Battery

Abstract

The invention discloses a battery which comprises a shell, a connecting piece and a battery cell, an electrode terminal is arranged on the shell, the connecting piece is arranged in the shell and electrically connected with the electrode terminal, the battery cell is arranged in the shell and comprises a battery cell body and a negative tab, the battery cell body comprises a negative plate, the negative tab extends out from one side of the battery cell body, and the negative plate is arranged on the connecting piece. The connecting piece and the side, provided with the negative tab, of the battery cell body are oppositely arranged in a spaced mode, the end, away from the battery cell body, of the negative tab is electrically connected with the connecting piece, the negative plate comprises a negative active material layer and a current collector, the thickness of the battery cell body is Dmm, the minimum distance between the connecting piece and the negative active material layer in the battery cell body is Hmm, and D / H is larger than or equal to 1.5 and smaller than or equal to 80. According to the invention, the energy density of the battery is ensured on the premise that the battery is not easy to fall off.

Description

Technical Field

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

[0002] Currently, a lithium-ion battery includes a housing, a cover plate, an electrode core and a connecting piece. The cover plate is covered on the housing, and a pole column is provided on the cover plate. The connecting piece and the electrode core are both located inside the housing, and the connecting piece is connected to the pole column together, and the tab extends out from the side of the electrode core.

[0003] During the battery manufacturing process, the connecting piece will be welded to the tab. The connecting piece is likely to squeeze the tab, and further squeeze the electrode plate of the electrode core. At the same time, since the negative electrode plate of the electrode core is closer to the connecting piece than the positive electrode plate, when squeezing the tab, it is easy to cause the negative electrode plate to be squeezed and the active material layer on the negative electrode plate to fall off. Summary of the Invention

[0004] The object of the present invention is to provide a battery to avoid the falling off of the active material layer on the negative electrode plate.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions: A battery having a first direction, a second direction and a third direction that are perpendicular to each other and intersect, includes: A housing provided with electrode terminals thereon; A connecting piece disposed inside the housing and electrically connected to the electrode terminals; An electrode core disposed inside the housing, the electrode core including an electrode core body and a negative tab. The electrode core body includes a negative electrode plate, and the negative tab extends out from one side of the electrode core body. The connecting piece is opposite to and spaced from the side of the electrode core body where the negative tab is provided. One end of the negative tab far from the electrode core body is electrically connected to the connecting piece. The negative electrode plate includes a negative active material layer and a current collector; Wherein, the thickness of the electrode core body in the first direction is D mm, and in the direction perpendicular to the side of the electrode core body where the negative tab is provided, the minimum distance between the connecting piece and the negative active material layer in the electrode core body is H mm, and 1.5 ≤ D / H ≤ 80.

[0006] Compared with the prior art, the battery according to an embodiment of the present invention has the following beneficial effects: 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 active material layers within the battery cell body, the thickness of the battery cell body and the distance between the connecting piece and the negative active material layer within the battery cell body are balanced, avoiding damage to the negative electrode sheet caused by the connecting piece, thereby causing the negative electrode sheet to drop material, and at the same time taking into account the energy density of the battery; it also avoids the risk of increased battery short circuit caused by the excessive pressure resulting in the reverse insertion of the tab. Description of the Drawings

[0007] Figure 1 is a three-dimensional view of the overall structure of an embodiment of the present invention; Figure 2 is an exploded view of the overall structure of an embodiment of the present invention; Figure 3 is a schematic diagram of the battery cell and the connecting piece of an embodiment of the present invention; Figure 4 is Figure 3 an enlarged view of part A in Figure 5 is a schematic diagram of the tab and the connecting piece of an embodiment of the present invention; Figure 6 is a schematic diagram of the dimensions between the tab and the connecting piece of an embodiment of the present invention; Figure 7 is a schematic diagram of the connecting piece and the battery cell of an embodiment of the present invention.

