Lithium ion battery

Abstract

The utility model discloses a lithium ion battery, which relates to the technical field of lithium ion batteries and comprises a packaging film and a battery cell. The battery cell is packaged in the packaging film and comprises a first pole piece, a second pole piece and a diaphragm positioned between the first pole piece and the second pole piece; the first pole piece comprises a first tab, and the second pole piece comprises a second tab; the first pole piece comprises a first gap, and the first tab is located in the first gap; the second pole piece comprises a third gap, and the second tab is located in the third gap; the diaphragm is provided with a first opening and a second opening corresponding to the third notch and the first notch respectively. According to the lithium ion battery provided by the utility model, the gaps for accommodating the tabs are formed in the pole pieces of the battery cell, so that the packaging film is attached to the end surfaces of the battery cell on the two sides of the gaps, the gap between the battery cell and the packaging film is reduced, the proportion of the battery cell in the lithium ion battery is increased, and the energy density of the lithium ion battery is further improved.

Description

Technical Field

[0001] The utility model relates to the technical field of lithium ion batteries, and more specifically, to a lithium ion battery. Background Art

[0002] The laminated lithium-ion battery is an important construction method in modern battery technology. The battery core is formed by stacking the positive and negative electrodes and the separator layer by layer. The soft pole ears arranged at the ends of each electrode are welded to the corresponding external hard pole ears respectively, and the battery core is encapsulated in the packaging film at the same time.

[0003] In order to facilitate the connection between the external hard pole ear and the soft pole ear, a bending portion is formed in the packaging film for the external hard pole ear. However, since the soft pole ear is arranged at the end of the pole piece, a large gap will be left between the battery cell and the packaging film, thereby reducing the proportion of the battery cell used to provide battery capacity in the lithium-ion battery, which is not conducive to the improvement of the energy density of the lithium-ion battery.

[0004] Therefore, how to reduce the gap between the battery cell and the packaging film and improve the energy density of the lithium-ion battery has become a technical problem that needs to be solved urgently by those skilled in the art. Utility Model Content

[0005] In view of this, an object of the present invention is to provide a lithium ion battery to reduce the gap between the battery core and the packaging film and improve the energy density of the lithium ion battery.

[0006] In order to achieve the above purpose, the utility model provides the following technical solutions:

[0007] A lithium-ion battery, comprising:

[0008] Packaging film;

[0009] A battery cell, wherein the battery cell is encapsulated in the packaging film, and 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;

[0010] The first pole piece includes a first pole lug, and the second pole piece includes a second pole lug;

[0011] The first pole piece comprises a first notch, and the first pole ear is located in the first notch;

[0012] The second pole piece comprises a third notch, and the second pole lug is located in the third notch;

[0013] The diaphragm is provided with a first opening and a second opening corresponding to the third notch and the first notch respectively.

[0014] Optionally, in the above lithium-ion battery, the battery cell further comprises a first external pole lug connected to the first pole lug and a second external pole lug connected to the second pole lug;

[0015] At least part of the first external terminal is located in the first notch; and / or,

[0016] At least a portion of the second external electrode tab is located in the third notch.

[0017] Optionally, in the above lithium-ion battery, the first pole piece comprises a second notch, and at least a portion of the second pole tab is located in the second notch; and / or,

[0018] The second pole piece includes a fourth notch, and at least a portion of the first pole tab is located in the fourth notch.

[0019] Optionally, in the above lithium-ion battery, the width of the fourth notch of the second pole piece is smaller than the width of the first notch of the first pole piece; and / or,

[0020] The width of the third notch of the second pole piece is smaller than the width of the second notch of the first pole piece; and / or,

[0021] The depth of the first notch of the first pole piece is greater than the depth of the fourth notch of the second pole piece; and / or,

[0022] The depth of the second notch of the first pole piece is greater than the depth of the third notch of the second pole piece.

