Battery

Abstract

The utility model relates to the technical field of batteries, and discloses a battery, which comprises a shell, a first pole piece group and a second pole piece group, the first pole piece group and the second pole piece group are stacked in the shell, a first step is formed at the junction of the first pole piece group and the second pole piece group along a first direction, and a second step is correspondingly formed on the shell. The second step comprises a first plane, a transition connecting surface and a second plane which are arranged in sequence, and the spacing distance L1 between the first end of the first pole piece group and the second end of the transition connecting surface in the first direction meets the condition that L1 is larger than or equal to 0.01 mm and smaller than or equal to 1.45 mm. The utility model can ensure that the shell and the pole piece groups do not interfere with each other, effectively improve the space utilization rate of the battery compartment, ensure that the lower-layer pole pieces at the junction of the upper and lower pole piece groups can be pressed, reduce the abnormal pressed space, ensure the pressed consistency of the whole pole pieces, improve the bonding performance of the junction, further prevent black spots at the junction in the later period, and improve the service life of the battery compartment. Therefore, the service life of the battery is prolonged.

Description

Technical Field

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

[0002] With the rapid development of electronic technology, various electronic devices are developing towards more intelligent, multi-functional, and multi-form directions, and their integration degree is getting higher and higher. To facilitate the arrangement of each component, the space of the battery compartment reserved in the electronic device is getting smaller and smaller. In order to improve the energy density of the battery in a limited space, special-shaped batteries are widely used.

[0003] Currently, a special-shaped battery includes at least two pole piece groups stacked up and down, and a stepped structure is designed at the junction of two or more different sizes of pole piece groups. However, abnormal pressure is likely to occur at the junction of the upper and lower two pole piece groups, resulting in black spots at the junction in the later stage and reducing the cycle life of the battery. Summary of the Utility Model

[0004] In view of this, the utility model provides a battery to solve the problem that abnormal pressure occurs at the junction of the battery pole piece groups in the related art, resulting in black spots at the interface in the later stage and reducing the battery cycle life.

[0005] The utility model provides a battery, including a first pole piece group, a second pole piece group and a housing. The first pole piece group and the second pole piece group are stacked in the housing, and along a first direction, a first end of the second pole piece group protrudes from a first end of the first pole piece group to form a first step;

[0006] The housing is provided with a second step corresponding to the first step, and the second step includes:

[0007] A first plane covering the first pole piece group;

[0008] A second plane covering the second pole piece group;

[0009] A transition connection surface, a first end of which is connected to the first plane and a second end of which is connected to the second plane. The interval distance between the first end of the first pole piece group and the second end of the transition connection surface along the first direction is L1, where 0.01 mm ≤ L1 ≤ 1.45 mm.

[0010] In an optional embodiment, the transition connection surface includes:

[0011] A first arc surface, a first end of which is connected to the first plane;

[0012] A second arc surface, a first end of which is directly connected to the second end of the first arc surface or connected through a transition surface, and a second end of which is connected to the second plane.

[0013] In an alternative embodiment, the radius of the first arc surface is R1, the radius of the second arc surface is R2, and the height of the second step is T1, where 0.5 ≤ R1 / T1 ≤ 7, and / or 0.5 ≤ R2 / T1 ≤ 7.

[0014] In an alternative embodiment, along the first direction, the distance between the first end and the second end of the transition connection surface is L2, where 0.3 mm ≤ L2 ≤ 4 mm.

[0015] In an alternative embodiment, L1 ≤ L2.

[0016] In an alternative embodiment, the first pole piece group includes at least one set of first pole pieces, second pole pieces and a first separator arranged in a stacked manner, the polarities of the first pole piece and the second pole piece are opposite, and the first separator is arranged between the first pole piece and the second pole piece; the second pole piece group includes at least one set of third pole pieces, fourth pole pieces and a second separator arranged in a stacked manner, the polarities of the third pole piece and the fourth pole piece are opposite, and the second separator is arranged between the third pole piece and the fourth pole piece;

[0017] The dimension of the first separator along the first direction is A1, and the distance between one end of the cavity of the housing adjacent to the first pole piece group and the second end of the transition connection surface along the first direction is W1, where A1 > W1; and / or,

[0018] The dimension of the second separator along the first direction is A2, and the dimension of the cavity of the housing along the first direction is W2, where A2 > W2.

[0019] In an alternative embodiment, it further includes:

[0020] A first tab corresponding to the first pole piece, a first insulating layer is coated on the first tab, the length of the first insulating layer along the extending direction of the first tab is H1, the height of the first step is T2, and the distance between the first end of the first pole piece and the first end of the fourth pole piece along the first direction is L8, where H1 ≥ L8 + T2.

[0021] In an alternative embodiment, the distance between one end of the housing adjacent to the first pole piece group and the second end of the transition connection surface along the first direction is W3, and the dimension of the housing along the first direction is W4, where A2 - A1 ≤ W4 - W3; and / or,

[0022] The dimension of the second pole piece along the first direction is B1, and the dimension of the fourth pole piece along the first direction is B2, where B2 - B1 ≤ W4 - W3; and / or,

[0023] The dimension of the first pole piece in the first direction is C1, and the dimension of the third pole piece in the first direction is C2, where C2 - C1 ≤ W4 - W3.

[0024] In an alternative embodiment, the connection between the first pole piece group and the second pole piece group is provided with a single-sided pole piece, and the single-sided pole piece includes a current collector and an active material layer provided on one side of the current collector.