[0008] In the figure, 1. Housing; 11. Electrode terminal; 2. Connecting piece; 21. First connecting portion; 22. Second connecting portion; 3. Battery cell; 31. Battery cell body; 32. Negative tab; 321. Sub-negative tab; 322. Arc portion; 33. Negative active material layer; 4. Cover body. Detailed Embodiment

[0009] The following combines the drawings and embodiments to further describe in detail the specific embodiments of the present invention. The following embodiments are used to illustrate the present invention, but are not used to limit the scope of the present invention.

[0010] In the description of the present invention, it should be understood that the term "including" used in the specification of the present invention means the presence of the described features, integers, steps, operations, components and / or assemblies, but does not exclude the presence or addition of one or more other features, integers, steps, operations, components, assemblies and / or their groups. It should be understood that when we say that a component is "connected" to another component, it can be directly connected to other components, or there may also be intermediate components. The term "and / or" used here includes all or any unit and all combinations of one or more related listed items.

[0011] As shown Figures 1 to 7 in the figure, the present invention relates to a battery having a first direction, a second direction and a third direction that are perpendicular to each other. The battery includes a housing 1, a connecting piece 2 and an electric core 3. An electrode terminal 11 is provided on the housing 1. The connecting piece 2 is disposed inside the housing 1 and is electrically connected to the electrode terminal 11. The electric core 3 is disposed inside the housing 1. The electric core 3 includes an electric core body 31 and a negative electrode tab 32. The electric core body 31 includes a negative electrode sheet. The negative electrode tab 32 extends from one side of the electric core body 31. The connecting piece 2 is opposite to and spaced from the side of the electric core body 31 where the negative electrode tab 32 is provided. One end of the negative electrode tab 32 away from the electric core body 31 is electrically connected to the connecting piece 2. The negative electrode sheet includes a negative electrode active material layer 33 and a current collector. The first direction, the second direction and the third direction are the width direction, the length direction and the height direction of the housing, respectively.

[0012] Among them, the thickness of the electric core body 31 in the width direction of the housing 1 is D mm. In the direction perpendicular to the side of the electric core body 31 where the negative electrode tab 32 is provided, the minimum distance between the connecting piece 2 and the negative electrode active material layer 33 in the electric core body 31 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.

[0013] In the present invention, by comprehensively controlling the relationship between the thickness D of the electric core body 31 and the minimum distance H between the negative electrode active material layer 33 in the electric core body 31, the thickness of the electric core body 31 and the distance between the connecting piece 2 and the negative electrode active material layer 33 in the electric core body 31 are balanced, and 1.5 ≤ D / H ≤ 80 is maintained. It can avoid the force being transmitted to the negative electrode sheet through the negative electrode tab when the connecting piece 2 and the negative electrode tab are welded, thereby causing damage to the negative electrode sheet and further causing the negative electrode sheet to drop material, while taking into account the energy density of the battery; further, D / H cannot be too small, otherwise the thickness of the electric core body 31 will be too small and the distance between the connecting piece 2 and the negative electrode active material layer 33 in the electric core body 31 will be too large, resulting in less active material for the battery to actually exert its capacity and low energy density of the battery; D / H cannot be too large either, otherwise the thickness of the electric core body 31 will be too large, the demand for overcurrent energy will increase, the number of negative electrode tabs 32 led out from the electric core body 31 will increase, and the distance between the connecting piece 2 and the negative electrode active material layer 33 in the electric core body 31 will be too small. Then, after the connecting piece 2 and the negative electrode tab 32 are welded, the pressure is easily transmitted to the negative electrode sheet, increasing the risk of the negative electrode active material layer 33 on the negative electrode sheet dropping material.

[0014] It should be noted that the housing 1, specifically, the housing 1 is arranged on the outermost side of the battery cell 3 to protect the battery cell 3; the material of the housing 1 can be selected but is not limited to aluminum alloy, steel, etc.; specifically, it can be aluminum-manganese alloy, aluminum-magnesium alloy, stainless steel, nickel-plated steel, etc.

