Battery

Abstract

The present invention discloses a battery comprising a housing, a connecting piece, and a battery cell. The housing is provided with an electrode terminal. The connecting piece is disposed within the housing and electrically connected to the electrode terminal. The battery cell is disposed within the housing. The battery cell comprises a battery cell body and a negative electrode tab. The battery cell body comprises a negative electrode tab extending from one side of the battery cell body. The connecting piece is spaced apart from and opposite to the side of the battery cell body provided with the negative electrode tab. The end of the negative electrode tab remote from the battery cell body is electrically connected to the connecting piece. The negative electrode tab comprises a negative electrode active material layer and a current collector. The battery cell body has a thickness of D mm, and the minimum distance between the connecting piece and the negative electrode active material layer within the battery cell body is H mm, with 1.5 ≤ D / H ≤ 80. The present invention ensures the energy density of the battery while making it less susceptible to material shedding.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to a battery. Background Art

[0002] At present, lithium-ion batteries include a shell, a cover, a battery cell and an adapter. The cover is installed on the shell, and a pole is provided on the cover. The adapter and the battery cell are both located in the shell, and the adapter is connected to the pole, and the tab extends from the side of the battery cell.

[0003] During the battery manufacturing process, the adapter plate will be welded together with the tab, which will easily squeeze the tab and then squeeze the electrode of the battery cell. At the same time, since the negative electrode of the battery cell is closer to the adapter plate than the positive electrode, when the tab is squeezed, the negative electrode is easily squeezed and the active material layer on the negative electrode falls off. Summary of the Invention

[0004] The purpose of the present invention is to provide a battery to prevent the active material layer on the negative electrode sheet from falling off.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0006] A battery having a first direction, a second direction, and a third direction perpendicular to each other, comprising:

[0007] a housing, wherein the housing is provided with electrode terminals;

[0008] a connecting piece, which is disposed in the housing and electrically connected to the electrode terminal;

[0009] A battery cell is disposed in the housing, the battery cell comprising a battery cell body and a negative electrode tab, the battery cell body comprising a negative electrode sheet, the negative electrode tab extending from one side of the battery cell body, the connecting sheet being opposite to and spaced from the side of the battery cell body where the negative electrode tab is provided, the negative electrode tab being electrically connected to the connecting sheet at one end away from the battery cell body, and the negative electrode sheet comprising a negative electrode active material layer and a current collector;

[0010] The thickness of the battery cell body in the first direction is D mm, and the minimum distance between the connecting piece and the negative electrode active material layer in the battery cell body in the direction perpendicular to the side of the battery cell body on which the negative electrode ear is provided is H mm, and 1.5≤D / H≤80.

[0011] Compared with the prior art, the battery according to the embodiment of the present invention has the following advantages:

[0012] In the present invention, by comprehensively controlling the relationship between the thickness D of the battery cell body and the minimum distance H between the negative electrode active material layer in the battery cell body, the thickness of the battery cell body and the distance between the connecting sheet and the negative electrode active material layer in the battery cell body are balanced, thereby avoiding damage to the negative electrode sheet by the connecting sheet, thereby preventing the negative electrode sheet from falling off, while taking into account the energy density of the battery; it also avoids excessive pressure causing the tab to be inserted upside down, thereby increasing the risk of battery short circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a three-dimensional diagram of the overall structure of an embodiment of the present invention;

[0014] Figure 2 It is an exploded view of the overall structure of an embodiment of the present invention;

[0015] Figure 3 is a schematic diagram of a battery cell and a connecting piece according to an embodiment of the present invention;

[0016] Figure 4 yes Figure 3 A magnified view of point A in the figure;

[0017] Figure 5 Schematic diagram of the tab and the connecting piece of an embodiment of the present invention;

[0018] Figure 6 Schematic diagram of the dimensions between the tab and the connecting piece according to an embodiment of the present invention;

[0019] Figure 7 Schematic diagram of a connecting piece and a battery cell according to an embodiment of the present invention.

[0020] In the figure,

[0021] 1. Housing; 11. Electrode terminal;

[0022] 2. Connecting piece; 21. First connecting portion; 22. Second connecting portion;

[0023] 3. Battery cell; 31. Battery cell body; 32. Negative electrode ear; 321. Sub-negative electrode ear; 322. Arc-shaped portion; 33. Negative electrode active material layer; 4. Cover. DETAILED DESCRIPTION

[0024] The following embodiments of the present invention are described in further detail with reference to the accompanying drawings and examples. The following examples are used to illustrate the present invention but are not intended to limit the scope of the present invention.