[0025] At the connection between the first pole piece group and the second pole piece group, the current collectors of the two single-sided pole pieces are connected through an adhesive layer, and the distance between the first end of the adhesive layer and the first end of the transition connection surface in the first direction is L3, where L3 > 0.

[0026] In an alternative embodiment, the first pole piece of the first pole piece group and the third pole piece of the second pole piece group are connected through the adhesive layer.

[0027] In the first direction, the distance between the second end of the first first pole piece adjacent to the adhesive layer in the first pole piece group and the second end of the adhesive layer is W5, the distance between the second end of the first third pole piece adjacent to the adhesive layer in the second pole piece group and the second end of the adhesive layer is W6, and the distance between the first end of the first second pole piece adjacent to the adhesive layer in the first pole piece group and the first end of the adhesive layer is W7.

[0028] Wherein, W5 ≥ 0 mm, and / or,

[0029] W6 ≥ 0 mm, and / or,

[0030] W7 ≥ 0 mm.

[0031] In an alternative embodiment, 0.1 mm < L3 < 4 mm, and / or,

[0032] W5 ≥ 0.1 mm, and / or,

[0033] W6 ≥ 0.1 mm, and / or,

[0034] W7 ≥ 0.1 mm.

[0035] In an alternative embodiment, in the thickness direction of the battery, at least a part of the inner wall of the housing is in contact with the first pole piece group and / or the second pole piece group.

[0036] The battery provided by the present utility model has a stepped structure arranged in the battery, and the distance L1 between the first end of the first pole piece group and the second end of the transition connection surface in the first direction satisfies 0.01 mm ≤ L1 ≤ 1.45 mm. On the one hand, it can ensure that there is no interference between the housing and the pole piece group while effectively improving the space utilization rate of the battery compartment. On the other hand, it can ensure that the lower pole piece at the junction of the upper and lower pole piece groups can be pressed, reducing the abnormally pressured space, ensuring the consistent pressure on the entire pole piece, improving the bonding performance at the junction, thereby preventing black spots from appearing at the junction in the later stage, ensuring no abnormalities in the later battery cycles, and increasing the service life of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the specific embodiments of the present utility model or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present utility model. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0038] Figure 1 It is one of the partial cross-sectional views of the battery according to the embodiment of the present utility model;

[0039] Figure 2 is Figure 1 the second of the partial cross-sectional views of the battery shown;

[0040] Figure 3 It is one of the structural diagrams of the first pole piece group according to the embodiment of the present utility model;

[0041] Figure 4 It is one of the structural diagrams of the second pole piece group according to the embodiment of the present utility model;

[0042] Figure 5 It is the cross-sectional view of the battery according to the embodiment of the present utility model along the battery width direction;

[0043] Figure 6 It is the second of the structural diagrams of the first pole piece group according to the embodiment of the present utility model;

[0044] Figure 7 It is the second of the structural diagrams of the second pole piece group according to the embodiment of the present utility model;

[0045] Figure 8 It is the partial cross-sectional view of the first step according to the embodiment of the present utility model;

[0046] Figure 9 It is the partial cross-sectional view of the adhesive layer according to the embodiment of the present utility model;

[0047] Figure 10This is a cross-sectional view of the battery according to the embodiment of the present utility model along the battery length direction.

[0048] Description of reference numerals:

[0049] 1. First electrode assembly; 101. First end of the first electrode assembly; 102. First electrode; 1021. First end of the first electrode; 1022. Second end of the first electrode; 103. Second electrode; 1031. First end of the second electrode; 104. First separator; 2. Second electrode assembly; 201. First end of the second electrode assembly; 202. Third electrode; 2021. Second end of the third electrode; 203. Fourth electrode; 2031. First end of the fourth electrode; 204. Second separator; 3. Housing; 301. Flange; 4. First direction; 5. First step; 6. Second step; 601. First plane; 602. Second plane; 603. Transition connection surface; 6031. First end of the transition connection surface; 6032. Second end of the transition connection surface; 6033. First arc surface; 6034. Second arc surface; 7. First tab; 8. Adhesive layer; 801. First end of the adhesive layer; 802. Second end of the adhesive layer; 9. Thickness direction; 10. Second tab. Detailed implementation manners

[0050] To make the objectives, technical solutions and advantages of the embodiments of the present utility model clearer, the technical solutions in the embodiments of the present utility model will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present utility model. Apparently, the described embodiments are some but not all of the embodiments of the present utility model. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present utility model without creative efforts shall fall within the protection scope of the present utility model.

[0051] The following combines Figures 1 to 10 , and describes the embodiments of the present utility model.

[0052] According to the embodiments of the present utility model, a battery is provided, which can be applied to power-consuming terminals such as electronic devices such as mobile phones, power tools, and electric vehicles. Specifically, as Figure 1As shown in the figure, the battery includes a first electrode assembly 1, a second electrode assembly 2, and a housing 3. Generally, the first electrode assembly 1 and the second electrode assembly 2 are stacked in the housing 3. The first electrode assembly 1 and the second electrode assembly 2 are of a stacked structure. For example, the electrodes can be processed by die cutting or laser cutting with a mold, which is more likely to meet the production requirements of various-shaped batteries. Among them, the number of electrode assemblies in the housing 3 includes but is not limited to two, and can also be three, four, etc. The specific number can be determined according to actual design requirements. In each electrode assembly, the top electrode and the bottom electrode are usually single-sided electrodes. Specifically, an electrode includes a current collector and an active material layer located on the current collector. A double-sided electrode usually has active material layers formed on both surfaces of the current collector, while a single-sided electrode has an active material layer formed on only one surface of the current collector. For example, the connection between the upper and lower two electrode assemblies can be that the current collectors of two single-sided electrodes are bonded by double-sided tape. It should be noted that in terms of the placement position of the battery as shown in Figure 1 the figure, the up and down directions in the figure are the up and down orientations referred to. The upper end of the electrode assembly in the figure is the top referred to, and the lower end of the electrode assembly in the figure is the bottom referred to.