[0015] The connecting piece 2 is used to achieve current transmission and is electrically connected to the tab and the electrode terminal 11. The material of the connecting piece 2 can be aluminum, copper, etc.

[0016] The electrode terminal 11 serves as the current output terminal of the battery and is used to connect to an external busbar, etc., to achieve series and parallel connections between batteries; the electrode terminal 11 can include a positive electrode terminal and a negative electrode terminal; the material of the electrode terminal 11 can be aluminum, copper, copper-aluminum composite, etc. The tab serves as the current output terminal inside the battery cell 3 and is used to be electrically connected to the electrode terminal 11, etc. The tab can be cut from a current collector or can be a separately formed metal part. It can be understood that the positive tab 34 is electrically connected to the positive electrode plate in the battery cell 3, and the negative tab 32 is electrically connected to the negative electrode plate in the battery cell 3.

[0017] The battery cell 3 includes a positive electrode plate, a negative electrode plate, and a separator. The separator is arranged between the positive electrode plate and the negative electrode plate. The positive electrode plate, the negative electrode plate, and the separator are stacked to form the battery cell 3. The positive electrode plate includes a positive current collector and a positive active material layer, and the negative electrode plate includes a negative current collector and a negative active material layer 33. There is no particular limitation on the positive current collector as long as it has conductivity and does not cause adverse chemical changes in the battery. For example, stainless steel, aluminum, nickel, titanium, fired carbon, or aluminum or stainless steel surface-treated with one of carbon, nickel, titanium, silver, etc. can be used; the negative current collector can be made of copper, stainless steel, nickel, titanium, etc. In a specific embodiment, the positive electrode can use aluminum and the negative electrode can use copper. The positive active material layer includes a positive active material, and the positive active material includes nickel-cobalt-manganese ternary material, lithium iron phosphate material, lithium manganese iron phosphate material, etc.; the negative active material layer 33 includes a negative active material, and the negative active material includes artificial graphite, natural graphite, silicon-based material, etc.

[0018] In some embodiments, 5 ≤ D / H ≤ 70.

[0019] By further controlling 5 ≤ D / H ≤ 70, the risk of the negative active material layer 33 falling off caused by the connecting piece 2 is further reduced, while taking into account the battery energy density.

[0020] In some embodiments, 10 mm ≤ D ≤ 75 mm. The value of D can 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.

[0021] By controlling the thickness range of the battery cell body 31, the battery energy density can be improved, while reducing the subsequent contact with the connecting piece 2 and reducing the risk of the negative electrode sheet dropping material.

[0022] In some embodiments, 1mm ≤ H ≤ 8mm. The value of H can also be 2mm, 3mm, 4mm, 5mm, 6mm or 7mm.

[0023] 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 a too large H, resulting in low space utilization rate and low battery energy density in the housing 1; it can also avoid a too small H, resulting in a large pressure of the connecting piece 2 on the negative electrode sheet and increasing the risk of the negative electrode sheet dropping material.

[0024] In some embodiments, the battery cell 3 is provided with one, and 1mm ≤ H ≤ 6mm.

[0025] When only one battery cell 3 is provided in the housing 1 of the battery, then after the negative electrode tab 32 of the battery cell 3 is welded to the connecting piece 2, the risk of squeezing the negative electrode sheet of the battery cell 3 is small, so 1mm ≤ H ≤ 6mm can be maintained to ensure the battery energy density on the premise of preventing the battery from dropping material.

[0026] In some embodiments, the battery cell 3 is provided with at least two, and 2mm ≤ H ≤ 8mm.

[0027] When at least two battery cells 3 are provided in the housing 1 of the battery, then after the negative electrode tabs 32 of the battery cells 3 in the housing 1 are welded to the connecting piece 2, the risk of squeezing the negative electrode sheets of the battery cells 3 is large. Therefore, by maintaining 2mm ≤ H ≤ 8mm, the battery energy density is ensured on the premise of preventing the battery from dropping material.