[0025] In the description of the present invention, it should be understood that the term "comprising" as used in the present specification refers to the presence of the stated features, integers, steps, operations, parts / components, and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, parts / components, components, and / or groups thereof. It should be understood that when we refer to a part / component as being "connected" to another part / component, it can be directly connected to the other part / component, or there can be intermediate parts / components. The term "and / or" as used herein includes all or any one of the associated listed items and all combinations thereof.

[0026] like Figures 1 to 7 As shown, the present invention relates to a battery having a first direction, a second direction, and a third direction intersecting perpendicularly to each other. The battery comprises a housing 1, a connecting tab 2, and a battery cell 3. The housing 1 is provided with an electrode terminal 11. The connecting tab 2 is disposed within the housing 1 and electrically connected to the electrode terminal 11. The battery cell 3 is disposed within the housing 1 and comprises a battery body 31 and a negative electrode tab 32. The battery body 31 includes a negative electrode tab. The negative electrode tab 32 extends from one side of the battery body 31. The connecting tab 2 is spaced apart from and opposite to the side of the battery body 31 where the negative electrode tab 32 is provided. The negative electrode tab 32 is electrically connected to the connecting tab 2 at one end away from the battery body 31. The negative electrode tab includes a negative active material layer 33 and a current collector. The first, second, and third directions are the width, length, and height directions of the housing, respectively.

[0027] The thickness of the battery cell body 31 in the width direction of the housing 1 is D mm. The minimum distance between the connecting piece 2 and the negative electrode active material layer 33 in the battery cell body 31 in a direction perpendicular to the side of the battery cell body 31 on which the negative electrode tab 32 is provided is H mm, and 1.5 ≤ D / H ≤ 80. The value of D / H can also be 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, or 75.

[0028] In the present invention, by comprehensively controlling the relationship between the thickness D of the battery cell body 31 and the minimum distance H between the negative electrode active material layer 33 in the battery cell body 31, the thickness of the battery cell body 31 and the distance between the connecting piece 2 and the negative electrode active material layer 33 in the battery cell body 31 are balanced, and 1.5≤D / H≤80 is maintained. This can prevent the force from being transmitted to the negative electrode sheet through the tab when the connecting piece 2 and the tab are welded, thereby damaging the negative electrode sheet and causing the negative electrode sheet to fall off, while taking into account the energy density of the battery; furthermore, D / H cannot be too small, otherwise the thickness of the battery cell body 31 will be too large. If the D / H is too small, the distance between the connecting piece 2 and the negative active material layer 33 in the battery cell body 31 will be too large, resulting in less active material to actually exert the battery capacity, resulting in low energy density of the battery; D / H cannot be too large, otherwise the thickness of the battery cell body 31 will be too large, the demand for overcurrent energy will increase, and the number of negative ears 32 led out of the battery cell body 31 will increase. If the distance between the connecting piece 2 and the negative active material layer 33 in the battery cell body 31 is too small, then after the connecting piece 2 and the negative ear 32 are welded, the pressure will easily be transmitted to the negative electrode sheet, resulting in an increased risk of the negative active material layer 33 on the negative electrode sheet falling off.

[0029] It should be explained that the shell 1, specifically, the shell 1 is arranged on the outermost side of the battery cell 3, and is used to protect the battery cell 3; the material of the shell 1 can be selected from but not limited to aluminum alloy, steel, etc.; specifically, it can be aluminum-manganese alloy, aluminum-magnesium alloy, stainless steel, nickel-plated steel, etc.

[0030] The connecting piece 2 is used to realize current transmission and electrically connect the tab and the electrode terminal 11. The material of the connecting piece 2 can be aluminum, copper, etc.

[0031] The electrode terminal 11 serves as the battery current output terminal, and is used to connect to an external busbar, etc., to achieve series and parallel connection between batteries. The electrode terminal 11 may include a positive electrode terminal and a negative electrode terminal. The material of the electrode terminal 11 may be aluminum, copper, or a copper-aluminum composite.

[0032] The tabs serve as the current output terminals within the battery cell 3 and are electrically connected to the electrode terminals 11 and the like. The tabs can be cut from the current collector or formed as separate metal parts. It is understood that the positive tab 34 is electrically connected to the positive electrode sheet in the battery cell 3, and the negative tab 32 is electrically connected to the negative electrode sheet in the battery cell 3.