[0053] Furthermore, as shown in Figure 8 the figure, along the first direction 4, the first end 201 of the second electrode assembly protrudes from the first end 101 of the first electrode assembly to form a first step 5. In this way, at least two electrode assemblies with different sizes are stacked in the thickness direction 9 of the battery and form a stepped structure to construct a 3D special-shaped battery. This helps to improve the space utilization rate of the battery compartment. That is to say, in the same battery compartment space, the 3D special-shaped stacked battery can provide a higher capacity, and thus provide a higher endurance ability to better meet the usage needs of users.

[0054] Correspondingly, as shown in Figure 2 the figure, the housing 3 is provided with a second step 6 corresponding to the first step 5. Specifically, the second step 6 includes a first plane 601, a second plane 602, and a transition connection surface 603. As shown in Figure 1 the figure, the first plane 601 covers the first electrode assembly 1, and the second plane 602 covers the second electrode assembly 2. The first end 6031 of the transition connection surface is connected to the first plane 601, and the second end 6032 of the transition connection surface is connected to the second plane 602. And as shown in Figure 1As shown, the distance between the first end 101 of the first electrode sheet group and the second end 6032 of the transition connection surface along the first direction 4 is L1, where 0.01 mm ≤ L1 ≤ 1.45 mm. In this way, on the one hand, it can avoid interference between the electrode sheet group and the housing 3, preventing damage to the electrode sheet group or the housing 3. On the other hand, when the battery is under pressure, with L1 within the above numerical range, along the first direction 4, the second end 6032 of the transition connection surface can be closer to the first end 101 of the first electrode sheet group. Thus, at the junction of the upper and lower electrode sheet groups, it can ensure that both the position close to the first electrode sheet group 1 and the position far from the first electrode sheet group 1 of the second electrode sheet group 2 can be under pressure and the pressure consistency is better, reducing the abnormal pressure space, improving the adhesion at the junction, and further preventing black spots from appearing at the interface in the later stage, ensuring normal cycling in the later stage. If L1 is small, such as less than 0.01 mm, during the battery manufacturing process, the electrode sheet group is likely to interfere with the housing 3 and is not easily placed into the housing 3. If L1 is large, such as greater than 1.45 mm, it will cause waste of the internal space of the housing 3, reduce the occupied space of the electrode sheet group, lower the battery energy density, and increase the abnormal pressure space, thus leading to abnormal battery cycling.

[0055] With such a setting, by arranging a stepped structure in the battery and the distance L1 between the first end 101 of the first electrode sheet group and the second end 6032 of the transition connection surface along the first direction 4 satisfying 0.01 mm ≤ L1 ≤ 1.45 mm, on the one hand, it can ensure that there is no interference between the housing 3 and the electrode sheet group while effectively improving the space utilization rate of the battery compartment. On the other hand, it can ensure that the lower electrode sheet at the junction of the upper and lower electrode sheet groups can be under pressure, reduce the abnormal pressure space, ensure the pressure consistency of the entire electrode sheet, improve the adhesion performance at the junction, and further prevent black spots from appearing at the junction in the later stage, ensure normal battery cycling in the later stage, and improve the battery service life.

[0056] It should be noted that in the embodiments of the present invention, the first direction 4 can be the battery width direction, as shown in Figure 5 ; it can also be the battery length direction, as shown in Figure 10 . That is to say, the upper and lower two electrode sheet groups can have different sizes in the battery width direction, as shown in Figure 5 , to form a stepped structure; or, the upper and lower two electrode sheet groups can also have different sizes in the battery length direction, as shown in Figure 10 , to form a stepped structure; or, the upper and lower two electrode sheet groups can also have different sizes in both the battery width direction and the battery length direction simultaneously. Thus, the utilization rate of the battery compartment can be effectively improved, that is, the energy density of the battery can be increased within a limited space.

[0057] In some embodiments of the present invention, as shown in Figure 2As shown, the transition connection surface 603 includes a first arc surface 6033 and a second arc surface 6034. The radius of the first arc surface 6033 is R1, and its center is located inside the housing 3. The radius of the second arc surface 6034 is R2, and its center is located outside the housing 3. The first end, i.e., the right end, of the first arc surface 6033 is connected to the first plane 601, and the second end, i.e., the left end, of the second arc surface 6034 is connected to the second plane 602. The first end, i.e., the right end, of the second arc surface 6034 is directly connected to the second end, i.e., the left end, of the first arc surface 6033, or connected through a transition surface. Thus, a smooth transition of the stepped structure is achieved through the arc surface, which is convenient for processing and manufacturing. It should be noted that, taking the placement position of the battery as shown in Figure 1 and Figure 2 as an example, the left-right direction in the figure is the indicated left-right orientation.