[0028] In some embodiments, the connecting piece 2 and the battery cell body 31 are arranged opposite and spaced apart on the side surface in the length direction of the housing 1. The negative electrode tab 32 extends out from the side surface of the battery cell body 31 in the length direction of the housing 1 and is electrically connected to the connecting piece 2. One side of the housing 1 in the height direction is provided with the electrode terminal 11. In the height direction of the housing 1, the distance between the end of the negative electrode tab 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, where h2 < h1.

[0029] That is, the end of the connecting piece 2 close to the electrode terminal 11 protrudes from the end of the negative electrode tab 32 close to the electrode terminal 11. Thus, after the negative electrode tab 32 is welded to the connecting piece 2, the size of the subsequent electrical connection between the negative electrode tab 32 and the connecting piece 2 becomes smaller, avoiding affecting the overcurrent capacity of the negative electrode tab 32 again.

[0030] In some embodiments, 1 mm ≤ h1 - h2 ≤ 8 mm is maintained. The value of h1 - h2 can also be 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, or 7 mm.

[0031] Specifically, the difference between h1 and h2 cannot be too small, otherwise the negative tab 32 is closer to the edge of the battery cell body 31 in the third direction, and the negative electrode sheet at the edge is at the edge position itself, and the risk of material dropping is relatively high. If the connecting piece 2 applies force to the negative electrode sheet, then the risk of material dropping of the negative electrode 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 weldable area left by the connecting piece 2 for the negative tab 32 is small, and the overcurrent capacity of the battery will be affected. Therefore, 1 mm ≤ h1 - h2 ≤ 8 mm can be maintained to reduce the risk of material dropping while taking into account the overcurrent capacity.

[0032] In some embodiments, the negative tab 32 extends from the side surface of the battery cell body 31 in the length direction of the housing 1 and is electrically connected to the connecting piece 2. The dimension of the negative tab 32 in the height direction of the housing 1 is a mm, and the dimension of the connecting piece 2 in the height direction of the housing 1 is c mm, where a > c and 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.

[0033] That is to say, the dimension of the connecting piece 2 in the height direction of the housing 1 is smaller than the dimension of the negative tab 32 in the height direction of the housing 1. The relative area of the connecting piece 2 and the negative tab 32 is small, and the area region for applying pressure to the negative tab 32 is small, so as to further prevent the pressure of the connecting piece 2 from being transmitted to the negative tab 32 and then to the negative electrode active material layer 33 of the negative electrode sheet, resulting in material dropping of the negative electrode active material layer 33. At the same time, the relative area of the connecting piece 2 and the negative tab 32 cannot be too small, otherwise it will affect the welding area of the connecting piece 2 and the negative tab 32, affect the overcurrent capacity of the battery, and easily cause a large temperature rise of the battery.

[0034] 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.

[0035] By controlling 0.2 mm ≤ T1 ≤ 3 mm, it is possible to avoid the excessive thickness of the connecting piece 2, which exerts a large pressure on the negative electrode sheet and increases the risk of the negative electrode sheet falling off; it is also possible to avoid the large thickness of the connecting piece 2, which occupies the internal space of the housing 1 and results in a low battery energy density; at the same time, it is also possible to avoid the too small thickness of the connecting piece 2, which leads to poor overcurrent capacity and an increase in battery temperature rise. Similarly, by controlling the hardness of the connecting piece 2 to be 20 - 150 HB, it is possible to avoid a large impact on the negative electrode sheet when the connecting piece 2 collides with the negative electrode sheet in the battery cell body 31, which increases the risk of the negative electrode active material layer 33 on the negative electrode sheet falling off.

[0036] In some embodiments, the width of the connecting piece 2 is W mm, where 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.