[0033] The battery cell 3 includes a positive electrode sheet, a negative electrode sheet, and a separator. The separator is positioned between the positive and negative electrode sheets. The positive, negative, and separator sheets are stacked to form the battery cell 3. The positive electrode sheet includes a positive current collector and a positive active material layer, while the negative electrode sheet includes a negative current collector and a negative active material layer 33. The positive current collector is not particularly limited, as long as it is conductive and does not cause adverse chemical changes in the battery. Materials such as stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel surface-treated with carbon, nickel, titanium, or silver can be used. The negative current collector can be made of copper, stainless steel, nickel, titanium, or the like. In specific embodiments, aluminum can be used for the positive electrode, and copper can be used for the negative electrode. The positive active material layer includes a positive electrode active material, such as a nickel-cobalt-manganese ternary material, lithium iron phosphate, or lithium iron manganese phosphate. The negative active material layer 33 includes a negative electrode active material, such as artificial graphite, natural graphite, or a silicon-based material.

[0034] In some embodiments, 5≤D / H≤70.

[0035] By further controlling 5≤D / H≤70, the risk of the negative electrode active material layer 33 being lost due to the connecting sheet 2 can be further reduced while taking into account the battery energy density.

[0036] In some embodiments, 10 mm ≤ D ≤ 75 mm. The value of D may also be 15 mm, 20 mm, 25 mm, 30 mm, 35 mm, 40 mm, 45 mm, 50 mm, 55 mm, 60 mm, 65 mm, or 70 mm.

[0037] By controlling the thickness range of the battery cell body 31 , the battery energy density is improved, while the subsequent contact with the connecting sheet 2 is reduced, thereby reducing the risk of the negative electrode sheet falling off.

[0038] In some embodiments, 1 mm ≤ H ≤ 8 mm. The value of H may also be 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, or 7 mm.

[0039] By controlling the distance H between the connecting piece 2 and the negative electrode active material layer 33 in the battery cell body 31, it is possible to avoid H being too large, resulting in low space utilization in the shell 1 and low battery energy density; it is also possible to avoid H being too small, resulting in greater pressure on the negative electrode sheet by the connecting piece 2, increasing the risk of the negative electrode sheet falling off.

[0040] In some embodiments, the battery cell 3 is provided with a height of 1 mm ≤ H ≤ 6 mm.

[0041] When only one battery cell 3 is provided in the shell 1 of the battery, after the negative electrode ear 32 of the battery cell 3 is welded to the connecting sheet 2, the risk of squeezing the negative electrode sheet of the battery cell 3 is small, so that 1mm≤H≤6mm can be maintained to prevent the battery from falling off and ensure the energy density of the battery.

[0042] In some embodiments, there are at least two battery cells 3, with 2 mm ≤ H ≤ 8 mm.

[0043] When at least two battery cells 3 are arranged in the shell 1 of the battery, there is a high risk of squeezing the negative electrode sheet of the battery cell 3 after the negative electrode ear 32 of the battery cell 3 in the shell 1 is welded to the connecting sheet 2. Therefore, by maintaining 2mm≤H≤8mm, the energy density of the battery is ensured while preventing the battery from falling off.

[0044] In some embodiments, the connecting piece 2 and the side surface of the battery cell body 31 in the longitudinal direction of the shell 1 are opposite and spaced apart, and the negative electrode ear 32 extends from the side surface of the battery cell body 31 in the longitudinal direction of the shell 1 and is electrically connected to the connecting piece 2. The shell 1 is provided with the electrode terminal 11 on one side in the height direction. In the height direction of the shell 1, the distance between the end of the negative electrode ear 32 close to the electrode terminal 11 and the electrode terminal 11 is h1mm, and the distance between the end of the connecting piece 2 close to the electrode terminal 11 and the electrode terminal 11 is h2mm, wherein h2

[0045] That is, the end of the connecting piece 2 close to the electrode terminal 11 protrudes beyond the end of the negative ear 32 close to the electrode terminal 11, so that after the negative ear 32 is welded to the connecting piece 2, the size of the negative ear 32 that can be electrically connected to the connecting piece 2 becomes smaller, avoiding further impact on the overcurrent capacity of the negative ear 32.

[0046] In some embodiments, 1 mm ≤ h1 - h2 ≤ 8 mm is maintained. The value of h1 - h2 may also be 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, or 7 mm.

[0047] Specifically, the difference between h1 and h2 cannot be too small, otherwise the negative electrode tab 32 will be closer to the edge of the cell body 31 in the third direction. The edge of the negative electrode sheet itself is at a relatively high risk of material dropout due to its edge position. If the connecting piece 2 also applies force to the negative electrode sheet, the risk of material dropout of the negative active material layer 33 at the edge of the negative electrode sheet will be even greater. At the same time, the difference between h1 and h2 cannot be too large, otherwise the connecting piece 2 will leave a small weldable area for the negative electrode tab 32, affecting the battery's current capacity. Therefore, it is recommended to maintain 1mm ≤ h1 - h2 ≤ 8mm to reduce the risk of material dropout while ensuring current capacity.

