Battery cell and battery

Abstract

The utility model provides a battery cell and battery, the battery cell comprises a first pole piece, a second pole piece and a diaphragm located between the first pole piece and the second pole piece, the first pole piece, the diaphragm and the second pole piece are laminated and wound to form a roll core, the first pole piece comprises a first current collector, a first active layer and a first tab; the second pole piece comprises a second current collector and a second active layer arranged on the second current collector; the first pole piece comprises a winding head positioned on the inner ring of the winding core and a winding tail positioned on the outer ring of the winding core; the first current collector comprises a first empty foil area and a first coating area coated with a first active layer, and the first empty foil area is located at the winding head part and / or the winding tail part; the first insulating layer is arranged on the first empty foil area, the first tab groove is formed in the first insulating layer, and the first tab is arranged in the first tab groove, so that short circuit of the positive electrode and the negative electrode caused by exposure of the first empty foil area is avoided to a certain extent.

Description

Technical Field

[0001] The utility model relates to the technical field of batteries, and particularly relates to a battery cell and a battery. Background Art

[0002] Lithium-ion batteries are widely used in portable devices such as mobile phones and laptop computers, such as wound lithium-ion batteries.

[0003] The battery cell of a wound lithium-ion battery includes a positive electrode sheet, a negative electrode sheet and a separator. The positive electrode sheet, the separator and the negative electrode sheet are stacked and wound from the inside out to form a wound core. Among them, the positive electrode sheet includes a positive current collector and a positive active layer provided on the surface of the positive current collector, and the negative electrode sheet includes a negative current collector and a negative active layer provided on the surface of the negative current collector. In the wound battery cell of the related art, there will be some empty foils on the electrode sheets, which easily leads to short circuit between the positive and negative electrodes and affects the safety performance of the battery. Summary of the Utility Model

[0004] In view of this, the embodiments of the present utility model are committed to providing a battery cell and a battery to improve the problem of short circuit between the positive and negative electrodes to a certain extent and improve the safety performance of the battery.

[0005] In a first aspect, the present utility model provides a battery cell, which includes a first electrode sheet, a second electrode sheet and a separator located between the first electrode sheet and the second electrode sheet;

[0006] The first electrode sheet, the separator and the second electrode sheet are stacked and wound to form a wound core;

[0007] The first electrode sheet includes a first current collector, a first active layer and a first tab;

[0008] The second electrode sheet includes a second current collector and a second active layer provided on the second current collector;

[0009] The first electrode sheet includes a winding head located inside the inner circle of the wound core and a winding tail located outside the outer circle of the wound core;

[0010] The first current collector includes a first empty foil area and a first coated area coated with the first active layer, and the first empty foil area is located at the winding head and / or the winding tail of the first electrode sheet;

[0011] A first insulating layer is provided on the first empty foil area, and a first tab groove is provided on the first insulating layer, and the first tab is provided in the first tab groove.

[0012] The battery cell provided by the present utility model avoids the occurrence of short circuit between the positive and negative electrodes caused by the exposure of the first empty foil area to a certain extent by providing a first insulating layer on the first empty foil area of the first electrode tab; at the same time, a first tab groove is provided on the first insulating layer, and the first tab is arranged in the first tab groove, that is, on the basis of providing the first insulating layer, it is ensured that the first tab can be normally installed; since the first tab is arranged in the first tab groove, the thickness at the corresponding position of the first tab is reduced to a certain extent, and then the thickness of the battery cell is reduced, avoiding the occurrence of situations such as a decrease in the energy density per unit volume of the battery cell due to the too large volume of the battery cell to a certain extent. Moreover, the first tab groove can also limit the first tab to a certain extent, improving the connection efficiency and stability of the first tab.

[0013] That is to say, the present utility model improves the problem of short circuit between the positive and negative electrodes, ensures the normal setting of the first tab, avoids the situation of excessive thickness at the first tab to a certain extent, and improves the connection efficiency and stability of the first tab.

[0014] Optionally, a second insulating layer is provided in the first tab groove;

[0015] In the first direction, the second insulating layer is located in the area of the first tab groove close to the edge of the first empty foil area.

[0016] Optionally, in the second direction, the thickness of the second insulating layer and the thickness of the first insulating layer satisfy:

[0017] D ≤ C;

[0018] Wherein, D is the thickness of the second insulating layer, and C is the thickness of the first insulating layer.

[0019] Optionally, in the first direction, the width of the second insulating layer and the width of the first tab groove satisfy:

[0020] E = 0.1F to 0.4F;

[0021] Wherein, E is the width of the second insulating layer, and F is the width of the first tab groove.

[0022] Optionally, in the second direction, the thickness of the first tab, the thickness of the first active layer, and the thickness of the second insulating layer satisfy:

[0023] H + D = 1N to 2.5N;

[0024] Wherein, H is the thickness of the first tab, D is the thickness of the second insulating layer, and N is the thickness of the first active layer.

[0025] Optionally, H + D = 1N to 1.5N.

[0026] Optionally, a third insulating layer is further provided on the first current collector;

[0027] At least a part of the third insulating layer is disposed between the first coating region and the first active layer.

[0028] Optionally, the third insulating layer and the first insulating layer are integrally formed.

[0029] Optionally, a second insulating layer is provided in the first tab groove; in the first direction, the second insulating layer is located in a region of the first tab groove close to the edge of the first empty foil region;

[0030] The first insulating layer, the second insulating layer and the third insulating layer are integrally formed.