[0058] Furthermore, as shown in Figure 1 and Figure 2 , the height of the second step 6 is T1. It should be noted that, taking the placement position of the battery as shown in Figure 1 and Figure 2 as an example, the thickness direction 9 of the battery in the figure is the indicated height direction of the second step 6, and the height of the second step 6 is the distance between the first plane 601 and the second plane 602. Among them, R1 and R2 need to be matched with T1, satisfying 0.5 ≤ R1 / T1 ≤ 7, and / or, 0.5 ≤ R2 / T1 ≤ 7. Specifically, R1 satisfies 0.1 mm ≤ R1 ≤ 5 mm, and / or, R2 satisfies 0.05 mm ≤ R2 ≤ 4 mm, and / or, T1 satisfies 0.15 mm ≤ T1 ≤ 3 mm.

[0059] By setting it in this way, by making R1 / T1 satisfy 0.5 ≤ R1 / T1 ≤ 7, and / or, R2 / T1 satisfy 0.5 ≤ R2 / T1 ≤ 7, it is possible to achieve the matching of the arc of the stepped transition surface with the step height, thereby facilitating the processing of the housing 3 and avoiding damage to the housing 3. Moreover, the change relationship of the arc curvature of the stepped transition surface will affect the size of the distance L1. Satisfying the above numerical range can also ensure that there is no abnormality in the pressure at the junction of the pole piece group, and then ensure that there is no abnormality in the later battery cycle. If R / T1 is small, such as less than 0.5, the radius of the transition surface arc is small, and the thickness of the metal layer of the housing 3 will also be correspondingly small, making it not easy to manufacture the housing 3 and the housing 3 is prone to damage. If R / T1 is large, such as greater than 7, the radius of the transition surface arc is large, and the housing 3 is prone to collapse, affecting the appearance quality of the battery.

[0060] In some embodiments of the present invention, as shown in Figure 1As shown, along the first direction 4, the distance between the first end 6031 and the second end 6032 of the transition connection surface is L2, where 0.3 mm ≤ L2 ≤ 4 mm. Preferably, 0.5 mm ≤ L2 ≤ 1.5 mm. With such a setting, by designing an appropriate distance L2, the second end 6032 of the transition connection surface can be closer to the first end 101 of the first electrode assembly. Thus, at the junction of the upper and lower electrode assemblies, it can be ensured that both the position near the first electrode assembly 1 and the position far from the first electrode assembly 1 of the second electrode assembly 2 can be pressed, and the consistency of the pressure on the entire electrode can be ensured, especially near the junction position of electrode assemblies of different sizes, thereby ensuring that the battery has a better cycle life. If L2 is smaller, such as less than 0.3 mm, the radius of the arc of the stepped transition surface is smaller, and the thickness of the metal layer of the housing 3 will also be correspondingly smaller, making it difficult to fabricate the housing 3 and the housing 3 is prone to breakage. If L2 is larger, such as greater than 4 mm, the radius of the arc of the stepped transition surface is larger, and the housing 3 is prone to collapse, affecting the appearance quality of the battery.

[0061] In some embodiments of the present invention, the distances L1 and L2 further satisfy L1 ≤ L2. With such a setting, on the one hand, it can improve the space occupancy rate of the electrode assembly and enhance the energy density of the battery. On the other hand, it can also ensure that there is no abnormal force near the junction position of electrode assemblies of different sizes, thereby increasing the service life of the battery. Otherwise, it will cause waste of the internal space of the housing 3, reduce the occupied space of the electrode assembly, lower the energy density of the battery, and increase the abnormal pressure space, thereby leading to abnormal battery cycling.

[0062] In some embodiments of the present invention, the first electrode assembly 1 includes at least one group of first electrodes 102, second electrodes 103, and first separators 104 stacked together, and the first separators 104 are disposed between the first electrodes 102 and the second electrodes 103. And the polarities of the first electrodes 102 and the second electrodes 103 are opposite, that is, one of them is a positive electrode and the other is a negative electrode. The second electrode assembly 2 includes at least one group of third electrodes 202, fourth electrodes 203, and second separators 204 stacked together, and the second separators 204 are disposed between the third electrodes 202 and the fourth electrodes 203. And the polarities of the third electrodes 202 and the fourth electrodes 203 are opposite, that is, one of them is a positive electrode and the other is a negative electrode. Specifically, the number of positive electrodes, negative electrodes, and separators in the electrode assembly needs to be determined according to actual design requirements.

[0063] In the embodiments of the present invention, the first direction 4 can be the width direction of the battery or the length direction of the battery. Taking the first direction 4 as the width direction of the battery as an example, as Figure 3 shown, the dimension of the first separator 104 along the first direction 4 is A1. As Figure 5As shown, the distance between the right end of the cavity of the housing 3 adjacent to the first electrode plate group 1, i.e., the second end 6032 of the transition connection surface along the first direction 4 is W1, where A1 > W1.

[0064] And / or, as Figure 4 shown, the dimension of the second separator 204 along the first direction 4 is A2. As Figure 5 shown, the dimension of the cavity of the housing 3 along the first direction 4 is W2, where A2 > W2. It should be noted that, taking the placement position of the battery shown as an example, the left - right direction in the figure is the indicated left - right orientation. The cavity of the housing 3 in the figure refers to the part of the housing 3 that encloses the electrode plate group and does not include the flanges 301 at both ends. By setting A1 and W1 to satisfy A1 > W1, and / or A2 and W2 to satisfy A2 > W2, the space occupancy rate of the electrode plate group can be greatly improved, thereby enhancing the energy density of the battery. Otherwise, it will cause waste of the internal space of the housing 3, reduce the occupied space of the electrode plate group, and lower the energy density of the battery. Figure 5 shown, the dimension of the cavity of the housing 3 along the first direction 4 is W2, where A2 > W2. It should be noted that, taking the placement position of the battery shown as an example, the left - right direction in the figure is the indicated left - right orientation. The cavity of the housing 3 in the figure refers to the part of the housing 3 that encloses the electrode plate group and does not include the flanges 301 at both ends. By setting A1 and W1 to satisfy A1 > W1, and / or A2 and W2 to satisfy A2 > W2, the space occupancy rate of the electrode plate group can be greatly improved, thereby enhancing the energy density of the battery. Otherwise, it will cause waste of the internal space of the housing 3, reduce the occupied space of the electrode plate group, and lower the energy density of the battery.