[0048] ​In some embodiments, the negative electrode tab 32 extends from a side surface of the battery cell body 31 in the longitudinal direction of the housing 1 and is electrically connected to the connecting tab 2. The negative electrode tab 32 has a dimension a mm in the height direction of the housing 1, and the connecting tab 2 has a dimension cm in the height direction of the housing 1, where a>c, 0.15≤c / a≤0.75. The value of c / a can also be 0.2, 0.3, 0.4, 0.5, 0.55, 0.6, 0.65, or 0.7.

[0049] That is, the dimension of the connecting piece 2 in the height direction of the shell 1 is smaller than the dimension of the negative electrode ear 32 in the height direction of the shell 1, the relative area of ​​the connecting piece 2 and the negative electrode ear 32 is small, and the area causing pressure on the negative electrode ear 32 is small, so as to further avoid the pressure of the connecting piece 2 being transmitted to the negative electrode ear 32, and then transmitted to the negative electrode active material layer 33 of the negative electrode sheet, causing the negative electrode active material layer 33 to fall off; at the same time, the relative area of ​​the connecting piece 2 and the negative electrode ear 32 cannot be too small, otherwise it will affect the welding area of ​​the connecting piece 2 and the negative electrode ear 32, affect the overcurrent capacity of the battery, and easily cause the battery temperature to rise.

[0050] In some embodiments, the thickness of the connecting piece 2 is T1 mm, 0.2 mm ≤ T1 ≤ 3 mm, and / or the hardness of the connecting piece 2 is 20-150 HB. The value of T1 can also be 0.5 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, or 2.8 mm. The Brinell hardness of the connecting piece 2 can be 30 HB, 50 HB, 70 HB, 90 HB, 110 HB, 130 HB, or 140 HB.

[0051] By controlling the thickness of 0.2mm≤T1≤3mm, the thickness of the connecting piece 2 is prevented from being too thick, which would put great pressure on the negative electrode sheet and increase the risk of the negative electrode sheet dropping. It is also prevented from being too thick, which would occupy the internal space of the housing 1 and cause low battery energy density. It is also prevented from being too thin, which would lead to poor flow capacity and increased battery temperature rise. Similarly, by controlling the hardness of the connecting piece 2 to 20-150HB, it is possible to avoid the connecting piece 2 colliding with the negative electrode sheet in the battery cell body 31, which would cause a large impact on the negative electrode sheet and increase the risk of the negative active material layer 33 on the negative electrode sheet dropping.

[0052] In some embodiments, the width of the connecting piece 2 is W mm, 5 mm ≤ W ≤ 68 mm. The value of W can also be 10 mm, 15 mm, 20 mm, 25 mm, 30 mm, 35 mm, 40 mm, 45 mm, 50 mm, 55 mm, 60 mm or 65 mm.

[0053] By controlling the width of the connecting piece 2 within the range of 5-68 mm, the overcurrent and the impact on the negative electrode sheet are balanced to avoid the connecting piece 2 being too small in width, resulting in a small area for subsequent welding of the connecting piece 2 with the negative electrode ear 32, affecting the overcurrent capacity and increasing the temperature rise of the battery; and also avoiding the connecting piece 2 being too large in width, resulting in a large area relative to the negative electrode ear 32, which will subsequently cause a large area of ​​pressure on the negative electrode sheet and a high risk of the negative electrode sheet falling off.

[0054] In some embodiments, the battery cells 3 are provided with at least two, and in the length direction of the shell 1, the connecting piece 2 and the side of the battery body 31 of each battery cell 3 where the negative electrode ear 32 is provided have an overlapping area, and the negative electrode ear 32 of each battery cell 3 is connected to the side of the connecting piece 2 facing away from the battery cell 3, wherein 2mm≤H≤7.5mm.

[0055] When there are at least two battery cells 3, the connecting piece 2 also covers all the battery cells 3 in the shell 1 in the length direction of the shell 1. At the same time, more negative tabs 32 are led out from the battery cells 3, so that more negative tabs 32 are welded on the connecting piece 2. By further controlling H within the range of 2-7.5mm, the risk of battery material loss can be further reduced.

[0056] In some embodiments, the cell body 31 includes a stacked separator and a negative electrode sheet. A negative electrode tab 32 extends outward from one side of the negative electrode sheet. The connecting sheet 2 is spaced apart from and opposite the side of the negative electrode sheet where the negative electrode tab 32 is located. The separator is used to insulate the positive and negative electrode sheets to prevent short circuits between the positive and negative electrodes. The separator is made of PP or PE, for example.

[0057] The distance between the negative electrode sheet and the connecting sheet 2 is L1 mm, and the distance between the separator and the connecting sheet 2 is L2 mm, wherein L1>L2, 0.5 mm≤L1-L2≤5 mm. The value of L1-L2 can also be 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, or 4.5 mm.