[0031] Optionally, the second insulating layer and the first insulating layer are integrally formed.

[0032] Optionally, the first electrode tab further includes a second tab;

[0033] A second tab groove is provided on the first active layer, and the second tab is disposed in the second tab groove.

[0034] Optionally, the second current collector has a bottom coating, the second active layer is disposed on a side of the bottom coating away from the second current collector, and a first clearance groove recessed in a direction away from the first tab groove is provided on the bottom coating corresponding to the first tab.

[0035] Optionally, the second electrode tab includes a winding head portion located in the inner circle of the core and a winding tail portion located in the outer circle of the core;

[0036] The second current collector includes a second empty foil region and a second coating region coated with the second active layer, and the second empty foil region is located in the winding head portion of the second electrode tab and / or the winding tail portion of the second electrode tab;

[0037] A third tab is provided on the second empty foil region, and in the second direction, at least a part of the projection of the third tab overlaps with the projection of the first insulating layer.

[0038] In a second aspect, the present invention provides a battery, including the cell as described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a top view of the head structure of the first electrode tab according to an embodiment of the present invention;

[0040] Figure 2Cross-sectional view of the head structure of the first pole piece according to an embodiment of the present invention;

[0041] Figure 3 is Figure 2 Enlarged view of the structure at I in;

[0042] Figure 4 Schematic diagram of the structure of the battery cell according to an embodiment of the present invention Figure 1 ;

[0043] Figure 5 Partial schematic diagram of the structure of the first clearance groove provided on the second pole piece of the battery cell according to an embodiment of the present invention;

[0044] Figure 6 Schematic diagram of the structure of the battery cell according to an embodiment of the present invention Figure 2 ;

[0045] Figure 7 is Figure 6 Enlarged view of the structure at the second pole ear in.

[0046] Wherein, 1, the first pole piece; 11, the first current collector; 111, the first coating area; 112, the first empty foil area; 12, the first active layer; 121, the second pole ear groove; 13, the first pole ear; 14, the first insulating layer; 141, the first pole ear groove; 15, the second insulating layer; 16, the third insulating layer; 17, the second pole ear; 2, the second pole piece; 21, the second current collector; 210, the second empty foil area; 211, the bottom coating; 212, the first clearance groove; 22, the second active layer; 221, the second clearance groove; 23, the third pole ear; 3, the separator; 100, the battery cell. Detailed implementation manners

[0047] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0048] The core of a wound lithium-ion battery includes a positive electrode sheet, a negative electrode sheet, and a separator. Specifically, the positive electrode sheet, the separator, and the negative electrode sheet are stacked and wound from the inside out to form a core. Among them, the positive electrode sheet includes a positive electrode current collector and a positive electrode active layer provided on the surface of the positive electrode current collector. The negative electrode sheet includes a negative electrode current collector and a negative electrode active layer provided on the surface of the negative electrode current collector. The capacity of the battery is provided by the electrochemical reaction between the active substances of the positive electrode active layer and the negative electrode active layer. The separator is located between the positive electrode sheet and the negative electrode sheet and is used to isolate the contact between the positive electrode sheet and the negative electrode sheet. The core is immersed in the electrolyte and a wound battery is obtained after encapsulation.

[0049] In the existing core, there will be some empty foils on the electrode sheet, which is likely to cause short circuit between the positive and negative electrodes (for example, the burrs in the empty foil area pierce the separator, resulting in short circuit due to contact between the positive and negative electrodes), affecting the safety performance of the battery.

[0050] Based on this, the embodiments of the present invention provide a core and a battery. By providing an insulating layer in the empty foil area of the electrode sheet and providing an ear groove for installing the ear on the insulating layer, the situation of short circuit between the positive and negative electrodes caused by the exposure of the empty foil area is avoided to a certain extent. At the same time, the normal installation of the ear is ensured, and the situation of excessive thickness at the ear is avoided to a certain extent.

[0051] The following will combine the drawings to detail the core and battery provided by the present invention through specific embodiments:

[0052] Refer to Figures 1 to 7 As shown, this embodiment provides a core 100, and the core 100 can specifically be a wound core. The core 100 is applied to a battery, and the battery can be a lithium-ion battery.

[0053] The core 100 provided in this embodiment includes a first electrode sheet 1, a second electrode sheet 2, and a separator 3. Among them, the separator 3 is located between the first electrode sheet 1 and the second electrode sheet 2. The polarities of the first electrode sheet 1 and the second electrode sheet 2 are opposite.

[0054] The first electrode sheet 1 specifically includes: a first current collector 11, a first active layer 12, and a first ear 13. The second electrode sheet 2 specifically includes: a second current collector 21 and a second active layer 22 provided on the second current collector 21.

[0055] The first electrode sheet 1 includes a winding head located in the inner circle of the core and a winding tail located in the outer circle of the core. It should be noted that the winding head can be understood as the area where the electrode sheet starts to wind during the winding process of the core 100, that is, the head area, which is located inside the core 100. Correspondingly, the winding tail can be understood as the area where the electrode sheet winds up.

[0056] Among them, the first current collector 11 includes a first empty foil area 112 and a first coated area 111 coated with a first active layer 12. It can be understood that the first active layer 12 is coated on the first coated area 111, and the first empty foil area 112 is the area on the first current collector 11 where the first active layer 12 is not coated.

