A new type of lithium-ion battery

Abstract

The utility model discloses a novel lithium-ion battery, comprising a battery shell; a battery electrode group is arranged in the battery shell; a positive current collector is arranged on the top of the battery electrode group; the top of the positive current collector is connected to the bottom of the battery top cover; a negative current collector is arranged on the bottom of the battery electrode group; the negative current collector is connected to the inner side of the bottom shell plate of the battery shell; the positive current collector comprises a positive current collector metal sheet and a positive current collector metal strip; one end of the positive current collector metal sheet is connected to one end of the positive current collector metal strip; the other end of the positive current collector metal sheet is connected to the positive collector of the positive electrode sheet in the battery electrode group; the other end of the positive current collector metal strip is connected to the bottom of the battery top cover; a plurality of first arc-shaped notches are arranged around the edges of the positive current collector metal sheet; the positive current collector metal strip comprises a narrowed area segment. The positive current collector of the utility model is a highly safe current collector, which can not only ensure the electrical connection function, but also can be timely melted when the battery is short-circuited and abused, thereby ensuring the safety and reliability of the battery.

Description

Technical Field

[0001] The utility model relates to the technical field of batteries, in particular to a novel lithium ion battery. Background Art

[0002] At present, lithium-ion batteries have the advantages of high specific energy, many cycles and long storage time. They are not only widely used in portable electronic devices (such as mobile phones, digital cameras and laptops), but also widely used in large and medium-sized electric equipment such as electric vehicles, electric bicycles and electric tools. Therefore, the performance requirements for lithium-ion batteries are getting higher and higher.

[0003] In recent years, some companies have developed and produced 4680 full foil tab battery structures, which greatly reduce internal resistance, improve power, and fast charge performance. However, the design of PACK (battery pack) in the consumer field is relatively simple, and the safety and reliability requirements of the battery itself are relatively high. After using the full foil tab structure, the power performance of lithium-ion batteries has been greatly improved. However, during the external short-circuit test, because the foil tab cannot be fused in time, the battery generates too much heat, which poses a great safety hazard.

[0004] In addition, if the tab is wide, it is easy to hit the wall when bending, resulting in a short circuit (i.e., the positive current collector, which is the positive tab, contacts the battery casing connected to the negative tab and shorts out). Therefore, the design of the positive current collector of the full-foil tab battery becomes extremely critical. Utility Model Content

[0005] The purpose of the utility model is to provide a novel lithium ion battery in view of the technical defects in the prior art.

[0006] To this end, the utility model provides a novel lithium-ion battery, which includes a battery top cover, a positive electrode current collector, a battery electrode group, a negative electrode current collector and a battery shell;

[0007] A battery electrode group is arranged in the hollow battery shell;

[0008] A positive electrode current collector is provided on the top of the battery electrode group;

[0009] The top of the positive electrode current collector is connected to the bottom of the battery top cover;

[0010] A negative electrode current collector is provided at the bottom of the battery electrode group;

[0011] The negative electrode current collector is connected to the inner side of the bottom shell plate of the battery shell;

[0012] A positive electrode current collecting sheet, comprising a positive electrode current collecting metal sheet and a positive electrode current collecting metal strip;

[0013] One end of the positive electrode current collecting metal sheet is connected to one end of the positive electrode current collecting metal strip;

[0014] The other end of the positive electrode current collecting metal sheet is connected to the positive electrode current collector of the positive electrode sheet in the battery electrode group;

[0015] The other end of the positive electrode current collecting metal strip is connected to the bottom of the battery top cover;

[0016] Wherein, a plurality of first inwardly concave arc-shaped notches are evenly arranged around the edges of the positive electrode current collecting metal sheet;

[0017] A metal sheet center hole is provided at the center of the positive electrode current collecting metal sheet;

[0018] The positive electrode current collecting metal strip comprises a first trapezoidal region segment, a narrowed region segment, a second trapezoidal region segment and a rectangular region segment which are connected in sequence.