[0058] That is, maintaining 0.5mm≤L1-L2≤5mm, the diaphragm is closer to the connecting piece 2 than the negative electrode sheet, and the side of the diaphragm close to the connecting piece 2 exceeds the side of the negative electrode sheet close to the connecting piece 2. Therefore, when the connecting piece 2 approaches the negative electrode sheet, the diaphragm can also act as a buffer between the two, reducing the impact of the connecting piece 2 on the negative electrode sheet and reducing the risk of battery material loss. At the same time, L1-L2 cannot be too small, otherwise it will easily weaken the diaphragm's ability to act as a buffer and cannot fully avoid the impact of the connecting piece 2 on the negative electrode sheet. L1-L2 cannot be too large, otherwise the diaphragm will be redundant and affect the heat dissipation of the battery cell 3.

[0059] Preferably, 1 mm ≤ L1 - L2 ≤ 3.5 mm, so as to further improve the buffering effect and reduce the influence of the connecting sheet 2 on the negative electrode sheet.

[0060] In some embodiments, the thickness of the negative electrode active material layer 33 is T2 mm, wherein T2 ≥ 0.06 mm, and 1.8 mm ≤ H ≤ 7 mm.

[0061] Specifically, negative electrode active material layers 33 are provided on the current collectors on both sides of the negative electrode sheet, so T2 refers to the thickness of the negative electrode active material layers 33 on both sides of the negative electrode sheet. When T2 ≥ 0.06 mm, the risk of the negative electrode active material layers 33 dropping is high. By further controlling H within the range of 1.8-7 mm, the impact of the connecting sheet 2 on the negative electrode sheet can be further reduced, thereby preventing the negative electrode sheet from dropping.

[0062] Preferably, 0.06mm≤T2≤2.5mm, and the value of T2 can also be 0.1mm, 0.5mm, 0.7mm, 1mm, 1.2mm, 1.5mm, 1.8mm, 2mm, 2.2mm, or 2.4mm. Furthermore, 0.08mm≤T2≤2mm. This further reduces the impact of the connecting piece 2 on the negative electrode sheet and prevents the negative electrode sheet from falling off.

[0063] In some embodiments, the battery cell 3 is a laminated battery cell, wherein 20≤D / H≤75.

[0064] The laminated battery cell includes positive and negative electrodes, and a separator. Adjacent positive and negative electrodes are arranged discontinuously, while the separator can be continuous. For example, in a Z-shaped laminated cell, the separator can also be arranged discontinuously. The stacking of the positive, negative, and separators in the laminated battery cell is relatively loose. After the negative electrode tab 32 is extended from the cell body 31, the stacking of the multiple layers of negative electrode tabs 321 is also relatively loose. The negative active material layers 33 on the multiple negative electrode tabs are less subject to internal pressure. By controlling the D / H ratio within the range of 20-75, the battery energy density can be increased while minimizing the risk of battery material dropout.

[0065] In some embodiments, the battery cell 3 is a wound battery cell, wherein 12≤D / H≤70.

[0066] The wound battery cell is formed by winding the positive electrode sheet, the negative electrode sheet and the separator. The adjacent positive electrode sheets, the adjacent negative electrode sheets and the adjacent separators are continuously arranged. The positive electrode sheets, the negative electrode sheets and the separators are stacked relatively compactly, and the multi-layer sub-negative electrode ears 321 are also stacked relatively compactly. The negative electrode active material layer 33 on the negative electrode sheet is subjected to high internal pressure after winding, which increases the risk of battery material falling off. By controlling D / H within the range of 12-70, the risk of the negative electrode sheet falling off after being subjected to the pressure of the connecting sheet 2 can be reduced, while avoiding the battery's energy density being too low.

[0067] In some embodiments, the negative electrode tab includes a tab connection portion and a cell body connection portion, respectively connected to the connecting tab and the cell body. The negative electrode tab 32 includes multiple sub-negative tabs 321. In the width direction of the housing 1, the cell body 31 includes a first side and a second side facing away from each other. The multiple sub-negative tabs 321 are gathered from the first side to the second side and then bent around the connecting tab 2 to connect to the side of the connecting tab 2 facing away from the cell body 31. After the multiple sub-negative tabs 321 are gathered, an arcuate portion 322 is formed between the cell body connection portion and the first side. The connecting tab 2 is at least partially disposed opposite the arcuate portion 322. The size of the arcuate portion 322 is R mm, where 0.5 mm ≤ R ≤ 5 mm. The value of R can also be 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, or 4.5 mm.