[0057] The first empty foil area 112 is located at the winding head and / or the winding tail of the first electrode sheet 1. It can be understood that the first empty foil area 112 is located at the winding head of the first electrode sheet 1, or the first empty foil area 112 is located at the winding tail of the first electrode sheet 1, or both the winding head and the winding tail of the first electrode sheet 1 have the first empty foil area 112.

[0058] Among them, a first insulating layer 14 is provided on the first empty foil area 112, and a first tab groove 141 is provided on the first insulating layer 14, and the first tab 13 is arranged in the first tab groove 141.

[0059] In specific implementation, for example, part of the first insulating layer 14 can be cleaned by means such as cleaning to expose the corresponding first current collector 11, so as to form the first tab groove 141 on the first empty foil area 112.

[0060] Exemplarily, the first tab 13 can be welded in the first tab groove 141 by laser welding. It can be understood that the corresponding first current collector 11 in the first tab groove 141 is exposed, and the first tab 13 is welded to the exposed first current collector 11 in the first tab groove 141. Of course, the first tab 13 can also be connected in the first tab groove 141 by other means.

[0061] The first electrode sheet 1 provided in this embodiment can specifically be a positive electrode sheet. Correspondingly, the first current collector 11 is, for example, an aluminum foil, and the material of the first active layer 12 can be, for example, a ternary material or a lithium iron phosphate and other positive electrode active materials. The first tab 13 is specifically a positive tab. Through the above settings, the empty foil area of the positive electrode sheet can be protected, and the situation of short circuit between the positive and negative electrodes caused by the exposure of the empty foil area is avoided to a certain extent, and the situation of excessive thickness at the positive tab can also be avoided. In addition, the connection efficiency and stability of the positive tab are improved. Correspondingly, the second electrode sheet 2 is a negative electrode sheet.

[0062] Of course, the first electrode sheet 1 can also be a negative electrode sheet. Correspondingly, the first current collector 11 can be, for example, a copper foil, and the material of the first active layer 12 can be, for example, a negative electrode active material such as graphite or silicon-based. The first tab 13 is specifically a negative tab. Correspondingly, the second electrode sheet 2 is a positive electrode sheet.

[0063] By providing a first insulating layer 14 on the first empty foil area 112 of the first electrode tab 1, the first insulating layer 14 can protect this area of the first electrode tab 1, thus to a certain extent avoiding the occurrence of short circuit between the positive and negative electrodes caused by the exposure of the first empty foil area 112. At the same time, a first tab slot 141 is provided on the first insulating layer 14, and the first tab 13 is arranged in the first tab slot 141. That is, on the basis of providing the first insulating layer 14, it is ensured that the first tab 13 can be normally installed. Since the first tab 13 is arranged in the first tab slot 141, the thickness at the corresponding position of the first tab 13 is reduced to a certain extent, and then the thickness of the battery cell 100 is reduced, avoiding to a certain extent the situation such as the reduction of the energy density per unit volume of the battery cell caused by the over-large volume of the battery cell 100. Moreover, the first tab slot 141 can also limit the first tab 13 to a certain extent, improving the connection efficiency and stability of the first tab 13.

[0064] That is to say, the electrode tab provided in this embodiment improves the problem of short circuit between the positive and negative electrodes, ensures the normal arrangement of the first tab 13, avoids the situation of excessive thickness at the first tab 13 to a certain extent, and improves the connection efficiency and stability of the first tab 13.

[0065] During the actual implementation, during the process of connecting the first tab 13 to the first tab slot 141, due to reasons such as improper connection operation, stress at the edge of the electrode tab, and contact stress between the first tab and the first current collector, it is easy to cause the edge of the first tab slot to be torn, thus affecting the quality of the electrode tab. Moreover, if the edge of the first tab slot comes into contact with the corresponding electrode tab, it will cause a short circuit between the adjacent positive and negative electrode tabs. In addition, during the manufacturing process, if there are burrs formed on the edge of the first tab slot, the burrs are likely to pierce the separator of the battery, which will also trigger the risk of battery short circuit.

[0066] Based on this, in some embodiments, continue to refer to Figures 1 to 3 As shown, a second insulating layer 15 is provided in the first tab slot 141. In the first direction, the second insulating layer 15 is located in the area of the first tab slot 141 close to the edge of the first empty foil area 112.

[0067] Refer to Figure 1 As shown, the first direction can be Figure 1 the direction from bottom to top in Figure 1 i.e., the width direction of the electrode tab, and the edge of the first empty foil area 112 here can be

[0068] By setting the second insulating layer 15 in this way, the thickness of the edge region of the bare foil of the electrode can be increased, so that when the first tab 13 is electrically connected to the first current collector 11, the edge of the first tab groove 141 is not easily torn, thereby improving the quality of the electrode. Moreover, due to the presence of the second insulating layer 15, it is possible to avoid the occurrence of a situation where the edge of the first tab groove 141 contacts the second electrode 2 and causes a short circuit of the battery; in addition, such a setting enables the second insulating layer 15 to cover and protect the edge region of the first tab groove 141, thereby to a certain extent avoiding the situation where if there are burrs on the edge of the first tab groove 141, the burrs pierce the diaphragm of the battery and cause a short circuit, further improving the safety performance of the battery.