[0023] Optionally, in the above lithium-ion battery, the difference between the width of the first notch and the width of the fourth notch is 0 to 2.0 mm; and / or,

[0024] The difference between the width of the second notch and the width of the third notch is 0 to 2.0 mm; and / or,

[0025] The difference between the depth of the first notch of the first pole piece and the depth of the fourth notch of the second pole piece is 0 to 3.0 mm; and / or,

[0026] The difference between the depth of the second notch of the first pole piece and the depth of the third notch of the second pole piece is 0-3.0 mm.

[0027] Optionally, in the above lithium-ion battery, a depth of the third notch and / or the fourth notch of the second pole sheet is D, and 0.5 mm<D<3.0 mm.

[0028] Optionally, in the above lithium-ion battery, the opening depth of the diaphragm is less than the depth of the third notch of the second pole piece.

[0029] Optionally, in the above lithium-ion battery, the width of the first opening is smaller than the width of the second notch of the first pole piece; and / or,

[0030] The width of the first opening is smaller than the width of the third notch of the second pole piece; and / or,

[0031] The width of the second opening is smaller than the width of the first notch of the first pole piece; and / or,

[0032] The width of the second opening is smaller than the width of the fourth notch of the second pole piece.

[0033] Optionally, in the above lithium-ion battery, the difference between the width of the third notch and the width of the first opening is 0 to 2.0 mm; and / or,

[0034] The difference between the width of the fourth notch and the width of the second opening is 0-2.0 mm.

[0035] Optionally, in the above lithium-ion battery, a side edge of the first opening is located on a side edge of the second notch of the first pole piece close to the second notch; and / or,

[0036] The side edge of the second opening is located on a side edge of the first notch of the first pole piece close to the first notch.

[0037] Optionally, in the above lithium-ion battery, first chamfers are provided at the four corners of the first pole piece, a second chamfer is provided at the top of the first notch of the first pole piece, and a third chamfer is provided at the bottom of the first notch of the first pole piece.

[0038] Optionally, in the above lithium-ion battery, the radius of the second chamfered portion is smaller than the radius of the first chamfered portion; and / or,

[0039] The radius of the third chamfered portion is smaller than the radius of the first chamfered portion.

[0040] Optionally, in the above lithium-ion battery, the radius of the first chamfered portion is 0.5 mm to 3.0 mm; and / or,

[0041] The radius of the second chamfered portion is 0 to 1.5 mm; and / or,

[0042] The radius of the third chamfered portion is 0 to 1.5 mm.

[0043] The lithium ion battery provided by the utility model provides a first notch on the first pole piece of the battery cell so that the first pole ear is located in the first notch, and provides a third notch on the second pole piece of the battery cell so that the second pole ear is located in the third notch, and at the same time, a first opening and a second opening corresponding to the third notch and the first notch respectively are provided on the diaphragm between the first pole piece and the second pole piece, so that when the battery cell is packaged in a packaging film, the packaging film can be fitted with the end faces of the battery cell on both sides of the notch, so as to reduce the gap between the battery cell and the packaging film, increase the proportion of the battery cell in the lithium ion battery, and further improve the energy density of the lithium ion battery.

[0044] The technical features mentioned above, the technical features to be mentioned below, and the technical features shown separately in the drawings can be combined with each other arbitrarily, as long as the combined technical features are not contradictory. All feasible feature combinations are technical contents clearly recorded in this article. Any of the multiple sub-features contained in the same sentence can be applied independently, and does not have to be applied together with other sub-features. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are merely embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0046] Figure 1 A schematic diagram of the structure of a lithium-ion battery provided in an embodiment of the utility model;

[0047] Figure 2 The embodiment of the utility model provides Figure 1 a1-a1 cross-section diagram;

[0048] Figure 3 The embodiment of the utility model provides Figure 1 Schematic diagram of the b1-b1 section;

[0049] Figure 4 The embodiment of the utility model provides Figure 1 Schematic diagram of the c1-c1 section;

[0050] Figure 5 A schematic diagram of the structure of a first pole piece provided in an embodiment of the utility model;

[0051] Figure 6 A schematic diagram of the chamfer of the first pole piece provided in an embodiment of the utility model;

[0052] Figure 7A schematic diagram of the structure of the second pole piece provided in an embodiment of the utility model;

[0053] Figure 8 A schematic diagram of the chamfer of the second pole piece provided in an embodiment of the utility model;

[0054] Fig. 9 A schematic diagram of the structure of the diaphragm provided in an embodiment of the utility model;

[0055] Fig.10 This is a schematic diagram of the assembly of the second pole piece and the diaphragm provided in an embodiment of the utility model.