[0068] That is, after the multiple sub-negative tabs 321 are folded together, an arc portion 322 will be formed between the connecting portion of the battery cell body and the first side. The existence of the arc portion 322 will increase the risk of the connecting piece 2 affecting the negative electrode sheet. Therefore, by controlling R between 0.5-5mm, the arc portion 322 can be avoided from being too large to reduce the influence of the connecting piece 2, thereby reducing the risk of material falling off on the negative electrode sheet; at the same time, it can also avoid the arc portion 322 being too small. If the arc portion 322 is too small, the negative tab 32 will be too close to the battery cell body 31, which will cause the negative tab 32 to crush the negative electrode sheet of the battery cell body 31, and will also cause the negative tab 32 to easily break.

[0069] Preferably, R ≥ 0.5 mm, and 2.5 mm ≤ H ≤ 7.5 mm.

[0070] When R ≥ 0.5 mm, in order to reduce the risk of battery dropout, H needs to be kept within the range of 2.5-7.5 mm.

[0071] In some embodiments, the length of the negative electrode tab 32 extending from one side of the cell body 31 is M mm, where 10 mm ≤ M ≤ 40 mm. The value of M can also be 15 mm, 20 mm, 25 mm, 30 mm, 35 mm, or 38 mm.

[0072] Preferably, 15mm≤M≤35mm.

[0073] When H is too large, the risk of battery material falling off is low. However, the distance between the battery cell body 31 and the connecting piece 2 will also increase. By controlling the length M of the negative electrode ear 32, insufficient welding area between the negative electrode ear 32 and the connecting piece 2 can be avoided, resulting in insufficient battery overcurrent capacity.

[0074] It should be noted that when measuring the length M of the negative electrode tab 32 extending from one side of the battery body 31, the negative electrode tab 32 can be straightened and then measured, and a soft ruler can be used for measurement, or a measuring line can be used to compare the length of the negative electrode tab 32 and then measure the length of the measuring line.

[0075] In some embodiments, the cell body 31 includes a plurality of negative electrode sheets, each of which has a sub-negative electrode tab 321 extending outward, and all of the sub-negative electrode tabs 321 form the negative electrode tab 32 , wherein 1.8 mm ≤ H ≤ 7 mm.

[0076] The multiple negative electrode sheets of the battery cell body 31 all have sub-negative electrode ears 321 extending outward. The multiple sub-negative electrode ears 321 are stacked together to form the negative electrode ear 32, thereby ensuring the battery's overflow capacity. However, the thickness of the negative electrode ear 32 is also relatively large. By further controlling H within the range of 1.8-7mm, the negative electrode sheet can be further prevented from falling off.

[0077] In some embodiments, the cell body 31 includes a plurality of negative electrode sheets, some of the negative electrode sheets have sub-negative electrode tabs 321 extending outward, and all the sub-negative electrode tabs 321 form the negative electrode tab 32 , wherein 1.2 mm ≤ H ≤ 4 mm.

[0078] Among the multiple negative electrode sheets of the battery cell body 31, some of the negative electrode sheets have sub-negative electrode ears 321 extending outward, while the remaining negative electrode sheets are not provided with sub-negative electrode ears 321. All the existing sub-negative electrode ears 321 are stacked together to form the negative electrode ear 32, so the thickness of the negative electrode ear 32 is not too large and is easy to bend. By further controlling H within the range of 1.2-4mm, the connecting sheet 2 can be further prevented from squeezing the negative electrode ear 32 and causing material falling.

[0079] In some embodiments, the shell 1 has an opening on at least one side in the height direction, the opening cover is provided with a cover body 4, the electrode terminal 11 is provided on the cover body 4, the connecting piece 2 is L-shaped, the connecting piece 2 includes a first connecting portion 21 and a second connecting portion 22, and there is an angle between the first connecting portion 21 and the second connecting portion 22, the angle range is 80°-110°, the first connecting portion 21 is electrically connected to the negative electrode ear 32, and the second connecting portion 22 is electrically connected to the electrode terminal 11.

[0080] It should be noted that the preparation process of the battery is as follows (the following selection of the positive electrode active material, negative electrode active material, conductive agent and binder is only for example and does not constitute a limitation on the scope of protection of this application):

[0081] (1) Preparation of positive electrode.

[0082] The prepared positive electrode active material (such as nickel-cobalt-manganese ternary, lithium iron phosphate, lithium manganese iron phosphate), conductive agent acetylene black, and binder PVDF are mixed in a mass ratio of 96:2:2, and solvent NMP is added. The mixture is stirred under the action of a vacuum mixer until the system becomes uniform to obtain a positive electrode slurry; the positive electrode slurry is evenly coated on both surfaces of the positive electrode current collector aluminum foil, dried at room temperature, and then transferred to an oven for further drying, and then cold pressed and cut to obtain a positive electrode sheet.