[0019] It can be seen from the technical solution provided by the above utility model that, compared with the prior art, the utility model provides a new lithium-ion battery with a scientific structural design. The positive electrode current collector serving as the positive electrode ear is a highly safe current collector, which can not only ensure the electrical connection function, but also can be blown off in time when the battery is short-circuited and abused, thereby reducing the heat generated by the battery during short-circuit abuse, effectively ensuring the safety and reliability of the battery, and having great practical significance.

[0020] For the utility model, the positive current collector includes a narrowed width region (i.e., narrowed region section) in the middle of the positive current collector metal strip, which plays a special role: when the battery is short-circuited or a short-circuit failure occurs, the region can be fused in time to avoid safety failure of the battery. At the same time, the region is easy to bend, which can effectively avoid short circuits caused by the positive electrode ear (i.e., the positive current collector) touching the shell wall of the battery shell connected to the negative electrode, thereby increasing the safety and reliability of the cylindrical foil ear lithium battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1a A schematic diagram of the structure of a novel lithium-ion battery provided by the utility model after a portion of the battery shell is cut away;

[0022] Figure 1b A three-dimensional exploded schematic diagram of the upper structure of a novel lithium-ion battery provided by the utility model;

[0023] Figure 2a A schematic structural diagram of a positive electrode current collector in a novel lithium-ion battery provided by the utility model when in an unfolded state;

[0024] Figure 2b A schematic diagram of the structure of a negative electrode current collector in a novel lithium-ion battery provided by the utility model;

[0025] Figure 2cA second structural schematic diagram of a negative electrode current collector in a novel lithium-ion battery provided by the utility model;

[0026] Figure 3 A schematic diagram of the application of a positive electrode current collector in a novel lithium-ion battery provided by the utility model;

[0027] Figure 4 A second schematic diagram of the application of a positive electrode current collector in a novel lithium-ion battery provided by the utility model;

[0028] Figure 5 The figure is a schematic diagram for comparing the battery surface temperatures of the experimental group of batteries provided by the present invention and the existing reference group of batteries in a short circuit test in Example 1. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0030] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0031] In the description of this patent, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", and "set" should be understood in a broad sense, for example, it can be fixedly connected or set, or it can be detachably connected or set, or connected or set in one piece. For ordinary technicians in this field, the specific meanings of the above terms in this patent can be understood according to specific circumstances.

[0032] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present utility model, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0033] See also Figure 1a , Figure 1b , Figure 2a to Figure 2c , Figures 3 to 5 The utility model provides a novel lithium-ion battery, comprising a battery top cover 1, a positive electrode current collector 3, a battery electrode group 4, a negative electrode current collector 5 and a battery shell 6;

[0034] A battery electrode group 4 is arranged in the hollow battery shell 6;

[0035] A positive electrode current collector 3 is provided on the top of the battery electrode group 4;

[0036] The top of the positive electrode current collector 3 is connected to the bottom of the battery top cover 1;

[0037] A negative electrode current collector 5 is provided at the bottom of the battery electrode group 4;

[0038] The negative electrode current collector 5 is connected to the inner side of the bottom shell plate of the battery shell (specifically, welded).

[0039] In the present utility model, in specific implementation, the novel lithium-ion battery is a cylindrical lithium-ion battery.

[0040] In specific implementation, the connection between the battery electrode group 4 and the positive electrode current collecting sheet 3 can be achieved by welding or riveting.

[0041] In the present utility model, in a specific implementation, the novel lithium-ion battery further includes a hollow, cylindrical positive electrode insulating sleeve cup;

[0042] The positive electrode insulating sleeve cup is located between the cylindrical battery shell 6 and the cylindrical battery pole group 4 and is used to separate the battery shell 6 from the cylindrical battery pole group 4 .