[0056] Among them, 100 is packaging film;

[0057] 200 is a battery cell, 201 is a first pole piece, 2011 is a first notch, 2012 is a second notch, 2013 is a first active material, 202 is a second pole piece, 2021 is a third notch, 2022 is a fourth notch, 2023 is a second active material, 203 is a diaphragm, 2031 is a first opening, 2032 is a second opening, 204 is a first pole ear, 205 is a second pole ear, 206 is a first chamfered portion, 207 is a second chamfered portion, and 208 is a third chamfered portion;

[0058] 300 is an external pole lug, 301 is a first external pole lug, and 302 is a second external pole lug. DETAILED DESCRIPTION

[0059] The core of the utility model is to provide a lithium ion battery to reduce the gap between the battery core and the packaging film and improve the energy density of the lithium ion battery.

[0060] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0061] Lithium-ion batteries, as an important device for modern energy storage, are widely used in electric vehicles, portable electronic devices and other fields. In the manufacturing process of lithium-ion batteries, battery assembly is an important link, which directly affects the performance and safety of the battery. The basic components of lithium-ion batteries include core materials such as positive electrode sheets, negative electrode sheets, diaphragms and electrolytes. These materials are combined into battery cells through specific processes, and the structural forms of battery cells are mainly divided into two types: laminated structure and wound structure.

[0062] The laminated lithium-ion battery is an important construction method in modern battery technology. The battery core is formed by stacking the positive and negative electrodes and the separator layer by layer. The soft pole ears arranged at the ends of each electrode are welded to the corresponding external hard pole ears respectively, and the battery core is encapsulated in the packaging film at the same time.

[0063] In order to facilitate the connection between the external hard pole ear and the soft pole ear, a bending portion is formed in the packaging film for the external hard pole ear. However, since the soft pole ear is arranged at the end of the pole piece, a large gap will be left between the battery cell and the packaging film, thereby reducing the proportion of the battery cell used to provide battery capacity in the lithium-ion battery, which is not conducive to the improvement of the energy density of the lithium-ion battery.

[0064] For this reason, Figures 1 to 10 As shown, the embodiment of the utility model discloses a lithium ion battery, including a packaging film 100 and a battery cell 200. A first notch 2011 is provided on the first pole piece 201 of the battery cell 200, so that the first pole ear 204 is located in the first notch 2011, and a third notch 2021 is provided on the second pole piece 202 of the battery cell 200, so that the second pole ear 205 is located in the third notch 2021, and at the same time, a first opening 2031 and a second opening 2032 corresponding to the third notch 2021 and the first notch 2011 are provided on the diaphragm 203 between the first pole piece 201 and the second pole piece 202, respectively, so that when the battery cell 200 is packaged in the packaging film 100, the packaging film 100 can be attached to the end faces of the battery cell 200 on both sides of the notch, so as to reduce the gap between the battery cell 200 and the packaging film 100, increase the proportion of the battery cell 200 in the lithium ion battery, and thus improve the energy density of the lithium ion battery.

[0065] The following will be combined Figures 1 to 10 The lithium-ion battery disclosed in the embodiment of the utility model is specifically explained and illustrated.

[0066] like Figures 1 to 4 As shown, the battery cell 200 is encapsulated in the packaging film 100, and the battery cell 200 includes a first pole piece 201, a second pole piece 202, and a separator 203 located between the first pole piece 201 and the second pole piece 202. The first pole piece 201 and the second pole piece 202 have different polarities, and the separator 203 is arranged between the first pole piece 201 and the second pole piece 202 to prevent the two pole pieces from contacting each other and causing a short circuit, while ensuring the free flow of electrolyte ions.