[0065] In addition, taking the first direction 4 as the battery length direction as an example, for the convenience of clear description respectively, as Figure 6 shown, the dimension of the first separator 104 along the first direction 4 is denoted as D1. As Figure 10 shown, the distance between the end of the cavity of the housing 3 adjacent to the first electrode plate group 1 and the second end 6032 of the transition connection surface along the first direction 4 is denoted as H3. Similarly, D1 ≥ > H3. And / or, as Figure 7 shown, the dimension of the second separator 204 along the first direction 4 is denoted as D2. As Figure 10 shown, the dimension of the cavity of the housing 3 along the first direction 4 is denoted as H4. Similarly, D2 ≥ > H4. Since the difference is only whether the first direction 4 is the battery width direction or the battery length direction, and they have the same technical effects, it will not be elaborated here.

[0066] In some embodiments of the present invention, the battery further includes a first tab 7. As Figure 6 shown, the first tab 7 is provided corresponding to the first electrode plate 102. Generally, the first tab 7 is connected to the first electrode plate 102 and the housing 3 respectively. A first insulating layer is coated on the first tab 7, and the length of the first insulating layer along the extending direction of the first tab 7 is H1. It should be noted that the insulating layer includes at least one of alumina, aluminum hydroxide, boehmite, polyethylene terephthalate, polyimide, polypropylene, polyvinylidene fluoride, and aramid.

[0067] As Figure 8 shown, the height of the first step 5 is T2. It should be noted that, taking Figure 8For the placement position of the battery shown, the thickness direction 9 of the battery in the figure is the height direction of the first step 5, and the height of the first step 5 is the distance between the top surface of the first electrode assembly 1 and the top surface of the second electrode assembly 2. The interval distance between the first end 1021 of the first electrode and the first end 2031 of the fourth electrode along the first direction 4 is L8, where H1 ≥ L8 + T2.

[0068] With such a setting, due to the existence of the mutually cooperating first step 5 and second step 6, the first tab 7 on the first electrode assembly 1 needs to be bent along the first step 5 in order to lead out the corresponding polarity. By arranging the first insulating layer on the first tab 7 and making H1, T2, and L8 satisfy H1 ≥ L8 + T2, the possibility of the first tab 7 short - circuiting with the lower electrode assembly 210 when folding along the first step 5 from the first electrode assembly 1 can be reduced, ensuring the safety of the battery.

[0069] In addition, the battery further includes a second tab 10, as Figure 7 shown, the second tab 10 corresponds to the third electrode 202. Similarly, a second insulating layer is coated on the second tab 10, and the length of the second insulating layer along the extending direction of the second tab 10 is H2, thereby preventing short - circuiting and causing safety problems. Specifically, both the first tab 7 and the second tab 10 can be set as positive tabs to lead out the corresponding polarity. In addition, the first electrode assembly 1 and the second electrode assembly 2 are respectively provided with negative tabs to lead out the corresponding polarity.

[0070] In the embodiment of the present utility model, the first direction 4 can be the width direction of the battery or the length direction of the battery. Taking the first direction 4 as the width direction of the battery as an example, as Figure 5 shown, the interval distance between the right end of the housing 3 adjacent to the first electrode assembly 1 (i.e., its right end) and the second end 6032 of the transition connection surface along the first direction 4 is W3, the dimension of the housing 3 along the first direction 4 is W4, where A2 - A1 ≤ W4 - W3.

[0071] And / or, as Figure 3 shown, the dimension of the second electrode 103 along the first direction 4 is B1. As Figure 4 shown, the dimension of the fourth electrode 203 along the first direction 4 is B2. Wherein, B2 - B1 ≤ W4 - W3.

[0072] And / or, as Figure 3 shown, the dimension of the first electrode 102 along the first direction 4 is C1. As Figure 4As shown, the dimension of the third pole piece 202 along the first direction 4 is C2. Among them, C2 - C1 ≤ W4 - W3. With such a setting, by satisfying A2 - A1 ≤ W4 - W3, and / or, B2 - B1 ≤ W4 - W3, and / or, C2 - C1 ≤ W4 - W3, the dimension of the pole piece group along the first direction 4 is less than or equal to the dimension of the housing 3 along the first direction 4, so that the interference between the pole piece group and the housing 3 can be reduced, and it is easier to realize the assembly of the pole piece group and the housing 3.