[0043] In the present utility model, in specific implementation, the top of the positive electrode current collector 3 is connected to the bottom center of the battery top cover 1 by laser welding;

[0044] The bottom of the positive electrode current collector sheet 3 is connected to the positive electrode current collector of the positive electrode sheet in the battery electrode group 4 by laser welding.

[0045] In the present invention, in specific implementation, the battery electrode group 4 includes a positive electrode sheet, a negative electrode sheet and a separator;

[0046] It should be noted that the positive electrode sheet includes a positive electrode collector and a positive electrode active material coating coated on one side or both sides of the positive electrode collector; the negative electrode sheet includes a negative electrode collector and a negative electrode active material coating coated on one side or both sides of the negative electrode collector.

[0047] The battery electrode group is a group of electrodes prepared by winding a positive electrode sheet, a negative electrode sheet and a separator;

[0048] Among them, the diaphragm is located between the positive electrode sheet and the negative electrode sheet;

[0049] The separator is used to separate the negative electrode and the positive electrode of the battery. This is a conventional design and will not be described in detail here.

[0050] In the present utility model, the specific implementation is as follows: Figure 2a As shown, the positive electrode current collecting sheet 3 includes a positive electrode current collecting metal sheet 7 and a positive electrode current collecting metal strip 10;

[0051] One end of the positive electrode current collecting metal sheet 7 is connected to one end of the positive electrode current collecting metal strip 10;

[0052] The other end of the positive electrode current collector metal sheet 7 is connected to the positive electrode collector of the positive electrode sheet in the battery electrode group 4 (for example, connected by laser welding);

[0053] The other end of the positive electrode current collecting metal strip 10 is connected to the bottom of the battery top cover 1 .

[0054] In specific implementation, the positive electrode current collecting metal sheet 7 and the positive electrode current collecting metal strip 10 are integrally formed.

[0055] In a specific implementation, a plurality of (for example, three) first inwardly concave arc-shaped notches 9 are evenly arranged around the edges of the positive electrode current collecting metal sheet 7;

[0056] A metal sheet center hole 8 is provided at the center of the positive electrode current collecting metal sheet 7;

[0057] The center hole 8 of the metal sheet is used to insert the welding needle of the battery spot welding machine located outside.

[0058] Furthermore, the diameter of the positive electrode current collecting metal sheet 7 is smaller than (specifically slightly smaller than) or equal to the diameter of the battery electrode group 4 , and can change accordingly with the change of the diameter of the battery electrode group.

[0059] It should be noted that, in order to facilitate the penetration of the electrolyte, the head of the positive electrode current collector 3 can be a special-shaped current collector with three concave arcs on the edge of a metal sheet, or a standard circular shape, but the diameter of the positive electrode current collector needs to be less than or equal to the diameter of the battery electrode group.

[0060] Furthermore, the diameter of the metal sheet center hole 8 is greater than or equal to the diameter of the vertically distributed electrode group center hole 40 at the center of the battery electrode group 4, and can be adjusted accordingly with the size of the electrode group center hole 40.

[0061] It should be noted that, since the negative electrode current collector 5 needs to be resistance welded to the bottom of the battery shell 6, in order to facilitate the insertion of the welding needle, the metal sheet at the head of the positive electrode current collector 3 (ie, the positive electrode current collector metal sheet 7) needs to have a center hole.

[0062] It should be noted that the diameter of the metal sheet center hole 8 is larger than the diameter of the electrode group center hole 40, which facilitates inserting the welding needle from the electrode group center hole for bottom welding and improves the straight-through rate of liquid injection (i.e., injecting electrolyte).

[0063] Furthermore, the maximum radius of the positive electrode current collecting metal sheet 7 is 9.3 mm;

[0064] The diameter of the center hole 8 of the metal sheet is 6 mm;

[0065] The radius of the first arc-shaped notch 9 is 8.5 mm.