[0067] Among them, Figure 5 As shown, the first pole piece 201 includes a first pole ear 204 and a first notch 2011 for accommodating the first pole ear 204. The first pole ear 204 is located in the first notch 2011, and the first pole ear 204 has the same polarity as the first pole piece 201. Figure 7As shown, the second pole piece 202 includes a second pole ear 205 and a third notch 2021 for accommodating the second pole ear 205, the second pole ear 205 is located in the third notch 2021, and the second pole ear 205 has the same polarity as the second pole piece 202. At the same time, the diaphragm 203 is provided with a first opening 2031 corresponding to the third notch 2021 and a second opening 2032 corresponding to the first notch 2011, so as to avoid affecting the connection between the pole ear and the external pole ear 300. When the battery cell 200 is packaged, since the first pole ear 204 and the second pole ear 205 are respectively located in the first notch 2011 and the third notch 2021, the end faces of the battery cell 200 on both sides of the notch can be attached to the packaging film 100, thereby reducing the gap between the battery cell 200 and the packaging film 100, increasing the proportion of the battery cell 200 in the lithium-ion battery, and thus improving the energy density of the lithium-ion battery.

[0068] It should be noted that, in the above embodiment, the packaging film 100 may be, but is not limited to, an aluminum-plastic film, which is not limited herein.

[0069] Furthermore, if Figures 1 to 4 As shown, the external electrode tab 300 includes a first external electrode tab 301 connected to the first electrode tab 204 and a second external electrode tab 302 connected to the second electrode tab 205. Among them, at least part of the first external electrode tab 301 is located in the first notch 2011 and connected to the first electrode tab 204, and / or, at least part of the second external electrode tab 302 is located in the third notch 2021 and connected to the second electrode tab 205, that is, part of the first external electrode tab 301 is located in the first notch 2011 and connected to the first electrode tab 204, or part of the second external electrode tab 302 is located in the third notch 2021 and connected to the second electrode tab 205, or part of the first external electrode tab 301 is located in the first notch 2011 and part of the second external electrode tab 302 is located in the third notch 2021, and connected to the first electrode tab 204 and the second electrode tab 205, respectively. Specifically, a first bending portion is provided at one end of the first external pole ear 301, and is welded and fixed to the first pole ear 204 through the first bending portion of the first external pole ear 301; a second bending portion is provided at one end of the second external pole ear 302, and is welded and fixed to the second pole ear 205 through the second bending portion of the second external pole ear 302; and the other ends of the first external pole ear 301 and the second external pole ear 302 are extended out of the sealing portion of the packaging film 100 so as to be connected to other electrical equipment, and a sealing device is used to seal the packaging film 100. In addition, the first external pole ear 301 and the second external pole ear 302 can be fixed.

[0070] Furthermore, if Figures 2 to 4As shown, the battery cell 200 includes a plurality of pole pieces of different polarities, that is, a first pole piece 201, a second pole piece 202 and a diaphragm 203 located between the first pole piece 201 and the second pole piece 202 are multiple, and the first pole piece 201, the second pole piece 202 and the diaphragm 203 are stacked alternately, that is, they are stacked in the order of the first pole piece 201, the diaphragm 203, the second pole piece 202, the diaphragm 203 and the first pole piece 201, or they are stacked in the order of the second pole piece 202, the diaphragm 203, the first pole piece 201, the diaphragm 203 and the second pole piece 202.

[0071] like Figures 5 to 8 As shown, in a specific embodiment, the first pole piece 201 includes a second notch 2012 for accommodating the second pole ear 205, and when the pole pieces are staggered and stacked, at least a portion of the second pole ear 205 is located in the second notch 2012, and / or the second pole piece 202 includes a fourth notch 2022 for accommodating the first pole ear 204, and when the pole pieces are staggered and stacked, at least a portion of the first pole ear 204 is located in the fourth notch 2022, that is, a portion of the second pole ear 205 is located in the second notch 2012, or a portion of the first pole ear 204 is located in the fourth notch 2022, or a portion of the second pole ear 205 is located in the second notch 2012 and a portion of the first pole ear 204 is located in the fourth notch 2022.