[0069] If the thickness of the battery cell at the position corresponding to the first tab 13 is too thick, it will cause a decrease in the energy density per unit volume of the battery cell, and the excessive thickness will directly affect the flatness of the battery cell, resulting in uneven pressure on the battery cell during the battery formation process, and further resulting in a longer path during the ion migration process, affecting the electrical performance of the battery.

[0070] Based on this, in some embodiments, in the second direction, the thickness D of the second insulating layer 15 and the thickness C of the first insulating layer 14 satisfy the following relationship:

[0071] D ≤ C;

[0072] Wherein, D is the thickness of the second insulating layer 15, and C is the thickness of the first insulating layer 14.

[0073] Referring to Figure 2 and Figure 3 as shown, the second direction here can be Figure 3 the up and down direction shown in

[0074] That is, the thickness direction of the electrode.

[0075] Continuing to refer to Figure 2 and Figure 3 as shown, exemplarily, the thickness D of the second insulating layer 15 in the second direction is less than the thickness C of the first insulating layer 14 in the second direction.

[0076] Exemplarily, for example, the thickness C of the first insulating layer 14 in the second direction is between 0.5 μm and 20 μm, specifically, for example, it can be 0.5 μm, 5 μm, 6 μm, 7 μm, 7.5 μm, 8 μm, 9 μm, 10 μm, 15 μm, 20 μm. For example, the thickness D of the second insulating layer 15 in the second direction is between 2 μm and 15 μm, specifically, for example, it can be 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 12 μm, 14 μm, 15 μm.

[0077] Referring to Figure 1 As shown, in some embodiments, in the first direction, the width of the second insulating layer 15 and the width of the first tab slot 141 satisfy the following relationship:

[0078] E = 0.1F to 0.4F; where E is the width of the second insulating layer 15 and F is the width of the first tab slot 141.

[0079] Referring to Figure 1 As shown, the first direction here can be Figure 1 the up-down direction shown in

[0080] Such a setting can prevent the first tab 13 and the second insulating layer 15 from overlapping too much in the thickness direction, prevent the situation of excessive thickness at the first tab 13, thereby ensuring the volumetric energy density of the battery cell to a certain extent. At the same time, it can also ensure the flatness of the battery cell to a certain extent, improve the uniformity of the battery cell under pressure, so as to ensure better charge rate performance and cycle performance and other electrical properties of the battery to a certain extent.

[0081] Exemplarily, for example, the width E of the second insulating layer 15 in the first direction is between 0.5 mm and 12 mm, specifically, for example, it can be 0.5 mm, 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 6.25 mm, 7 mm, 8 mm, 9 mm, 10 mm, 11 mm, 12 mm. For example, the width F of the first tab slot 141 in the first direction is between 5 mm and 30 mm, specifically, for example, it can be 5 mm, 10 mm, 15 mm, 17.5 mm, 20 mm, 25 mm, 30 mm.

[0082] Continuing to refer to Figure 2 and Figure 3 As shown, in some embodiments, in the second direction, the thickness of the first tab 13, the thickness of the first active layer 12, and the thickness of the second insulating layer 15 satisfy the following relationship:

[0083] H + D = 1N to 2.5N;

[0084] Wherein, H is the thickness of the first tab 13, D is the thickness of the second insulating layer 15, and N is the thickness of the first active layer 12.

[0085] Referring to Figure 2 and Figure 3 as shown, the above-mentioned second direction can be Figure 2 and Figure 3 the up-and-down direction shown in

[0086] Such a setting can effectively avoid the situation where the first tab 13 is too thick in the second direction, resulting in a decrease in the volume energy density of the battery cell 100. At the same time, it can also ensure the flatness of the battery cell to a certain extent, improve the uniformity of the pressure on the battery cell during the formation process, so as to ensure that the battery has good electrical properties such as charge rate performance and cycle performance to a certain extent.

[0087] Exemplarily, for example, the thickness H of the first tab 13 is between 30 μm and 120 μm, specifically, for example, it can be 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 75 μm, 80 μm, 90 μm, 100 μm, 110 μm, 120 μm. For example, the thickness N of one side of the first active layer 12 is between 10 μm and 100 μm, specifically, for example, it can be 10 μm, 12.8 μm, 30 μm, 40 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, 80 μm, 100 μm. For example, the thickness D of the second insulating layer 15 is between 2 μm and 15 μm, specifically, for example, it can be 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 12 μm, 14 μm, 15 μm.

[0088] Further, specifically, the thickness H of the first tab 13 in the second direction, the thickness N of the first active layer 12 in the second direction, and the thickness D of the second insulating layer 15 in the second direction can satisfy the following relationship:

[0089] H + D = 1N to 1.5N;

[0090] Such a setting can further avoid the situation where the first tab 13 is too thick in the second direction, and further avoid the situation where the volume energy density of the battery cell 100 decreases. At the same time, it further ensures the flatness of the battery cell and further improves the uniformity of the pressure on the battery cell during the formation process, so as to further ensure that the battery has good electrical properties such as charge rate performance and cycle performance.

[0091] Exemplarily, for example, the thickness H of the first tab 13 is between 50 μm and 100 μm, and specifically can be 50 μm, 70 μm, 75 μm, 80 μm, 100 μm. For example, the thickness N of the first active layer 12 is between 36 μm and 108 μm, and specifically can be 36 μm, 50 μm, 72 μm, 90 μm, 108 μm. For example, the thickness D of the second insulating layer 15 is between 3 μm and 8 μm, and specifically can be 3 μm, 5 μm, 5.5 μm, 8 μm.