[0066] In specific implementation, the positive electrode current collecting metal strip 10 includes a first trapezoidal region segment 111, a narrowed region segment 13, a second trapezoidal region segment 112 and a rectangular region segment 12 connected in sequence;

[0067] The narrowed region segment 13 is located between the first trapezoidal region segment 111 and the second trapezoidal region segment 112;

[0068] Furthermore, the first trapezoidal region segment 111 and the second trapezoidal region segment 112 are axially symmetrically distributed.

[0069] Furthermore, the width of the narrowed region segment 13 is smaller than the widths of the first trapezoidal region segment 111 , the second trapezoidal region segment 112 , and the rectangular region segment 12 ;

[0070] The thickness of the narrowed region segment 13 is equal to the thickness of the first trapezoidal region segment 111 , the second trapezoidal region segment 112 , and the rectangular region segment 12 ;

[0071] Furthermore, as the distance from the narrowing region 13 gradually decreases, the widths of the first trapezoidal region 111 and the second trapezoidal region 112 gradually decrease.

[0072] It should be noted that there is a narrowed area (i.e., narrowed area 13) in the middle of the positive electrode current collecting metal strip 10. The main purpose of the design of this area is that when the battery is short-circuited or a short-circuit fault occurs, this area can be blown in time to avoid safety failure of the battery. At the same time, this area is easy to bend, which can effectively avoid short circuit caused by the positive electrode ear (i.e., the positive electrode current collecting sheet 3) touching the shell wall of the battery shell 6 connected to the negative electrode, thereby increasing the safety and reliability of the cylindrical foil ear lithium battery.

[0073] It should be noted that the first trapezoidal region segment 111 , the second trapezoidal region segment 112 , the narrowed region segment 13 and the rectangular region segment 12 are made of the same material.

[0074] Furthermore, the total length of the positive electrode current collecting metal strip 10 is 17.5 mm, and the maximum width is 6 mm;

[0075] The length of the narrowed region 13 is 2.5 mm;

[0076] The length of the first trapezoidal region 111 (including the trapezoidal region portion between the connection with the positive electrode current collecting metal sheet and the narrowing position of the metal strip) is 5 mm;

[0077] The first trapezoidal region segment 111 and the second trapezoidal region segment 112 have the same length;

[0078] The length of the rectangular area section 12 is 5 mm.

[0079] In specific implementation, Figure 3 As shown, the positive electrode current collector metal sheet 7 of the positive electrode current collector sheet 3 is welded to the battery electrode group 4 (specifically, to the positive electrode current collector of the positive electrode sheet in the battery electrode group 4);

[0080] The rectangular region 12 of the positive current collecting metal strip 10 of the positive current collecting sheet 3 is connected to the battery top cover 1 .

[0081] Furthermore, the rectangular region 12 of the positive current collecting metal strip 10 of the positive current collecting sheet 3 is connected to the bottom center of the battery top cover 1 (for example, by welding, specifically by laser welding).

[0082] For specific implementation, see Figure 4 As shown, the center hole 8 of the metal sheet of the positive electrode current collector 3 is the insertion position of the welding needle of the battery spot welding machine;

[0083] The welding needle of the battery spot welding machine is connected to the top center point of the negative electrode current collector 5, and is used to weld the negative electrode current collector 5 to the bottom of the battery shell 6 (specifically resistance welding). In addition, because the negative electrode current collector 5 does not need to be fused, the negative electrode current collector 5 only needs to include a metal sheet area (that is, a metal sheet area with the same shape as the positive electrode current collector metal sheet 7, but without a center hole), and does not have and does not need a positive electrode current collector metal strip area like the positive electrode current sheet 3.

[0084] In a specific implementation, the top of the negative electrode current collector sheet 5 and the negative electrode current collector of the negative electrode sheet in the battery electrode group 4 are laser welded.

[0085] For specific implementation, see Figure 1a , Figure 2b , Figure 2c As shown, a rectangular battery shell welding portion 51 is provided at the center of the negative electrode current collector 5;

[0086] Furthermore, a plurality of upwardly protruding bumps (i.e., pits) may be distributed on the battery housing welding portion 5, which is beneficial to increase the welding area.