[0072] Specifically, Figures 5 to 7 As shown, for ease of understanding, the first pole piece 201 is set as the positive pole piece, and the second pole piece 202 is set as the negative pole piece. Among them, the first pole piece 201 includes a first current collector and a first active material 2013 coated on the first current collector, and the second pole piece 202 includes a second current collector and a second active material 2023 coated on the second current collector. In this embodiment, the first current collector can be made of aluminum foil, so that the first pole piece 201 has good chemical stability and a high oxidation potential, so that it can maintain stable performance during the charging and discharging process of the lithium-ion battery, is not easily corroded by the electrolyte, and has good conductivity, which is conducive to the efficient transmission of electrons. The second current collector can be made of copper foil to ensure the electrochemical stability of the second pole piece 202 within the operating voltage range of the lithium-ion battery, and has a low tendency to form alloys with lithium, thereby ensuring the structural stability of the surface of the second current collector during the cycle, which is conducive to maintaining the long-term performance of the lithium-ion battery. Furthermore, the first active material 2013 may be any one of lithium cobalt oxide, lithium nickel cobalt manganese oxide or lithium iron phosphate, and the second active material 2023 may be any one of graphite material, titanium-based material, silicon-based material or nitride, which is not limited herein.

[0073] Further, the increase in the thickness of the first active material 2013 and the second active material 2023 can increase the capacity of the lithium-ion battery, but too large a thickness will increase the electron transmission path and reduce the power density of the lithium-ion battery, and the thickness of the first current collector and the second current collector will directly affect its conductivity. Generally speaking, a thinner current collector has a higher resistance, which will lead to an increase in the internal resistance of the lithium-ion battery, thereby affecting the charge and discharge efficiency of the lithium-ion battery. In order to optimize the performance of the lithium-ion battery, the difference between the thickness of the first active material 2013 and the thickness of the first current collector is 10mm to 100mm, and / or, the difference between the thickness of the second active material 2023 and the thickness of the second current collector is 10mm to 100mm, so as to improve the energy density, power output, cycle life and safety of the lithium-ion battery, so that it can be accurately adjusted according to the needs of different application scenarios. It should be noted that in this embodiment, the thickness of the first active material 2013 and the thickness of the second active material 2023 both refer to the thickness coated on a single side of the current collector.

[0074] Furthermore, if Figure 5 and Figure 7 As shown, the width of the fourth notch 2022 of the second pole piece 202 is defined as M, the width of the first notch 2011 of the first pole piece 201 is defined as m, and the width of the third notch 2021 of the second pole piece 202 is defined as N, and the width of the second notch 2012 of the first pole piece 201 is defined as n. At the same time, the depths of the first notch 2011 and the second notch 2012 of the first pole piece 201 are defined as d, and the depths of the third notch 2021 and the fourth notch 2022 of the second pole piece 202 are defined as D. The width of the fourth notch 2022 of the second pole piece 202 is smaller than the width of the first notch 2011 of the first pole piece 201, that is, M<m, and / or the width of the third notch 2021 of the second pole piece 202 is smaller than the width of the second notch 2012 of the first pole piece 201, that is, N<n, and / or the depth of the first notch 2011 of the first pole piece 201 is greater than the depth of the fourth notch 2022 of the second pole piece 202, and / or the depth of the second notch 2012 of the first pole piece 201 is greater than the depth of the third notch 2012 of the second pole piece 202. The depth of the three notches 2021, in this embodiment, can be equal to the depth of the first notch 2011 and the second notch 2012, and the depth of the third notch 2021 and the fourth notch 2022, that is, d>D, to prevent the burrs on the edges of the first notch 2011 and the second notch 2012 of the first pole piece 201 from piercing the diaphragm 203 and contacting the second pole piece 202 to cause a short circuit, while ensuring that the second pole piece 202 has enough space to carry the lithium ions of the first pole piece 201, avoiding the generation of lithium dendrites and preventing the precipitation of lithium ions. In addition, by setting asymmetric notches on each pole piece, the current distribution between the electrodes can be optimized, the resistance between the electrodes can be reduced, and the performance and efficiency of the lithium-ion battery can be improved.