[0037] By controlling the width of the connecting piece 2 within the range of 5 - 68 mm, the overcurrent and the influence on the negative electrode sheet are balanced. Avoiding the too small width of the connecting piece 2 results in a small welding area for the subsequent connection with the negative electrode tab 32, which affects the overcurrent capacity and increases the battery temperature rise; also avoiding the too large width of the connecting piece 2, the area opposite to the negative electrode tab 32 is large, and subsequently the area of the negative electrode sheet under pressure is large, and the risk of the negative electrode sheet falling off is high.

[0038] In some embodiments, there are at least two battery cells 3. In the length direction of the housing 1, the connecting piece 2 and the side of each battery cell 3 where the battery cell body 31 is provided with the negative electrode tab 32 have an overlapping area, and the negative electrode tab 32 of each battery cell 3 is connected to the side of the connecting piece 2 facing away from the battery cell 3, where 2 mm ≤ H ≤ 7.5 mm.

[0039] When there are at least two battery cells 3, the connecting piece 2 also covers all the battery cells 3 in the housing 1 in the length direction of the housing 1. At the same time, more negative electrode tabs 32 are led out from the battery cells 3, so that more negative electrode tabs 32 are welded on the connecting piece 2. By further controlling H within the range of 2 - 7.5 mm, the risk of the battery falling off is further reduced.

[0040] In some embodiments, the battery cell body 31 includes a separator and a negative electrode sheet stacked together. One side of the negative electrode sheet extends outward to form the negative electrode tab 32, and the connecting piece 2 is opposite to and spaced from the side of the negative electrode sheet where the negative electrode tab 32 is provided. The separator is used to insulate the positive electrode sheet and the negative electrode sheet to avoid short - circuit between the positive and negative electrodes. The material of the separator is PP or PE, etc.

[0041] Among them, 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. Here, L1 > L2, and 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.

[0042] That is to say, while maintaining 0.5 mm ≤ L1 - L2 ≤ 5 mm, compared with the negative electrode sheet, the separator is closer to the connecting sheet 2. The side of the separator close to the connecting sheet 2 extends beyond the side of the negative electrode sheet close to the connecting sheet 2. Thus, when the connecting sheet 2 approaches the negative electrode sheet, the separator can play a buffering role between the two, reducing the impact of the connecting sheet 2 on the negative electrode sheet and reducing the risk of battery material dropping. At the same time, L1 - L2 cannot be too small, otherwise the buffering ability of the separator is weak and it cannot fully avoid the impact of the connecting sheet 2 on the negative electrode sheet. L1 - L2 cannot be too large either, otherwise the separator is redundant and affects the heat dissipation of the battery cell 3.

[0043] Preferably, 1 mm ≤ L1 - L2 ≤ 3.5 mm to further improve the buffering effect and reduce the impact of the connecting sheet 2 on the negative electrode sheet.

[0044] In some embodiments, the thickness of the negative electrode active material layer 33 is T2 mm, where T2 ≥ 0.06 mm, and 1.8 mm ≤ H ≤ 7 mm.

[0045] Specifically, the 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 material dropping of the negative electrode active material layer 33 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 is further reduced to avoid material dropping of the negative electrode sheet.

[0046] Preferably, 0.06 mm ≤ T2 ≤ 2.5 mm. The value of T2 can also be 0.1 mm, 0.5 mm, 0.7 mm, 1 mm, 1.2 mm, 1.5 mm, 1.8 mm, 2 mm, 2.2 mm, or 2.4 mm. Further, 0.08 mm ≤ T2 ≤ 2 mm. Thereby, the impact of the connecting sheet 2 on the negative electrode sheet is further reduced to avoid material dropping of the negative electrode sheet.

[0047] In some embodiments, the battery cell 3 is a stacked battery cell, where 20 ≤ D / H ≤ 75.