[0073] In addition, taking the first direction 4 as the battery length direction as an example, for the convenience of clear description respectively, as Figure 6 shown, the dimension of the first separator 104 along the first direction 4 is denoted as D1, the dimension of the second pole piece 103 along the first direction 4 is E1, and the dimension of the first pole piece 102 along the first direction 4 is F1. Correspondingly, as Figure 7 shown, the dimension of the second separator 204 along the first direction 4 is denoted as D2, the dimension of the fourth pole piece 203 along the first direction 4 is E2, and the dimension of the third pole piece 202 along the first direction 4 is F2. As Figure 10 shown, the distance between one end of the housing 3 adjacent to the first pole piece group 1 and the second end 6032 of the transition connection surface along the first direction 4 is H3, and the dimension of the housing 3 along the first direction 4 is H4. Similarly, D2 - D1 ≤ H4 - H3, and / or, E2 - E1 ≤ H4 - H3, and / or, F2 - F1 ≤ H4 - H3. Because the difference is only whether the first direction 4 is the battery width direction or the battery length direction, and they have the same technical effect, so it will not be elaborated here. It should be noted that, as Figure 10 shown, the housing 3 is not provided with a hem 301 along the battery length direction, so the dimension of the cavity of the housing along the first direction 4 is the same as the dimension of the housing 3 along the first direction 4. In addition, in the embodiment of the present invention, the first direction 4 can be the battery width direction or the battery length direction. That is to say, the relationship between the dimension of the pole piece group along the first direction 4 and the dimension of the housing 3 along the first direction 4 can satisfy the above dimension relationship in the battery width direction; or, it can also satisfy the above dimension relationship in the battery length direction; or, it can also satisfy the above dimension relationship both in the battery width direction and the battery length direction synchronously. Thus, the interference between the pole piece group and the housing 3 can be reduced, and it is easier to realize the assembly of the pole piece group and the housing 3.

[0074] In addition, in the embodiment of the present invention, as Figure 5 shown, on the side where the step structure is set, that is, the non-aligned end, along the battery width direction, the distance between the second pole piece group 2 and the cavity of the housing 3 is L4. On the side where the step structure is not set, that is, the aligned end, along the battery width direction, the distance between the pole piece group and the cavity of the housing 3 is L5. Similarly, as Figure 10As shown, on one side with the step structure, i.e., the non-aligned end, along the battery length direction, the distance between the second electrode assembly 2 and the cavity of the housing 3 is L6. On the side without the step structure, i.e., the aligned end, along the battery length direction, the distance between the electrode assembly and the cavity of the housing 3 is L7. Wherein, L4 ≥ 0 mm, and / or, L5 ≥ 0 mm, and / or, L6 ≥ 0 mm, and / or, L7 ≥ 0 mm. Preferably, L4 ≥ 0.1 mm, and / or, L5 ≥ 0.1 mm, and / or, L6 ≥ 0.1 mm, and / or, L7 ≥ 0.1 mm. Thereby, the interference between the electrode assembly and the housing 3 can be reduced, it is easier to realize the assembly of the electrode assembly and the housing 3, and at the same time, corner breakage can be prevented, and the safety during the battery cycle can be improved.

[0075] In some embodiments of the present invention, as Figure 9 shown, the connection between the first electrode assembly 1 and the second electrode assembly 2 is set as a single-sided electrode, that is to say, the connection between the upper and lower electrode assemblies is the connection of two single-sided electrodes. The single-sided electrode includes a current collector and an active material layer provided on one side of the current collector. At the connection between the first electrode assembly 1 and the second electrode assembly 2, the current collectors of the two single-sided electrodes are connected through an adhesive layer 8. The distance between the first end 801 of the adhesive layer and the first end 6031 of the transition connection surface along the first direction 4 is L3, wherein, L3 > 0. Specifically, for example, the adhesive layer 8 can be adhesive paper. Of course, in other embodiments, the first electrode assembly 1 and the second electrode assembly 2 can also be bonded through a separator. Thereby, different electrode assemblies can be bonded together in the thickness direction 9 to prevent different-sized electrode assemblies from separating from each other during production or dropping. With such a setting, by satisfying L3 > 0, the edge of the adhesive layer 8 protrudes beyond the edge of the first electrode assembly 1, preventing short circuit between the upper and lower electrodes, ensuring the battery safety, and at the same time, improving the space occupancy rate of the electrode assembly and enhancing the energy density of the battery. Further, the distance L3 also satisfies 0.1 mm < L3 < 4 mm, thereby improving the battery capacity on the premise of ensuring safety. If L3 is small, such as less than 0.1 mm, short circuit problems are likely to occur, reducing the battery safety. If L3 is large, such as greater than 4 mm, it will cause waste of the internal space of the housing 3, reduce the occupied space of the electrode assembly, and reduce the battery energy density.

[0076] In some embodiments of the present invention, as Figure 8As shown, the first pole piece 102 of the first pole piece group 1 and the third pole piece 202 of the second pole piece group 2 are connected by an adhesive layer 8. That is to say, the connection part between the upper and lower pole piece groups is the bonding of the first pole piece 102 and the third pole piece 202, and the first pole piece 102 and the third pole piece 202 are set as single-sided pole pieces. Along the first direction 4, the distance between the second end 1022 of the first first pole piece adjacent to the adhesive layer 8 in the first pole piece group 1 and the second end 802 of the adhesive layer is W5, the distance between the second end 2021 of the first third pole piece adjacent to the adhesive layer 8 in the second pole piece group 2 and the second end 802 of the adhesive layer is W6, and the distance between the first end 1031 of the first second pole piece adjacent to the adhesive layer 8 in the first pole piece group 1 and the first end 801 of the adhesive layer is W7. Among them, W5≥0 mm, and / or, W6≥0 mm, and / or, W7≥0 mm. With such a setting, by designing an appropriate distance of the adhesive layer 8, the battery safety performance can be effectively improved. Of course, in other embodiments, if the second pole piece 103 of the first pole piece group 1 and the fourth pole piece 203 of the second pole piece group 2 are connected by the adhesive layer 8, there is no limit to the size of the adhesive layer 8. Preferably, W5≥0.1 mm, and / or, W6≥0.1 mm, and / or, W7≥0.1 mm, so as to ensure battery safety.