[0075] In a specific embodiment, the difference between the width of the first notch 2011 and the width of the fourth notch 2022 is 0 to 2.0 mm, that is, 0 < m - M < 2.0 mm, and / or the difference between the width of the second notch 2012 and the width of the third notch 2021 is 0 to 2.0 mm, that is, 0 < n - N < 2.0 mm, and / or the difference between the depth of the first notch 2011 of the first electrode 201 and the depth of the fourth notch 2022 of the second electrode 202 is 0 to 3.0 mm, that is, 0 < d - D < 3.0 mm, and / or the difference between the depth of the second notch 2012 of the first electrode 201 and the depth of the third notch 2021 of the second electrode 202 is 0 to 3.0 mm, that is, 0 < d - D < 3.0 mm. By controlling the difference between the notch width of the first electrode 201 and the notch width of the second electrode 202 within 0 to 2.0 mm, not only can the burrs on the edges of the first notch 2011 and the second notch 2012 of the first electrode 201 be prevented from piercing the separator 203, ensuring that the second electrode 202 has enough space to carry the lithium ions of the first electrode 201, but also the current distribution and heat distribution between the positive and negative electrodes can be effectively balanced, preventing heat concentration, and at the same time, the resistance between the electrodes can be reduced.

[0076] Furthermore, as Figure 7 and Fig.10 shown, in a specific embodiment, the depths of the third notch 2021 and the fourth notch 2022 of the second electrode 202 are 0.5 mm to 3.0 mm, that is, 0.5 mm < D < 3.0 mm. At the same time, the opening depth of the separator 203 is defined as e, and 0 < e < D, that is, the opening depth of the separator 203 is less than the depth of the third notch 2021 of the second electrode 202. Specifically, the opening depth of the separator 203 is 0 to 3.0 mm, that is, 0 < e < 3.0 mm. By making the opening edge of the separator 203 extend beyond the bottom edge of the corresponding notch of the second electrode 202, it is beneficial to the stable arrangement of the internal components of the lithium-ion battery, and the second tab 205 of the second electrode 202 can be effectively fixed, preventing the electrode or tab from shifting or deforming, which may cause the instability of the lithium-ion battery structure. If the opening depth of the separator 203 exceeds 3 mm, it will affect the overall energy density of the battery cell 200, and it is easy to cause the second tab 205 to contact the first electrode 201 and cause a short circuit.

[0077] Furthermore, as Fig. 9As shown, for ease of understanding, the width of the first opening 2031 is defined as Y, and the width of the second opening 2032 is defined as X. Wherein, the width of the first opening 2031 is smaller than the width of the second notch 2012 of the first pole piece 201, that is, Y<n, and / or, the width of the first opening 2031 is smaller than the width of the third notch 2021 of the second pole piece 202, that is, Y<N, and / or, the width of the second opening 2032 is smaller than the width of the first notch 2011 of the first pole piece 201, that is, X<m, and / or, the width of the second opening 2032 is smaller than the width of the fourth notch 2022 of the second pole piece 202, that is, X<M, to prevent abnormal reactions between the diaphragm 203 and the pole ear, such as needle short circuit or overvoltage, thereby improving the safety of the lithium-ion battery. At the same time, the narrower diaphragm 203 opening helps to increase the contact area between the diaphragm 203 and the pole piece, promote the diffusion of electrolyte and ion conduction, thereby improving the energy density and power output of the lithium-ion battery.