[0048] The laminated battery cell includes a positive electrode sheet, a negative electrode sheet and a separator. The adjacent positive electrode sheets and the adjacent negative electrode sheets are not arranged continuously. The separator can be arranged continuously. For example, in a Z-shaped laminated battery cell, the separator can also be arranged discontinuously. The stacking between the positive electrode sheet, the negative electrode sheet and the separator of the laminated battery cell is relatively loose. After the negative electrode ear 32 is led out from the battery cell body 31, the stacking between the multi-layer sub-negative electrode ears 321 is also relatively loose. The negative active material layers 33 on the multiple negative electrode sheets are less subject to each other's internal pressure. By controlling D / H in the range of 20-75, the battery energy density can be improved, and the risk of battery material drop is small.

[0049] In some embodiments, the battery cell 3 is a wound battery cell, wherein 12≤D / H≤70.

[0050] 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 material falling of the battery. By controlling D / H within the range of 12-70, the risk of material falling of the negative electrode sheet after being subjected to the pressure of the connecting sheet 2 can be reduced, and the energy density of the battery can be avoided to be too low.

[0051] In some embodiments, the negative electrode ear includes a connecting piece connecting portion and a cell body connecting portion connected to the connecting piece and the cell body respectively, the negative electrode ear 32 includes a plurality of sub-negative electrode ears 321, in the width direction of the shell 1, the cell body 31 includes a first side and a second side facing away from each other, the plurality of sub-negative electrode ears 321 are gathered in the direction from the first side to the second side and then bent around the connecting piece 2, and connected to the side of the connecting piece 2 facing away from the cell body 31, and after the plurality of sub-negative electrode ears 321 are gathered, an arc portion 322 is formed between the cell body connecting portion and the first side, the connecting piece 2 is at least partially arranged opposite to the arc portion 322, and the size of the arc portion 322 is R mm, wherein 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.

[0052] That is, after the multiple sub-negative electrode ears 321 are gathered 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 sheet 2 affecting the negative electrode sheet. Therefore, by controlling R to be between 0.5-5mm, the arc portion 322 can be avoided from being too large to reduce the influence of the connecting sheet 2, thereby reducing the risk of material falling off on the negative electrode sheet; at the same time, it is also avoided that the arc portion 322 is too small. If the arc portion 322 is too small, the negative electrode ear 32 will be too close to the battery cell body 31, which will cause the negative electrode ear 32 to crush the negative electrode sheet of the battery cell body 31, and the negative electrode ear 32 will be easily broken.

[0053] Preferably, R ≥ 0.5 mm, and 2.5 mm ≤ H ≤ 7.5 mm.

[0054] 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.

[0055] In some embodiments, the length of the negative electrode ear 32 extending from one side of the battery body 31 is M mm, wherein 10 mm ≤ M ≤ 40 mm. The value of M may also be 15 mm, 20 mm, 25 mm, 30 mm, 35 mm or 38 mm.

[0056] Preferably, 15mm≤M≤35mm.

[0057] When H is too large, the risk of battery material falling off is low, but 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 current capacity.

[0058] It should be noted that when measuring the length M of the negative electrode ear 32 extending from one side of the battery body 31, the negative electrode ear 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 ear 32 and then measure the length of the measuring line.

[0059] In some embodiments, the battery cell body 31 includes a plurality of negative electrode sheets, each of the plurality of negative electrode sheets has a sub-negative electrode ear 321 extending outward, and all the sub-negative electrode ears 321 form the negative electrode ear 32, wherein 1.8 mm≤H≤7 mm.

[0060] The multiple negative electrode sheets of the battery cell body 31 are all extended outward with sub-negative electrode ears 321, and the multiple sub-negative electrode ears 321 are stacked together to form the negative electrode ear 32, so as to ensure the current capacity of the battery. 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.

[0061] In some embodiments, the battery cell body 31 includes a plurality of negative electrode sheets, and some of the negative electrode sheets extend outwardly with sub-negative electrode tabs 321, and all the sub-negative electrode tabs 321 form the negative electrode tab 32, wherein 1.2 mm ≤ H ≤ 4 mm.