[0092] If there is contact between the first current collector and the second active layer, between the first current collector and the second current collector, between the first active layer and the second current collector, or between the first active layer and the second active layer between the first electrode tab and the second electrode tab, a short - circuit risk will occur. In addition, if there are burrs on the second electrode tab, the burrs are likely to pierce the separator and contact the first current collector, and a short - circuit situation will also occur. Based on this, in some embodiments, a third insulating layer 16 is further provided on the first current collector 11. Continuing to combine Figures 1 to 3 As shown, in some embodiments, at least part of the third insulating layer 16 is disposed between the first coating area 111 and the first active layer 12.

[0093] Due to the presence of the third insulating layer 16 between the first coating area 111 and the first active layer 12, the third insulating layer 16 can play a role in protecting the first current collector 11, thereby avoiding the occurrence of short - circuit between the positive and negative electrode tabs to a certain extent. For example, even if the first active layer 12 is damaged or destroyed, the presence of the third insulating layer 16 can avoid the situation where the first current collector 11 contacts the second current collector or the second active layer of the second electrode tab 2 and causes a short - circuit to a certain extent. Moreover, this setting also avoids to a certain extent the situation where the burrs on the second electrode tab 2 pierce the separator 3 and contact the first current collector 11 and cause a short - circuit. In addition, this setting further improves the overall structural strength of the first coating area 111.

[0094] In some embodiments, for example, when both the winding head and the winding tail of the first electrode tab 1 have a first empty foil area 112, a first insulating layer 14 may be provided on the first empty foil area 112 at the winding head of the first electrode tab 1, and a third insulating layer 16 may be provided on the first empty foil area 112 at the winding tail of the first electrode tab 1. This enables the third insulating layer 16 to protect the area of the winding tail of the electrode tab, avoiding short - circuiting between the positive and negative electrodes. For example, it can prevent burrs on the opposing electrode tab from piercing the separator 3 and coming into contact with the empty foil area at the tail of the first current collector 11, thus preventing short - circuit situations. Moreover, since the winding tail is located on the outer side of the battery cell, by providing the third insulating layer 16 on the empty foil area at the winding tail of the electrode tab, the rigidity of the empty foil area at the tail can be further improved, enhancing the structural strength of the empty foil area at the tail. Additionally, this setting further improves the insulation performance on the outer side of the battery cell, thereby enhancing the usage safety. For another example, a first insulating layer 14 may also be provided on the first empty foil area 112 at the winding tail of the first electrode tab 1, and a third insulating layer 16 may be provided on the first empty foil area 112 at the winding head of the first electrode tab 1. This enables the third insulating layer 16 to protect the area of the winding head of the electrode tab, avoiding short - circuiting between the positive and negative electrodes. For example, it can prevent burrs on the opposing electrode tab from piercing the separator 3 and coming into contact with the empty foil area at the head of the first current collector 11, thus preventing short - circuit situations.

[0095] In some embodiments, the first insulating layer 14, the second insulating layer 15, and the third insulating layer 16 are integrally formed. That is to say, the first insulating layer 14, the second insulating layer 15, and the third insulating layer 16 are integrally fabricated on the first current collector 11, and then the first active layer 12 is provided on the third insulating layer 16 located in the first coating area 111. This setting simplifies the manufacturing process and is more convenient for the production of electrode tabs.

[0096] Of course, in other embodiments, it may also be that the first insulating layer 14 and the second insulating layer 15 are integrally formed, which makes the production of the electrode tab more convenient. Or, the third insulating layer 16 and the first insulating layer 14 are integrally formed, which is convenient for the production of the electrode tab.

[0097] Specifically, each of the above - mentioned insulating layers may include inorganic fillers, conductive agents, and binders.

[0098] Among them, the inorganic fillers may be selected from one or more of lithium cobalt oxide (LCO), nickel - cobalt - manganese ternary material (NCM), nickel - cobalt - aluminum ternary material (NCA), nickel - cobalt - manganese - aluminum quaternary material (NCMA), lithium iron phosphate (LFP), carbon - coated lithium iron phosphate (C - LFP), lithium manganese phosphate (LMP), lithium manganate (LMO), and lithium - rich manganese - based materials. Or, the inorganic fillers are selected from ceramic materials, specifically one or more of alumina, boehmite, magnesia, and magnesium hydroxide. Or, the inorganic fillers are selected from a mixture of at least one of lithium - containing transition metal oxides and at least one of ceramic materials.

[0099] Among them, the conductive agent is selected from one or more of conductive carbon black, acetylene black, conductive graphite, Ketjen black, carbon nanotubes, and graphene.

[0100] Among them, the binder is selected from one or more of polyvinylidene fluoride, polyacrylonitrile, polyvinylpyrrolidone, and polytetrafluoroethylene.

[0101] Combine Figure 4 and Figure 5 As shown, in some embodiments, a bottom coating 211 is provided on the second current collector 21. Exemplarily, the bottom coating 211 can specifically be a carbon-coated layer. Among them, the second active layer 22 is disposed on a side of the bottom coating 211 away from the second current collector 21.