[0087] In specific implementation, three spaced-apart battery electrode group welding sections 53 (i.e., docking blocks) are arranged around the negative electrode current collector 5.

[0088] There is a second concave arc-shaped notch 52 between any two adjacent butted battery pole group welding sections 53 .

[0089] In a specific implementation, the negative electrode current collector 5 is made of copper.

[0090] In the present invention, in a specific implementation, the battery top cover 1 and the battery shell 6 are connected by roller groove sealing. From then on, the various parts of the above-mentioned utility model cooperate with each other to form a cylindrical foil tab lithium-ion battery with a high-safety positive electrode collector.

[0091] In order to more clearly understand the technical solution of the utility model, the working principle of the utility model is explained below.

[0092] Given that the positive electrode busbars of most current cylindrical lithium-ion foil tab batteries are made of overly thick positive electrode busbars, when the lithium battery is short-circuited and abused, the overly thick positive electrode busbars will pass a larger current without melting, causing the battery temperature to rise sharply. When the temperature exceeds a certain range, it may cause dangerous accidents such as battery explosion and fire.

[0093] In order to solve this technical problem, the positive current collecting metal strip 10 of the positive current collecting sheet in the utility model has a narrowed area in the middle so that it can be melted when short-circuited and abused, thereby protecting the battery and preventing safety accidents.

[0094] Because the positive electrode potential of the lithium battery is relatively high, common metals will undergo oxidation reactions under the positive electrode voltage of the lithium battery, and aluminum can form a passivation film in the electrolyte to prevent it from undergoing oxidation reactions, so the material of the positive electrode current collector 3 is metal aluminum.

[0095] In order to more clearly understand the technical solution of the present invention, the present invention is described below in conjunction with embodiments.

[0096] Embodiment 1

[0097] Will Figure 2a The positive electrode current collector 3 shown is used to prepare a 21700-type foil-ear cylindrical lithium-ion battery. The positive electrode current collector of the reference group battery (i.e., an existing traditional 21700-type foil-ear cylindrical battery) has no narrowed area (i.e., it is just an ordinary rectangular metal sheet). Both batteries are placed in a 25°C test room for testing.

[0098] like Figure 5 As shown, the maximum surface temperature of the battery in the reference group is close to 85°C when a short circuit occurs (for example, a 5mΩ short circuit), which exceeds the decomposition temperature of the lithium salt and poses a risk of fire and explosion. However, the lithium-ion battery using the high-safety positive electrode current collector 3 provided by the utility model has a maximum surface temperature of only about 35°C when a short circuit occurs (for example, a 5mΩ short circuit). During disassembly, it was found that the high-safety positive electrode current collector using the utility model was melted at the narrowest point. This shows that the application of the high-safety positive electrode current collector 3 can effectively reduce the external short circuit time of the battery, thereby reducing heat generation and improving the safety of the experimental cylindrical lithium-ion battery under specific conditions.

[0099] In summary, compared with the prior art, the new lithium-ion battery provided by the present invention is a cylindrical foil-earthed lithium-ion battery with a high-safety positive electrode current collector, which can avoid the safety risks caused by short-circuit abuse, is beneficial to improving the safety and reliability of cylindrical foil-earthed batteries, and has important production practice significance.