[0077] In addition, in the embodiment of the present invention, as Figure 5 and Figure 10 shown, in the thickness direction 9 of the battery, at least part of the inner wall of the housing 3 is in contact with the first pole piece group 1 and / or the second pole piece group 2. With such a setting, in the thickness direction 9 of the battery, at least part of the inner walls at the upper and lower ends of the housing 3 is in contact with the adjacent pole pieces, so that the space occupancy rate of the pole piece group can be increased, and thus the energy density of the battery can be improved.

[0078] In the embodiment of the present invention, the test method for the cycling performance of the battery under normal temperature conditions is as follows:

[0079] 1. Take a 50% SOC battery and use a 600g±20g PPG thickness gauge to measure the initial thickness (T0) of the battery;

[0080] 2. Let the battery stand for 10 min at 25℃±3℃, discharge it to 3.0V at 0.2C, after standing for 10 min, charge it at a constant current of 0.5C to 4.50V, charge it at a constant voltage of 4.50V, with a cut-off current of 0.02C, stand for 10 min, then use a 600g±20g PPG thickness gauge to measure the battery thickness (Ta), (Ta / T0 - 1)*100% full charge thickness expansion rate; discharge it to 3.0V at 0.2C, after standing for 10 min, record the initial capacity C0 of the battery;

[0081] 3. Cycling: At 25°C ± 3°C, charge the battery at a constant current of 2.0C to 4.25V, then charge at a constant voltage of 4.25V with a cut-off current of 1.0C, then charge at a constant current of 1.0C to 4.50V, and then charge at a constant voltage of 4.50V with a cut-off current of 0.3C; discharge at a constant current of 0.7C to 3.0V; record the capacity C1 once for each cycle according to the aforementioned charge-discharge mechanism, and the capacity retention rate: C1 / C0 * 100%; continue cycling;

[0082] 4. After every 100 cycles, at 25°C ± 3°C, charge at a constant current of 0.5C to 4.50V, then charge at a constant voltage of 4.50V with a cut-off current of 0.02C, let it stand for 10 min, then use a 600g ± 20g PPG thickness gauge to measure the battery thickness (Tb), and calculate the thickness expansion rate: (Tb / T0 - 1) * 100%; discharge at 0.2C to 3.0V, let it stand for 10 min, and then record the recovery capacity Ca of the battery; the recovery capacity retention rate of the battery: Ca / C0 * 100%.

[0083] The test method for the cycling performance of the battery under high-temperature conditions is as follows:

[0084] 1. Take a battery with 50% SOC and use a 600g ± 20g PPG thickness gauge to measure the initial thickness (T0) of the battery;

[0085] 2. At 45°C ± 3°C, let the battery stand for 10 min, discharge at 0.2C to 3.0V, after standing for 10 min, charge at a constant current of 0.5C to 4.50V, then charge at a constant voltage of 4.50V with a cut-off current of 0.02C, let it stand for 10 min, then use a 600g ± 20g PPG thickness gauge to measure the battery thickness (Ta), and calculate the full-charge thickness expansion rate: (Ta / T0 - 1) * 100%; discharge at 0.2C to 3.0V, after standing for 10 min, record the initial capacity C0 of the battery;

[0086] 3. Cycling: At 45°C ± 3°C, charge the battery at a constant current of 2.0C to 4.25V, then charge at a constant voltage of 4.25V with a cut-off current of 1.0C, then charge at a constant current of 1.0C to 4.50V, and then charge at a constant voltage of 4.50V with a cut-off current of 0.5C; discharge at a constant current of 0.7C to 3.0V; record the capacity C1 once for each cycle according to the aforementioned charge-discharge mechanism, and the capacity retention rate: C1 / C0 * 100%; continue cycling;

[0087] 4. After every 100T in the middle, at 25°C ± 3°C, constant current charge at 0.5C to 4.50V, then constant voltage charge at 4.50V, with the cut-off current of 0.02C, let it stand for 10 minutes, then use a 600g ± 20g PPG thickness gauge to measure the battery thickness (Tb), and calculate the thickness expansion rate of (Tb / T0 - 1)*100%; discharge at 0.2C to 3.0V, after standing for 10 minutes, record the recovery capacity Ca of the battery; the recovery capacity retention rate of the battery is Ca / C0*100%.

[0088] The above test results are specifically shown in Table 1 and Table 2. It can be seen from the test results that for the battery of the present utility model, there is no abnormality in its later cycles, and the battery cycle life is effectively improved.