[0102] By providing the bottom coating 211 on the second current collector 21, the resistance between the second current collector 21 and the active material of the second active layer 22 is reduced, thereby reducing the internal resistance of the battery, and further improving the conductivity of the battery. Moreover, such a setting improves the adhesion and attachment of the second current collector 21 to the active material of the second active layer 22, improves the product yield, and thus reduces the manufacturing cost of the battery. In addition, such a setting can also prevent the second current collector 21 from being corroded and oxidized, improve the service life of the second current collector 21, and thus improve the life of the battery.

[0103] If the thickness of the battery cell at the position corresponding to the first tab 13 is too thick, it will not only reduce the energy density per unit volume of the battery cell, but also directly affect the flatness of the battery cell, resulting in uneven pressure on the battery cell during the battery formation process, and further resulting in a longer path during the ion migration process, affecting the electrical performance of the battery.

[0104] Based on this, in some embodiments, a first clearance groove 212 that is recessed in a direction away from the first tab groove 141 is provided on the bottom coating 211 corresponding to the first tab 13, and the first clearance groove 212 is used to avoid the first tab 13.

[0105] By providing the first clearance groove 212 to avoid the first tab 13, that is, the first clearance groove 212 can accommodate the first tab 13, thereby to a certain extent avoiding the situation where the thickness at the position corresponding to the first tab 13 is too thick and causing a decrease in the energy density per unit volume of the battery cell, and also ensuring the flatness of the battery cell to a certain extent, and further avoiding the situation of uneven pressure on the battery cell during the formation process to a certain extent, improving the charging rate performance and cycle performance of the battery, etc.

[0106] Continue to refer to Figure 4 and Figure 5 As shown, taking the first electrode sheet 1 as the positive electrode sheet and the second electrode sheet 2 as the negative electrode sheet as an example for further illustration:

[0107] Since the first tab 13 is correspondingly arranged in the first uncoated foil area 112, and the first uncoated foil area 112 is an area where the first active layer 12 (such as the positive electrode active layer) is not coated, therefore, referring to Figure 4 and Figure 5 As shown, in specific implementation, the side of the second current collector 21 corresponding to the first tab 13 may not be provided with a second active layer (such as the negative electrode active layer), so as to avoid waste of negative electrode active material and avoid the risk of the cell being too thick at the position corresponding to the first tab 13. That is to say, the active layer is not provided at the position of the bottom coating 211 corresponding to the first tab 13, and the first relief groove 212 is provided on the bottom coating 211 to avoid the first tab 13.

[0108] Combined with Figure 6 and Figure 7 As shown, the first electrode sheet 1 further includes a second tab 17, a second tab groove 121 is provided on the first active layer 12, and the second tab 17 is arranged in the second tab groove 121.

[0109] That is to say, two tabs are provided on the first electrode sheet 1: the first tab 13 and the second tab 17. Among them, the first tab 13 is arranged in the first uncoated foil area 112, and the second tab 17 is arranged in the corresponding area of the first coated area 111. Exemplarily, the first electrode sheet 1 is a positive electrode sheet, and both the first tab 13 and the second tab 17 are positive electrode tabs.

[0110] By providing the first tab 13 and the second tab 17 on the first electrode sheet 1, and correspondingly arranging the first tab 13 in the first uncoated foil area 112 and the second tab 17 in the first coated area 111, when the current is conducted, a part of the current will converge in the direction of the first tab 13 and be led out to the external circuit by the first tab 13, and another part of the current will converge in the direction of the second tab 17 and be led out to the external circuit by the second tab 17. That is to say, multi-tab parallel shunt is adopted to shorten the flowing path of the current, thereby improving the over-current capacity of the battery, reducing the internal resistance of the battery, and further reducing the temperature rise of the battery, so that the rate performance of the battery is improved.

[0111] It can be understood that the first current collector 11 in the second tab groove 121 is exposed, and the second tab 17 can be specifically connected to the first current collector 11 in the second tab groove 121 by laser welding.

[0112] Referring to Figures 4 to 7 As shown, the second electrode sheet 2 has a third tab 23. For example Figure 4 The cell shown in has a first tab 13 and a third tab 23. When the first electrode sheet 1 is a positive electrode sheet and the second electrode sheet 2 is a negative electrode sheet, the cell has one positive electrode tab and one negative electrode tab. For example Figure 6The battery cell shown in the figure has a first tab 13, a second tab 17 and a third tab 23. When the first electrode sheet 1 is the positive electrode sheet and the second electrode sheet 2 is the negative electrode sheet, the battery cell has two positive tabs and one negative tab.

[0113] If the thickness of the battery cell at the position corresponding to the second tab 17 is too thick, it will not only reduce the energy density per unit volume of the battery cell, but also directly affect the flatness of the battery cell, resulting in uneven pressure on the battery cell during the battery formation process, and further resulting in a longer path during the ion migration process, affecting the electrical performance of the battery.

[0114] Based on this, continue to refer to Figure 6 and Figure 7 As shown, a second clearance groove 221 recessed in the direction away from the second tab groove 121 is provided on the second active layer 22 corresponding to the second tab groove 121. The second clearance groove 221 is used to avoid the second tab 17. That is, the second tab 17 is accommodated by the second clearance groove 221. Such a setting can, to a certain extent, avoid the second tab 17 being too thick in the thickness direction, thereby ensuring the energy density per unit volume of the battery cell to a certain extent, and at the same time further ensuring the flatness of the battery cell, improving the uniformity of the pressure on the battery cell, so as to ensure that the battery has good electrical performance such as charge rate performance and cycle performance to a certain extent.