[0078] In a specific embodiment, the difference between the width of the third notch 2021 and the width of the first opening 2031 is 0-2.0 mm, that is, 0<MX<2.0 mm, and / or the difference between the width of the fourth notch 2022 and the width of the second opening 2032 is 0-2.0 mm, that is, 0<NY<2.0 mm. By controlling the difference between the notch width of the second pole piece 202 and the opening width of the diaphragm 203 to 0-2.0 mm, interference with the bending and welding of the pole lugs on the pole piece can be avoided, the welding strength can be improved, and the occurrence of cold welding can be prevented.

[0079] Furthermore, the side of the first opening 2031 is located on the side of the second notch 2012 of the first pole piece 201, close to the second notch 2012, and / or the side of the second opening 2032 is located on the side of the first notch 2011 of the first pole piece 201, close to the first notch 2011, thereby preventing the positive and negative pole pieces from being misaligned and causing a short circuit, and at the same time, preventing the diaphragm 203 from thermal shrinkage.

[0080] Furthermore, if Figure 6 and Figure 8As shown, first chamfered portions 206 are provided at the four corners of the electrode tab. The chamfer radius of the first chamfered portions 206 is defined as R. A second chamfered portion 207 is provided at the top of the first notch 2011 of the first electrode tab 201, and the chamfer radius of the second chamfered portion 207 is defined as r1. A third chamfered portion 208 is provided at the bottom of the first notch 2011 of the first electrode tab 201, and the chamfer radius of the third chamfered portion 208 is defined as r2. Among them, the radius of the second chamfered portion 207 is smaller than the radius of the first chamfered portion 206, that is, r1 < R, which can effectively enhance the structural stability of the electrode tab, so as to ensure that the electrode tabs of the stacked cell 200 are not easily deformed or damaged during assembly and use, extend the stability of the life of the lithium-ion battery, and simplify the manufacturing process and reduce the production cost. And / or, the radius of the third chamfered portion 208 is smaller than the radius of the first chamfered portion 206, that is, r2 < R, which can reduce the resistance inside the electrode tab, ensure that there is still an active material connection at the notch of the electrode tab, so as to maintain the fluidity of the circuit, and can better control the current distribution inside the lithium-ion battery, reduce the current concentration between the electrode tabs and the generation of local hot spots, thereby improving the safety and stability of the lithium-ion battery. In this embodiment, the radius of the first chamfered portion 206 can be 0.5 mm to 3.0 mm, that is, 0.5 mm < R < 3.0 mm, and / or, the radius of the second chamfered portion 207 can be 0 to 1.5 mm, that is, 0 < r1 < 1.5 mm, and / or, the radius of the third chamfered portion 208 can be 0 to 1.5 mm, that is, 0 < r2 < 1.5 mm.

[0081] It should be noted that only the embodiment of providing chamfered portions at the positions of the first electrode tab 201 and the first notch 2011 is given in this article. Of course, the same chamfered portions can also be provided at the second notch 2012 of the first electrode tab 201, the second electrode tab 202 and the notch positions of the second electrode tab 202, which will not be elaborated here.

[0082] The terms "first" and "second" in the description, claims and above-mentioned drawings of the present utility model are used to distinguish different objects, rather than to describe a specific order. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but may include steps or units that are not listed.

[0083] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A lithium ion battery, characterized in that: include: Packaging film (100); A battery cell (200), the battery cell (200) being encapsulated in the packaging film (100), the battery cell (200) comprising a first pole piece (201), a second pole piece (202), and a diaphragm (203) located between the first pole piece (201) and the second pole piece (202); The first pole piece (201) includes a first pole lug (204), and the second pole piece (202) includes a second pole lug (205); The first pole piece (201) comprises a first notch (2011), and the first pole ear (204) is located in the first notch (2011); The second pole piece (202) comprises a third notch (2021), and the second pole lug (205) is located in the third notch (2021); The diaphragm (203) is provided with a first opening (2031) and a second opening (2032) corresponding to the third notch (2021) and the first notch (2011), respectively.