[0062] Among the plurality of negative electrode sheets of the battery cell body 31, some negative electrode sheets extend outwardly with sub-negative electrode tabs 321, and the remaining negative electrode sheets are not provided with sub-negative electrode tabs 321. All the existing sub-negative electrode tabs 321 are stacked together to form the negative electrode tab 32. Therefore, the thickness of the negative electrode tab 32 will not be too large and is easy to bend. By further controlling H within the range of 1.2 - 4 mm, it is further avoided that the connecting piece 2 squeezes the negative electrode tab 32 and causes material dropping.

[0063] In some embodiments, at least one side of the housing 1 in the height direction has an opening, the opening is covered with a cover body 4, the electrode terminal 11 is disposed on the cover body 4, the connecting piece 2 is in an L shape, the connecting piece 2 includes a first connecting portion 21 and a second connecting portion 22, and there is an included angle between the first connecting portion 21 and the second connecting portion 22, and the included angle range is 80° - 110°. The first connecting portion 21 is electrically connected to the negative electrode tab 32, and the second connecting portion 22 is electrically connected to the electrode terminal 11.

[0064] It should be noted that the preparation process of the battery is as follows (the selection of the positive electrode active material, negative electrode active material, conductive agent and binder below is only an example and does not constitute a limitation on the protection scope of the present application): (1) Preparation of the positive electrode sheet.

[0065] Mix 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 in a mass ratio of 96:2:2, add the solvent NMP, and stir in a vacuum mixer until the system is homogeneous to obtain a positive electrode slurry; uniformly coat the positive electrode slurry on both surfaces of the positive electrode current collector aluminum foil, air-dry at room temperature and then transfer to an oven for further drying, and then obtain the positive electrode sheet through cold pressing and slitting.

[0066] (2) Preparation of the negative electrode sheet.

[0067] Mix the negative electrode active material graphite or a mixture of graphite and other active materials (such as silicon-based materials) obtained in different mass ratios, conductive agent acetylene black, thickening CMC, and binder SBR in a mass ratio of 96.4:1:1.2:1.4, add the solvent deionized water, and stir in a vacuum mixer until the system is homogeneous to obtain a negative electrode slurry; uniformly coat the negative electrode slurry on both surfaces of the negative electrode current collector copper foil, air-dry at room temperature and then transfer to an oven for further drying, and then obtain the negative electrode sheet through cold pressing and slitting.

[0068] (3) Preparation of electrolyte.

[0069] 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, the fully dried lithium salt LiPF6 is dissolved in the mixed organic solvent to prepare an electrolyte with a concentration of 1 mol / L.

[0070] (4) Preparation of separator.

[0071] A polyethylene film is selected as the separator.

[0072] (5) Preparation of lithium-ion battery.

[0073] The above-mentioned positive electrode sheet, separator, and negative electrode sheet are prepared in sequence through the stacking process, with the separator placed between the positive and negative electrode sheets to play an isolation role. After the battery cell is prepared, it is placed in a case, the battery cover is welded, and the battery is subjected to processes such as liquid injection, formation, and constant volume.

[0074] In this application, the distance between the two side walls can be adjusted by the wall thickness of the case, etc.; the width of the connecting piece is adjusted by selecting the connecting piece; the thickness of the tab is controlled by the thickness of a single tab or the number of tab layers.

[0075] In a specific embodiment of this application, lithium iron phosphate is selected as the positive electrode; artificial graphite is selected as the negative electrode active material for illustration.

[0076] Among them, the method for testing the temperature of the battery cell includes loading the battery cell 3 into the case, sealing and welding the cover 4 and the case 1. The cover 4 is provided with electrode terminals 11, and the temperature rise test of the battery is carried out. The specific test steps are as follows, where 1) For lithium iron phosphate batteries: Constant current charge at a rate of 4C to 3.65V and constant voltage charge until the current drops to 0.05C; connect a temperature sensor to the electrode terminal, and during the charging process, sample the temperature of the electrode terminal to obtain the highest temperature T in the electrode terminal area. When the highest temperature T in the electrode terminal area ≤ 45°C, it is good; when 45°C < T ≤ 65°C, it is qualified; when T > 65°C, it is unqualified.