[0115] Combined with Figure 6 and Figure 7 As shown, in some embodiments, in the second direction, the thickness of the second active layer 22, the depth of the second clearance groove 221, the thickness of the second tab 17 and the thickness of the first active layer 12 satisfy:

[0116] M ≤ P, R ≤ N + M;

[0117] Wherein, the second direction here can be Figure 7 the up and down direction shown in the figure. P is the thickness of the second active layer 22; M is the depth of the second clearance groove 221; R is the thickness of the second tab 17, and N is the thickness of the first active layer 12.

[0118] Such a setting can, to a certain extent, avoid the second tab 17 being too thick in the second direction, thereby avoiding the situation that the energy density per unit volume of the battery cell is reduced due to excessive thickness, and also ensuring the flatness of the battery cell to a certain extent, and further avoiding the situation of uneven pressure on the battery cell during the formation process to a certain extent, so as to improve the charge rate performance and cycle performance of the battery.

[0119] Exemplarily, for example, the thickness P of one side of the second active layer 22 is between 10 μm and 80 μm, specifically, for example, it can be 10 μm, 15 μm, 20 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, 80 μm. For example, the thickness R of the second tab 17 is between 22.8 μm and 200 μm, specifically, for example, it can be 22.8 μm, 40 μm, 60 μm, 100 μm, 110 μm, 111 μm, 111.5 μm, 120 μm, 150 μm, 180 μm, 200 μm. For example, the thickness N of one side of the first active layer 12 is between 10 μm and 100 μm, specifically, for example, it can be 10 μm, 12.8 μm, 30 μm, 40 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, 80 μm, 100 μm. For example, the depth M of the second clearance groove 221 is between 10 μm and 70 μm, specifically, for example, it can be 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm.

[0120] In some embodiments, in the third direction, the width of the second tab 17 and the width of the second clearance groove 221 satisfy the following relationship:

[0121] J ≤ K;

[0122] Wherein, the third direction herein can be Figure 6 and Figure 7 the left - right direction shown in. J is the width of the second tab 17, and K is the width of the second clearance groove 221.

[0123] Such a setting can ensure the effective avoidance of the second tab 17 by the second clearance groove 221, that is, the second clearance groove 221 can accommodate the second tab 17, thereby further avoiding the risk of excessive thickness at the second tab 17.

[0124] Exemplarily, for example, the width J of the second tab 17 is specifically between 3 mm and 10 mm, specifically, for example, it can be 3 mm, 4 mm, 5 mm, 6 mm, 6.5 mm, 7 mm, 8 mm, 9 mm, 10 mm. For example, the width K of the second clearance groove 221 is specifically between 4 mm and 12 mm, specifically, for example, it can be 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 11 mm, 12 mm.

[0125] Refer to Figures 4 to 7As shown, the second pole piece 2 includes a winding head located in the inner circle of the core and a winding tail located in the outer circle of the core. Specifically, the second current collector 21 includes a second empty foil area 210 and a second coated area coated with the second active layer 22. It can be understood that the second active layer 22 is coated on the second coated area, and the second empty foil area 210 is the area on the second current collector 21 where the second active layer 22 is not coated.

[0126] Among them, the second empty foil area 210 is located at the winding head and / or the winding tail of the second pole piece 2. It can be understood that the second empty foil area 210 is located at the winding head of the second pole piece 2, or the second empty foil area 210 is located at the winding tail of the second pole piece 2, or both the winding head and the winding tail of the second pole piece 2 have the second empty foil area 210.

[0127] Among them, the third tab 23 is specifically arranged on the second empty foil area 210. In some embodiments, in the second direction (the second direction can be the up and down direction shown in Figure 6 ), the projection of the third tab 23 overlaps at least partially with the projection of the first insulating layer 14.

[0128] Such an arrangement can, to a certain extent, prevent the situation where if there are burrs on the third tab 23, the burrs pierce the separator 3 and then damage the first pole piece 1 corresponding to the third tab 23, thereby effectively protecting the first pole piece 1.

[0129] Continuing to refer to Figure 6 As shown, in some embodiments, the winding head of the first pole piece 1 has a first empty foil area 112, the winding head of the second pole piece 2 has a second empty foil area 210, and the third tab 23 is specifically arranged on the second empty foil area 210 located at the winding head of the second pole piece 2. Among them, in the above-mentioned second direction, the projection of the third tab 23 overlaps at least partially with the projection of the first insulating layer 14 on the first empty foil area 112 located at the winding head of the first pole piece 1. Such an arrangement effectively protects at least the winding head of the first pole piece 1, thereby improving the strength and structural stability of the core head.

[0130] In other embodiments, it can also be that the winding tail of the first pole piece 1 has a first empty foil area 112, the winding tail of the second pole piece 2 has a second empty foil area 210, and the third tab 23 is specifically arranged on the second empty foil area 210 located at the winding tail of the second pole piece 2. Among them, in the above-mentioned second direction, the projection of the third tab 23 overlaps at least partially with the projection of the first insulating layer 14 on the first empty foil area 112 located at the winding tail of the first pole piece 1. Such an arrangement effectively protects at least the winding tail of the first pole piece 1, thereby improving the strength and structural stability of the core tail.