2. The lithium-ion battery according to claim 1, characterized in that The battery cell (200) further comprises a first external pole lug (301) connected to the first pole lug (204) and a second external pole lug (302) connected to the second pole lug (205); At least part of the first external electrode tab (301) is located in the first notch (2011); and / or, At least a portion of the second external pole lug (302) is located in the third notch (2021).

3. The lithium-ion battery according to claim 1, characterized in that The first pole piece (201) comprises a second notch (2012), and at least a portion of the second pole lug (205) is located in the second notch (2012); and / or, The second pole piece (202) comprises a fourth notch (2022), and at least a portion of the first pole tab (204) is located in the fourth notch (2022).

4. The lithium-ion battery according to claim 3, characterized in that: The width of the fourth notch (2022) of the second pole piece (202) is smaller than the width of the first notch (2011) of the first pole piece (201); and / or, The width of the third notch (2021) of the second pole piece (202) is smaller than the width of the second notch (2012) of the first pole piece (201); and / or, The depth of the first notch (2011) of the first pole piece (201) is greater than the depth of the fourth notch (2022) of the second pole piece (202); and / or, The depth of the second notch (2012) of the first pole piece (201) is greater than the depth of the third notch (2021) of the second pole piece (202).

5. The lithium-ion battery according to claim 4, characterized in that: The difference between the width of the first notch (2011) and the width of the fourth notch (2022) is 0 to 2.0 mm; and / or, The difference between the width of the second notch (2012) and the width of the third notch (2021) is 0 to 2.0 mm; and / or, The difference between the depth of the first notch (2011) of the first pole piece (201) and the depth of the fourth notch (2022) of the second pole piece (202) is 0 to 3.0 mm; and / or, The difference between the depth of the second notch (2012) of the first pole piece (201) and the depth of the third notch (2021) of the second pole piece (202) is 0 to 3.0 mm.

6. The lithium-ion battery according to claim 5, characterized in that: The depth of the third notch (2021) and / or the fourth notch (2022) of the second pole piece (202) is D, and 0.5 mm < D < 3.0 mm.

7. The lithium ion battery according to claim 3, characterized in that: The opening depth of the diaphragm (203) is less than the depth of the third notch (2021) of the second pole piece (202).

8. The lithium-ion battery according to claim 7, characterized in that: The width of the first opening (2031) is smaller than the width of the second notch (2012) of the first pole piece (201); and / or, The width of the first opening (2031) is smaller than the width of the third notch (2021) of the second pole piece (202); and / or, The width of the second opening (2032) is smaller than the width of the first notch (2011) of the first pole piece (201); and / or, The width of the second opening (2032) is smaller than the width of the fourth notch (2022) of the second pole piece (202).

9. The lithium-ion battery according to claim 8, characterized in that: The difference between the width of the third notch (2021) and the width of the first opening (2031) is 0 to 2.0 mm; and / or, The difference between the width of the fourth notch (2022) and the width of the second opening (2032) is 0 to 2.0 mm.

10. The lithium ion battery according to claim 7, characterized in that: The side edge of the first opening (2031) is located on a side edge of the second notch (2012) of the first pole piece (201) close to the second notch (2012); and / or, The side edge of the second opening (2032) is located on a side of the side edge of the first notch (2011) of the first pole piece (201) close to the first notch (2011).

11. The lithium ion battery according to claim 1, characterized in that: First chamfered portions (206) are provided at the four corners of the first pole piece (201), a second chamfered portion (207) is provided at the top of the first notch (2011) of the first pole piece (201), and a third chamfered portion (208) is provided at the bottom of the first notch (2011) of the first pole piece (201).

12. The lithium ion battery according to claim 11, characterized in that: The radius of the second chamfered portion (207) is smaller than the radius of the first chamfered portion (206); and / or, The radius of the third chamfered portion (208) is smaller than the radius of the first chamfered portion (206).

13. The lithium ion battery according to claim 11, characterized in that: The radius of the first chamfered portion (206) is 0.5 mm to 3.0 mm; and / or, The radius of the second chamfered portion (207) is 0 to 1.5 mm; and / or, The radius of the third chamfered portion (208) is 0 to 1.5 mm.

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