrical device, characterized by The cylindrical battery cell as claimed in any one of claims 1-10 is used to provide electrical energy.

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