[0083] (2) Preparation of negative electrode sheet.

[0084] The negative electrode active material graphite or a mixture of graphite and other active materials (such as silicon-based materials) in different mass ratios, the conductive agent acetylene black, the thickener CMC, and the binder SBR are mixed in a mass ratio of 96.4:1:1.2:1.4, and deionized water is added as a solvent. The mixture is stirred under the action of a vacuum mixer until the system becomes uniform to obtain a negative electrode slurry; the negative electrode slurry is evenly coated on both surfaces of the negative electrode current collector copper foil, dried at room temperature, and then transferred to an oven for further drying, and then cold pressed and cut to obtain a negative electrode sheet.

[0085] (3) Preparation of electrolyte.

[0086] Ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) are mixed in a volume ratio of 1:1:1 to obtain an organic solvent. Then, fully dried lithium salt LiPF6 is dissolved in the mixed organic solvent to prepare an electrolyte with a concentration of 1 mol / L.

[0087] (4) Preparation of diaphragm.

[0088] A polyethylene film was selected as the separator.

[0089] (5) Preparation of lithium-ion batteries.

[0090] The positive electrode sheet, separator and negative electrode sheet are prepared in sequence through the lamination process, so that the separator is placed between the positive and negative electrode sheets to play an isolating role. After the battery cell is prepared, the battery cell is placed in the shell, the battery cover is welded, and the battery is subjected to processes such as liquid injection, formation, and constant capacity.

[0091] In the present application, the distance between the two side walls can be controlled by the shell wall thickness, etc.; the width of the connecting piece is adjusted by the connection piece selection; the tab thickness is controlled by the thickness of a single tab or the number of tab layers.

[0092] In the specific embodiment of the present application, lithium iron phosphate is selected as the positive electrode, and artificial graphite is selected as the negative electrode active material for example.

[0093] The battery cell temperature test method includes installing the battery cell 3 into the shell, sealing and welding the cover 4 and the shell 1, and providing the electrode terminal 11 on the cover 4. The battery is subjected to a temperature rise test. The specific test steps are as follows, wherein:

[0094] 1) For lithium iron phosphate batteries: charge at a constant current rate of 4C to 3.65V, and charge at a constant voltage until the current drops to 0.05C; connect a temperature sensor to the electrode terminal. During the charging process, sample the temperature of the electrode terminal to obtain the maximum temperature T of the electrode terminal area. When the maximum temperature T of the electrode terminal area is ≤45℃, it is good; when 45℃<T≤65℃, it is qualified; when T>65℃, it is unqualified.

[0095] As shown in the following table: Combining Examples 1-8 and Comparative Examples 1 and 2, it can be seen that when the formula range is met, the tabs are not inverted; and the battery temperature rise is qualified; in Comparative Example 1, the formula range is greater than the upper limit, the pole piece has serious material loss, and the battery capacity is significantly reduced compared with Example 6; and the tabs are inverted, causing the battery to short-circuit, and the electrode terminal temperature rise is greater than 65°C; in Comparative Example 2, the battery capacity is too low.

[0096]

[0097] 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 substitutions can be made without departing from the technical principles of the present invention. These improvements and substitutions should also be regarded as the scope of protection of the present invention.

Claims

1. A battery having a first direction, a second direction, and a third direction perpendicular to each other, characterized in that: include: a housing, wherein the housing is provided with electrode terminals; a connecting piece, which is disposed in the housing and electrically connected to the electrode terminal; A battery cell is disposed in the housing, the battery cell comprising a battery cell body and a negative electrode tab, the battery cell body comprising a negative electrode sheet, the negative electrode tab extending from one side of the battery cell body, the connecting sheet being opposite to and spaced from the side of the battery cell body where the negative electrode tab is provided, the negative electrode tab being welded to and electrically connected to the connecting sheet at one end away from the battery cell body, and the negative electrode sheet comprising a negative electrode active material layer and a current collector; Among them, the thickness of the battery cell body in the first direction is Dmm, and the minimum distance between the connecting piece and the negative electrode active material layer in the battery cell body in the direction perpendicular to the side of the battery cell body on which the negative electrode ear is provided is Hmm, 10mm≤D≤75mm, 1mm≤H≤8mm, 1.5≤D / H≤80, unit mm / mm.

2. The battery according to claim 1, characterized in that 5≤D / H≤70, unit: mm / mm.

3. The battery according to claim 1, characterized in that The battery cell is provided with a height of 1 mm or less and a height of 6 mm or less.