[0089] Table 1 Results of the number of cycles of the batteries in each embodiment

[0090]

[0091] Table 2 Results of the number of cycles of the batteries in each embodiment

[0092] Normal temperature cycle High temperature cycle Number of times 1600T 800T Capacity retention rate 80% or more 80% or more Recovery capacity retention rate 97% or more 97% or more Thickness expansion Within 12% Within 12%

[0093] Although the embodiments of the present utility model are described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present utility model, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A battery, characterized in that, It includes a first pole piece group (1), a second pole piece group (2) and a housing (3). The first pole piece group (1) and the second pole piece group (2) are stacked in the housing (3). Along a first direction (4), a first end (201) of the second pole piece group protrudes from a first end (101) of the first pole piece group to form a first step (5). The housing (3) is provided with a second step (6) corresponding to the first step (5). The second step (6) includes: A first plane (601) covering the first pole piece group (1); A second plane (602) covering the second pole piece group (2); A transition connection surface (603), a first end (6031) of which is connected to the first plane (601), and a second end (6032) of which is connected to the second plane (602). An interval distance between the first end (101) of the first pole piece group and the second end (6032) of the transition connection surface along the first direction (4) is L1, where 0.01 mm ≤ L1 ≤ 1.45 mm.

2. The battery according to claim 1, characterized in that, The transition connection surface (603) includes: A first arc surface (6033), a first end of which is connected to the first plane (601); A second arc surface (6034), a first end of which is directly connected to a second end of the first arc surface (6033) or connected through a transition surface, and a second end of which is connected to the second plane (602).

3. The battery according to claim 2, characterized in that, A radius of the first arc surface (6033) is R1, a radius of the second arc surface (6034) is R2, and a height of the second step (6) is T1, where 0.5 ≤ R1 / T1 ≤ 7, and / or 0.5 ≤ R2 / T1 ≤ 7.

4. The battery according to claim 1, characterized in that Along the first direction (4), an interval distance between the first end (6031) and the second end (6032) of the transition connection surface is L2, where 0.3 mm ≤ L2 ≤ 4 mm.

5. The battery according to claim 4, characterized in that, L1 ≤ L2.

6. The battery according to claim 1, characterized in that, The first pole piece group (1) includes at least one group of first pole pieces (102), second pole pieces (103) and a first separator (104) stacked. The first pole pieces (102) and the second pole pieces (103) have opposite polarities. The first separator (104) is disposed between the first pole pieces (102) and the second pole pieces (103). The second pole piece group (2) includes at least one group of third pole pieces (202), fourth pole pieces (203) and a second separator (204) stacked. The third pole pieces (202) and the fourth pole pieces (203) have opposite polarities. The second separator (204) is disposed between the third pole pieces (202) and the fourth pole pieces (203). A dimension of the first separator (104) along the first direction (4) is A1. An interval distance between an end of the cavity of the housing (3) adjacent to the first pole piece group (1) and the second end (6032) of the transition connection surface along the first direction (4) is W1, where A1 > W1; and / or The second diaphragm (204) has a dimension A2 in the first direction (4), and the cavity of the housing (3) has a dimension W2 in the first direction (4), where A2 > W2.

7. The battery according to claim 6, characterized in that, It further includes: A first tab (7) provided corresponding to the first electrode plate (102). A first insulating layer is coated on the first tab (7). The length of the first insulating layer in the extending direction of the first tab (7) is H1. The height of the first step (5) is T2. The distance between the first end (1021) of the first electrode plate and the first end (2031) of the fourth electrode plate in the first direction (4) is L8, where H1 ≥ L8 + T2.

8. The battery according to claim 6, characterized in that, The distance between the end of the housing (3) adjacent to the first electrode plate group (1) and the second end (6032) of the transition connection surface in the first direction (4) is W3, and the dimension of the housing (3) in the first direction (4) is W4, where A2 - A1 ≤ W4 - W3; and / or, The second electrode plate (103) has a dimension B1 in the first direction (4), and the fourth electrode plate (203) has a dimension B2 in the first direction (4), where B2 - B1 ≤ W4 - W3; and / or, The first electrode plate (102) has a dimension C1 in the first direction (4), and the third electrode plate (202) has a dimension C2 in the first direction (4), where C2 - C1 ≤ W4 - W3.

9. The battery according to claim 6, characterized in that, The connection between the first electrode plate group (1) and the second electrode plate group (2) is provided as a single-sided electrode plate. The single-sided electrode plate includes a current collector and an active material layer provided on one side of the current collector. At the connection between the first electrode plate group (1) and the second electrode plate group (2), the current collectors of the two single-sided electrode plates are connected through an adhesive layer (8). The distance between the first end (801) of the adhesive layer and the first end (6031) of the transition connection surface in the first direction (4) is L3, where L3 > 0.

10. The battery according to claim 9, characterized in that, The first electrode plate (102) of the first electrode plate group (1) and the third electrode plate (202) of the second electrode plate group (2) are connected through the adhesive layer (8). In the first direction (4), the distance between the second end (1022) of the first first electrode adjacent to the adhesive layer (8) in the first electrode plate group (1) and the second end (802) of the adhesive layer is W5. The distance between the second end (2021) of the first third electrode adjacent to the adhesive layer (8) in the second electrode plate group (2) and the second end (802) of the adhesive layer is W6. The distance between the first end (1031) of the first second electrode adjacent to the adhesive layer (8) in the first electrode plate group (1) and the first end (801) of the adhesive layer is W7. Wherein, W5 ≥ 0 mm, and / or, W6 ≥ 0 mm, and / or, W7 ≥ 0 mm.

11. The battery according to claim 10, wherein, 0.1 mm < L3 < 4 mm, and / or, W5 ≥ 0.1 mm, and / or, W6 ≥ 0.1 mm, and / or, W7 ≥ 0.1 mm.

12. The battery according to claim 1, characterized in that, In the thickness direction (9) of the battery, at least a part of the inner wall of the housing (3) is in contact with the first electrode assembly (1) and / or the second electrode assembly (2).

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