[0100] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A novel lithium-ion battery, characterized in that: It comprises a battery top cover (1), a positive electrode current collector (3), a battery electrode group (4), a negative electrode current collector (5) and a battery shell (6); A battery electrode group (4) is arranged in the hollow battery shell (6); A positive electrode current collecting sheet (3) is arranged on the top of the battery electrode group (4); The top of the positive electrode current collector (3) is connected to the bottom of the battery top cover (1); A negative electrode current collecting sheet (5) is arranged at the bottom of the battery electrode group (4); The negative electrode current collector (5) is connected to the inner side of the bottom shell plate of the battery shell; A positive electrode current collecting sheet (3), comprising a positive electrode current collecting metal sheet (7) and a positive electrode current collecting metal strip (10); One end of the positive electrode current collecting metal sheet (7) is connected to one end of the positive electrode current collecting metal strip (10); The other end of the positive electrode current collecting metal sheet (7) is connected to the positive electrode current collector of the positive electrode sheet in the battery electrode group (4); The other end of the positive electrode current collecting metal strip (10) is connected to the bottom of the battery top cover (1); Wherein, a plurality of first inwardly concave arc-shaped notches (9) are evenly arranged on the edges of the positive electrode current collecting metal sheet (7); A metal sheet center hole (8) is provided at the center of the positive electrode current collecting metal sheet (7); The positive electrode current collecting metal strip (10) comprises a first trapezoidal region segment (111), a narrowed region segment (13), a second trapezoidal region segment (112) and a rectangular region segment (12) which are connected in sequence.

2. The novel lithium-ion battery according to claim 1, characterized in that: The novel lithium-ion battery is a cylindrical lithium-ion battery.

3. The novel lithium-ion battery according to claim 1, characterized in that: The top of the positive electrode current collector (3) is connected to the bottom center of the battery top cover (1) by laser welding; The bottom of the positive electrode current collector sheet (3) is connected to the positive electrode current collector of the positive electrode sheet in the battery electrode group (4) by laser welding.

4. The novel lithium-ion battery according to claim 1, characterized in that: The diameter of the positive electrode current collecting metal sheet (7) is less than or equal to the diameter of the battery electrode group (4); and / or, The diameter of the central hole (8) of the metal sheet is greater than or equal to the diameter of the vertically distributed electrode group central hole (40) at the center position of the battery electrode group (4).

5. The novel lithium-ion battery according to claim 1, characterized in that: The maximum radius of the positive electrode current collecting metal sheet (7) is 9.3 mm; The diameter of the center hole (8) of the metal sheet is 6 mm; The radius of the first arc-shaped notch (9) is 8.5 mm.

6. The novel lithium-ion battery according to claim 1, characterized in that: The first trapezoidal region segment (111) and the second trapezoidal region segment (112) are axially symmetrically distributed; and / or, The width of the narrowed region (13) is smaller than the widths of the first trapezoidal region (111), the second trapezoidal region (112) and the rectangular region (12); and / or, As the distance from the narrowing region (13) gradually decreases, the widths of the first trapezoidal region (111) and the second trapezoidal region (112) gradually decrease.

7. The novel lithium-ion battery according to claim 1, characterized in that: The total length of the positive electrode current collecting metal strip (10) is 17.5 mm; Wherein, the length of the narrowed region segment (13) is 2.5 mm; The length of the first trapezoidal region (111) is 5 mm; The first trapezoidal region segment (111) and the second trapezoidal region segment (112) have the same length; The length of the rectangular area segment (12) is 5 mm.

8. The novel lithium-ion battery according to claim 1, characterized in that: The rectangular area segment (12) in the positive electrode current collecting metal strip (10) of the positive electrode current collecting sheet (3) is laser welded to the bottom center position of the battery top cover (1); and / or, The positive electrode current collecting metal sheet (7) and the positive electrode current collecting metal strip (10) are integrally formed.

9. The novel lithium-ion battery according to any one of claims 1 to 8, characterized in that: A rectangular battery housing welding portion (51) is provided at the center of the negative electrode current collector (5); Three spaced-apart butting battery pole group welding sections (53) are arranged around the negative electrode current collector (5); There is a second inwardly concave arc-shaped notch (52) between any two adjacent butted battery pole group welding sections (53).

10. The novel lithium-ion battery according to any one of claims 1 to 8, characterized in that: Also included is a hollow, cylindrical positive electrode insulating sleeve cup; The positive electrode insulating sleeve cup is located between the cylindrical battery shell (6) and the cylindrical battery electrode group (4) and is used to separate the battery shell (6) from the cylindrical battery electrode group (4).

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