[0131] This embodiment also provides a battery, which may be a lithium-ion battery, for example. The battery can be used as a power source or an energy storage unit of an electronic device, and the electronic device can be, but is not limited to, a mobile device (such as a mobile phone, a laptop computer, a tablet computer, etc.), an electric vehicle (such as a pure electric vehicle, a hybrid electric vehicle, an electric bicycle, etc.).

[0132] Specifically, the battery includes a battery cell, and the structure and implementation principle of this battery cell are the same as those of the battery cell 100 provided in the above embodiment, and can bring the same or similar technical effects, which will not be elaborated one by one here. For details, reference can be made to the description of the above embodiment.

[0133] In this article, it should be noted that unless otherwise clearly defined and limited, the terms "installation", "connection", and "coupling" should be understood in a broad sense. For example, it can be a fixed connection, or an indirect connection through an intermediate medium. It can be the internal communication of two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances. In addition, the orientation or positional relationship indicated by the terms "upper", "lower", "left", "right", "front", "rear", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing this application and simplifying the description, rather than indicating or implying that the device or component referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to this application.

[0134] In this article, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "including one..." does not exclude the existence of another identical element in the process, method, article or device including the said element.

[0135] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modification, equivalent replacement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A battery cell, characterized in that: The battery cell comprises a first pole piece (1), a second pole piece (2), and a diaphragm (3) located between the first pole piece (1) and the second pole piece (2); The first pole piece (1), the diaphragm (3) and the second pole piece (2) are stacked and wound to form a winding core; The first pole piece (1) comprises a first current collector (11), a first active layer (12) and a first pole lug (13); The second pole piece (2) comprises a second current collector (21) and a second active layer (22) arranged on the second current collector (21); The first pole piece (1) comprises a winding head located at the inner circle of the winding core and a winding tail located at the outer circle of the winding core; The first current collector (11) comprises a first empty foil area (112) and a first coating area (111) coated with the first active layer (12), wherein the first empty foil area (112) is located at the winding head and / or the winding tail of the first pole piece (1); A first insulating layer (14) is provided on the first empty foil area (112), and a first pole lug groove (141) is provided on the first insulating layer (14), and the first pole lug (13) is provided in the first pole lug groove (141).

2. The battery cell according to claim 1, characterized in that: A second insulating layer (15) is provided in the first electrode tab groove (141); Along the first direction, the second insulating layer (15) is located in a region of the first electrode tab groove (141) close to an edge of the first empty foil region (112).

3. The battery cell according to claim 2, characterized in that: In the second direction, the thickness of the second insulating layer (15) and the thickness of the first insulating layer (14) satisfy: D≤C; Wherein, D is the thickness of the second insulating layer (15), and C is the thickness of the first insulating layer (14).

4. The battery cell according to claim 2, characterized in that: Along the first direction, the width of the second insulating layer (15) and the width of the first electrode tab groove (141) satisfy: E = 0.1F ~ 0.4F; Wherein, E is the width of the second insulating layer (15), and F is the width of the first electrode tab groove (141).

5. The battery cell according to claim 2, characterized in that: In the second direction, the thickness of the first electrode tab (13), the thickness of the first active layer (12) and the thickness of the second insulating layer (15) satisfy: H+D=1N~2.5N; Wherein, H is the thickness of the first electrode tab (13), D is the thickness of the second insulating layer (15), and N is the thickness of the first active layer (12).

6. The battery cell according to claim 1, characterized in that: A third insulating layer (16) is also provided on the first current collector (11); At least a portion of the third insulating layer (16) is disposed between the first coating region (111) and the first active layer (12).

7. The battery cell according to claim 6, characterized in that: The third insulating layer (16) and the first insulating layer (14) are integrally formed; or, A second insulating layer (15) is arranged in the first pole tab groove (141); along the first direction, the second insulating layer (15) is located in a region of the first pole tab groove (141) close to an edge of the first empty foil region (112); The first insulating layer (14), the second insulating layer (15) and the third insulating layer (16) are integrally formed.

8. The battery cell according to any one of claims 1 to 7, characterized in that: The first pole piece (1) further comprises a second pole lug (17); A second pole lug groove (121) is provided on the first active layer (12), and the second pole lug (17) is arranged in the second pole lug groove (121).

9. The battery cell according to any one of claims 1 to 7, characterized in that: The second current collector (21) has a primer layer (211), the second active layer (22) is arranged on a side of the primer layer (211) away from the second current collector (21), and a first avoidance groove (212) is provided on the primer layer (211) corresponding to the first pole lug (13) and is recessed in a direction away from the first pole lug groove (141).

10. The battery cell according to any one of claims 1 to 7, characterized in that: The second pole piece (2) comprises a winding head portion located at the inner circle of the winding core and a winding tail portion located at the outer circle of the winding core; The second current collector (21) comprises a second empty foil area (210) and a second coating area coated with the second active layer (22), wherein the second empty foil area (210) is located at the winding head of the second pole piece (2) and / or the winding tail of the second pole piece (2); A third pole tab (23) is arranged on the second empty foil area (210), and along the second direction, a projection of the third pole tab (23) at least partially overlaps with a projection of the first insulating layer (14).

11. The battery cell according to claim 5, characterized in that: H+D=1N~1.5N.

12. A battery, characterized in that: Comprising the battery cell as claimed in any one of claims 1 to 11.

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