4. The battery according to claim 1, characterized in that There are at least two battery cells, 2mm≤H≤8mm.

5. The battery according to claim 1, characterized in that The connecting piece is opposite to and spaced from the side surface of the battery cell body in the second direction of the shell. The negative electrode ear extends from the side surface of the battery cell body in the second direction of the shell and is electrically connected to the connecting piece. The electrode terminal is provided on one side of the shell in the third direction. In the third direction of the shell, the distance between the end of the negative electrode ear close to the electrode terminal and the electrode terminal is h1mm, and the distance between the end of the connecting piece close to the electrode terminal and the electrode terminal is h2mm, wherein h2<h1.

6. The battery according to claim 5, characterized in that 1mm≤h1-h2≤8mm.

7. The battery according to claim 1, characterized in that The negative electrode ear extends from the side of the battery body in the second direction of the shell and is electrically connected to the connecting piece. The size of the negative electrode ear in the third direction of the shell is amm, and the size of the connecting piece in the third direction of the shell is cmm, wherein 0.15≤c / a≤0.

75.

8. The battery according to claim 1, characterized in that The thickness of the connecting piece is T1 mm, 0.2 mm ≤ T1 ≤ 3 mm, and / or the hardness of the connecting piece is 20-150 HB.

9. The battery according to claim 1, characterized in that The width of the connecting piece is W mm, 5 mm ≤ W ≤ 68 mm.

10. The battery according to claim 1, characterized in that There are at least two battery cells, and in the second direction, the connecting piece and the side of the battery body of each battery cell where the negative electrode ear is provided have an overlapping area, and the negative electrode ear of each battery cell is connected to the side of the connecting piece facing away from the battery cell, wherein 2mm≤H≤7.5mm.

11. The battery according to claim 1, characterized in that The battery cell body comprises a diaphragm and a negative electrode sheet stacked together, the negative electrode tab extending outward from one side of the negative electrode sheet, and the connecting sheet is opposite to and spaced from the side of the negative electrode sheet where the negative electrode tab is provided; The distance between the negative electrode sheet and the connecting sheet is L1 mm, and the distance between the separator and the connecting sheet is L2 mm, wherein L1>L2, 0.5 mm≤L1-L2≤5 mm.

12. The battery according to claim 1, characterized in that The thickness of the negative electrode active material layer on the negative electrode sheet is T2 mm, wherein T2 ≥ 0.06 mm, and 1.8 mm ≤ H ≤ 7 mm.

13. The battery according to claim 1, characterized in that The battery core is a laminated battery core, wherein 20≤D / H≤75, unit: mm / mm.

14. The battery according to claim 1, characterized in that The battery cell is a wound battery cell, wherein 12≤D / H≤70, unit: mm / mm.

15. The battery according to claim 1, characterized in that The negative electrode ear includes a connecting piece connecting portion and a battery cell body connecting portion respectively connected to the connecting piece and the battery cell body, and the negative electrode ear includes a plurality of sub-negative electrode ears. In a first direction, the battery cell body includes a first side and a second side facing away from each other. The plurality of sub-negative electrode ears are gathered in the direction from the first side to the second side and then bent around the connecting piece and connected to the side of the connecting piece facing away from the battery cell body. After the plurality of sub-negative electrode ears are gathered, an arc portion is formed between the battery cell body connecting portion and the first side. The connecting piece is at least partially arranged relative to the arc portion, and the size of the arc portion is Rmm, wherein 0.5mm≤R≤5mm.

16. The battery according to claim 15, characterized in that R≥0.5mm, 2.5mm≤H≤7.5mm.

17. The battery according to claim 1, characterized in that The length of the negative electrode tab extending from one side of the battery cell body is M mm, wherein 10 mm ≤ M ≤ 40 mm.

18. The battery according to claim 1, characterized in that The battery cell body includes a plurality of negative electrode sheets, each of which has a sub-negative electrode tab extending outward, and all the sub-negative electrode tabs form the negative electrode tab, wherein 1.8 mm ≤ H ≤ 7 mm.

19. The battery according to claim 1, characterized in that The battery cell body includes a plurality of negative electrode sheets, some of the negative electrode sheets have sub-negative electrode ears extending outward, and all the sub-negative electrode ears form the negative electrode ear, wherein 1.2 mm ≤ H ≤ 4 mm.

20. The battery according to claim 1, wherein The shell has an opening on at least one side in the third direction, the opening cover is provided with a cover body, the electrode terminal is provided on the cover body, the connecting piece includes a first connecting portion and a second connecting portion, and there is an angle between the first connecting portion and the second connecting portion, the first connecting portion is electrically connected to the negative electrode ear, and the second connecting portion is electrically connected to the electrode terminal.

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