[0077] The following table: Combining Examples 1-8 and Comparative Examples 1 and 2 shows that when the formula range is satisfied, the tabs do not show reverse insertion; and the temperature rise of the battery is qualified; in Comparative Example 1, the formula range is greater than the upper limit, serious material dropping occurs on the electrode sheet, and compared with Example 6, the battery capacity is significantly reduced; and the tabs show reverse insertion, causing the battery to short-circuit, and the temperature rise of the electrode terminal is greater than 65°C; in Comparative Example 2, the battery capacity is too low. The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the technical principle of the present invention, several improvements and substitutions can be made, and these improvements and substitutions should also be regarded as the protection scope of the present invention.

Claims

1. A battery having a first direction, a second direction, and a third direction that intersect perpendicularly to each other, characterized in that, Comprising: A housing, on which electrode terminals are provided; A connecting piece, which is arranged inside the housing and electrically connected to the electrode terminals; A battery cell, which is arranged inside the housing. The battery cell includes a battery cell body and a negative electrode tab. The battery cell body includes a negative electrode sheet. The negative electrode tab extends from one side of the battery cell body. The connecting piece is opposite to and spaced from the side of the battery cell body where the negative electrode tab is provided. One end of the negative electrode tab far from the battery cell body is electrically connected to the connecting piece. The negative electrode sheet includes a negative electrode active material layer and a current collector; Wherein, the thickness of the battery cell body in the first direction is D mm, and in the direction perpendicular to the side of the battery cell body where the negative electrode tab is provided, the minimum distance between the connecting piece and the negative electrode active material layer inside the battery cell body is H mm, and 1.5 ≤ D / H ≤ 80, with the unit of mm / mm.

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

3. The battery according to claim 1, characterized in that, 10 mm ≤ D ≤ 75 mm, and / or 1 mm ≤ H ≤ 8 mm.

4. The battery according to claim 1, characterized in that, There is one battery cell, and 1 mm ≤ H ≤ 6 mm.

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

6. The battery according to claim 1, wherein The connecting piece is opposite to and spaced from the side surface of the battery cell body in the second direction of the housing. The negative electrode tab extends from the side surface of the battery cell body in the second direction of the housing and is then electrically connected to the connecting piece. One side of the housing in the third direction is provided with the electrode terminals. In the third direction of the housing, the distance between one end of the negative electrode tab close to the electrode terminals and the electrode terminals is h1 mm, and the distance between one end of the connecting piece close to the electrode terminals and the electrode terminals is h2 mm, where h2 < h1.

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

8. The battery according to claim 1, characterized in that, The negative electrode tab extends from the side surface of the battery cell body in the second direction of the housing and is then electrically connected to the connecting piece. The size of the negative electrode tab in the third direction of the housing is a mm, and the size of the connecting piece in the third direction of the housing is c mm, where 0.15 ≤ c / a ≤ 0.

75.

9. The battery according to claim 1, wherein 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.

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

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

12. The battery according to claim 1, wherein The battery cell body includes a separator and a negative electrode sheet stacked together. One side of the negative electrode sheet extends outward with the negative electrode tab, and the connecting piece 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 piece is L1 mm, and the distance between the separator and the connecting piece is L2 mm, where L1 > L2 and 0.5 mm ≤ L1 - L2 ≤ 5 mm.

13. 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.

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

15. 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.

16. 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, 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, and 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 are connected to the side of the connecting piece facing away from the battery cell body, and 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 opposite to the arc portion, and the size of the arc portion is Rmm, wherein 0.5mm≤R≤5mm.

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

18. The battery according to claim 3, wherein The length of the negative electrode ear extending from one side of the battery body is Mmm, wherein 10mm≤M≤40mm.

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

20. The battery according to claim 1, wherein 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.

21. 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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